1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2010, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree
; use Atree
;
27 with Debug
; use Debug
;
28 with Einfo
; use Einfo
;
29 with Errout
; use Errout
;
30 with Exp_Ch2
; use Exp_Ch2
;
31 with Exp_Ch4
; use Exp_Ch4
;
32 with Exp_Ch11
; use Exp_Ch11
;
33 with Exp_Pakd
; use Exp_Pakd
;
34 with Exp_Util
; use Exp_Util
;
35 with Elists
; use Elists
;
36 with Eval_Fat
; use Eval_Fat
;
37 with Freeze
; use Freeze
;
39 with Nlists
; use Nlists
;
40 with Nmake
; use Nmake
;
42 with Output
; use Output
;
43 with Restrict
; use Restrict
;
44 with Rident
; use Rident
;
45 with Rtsfind
; use Rtsfind
;
47 with Sem_Aux
; use Sem_Aux
;
48 with Sem_Eval
; use Sem_Eval
;
49 with Sem_Ch3
; use Sem_Ch3
;
50 with Sem_Ch8
; use Sem_Ch8
;
51 with Sem_Res
; use Sem_Res
;
52 with Sem_Util
; use Sem_Util
;
53 with Sem_Warn
; use Sem_Warn
;
54 with Sinfo
; use Sinfo
;
55 with Sinput
; use Sinput
;
56 with Snames
; use Snames
;
57 with Sprint
; use Sprint
;
58 with Stand
; use Stand
;
59 with Targparm
; use Targparm
;
60 with Tbuild
; use Tbuild
;
61 with Ttypes
; use Ttypes
;
62 with Urealp
; use Urealp
;
63 with Validsw
; use Validsw
;
65 package body Checks
is
67 -- General note: many of these routines are concerned with generating
68 -- checking code to make sure that constraint error is raised at runtime.
69 -- Clearly this code is only needed if the expander is active, since
70 -- otherwise we will not be generating code or going into the runtime
73 -- We therefore disconnect most of these checks if the expander is
74 -- inactive. This has the additional benefit that we do not need to
75 -- worry about the tree being messed up by previous errors (since errors
76 -- turn off expansion anyway).
78 -- There are a few exceptions to the above rule. For instance routines
79 -- such as Apply_Scalar_Range_Check that do not insert any code can be
80 -- safely called even when the Expander is inactive (but Errors_Detected
81 -- is 0). The benefit of executing this code when expansion is off, is
82 -- the ability to emit constraint error warning for static expressions
83 -- even when we are not generating code.
85 -------------------------------------
86 -- Suppression of Redundant Checks --
87 -------------------------------------
89 -- This unit implements a limited circuit for removal of redundant
90 -- checks. The processing is based on a tracing of simple sequential
91 -- flow. For any sequence of statements, we save expressions that are
92 -- marked to be checked, and then if the same expression appears later
93 -- with the same check, then under certain circumstances, the second
94 -- check can be suppressed.
96 -- Basically, we can suppress the check if we know for certain that
97 -- the previous expression has been elaborated (together with its
98 -- check), and we know that the exception frame is the same, and that
99 -- nothing has happened to change the result of the exception.
101 -- Let us examine each of these three conditions in turn to describe
102 -- how we ensure that this condition is met.
104 -- First, we need to know for certain that the previous expression has
105 -- been executed. This is done principly by the mechanism of calling
106 -- Conditional_Statements_Begin at the start of any statement sequence
107 -- and Conditional_Statements_End at the end. The End call causes all
108 -- checks remembered since the Begin call to be discarded. This does
109 -- miss a few cases, notably the case of a nested BEGIN-END block with
110 -- no exception handlers. But the important thing is to be conservative.
111 -- The other protection is that all checks are discarded if a label
112 -- is encountered, since then the assumption of sequential execution
113 -- is violated, and we don't know enough about the flow.
115 -- Second, we need to know that the exception frame is the same. We
116 -- do this by killing all remembered checks when we enter a new frame.
117 -- Again, that's over-conservative, but generally the cases we can help
118 -- with are pretty local anyway (like the body of a loop for example).
120 -- Third, we must be sure to forget any checks which are no longer valid.
121 -- This is done by two mechanisms, first the Kill_Checks_Variable call is
122 -- used to note any changes to local variables. We only attempt to deal
123 -- with checks involving local variables, so we do not need to worry
124 -- about global variables. Second, a call to any non-global procedure
125 -- causes us to abandon all stored checks, since such a all may affect
126 -- the values of any local variables.
128 -- The following define the data structures used to deal with remembering
129 -- checks so that redundant checks can be eliminated as described above.
131 -- Right now, the only expressions that we deal with are of the form of
132 -- simple local objects (either declared locally, or IN parameters) or
133 -- such objects plus/minus a compile time known constant. We can do
134 -- more later on if it seems worthwhile, but this catches many simple
135 -- cases in practice.
137 -- The following record type reflects a single saved check. An entry
138 -- is made in the stack of saved checks if and only if the expression
139 -- has been elaborated with the indicated checks.
141 type Saved_Check
is record
143 -- Set True if entry is killed by Kill_Checks
146 -- The entity involved in the expression that is checked
149 -- A compile time value indicating the result of adding or
150 -- subtracting a compile time value. This value is to be
151 -- added to the value of the Entity. A value of zero is
152 -- used for the case of a simple entity reference.
154 Check_Type
: Character;
155 -- This is set to 'R' for a range check (in which case Target_Type
156 -- is set to the target type for the range check) or to 'O' for an
157 -- overflow check (in which case Target_Type is set to Empty).
159 Target_Type
: Entity_Id
;
160 -- Used only if Do_Range_Check is set. Records the target type for
161 -- the check. We need this, because a check is a duplicate only if
162 -- it has a the same target type (or more accurately one with a
163 -- range that is smaller or equal to the stored target type of a
167 -- The following table keeps track of saved checks. Rather than use an
168 -- extensible table. We just use a table of fixed size, and we discard
169 -- any saved checks that do not fit. That's very unlikely to happen and
170 -- this is only an optimization in any case.
172 Saved_Checks
: array (Int
range 1 .. 200) of Saved_Check
;
173 -- Array of saved checks
175 Num_Saved_Checks
: Nat
:= 0;
176 -- Number of saved checks
178 -- The following stack keeps track of statement ranges. It is treated
179 -- as a stack. When Conditional_Statements_Begin is called, an entry
180 -- is pushed onto this stack containing the value of Num_Saved_Checks
181 -- at the time of the call. Then when Conditional_Statements_End is
182 -- called, this value is popped off and used to reset Num_Saved_Checks.
184 -- Note: again, this is a fixed length stack with a size that should
185 -- always be fine. If the value of the stack pointer goes above the
186 -- limit, then we just forget all saved checks.
188 Saved_Checks_Stack
: array (Int
range 1 .. 100) of Nat
;
189 Saved_Checks_TOS
: Nat
:= 0;
191 -----------------------
192 -- Local Subprograms --
193 -----------------------
195 procedure Apply_Float_Conversion_Check
197 Target_Typ
: Entity_Id
);
198 -- The checks on a conversion from a floating-point type to an integer
199 -- type are delicate. They have to be performed before conversion, they
200 -- have to raise an exception when the operand is a NaN, and rounding must
201 -- be taken into account to determine the safe bounds of the operand.
203 procedure Apply_Selected_Length_Checks
205 Target_Typ
: Entity_Id
;
206 Source_Typ
: Entity_Id
;
207 Do_Static
: Boolean);
208 -- This is the subprogram that does all the work for Apply_Length_Check
209 -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
210 -- described for the above routines. The Do_Static flag indicates that
211 -- only a static check is to be done.
213 procedure Apply_Selected_Range_Checks
215 Target_Typ
: Entity_Id
;
216 Source_Typ
: Entity_Id
;
217 Do_Static
: Boolean);
218 -- This is the subprogram that does all the work for Apply_Range_Check.
219 -- Expr, Target_Typ and Source_Typ are as described for the above
220 -- routine. The Do_Static flag indicates that only a static check is
223 type Check_Type
is new Check_Id
range Access_Check
.. Division_Check
;
224 function Check_Needed
(Nod
: Node_Id
; Check
: Check_Type
) return Boolean;
225 -- This function is used to see if an access or division by zero check is
226 -- needed. The check is to be applied to a single variable appearing in the
227 -- source, and N is the node for the reference. If N is not of this form,
228 -- True is returned with no further processing. If N is of the right form,
229 -- then further processing determines if the given Check is needed.
231 -- The particular circuit is to see if we have the case of a check that is
232 -- not needed because it appears in the right operand of a short circuited
233 -- conditional where the left operand guards the check. For example:
235 -- if Var = 0 or else Q / Var > 12 then
239 -- In this example, the division check is not required. At the same time
240 -- we can issue warnings for suspicious use of non-short-circuited forms,
243 -- if Var = 0 or Q / Var > 12 then
249 Check_Type
: Character;
250 Target_Type
: Entity_Id
;
251 Entry_OK
: out Boolean;
255 -- This routine is used by Enable_Range_Check and Enable_Overflow_Check
256 -- to see if a check is of the form for optimization, and if so, to see
257 -- if it has already been performed. Expr is the expression to check,
258 -- and Check_Type is 'R' for a range check, 'O' for an overflow check.
259 -- Target_Type is the target type for a range check, and Empty for an
260 -- overflow check. If the entry is not of the form for optimization,
261 -- then Entry_OK is set to False, and the remaining out parameters
262 -- are undefined. If the entry is OK, then Ent/Ofs are set to the
263 -- entity and offset from the expression. Check_Num is the number of
264 -- a matching saved entry in Saved_Checks, or zero if no such entry
267 function Get_Discriminal
(E
: Entity_Id
; Bound
: Node_Id
) return Node_Id
;
268 -- If a discriminal is used in constraining a prival, Return reference
269 -- to the discriminal of the protected body (which renames the parameter
270 -- of the enclosing protected operation). This clumsy transformation is
271 -- needed because privals are created too late and their actual subtypes
272 -- are not available when analysing the bodies of the protected operations.
273 -- This function is called whenever the bound is an entity and the scope
274 -- indicates a protected operation. If the bound is an in-parameter of
275 -- a protected operation that is not a prival, the function returns the
277 -- To be cleaned up???
279 function Guard_Access
282 Ck_Node
: Node_Id
) return Node_Id
;
283 -- In the access type case, guard the test with a test to ensure
284 -- that the access value is non-null, since the checks do not
285 -- not apply to null access values.
287 procedure Install_Static_Check
(R_Cno
: Node_Id
; Loc
: Source_Ptr
);
288 -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
289 -- Constraint_Error node.
291 function Range_Or_Validity_Checks_Suppressed
292 (Expr
: Node_Id
) return Boolean;
293 -- Returns True if either range or validity checks or both are suppressed
294 -- for the type of the given expression, or, if the expression is the name
295 -- of an entity, if these checks are suppressed for the entity.
297 function Selected_Length_Checks
299 Target_Typ
: Entity_Id
;
300 Source_Typ
: Entity_Id
;
301 Warn_Node
: Node_Id
) return Check_Result
;
302 -- Like Apply_Selected_Length_Checks, except it doesn't modify
303 -- anything, just returns a list of nodes as described in the spec of
304 -- this package for the Range_Check function.
306 function Selected_Range_Checks
308 Target_Typ
: Entity_Id
;
309 Source_Typ
: Entity_Id
;
310 Warn_Node
: Node_Id
) return Check_Result
;
311 -- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
312 -- just returns a list of nodes as described in the spec of this package
313 -- for the Range_Check function.
315 ------------------------------
316 -- Access_Checks_Suppressed --
317 ------------------------------
319 function Access_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
321 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
322 return Is_Check_Suppressed
(E
, Access_Check
);
324 return Scope_Suppress
(Access_Check
);
326 end Access_Checks_Suppressed
;
328 -------------------------------------
329 -- Accessibility_Checks_Suppressed --
330 -------------------------------------
332 function Accessibility_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
334 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
335 return Is_Check_Suppressed
(E
, Accessibility_Check
);
337 return Scope_Suppress
(Accessibility_Check
);
339 end Accessibility_Checks_Suppressed
;
341 -----------------------------
342 -- Activate_Division_Check --
343 -----------------------------
345 procedure Activate_Division_Check
(N
: Node_Id
) is
347 Set_Do_Division_Check
(N
, True);
348 Possible_Local_Raise
(N
, Standard_Constraint_Error
);
349 end Activate_Division_Check
;
351 -----------------------------
352 -- Activate_Overflow_Check --
353 -----------------------------
355 procedure Activate_Overflow_Check
(N
: Node_Id
) is
357 Set_Do_Overflow_Check
(N
, True);
358 Possible_Local_Raise
(N
, Standard_Constraint_Error
);
359 end Activate_Overflow_Check
;
361 --------------------------
362 -- Activate_Range_Check --
363 --------------------------
365 procedure Activate_Range_Check
(N
: Node_Id
) is
367 Set_Do_Range_Check
(N
, True);
368 Possible_Local_Raise
(N
, Standard_Constraint_Error
);
369 end Activate_Range_Check
;
371 ---------------------------------
372 -- Alignment_Checks_Suppressed --
373 ---------------------------------
375 function Alignment_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
377 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
378 return Is_Check_Suppressed
(E
, Alignment_Check
);
380 return Scope_Suppress
(Alignment_Check
);
382 end Alignment_Checks_Suppressed
;
384 -------------------------
385 -- Append_Range_Checks --
386 -------------------------
388 procedure Append_Range_Checks
389 (Checks
: Check_Result
;
391 Suppress_Typ
: Entity_Id
;
392 Static_Sloc
: Source_Ptr
;
395 Internal_Flag_Node
: constant Node_Id
:= Flag_Node
;
396 Internal_Static_Sloc
: constant Source_Ptr
:= Static_Sloc
;
398 Checks_On
: constant Boolean :=
399 (not Index_Checks_Suppressed
(Suppress_Typ
))
401 (not Range_Checks_Suppressed
(Suppress_Typ
));
404 -- For now we just return if Checks_On is false, however this should
405 -- be enhanced to check for an always True value in the condition
406 -- and to generate a compilation warning???
408 if not Checks_On
then
413 exit when No
(Checks
(J
));
415 if Nkind
(Checks
(J
)) = N_Raise_Constraint_Error
416 and then Present
(Condition
(Checks
(J
)))
418 if not Has_Dynamic_Range_Check
(Internal_Flag_Node
) then
419 Append_To
(Stmts
, Checks
(J
));
420 Set_Has_Dynamic_Range_Check
(Internal_Flag_Node
);
426 Make_Raise_Constraint_Error
(Internal_Static_Sloc
,
427 Reason
=> CE_Range_Check_Failed
));
430 end Append_Range_Checks
;
432 ------------------------
433 -- Apply_Access_Check --
434 ------------------------
436 procedure Apply_Access_Check
(N
: Node_Id
) is
437 P
: constant Node_Id
:= Prefix
(N
);
440 -- We do not need checks if we are not generating code (i.e. the
441 -- expander is not active). This is not just an optimization, there
442 -- are cases (e.g. with pragma Debug) where generating the checks
443 -- can cause real trouble).
445 if not Expander_Active
then
449 -- No check if short circuiting makes check unnecessary
451 if not Check_Needed
(P
, Access_Check
) then
455 -- No check if accessing the Offset_To_Top component of a dispatch
456 -- table. They are safe by construction.
458 if Tagged_Type_Expansion
459 and then Present
(Etype
(P
))
460 and then RTU_Loaded
(Ada_Tags
)
461 and then RTE_Available
(RE_Offset_To_Top_Ptr
)
462 and then Etype
(P
) = RTE
(RE_Offset_To_Top_Ptr
)
467 -- Otherwise go ahead and install the check
469 Install_Null_Excluding_Check
(P
);
470 end Apply_Access_Check
;
472 -------------------------------
473 -- Apply_Accessibility_Check --
474 -------------------------------
476 procedure Apply_Accessibility_Check
479 Insert_Node
: Node_Id
)
481 Loc
: constant Source_Ptr
:= Sloc
(N
);
482 Param_Ent
: constant Entity_Id
:= Param_Entity
(N
);
483 Param_Level
: Node_Id
;
484 Type_Level
: Node_Id
;
487 if Inside_A_Generic
then
490 -- Only apply the run-time check if the access parameter has an
491 -- associated extra access level parameter and when the level of the
492 -- type is less deep than the level of the access parameter, and
493 -- accessibility checks are not suppressed.
495 elsif Present
(Param_Ent
)
496 and then Present
(Extra_Accessibility
(Param_Ent
))
497 and then UI_Gt
(Object_Access_Level
(N
), Type_Access_Level
(Typ
))
498 and then not Accessibility_Checks_Suppressed
(Param_Ent
)
499 and then not Accessibility_Checks_Suppressed
(Typ
)
502 New_Occurrence_Of
(Extra_Accessibility
(Param_Ent
), Loc
);
505 Make_Integer_Literal
(Loc
, Type_Access_Level
(Typ
));
507 -- Raise Program_Error if the accessibility level of the access
508 -- parameter is deeper than the level of the target access type.
510 Insert_Action
(Insert_Node
,
511 Make_Raise_Program_Error
(Loc
,
514 Left_Opnd
=> Param_Level
,
515 Right_Opnd
=> Type_Level
),
516 Reason
=> PE_Accessibility_Check_Failed
));
518 Analyze_And_Resolve
(N
);
520 end Apply_Accessibility_Check
;
522 --------------------------------
523 -- Apply_Address_Clause_Check --
524 --------------------------------
526 procedure Apply_Address_Clause_Check
(E
: Entity_Id
; N
: Node_Id
) is
527 AC
: constant Node_Id
:= Address_Clause
(E
);
528 Loc
: constant Source_Ptr
:= Sloc
(AC
);
529 Typ
: constant Entity_Id
:= Etype
(E
);
530 Aexp
: constant Node_Id
:= Expression
(AC
);
533 -- Address expression (not necessarily the same as Aexp, for example
534 -- when Aexp is a reference to a constant, in which case Expr gets
535 -- reset to reference the value expression of the constant.
537 procedure Compile_Time_Bad_Alignment
;
538 -- Post error warnings when alignment is known to be incompatible. Note
539 -- that we do not go as far as inserting a raise of Program_Error since
540 -- this is an erroneous case, and it may happen that we are lucky and an
541 -- underaligned address turns out to be OK after all.
543 --------------------------------
544 -- Compile_Time_Bad_Alignment --
545 --------------------------------
547 procedure Compile_Time_Bad_Alignment
is
549 if Address_Clause_Overlay_Warnings
then
551 ("?specified address for& may be inconsistent with alignment ",
554 ("\?program execution may be erroneous (RM 13.3(27))",
556 Set_Address_Warning_Posted
(AC
);
558 end Compile_Time_Bad_Alignment
;
560 -- Start of processing for Apply_Address_Clause_Check
563 -- See if alignment check needed. Note that we never need a check if the
564 -- maximum alignment is one, since the check will always succeed.
566 -- Note: we do not check for checks suppressed here, since that check
567 -- was done in Sem_Ch13 when the address clause was processed. We are
568 -- only called if checks were not suppressed. The reason for this is
569 -- that we have to delay the call to Apply_Alignment_Check till freeze
570 -- time (so that all types etc are elaborated), but we have to check
571 -- the status of check suppressing at the point of the address clause.
574 or else not Check_Address_Alignment
(AC
)
575 or else Maximum_Alignment
= 1
580 -- Obtain expression from address clause
582 Expr
:= Expression
(AC
);
584 -- The following loop digs for the real expression to use in the check
587 -- For constant, get constant expression
589 if Is_Entity_Name
(Expr
)
590 and then Ekind
(Entity
(Expr
)) = E_Constant
592 Expr
:= Constant_Value
(Entity
(Expr
));
594 -- For unchecked conversion, get result to convert
596 elsif Nkind
(Expr
) = N_Unchecked_Type_Conversion
then
597 Expr
:= Expression
(Expr
);
599 -- For (common case) of To_Address call, get argument
601 elsif Nkind
(Expr
) = N_Function_Call
602 and then Is_Entity_Name
(Name
(Expr
))
603 and then Is_RTE
(Entity
(Name
(Expr
)), RE_To_Address
)
605 Expr
:= First
(Parameter_Associations
(Expr
));
607 if Nkind
(Expr
) = N_Parameter_Association
then
608 Expr
:= Explicit_Actual_Parameter
(Expr
);
611 -- We finally have the real expression
618 -- See if we know that Expr has a bad alignment at compile time
620 if Compile_Time_Known_Value
(Expr
)
621 and then (Known_Alignment
(E
) or else Known_Alignment
(Typ
))
624 AL
: Uint
:= Alignment
(Typ
);
627 -- The object alignment might be more restrictive than the
630 if Known_Alignment
(E
) then
634 if Expr_Value
(Expr
) mod AL
/= 0 then
635 Compile_Time_Bad_Alignment
;
641 -- If the expression has the form X'Address, then we can find out if
642 -- the object X has an alignment that is compatible with the object E.
643 -- If it hasn't or we don't know, we defer issuing the warning until
644 -- the end of the compilation to take into account back end annotations.
646 elsif Nkind
(Expr
) = N_Attribute_Reference
647 and then Attribute_Name
(Expr
) = Name_Address
648 and then Has_Compatible_Alignment
(E
, Prefix
(Expr
)) = Known_Compatible
653 -- Here we do not know if the value is acceptable. Stricly we don't have
654 -- to do anything, since if the alignment is bad, we have an erroneous
655 -- program. However we are allowed to check for erroneous conditions and
656 -- we decide to do this by default if the check is not suppressed.
658 -- However, don't do the check if elaboration code is unwanted
660 if Restriction_Active
(No_Elaboration_Code
) then
663 -- Generate a check to raise PE if alignment may be inappropriate
666 -- If the original expression is a non-static constant, use the
667 -- name of the constant itself rather than duplicating its
668 -- defining expression, which was extracted above.
670 -- Note: Expr is empty if the address-clause is applied to in-mode
671 -- actuals (allowed by 13.1(22)).
673 if not Present
(Expr
)
675 (Is_Entity_Name
(Expression
(AC
))
676 and then Ekind
(Entity
(Expression
(AC
))) = E_Constant
677 and then Nkind
(Parent
(Entity
(Expression
(AC
))))
678 = N_Object_Declaration
)
680 Expr
:= New_Copy_Tree
(Expression
(AC
));
682 Remove_Side_Effects
(Expr
);
685 Insert_After_And_Analyze
(N
,
686 Make_Raise_Program_Error
(Loc
,
693 (RTE
(RE_Integer_Address
), Expr
),
695 Make_Attribute_Reference
(Loc
,
696 Prefix
=> New_Occurrence_Of
(E
, Loc
),
697 Attribute_Name
=> Name_Alignment
)),
698 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
699 Reason
=> PE_Misaligned_Address_Value
),
700 Suppress
=> All_Checks
);
705 -- If we have some missing run time component in configurable run time
706 -- mode then just skip the check (it is not required in any case).
708 when RE_Not_Available
=>
710 end Apply_Address_Clause_Check
;
712 -------------------------------------
713 -- Apply_Arithmetic_Overflow_Check --
714 -------------------------------------
716 -- This routine is called only if the type is an integer type, and a
717 -- software arithmetic overflow check may be needed for op (add, subtract,
718 -- or multiply). This check is performed only if Software_Overflow_Checking
719 -- is enabled and Do_Overflow_Check is set. In this case we expand the
720 -- operation into a more complex sequence of tests that ensures that
721 -- overflow is properly caught.
723 procedure Apply_Arithmetic_Overflow_Check
(N
: Node_Id
) is
724 Loc
: constant Source_Ptr
:= Sloc
(N
);
725 Typ
: Entity_Id
:= Etype
(N
);
726 Rtyp
: Entity_Id
:= Root_Type
(Typ
);
729 -- An interesting special case. If the arithmetic operation appears as
730 -- the operand of a type conversion:
734 -- and all the following conditions apply:
736 -- arithmetic operation is for a signed integer type
737 -- target type type1 is a static integer subtype
738 -- range of x and y are both included in the range of type1
739 -- range of x op y is included in the range of type1
740 -- size of type1 is at least twice the result size of op
742 -- then we don't do an overflow check in any case, instead we transform
743 -- the operation so that we end up with:
745 -- type1 (type1 (x) op type1 (y))
747 -- This avoids intermediate overflow before the conversion. It is
748 -- explicitly permitted by RM 3.5.4(24):
750 -- For the execution of a predefined operation of a signed integer
751 -- type, the implementation need not raise Constraint_Error if the
752 -- result is outside the base range of the type, so long as the
753 -- correct result is produced.
755 -- It's hard to imagine that any programmer counts on the exception
756 -- being raised in this case, and in any case it's wrong coding to
757 -- have this expectation, given the RM permission. Furthermore, other
758 -- Ada compilers do allow such out of range results.
760 -- Note that we do this transformation even if overflow checking is
761 -- off, since this is precisely about giving the "right" result and
762 -- avoiding the need for an overflow check.
764 -- Note: this circuit is partially redundant with respect to the similar
765 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
766 -- with cases that do not come through here. We still need the following
767 -- processing even with the Exp_Ch4 code in place, since we want to be
768 -- sure not to generate the arithmetic overflow check in these cases
769 -- (Exp_Ch4 would have a hard time removing them once generated).
771 if Is_Signed_Integer_Type
(Typ
)
772 and then Nkind
(Parent
(N
)) = N_Type_Conversion
775 Target_Type
: constant Entity_Id
:=
776 Base_Type
(Entity
(Subtype_Mark
(Parent
(N
))));
790 if Is_Integer_Type
(Target_Type
)
791 and then RM_Size
(Root_Type
(Target_Type
)) >= 2 * RM_Size
(Rtyp
)
793 Tlo
:= Expr_Value
(Type_Low_Bound
(Target_Type
));
794 Thi
:= Expr_Value
(Type_High_Bound
(Target_Type
));
797 (Left_Opnd
(N
), LOK
, Llo
, Lhi
, Assume_Valid
=> True);
799 (Right_Opnd
(N
), ROK
, Rlo
, Rhi
, Assume_Valid
=> True);
802 and then Tlo
<= Llo
and then Lhi
<= Thi
803 and then Tlo
<= Rlo
and then Rhi
<= Thi
805 Determine_Range
(N
, VOK
, Vlo
, Vhi
, Assume_Valid
=> True);
807 if VOK
and then Tlo
<= Vlo
and then Vhi
<= Thi
then
808 Rewrite
(Left_Opnd
(N
),
809 Make_Type_Conversion
(Loc
,
810 Subtype_Mark
=> New_Occurrence_Of
(Target_Type
, Loc
),
811 Expression
=> Relocate_Node
(Left_Opnd
(N
))));
813 Rewrite
(Right_Opnd
(N
),
814 Make_Type_Conversion
(Loc
,
815 Subtype_Mark
=> New_Occurrence_Of
(Target_Type
, Loc
),
816 Expression
=> Relocate_Node
(Right_Opnd
(N
))));
818 Set_Etype
(N
, Target_Type
);
820 Rtyp
:= Root_Type
(Typ
);
821 Analyze_And_Resolve
(Left_Opnd
(N
), Target_Type
);
822 Analyze_And_Resolve
(Right_Opnd
(N
), Target_Type
);
824 -- Given that the target type is twice the size of the
825 -- source type, overflow is now impossible, so we can
826 -- safely kill the overflow check and return.
828 Set_Do_Overflow_Check
(N
, False);
836 -- Now see if an overflow check is required
839 Siz
: constant Int
:= UI_To_Int
(Esize
(Rtyp
));
840 Dsiz
: constant Int
:= Siz
* 2;
847 -- Skip check if back end does overflow checks, or the overflow flag
848 -- is not set anyway, or we are not doing code expansion, or the
849 -- parent node is a type conversion whose operand is an arithmetic
850 -- operation on signed integers on which the expander can promote
851 -- later the operands to type Integer (see Expand_N_Type_Conversion).
853 -- Special case CLI target, where arithmetic overflow checks can be
854 -- performed for integer and long_integer
856 if Backend_Overflow_Checks_On_Target
857 or else not Do_Overflow_Check
(N
)
858 or else not Expander_Active
859 or else (Present
(Parent
(N
))
860 and then Nkind
(Parent
(N
)) = N_Type_Conversion
861 and then Integer_Promotion_Possible
(Parent
(N
)))
863 (VM_Target
= CLI_Target
and then Siz
>= Standard_Integer_Size
)
868 -- Otherwise, generate the full general code for front end overflow
869 -- detection, which works by doing arithmetic in a larger type:
875 -- Typ (Checktyp (x) op Checktyp (y));
877 -- where Typ is the type of the original expression, and Checktyp is
878 -- an integer type of sufficient length to hold the largest possible
881 -- If the size of check type exceeds the size of Long_Long_Integer,
882 -- we use a different approach, expanding to:
884 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
886 -- where xxx is Add, Multiply or Subtract as appropriate
888 -- Find check type if one exists
890 if Dsiz
<= Standard_Integer_Size
then
891 Ctyp
:= Standard_Integer
;
893 elsif Dsiz
<= Standard_Long_Long_Integer_Size
then
894 Ctyp
:= Standard_Long_Long_Integer
;
896 -- No check type exists, use runtime call
899 if Nkind
(N
) = N_Op_Add
then
900 Cent
:= RE_Add_With_Ovflo_Check
;
902 elsif Nkind
(N
) = N_Op_Multiply
then
903 Cent
:= RE_Multiply_With_Ovflo_Check
;
906 pragma Assert
(Nkind
(N
) = N_Op_Subtract
);
907 Cent
:= RE_Subtract_With_Ovflo_Check
;
912 Make_Function_Call
(Loc
,
913 Name
=> New_Reference_To
(RTE
(Cent
), Loc
),
914 Parameter_Associations
=> New_List
(
915 OK_Convert_To
(RTE
(RE_Integer_64
), Left_Opnd
(N
)),
916 OK_Convert_To
(RTE
(RE_Integer_64
), Right_Opnd
(N
))))));
918 Analyze_And_Resolve
(N
, Typ
);
922 -- If we fall through, we have the case where we do the arithmetic
923 -- in the next higher type and get the check by conversion. In these
924 -- cases Ctyp is set to the type to be used as the check type.
926 Opnod
:= Relocate_Node
(N
);
928 Opnd
:= OK_Convert_To
(Ctyp
, Left_Opnd
(Opnod
));
931 Set_Etype
(Opnd
, Ctyp
);
932 Set_Analyzed
(Opnd
, True);
933 Set_Left_Opnd
(Opnod
, Opnd
);
935 Opnd
:= OK_Convert_To
(Ctyp
, Right_Opnd
(Opnod
));
938 Set_Etype
(Opnd
, Ctyp
);
939 Set_Analyzed
(Opnd
, True);
940 Set_Right_Opnd
(Opnod
, Opnd
);
942 -- The type of the operation changes to the base type of the check
943 -- type, and we reset the overflow check indication, since clearly no
944 -- overflow is possible now that we are using a double length type.
945 -- We also set the Analyzed flag to avoid a recursive attempt to
948 Set_Etype
(Opnod
, Base_Type
(Ctyp
));
949 Set_Do_Overflow_Check
(Opnod
, False);
950 Set_Analyzed
(Opnod
, True);
952 -- Now build the outer conversion
954 Opnd
:= OK_Convert_To
(Typ
, Opnod
);
956 Set_Etype
(Opnd
, Typ
);
958 -- In the discrete type case, we directly generate the range check
959 -- for the outer operand. This range check will implement the
960 -- required overflow check.
962 if Is_Discrete_Type
(Typ
) then
965 (Expression
(N
), Typ
, CE_Overflow_Check_Failed
);
967 -- For other types, we enable overflow checking on the conversion,
968 -- after setting the node as analyzed to prevent recursive attempts
969 -- to expand the conversion node.
972 Set_Analyzed
(Opnd
, True);
973 Enable_Overflow_Check
(Opnd
);
978 when RE_Not_Available
=>
981 end Apply_Arithmetic_Overflow_Check
;
983 ----------------------------
984 -- Apply_Constraint_Check --
985 ----------------------------
987 procedure Apply_Constraint_Check
990 No_Sliding
: Boolean := False)
992 Desig_Typ
: Entity_Id
;
995 if Inside_A_Generic
then
998 elsif Is_Scalar_Type
(Typ
) then
999 Apply_Scalar_Range_Check
(N
, Typ
);
1001 elsif Is_Array_Type
(Typ
) then
1003 -- A useful optimization: an aggregate with only an others clause
1004 -- always has the right bounds.
1006 if Nkind
(N
) = N_Aggregate
1007 and then No
(Expressions
(N
))
1009 (First
(Choices
(First
(Component_Associations
(N
)))))
1015 if Is_Constrained
(Typ
) then
1016 Apply_Length_Check
(N
, Typ
);
1019 Apply_Range_Check
(N
, Typ
);
1022 Apply_Range_Check
(N
, Typ
);
1025 elsif (Is_Record_Type
(Typ
)
1026 or else Is_Private_Type
(Typ
))
1027 and then Has_Discriminants
(Base_Type
(Typ
))
1028 and then Is_Constrained
(Typ
)
1030 Apply_Discriminant_Check
(N
, Typ
);
1032 elsif Is_Access_Type
(Typ
) then
1034 Desig_Typ
:= Designated_Type
(Typ
);
1036 -- No checks necessary if expression statically null
1038 if Known_Null
(N
) then
1039 if Can_Never_Be_Null
(Typ
) then
1040 Install_Null_Excluding_Check
(N
);
1043 -- No sliding possible on access to arrays
1045 elsif Is_Array_Type
(Desig_Typ
) then
1046 if Is_Constrained
(Desig_Typ
) then
1047 Apply_Length_Check
(N
, Typ
);
1050 Apply_Range_Check
(N
, Typ
);
1052 elsif Has_Discriminants
(Base_Type
(Desig_Typ
))
1053 and then Is_Constrained
(Desig_Typ
)
1055 Apply_Discriminant_Check
(N
, Typ
);
1058 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1059 -- this check if the constraint node is illegal, as shown by having
1060 -- an error posted. This additional guard prevents cascaded errors
1061 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1063 if Can_Never_Be_Null
(Typ
)
1064 and then not Can_Never_Be_Null
(Etype
(N
))
1065 and then not Error_Posted
(N
)
1067 Install_Null_Excluding_Check
(N
);
1070 end Apply_Constraint_Check
;
1072 ------------------------------
1073 -- Apply_Discriminant_Check --
1074 ------------------------------
1076 procedure Apply_Discriminant_Check
1079 Lhs
: Node_Id
:= Empty
)
1081 Loc
: constant Source_Ptr
:= Sloc
(N
);
1082 Do_Access
: constant Boolean := Is_Access_Type
(Typ
);
1083 S_Typ
: Entity_Id
:= Etype
(N
);
1087 function Denotes_Explicit_Dereference
(Obj
: Node_Id
) return Boolean;
1088 -- A heap object with an indefinite subtype is constrained by its
1089 -- initial value, and assigning to it requires a constraint_check.
1090 -- The target may be an explicit dereference, or a renaming of one.
1092 function Is_Aliased_Unconstrained_Component
return Boolean;
1093 -- It is possible for an aliased component to have a nominal
1094 -- unconstrained subtype (through instantiation). If this is a
1095 -- discriminated component assigned in the expansion of an aggregate
1096 -- in an initialization, the check must be suppressed. This unusual
1097 -- situation requires a predicate of its own.
1099 ----------------------------------
1100 -- Denotes_Explicit_Dereference --
1101 ----------------------------------
1103 function Denotes_Explicit_Dereference
(Obj
: Node_Id
) return Boolean is
1106 Nkind
(Obj
) = N_Explicit_Dereference
1108 (Is_Entity_Name
(Obj
)
1109 and then Present
(Renamed_Object
(Entity
(Obj
)))
1110 and then Nkind
(Renamed_Object
(Entity
(Obj
))) =
1111 N_Explicit_Dereference
);
1112 end Denotes_Explicit_Dereference
;
1114 ----------------------------------------
1115 -- Is_Aliased_Unconstrained_Component --
1116 ----------------------------------------
1118 function Is_Aliased_Unconstrained_Component
return Boolean is
1123 if Nkind
(Lhs
) /= N_Selected_Component
then
1126 Comp
:= Entity
(Selector_Name
(Lhs
));
1127 Pref
:= Prefix
(Lhs
);
1130 if Ekind
(Comp
) /= E_Component
1131 or else not Is_Aliased
(Comp
)
1136 return not Comes_From_Source
(Pref
)
1137 and then In_Instance
1138 and then not Is_Constrained
(Etype
(Comp
));
1139 end Is_Aliased_Unconstrained_Component
;
1141 -- Start of processing for Apply_Discriminant_Check
1145 T_Typ
:= Designated_Type
(Typ
);
1150 -- Nothing to do if discriminant checks are suppressed or else no code
1151 -- is to be generated
1153 if not Expander_Active
1154 or else Discriminant_Checks_Suppressed
(T_Typ
)
1159 -- No discriminant checks necessary for an access when expression is
1160 -- statically Null. This is not only an optimization, it is fundamental
1161 -- because otherwise discriminant checks may be generated in init procs
1162 -- for types containing an access to a not-yet-frozen record, causing a
1163 -- deadly forward reference.
1165 -- Also, if the expression is of an access type whose designated type is
1166 -- incomplete, then the access value must be null and we suppress the
1169 if Known_Null
(N
) then
1172 elsif Is_Access_Type
(S_Typ
) then
1173 S_Typ
:= Designated_Type
(S_Typ
);
1175 if Ekind
(S_Typ
) = E_Incomplete_Type
then
1180 -- If an assignment target is present, then we need to generate the
1181 -- actual subtype if the target is a parameter or aliased object with
1182 -- an unconstrained nominal subtype.
1184 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1185 -- subtype to the parameter and dereference cases, since other aliased
1186 -- objects are unconstrained (unless the nominal subtype is explicitly
1190 and then (Present
(Param_Entity
(Lhs
))
1191 or else (Ada_Version
< Ada_05
1192 and then not Is_Constrained
(T_Typ
)
1193 and then Is_Aliased_View
(Lhs
)
1194 and then not Is_Aliased_Unconstrained_Component
)
1195 or else (Ada_Version
>= Ada_05
1196 and then not Is_Constrained
(T_Typ
)
1197 and then Denotes_Explicit_Dereference
(Lhs
)
1198 and then Nkind
(Original_Node
(Lhs
)) /=
1201 T_Typ
:= Get_Actual_Subtype
(Lhs
);
1204 -- Nothing to do if the type is unconstrained (this is the case where
1205 -- the actual subtype in the RM sense of N is unconstrained and no check
1208 if not Is_Constrained
(T_Typ
) then
1211 -- Ada 2005: nothing to do if the type is one for which there is a
1212 -- partial view that is constrained.
1214 elsif Ada_Version
>= Ada_05
1215 and then Has_Constrained_Partial_View
(Base_Type
(T_Typ
))
1220 -- Nothing to do if the type is an Unchecked_Union
1222 if Is_Unchecked_Union
(Base_Type
(T_Typ
)) then
1226 -- Suppress checks if the subtypes are the same. the check must be
1227 -- preserved in an assignment to a formal, because the constraint is
1228 -- given by the actual.
1230 if Nkind
(Original_Node
(N
)) /= N_Allocator
1232 or else not Is_Entity_Name
(Lhs
)
1233 or else No
(Param_Entity
(Lhs
)))
1236 or else (Do_Access
and then Designated_Type
(Typ
) = S_Typ
))
1237 and then not Is_Aliased_View
(Lhs
)
1242 -- We can also eliminate checks on allocators with a subtype mark that
1243 -- coincides with the context type. The context type may be a subtype
1244 -- without a constraint (common case, a generic actual).
1246 elsif Nkind
(Original_Node
(N
)) = N_Allocator
1247 and then Is_Entity_Name
(Expression
(Original_Node
(N
)))
1250 Alloc_Typ
: constant Entity_Id
:=
1251 Entity
(Expression
(Original_Node
(N
)));
1254 if Alloc_Typ
= T_Typ
1255 or else (Nkind
(Parent
(T_Typ
)) = N_Subtype_Declaration
1256 and then Is_Entity_Name
(
1257 Subtype_Indication
(Parent
(T_Typ
)))
1258 and then Alloc_Typ
= Base_Type
(T_Typ
))
1266 -- See if we have a case where the types are both constrained, and all
1267 -- the constraints are constants. In this case, we can do the check
1268 -- successfully at compile time.
1270 -- We skip this check for the case where the node is a rewritten`
1271 -- allocator, because it already carries the context subtype, and
1272 -- extracting the discriminants from the aggregate is messy.
1274 if Is_Constrained
(S_Typ
)
1275 and then Nkind
(Original_Node
(N
)) /= N_Allocator
1285 -- S_Typ may not have discriminants in the case where it is a
1286 -- private type completed by a default discriminated type. In that
1287 -- case, we need to get the constraints from the underlying_type.
1288 -- If the underlying type is unconstrained (i.e. has no default
1289 -- discriminants) no check is needed.
1291 if Has_Discriminants
(S_Typ
) then
1292 Discr
:= First_Discriminant
(S_Typ
);
1293 DconS
:= First_Elmt
(Discriminant_Constraint
(S_Typ
));
1296 Discr
:= First_Discriminant
(Underlying_Type
(S_Typ
));
1299 (Discriminant_Constraint
(Underlying_Type
(S_Typ
)));
1305 -- A further optimization: if T_Typ is derived from S_Typ
1306 -- without imposing a constraint, no check is needed.
1308 if Nkind
(Original_Node
(Parent
(T_Typ
))) =
1309 N_Full_Type_Declaration
1312 Type_Def
: constant Node_Id
:=
1314 (Original_Node
(Parent
(T_Typ
)));
1316 if Nkind
(Type_Def
) = N_Derived_Type_Definition
1317 and then Is_Entity_Name
(Subtype_Indication
(Type_Def
))
1318 and then Entity
(Subtype_Indication
(Type_Def
)) = S_Typ
1326 DconT
:= First_Elmt
(Discriminant_Constraint
(T_Typ
));
1328 while Present
(Discr
) loop
1329 ItemS
:= Node
(DconS
);
1330 ItemT
:= Node
(DconT
);
1332 -- For a discriminated component type constrained by the
1333 -- current instance of an enclosing type, there is no
1334 -- applicable discriminant check.
1336 if Nkind
(ItemT
) = N_Attribute_Reference
1337 and then Is_Access_Type
(Etype
(ItemT
))
1338 and then Is_Entity_Name
(Prefix
(ItemT
))
1339 and then Is_Type
(Entity
(Prefix
(ItemT
)))
1344 -- If the expressions for the discriminants are identical
1345 -- and it is side-effect free (for now just an entity),
1346 -- this may be a shared constraint, e.g. from a subtype
1347 -- without a constraint introduced as a generic actual.
1348 -- Examine other discriminants if any.
1351 and then Is_Entity_Name
(ItemS
)
1355 elsif not Is_OK_Static_Expression
(ItemS
)
1356 or else not Is_OK_Static_Expression
(ItemT
)
1360 elsif Expr_Value
(ItemS
) /= Expr_Value
(ItemT
) then
1361 if Do_Access
then -- needs run-time check.
1364 Apply_Compile_Time_Constraint_Error
1365 (N
, "incorrect value for discriminant&?",
1366 CE_Discriminant_Check_Failed
, Ent
=> Discr
);
1373 Next_Discriminant
(Discr
);
1382 -- Here we need a discriminant check. First build the expression
1383 -- for the comparisons of the discriminants:
1385 -- (n.disc1 /= typ.disc1) or else
1386 -- (n.disc2 /= typ.disc2) or else
1388 -- (n.discn /= typ.discn)
1390 Cond
:= Build_Discriminant_Checks
(N
, T_Typ
);
1392 -- If Lhs is set and is a parameter, then the condition is
1393 -- guarded by: lhs'constrained and then (condition built above)
1395 if Present
(Param_Entity
(Lhs
)) then
1399 Make_Attribute_Reference
(Loc
,
1400 Prefix
=> New_Occurrence_Of
(Param_Entity
(Lhs
), Loc
),
1401 Attribute_Name
=> Name_Constrained
),
1402 Right_Opnd
=> Cond
);
1406 Cond
:= Guard_Access
(Cond
, Loc
, N
);
1410 Make_Raise_Constraint_Error
(Loc
,
1412 Reason
=> CE_Discriminant_Check_Failed
));
1413 end Apply_Discriminant_Check
;
1415 ------------------------
1416 -- Apply_Divide_Check --
1417 ------------------------
1419 procedure Apply_Divide_Check
(N
: Node_Id
) is
1420 Loc
: constant Source_Ptr
:= Sloc
(N
);
1421 Typ
: constant Entity_Id
:= Etype
(N
);
1422 Left
: constant Node_Id
:= Left_Opnd
(N
);
1423 Right
: constant Node_Id
:= Right_Opnd
(N
);
1433 pragma Warnings
(Off
, Lhi
);
1434 -- Don't actually use this value
1438 and then not Backend_Divide_Checks_On_Target
1439 and then Check_Needed
(Right
, Division_Check
)
1441 Determine_Range
(Right
, ROK
, Rlo
, Rhi
, Assume_Valid
=> True);
1443 -- See if division by zero possible, and if so generate test. This
1444 -- part of the test is not controlled by the -gnato switch.
1446 if Do_Division_Check
(N
) then
1447 if (not ROK
) or else (Rlo
<= 0 and then 0 <= Rhi
) then
1449 Make_Raise_Constraint_Error
(Loc
,
1452 Left_Opnd
=> Duplicate_Subexpr_Move_Checks
(Right
),
1453 Right_Opnd
=> Make_Integer_Literal
(Loc
, 0)),
1454 Reason
=> CE_Divide_By_Zero
));
1458 -- Test for extremely annoying case of xxx'First divided by -1
1460 if Do_Overflow_Check
(N
) then
1461 if Nkind
(N
) = N_Op_Divide
1462 and then Is_Signed_Integer_Type
(Typ
)
1464 Determine_Range
(Left
, LOK
, Llo
, Lhi
, Assume_Valid
=> True);
1465 LLB
:= Expr_Value
(Type_Low_Bound
(Base_Type
(Typ
)));
1467 if ((not ROK
) or else (Rlo
<= (-1) and then (-1) <= Rhi
))
1469 ((not LOK
) or else (Llo
= LLB
))
1472 Make_Raise_Constraint_Error
(Loc
,
1478 Duplicate_Subexpr_Move_Checks
(Left
),
1479 Right_Opnd
=> Make_Integer_Literal
(Loc
, LLB
)),
1483 Duplicate_Subexpr
(Right
),
1485 Make_Integer_Literal
(Loc
, -1))),
1486 Reason
=> CE_Overflow_Check_Failed
));
1491 end Apply_Divide_Check
;
1493 ----------------------------------
1494 -- Apply_Float_Conversion_Check --
1495 ----------------------------------
1497 -- Let F and I be the source and target types of the conversion. The RM
1498 -- specifies that a floating-point value X is rounded to the nearest
1499 -- integer, with halfway cases being rounded away from zero. The rounded
1500 -- value of X is checked against I'Range.
1502 -- The catch in the above paragraph is that there is no good way to know
1503 -- whether the round-to-integer operation resulted in overflow. A remedy is
1504 -- to perform a range check in the floating-point domain instead, however:
1506 -- (1) The bounds may not be known at compile time
1507 -- (2) The check must take into account rounding or truncation.
1508 -- (3) The range of type I may not be exactly representable in F.
1509 -- (4) For the rounding case, The end-points I'First - 0.5 and
1510 -- I'Last + 0.5 may or may not be in range, depending on the
1511 -- sign of I'First and I'Last.
1512 -- (5) X may be a NaN, which will fail any comparison
1514 -- The following steps correctly convert X with rounding:
1516 -- (1) If either I'First or I'Last is not known at compile time, use
1517 -- I'Base instead of I in the next three steps and perform a
1518 -- regular range check against I'Range after conversion.
1519 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1520 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1521 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1522 -- In other words, take one of the closest floating-point numbers
1523 -- (which is an integer value) to I'First, and see if it is in
1525 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1526 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1527 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1528 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1529 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1531 -- For the truncating case, replace steps (2) and (3) as follows:
1532 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1533 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1535 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1536 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1539 procedure Apply_Float_Conversion_Check
1541 Target_Typ
: Entity_Id
)
1543 LB
: constant Node_Id
:= Type_Low_Bound
(Target_Typ
);
1544 HB
: constant Node_Id
:= Type_High_Bound
(Target_Typ
);
1545 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
1546 Expr_Type
: constant Entity_Id
:= Base_Type
(Etype
(Ck_Node
));
1547 Target_Base
: constant Entity_Id
:=
1548 Implementation_Base_Type
(Target_Typ
);
1550 Par
: constant Node_Id
:= Parent
(Ck_Node
);
1551 pragma Assert
(Nkind
(Par
) = N_Type_Conversion
);
1552 -- Parent of check node, must be a type conversion
1554 Truncate
: constant Boolean := Float_Truncate
(Par
);
1555 Max_Bound
: constant Uint
:=
1557 (Machine_Radix
(Expr_Type
),
1558 Machine_Mantissa
(Expr_Type
) - 1) - 1;
1560 -- Largest bound, so bound plus or minus half is a machine number of F
1562 Ifirst
, Ilast
: Uint
;
1563 -- Bounds of integer type
1566 -- Bounds to check in floating-point domain
1568 Lo_OK
, Hi_OK
: Boolean;
1569 -- True iff Lo resp. Hi belongs to I'Range
1571 Lo_Chk
, Hi_Chk
: Node_Id
;
1572 -- Expressions that are False iff check fails
1574 Reason
: RT_Exception_Code
;
1577 if not Compile_Time_Known_Value
(LB
)
1578 or not Compile_Time_Known_Value
(HB
)
1581 -- First check that the value falls in the range of the base type,
1582 -- to prevent overflow during conversion and then perform a
1583 -- regular range check against the (dynamic) bounds.
1585 pragma Assert
(Target_Base
/= Target_Typ
);
1587 Temp
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', Par
);
1590 Apply_Float_Conversion_Check
(Ck_Node
, Target_Base
);
1591 Set_Etype
(Temp
, Target_Base
);
1593 Insert_Action
(Parent
(Par
),
1594 Make_Object_Declaration
(Loc
,
1595 Defining_Identifier
=> Temp
,
1596 Object_Definition
=> New_Occurrence_Of
(Target_Typ
, Loc
),
1597 Expression
=> New_Copy_Tree
(Par
)),
1598 Suppress
=> All_Checks
);
1601 Make_Raise_Constraint_Error
(Loc
,
1604 Left_Opnd
=> New_Occurrence_Of
(Temp
, Loc
),
1605 Right_Opnd
=> New_Occurrence_Of
(Target_Typ
, Loc
)),
1606 Reason
=> CE_Range_Check_Failed
));
1607 Rewrite
(Par
, New_Occurrence_Of
(Temp
, Loc
));
1613 -- Get the (static) bounds of the target type
1615 Ifirst
:= Expr_Value
(LB
);
1616 Ilast
:= Expr_Value
(HB
);
1618 -- A simple optimization: if the expression is a universal literal,
1619 -- we can do the comparison with the bounds and the conversion to
1620 -- an integer type statically. The range checks are unchanged.
1622 if Nkind
(Ck_Node
) = N_Real_Literal
1623 and then Etype
(Ck_Node
) = Universal_Real
1624 and then Is_Integer_Type
(Target_Typ
)
1625 and then Nkind
(Parent
(Ck_Node
)) = N_Type_Conversion
1628 Int_Val
: constant Uint
:= UR_To_Uint
(Realval
(Ck_Node
));
1631 if Int_Val
<= Ilast
and then Int_Val
>= Ifirst
then
1633 -- Conversion is safe
1635 Rewrite
(Parent
(Ck_Node
),
1636 Make_Integer_Literal
(Loc
, UI_To_Int
(Int_Val
)));
1637 Analyze_And_Resolve
(Parent
(Ck_Node
), Target_Typ
);
1643 -- Check against lower bound
1645 if Truncate
and then Ifirst
> 0 then
1646 Lo
:= Pred
(Expr_Type
, UR_From_Uint
(Ifirst
));
1650 Lo
:= Succ
(Expr_Type
, UR_From_Uint
(Ifirst
- 1));
1653 elsif abs (Ifirst
) < Max_Bound
then
1654 Lo
:= UR_From_Uint
(Ifirst
) - Ureal_Half
;
1655 Lo_OK
:= (Ifirst
> 0);
1658 Lo
:= Machine
(Expr_Type
, UR_From_Uint
(Ifirst
), Round_Even
, Ck_Node
);
1659 Lo_OK
:= (Lo
>= UR_From_Uint
(Ifirst
));
1664 -- Lo_Chk := (X >= Lo)
1666 Lo_Chk
:= Make_Op_Ge
(Loc
,
1667 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
1668 Right_Opnd
=> Make_Real_Literal
(Loc
, Lo
));
1671 -- Lo_Chk := (X > Lo)
1673 Lo_Chk
:= Make_Op_Gt
(Loc
,
1674 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
1675 Right_Opnd
=> Make_Real_Literal
(Loc
, Lo
));
1678 -- Check against higher bound
1680 if Truncate
and then Ilast
< 0 then
1681 Hi
:= Succ
(Expr_Type
, UR_From_Uint
(Ilast
));
1685 Hi
:= Pred
(Expr_Type
, UR_From_Uint
(Ilast
+ 1));
1688 elsif abs (Ilast
) < Max_Bound
then
1689 Hi
:= UR_From_Uint
(Ilast
) + Ureal_Half
;
1690 Hi_OK
:= (Ilast
< 0);
1692 Hi
:= Machine
(Expr_Type
, UR_From_Uint
(Ilast
), Round_Even
, Ck_Node
);
1693 Hi_OK
:= (Hi
<= UR_From_Uint
(Ilast
));
1698 -- Hi_Chk := (X <= Hi)
1700 Hi_Chk
:= Make_Op_Le
(Loc
,
1701 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
1702 Right_Opnd
=> Make_Real_Literal
(Loc
, Hi
));
1705 -- Hi_Chk := (X < Hi)
1707 Hi_Chk
:= Make_Op_Lt
(Loc
,
1708 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
1709 Right_Opnd
=> Make_Real_Literal
(Loc
, Hi
));
1712 -- If the bounds of the target type are the same as those of the base
1713 -- type, the check is an overflow check as a range check is not
1714 -- performed in these cases.
1716 if Expr_Value
(Type_Low_Bound
(Target_Base
)) = Ifirst
1717 and then Expr_Value
(Type_High_Bound
(Target_Base
)) = Ilast
1719 Reason
:= CE_Overflow_Check_Failed
;
1721 Reason
:= CE_Range_Check_Failed
;
1724 -- Raise CE if either conditions does not hold
1726 Insert_Action
(Ck_Node
,
1727 Make_Raise_Constraint_Error
(Loc
,
1728 Condition
=> Make_Op_Not
(Loc
, Make_And_Then
(Loc
, Lo_Chk
, Hi_Chk
)),
1730 end Apply_Float_Conversion_Check
;
1732 ------------------------
1733 -- Apply_Length_Check --
1734 ------------------------
1736 procedure Apply_Length_Check
1738 Target_Typ
: Entity_Id
;
1739 Source_Typ
: Entity_Id
:= Empty
)
1742 Apply_Selected_Length_Checks
1743 (Ck_Node
, Target_Typ
, Source_Typ
, Do_Static
=> False);
1744 end Apply_Length_Check
;
1746 -----------------------
1747 -- Apply_Range_Check --
1748 -----------------------
1750 procedure Apply_Range_Check
1752 Target_Typ
: Entity_Id
;
1753 Source_Typ
: Entity_Id
:= Empty
)
1756 Apply_Selected_Range_Checks
1757 (Ck_Node
, Target_Typ
, Source_Typ
, Do_Static
=> False);
1758 end Apply_Range_Check
;
1760 ------------------------------
1761 -- Apply_Scalar_Range_Check --
1762 ------------------------------
1764 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1765 -- off if it is already set on.
1767 procedure Apply_Scalar_Range_Check
1769 Target_Typ
: Entity_Id
;
1770 Source_Typ
: Entity_Id
:= Empty
;
1771 Fixed_Int
: Boolean := False)
1773 Parnt
: constant Node_Id
:= Parent
(Expr
);
1775 Arr
: Node_Id
:= Empty
; -- initialize to prevent warning
1776 Arr_Typ
: Entity_Id
:= Empty
; -- initialize to prevent warning
1779 Is_Subscr_Ref
: Boolean;
1780 -- Set true if Expr is a subscript
1782 Is_Unconstrained_Subscr_Ref
: Boolean;
1783 -- Set true if Expr is a subscript of an unconstrained array. In this
1784 -- case we do not attempt to do an analysis of the value against the
1785 -- range of the subscript, since we don't know the actual subtype.
1788 -- Set to True if Expr should be regarded as a real value even though
1789 -- the type of Expr might be discrete.
1791 procedure Bad_Value
;
1792 -- Procedure called if value is determined to be out of range
1798 procedure Bad_Value
is
1800 Apply_Compile_Time_Constraint_Error
1801 (Expr
, "value not in range of}?", CE_Range_Check_Failed
,
1806 -- Start of processing for Apply_Scalar_Range_Check
1809 -- Return if check obviously not needed
1812 -- Not needed inside generic
1816 -- Not needed if previous error
1818 or else Target_Typ
= Any_Type
1819 or else Nkind
(Expr
) = N_Error
1821 -- Not needed for non-scalar type
1823 or else not Is_Scalar_Type
(Target_Typ
)
1825 -- Not needed if we know node raises CE already
1827 or else Raises_Constraint_Error
(Expr
)
1832 -- Now, see if checks are suppressed
1835 Is_List_Member
(Expr
) and then Nkind
(Parnt
) = N_Indexed_Component
;
1837 if Is_Subscr_Ref
then
1838 Arr
:= Prefix
(Parnt
);
1839 Arr_Typ
:= Get_Actual_Subtype_If_Available
(Arr
);
1842 if not Do_Range_Check
(Expr
) then
1844 -- Subscript reference. Check for Index_Checks suppressed
1846 if Is_Subscr_Ref
then
1848 -- Check array type and its base type
1850 if Index_Checks_Suppressed
(Arr_Typ
)
1851 or else Index_Checks_Suppressed
(Base_Type
(Arr_Typ
))
1855 -- Check array itself if it is an entity name
1857 elsif Is_Entity_Name
(Arr
)
1858 and then Index_Checks_Suppressed
(Entity
(Arr
))
1862 -- Check expression itself if it is an entity name
1864 elsif Is_Entity_Name
(Expr
)
1865 and then Index_Checks_Suppressed
(Entity
(Expr
))
1870 -- All other cases, check for Range_Checks suppressed
1873 -- Check target type and its base type
1875 if Range_Checks_Suppressed
(Target_Typ
)
1876 or else Range_Checks_Suppressed
(Base_Type
(Target_Typ
))
1880 -- Check expression itself if it is an entity name
1882 elsif Is_Entity_Name
(Expr
)
1883 and then Range_Checks_Suppressed
(Entity
(Expr
))
1887 -- If Expr is part of an assignment statement, then check left
1888 -- side of assignment if it is an entity name.
1890 elsif Nkind
(Parnt
) = N_Assignment_Statement
1891 and then Is_Entity_Name
(Name
(Parnt
))
1892 and then Range_Checks_Suppressed
(Entity
(Name
(Parnt
)))
1899 -- Do not set range checks if they are killed
1901 if Nkind
(Expr
) = N_Unchecked_Type_Conversion
1902 and then Kill_Range_Check
(Expr
)
1907 -- Do not set range checks for any values from System.Scalar_Values
1908 -- since the whole idea of such values is to avoid checking them!
1910 if Is_Entity_Name
(Expr
)
1911 and then Is_RTU
(Scope
(Entity
(Expr
)), System_Scalar_Values
)
1916 -- Now see if we need a check
1918 if No
(Source_Typ
) then
1919 S_Typ
:= Etype
(Expr
);
1921 S_Typ
:= Source_Typ
;
1924 if not Is_Scalar_Type
(S_Typ
) or else S_Typ
= Any_Type
then
1928 Is_Unconstrained_Subscr_Ref
:=
1929 Is_Subscr_Ref
and then not Is_Constrained
(Arr_Typ
);
1931 -- Always do a range check if the source type includes infinities and
1932 -- the target type does not include infinities. We do not do this if
1933 -- range checks are killed.
1935 if Is_Floating_Point_Type
(S_Typ
)
1936 and then Has_Infinities
(S_Typ
)
1937 and then not Has_Infinities
(Target_Typ
)
1939 Enable_Range_Check
(Expr
);
1942 -- Return if we know expression is definitely in the range of the target
1943 -- type as determined by Determine_Range. Right now we only do this for
1944 -- discrete types, and not fixed-point or floating-point types.
1946 -- The additional less-precise tests below catch these cases
1948 -- Note: skip this if we are given a source_typ, since the point of
1949 -- supplying a Source_Typ is to stop us looking at the expression.
1950 -- We could sharpen this test to be out parameters only ???
1952 if Is_Discrete_Type
(Target_Typ
)
1953 and then Is_Discrete_Type
(Etype
(Expr
))
1954 and then not Is_Unconstrained_Subscr_Ref
1955 and then No
(Source_Typ
)
1958 Tlo
: constant Node_Id
:= Type_Low_Bound
(Target_Typ
);
1959 Thi
: constant Node_Id
:= Type_High_Bound
(Target_Typ
);
1964 if Compile_Time_Known_Value
(Tlo
)
1965 and then Compile_Time_Known_Value
(Thi
)
1968 Lov
: constant Uint
:= Expr_Value
(Tlo
);
1969 Hiv
: constant Uint
:= Expr_Value
(Thi
);
1972 -- If range is null, we for sure have a constraint error
1973 -- (we don't even need to look at the value involved,
1974 -- since all possible values will raise CE).
1981 -- Otherwise determine range of value
1983 Determine_Range
(Expr
, OK
, Lo
, Hi
, Assume_Valid
=> True);
1987 -- If definitely in range, all OK
1989 if Lo
>= Lov
and then Hi
<= Hiv
then
1992 -- If definitely not in range, warn
1994 elsif Lov
> Hi
or else Hiv
< Lo
then
1998 -- Otherwise we don't know
2010 Is_Floating_Point_Type
(S_Typ
)
2011 or else (Is_Fixed_Point_Type
(S_Typ
) and then not Fixed_Int
);
2013 -- Check if we can determine at compile time whether Expr is in the
2014 -- range of the target type. Note that if S_Typ is within the bounds
2015 -- of Target_Typ then this must be the case. This check is meaningful
2016 -- only if this is not a conversion between integer and real types.
2018 if not Is_Unconstrained_Subscr_Ref
2020 Is_Discrete_Type
(S_Typ
) = Is_Discrete_Type
(Target_Typ
)
2022 (In_Subrange_Of
(S_Typ
, Target_Typ
, Fixed_Int
)
2024 Is_In_Range
(Expr
, Target_Typ
,
2025 Assume_Valid
=> True,
2026 Fixed_Int
=> Fixed_Int
,
2027 Int_Real
=> Int_Real
))
2031 elsif Is_Out_Of_Range
(Expr
, Target_Typ
,
2032 Assume_Valid
=> True,
2033 Fixed_Int
=> Fixed_Int
,
2034 Int_Real
=> Int_Real
)
2039 -- In the floating-point case, we only do range checks if the type is
2040 -- constrained. We definitely do NOT want range checks for unconstrained
2041 -- types, since we want to have infinities
2043 elsif Is_Floating_Point_Type
(S_Typ
) then
2044 if Is_Constrained
(S_Typ
) then
2045 Enable_Range_Check
(Expr
);
2048 -- For all other cases we enable a range check unconditionally
2051 Enable_Range_Check
(Expr
);
2054 end Apply_Scalar_Range_Check
;
2056 ----------------------------------
2057 -- Apply_Selected_Length_Checks --
2058 ----------------------------------
2060 procedure Apply_Selected_Length_Checks
2062 Target_Typ
: Entity_Id
;
2063 Source_Typ
: Entity_Id
;
2064 Do_Static
: Boolean)
2067 R_Result
: Check_Result
;
2070 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
2071 Checks_On
: constant Boolean :=
2072 (not Index_Checks_Suppressed
(Target_Typ
))
2074 (not Length_Checks_Suppressed
(Target_Typ
));
2077 if not Expander_Active
then
2082 Selected_Length_Checks
(Ck_Node
, Target_Typ
, Source_Typ
, Empty
);
2084 for J
in 1 .. 2 loop
2085 R_Cno
:= R_Result
(J
);
2086 exit when No
(R_Cno
);
2088 -- A length check may mention an Itype which is attached to a
2089 -- subsequent node. At the top level in a package this can cause
2090 -- an order-of-elaboration problem, so we make sure that the itype
2091 -- is referenced now.
2093 if Ekind
(Current_Scope
) = E_Package
2094 and then Is_Compilation_Unit
(Current_Scope
)
2096 Ensure_Defined
(Target_Typ
, Ck_Node
);
2098 if Present
(Source_Typ
) then
2099 Ensure_Defined
(Source_Typ
, Ck_Node
);
2101 elsif Is_Itype
(Etype
(Ck_Node
)) then
2102 Ensure_Defined
(Etype
(Ck_Node
), Ck_Node
);
2106 -- If the item is a conditional raise of constraint error, then have
2107 -- a look at what check is being performed and ???
2109 if Nkind
(R_Cno
) = N_Raise_Constraint_Error
2110 and then Present
(Condition
(R_Cno
))
2112 Cond
:= Condition
(R_Cno
);
2114 -- Case where node does not now have a dynamic check
2116 if not Has_Dynamic_Length_Check
(Ck_Node
) then
2118 -- If checks are on, just insert the check
2121 Insert_Action
(Ck_Node
, R_Cno
);
2123 if not Do_Static
then
2124 Set_Has_Dynamic_Length_Check
(Ck_Node
);
2127 -- If checks are off, then analyze the length check after
2128 -- temporarily attaching it to the tree in case the relevant
2129 -- condition can be evaluted at compile time. We still want a
2130 -- compile time warning in this case.
2133 Set_Parent
(R_Cno
, Ck_Node
);
2138 -- Output a warning if the condition is known to be True
2140 if Is_Entity_Name
(Cond
)
2141 and then Entity
(Cond
) = Standard_True
2143 Apply_Compile_Time_Constraint_Error
2144 (Ck_Node
, "wrong length for array of}?",
2145 CE_Length_Check_Failed
,
2149 -- If we were only doing a static check, or if checks are not
2150 -- on, then we want to delete the check, since it is not needed.
2151 -- We do this by replacing the if statement by a null statement
2153 elsif Do_Static
or else not Checks_On
then
2154 Remove_Warning_Messages
(R_Cno
);
2155 Rewrite
(R_Cno
, Make_Null_Statement
(Loc
));
2159 Install_Static_Check
(R_Cno
, Loc
);
2162 end Apply_Selected_Length_Checks
;
2164 ---------------------------------
2165 -- Apply_Selected_Range_Checks --
2166 ---------------------------------
2168 procedure Apply_Selected_Range_Checks
2170 Target_Typ
: Entity_Id
;
2171 Source_Typ
: Entity_Id
;
2172 Do_Static
: Boolean)
2175 R_Result
: Check_Result
;
2178 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
2179 Checks_On
: constant Boolean :=
2180 (not Index_Checks_Suppressed
(Target_Typ
))
2182 (not Range_Checks_Suppressed
(Target_Typ
));
2185 if not Expander_Active
or else not Checks_On
then
2190 Selected_Range_Checks
(Ck_Node
, Target_Typ
, Source_Typ
, Empty
);
2192 for J
in 1 .. 2 loop
2194 R_Cno
:= R_Result
(J
);
2195 exit when No
(R_Cno
);
2197 -- If the item is a conditional raise of constraint error, then have
2198 -- a look at what check is being performed and ???
2200 if Nkind
(R_Cno
) = N_Raise_Constraint_Error
2201 and then Present
(Condition
(R_Cno
))
2203 Cond
:= Condition
(R_Cno
);
2205 if not Has_Dynamic_Range_Check
(Ck_Node
) then
2206 Insert_Action
(Ck_Node
, R_Cno
);
2208 if not Do_Static
then
2209 Set_Has_Dynamic_Range_Check
(Ck_Node
);
2213 -- Output a warning if the condition is known to be True
2215 if Is_Entity_Name
(Cond
)
2216 and then Entity
(Cond
) = Standard_True
2218 -- Since an N_Range is technically not an expression, we have
2219 -- to set one of the bounds to C_E and then just flag the
2220 -- N_Range. The warning message will point to the lower bound
2221 -- and complain about a range, which seems OK.
2223 if Nkind
(Ck_Node
) = N_Range
then
2224 Apply_Compile_Time_Constraint_Error
2225 (Low_Bound
(Ck_Node
), "static range out of bounds of}?",
2226 CE_Range_Check_Failed
,
2230 Set_Raises_Constraint_Error
(Ck_Node
);
2233 Apply_Compile_Time_Constraint_Error
2234 (Ck_Node
, "static value out of range of}?",
2235 CE_Range_Check_Failed
,
2240 -- If we were only doing a static check, or if checks are not
2241 -- on, then we want to delete the check, since it is not needed.
2242 -- We do this by replacing the if statement by a null statement
2244 elsif Do_Static
or else not Checks_On
then
2245 Remove_Warning_Messages
(R_Cno
);
2246 Rewrite
(R_Cno
, Make_Null_Statement
(Loc
));
2250 Install_Static_Check
(R_Cno
, Loc
);
2253 end Apply_Selected_Range_Checks
;
2255 -------------------------------
2256 -- Apply_Static_Length_Check --
2257 -------------------------------
2259 procedure Apply_Static_Length_Check
2261 Target_Typ
: Entity_Id
;
2262 Source_Typ
: Entity_Id
:= Empty
)
2265 Apply_Selected_Length_Checks
2266 (Expr
, Target_Typ
, Source_Typ
, Do_Static
=> True);
2267 end Apply_Static_Length_Check
;
2269 -------------------------------------
2270 -- Apply_Subscript_Validity_Checks --
2271 -------------------------------------
2273 procedure Apply_Subscript_Validity_Checks
(Expr
: Node_Id
) is
2277 pragma Assert
(Nkind
(Expr
) = N_Indexed_Component
);
2279 -- Loop through subscripts
2281 Sub
:= First
(Expressions
(Expr
));
2282 while Present
(Sub
) loop
2284 -- Check one subscript. Note that we do not worry about enumeration
2285 -- type with holes, since we will convert the value to a Pos value
2286 -- for the subscript, and that convert will do the necessary validity
2289 Ensure_Valid
(Sub
, Holes_OK
=> True);
2291 -- Move to next subscript
2295 end Apply_Subscript_Validity_Checks
;
2297 ----------------------------------
2298 -- Apply_Type_Conversion_Checks --
2299 ----------------------------------
2301 procedure Apply_Type_Conversion_Checks
(N
: Node_Id
) is
2302 Target_Type
: constant Entity_Id
:= Etype
(N
);
2303 Target_Base
: constant Entity_Id
:= Base_Type
(Target_Type
);
2304 Expr
: constant Node_Id
:= Expression
(N
);
2305 Expr_Type
: constant Entity_Id
:= Etype
(Expr
);
2308 if Inside_A_Generic
then
2311 -- Skip these checks if serious errors detected, there are some nasty
2312 -- situations of incomplete trees that blow things up.
2314 elsif Serious_Errors_Detected
> 0 then
2317 -- Scalar type conversions of the form Target_Type (Expr) require a
2318 -- range check if we cannot be sure that Expr is in the base type of
2319 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2320 -- are not quite the same condition from an implementation point of
2321 -- view, but clearly the second includes the first.
2323 elsif Is_Scalar_Type
(Target_Type
) then
2325 Conv_OK
: constant Boolean := Conversion_OK
(N
);
2326 -- If the Conversion_OK flag on the type conversion is set and no
2327 -- floating point type is involved in the type conversion then
2328 -- fixed point values must be read as integral values.
2330 Float_To_Int
: constant Boolean :=
2331 Is_Floating_Point_Type
(Expr_Type
)
2332 and then Is_Integer_Type
(Target_Type
);
2335 if not Overflow_Checks_Suppressed
(Target_Base
)
2337 In_Subrange_Of
(Expr_Type
, Target_Base
, Fixed_Int
=> Conv_OK
)
2338 and then not Float_To_Int
2340 Activate_Overflow_Check
(N
);
2343 if not Range_Checks_Suppressed
(Target_Type
)
2344 and then not Range_Checks_Suppressed
(Expr_Type
)
2346 if Float_To_Int
then
2347 Apply_Float_Conversion_Check
(Expr
, Target_Type
);
2349 Apply_Scalar_Range_Check
2350 (Expr
, Target_Type
, Fixed_Int
=> Conv_OK
);
2355 elsif Comes_From_Source
(N
)
2356 and then not Discriminant_Checks_Suppressed
(Target_Type
)
2357 and then Is_Record_Type
(Target_Type
)
2358 and then Is_Derived_Type
(Target_Type
)
2359 and then not Is_Tagged_Type
(Target_Type
)
2360 and then not Is_Constrained
(Target_Type
)
2361 and then Present
(Stored_Constraint
(Target_Type
))
2363 -- An unconstrained derived type may have inherited discriminant
2364 -- Build an actual discriminant constraint list using the stored
2365 -- constraint, to verify that the expression of the parent type
2366 -- satisfies the constraints imposed by the (unconstrained!)
2367 -- derived type. This applies to value conversions, not to view
2368 -- conversions of tagged types.
2371 Loc
: constant Source_Ptr
:= Sloc
(N
);
2373 Constraint
: Elmt_Id
;
2374 Discr_Value
: Node_Id
;
2377 New_Constraints
: constant Elist_Id
:= New_Elmt_List
;
2378 Old_Constraints
: constant Elist_Id
:=
2379 Discriminant_Constraint
(Expr_Type
);
2382 Constraint
:= First_Elmt
(Stored_Constraint
(Target_Type
));
2383 while Present
(Constraint
) loop
2384 Discr_Value
:= Node
(Constraint
);
2386 if Is_Entity_Name
(Discr_Value
)
2387 and then Ekind
(Entity
(Discr_Value
)) = E_Discriminant
2389 Discr
:= Corresponding_Discriminant
(Entity
(Discr_Value
));
2392 and then Scope
(Discr
) = Base_Type
(Expr_Type
)
2394 -- Parent is constrained by new discriminant. Obtain
2395 -- Value of original discriminant in expression. If the
2396 -- new discriminant has been used to constrain more than
2397 -- one of the stored discriminants, this will provide the
2398 -- required consistency check.
2401 Make_Selected_Component
(Loc
,
2403 Duplicate_Subexpr_No_Checks
2404 (Expr
, Name_Req
=> True),
2406 Make_Identifier
(Loc
, Chars
(Discr
))),
2410 -- Discriminant of more remote ancestor ???
2415 -- Derived type definition has an explicit value for this
2416 -- stored discriminant.
2420 (Duplicate_Subexpr_No_Checks
(Discr_Value
),
2424 Next_Elmt
(Constraint
);
2427 -- Use the unconstrained expression type to retrieve the
2428 -- discriminants of the parent, and apply momentarily the
2429 -- discriminant constraint synthesized above.
2431 Set_Discriminant_Constraint
(Expr_Type
, New_Constraints
);
2432 Cond
:= Build_Discriminant_Checks
(Expr
, Expr_Type
);
2433 Set_Discriminant_Constraint
(Expr_Type
, Old_Constraints
);
2436 Make_Raise_Constraint_Error
(Loc
,
2438 Reason
=> CE_Discriminant_Check_Failed
));
2441 -- For arrays, conversions are applied during expansion, to take into
2442 -- accounts changes of representation. The checks become range checks on
2443 -- the base type or length checks on the subtype, depending on whether
2444 -- the target type is unconstrained or constrained.
2449 end Apply_Type_Conversion_Checks
;
2451 ----------------------------------------------
2452 -- Apply_Universal_Integer_Attribute_Checks --
2453 ----------------------------------------------
2455 procedure Apply_Universal_Integer_Attribute_Checks
(N
: Node_Id
) is
2456 Loc
: constant Source_Ptr
:= Sloc
(N
);
2457 Typ
: constant Entity_Id
:= Etype
(N
);
2460 if Inside_A_Generic
then
2463 -- Nothing to do if checks are suppressed
2465 elsif Range_Checks_Suppressed
(Typ
)
2466 and then Overflow_Checks_Suppressed
(Typ
)
2470 -- Nothing to do if the attribute does not come from source. The
2471 -- internal attributes we generate of this type do not need checks,
2472 -- and furthermore the attempt to check them causes some circular
2473 -- elaboration orders when dealing with packed types.
2475 elsif not Comes_From_Source
(N
) then
2478 -- If the prefix is a selected component that depends on a discriminant
2479 -- the check may improperly expose a discriminant instead of using
2480 -- the bounds of the object itself. Set the type of the attribute to
2481 -- the base type of the context, so that a check will be imposed when
2482 -- needed (e.g. if the node appears as an index).
2484 elsif Nkind
(Prefix
(N
)) = N_Selected_Component
2485 and then Ekind
(Typ
) = E_Signed_Integer_Subtype
2486 and then Depends_On_Discriminant
(Scalar_Range
(Typ
))
2488 Set_Etype
(N
, Base_Type
(Typ
));
2490 -- Otherwise, replace the attribute node with a type conversion node
2491 -- whose expression is the attribute, retyped to universal integer, and
2492 -- whose subtype mark is the target type. The call to analyze this
2493 -- conversion will set range and overflow checks as required for proper
2494 -- detection of an out of range value.
2497 Set_Etype
(N
, Universal_Integer
);
2498 Set_Analyzed
(N
, True);
2501 Make_Type_Conversion
(Loc
,
2502 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
2503 Expression
=> Relocate_Node
(N
)));
2505 Analyze_And_Resolve
(N
, Typ
);
2508 end Apply_Universal_Integer_Attribute_Checks
;
2510 -------------------------------
2511 -- Build_Discriminant_Checks --
2512 -------------------------------
2514 function Build_Discriminant_Checks
2516 T_Typ
: Entity_Id
) return Node_Id
2518 Loc
: constant Source_Ptr
:= Sloc
(N
);
2521 Disc_Ent
: Entity_Id
;
2525 function Aggregate_Discriminant_Val
(Disc
: Entity_Id
) return Node_Id
;
2527 ----------------------------------
2528 -- Aggregate_Discriminant_Value --
2529 ----------------------------------
2531 function Aggregate_Discriminant_Val
(Disc
: Entity_Id
) return Node_Id
is
2535 -- The aggregate has been normalized with named associations. We use
2536 -- the Chars field to locate the discriminant to take into account
2537 -- discriminants in derived types, which carry the same name as those
2540 Assoc
:= First
(Component_Associations
(N
));
2541 while Present
(Assoc
) loop
2542 if Chars
(First
(Choices
(Assoc
))) = Chars
(Disc
) then
2543 return Expression
(Assoc
);
2549 -- Discriminant must have been found in the loop above
2551 raise Program_Error
;
2552 end Aggregate_Discriminant_Val
;
2554 -- Start of processing for Build_Discriminant_Checks
2557 -- Loop through discriminants evolving the condition
2560 Disc
:= First_Elmt
(Discriminant_Constraint
(T_Typ
));
2562 -- For a fully private type, use the discriminants of the parent type
2564 if Is_Private_Type
(T_Typ
)
2565 and then No
(Full_View
(T_Typ
))
2567 Disc_Ent
:= First_Discriminant
(Etype
(Base_Type
(T_Typ
)));
2569 Disc_Ent
:= First_Discriminant
(T_Typ
);
2572 while Present
(Disc
) loop
2573 Dval
:= Node
(Disc
);
2575 if Nkind
(Dval
) = N_Identifier
2576 and then Ekind
(Entity
(Dval
)) = E_Discriminant
2578 Dval
:= New_Occurrence_Of
(Discriminal
(Entity
(Dval
)), Loc
);
2580 Dval
:= Duplicate_Subexpr_No_Checks
(Dval
);
2583 -- If we have an Unchecked_Union node, we can infer the discriminants
2586 if Is_Unchecked_Union
(Base_Type
(T_Typ
)) then
2588 Get_Discriminant_Value
(
2589 First_Discriminant
(T_Typ
),
2591 Stored_Constraint
(T_Typ
)));
2593 elsif Nkind
(N
) = N_Aggregate
then
2595 Duplicate_Subexpr_No_Checks
2596 (Aggregate_Discriminant_Val
(Disc_Ent
));
2600 Make_Selected_Component
(Loc
,
2602 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
2604 Make_Identifier
(Loc
, Chars
(Disc_Ent
)));
2606 Set_Is_In_Discriminant_Check
(Dref
);
2609 Evolve_Or_Else
(Cond
,
2612 Right_Opnd
=> Dval
));
2615 Next_Discriminant
(Disc_Ent
);
2619 end Build_Discriminant_Checks
;
2625 function Check_Needed
(Nod
: Node_Id
; Check
: Check_Type
) return Boolean is
2633 -- Always check if not simple entity
2635 if Nkind
(Nod
) not in N_Has_Entity
2636 or else not Comes_From_Source
(Nod
)
2641 -- Look up tree for short circuit
2648 -- Done if out of subexpression (note that we allow generated stuff
2649 -- such as itype declarations in this context, to keep the loop going
2650 -- since we may well have generated such stuff in complex situations.
2651 -- Also done if no parent (probably an error condition, but no point
2652 -- in behaving nasty if we find it!)
2655 or else (K
not in N_Subexpr
and then Comes_From_Source
(P
))
2659 -- Or/Or Else case, where test is part of the right operand, or is
2660 -- part of one of the actions associated with the right operand, and
2661 -- the left operand is an equality test.
2663 elsif K
= N_Op_Or
then
2664 exit when N
= Right_Opnd
(P
)
2665 and then Nkind
(Left_Opnd
(P
)) = N_Op_Eq
;
2667 elsif K
= N_Or_Else
then
2668 exit when (N
= Right_Opnd
(P
)
2671 and then List_Containing
(N
) = Actions
(P
)))
2672 and then Nkind
(Left_Opnd
(P
)) = N_Op_Eq
;
2674 -- Similar test for the And/And then case, where the left operand
2675 -- is an inequality test.
2677 elsif K
= N_Op_And
then
2678 exit when N
= Right_Opnd
(P
)
2679 and then Nkind
(Left_Opnd
(P
)) = N_Op_Ne
;
2681 elsif K
= N_And_Then
then
2682 exit when (N
= Right_Opnd
(P
)
2685 and then List_Containing
(N
) = Actions
(P
)))
2686 and then Nkind
(Left_Opnd
(P
)) = N_Op_Ne
;
2692 -- If we fall through the loop, then we have a conditional with an
2693 -- appropriate test as its left operand. So test further.
2696 R
:= Right_Opnd
(L
);
2699 -- Left operand of test must match original variable
2701 if Nkind
(L
) not in N_Has_Entity
2702 or else Entity
(L
) /= Entity
(Nod
)
2707 -- Right operand of test must be key value (zero or null)
2710 when Access_Check
=>
2711 if not Known_Null
(R
) then
2715 when Division_Check
=>
2716 if not Compile_Time_Known_Value
(R
)
2717 or else Expr_Value
(R
) /= Uint_0
2723 raise Program_Error
;
2726 -- Here we have the optimizable case, warn if not short-circuited
2728 if K
= N_Op_And
or else K
= N_Op_Or
then
2730 when Access_Check
=>
2732 ("Constraint_Error may be raised (access check)?",
2734 when Division_Check
=>
2736 ("Constraint_Error may be raised (zero divide)?",
2740 raise Program_Error
;
2743 if K
= N_Op_And
then
2744 Error_Msg_N
-- CODEFIX
2745 ("use `AND THEN` instead of AND?", P
);
2747 Error_Msg_N
-- CODEFIX
2748 ("use `OR ELSE` instead of OR?", P
);
2751 -- If not short-circuited, we need the ckeck
2755 -- If short-circuited, we can omit the check
2762 -----------------------------------
2763 -- Check_Valid_Lvalue_Subscripts --
2764 -----------------------------------
2766 procedure Check_Valid_Lvalue_Subscripts
(Expr
: Node_Id
) is
2768 -- Skip this if range checks are suppressed
2770 if Range_Checks_Suppressed
(Etype
(Expr
)) then
2773 -- Only do this check for expressions that come from source. We assume
2774 -- that expander generated assignments explicitly include any necessary
2775 -- checks. Note that this is not just an optimization, it avoids
2776 -- infinite recursions!
2778 elsif not Comes_From_Source
(Expr
) then
2781 -- For a selected component, check the prefix
2783 elsif Nkind
(Expr
) = N_Selected_Component
then
2784 Check_Valid_Lvalue_Subscripts
(Prefix
(Expr
));
2787 -- Case of indexed component
2789 elsif Nkind
(Expr
) = N_Indexed_Component
then
2790 Apply_Subscript_Validity_Checks
(Expr
);
2792 -- Prefix may itself be or contain an indexed component, and these
2793 -- subscripts need checking as well.
2795 Check_Valid_Lvalue_Subscripts
(Prefix
(Expr
));
2797 end Check_Valid_Lvalue_Subscripts
;
2799 ----------------------------------
2800 -- Null_Exclusion_Static_Checks --
2801 ----------------------------------
2803 procedure Null_Exclusion_Static_Checks
(N
: Node_Id
) is
2804 Error_Node
: Node_Id
;
2806 Has_Null
: constant Boolean := Has_Null_Exclusion
(N
);
2807 K
: constant Node_Kind
:= Nkind
(N
);
2812 (K
= N_Component_Declaration
2813 or else K
= N_Discriminant_Specification
2814 or else K
= N_Function_Specification
2815 or else K
= N_Object_Declaration
2816 or else K
= N_Parameter_Specification
);
2818 if K
= N_Function_Specification
then
2819 Typ
:= Etype
(Defining_Entity
(N
));
2821 Typ
:= Etype
(Defining_Identifier
(N
));
2825 when N_Component_Declaration
=>
2826 if Present
(Access_Definition
(Component_Definition
(N
))) then
2827 Error_Node
:= Component_Definition
(N
);
2829 Error_Node
:= Subtype_Indication
(Component_Definition
(N
));
2832 when N_Discriminant_Specification
=>
2833 Error_Node
:= Discriminant_Type
(N
);
2835 when N_Function_Specification
=>
2836 Error_Node
:= Result_Definition
(N
);
2838 when N_Object_Declaration
=>
2839 Error_Node
:= Object_Definition
(N
);
2841 when N_Parameter_Specification
=>
2842 Error_Node
:= Parameter_Type
(N
);
2845 raise Program_Error
;
2850 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2851 -- applied to an access [sub]type.
2853 if not Is_Access_Type
(Typ
) then
2855 ("`NOT NULL` allowed only for an access type", Error_Node
);
2857 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2858 -- be applied to a [sub]type that does not exclude null already.
2860 elsif Can_Never_Be_Null
(Typ
)
2861 and then Comes_From_Source
(Typ
)
2864 ("`NOT NULL` not allowed (& already excludes null)",
2869 -- Check that null-excluding objects are always initialized, except for
2870 -- deferred constants, for which the expression will appear in the full
2873 if K
= N_Object_Declaration
2874 and then No
(Expression
(N
))
2875 and then not Constant_Present
(N
)
2876 and then not No_Initialization
(N
)
2878 -- Add an expression that assigns null. This node is needed by
2879 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2880 -- a Constraint_Error node.
2882 Set_Expression
(N
, Make_Null
(Sloc
(N
)));
2883 Set_Etype
(Expression
(N
), Etype
(Defining_Identifier
(N
)));
2885 Apply_Compile_Time_Constraint_Error
2886 (N
=> Expression
(N
),
2887 Msg
=> "(Ada 2005) null-excluding objects must be initialized?",
2888 Reason
=> CE_Null_Not_Allowed
);
2891 -- Check that a null-excluding component, formal or object is not being
2892 -- assigned a null value. Otherwise generate a warning message and
2893 -- replace Expression (N) by an N_Constraint_Error node.
2895 if K
/= N_Function_Specification
then
2896 Expr
:= Expression
(N
);
2898 if Present
(Expr
) and then Known_Null
(Expr
) then
2900 when N_Component_Declaration |
2901 N_Discriminant_Specification
=>
2902 Apply_Compile_Time_Constraint_Error
2904 Msg
=> "(Ada 2005) null not allowed " &
2905 "in null-excluding components?",
2906 Reason
=> CE_Null_Not_Allowed
);
2908 when N_Object_Declaration
=>
2909 Apply_Compile_Time_Constraint_Error
2911 Msg
=> "(Ada 2005) null not allowed " &
2912 "in null-excluding objects?",
2913 Reason
=> CE_Null_Not_Allowed
);
2915 when N_Parameter_Specification
=>
2916 Apply_Compile_Time_Constraint_Error
2918 Msg
=> "(Ada 2005) null not allowed " &
2919 "in null-excluding formals?",
2920 Reason
=> CE_Null_Not_Allowed
);
2927 end Null_Exclusion_Static_Checks
;
2929 ----------------------------------
2930 -- Conditional_Statements_Begin --
2931 ----------------------------------
2933 procedure Conditional_Statements_Begin
is
2935 Saved_Checks_TOS
:= Saved_Checks_TOS
+ 1;
2937 -- If stack overflows, kill all checks, that way we know to simply reset
2938 -- the number of saved checks to zero on return. This should never occur
2941 if Saved_Checks_TOS
> Saved_Checks_Stack
'Last then
2944 -- In the normal case, we just make a new stack entry saving the current
2945 -- number of saved checks for a later restore.
2948 Saved_Checks_Stack
(Saved_Checks_TOS
) := Num_Saved_Checks
;
2950 if Debug_Flag_CC
then
2951 w
("Conditional_Statements_Begin: Num_Saved_Checks = ",
2955 end Conditional_Statements_Begin
;
2957 --------------------------------
2958 -- Conditional_Statements_End --
2959 --------------------------------
2961 procedure Conditional_Statements_End
is
2963 pragma Assert
(Saved_Checks_TOS
> 0);
2965 -- If the saved checks stack overflowed, then we killed all checks, so
2966 -- setting the number of saved checks back to zero is correct. This
2967 -- should never occur in practice.
2969 if Saved_Checks_TOS
> Saved_Checks_Stack
'Last then
2970 Num_Saved_Checks
:= 0;
2972 -- In the normal case, restore the number of saved checks from the top
2976 Num_Saved_Checks
:= Saved_Checks_Stack
(Saved_Checks_TOS
);
2977 if Debug_Flag_CC
then
2978 w
("Conditional_Statements_End: Num_Saved_Checks = ",
2983 Saved_Checks_TOS
:= Saved_Checks_TOS
- 1;
2984 end Conditional_Statements_End
;
2986 ---------------------
2987 -- Determine_Range --
2988 ---------------------
2990 Cache_Size
: constant := 2 ** 10;
2991 type Cache_Index
is range 0 .. Cache_Size
- 1;
2992 -- Determine size of below cache (power of 2 is more efficient!)
2994 Determine_Range_Cache_N
: array (Cache_Index
) of Node_Id
;
2995 Determine_Range_Cache_V
: array (Cache_Index
) of Boolean;
2996 Determine_Range_Cache_Lo
: array (Cache_Index
) of Uint
;
2997 Determine_Range_Cache_Hi
: array (Cache_Index
) of Uint
;
2998 -- The above arrays are used to implement a small direct cache for
2999 -- Determine_Range calls. Because of the way Determine_Range recursively
3000 -- traces subexpressions, and because overflow checking calls the routine
3001 -- on the way up the tree, a quadratic behavior can otherwise be
3002 -- encountered in large expressions. The cache entry for node N is stored
3003 -- in the (N mod Cache_Size) entry, and can be validated by checking the
3004 -- actual node value stored there. The Range_Cache_V array records the
3005 -- setting of Assume_Valid for the cache entry.
3007 procedure Determine_Range
3012 Assume_Valid
: Boolean := False)
3014 Typ
: Entity_Id
:= Etype
(N
);
3015 -- Type to use, may get reset to base type for possibly invalid entity
3019 -- Lo and Hi bounds of left operand
3023 -- Lo and Hi bounds of right (or only) operand
3026 -- Temp variable used to hold a bound node
3029 -- High bound of base type of expression
3033 -- Refined values for low and high bounds, after tightening
3036 -- Used in lower level calls to indicate if call succeeded
3038 Cindex
: Cache_Index
;
3039 -- Used to search cache
3041 function OK_Operands
return Boolean;
3042 -- Used for binary operators. Determines the ranges of the left and
3043 -- right operands, and if they are both OK, returns True, and puts
3044 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
3050 function OK_Operands
return Boolean is
3053 (Left_Opnd
(N
), OK1
, Lo_Left
, Hi_Left
, Assume_Valid
);
3060 (Right_Opnd
(N
), OK1
, Lo_Right
, Hi_Right
, Assume_Valid
);
3064 -- Start of processing for Determine_Range
3067 -- Prevent junk warnings by initializing range variables
3074 -- If type is not defined, we can't determine its range
3078 -- We don't deal with anything except discrete types
3080 or else not Is_Discrete_Type
(Typ
)
3082 -- Ignore type for which an error has been posted, since range in
3083 -- this case may well be a bogosity deriving from the error. Also
3084 -- ignore if error posted on the reference node.
3086 or else Error_Posted
(N
) or else Error_Posted
(Typ
)
3092 -- For all other cases, we can determine the range
3096 -- If value is compile time known, then the possible range is the one
3097 -- value that we know this expression definitely has!
3099 if Compile_Time_Known_Value
(N
) then
3100 Lo
:= Expr_Value
(N
);
3105 -- Return if already in the cache
3107 Cindex
:= Cache_Index
(N
mod Cache_Size
);
3109 if Determine_Range_Cache_N
(Cindex
) = N
3111 Determine_Range_Cache_V
(Cindex
) = Assume_Valid
3113 Lo
:= Determine_Range_Cache_Lo
(Cindex
);
3114 Hi
:= Determine_Range_Cache_Hi
(Cindex
);
3118 -- Otherwise, start by finding the bounds of the type of the expression,
3119 -- the value cannot be outside this range (if it is, then we have an
3120 -- overflow situation, which is a separate check, we are talking here
3121 -- only about the expression value).
3123 -- First a check, never try to find the bounds of a generic type, since
3124 -- these bounds are always junk values, and it is only valid to look at
3125 -- the bounds in an instance.
3127 if Is_Generic_Type
(Typ
) then
3132 -- First step, change to use base type unless we know the value is valid
3134 if (Is_Entity_Name
(N
) and then Is_Known_Valid
(Entity
(N
)))
3135 or else Assume_No_Invalid_Values
3136 or else Assume_Valid
3140 Typ
:= Underlying_Type
(Base_Type
(Typ
));
3143 -- We use the actual bound unless it is dynamic, in which case use the
3144 -- corresponding base type bound if possible. If we can't get a bound
3145 -- then we figure we can't determine the range (a peculiar case, that
3146 -- perhaps cannot happen, but there is no point in bombing in this
3147 -- optimization circuit.
3149 -- First the low bound
3151 Bound
:= Type_Low_Bound
(Typ
);
3153 if Compile_Time_Known_Value
(Bound
) then
3154 Lo
:= Expr_Value
(Bound
);
3156 elsif Compile_Time_Known_Value
(Type_Low_Bound
(Base_Type
(Typ
))) then
3157 Lo
:= Expr_Value
(Type_Low_Bound
(Base_Type
(Typ
)));
3164 -- Now the high bound
3166 Bound
:= Type_High_Bound
(Typ
);
3168 -- We need the high bound of the base type later on, and this should
3169 -- always be compile time known. Again, it is not clear that this
3170 -- can ever be false, but no point in bombing.
3172 if Compile_Time_Known_Value
(Type_High_Bound
(Base_Type
(Typ
))) then
3173 Hbound
:= Expr_Value
(Type_High_Bound
(Base_Type
(Typ
)));
3181 -- If we have a static subtype, then that may have a tighter bound so
3182 -- use the upper bound of the subtype instead in this case.
3184 if Compile_Time_Known_Value
(Bound
) then
3185 Hi
:= Expr_Value
(Bound
);
3188 -- We may be able to refine this value in certain situations. If any
3189 -- refinement is possible, then Lor and Hir are set to possibly tighter
3190 -- bounds, and OK1 is set to True.
3194 -- For unary plus, result is limited by range of operand
3198 (Right_Opnd
(N
), OK1
, Lor
, Hir
, Assume_Valid
);
3200 -- For unary minus, determine range of operand, and negate it
3204 (Right_Opnd
(N
), OK1
, Lo_Right
, Hi_Right
, Assume_Valid
);
3211 -- For binary addition, get range of each operand and do the
3212 -- addition to get the result range.
3216 Lor
:= Lo_Left
+ Lo_Right
;
3217 Hir
:= Hi_Left
+ Hi_Right
;
3220 -- Division is tricky. The only case we consider is where the right
3221 -- operand is a positive constant, and in this case we simply divide
3222 -- the bounds of the left operand
3226 if Lo_Right
= Hi_Right
3227 and then Lo_Right
> 0
3229 Lor
:= Lo_Left
/ Lo_Right
;
3230 Hir
:= Hi_Left
/ Lo_Right
;
3237 -- For binary subtraction, get range of each operand and do the worst
3238 -- case subtraction to get the result range.
3240 when N_Op_Subtract
=>
3242 Lor
:= Lo_Left
- Hi_Right
;
3243 Hir
:= Hi_Left
- Lo_Right
;
3246 -- For MOD, if right operand is a positive constant, then result must
3247 -- be in the allowable range of mod results.
3251 if Lo_Right
= Hi_Right
3252 and then Lo_Right
/= 0
3254 if Lo_Right
> 0 then
3256 Hir
:= Lo_Right
- 1;
3258 else -- Lo_Right < 0
3259 Lor
:= Lo_Right
+ 1;
3268 -- For REM, if right operand is a positive constant, then result must
3269 -- be in the allowable range of mod results.
3273 if Lo_Right
= Hi_Right
3274 and then Lo_Right
/= 0
3277 Dval
: constant Uint
:= (abs Lo_Right
) - 1;
3280 -- The sign of the result depends on the sign of the
3281 -- dividend (but not on the sign of the divisor, hence
3282 -- the abs operation above).
3302 -- Attribute reference cases
3304 when N_Attribute_Reference
=>
3305 case Attribute_Name
(N
) is
3307 -- For Pos/Val attributes, we can refine the range using the
3308 -- possible range of values of the attribute expression.
3310 when Name_Pos | Name_Val
=>
3312 (First
(Expressions
(N
)), OK1
, Lor
, Hir
, Assume_Valid
);
3314 -- For Length attribute, use the bounds of the corresponding
3315 -- index type to refine the range.
3319 Atyp
: Entity_Id
:= Etype
(Prefix
(N
));
3327 if Is_Access_Type
(Atyp
) then
3328 Atyp
:= Designated_Type
(Atyp
);
3331 -- For string literal, we know exact value
3333 if Ekind
(Atyp
) = E_String_Literal_Subtype
then
3335 Lo
:= String_Literal_Length
(Atyp
);
3336 Hi
:= String_Literal_Length
(Atyp
);
3340 -- Otherwise check for expression given
3342 if No
(Expressions
(N
)) then
3346 UI_To_Int
(Expr_Value
(First
(Expressions
(N
))));
3349 Indx
:= First_Index
(Atyp
);
3350 for J
in 2 .. Inum
loop
3351 Indx
:= Next_Index
(Indx
);
3354 -- If the index type is a formal type or derived from
3355 -- one, the bounds are not static.
3357 if Is_Generic_Type
(Root_Type
(Etype
(Indx
))) then
3363 (Type_Low_Bound
(Etype
(Indx
)), OK1
, LL
, LU
,
3368 (Type_High_Bound
(Etype
(Indx
)), OK1
, UL
, UU
,
3373 -- The maximum value for Length is the biggest
3374 -- possible gap between the values of the bounds.
3375 -- But of course, this value cannot be negative.
3377 Hir
:= UI_Max
(Uint_0
, UU
- LL
+ 1);
3379 -- For constrained arrays, the minimum value for
3380 -- Length is taken from the actual value of the
3381 -- bounds, since the index will be exactly of this
3384 if Is_Constrained
(Atyp
) then
3385 Lor
:= UI_Max
(Uint_0
, UL
- LU
+ 1);
3387 -- For an unconstrained array, the minimum value
3388 -- for length is always zero.
3397 -- No special handling for other attributes
3398 -- Probably more opportunities exist here???
3405 -- For type conversion from one discrete type to another, we can
3406 -- refine the range using the converted value.
3408 when N_Type_Conversion
=>
3409 Determine_Range
(Expression
(N
), OK1
, Lor
, Hir
, Assume_Valid
);
3411 -- Nothing special to do for all other expression kinds
3419 -- At this stage, if OK1 is true, then we know that the actual result of
3420 -- the computed expression is in the range Lor .. Hir. We can use this
3421 -- to restrict the possible range of results.
3425 -- If the refined value of the low bound is greater than the type
3426 -- high bound, then reset it to the more restrictive value. However,
3427 -- we do NOT do this for the case of a modular type where the
3428 -- possible upper bound on the value is above the base type high
3429 -- bound, because that means the result could wrap.
3432 and then not (Is_Modular_Integer_Type
(Typ
) and then Hir
> Hbound
)
3437 -- Similarly, if the refined value of the high bound is less than the
3438 -- value so far, then reset it to the more restrictive value. Again,
3439 -- we do not do this if the refined low bound is negative for a
3440 -- modular type, since this would wrap.
3443 and then not (Is_Modular_Integer_Type
(Typ
) and then Lor
< Uint_0
)
3449 -- Set cache entry for future call and we are all done
3451 Determine_Range_Cache_N
(Cindex
) := N
;
3452 Determine_Range_Cache_V
(Cindex
) := Assume_Valid
;
3453 Determine_Range_Cache_Lo
(Cindex
) := Lo
;
3454 Determine_Range_Cache_Hi
(Cindex
) := Hi
;
3457 -- If any exception occurs, it means that we have some bug in the compiler,
3458 -- possibly triggered by a previous error, or by some unforeseen peculiar
3459 -- occurrence. However, this is only an optimization attempt, so there is
3460 -- really no point in crashing the compiler. Instead we just decide, too
3461 -- bad, we can't figure out a range in this case after all.
3466 -- Debug flag K disables this behavior (useful for debugging)
3468 if Debug_Flag_K
then
3476 end Determine_Range
;
3478 ------------------------------------
3479 -- Discriminant_Checks_Suppressed --
3480 ------------------------------------
3482 function Discriminant_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
3485 if Is_Unchecked_Union
(E
) then
3487 elsif Checks_May_Be_Suppressed
(E
) then
3488 return Is_Check_Suppressed
(E
, Discriminant_Check
);
3492 return Scope_Suppress
(Discriminant_Check
);
3493 end Discriminant_Checks_Suppressed
;
3495 --------------------------------
3496 -- Division_Checks_Suppressed --
3497 --------------------------------
3499 function Division_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
3501 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
3502 return Is_Check_Suppressed
(E
, Division_Check
);
3504 return Scope_Suppress
(Division_Check
);
3506 end Division_Checks_Suppressed
;
3508 -----------------------------------
3509 -- Elaboration_Checks_Suppressed --
3510 -----------------------------------
3512 function Elaboration_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
3514 -- The complication in this routine is that if we are in the dynamic
3515 -- model of elaboration, we also check All_Checks, since All_Checks
3516 -- does not set Elaboration_Check explicitly.
3519 if Kill_Elaboration_Checks
(E
) then
3522 elsif Checks_May_Be_Suppressed
(E
) then
3523 if Is_Check_Suppressed
(E
, Elaboration_Check
) then
3525 elsif Dynamic_Elaboration_Checks
then
3526 return Is_Check_Suppressed
(E
, All_Checks
);
3533 if Scope_Suppress
(Elaboration_Check
) then
3535 elsif Dynamic_Elaboration_Checks
then
3536 return Scope_Suppress
(All_Checks
);
3540 end Elaboration_Checks_Suppressed
;
3542 ---------------------------
3543 -- Enable_Overflow_Check --
3544 ---------------------------
3546 procedure Enable_Overflow_Check
(N
: Node_Id
) is
3547 Typ
: constant Entity_Id
:= Base_Type
(Etype
(N
));
3556 if Debug_Flag_CC
then
3557 w
("Enable_Overflow_Check for node ", Int
(N
));
3558 Write_Str
(" Source location = ");
3563 -- No check if overflow checks suppressed for type of node
3565 if Present
(Etype
(N
))
3566 and then Overflow_Checks_Suppressed
(Etype
(N
))
3570 -- Nothing to do for unsigned integer types, which do not overflow
3572 elsif Is_Modular_Integer_Type
(Typ
) then
3575 -- Nothing to do if the range of the result is known OK. We skip this
3576 -- for conversions, since the caller already did the check, and in any
3577 -- case the condition for deleting the check for a type conversion is
3580 elsif Nkind
(N
) /= N_Type_Conversion
then
3581 Determine_Range
(N
, OK
, Lo
, Hi
, Assume_Valid
=> True);
3583 -- Note in the test below that we assume that the range is not OK
3584 -- if a bound of the range is equal to that of the type. That's not
3585 -- quite accurate but we do this for the following reasons:
3587 -- a) The way that Determine_Range works, it will typically report
3588 -- the bounds of the value as being equal to the bounds of the
3589 -- type, because it either can't tell anything more precise, or
3590 -- does not think it is worth the effort to be more precise.
3592 -- b) It is very unusual to have a situation in which this would
3593 -- generate an unnecessary overflow check (an example would be
3594 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3595 -- literal value one is added).
3597 -- c) The alternative is a lot of special casing in this routine
3598 -- which would partially duplicate Determine_Range processing.
3601 and then Lo
> Expr_Value
(Type_Low_Bound
(Typ
))
3602 and then Hi
< Expr_Value
(Type_High_Bound
(Typ
))
3604 if Debug_Flag_CC
then
3605 w
("No overflow check required");
3612 -- If not in optimizing mode, set flag and we are done. We are also done
3613 -- (and just set the flag) if the type is not a discrete type, since it
3614 -- is not worth the effort to eliminate checks for other than discrete
3615 -- types. In addition, we take this same path if we have stored the
3616 -- maximum number of checks possible already (a very unlikely situation,
3617 -- but we do not want to blow up!)
3619 if Optimization_Level
= 0
3620 or else not Is_Discrete_Type
(Etype
(N
))
3621 or else Num_Saved_Checks
= Saved_Checks
'Last
3623 Activate_Overflow_Check
(N
);
3625 if Debug_Flag_CC
then
3626 w
("Optimization off");
3632 -- Otherwise evaluate and check the expression
3637 Target_Type
=> Empty
,
3643 if Debug_Flag_CC
then
3644 w
("Called Find_Check");
3648 w
(" Check_Num = ", Chk
);
3649 w
(" Ent = ", Int
(Ent
));
3650 Write_Str
(" Ofs = ");
3655 -- If check is not of form to optimize, then set flag and we are done
3658 Activate_Overflow_Check
(N
);
3662 -- If check is already performed, then return without setting flag
3665 if Debug_Flag_CC
then
3666 w
("Check suppressed!");
3672 -- Here we will make a new entry for the new check
3674 Activate_Overflow_Check
(N
);
3675 Num_Saved_Checks
:= Num_Saved_Checks
+ 1;
3676 Saved_Checks
(Num_Saved_Checks
) :=
3681 Target_Type
=> Empty
);
3683 if Debug_Flag_CC
then
3684 w
("Make new entry, check number = ", Num_Saved_Checks
);
3685 w
(" Entity = ", Int
(Ent
));
3686 Write_Str
(" Offset = ");
3688 w
(" Check_Type = O");
3689 w
(" Target_Type = Empty");
3692 -- If we get an exception, then something went wrong, probably because of
3693 -- an error in the structure of the tree due to an incorrect program. Or it
3694 -- may be a bug in the optimization circuit. In either case the safest
3695 -- thing is simply to set the check flag unconditionally.
3699 Activate_Overflow_Check
(N
);
3701 if Debug_Flag_CC
then
3702 w
(" exception occurred, overflow flag set");
3706 end Enable_Overflow_Check
;
3708 ------------------------
3709 -- Enable_Range_Check --
3710 ------------------------
3712 procedure Enable_Range_Check
(N
: Node_Id
) is
3721 -- Return if unchecked type conversion with range check killed. In this
3722 -- case we never set the flag (that's what Kill_Range_Check is about!)
3724 if Nkind
(N
) = N_Unchecked_Type_Conversion
3725 and then Kill_Range_Check
(N
)
3730 -- Check for various cases where we should suppress the range check
3732 -- No check if range checks suppressed for type of node
3734 if Present
(Etype
(N
))
3735 and then Range_Checks_Suppressed
(Etype
(N
))
3739 -- No check if node is an entity name, and range checks are suppressed
3740 -- for this entity, or for the type of this entity.
3742 elsif Is_Entity_Name
(N
)
3743 and then (Range_Checks_Suppressed
(Entity
(N
))
3744 or else Range_Checks_Suppressed
(Etype
(Entity
(N
))))
3748 -- No checks if index of array, and index checks are suppressed for
3749 -- the array object or the type of the array.
3751 elsif Nkind
(Parent
(N
)) = N_Indexed_Component
then
3753 Pref
: constant Node_Id
:= Prefix
(Parent
(N
));
3755 if Is_Entity_Name
(Pref
)
3756 and then Index_Checks_Suppressed
(Entity
(Pref
))
3759 elsif Index_Checks_Suppressed
(Etype
(Pref
)) then
3765 -- Debug trace output
3767 if Debug_Flag_CC
then
3768 w
("Enable_Range_Check for node ", Int
(N
));
3769 Write_Str
(" Source location = ");
3774 -- If not in optimizing mode, set flag and we are done. We are also done
3775 -- (and just set the flag) if the type is not a discrete type, since it
3776 -- is not worth the effort to eliminate checks for other than discrete
3777 -- types. In addition, we take this same path if we have stored the
3778 -- maximum number of checks possible already (a very unlikely situation,
3779 -- but we do not want to blow up!)
3781 if Optimization_Level
= 0
3782 or else No
(Etype
(N
))
3783 or else not Is_Discrete_Type
(Etype
(N
))
3784 or else Num_Saved_Checks
= Saved_Checks
'Last
3786 Activate_Range_Check
(N
);
3788 if Debug_Flag_CC
then
3789 w
("Optimization off");
3795 -- Otherwise find out the target type
3799 -- For assignment, use left side subtype
3801 if Nkind
(P
) = N_Assignment_Statement
3802 and then Expression
(P
) = N
3804 Ttyp
:= Etype
(Name
(P
));
3806 -- For indexed component, use subscript subtype
3808 elsif Nkind
(P
) = N_Indexed_Component
then
3815 Atyp
:= Etype
(Prefix
(P
));
3817 if Is_Access_Type
(Atyp
) then
3818 Atyp
:= Designated_Type
(Atyp
);
3820 -- If the prefix is an access to an unconstrained array,
3821 -- perform check unconditionally: it depends on the bounds of
3822 -- an object and we cannot currently recognize whether the test
3823 -- may be redundant.
3825 if not Is_Constrained
(Atyp
) then
3826 Activate_Range_Check
(N
);
3830 -- Ditto if the prefix is an explicit dereference whose designated
3831 -- type is unconstrained.
3833 elsif Nkind
(Prefix
(P
)) = N_Explicit_Dereference
3834 and then not Is_Constrained
(Atyp
)
3836 Activate_Range_Check
(N
);
3840 Indx
:= First_Index
(Atyp
);
3841 Subs
:= First
(Expressions
(P
));
3844 Ttyp
:= Etype
(Indx
);
3853 -- For now, ignore all other cases, they are not so interesting
3856 if Debug_Flag_CC
then
3857 w
(" target type not found, flag set");
3860 Activate_Range_Check
(N
);
3864 -- Evaluate and check the expression
3869 Target_Type
=> Ttyp
,
3875 if Debug_Flag_CC
then
3876 w
("Called Find_Check");
3877 w
("Target_Typ = ", Int
(Ttyp
));
3881 w
(" Check_Num = ", Chk
);
3882 w
(" Ent = ", Int
(Ent
));
3883 Write_Str
(" Ofs = ");
3888 -- If check is not of form to optimize, then set flag and we are done
3891 if Debug_Flag_CC
then
3892 w
(" expression not of optimizable type, flag set");
3895 Activate_Range_Check
(N
);
3899 -- If check is already performed, then return without setting flag
3902 if Debug_Flag_CC
then
3903 w
("Check suppressed!");
3909 -- Here we will make a new entry for the new check
3911 Activate_Range_Check
(N
);
3912 Num_Saved_Checks
:= Num_Saved_Checks
+ 1;
3913 Saved_Checks
(Num_Saved_Checks
) :=
3918 Target_Type
=> Ttyp
);
3920 if Debug_Flag_CC
then
3921 w
("Make new entry, check number = ", Num_Saved_Checks
);
3922 w
(" Entity = ", Int
(Ent
));
3923 Write_Str
(" Offset = ");
3925 w
(" Check_Type = R");
3926 w
(" Target_Type = ", Int
(Ttyp
));
3927 pg
(Union_Id
(Ttyp
));
3930 -- If we get an exception, then something went wrong, probably because of
3931 -- an error in the structure of the tree due to an incorrect program. Or
3932 -- it may be a bug in the optimization circuit. In either case the safest
3933 -- thing is simply to set the check flag unconditionally.
3937 Activate_Range_Check
(N
);
3939 if Debug_Flag_CC
then
3940 w
(" exception occurred, range flag set");
3944 end Enable_Range_Check
;
3950 procedure Ensure_Valid
(Expr
: Node_Id
; Holes_OK
: Boolean := False) is
3951 Typ
: constant Entity_Id
:= Etype
(Expr
);
3954 -- Ignore call if we are not doing any validity checking
3956 if not Validity_Checks_On
then
3959 -- Ignore call if range or validity checks suppressed on entity or type
3961 elsif Range_Or_Validity_Checks_Suppressed
(Expr
) then
3964 -- No check required if expression is from the expander, we assume the
3965 -- expander will generate whatever checks are needed. Note that this is
3966 -- not just an optimization, it avoids infinite recursions!
3968 -- Unchecked conversions must be checked, unless they are initialized
3969 -- scalar values, as in a component assignment in an init proc.
3971 -- In addition, we force a check if Force_Validity_Checks is set
3973 elsif not Comes_From_Source
(Expr
)
3974 and then not Force_Validity_Checks
3975 and then (Nkind
(Expr
) /= N_Unchecked_Type_Conversion
3976 or else Kill_Range_Check
(Expr
))
3980 -- No check required if expression is known to have valid value
3982 elsif Expr_Known_Valid
(Expr
) then
3985 -- Ignore case of enumeration with holes where the flag is set not to
3986 -- worry about holes, since no special validity check is needed
3988 elsif Is_Enumeration_Type
(Typ
)
3989 and then Has_Non_Standard_Rep
(Typ
)
3994 -- No check required on the left-hand side of an assignment
3996 elsif Nkind
(Parent
(Expr
)) = N_Assignment_Statement
3997 and then Expr
= Name
(Parent
(Expr
))
4001 -- No check on a univeral real constant. The context will eventually
4002 -- convert it to a machine number for some target type, or report an
4005 elsif Nkind
(Expr
) = N_Real_Literal
4006 and then Etype
(Expr
) = Universal_Real
4010 -- If the expression denotes a component of a packed boolean arrray,
4011 -- no possible check applies. We ignore the old ACATS chestnuts that
4012 -- involve Boolean range True..True.
4014 -- Note: validity checks are generated for expressions that yield a
4015 -- scalar type, when it is possible to create a value that is outside of
4016 -- the type. If this is a one-bit boolean no such value exists. This is
4017 -- an optimization, and it also prevents compiler blowing up during the
4018 -- elaboration of improperly expanded packed array references.
4020 elsif Nkind
(Expr
) = N_Indexed_Component
4021 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Expr
)))
4022 and then Root_Type
(Etype
(Expr
)) = Standard_Boolean
4026 -- An annoying special case. If this is an out parameter of a scalar
4027 -- type, then the value is not going to be accessed, therefore it is
4028 -- inappropriate to do any validity check at the call site.
4031 -- Only need to worry about scalar types
4033 if Is_Scalar_Type
(Typ
) then
4043 -- Find actual argument (which may be a parameter association)
4044 -- and the parent of the actual argument (the call statement)
4049 if Nkind
(P
) = N_Parameter_Association
then
4054 -- Only need to worry if we are argument of a procedure call
4055 -- since functions don't have out parameters. If this is an
4056 -- indirect or dispatching call, get signature from the
4059 if Nkind
(P
) = N_Procedure_Call_Statement
then
4060 L
:= Parameter_Associations
(P
);
4062 if Is_Entity_Name
(Name
(P
)) then
4063 E
:= Entity
(Name
(P
));
4065 pragma Assert
(Nkind
(Name
(P
)) = N_Explicit_Dereference
);
4066 E
:= Etype
(Name
(P
));
4069 -- Only need to worry if there are indeed actuals, and if
4070 -- this could be a procedure call, otherwise we cannot get a
4071 -- match (either we are not an argument, or the mode of the
4072 -- formal is not OUT). This test also filters out the
4075 if Is_Non_Empty_List
(L
)
4076 and then Is_Subprogram
(E
)
4078 -- This is the loop through parameters, looking for an
4079 -- OUT parameter for which we are the argument.
4081 F
:= First_Formal
(E
);
4083 while Present
(F
) loop
4084 if Ekind
(F
) = E_Out_Parameter
and then A
= N
then
4097 -- If we fall through, a validity check is required
4099 Insert_Valid_Check
(Expr
);
4101 if Is_Entity_Name
(Expr
)
4102 and then Safe_To_Capture_Value
(Expr
, Entity
(Expr
))
4104 Set_Is_Known_Valid
(Entity
(Expr
));
4108 ----------------------
4109 -- Expr_Known_Valid --
4110 ----------------------
4112 function Expr_Known_Valid
(Expr
: Node_Id
) return Boolean is
4113 Typ
: constant Entity_Id
:= Etype
(Expr
);
4116 -- Non-scalar types are always considered valid, since they never give
4117 -- rise to the issues of erroneous or bounded error behavior that are
4118 -- the concern. In formal reference manual terms the notion of validity
4119 -- only applies to scalar types. Note that even when packed arrays are
4120 -- represented using modular types, they are still arrays semantically,
4121 -- so they are also always valid (in particular, the unused bits can be
4122 -- random rubbish without affecting the validity of the array value).
4124 if not Is_Scalar_Type
(Typ
) or else Is_Packed_Array_Type
(Typ
) then
4127 -- If no validity checking, then everything is considered valid
4129 elsif not Validity_Checks_On
then
4132 -- Floating-point types are considered valid unless floating-point
4133 -- validity checks have been specifically turned on.
4135 elsif Is_Floating_Point_Type
(Typ
)
4136 and then not Validity_Check_Floating_Point
4140 -- If the expression is the value of an object that is known to be
4141 -- valid, then clearly the expression value itself is valid.
4143 elsif Is_Entity_Name
(Expr
)
4144 and then Is_Known_Valid
(Entity
(Expr
))
4148 -- References to discriminants are always considered valid. The value
4149 -- of a discriminant gets checked when the object is built. Within the
4150 -- record, we consider it valid, and it is important to do so, since
4151 -- otherwise we can try to generate bogus validity checks which
4152 -- reference discriminants out of scope. Discriminants of concurrent
4153 -- types are excluded for the same reason.
4155 elsif Is_Entity_Name
(Expr
)
4156 and then Denotes_Discriminant
(Expr
, Check_Concurrent
=> True)
4160 -- If the type is one for which all values are known valid, then we are
4161 -- sure that the value is valid except in the slightly odd case where
4162 -- the expression is a reference to a variable whose size has been
4163 -- explicitly set to a value greater than the object size.
4165 elsif Is_Known_Valid
(Typ
) then
4166 if Is_Entity_Name
(Expr
)
4167 and then Ekind
(Entity
(Expr
)) = E_Variable
4168 and then Esize
(Entity
(Expr
)) > Esize
(Typ
)
4175 -- Integer and character literals always have valid values, where
4176 -- appropriate these will be range checked in any case.
4178 elsif Nkind
(Expr
) = N_Integer_Literal
4180 Nkind
(Expr
) = N_Character_Literal
4184 -- If we have a type conversion or a qualification of a known valid
4185 -- value, then the result will always be valid.
4187 elsif Nkind
(Expr
) = N_Type_Conversion
4189 Nkind
(Expr
) = N_Qualified_Expression
4191 return Expr_Known_Valid
(Expression
(Expr
));
4193 -- The result of any operator is always considered valid, since we
4194 -- assume the necessary checks are done by the operator. For operators
4195 -- on floating-point operations, we must also check when the operation
4196 -- is the right-hand side of an assignment, or is an actual in a call.
4198 elsif Nkind
(Expr
) in N_Op
then
4199 if Is_Floating_Point_Type
(Typ
)
4200 and then Validity_Check_Floating_Point
4202 (Nkind
(Parent
(Expr
)) = N_Assignment_Statement
4203 or else Nkind
(Parent
(Expr
)) = N_Function_Call
4204 or else Nkind
(Parent
(Expr
)) = N_Parameter_Association
)
4211 -- The result of a membership test is always valid, since it is true or
4212 -- false, there are no other possibilities.
4214 elsif Nkind
(Expr
) in N_Membership_Test
then
4217 -- For all other cases, we do not know the expression is valid
4222 end Expr_Known_Valid
;
4228 procedure Find_Check
4230 Check_Type
: Character;
4231 Target_Type
: Entity_Id
;
4232 Entry_OK
: out Boolean;
4233 Check_Num
: out Nat
;
4234 Ent
: out Entity_Id
;
4237 function Within_Range_Of
4238 (Target_Type
: Entity_Id
;
4239 Check_Type
: Entity_Id
) return Boolean;
4240 -- Given a requirement for checking a range against Target_Type, and
4241 -- and a range Check_Type against which a check has already been made,
4242 -- determines if the check against check type is sufficient to ensure
4243 -- that no check against Target_Type is required.
4245 ---------------------
4246 -- Within_Range_Of --
4247 ---------------------
4249 function Within_Range_Of
4250 (Target_Type
: Entity_Id
;
4251 Check_Type
: Entity_Id
) return Boolean
4254 if Target_Type
= Check_Type
then
4259 Tlo
: constant Node_Id
:= Type_Low_Bound
(Target_Type
);
4260 Thi
: constant Node_Id
:= Type_High_Bound
(Target_Type
);
4261 Clo
: constant Node_Id
:= Type_Low_Bound
(Check_Type
);
4262 Chi
: constant Node_Id
:= Type_High_Bound
(Check_Type
);
4266 or else (Compile_Time_Known_Value
(Tlo
)
4268 Compile_Time_Known_Value
(Clo
)
4270 Expr_Value
(Clo
) >= Expr_Value
(Tlo
)))
4273 or else (Compile_Time_Known_Value
(Thi
)
4275 Compile_Time_Known_Value
(Chi
)
4277 Expr_Value
(Chi
) <= Expr_Value
(Clo
)))
4285 end Within_Range_Of
;
4287 -- Start of processing for Find_Check
4290 -- Establish default, in case no entry is found
4294 -- Case of expression is simple entity reference
4296 if Is_Entity_Name
(Expr
) then
4297 Ent
:= Entity
(Expr
);
4300 -- Case of expression is entity + known constant
4302 elsif Nkind
(Expr
) = N_Op_Add
4303 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
4304 and then Is_Entity_Name
(Left_Opnd
(Expr
))
4306 Ent
:= Entity
(Left_Opnd
(Expr
));
4307 Ofs
:= Expr_Value
(Right_Opnd
(Expr
));
4309 -- Case of expression is entity - known constant
4311 elsif Nkind
(Expr
) = N_Op_Subtract
4312 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
4313 and then Is_Entity_Name
(Left_Opnd
(Expr
))
4315 Ent
:= Entity
(Left_Opnd
(Expr
));
4316 Ofs
:= UI_Negate
(Expr_Value
(Right_Opnd
(Expr
)));
4318 -- Any other expression is not of the right form
4327 -- Come here with expression of appropriate form, check if entity is an
4328 -- appropriate one for our purposes.
4330 if (Ekind
(Ent
) = E_Variable
4331 or else Is_Constant_Object
(Ent
))
4332 and then not Is_Library_Level_Entity
(Ent
)
4340 -- See if there is matching check already
4342 for J
in reverse 1 .. Num_Saved_Checks
loop
4344 SC
: Saved_Check
renames Saved_Checks
(J
);
4347 if SC
.Killed
= False
4348 and then SC
.Entity
= Ent
4349 and then SC
.Offset
= Ofs
4350 and then SC
.Check_Type
= Check_Type
4351 and then Within_Range_Of
(Target_Type
, SC
.Target_Type
)
4359 -- If we fall through entry was not found
4364 ---------------------------------
4365 -- Generate_Discriminant_Check --
4366 ---------------------------------
4368 -- Note: the code for this procedure is derived from the
4369 -- Emit_Discriminant_Check Routine in trans.c.
4371 procedure Generate_Discriminant_Check
(N
: Node_Id
) is
4372 Loc
: constant Source_Ptr
:= Sloc
(N
);
4373 Pref
: constant Node_Id
:= Prefix
(N
);
4374 Sel
: constant Node_Id
:= Selector_Name
(N
);
4376 Orig_Comp
: constant Entity_Id
:=
4377 Original_Record_Component
(Entity
(Sel
));
4378 -- The original component to be checked
4380 Discr_Fct
: constant Entity_Id
:=
4381 Discriminant_Checking_Func
(Orig_Comp
);
4382 -- The discriminant checking function
4385 -- One discriminant to be checked in the type
4387 Real_Discr
: Entity_Id
;
4388 -- Actual discriminant in the call
4390 Pref_Type
: Entity_Id
;
4391 -- Type of relevant prefix (ignoring private/access stuff)
4394 -- List of arguments for function call
4397 -- Keep track of the formal corresponding to the actual we build for
4398 -- each discriminant, in order to be able to perform the necessary type
4402 -- Selected component reference for checking function argument
4405 Pref_Type
:= Etype
(Pref
);
4407 -- Force evaluation of the prefix, so that it does not get evaluated
4408 -- twice (once for the check, once for the actual reference). Such a
4409 -- double evaluation is always a potential source of inefficiency,
4410 -- and is functionally incorrect in the volatile case, or when the
4411 -- prefix may have side-effects. An entity or a component of an
4412 -- entity requires no evaluation.
4414 if Is_Entity_Name
(Pref
) then
4415 if Treat_As_Volatile
(Entity
(Pref
)) then
4416 Force_Evaluation
(Pref
, Name_Req
=> True);
4419 elsif Treat_As_Volatile
(Etype
(Pref
)) then
4420 Force_Evaluation
(Pref
, Name_Req
=> True);
4422 elsif Nkind
(Pref
) = N_Selected_Component
4423 and then Is_Entity_Name
(Prefix
(Pref
))
4428 Force_Evaluation
(Pref
, Name_Req
=> True);
4431 -- For a tagged type, use the scope of the original component to
4432 -- obtain the type, because ???
4434 if Is_Tagged_Type
(Scope
(Orig_Comp
)) then
4435 Pref_Type
:= Scope
(Orig_Comp
);
4437 -- For an untagged derived type, use the discriminants of the parent
4438 -- which have been renamed in the derivation, possibly by a one-to-many
4439 -- discriminant constraint. For non-tagged type, initially get the Etype
4443 if Is_Derived_Type
(Pref_Type
)
4444 and then Number_Discriminants
(Pref_Type
) /=
4445 Number_Discriminants
(Etype
(Base_Type
(Pref_Type
)))
4447 Pref_Type
:= Etype
(Base_Type
(Pref_Type
));
4451 -- We definitely should have a checking function, This routine should
4452 -- not be called if no discriminant checking function is present.
4454 pragma Assert
(Present
(Discr_Fct
));
4456 -- Create the list of the actual parameters for the call. This list
4457 -- is the list of the discriminant fields of the record expression to
4458 -- be discriminant checked.
4461 Formal
:= First_Formal
(Discr_Fct
);
4462 Discr
:= First_Discriminant
(Pref_Type
);
4463 while Present
(Discr
) loop
4465 -- If we have a corresponding discriminant field, and a parent
4466 -- subtype is present, then we want to use the corresponding
4467 -- discriminant since this is the one with the useful value.
4469 if Present
(Corresponding_Discriminant
(Discr
))
4470 and then Ekind
(Pref_Type
) = E_Record_Type
4471 and then Present
(Parent_Subtype
(Pref_Type
))
4473 Real_Discr
:= Corresponding_Discriminant
(Discr
);
4475 Real_Discr
:= Discr
;
4478 -- Construct the reference to the discriminant
4481 Make_Selected_Component
(Loc
,
4483 Unchecked_Convert_To
(Pref_Type
,
4484 Duplicate_Subexpr
(Pref
)),
4485 Selector_Name
=> New_Occurrence_Of
(Real_Discr
, Loc
));
4487 -- Manually analyze and resolve this selected component. We really
4488 -- want it just as it appears above, and do not want the expander
4489 -- playing discriminal games etc with this reference. Then we append
4490 -- the argument to the list we are gathering.
4492 Set_Etype
(Scomp
, Etype
(Real_Discr
));
4493 Set_Analyzed
(Scomp
, True);
4494 Append_To
(Args
, Convert_To
(Etype
(Formal
), Scomp
));
4496 Next_Formal_With_Extras
(Formal
);
4497 Next_Discriminant
(Discr
);
4500 -- Now build and insert the call
4503 Make_Raise_Constraint_Error
(Loc
,
4505 Make_Function_Call
(Loc
,
4506 Name
=> New_Occurrence_Of
(Discr_Fct
, Loc
),
4507 Parameter_Associations
=> Args
),
4508 Reason
=> CE_Discriminant_Check_Failed
));
4509 end Generate_Discriminant_Check
;
4511 ---------------------------
4512 -- Generate_Index_Checks --
4513 ---------------------------
4515 procedure Generate_Index_Checks
(N
: Node_Id
) is
4516 Loc
: constant Source_Ptr
:= Sloc
(N
);
4517 A
: constant Node_Id
:= Prefix
(N
);
4523 -- Ignore call if index checks suppressed for array object or type
4525 if (Is_Entity_Name
(A
) and then Index_Checks_Suppressed
(Entity
(A
)))
4526 or else Index_Checks_Suppressed
(Etype
(A
))
4531 -- Generate the checks
4533 Sub
:= First
(Expressions
(N
));
4535 while Present
(Sub
) loop
4536 if Do_Range_Check
(Sub
) then
4537 Set_Do_Range_Check
(Sub
, False);
4539 -- Force evaluation except for the case of a simple name of a
4540 -- non-volatile entity.
4542 if not Is_Entity_Name
(Sub
)
4543 or else Treat_As_Volatile
(Entity
(Sub
))
4545 Force_Evaluation
(Sub
);
4548 -- Generate a raise of constraint error with the appropriate
4549 -- reason and a condition of the form:
4551 -- Base_Type(Sub) not in array'range (subscript)
4553 -- Note that the reason we generate the conversion to the base
4554 -- type here is that we definitely want the range check to take
4555 -- place, even if it looks like the subtype is OK. Optimization
4556 -- considerations that allow us to omit the check have already
4557 -- been taken into account in the setting of the Do_Range_Check
4563 Num
:= New_List
(Make_Integer_Literal
(Loc
, Ind
));
4567 Make_Raise_Constraint_Error
(Loc
,
4571 Convert_To
(Base_Type
(Etype
(Sub
)),
4572 Duplicate_Subexpr_Move_Checks
(Sub
)),
4574 Make_Attribute_Reference
(Loc
,
4576 Duplicate_Subexpr_Move_Checks
(A
, Name_Req
=> True),
4577 Attribute_Name
=> Name_Range
,
4578 Expressions
=> Num
)),
4579 Reason
=> CE_Index_Check_Failed
));
4585 end Generate_Index_Checks
;
4587 --------------------------
4588 -- Generate_Range_Check --
4589 --------------------------
4591 procedure Generate_Range_Check
4593 Target_Type
: Entity_Id
;
4594 Reason
: RT_Exception_Code
)
4596 Loc
: constant Source_Ptr
:= Sloc
(N
);
4597 Source_Type
: constant Entity_Id
:= Etype
(N
);
4598 Source_Base_Type
: constant Entity_Id
:= Base_Type
(Source_Type
);
4599 Target_Base_Type
: constant Entity_Id
:= Base_Type
(Target_Type
);
4602 -- First special case, if the source type is already within the range
4603 -- of the target type, then no check is needed (probably we should have
4604 -- stopped Do_Range_Check from being set in the first place, but better
4605 -- late than later in preventing junk code!
4607 -- We do NOT apply this if the source node is a literal, since in this
4608 -- case the literal has already been labeled as having the subtype of
4611 if In_Subrange_Of
(Source_Type
, Target_Type
)
4613 (Nkind
(N
) = N_Integer_Literal
4615 Nkind
(N
) = N_Real_Literal
4617 Nkind
(N
) = N_Character_Literal
4620 and then Ekind
(Entity
(N
)) = E_Enumeration_Literal
))
4625 -- We need a check, so force evaluation of the node, so that it does
4626 -- not get evaluated twice (once for the check, once for the actual
4627 -- reference). Such a double evaluation is always a potential source
4628 -- of inefficiency, and is functionally incorrect in the volatile case.
4630 if not Is_Entity_Name
(N
)
4631 or else Treat_As_Volatile
(Entity
(N
))
4633 Force_Evaluation
(N
);
4636 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4637 -- the same since in this case we can simply do a direct check of the
4638 -- value of N against the bounds of Target_Type.
4640 -- [constraint_error when N not in Target_Type]
4642 -- Note: this is by far the most common case, for example all cases of
4643 -- checks on the RHS of assignments are in this category, but not all
4644 -- cases are like this. Notably conversions can involve two types.
4646 if Source_Base_Type
= Target_Base_Type
then
4648 Make_Raise_Constraint_Error
(Loc
,
4651 Left_Opnd
=> Duplicate_Subexpr
(N
),
4652 Right_Opnd
=> New_Occurrence_Of
(Target_Type
, Loc
)),
4655 -- Next test for the case where the target type is within the bounds
4656 -- of the base type of the source type, since in this case we can
4657 -- simply convert these bounds to the base type of T to do the test.
4659 -- [constraint_error when N not in
4660 -- Source_Base_Type (Target_Type'First)
4662 -- Source_Base_Type(Target_Type'Last))]
4664 -- The conversions will always work and need no check
4666 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
4667 -- of converting from an enumeration value to an integer type, such as
4668 -- occurs for the case of generating a range check on Enum'Val(Exp)
4669 -- (which used to be handled by gigi). This is OK, since the conversion
4670 -- itself does not require a check.
4672 elsif In_Subrange_Of
(Target_Type
, Source_Base_Type
) then
4674 Make_Raise_Constraint_Error
(Loc
,
4677 Left_Opnd
=> Duplicate_Subexpr
(N
),
4682 Unchecked_Convert_To
(Source_Base_Type
,
4683 Make_Attribute_Reference
(Loc
,
4685 New_Occurrence_Of
(Target_Type
, Loc
),
4686 Attribute_Name
=> Name_First
)),
4689 Unchecked_Convert_To
(Source_Base_Type
,
4690 Make_Attribute_Reference
(Loc
,
4692 New_Occurrence_Of
(Target_Type
, Loc
),
4693 Attribute_Name
=> Name_Last
)))),
4696 -- Note that at this stage we now that the Target_Base_Type is not in
4697 -- the range of the Source_Base_Type (since even the Target_Type itself
4698 -- is not in this range). It could still be the case that Source_Type is
4699 -- in range of the target base type since we have not checked that case.
4701 -- If that is the case, we can freely convert the source to the target,
4702 -- and then test the target result against the bounds.
4704 elsif In_Subrange_Of
(Source_Type
, Target_Base_Type
) then
4706 -- We make a temporary to hold the value of the converted value
4707 -- (converted to the base type), and then we will do the test against
4710 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4711 -- [constraint_error when Tnn not in Target_Type]
4713 -- Then the conversion itself is replaced by an occurrence of Tnn
4716 Tnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', N
);
4719 Insert_Actions
(N
, New_List
(
4720 Make_Object_Declaration
(Loc
,
4721 Defining_Identifier
=> Tnn
,
4722 Object_Definition
=>
4723 New_Occurrence_Of
(Target_Base_Type
, Loc
),
4724 Constant_Present
=> True,
4726 Make_Type_Conversion
(Loc
,
4727 Subtype_Mark
=> New_Occurrence_Of
(Target_Base_Type
, Loc
),
4728 Expression
=> Duplicate_Subexpr
(N
))),
4730 Make_Raise_Constraint_Error
(Loc
,
4733 Left_Opnd
=> New_Occurrence_Of
(Tnn
, Loc
),
4734 Right_Opnd
=> New_Occurrence_Of
(Target_Type
, Loc
)),
4736 Reason
=> Reason
)));
4738 Rewrite
(N
, New_Occurrence_Of
(Tnn
, Loc
));
4740 -- Set the type of N, because the declaration for Tnn might not
4741 -- be analyzed yet, as is the case if N appears within a record
4742 -- declaration, as a discriminant constraint or expression.
4744 Set_Etype
(N
, Target_Base_Type
);
4747 -- At this stage, we know that we have two scalar types, which are
4748 -- directly convertible, and where neither scalar type has a base
4749 -- range that is in the range of the other scalar type.
4751 -- The only way this can happen is with a signed and unsigned type.
4752 -- So test for these two cases:
4755 -- Case of the source is unsigned and the target is signed
4757 if Is_Unsigned_Type
(Source_Base_Type
)
4758 and then not Is_Unsigned_Type
(Target_Base_Type
)
4760 -- If the source is unsigned and the target is signed, then we
4761 -- know that the source is not shorter than the target (otherwise
4762 -- the source base type would be in the target base type range).
4764 -- In other words, the unsigned type is either the same size as
4765 -- the target, or it is larger. It cannot be smaller.
4768 (Esize
(Source_Base_Type
) >= Esize
(Target_Base_Type
));
4770 -- We only need to check the low bound if the low bound of the
4771 -- target type is non-negative. If the low bound of the target
4772 -- type is negative, then we know that we will fit fine.
4774 -- If the high bound of the target type is negative, then we
4775 -- know we have a constraint error, since we can't possibly
4776 -- have a negative source.
4778 -- With these two checks out of the way, we can do the check
4779 -- using the source type safely
4781 -- This is definitely the most annoying case!
4783 -- [constraint_error
4784 -- when (Target_Type'First >= 0
4786 -- N < Source_Base_Type (Target_Type'First))
4787 -- or else Target_Type'Last < 0
4788 -- or else N > Source_Base_Type (Target_Type'Last)];
4790 -- We turn off all checks since we know that the conversions
4791 -- will work fine, given the guards for negative values.
4794 Make_Raise_Constraint_Error
(Loc
,
4800 Left_Opnd
=> Make_Op_Ge
(Loc
,
4802 Make_Attribute_Reference
(Loc
,
4804 New_Occurrence_Of
(Target_Type
, Loc
),
4805 Attribute_Name
=> Name_First
),
4806 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
4810 Left_Opnd
=> Duplicate_Subexpr
(N
),
4812 Convert_To
(Source_Base_Type
,
4813 Make_Attribute_Reference
(Loc
,
4815 New_Occurrence_Of
(Target_Type
, Loc
),
4816 Attribute_Name
=> Name_First
)))),
4821 Make_Attribute_Reference
(Loc
,
4822 Prefix
=> New_Occurrence_Of
(Target_Type
, Loc
),
4823 Attribute_Name
=> Name_Last
),
4824 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
))),
4828 Left_Opnd
=> Duplicate_Subexpr
(N
),
4830 Convert_To
(Source_Base_Type
,
4831 Make_Attribute_Reference
(Loc
,
4832 Prefix
=> New_Occurrence_Of
(Target_Type
, Loc
),
4833 Attribute_Name
=> Name_Last
)))),
4836 Suppress
=> All_Checks
);
4838 -- Only remaining possibility is that the source is signed and
4839 -- the target is unsigned.
4842 pragma Assert
(not Is_Unsigned_Type
(Source_Base_Type
)
4843 and then Is_Unsigned_Type
(Target_Base_Type
));
4845 -- If the source is signed and the target is unsigned, then we
4846 -- know that the target is not shorter than the source (otherwise
4847 -- the target base type would be in the source base type range).
4849 -- In other words, the unsigned type is either the same size as
4850 -- the target, or it is larger. It cannot be smaller.
4852 -- Clearly we have an error if the source value is negative since
4853 -- no unsigned type can have negative values. If the source type
4854 -- is non-negative, then the check can be done using the target
4857 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4859 -- [constraint_error
4860 -- when N < 0 or else Tnn not in Target_Type];
4862 -- We turn off all checks for the conversion of N to the target
4863 -- base type, since we generate the explicit check to ensure that
4864 -- the value is non-negative
4867 Tnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', N
);
4870 Insert_Actions
(N
, New_List
(
4871 Make_Object_Declaration
(Loc
,
4872 Defining_Identifier
=> Tnn
,
4873 Object_Definition
=>
4874 New_Occurrence_Of
(Target_Base_Type
, Loc
),
4875 Constant_Present
=> True,
4877 Make_Unchecked_Type_Conversion
(Loc
,
4879 New_Occurrence_Of
(Target_Base_Type
, Loc
),
4880 Expression
=> Duplicate_Subexpr
(N
))),
4882 Make_Raise_Constraint_Error
(Loc
,
4887 Left_Opnd
=> Duplicate_Subexpr
(N
),
4888 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
4892 Left_Opnd
=> New_Occurrence_Of
(Tnn
, Loc
),
4894 New_Occurrence_Of
(Target_Type
, Loc
))),
4897 Suppress
=> All_Checks
);
4899 -- Set the Etype explicitly, because Insert_Actions may have
4900 -- placed the declaration in the freeze list for an enclosing
4901 -- construct, and thus it is not analyzed yet.
4903 Set_Etype
(Tnn
, Target_Base_Type
);
4904 Rewrite
(N
, New_Occurrence_Of
(Tnn
, Loc
));
4908 end Generate_Range_Check
;
4914 function Get_Check_Id
(N
: Name_Id
) return Check_Id
is
4916 -- For standard check name, we can do a direct computation
4918 if N
in First_Check_Name
.. Last_Check_Name
then
4919 return Check_Id
(N
- (First_Check_Name
- 1));
4921 -- For non-standard names added by pragma Check_Name, search table
4924 for J
in All_Checks
+ 1 .. Check_Names
.Last
loop
4925 if Check_Names
.Table
(J
) = N
then
4931 -- No matching name found
4936 ---------------------
4937 -- Get_Discriminal --
4938 ---------------------
4940 function Get_Discriminal
(E
: Entity_Id
; Bound
: Node_Id
) return Node_Id
is
4941 Loc
: constant Source_Ptr
:= Sloc
(E
);
4946 -- The bound can be a bona fide parameter of a protected operation,
4947 -- rather than a prival encoded as an in-parameter.
4949 if No
(Discriminal_Link
(Entity
(Bound
))) then
4953 -- Climb the scope stack looking for an enclosing protected type. If
4954 -- we run out of scopes, return the bound itself.
4957 while Present
(Sc
) loop
4958 if Sc
= Standard_Standard
then
4961 elsif Ekind
(Sc
) = E_Protected_Type
then
4968 D
:= First_Discriminant
(Sc
);
4969 while Present
(D
) loop
4970 if Chars
(D
) = Chars
(Bound
) then
4971 return New_Occurrence_Of
(Discriminal
(D
), Loc
);
4974 Next_Discriminant
(D
);
4978 end Get_Discriminal
;
4980 ----------------------
4981 -- Get_Range_Checks --
4982 ----------------------
4984 function Get_Range_Checks
4986 Target_Typ
: Entity_Id
;
4987 Source_Typ
: Entity_Id
:= Empty
;
4988 Warn_Node
: Node_Id
:= Empty
) return Check_Result
4991 return Selected_Range_Checks
4992 (Ck_Node
, Target_Typ
, Source_Typ
, Warn_Node
);
4993 end Get_Range_Checks
;
4999 function Guard_Access
5002 Ck_Node
: Node_Id
) return Node_Id
5005 if Nkind
(Cond
) = N_Or_Else
then
5006 Set_Paren_Count
(Cond
, 1);
5009 if Nkind
(Ck_Node
) = N_Allocator
then
5016 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
5017 Right_Opnd
=> Make_Null
(Loc
)),
5018 Right_Opnd
=> Cond
);
5022 -----------------------------
5023 -- Index_Checks_Suppressed --
5024 -----------------------------
5026 function Index_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5028 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
5029 return Is_Check_Suppressed
(E
, Index_Check
);
5031 return Scope_Suppress
(Index_Check
);
5033 end Index_Checks_Suppressed
;
5039 procedure Initialize
is
5041 for J
in Determine_Range_Cache_N
'Range loop
5042 Determine_Range_Cache_N
(J
) := Empty
;
5047 for J
in Int
range 1 .. All_Checks
loop
5048 Check_Names
.Append
(Name_Id
(Int
(First_Check_Name
) + J
- 1));
5052 -------------------------
5053 -- Insert_Range_Checks --
5054 -------------------------
5056 procedure Insert_Range_Checks
5057 (Checks
: Check_Result
;
5059 Suppress_Typ
: Entity_Id
;
5060 Static_Sloc
: Source_Ptr
:= No_Location
;
5061 Flag_Node
: Node_Id
:= Empty
;
5062 Do_Before
: Boolean := False)
5064 Internal_Flag_Node
: Node_Id
:= Flag_Node
;
5065 Internal_Static_Sloc
: Source_Ptr
:= Static_Sloc
;
5067 Check_Node
: Node_Id
;
5068 Checks_On
: constant Boolean :=
5069 (not Index_Checks_Suppressed
(Suppress_Typ
))
5071 (not Range_Checks_Suppressed
(Suppress_Typ
));
5074 -- For now we just return if Checks_On is false, however this should be
5075 -- enhanced to check for an always True value in the condition and to
5076 -- generate a compilation warning???
5078 if not Expander_Active
or else not Checks_On
then
5082 if Static_Sloc
= No_Location
then
5083 Internal_Static_Sloc
:= Sloc
(Node
);
5086 if No
(Flag_Node
) then
5087 Internal_Flag_Node
:= Node
;
5090 for J
in 1 .. 2 loop
5091 exit when No
(Checks
(J
));
5093 if Nkind
(Checks
(J
)) = N_Raise_Constraint_Error
5094 and then Present
(Condition
(Checks
(J
)))
5096 if not Has_Dynamic_Range_Check
(Internal_Flag_Node
) then
5097 Check_Node
:= Checks
(J
);
5098 Mark_Rewrite_Insertion
(Check_Node
);
5101 Insert_Before_And_Analyze
(Node
, Check_Node
);
5103 Insert_After_And_Analyze
(Node
, Check_Node
);
5106 Set_Has_Dynamic_Range_Check
(Internal_Flag_Node
);
5111 Make_Raise_Constraint_Error
(Internal_Static_Sloc
,
5112 Reason
=> CE_Range_Check_Failed
);
5113 Mark_Rewrite_Insertion
(Check_Node
);
5116 Insert_Before_And_Analyze
(Node
, Check_Node
);
5118 Insert_After_And_Analyze
(Node
, Check_Node
);
5122 end Insert_Range_Checks
;
5124 ------------------------
5125 -- Insert_Valid_Check --
5126 ------------------------
5128 procedure Insert_Valid_Check
(Expr
: Node_Id
) is
5129 Loc
: constant Source_Ptr
:= Sloc
(Expr
);
5133 -- Do not insert if checks off, or if not checking validity or
5134 -- if expression is known to be valid
5136 if not Validity_Checks_On
5137 or else Range_Or_Validity_Checks_Suppressed
(Expr
)
5138 or else Expr_Known_Valid
(Expr
)
5143 -- If we have a checked conversion, then validity check applies to
5144 -- the expression inside the conversion, not the result, since if
5145 -- the expression inside is valid, then so is the conversion result.
5148 while Nkind
(Exp
) = N_Type_Conversion
loop
5149 Exp
:= Expression
(Exp
);
5152 -- We are about to insert the validity check for Exp. We save and
5153 -- reset the Do_Range_Check flag over this validity check, and then
5154 -- put it back for the final original reference (Exp may be rewritten).
5157 DRC
: constant Boolean := Do_Range_Check
(Exp
);
5160 Set_Do_Range_Check
(Exp
, False);
5162 -- Force evaluation to avoid multiple reads for atomic/volatile
5164 if Is_Entity_Name
(Exp
)
5165 and then Is_Volatile
(Entity
(Exp
))
5167 Force_Evaluation
(Exp
, Name_Req
=> True);
5170 -- Insert the validity check. Note that we do this with validity
5171 -- checks turned off, to avoid recursion, we do not want validity
5172 -- checks on the validity checking code itself!
5176 Make_Raise_Constraint_Error
(Loc
,
5180 Make_Attribute_Reference
(Loc
,
5182 Duplicate_Subexpr_No_Checks
(Exp
, Name_Req
=> True),
5183 Attribute_Name
=> Name_Valid
)),
5184 Reason
=> CE_Invalid_Data
),
5185 Suppress
=> Validity_Check
);
5187 -- If the expression is a a reference to an element of a bit-packed
5188 -- array, then it is rewritten as a renaming declaration. If the
5189 -- expression is an actual in a call, it has not been expanded,
5190 -- waiting for the proper point at which to do it. The same happens
5191 -- with renamings, so that we have to force the expansion now. This
5192 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5195 if Is_Entity_Name
(Exp
)
5196 and then Nkind
(Parent
(Entity
(Exp
))) =
5197 N_Object_Renaming_Declaration
5200 Old_Exp
: constant Node_Id
:= Name
(Parent
(Entity
(Exp
)));
5202 if Nkind
(Old_Exp
) = N_Indexed_Component
5203 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Old_Exp
)))
5205 Expand_Packed_Element_Reference
(Old_Exp
);
5210 -- Put back the Do_Range_Check flag on the resulting (possibly
5211 -- rewritten) expression.
5213 -- Note: it might be thought that a validity check is not required
5214 -- when a range check is present, but that's not the case, because
5215 -- the back end is allowed to assume for the range check that the
5216 -- operand is within its declared range (an assumption that validity
5217 -- checking is all about NOT assuming!)
5219 -- Note: no need to worry about Possible_Local_Raise here, it will
5220 -- already have been called if original node has Do_Range_Check set.
5222 Set_Do_Range_Check
(Exp
, DRC
);
5224 end Insert_Valid_Check
;
5226 ----------------------------------
5227 -- Install_Null_Excluding_Check --
5228 ----------------------------------
5230 procedure Install_Null_Excluding_Check
(N
: Node_Id
) is
5231 Loc
: constant Source_Ptr
:= Sloc
(N
);
5232 Typ
: constant Entity_Id
:= Etype
(N
);
5234 function Safe_To_Capture_In_Parameter_Value
return Boolean;
5235 -- Determines if it is safe to capture Known_Non_Null status for an
5236 -- the entity referenced by node N. The caller ensures that N is indeed
5237 -- an entity name. It is safe to capture the non-null status for an IN
5238 -- parameter when the reference occurs within a declaration that is sure
5239 -- to be executed as part of the declarative region.
5241 procedure Mark_Non_Null
;
5242 -- After installation of check, if the node in question is an entity
5243 -- name, then mark this entity as non-null if possible.
5245 function Safe_To_Capture_In_Parameter_Value
return Boolean is
5246 E
: constant Entity_Id
:= Entity
(N
);
5247 S
: constant Entity_Id
:= Current_Scope
;
5251 if Ekind
(E
) /= E_In_Parameter
then
5255 -- Two initial context checks. We must be inside a subprogram body
5256 -- with declarations and reference must not appear in nested scopes.
5258 if (Ekind
(S
) /= E_Function
and then Ekind
(S
) /= E_Procedure
)
5259 or else Scope
(E
) /= S
5264 S_Par
:= Parent
(Parent
(S
));
5266 if Nkind
(S_Par
) /= N_Subprogram_Body
5267 or else No
(Declarations
(S_Par
))
5277 -- Retrieve the declaration node of N (if any). Note that N
5278 -- may be a part of a complex initialization expression.
5282 while Present
(P
) loop
5284 -- If we have a short circuit form, and we are within the right
5285 -- hand expression, we return false, since the right hand side
5286 -- is not guaranteed to be elaborated.
5288 if Nkind
(P
) in N_Short_Circuit
5289 and then N
= Right_Opnd
(P
)
5294 -- Similarly, if we are in a conditional expression and not
5295 -- part of the condition, then we return False, since neither
5296 -- the THEN or ELSE expressions will always be elaborated.
5298 if Nkind
(P
) = N_Conditional_Expression
5299 and then N
/= First
(Expressions
(P
))
5304 -- If we are in a case eexpression, and not part of the
5305 -- expression, then we return False, since a particular
5306 -- branch may not always be elaborated
5308 if Nkind
(P
) = N_Case_Expression
5309 and then N
/= Expression
(P
)
5314 -- While traversing the parent chain, we find that N
5315 -- belongs to a statement, thus it may never appear in
5316 -- a declarative region.
5318 if Nkind
(P
) in N_Statement_Other_Than_Procedure_Call
5319 or else Nkind
(P
) = N_Procedure_Call_Statement
5324 -- If we are at a declaration, record it and exit
5326 if Nkind
(P
) in N_Declaration
5327 and then Nkind
(P
) not in N_Subprogram_Specification
5340 return List_Containing
(N_Decl
) = Declarations
(S_Par
);
5342 end Safe_To_Capture_In_Parameter_Value
;
5348 procedure Mark_Non_Null
is
5350 -- Only case of interest is if node N is an entity name
5352 if Is_Entity_Name
(N
) then
5354 -- For sure, we want to clear an indication that this is known to
5355 -- be null, since if we get past this check, it definitely is not!
5357 Set_Is_Known_Null
(Entity
(N
), False);
5359 -- We can mark the entity as known to be non-null if either it is
5360 -- safe to capture the value, or in the case of an IN parameter,
5361 -- which is a constant, if the check we just installed is in the
5362 -- declarative region of the subprogram body. In this latter case,
5363 -- a check is decisive for the rest of the body if the expression
5364 -- is sure to be elaborated, since we know we have to elaborate
5365 -- all declarations before executing the body.
5367 -- Couldn't this always be part of Safe_To_Capture_Value ???
5369 if Safe_To_Capture_Value
(N
, Entity
(N
))
5370 or else Safe_To_Capture_In_Parameter_Value
5372 Set_Is_Known_Non_Null
(Entity
(N
));
5377 -- Start of processing for Install_Null_Excluding_Check
5380 pragma Assert
(Is_Access_Type
(Typ
));
5382 -- No check inside a generic (why not???)
5384 if Inside_A_Generic
then
5388 -- No check needed if known to be non-null
5390 if Known_Non_Null
(N
) then
5394 -- If known to be null, here is where we generate a compile time check
5396 if Known_Null
(N
) then
5398 -- Avoid generating warning message inside init procs
5400 if not Inside_Init_Proc
then
5401 Apply_Compile_Time_Constraint_Error
5403 "null value not allowed here?",
5404 CE_Access_Check_Failed
);
5407 Make_Raise_Constraint_Error
(Loc
,
5408 Reason
=> CE_Access_Check_Failed
));
5415 -- If entity is never assigned, for sure a warning is appropriate
5417 if Is_Entity_Name
(N
) then
5418 Check_Unset_Reference
(N
);
5421 -- No check needed if checks are suppressed on the range. Note that we
5422 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5423 -- so, since the program is erroneous, but we don't like to casually
5424 -- propagate such conclusions from erroneosity).
5426 if Access_Checks_Suppressed
(Typ
) then
5430 -- No check needed for access to concurrent record types generated by
5431 -- the expander. This is not just an optimization (though it does indeed
5432 -- remove junk checks). It also avoids generation of junk warnings.
5434 if Nkind
(N
) in N_Has_Chars
5435 and then Chars
(N
) = Name_uObject
5436 and then Is_Concurrent_Record_Type
5437 (Directly_Designated_Type
(Etype
(N
)))
5442 -- Otherwise install access check
5445 Make_Raise_Constraint_Error
(Loc
,
5448 Left_Opnd
=> Duplicate_Subexpr_Move_Checks
(N
),
5449 Right_Opnd
=> Make_Null
(Loc
)),
5450 Reason
=> CE_Access_Check_Failed
));
5453 end Install_Null_Excluding_Check
;
5455 --------------------------
5456 -- Install_Static_Check --
5457 --------------------------
5459 procedure Install_Static_Check
(R_Cno
: Node_Id
; Loc
: Source_Ptr
) is
5460 Stat
: constant Boolean := Is_Static_Expression
(R_Cno
);
5461 Typ
: constant Entity_Id
:= Etype
(R_Cno
);
5465 Make_Raise_Constraint_Error
(Loc
,
5466 Reason
=> CE_Range_Check_Failed
));
5467 Set_Analyzed
(R_Cno
);
5468 Set_Etype
(R_Cno
, Typ
);
5469 Set_Raises_Constraint_Error
(R_Cno
);
5470 Set_Is_Static_Expression
(R_Cno
, Stat
);
5472 -- Now deal with possible local raise handling
5474 Possible_Local_Raise
(R_Cno
, Standard_Constraint_Error
);
5475 end Install_Static_Check
;
5477 ---------------------
5478 -- Kill_All_Checks --
5479 ---------------------
5481 procedure Kill_All_Checks
is
5483 if Debug_Flag_CC
then
5484 w
("Kill_All_Checks");
5487 -- We reset the number of saved checks to zero, and also modify all
5488 -- stack entries for statement ranges to indicate that the number of
5489 -- checks at each level is now zero.
5491 Num_Saved_Checks
:= 0;
5493 -- Note: the Int'Min here avoids any possibility of J being out of
5494 -- range when called from e.g. Conditional_Statements_Begin.
5496 for J
in 1 .. Int
'Min (Saved_Checks_TOS
, Saved_Checks_Stack
'Last) loop
5497 Saved_Checks_Stack
(J
) := 0;
5499 end Kill_All_Checks
;
5505 procedure Kill_Checks
(V
: Entity_Id
) is
5507 if Debug_Flag_CC
then
5508 w
("Kill_Checks for entity", Int
(V
));
5511 for J
in 1 .. Num_Saved_Checks
loop
5512 if Saved_Checks
(J
).Entity
= V
then
5513 if Debug_Flag_CC
then
5514 w
(" Checks killed for saved check ", J
);
5517 Saved_Checks
(J
).Killed
:= True;
5522 ------------------------------
5523 -- Length_Checks_Suppressed --
5524 ------------------------------
5526 function Length_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5528 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
5529 return Is_Check_Suppressed
(E
, Length_Check
);
5531 return Scope_Suppress
(Length_Check
);
5533 end Length_Checks_Suppressed
;
5535 --------------------------------
5536 -- Overflow_Checks_Suppressed --
5537 --------------------------------
5539 function Overflow_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5541 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
5542 return Is_Check_Suppressed
(E
, Overflow_Check
);
5544 return Scope_Suppress
(Overflow_Check
);
5546 end Overflow_Checks_Suppressed
;
5548 -----------------------------
5549 -- Range_Checks_Suppressed --
5550 -----------------------------
5552 function Range_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5556 -- Note: for now we always suppress range checks on Vax float types,
5557 -- since Gigi does not know how to generate these checks.
5559 if Vax_Float
(E
) then
5561 elsif Kill_Range_Checks
(E
) then
5563 elsif Checks_May_Be_Suppressed
(E
) then
5564 return Is_Check_Suppressed
(E
, Range_Check
);
5568 return Scope_Suppress
(Range_Check
);
5569 end Range_Checks_Suppressed
;
5571 -----------------------------------------
5572 -- Range_Or_Validity_Checks_Suppressed --
5573 -----------------------------------------
5575 -- Note: the coding would be simpler here if we simply made appropriate
5576 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5577 -- duplicated checks which we prefer to avoid.
5579 function Range_Or_Validity_Checks_Suppressed
5580 (Expr
: Node_Id
) return Boolean
5583 -- Immediate return if scope checks suppressed for either check
5585 if Scope_Suppress
(Range_Check
) or Scope_Suppress
(Validity_Check
) then
5589 -- If no expression, that's odd, decide that checks are suppressed,
5590 -- since we don't want anyone trying to do checks in this case, which
5591 -- is most likely the result of some other error.
5597 -- Expression is present, so perform suppress checks on type
5600 Typ
: constant Entity_Id
:= Etype
(Expr
);
5602 if Vax_Float
(Typ
) then
5604 elsif Checks_May_Be_Suppressed
(Typ
)
5605 and then (Is_Check_Suppressed
(Typ
, Range_Check
)
5607 Is_Check_Suppressed
(Typ
, Validity_Check
))
5613 -- If expression is an entity name, perform checks on this entity
5615 if Is_Entity_Name
(Expr
) then
5617 Ent
: constant Entity_Id
:= Entity
(Expr
);
5619 if Checks_May_Be_Suppressed
(Ent
) then
5620 return Is_Check_Suppressed
(Ent
, Range_Check
)
5621 or else Is_Check_Suppressed
(Ent
, Validity_Check
);
5626 -- If we fall through, no checks suppressed
5629 end Range_Or_Validity_Checks_Suppressed
;
5635 procedure Remove_Checks
(Expr
: Node_Id
) is
5636 function Process
(N
: Node_Id
) return Traverse_Result
;
5637 -- Process a single node during the traversal
5639 procedure Traverse
is new Traverse_Proc
(Process
);
5640 -- The traversal procedure itself
5646 function Process
(N
: Node_Id
) return Traverse_Result
is
5648 if Nkind
(N
) not in N_Subexpr
then
5652 Set_Do_Range_Check
(N
, False);
5656 Traverse
(Left_Opnd
(N
));
5659 when N_Attribute_Reference
=>
5660 Set_Do_Overflow_Check
(N
, False);
5662 when N_Function_Call
=>
5663 Set_Do_Tag_Check
(N
, False);
5666 Set_Do_Overflow_Check
(N
, False);
5670 Set_Do_Division_Check
(N
, False);
5673 Set_Do_Length_Check
(N
, False);
5676 Set_Do_Division_Check
(N
, False);
5679 Set_Do_Length_Check
(N
, False);
5682 Set_Do_Division_Check
(N
, False);
5685 Set_Do_Length_Check
(N
, False);
5692 Traverse
(Left_Opnd
(N
));
5695 when N_Selected_Component
=>
5696 Set_Do_Discriminant_Check
(N
, False);
5698 when N_Type_Conversion
=>
5699 Set_Do_Length_Check
(N
, False);
5700 Set_Do_Tag_Check
(N
, False);
5701 Set_Do_Overflow_Check
(N
, False);
5710 -- Start of processing for Remove_Checks
5716 ----------------------------
5717 -- Selected_Length_Checks --
5718 ----------------------------
5720 function Selected_Length_Checks
5722 Target_Typ
: Entity_Id
;
5723 Source_Typ
: Entity_Id
;
5724 Warn_Node
: Node_Id
) return Check_Result
5726 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
5729 Expr_Actual
: Node_Id
;
5731 Cond
: Node_Id
:= Empty
;
5732 Do_Access
: Boolean := False;
5733 Wnode
: Node_Id
:= Warn_Node
;
5734 Ret_Result
: Check_Result
:= (Empty
, Empty
);
5735 Num_Checks
: Natural := 0;
5737 procedure Add_Check
(N
: Node_Id
);
5738 -- Adds the action given to Ret_Result if N is non-Empty
5740 function Get_E_Length
(E
: Entity_Id
; Indx
: Nat
) return Node_Id
;
5741 function Get_N_Length
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
5742 -- Comments required ???
5744 function Same_Bounds
(L
: Node_Id
; R
: Node_Id
) return Boolean;
5745 -- True for equal literals and for nodes that denote the same constant
5746 -- entity, even if its value is not a static constant. This includes the
5747 -- case of a discriminal reference within an init proc. Removes some
5748 -- obviously superfluous checks.
5750 function Length_E_Cond
5751 (Exptyp
: Entity_Id
;
5753 Indx
: Nat
) return Node_Id
;
5754 -- Returns expression to compute:
5755 -- Typ'Length /= Exptyp'Length
5757 function Length_N_Cond
5760 Indx
: Nat
) return Node_Id
;
5761 -- Returns expression to compute:
5762 -- Typ'Length /= Expr'Length
5768 procedure Add_Check
(N
: Node_Id
) is
5772 -- For now, ignore attempt to place more than 2 checks ???
5774 if Num_Checks
= 2 then
5778 pragma Assert
(Num_Checks
<= 1);
5779 Num_Checks
:= Num_Checks
+ 1;
5780 Ret_Result
(Num_Checks
) := N
;
5788 function Get_E_Length
(E
: Entity_Id
; Indx
: Nat
) return Node_Id
is
5789 SE
: constant Entity_Id
:= Scope
(E
);
5791 E1
: Entity_Id
:= E
;
5794 if Ekind
(Scope
(E
)) = E_Record_Type
5795 and then Has_Discriminants
(Scope
(E
))
5797 N
:= Build_Discriminal_Subtype_Of_Component
(E
);
5800 Insert_Action
(Ck_Node
, N
);
5801 E1
:= Defining_Identifier
(N
);
5805 if Ekind
(E1
) = E_String_Literal_Subtype
then
5807 Make_Integer_Literal
(Loc
,
5808 Intval
=> String_Literal_Length
(E1
));
5810 elsif SE
/= Standard_Standard
5811 and then Ekind
(Scope
(SE
)) = E_Protected_Type
5812 and then Has_Discriminants
(Scope
(SE
))
5813 and then Has_Completion
(Scope
(SE
))
5814 and then not Inside_Init_Proc
5816 -- If the type whose length is needed is a private component
5817 -- constrained by a discriminant, we must expand the 'Length
5818 -- attribute into an explicit computation, using the discriminal
5819 -- of the current protected operation. This is because the actual
5820 -- type of the prival is constructed after the protected opera-
5821 -- tion has been fully expanded.
5824 Indx_Type
: Node_Id
;
5827 Do_Expand
: Boolean := False;
5830 Indx_Type
:= First_Index
(E
);
5832 for J
in 1 .. Indx
- 1 loop
5833 Next_Index
(Indx_Type
);
5836 Get_Index_Bounds
(Indx_Type
, Lo
, Hi
);
5838 if Nkind
(Lo
) = N_Identifier
5839 and then Ekind
(Entity
(Lo
)) = E_In_Parameter
5841 Lo
:= Get_Discriminal
(E
, Lo
);
5845 if Nkind
(Hi
) = N_Identifier
5846 and then Ekind
(Entity
(Hi
)) = E_In_Parameter
5848 Hi
:= Get_Discriminal
(E
, Hi
);
5853 if not Is_Entity_Name
(Lo
) then
5854 Lo
:= Duplicate_Subexpr_No_Checks
(Lo
);
5857 if not Is_Entity_Name
(Hi
) then
5858 Lo
:= Duplicate_Subexpr_No_Checks
(Hi
);
5864 Make_Op_Subtract
(Loc
,
5868 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1));
5873 Make_Attribute_Reference
(Loc
,
5874 Attribute_Name
=> Name_Length
,
5876 New_Occurrence_Of
(E1
, Loc
));
5879 Set_Expressions
(N
, New_List
(
5880 Make_Integer_Literal
(Loc
, Indx
)));
5889 Make_Attribute_Reference
(Loc
,
5890 Attribute_Name
=> Name_Length
,
5892 New_Occurrence_Of
(E1
, Loc
));
5895 Set_Expressions
(N
, New_List
(
5896 Make_Integer_Literal
(Loc
, Indx
)));
5907 function Get_N_Length
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
5910 Make_Attribute_Reference
(Loc
,
5911 Attribute_Name
=> Name_Length
,
5913 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
5914 Expressions
=> New_List
(
5915 Make_Integer_Literal
(Loc
, Indx
)));
5922 function Length_E_Cond
5923 (Exptyp
: Entity_Id
;
5925 Indx
: Nat
) return Node_Id
5930 Left_Opnd
=> Get_E_Length
(Typ
, Indx
),
5931 Right_Opnd
=> Get_E_Length
(Exptyp
, Indx
));
5938 function Length_N_Cond
5941 Indx
: Nat
) return Node_Id
5946 Left_Opnd
=> Get_E_Length
(Typ
, Indx
),
5947 Right_Opnd
=> Get_N_Length
(Expr
, Indx
));
5954 function Same_Bounds
(L
: Node_Id
; R
: Node_Id
) return Boolean is
5957 (Nkind
(L
) = N_Integer_Literal
5958 and then Nkind
(R
) = N_Integer_Literal
5959 and then Intval
(L
) = Intval
(R
))
5963 and then Ekind
(Entity
(L
)) = E_Constant
5964 and then ((Is_Entity_Name
(R
)
5965 and then Entity
(L
) = Entity
(R
))
5967 (Nkind
(R
) = N_Type_Conversion
5968 and then Is_Entity_Name
(Expression
(R
))
5969 and then Entity
(L
) = Entity
(Expression
(R
)))))
5973 and then Ekind
(Entity
(R
)) = E_Constant
5974 and then Nkind
(L
) = N_Type_Conversion
5975 and then Is_Entity_Name
(Expression
(L
))
5976 and then Entity
(R
) = Entity
(Expression
(L
)))
5980 and then Is_Entity_Name
(R
)
5981 and then Entity
(L
) = Entity
(R
)
5982 and then Ekind
(Entity
(L
)) = E_In_Parameter
5983 and then Inside_Init_Proc
);
5986 -- Start of processing for Selected_Length_Checks
5989 if not Expander_Active
then
5993 if Target_Typ
= Any_Type
5994 or else Target_Typ
= Any_Composite
5995 or else Raises_Constraint_Error
(Ck_Node
)
6004 T_Typ
:= Target_Typ
;
6006 if No
(Source_Typ
) then
6007 S_Typ
:= Etype
(Ck_Node
);
6009 S_Typ
:= Source_Typ
;
6012 if S_Typ
= Any_Type
or else S_Typ
= Any_Composite
then
6016 if Is_Access_Type
(T_Typ
) and then Is_Access_Type
(S_Typ
) then
6017 S_Typ
:= Designated_Type
(S_Typ
);
6018 T_Typ
:= Designated_Type
(T_Typ
);
6021 -- A simple optimization for the null case
6023 if Known_Null
(Ck_Node
) then
6028 if Is_Array_Type
(T_Typ
) and then Is_Array_Type
(S_Typ
) then
6029 if Is_Constrained
(T_Typ
) then
6031 -- The checking code to be generated will freeze the
6032 -- corresponding array type. However, we must freeze the
6033 -- type now, so that the freeze node does not appear within
6034 -- the generated condional expression, but ahead of it.
6036 Freeze_Before
(Ck_Node
, T_Typ
);
6038 Expr_Actual
:= Get_Referenced_Object
(Ck_Node
);
6039 Exptyp
:= Get_Actual_Subtype
(Ck_Node
);
6041 if Is_Access_Type
(Exptyp
) then
6042 Exptyp
:= Designated_Type
(Exptyp
);
6045 -- String_Literal case. This needs to be handled specially be-
6046 -- cause no index types are available for string literals. The
6047 -- condition is simply:
6049 -- T_Typ'Length = string-literal-length
6051 if Nkind
(Expr_Actual
) = N_String_Literal
6052 and then Ekind
(Etype
(Expr_Actual
)) = E_String_Literal_Subtype
6056 Left_Opnd
=> Get_E_Length
(T_Typ
, 1),
6058 Make_Integer_Literal
(Loc
,
6060 String_Literal_Length
(Etype
(Expr_Actual
))));
6062 -- General array case. Here we have a usable actual subtype for
6063 -- the expression, and the condition is built from the two types
6066 -- T_Typ'Length /= Exptyp'Length or else
6067 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
6068 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
6071 elsif Is_Constrained
(Exptyp
) then
6073 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
6086 -- At the library level, we need to ensure that the type of
6087 -- the object is elaborated before the check itself is
6088 -- emitted. This is only done if the object is in the
6089 -- current compilation unit, otherwise the type is frozen
6090 -- and elaborated in its unit.
6092 if Is_Itype
(Exptyp
)
6094 Ekind
(Cunit_Entity
(Current_Sem_Unit
)) = E_Package
6096 not In_Package_Body
(Cunit_Entity
(Current_Sem_Unit
))
6097 and then In_Open_Scopes
(Scope
(Exptyp
))
6099 Ref_Node
:= Make_Itype_Reference
(Sloc
(Ck_Node
));
6100 Set_Itype
(Ref_Node
, Exptyp
);
6101 Insert_Action
(Ck_Node
, Ref_Node
);
6104 L_Index
:= First_Index
(T_Typ
);
6105 R_Index
:= First_Index
(Exptyp
);
6107 for Indx
in 1 .. Ndims
loop
6108 if not (Nkind
(L_Index
) = N_Raise_Constraint_Error
6110 Nkind
(R_Index
) = N_Raise_Constraint_Error
)
6112 Get_Index_Bounds
(L_Index
, L_Low
, L_High
);
6113 Get_Index_Bounds
(R_Index
, R_Low
, R_High
);
6115 -- Deal with compile time length check. Note that we
6116 -- skip this in the access case, because the access
6117 -- value may be null, so we cannot know statically.
6120 and then Compile_Time_Known_Value
(L_Low
)
6121 and then Compile_Time_Known_Value
(L_High
)
6122 and then Compile_Time_Known_Value
(R_Low
)
6123 and then Compile_Time_Known_Value
(R_High
)
6125 if Expr_Value
(L_High
) >= Expr_Value
(L_Low
) then
6126 L_Length
:= Expr_Value
(L_High
) -
6127 Expr_Value
(L_Low
) + 1;
6129 L_Length
:= UI_From_Int
(0);
6132 if Expr_Value
(R_High
) >= Expr_Value
(R_Low
) then
6133 R_Length
:= Expr_Value
(R_High
) -
6134 Expr_Value
(R_Low
) + 1;
6136 R_Length
:= UI_From_Int
(0);
6139 if L_Length
> R_Length
then
6141 (Compile_Time_Constraint_Error
6142 (Wnode
, "too few elements for}?", T_Typ
));
6144 elsif L_Length
< R_Length
then
6146 (Compile_Time_Constraint_Error
6147 (Wnode
, "too many elements for}?", T_Typ
));
6150 -- The comparison for an individual index subtype
6151 -- is omitted if the corresponding index subtypes
6152 -- statically match, since the result is known to
6153 -- be true. Note that this test is worth while even
6154 -- though we do static evaluation, because non-static
6155 -- subtypes can statically match.
6158 Subtypes_Statically_Match
6159 (Etype
(L_Index
), Etype
(R_Index
))
6162 (Same_Bounds
(L_Low
, R_Low
)
6163 and then Same_Bounds
(L_High
, R_High
))
6166 (Cond
, Length_E_Cond
(Exptyp
, T_Typ
, Indx
));
6175 -- Handle cases where we do not get a usable actual subtype that
6176 -- is constrained. This happens for example in the function call
6177 -- and explicit dereference cases. In these cases, we have to get
6178 -- the length or range from the expression itself, making sure we
6179 -- do not evaluate it more than once.
6181 -- Here Ck_Node is the original expression, or more properly the
6182 -- result of applying Duplicate_Expr to the original tree, forcing
6183 -- the result to be a name.
6187 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
6190 -- Build the condition for the explicit dereference case
6192 for Indx
in 1 .. Ndims
loop
6194 (Cond
, Length_N_Cond
(Ck_Node
, T_Typ
, Indx
));
6201 -- Construct the test and insert into the tree
6203 if Present
(Cond
) then
6205 Cond
:= Guard_Access
(Cond
, Loc
, Ck_Node
);
6209 (Make_Raise_Constraint_Error
(Loc
,
6211 Reason
=> CE_Length_Check_Failed
));
6215 end Selected_Length_Checks
;
6217 ---------------------------
6218 -- Selected_Range_Checks --
6219 ---------------------------
6221 function Selected_Range_Checks
6223 Target_Typ
: Entity_Id
;
6224 Source_Typ
: Entity_Id
;
6225 Warn_Node
: Node_Id
) return Check_Result
6227 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
6230 Expr_Actual
: Node_Id
;
6232 Cond
: Node_Id
:= Empty
;
6233 Do_Access
: Boolean := False;
6234 Wnode
: Node_Id
:= Warn_Node
;
6235 Ret_Result
: Check_Result
:= (Empty
, Empty
);
6236 Num_Checks
: Integer := 0;
6238 procedure Add_Check
(N
: Node_Id
);
6239 -- Adds the action given to Ret_Result if N is non-Empty
6241 function Discrete_Range_Cond
6243 Typ
: Entity_Id
) return Node_Id
;
6244 -- Returns expression to compute:
6245 -- Low_Bound (Expr) < Typ'First
6247 -- High_Bound (Expr) > Typ'Last
6249 function Discrete_Expr_Cond
6251 Typ
: Entity_Id
) return Node_Id
;
6252 -- Returns expression to compute:
6257 function Get_E_First_Or_Last
6261 Nam
: Name_Id
) return Node_Id
;
6262 -- Returns an attribute reference
6263 -- E'First or E'Last
6264 -- with a source location of Loc.
6266 -- Nam is Name_First or Name_Last, according to which attribute is
6267 -- desired. If Indx is non-zero, it is passed as a literal in the
6268 -- Expressions of the attribute reference (identifying the desired
6269 -- array dimension).
6271 function Get_N_First
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
6272 function Get_N_Last
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
6273 -- Returns expression to compute:
6274 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6276 function Range_E_Cond
6277 (Exptyp
: Entity_Id
;
6281 -- Returns expression to compute:
6282 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6284 function Range_Equal_E_Cond
6285 (Exptyp
: Entity_Id
;
6287 Indx
: Nat
) return Node_Id
;
6288 -- Returns expression to compute:
6289 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6291 function Range_N_Cond
6294 Indx
: Nat
) return Node_Id
;
6295 -- Return expression to compute:
6296 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6302 procedure Add_Check
(N
: Node_Id
) is
6306 -- For now, ignore attempt to place more than 2 checks ???
6308 if Num_Checks
= 2 then
6312 pragma Assert
(Num_Checks
<= 1);
6313 Num_Checks
:= Num_Checks
+ 1;
6314 Ret_Result
(Num_Checks
) := N
;
6318 -------------------------
6319 -- Discrete_Expr_Cond --
6320 -------------------------
6322 function Discrete_Expr_Cond
6324 Typ
: Entity_Id
) return Node_Id
6332 Convert_To
(Base_Type
(Typ
),
6333 Duplicate_Subexpr_No_Checks
(Expr
)),
6335 Convert_To
(Base_Type
(Typ
),
6336 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_First
))),
6341 Convert_To
(Base_Type
(Typ
),
6342 Duplicate_Subexpr_No_Checks
(Expr
)),
6346 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_Last
))));
6347 end Discrete_Expr_Cond
;
6349 -------------------------
6350 -- Discrete_Range_Cond --
6351 -------------------------
6353 function Discrete_Range_Cond
6355 Typ
: Entity_Id
) return Node_Id
6357 LB
: Node_Id
:= Low_Bound
(Expr
);
6358 HB
: Node_Id
:= High_Bound
(Expr
);
6360 Left_Opnd
: Node_Id
;
6361 Right_Opnd
: Node_Id
;
6364 if Nkind
(LB
) = N_Identifier
6365 and then Ekind
(Entity
(LB
)) = E_Discriminant
6367 LB
:= New_Occurrence_Of
(Discriminal
(Entity
(LB
)), Loc
);
6370 if Nkind
(HB
) = N_Identifier
6371 and then Ekind
(Entity
(HB
)) = E_Discriminant
6373 HB
:= New_Occurrence_Of
(Discriminal
(Entity
(HB
)), Loc
);
6380 (Base_Type
(Typ
), Duplicate_Subexpr_No_Checks
(LB
)),
6385 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_First
)));
6387 if Base_Type
(Typ
) = Typ
then
6390 elsif Compile_Time_Known_Value
(High_Bound
(Scalar_Range
(Typ
)))
6392 Compile_Time_Known_Value
(High_Bound
(Scalar_Range
6395 if Is_Floating_Point_Type
(Typ
) then
6396 if Expr_Value_R
(High_Bound
(Scalar_Range
(Typ
))) =
6397 Expr_Value_R
(High_Bound
(Scalar_Range
(Base_Type
(Typ
))))
6403 if Expr_Value
(High_Bound
(Scalar_Range
(Typ
))) =
6404 Expr_Value
(High_Bound
(Scalar_Range
(Base_Type
(Typ
))))
6415 (Base_Type
(Typ
), Duplicate_Subexpr_No_Checks
(HB
)),
6420 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_Last
)));
6422 return Make_Or_Else
(Loc
, Left_Opnd
, Right_Opnd
);
6423 end Discrete_Range_Cond
;
6425 -------------------------
6426 -- Get_E_First_Or_Last --
6427 -------------------------
6429 function Get_E_First_Or_Last
6433 Nam
: Name_Id
) return Node_Id
6438 Exprs
:= New_List
(Make_Integer_Literal
(Loc
, UI_From_Int
(Indx
)));
6443 return Make_Attribute_Reference
(Loc
,
6444 Prefix
=> New_Occurrence_Of
(E
, Loc
),
6445 Attribute_Name
=> Nam
,
6446 Expressions
=> Exprs
);
6447 end Get_E_First_Or_Last
;
6453 function Get_N_First
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
6456 Make_Attribute_Reference
(Loc
,
6457 Attribute_Name
=> Name_First
,
6459 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
6460 Expressions
=> New_List
(
6461 Make_Integer_Literal
(Loc
, Indx
)));
6468 function Get_N_Last
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
6471 Make_Attribute_Reference
(Loc
,
6472 Attribute_Name
=> Name_Last
,
6474 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
6475 Expressions
=> New_List
(
6476 Make_Integer_Literal
(Loc
, Indx
)));
6483 function Range_E_Cond
6484 (Exptyp
: Entity_Id
;
6486 Indx
: Nat
) return Node_Id
6494 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_First
),
6496 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
6501 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_Last
),
6503 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
6506 ------------------------
6507 -- Range_Equal_E_Cond --
6508 ------------------------
6510 function Range_Equal_E_Cond
6511 (Exptyp
: Entity_Id
;
6513 Indx
: Nat
) return Node_Id
6521 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_First
),
6523 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
6528 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_Last
),
6530 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
6531 end Range_Equal_E_Cond
;
6537 function Range_N_Cond
6540 Indx
: Nat
) return Node_Id
6548 Get_N_First
(Expr
, Indx
),
6550 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
6555 Get_N_Last
(Expr
, Indx
),
6557 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
6560 -- Start of processing for Selected_Range_Checks
6563 if not Expander_Active
then
6567 if Target_Typ
= Any_Type
6568 or else Target_Typ
= Any_Composite
6569 or else Raises_Constraint_Error
(Ck_Node
)
6578 T_Typ
:= Target_Typ
;
6580 if No
(Source_Typ
) then
6581 S_Typ
:= Etype
(Ck_Node
);
6583 S_Typ
:= Source_Typ
;
6586 if S_Typ
= Any_Type
or else S_Typ
= Any_Composite
then
6590 -- The order of evaluating T_Typ before S_Typ seems to be critical
6591 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6592 -- in, and since Node can be an N_Range node, it might be invalid.
6593 -- Should there be an assert check somewhere for taking the Etype of
6594 -- an N_Range node ???
6596 if Is_Access_Type
(T_Typ
) and then Is_Access_Type
(S_Typ
) then
6597 S_Typ
:= Designated_Type
(S_Typ
);
6598 T_Typ
:= Designated_Type
(T_Typ
);
6601 -- A simple optimization for the null case
6603 if Known_Null
(Ck_Node
) then
6608 -- For an N_Range Node, check for a null range and then if not
6609 -- null generate a range check action.
6611 if Nkind
(Ck_Node
) = N_Range
then
6613 -- There's no point in checking a range against itself
6615 if Ck_Node
= Scalar_Range
(T_Typ
) then
6620 T_LB
: constant Node_Id
:= Type_Low_Bound
(T_Typ
);
6621 T_HB
: constant Node_Id
:= Type_High_Bound
(T_Typ
);
6622 Known_T_LB
: constant Boolean := Compile_Time_Known_Value
(T_LB
);
6623 Known_T_HB
: constant Boolean := Compile_Time_Known_Value
(T_HB
);
6625 LB
: Node_Id
:= Low_Bound
(Ck_Node
);
6626 HB
: Node_Id
:= High_Bound
(Ck_Node
);
6630 Null_Range
: Boolean;
6631 Out_Of_Range_L
: Boolean;
6632 Out_Of_Range_H
: Boolean;
6635 -- Compute what is known at compile time
6637 if Known_T_LB
and Known_T_HB
then
6638 if Compile_Time_Known_Value
(LB
) then
6641 -- There's no point in checking that a bound is within its
6642 -- own range so pretend that it is known in this case. First
6643 -- deal with low bound.
6645 elsif Ekind
(Etype
(LB
)) = E_Signed_Integer_Subtype
6646 and then Scalar_Range
(Etype
(LB
)) = Scalar_Range
(T_Typ
)
6655 -- Likewise for the high bound
6657 if Compile_Time_Known_Value
(HB
) then
6660 elsif Ekind
(Etype
(HB
)) = E_Signed_Integer_Subtype
6661 and then Scalar_Range
(Etype
(HB
)) = Scalar_Range
(T_Typ
)
6671 -- Check for case where everything is static and we can do the
6672 -- check at compile time. This is skipped if we have an access
6673 -- type, since the access value may be null.
6675 -- ??? This code can be improved since you only need to know that
6676 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
6677 -- compile time to emit pertinent messages.
6679 if Known_T_LB
and Known_T_HB
and Known_LB
and Known_HB
6682 -- Floating-point case
6684 if Is_Floating_Point_Type
(S_Typ
) then
6685 Null_Range
:= Expr_Value_R
(HB
) < Expr_Value_R
(LB
);
6687 (Expr_Value_R
(LB
) < Expr_Value_R
(T_LB
))
6689 (Expr_Value_R
(LB
) > Expr_Value_R
(T_HB
));
6692 (Expr_Value_R
(HB
) > Expr_Value_R
(T_HB
))
6694 (Expr_Value_R
(HB
) < Expr_Value_R
(T_LB
));
6696 -- Fixed or discrete type case
6699 Null_Range
:= Expr_Value
(HB
) < Expr_Value
(LB
);
6701 (Expr_Value
(LB
) < Expr_Value
(T_LB
))
6703 (Expr_Value
(LB
) > Expr_Value
(T_HB
));
6706 (Expr_Value
(HB
) > Expr_Value
(T_HB
))
6708 (Expr_Value
(HB
) < Expr_Value
(T_LB
));
6711 if not Null_Range
then
6712 if Out_Of_Range_L
then
6713 if No
(Warn_Node
) then
6715 (Compile_Time_Constraint_Error
6716 (Low_Bound
(Ck_Node
),
6717 "static value out of range of}?", T_Typ
));
6721 (Compile_Time_Constraint_Error
6723 "static range out of bounds of}?", T_Typ
));
6727 if Out_Of_Range_H
then
6728 if No
(Warn_Node
) then
6730 (Compile_Time_Constraint_Error
6731 (High_Bound
(Ck_Node
),
6732 "static value out of range of}?", T_Typ
));
6736 (Compile_Time_Constraint_Error
6738 "static range out of bounds of}?", T_Typ
));
6745 LB
: Node_Id
:= Low_Bound
(Ck_Node
);
6746 HB
: Node_Id
:= High_Bound
(Ck_Node
);
6749 -- If either bound is a discriminant and we are within the
6750 -- record declaration, it is a use of the discriminant in a
6751 -- constraint of a component, and nothing can be checked
6752 -- here. The check will be emitted within the init proc.
6753 -- Before then, the discriminal has no real meaning.
6754 -- Similarly, if the entity is a discriminal, there is no
6755 -- check to perform yet.
6757 -- The same holds within a discriminated synchronized type,
6758 -- where the discriminant may constrain a component or an
6761 if Nkind
(LB
) = N_Identifier
6762 and then Denotes_Discriminant
(LB
, True)
6764 if Current_Scope
= Scope
(Entity
(LB
))
6765 or else Is_Concurrent_Type
(Current_Scope
)
6766 or else Ekind
(Entity
(LB
)) /= E_Discriminant
6771 New_Occurrence_Of
(Discriminal
(Entity
(LB
)), Loc
);
6775 if Nkind
(HB
) = N_Identifier
6776 and then Denotes_Discriminant
(HB
, True)
6778 if Current_Scope
= Scope
(Entity
(HB
))
6779 or else Is_Concurrent_Type
(Current_Scope
)
6780 or else Ekind
(Entity
(HB
)) /= E_Discriminant
6785 New_Occurrence_Of
(Discriminal
(Entity
(HB
)), Loc
);
6789 Cond
:= Discrete_Range_Cond
(Ck_Node
, T_Typ
);
6790 Set_Paren_Count
(Cond
, 1);
6796 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(HB
),
6797 Right_Opnd
=> Duplicate_Subexpr_No_Checks
(LB
)),
6798 Right_Opnd
=> Cond
);
6803 elsif Is_Scalar_Type
(S_Typ
) then
6805 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6806 -- except the above simply sets a flag in the node and lets
6807 -- gigi generate the check base on the Etype of the expression.
6808 -- Sometimes, however we want to do a dynamic check against an
6809 -- arbitrary target type, so we do that here.
6811 if Ekind
(Base_Type
(S_Typ
)) /= Ekind
(Base_Type
(T_Typ
)) then
6812 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
6814 -- For literals, we can tell if the constraint error will be
6815 -- raised at compile time, so we never need a dynamic check, but
6816 -- if the exception will be raised, then post the usual warning,
6817 -- and replace the literal with a raise constraint error
6818 -- expression. As usual, skip this for access types
6820 elsif Compile_Time_Known_Value
(Ck_Node
)
6821 and then not Do_Access
6824 LB
: constant Node_Id
:= Type_Low_Bound
(T_Typ
);
6825 UB
: constant Node_Id
:= Type_High_Bound
(T_Typ
);
6827 Out_Of_Range
: Boolean;
6828 Static_Bounds
: constant Boolean :=
6829 Compile_Time_Known_Value
(LB
)
6830 and Compile_Time_Known_Value
(UB
);
6833 -- Following range tests should use Sem_Eval routine ???
6835 if Static_Bounds
then
6836 if Is_Floating_Point_Type
(S_Typ
) then
6838 (Expr_Value_R
(Ck_Node
) < Expr_Value_R
(LB
))
6840 (Expr_Value_R
(Ck_Node
) > Expr_Value_R
(UB
));
6842 -- Fixed or discrete type
6846 Expr_Value
(Ck_Node
) < Expr_Value
(LB
)
6848 Expr_Value
(Ck_Node
) > Expr_Value
(UB
);
6851 -- Bounds of the type are static and the literal is out of
6852 -- range so output a warning message.
6854 if Out_Of_Range
then
6855 if No
(Warn_Node
) then
6857 (Compile_Time_Constraint_Error
6859 "static value out of range of}?", T_Typ
));
6863 (Compile_Time_Constraint_Error
6865 "static value out of range of}?", T_Typ
));
6870 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
6874 -- Here for the case of a non-static expression, we need a runtime
6875 -- check unless the source type range is guaranteed to be in the
6876 -- range of the target type.
6879 if not In_Subrange_Of
(S_Typ
, T_Typ
) then
6880 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
6885 if Is_Array_Type
(T_Typ
) and then Is_Array_Type
(S_Typ
) then
6886 if Is_Constrained
(T_Typ
) then
6888 Expr_Actual
:= Get_Referenced_Object
(Ck_Node
);
6889 Exptyp
:= Get_Actual_Subtype
(Expr_Actual
);
6891 if Is_Access_Type
(Exptyp
) then
6892 Exptyp
:= Designated_Type
(Exptyp
);
6895 -- String_Literal case. This needs to be handled specially be-
6896 -- cause no index types are available for string literals. The
6897 -- condition is simply:
6899 -- T_Typ'Length = string-literal-length
6901 if Nkind
(Expr_Actual
) = N_String_Literal
then
6904 -- General array case. Here we have a usable actual subtype for
6905 -- the expression, and the condition is built from the two types
6907 -- T_Typ'First < Exptyp'First or else
6908 -- T_Typ'Last > Exptyp'Last or else
6909 -- T_Typ'First(1) < Exptyp'First(1) or else
6910 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6913 elsif Is_Constrained
(Exptyp
) then
6915 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
6921 L_Index
:= First_Index
(T_Typ
);
6922 R_Index
:= First_Index
(Exptyp
);
6924 for Indx
in 1 .. Ndims
loop
6925 if not (Nkind
(L_Index
) = N_Raise_Constraint_Error
6927 Nkind
(R_Index
) = N_Raise_Constraint_Error
)
6929 -- Deal with compile time length check. Note that we
6930 -- skip this in the access case, because the access
6931 -- value may be null, so we cannot know statically.
6934 Subtypes_Statically_Match
6935 (Etype
(L_Index
), Etype
(R_Index
))
6937 -- If the target type is constrained then we
6938 -- have to check for exact equality of bounds
6939 -- (required for qualified expressions).
6941 if Is_Constrained
(T_Typ
) then
6944 Range_Equal_E_Cond
(Exptyp
, T_Typ
, Indx
));
6947 (Cond
, Range_E_Cond
(Exptyp
, T_Typ
, Indx
));
6957 -- Handle cases where we do not get a usable actual subtype that
6958 -- is constrained. This happens for example in the function call
6959 -- and explicit dereference cases. In these cases, we have to get
6960 -- the length or range from the expression itself, making sure we
6961 -- do not evaluate it more than once.
6963 -- Here Ck_Node is the original expression, or more properly the
6964 -- result of applying Duplicate_Expr to the original tree,
6965 -- forcing the result to be a name.
6969 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
6972 -- Build the condition for the explicit dereference case
6974 for Indx
in 1 .. Ndims
loop
6976 (Cond
, Range_N_Cond
(Ck_Node
, T_Typ
, Indx
));
6982 -- For a conversion to an unconstrained array type, generate an
6983 -- Action to check that the bounds of the source value are within
6984 -- the constraints imposed by the target type (RM 4.6(38)). No
6985 -- check is needed for a conversion to an access to unconstrained
6986 -- array type, as 4.6(24.15/2) requires the designated subtypes
6987 -- of the two access types to statically match.
6989 if Nkind
(Parent
(Ck_Node
)) = N_Type_Conversion
6990 and then not Do_Access
6993 Opnd_Index
: Node_Id
;
6994 Targ_Index
: Node_Id
;
6995 Opnd_Range
: Node_Id
;
6998 Opnd_Index
:= First_Index
(Get_Actual_Subtype
(Ck_Node
));
6999 Targ_Index
:= First_Index
(T_Typ
);
7000 while Present
(Opnd_Index
) loop
7002 -- If the index is a range, use its bounds. If it is an
7003 -- entity (as will be the case if it is a named subtype
7004 -- or an itype created for a slice) retrieve its range.
7006 if Is_Entity_Name
(Opnd_Index
)
7007 and then Is_Type
(Entity
(Opnd_Index
))
7009 Opnd_Range
:= Scalar_Range
(Entity
(Opnd_Index
));
7011 Opnd_Range
:= Opnd_Index
;
7014 if Nkind
(Opnd_Range
) = N_Range
then
7016 (Low_Bound
(Opnd_Range
), Etype
(Targ_Index
),
7017 Assume_Valid
=> True)
7020 (High_Bound
(Opnd_Range
), Etype
(Targ_Index
),
7021 Assume_Valid
=> True)
7025 -- If null range, no check needed
7028 Compile_Time_Known_Value
(High_Bound
(Opnd_Range
))
7030 Compile_Time_Known_Value
(Low_Bound
(Opnd_Range
))
7032 Expr_Value
(High_Bound
(Opnd_Range
)) <
7033 Expr_Value
(Low_Bound
(Opnd_Range
))
7037 elsif Is_Out_Of_Range
7038 (Low_Bound
(Opnd_Range
), Etype
(Targ_Index
),
7039 Assume_Valid
=> True)
7042 (High_Bound
(Opnd_Range
), Etype
(Targ_Index
),
7043 Assume_Valid
=> True)
7046 (Compile_Time_Constraint_Error
7047 (Wnode
, "value out of range of}?", T_Typ
));
7053 (Opnd_Range
, Etype
(Targ_Index
)));
7057 Next_Index
(Opnd_Index
);
7058 Next_Index
(Targ_Index
);
7065 -- Construct the test and insert into the tree
7067 if Present
(Cond
) then
7069 Cond
:= Guard_Access
(Cond
, Loc
, Ck_Node
);
7073 (Make_Raise_Constraint_Error
(Loc
,
7075 Reason
=> CE_Range_Check_Failed
));
7079 end Selected_Range_Checks
;
7081 -------------------------------
7082 -- Storage_Checks_Suppressed --
7083 -------------------------------
7085 function Storage_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
7087 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
7088 return Is_Check_Suppressed
(E
, Storage_Check
);
7090 return Scope_Suppress
(Storage_Check
);
7092 end Storage_Checks_Suppressed
;
7094 ---------------------------
7095 -- Tag_Checks_Suppressed --
7096 ---------------------------
7098 function Tag_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
7101 if Kill_Tag_Checks
(E
) then
7103 elsif Checks_May_Be_Suppressed
(E
) then
7104 return Is_Check_Suppressed
(E
, Tag_Check
);
7108 return Scope_Suppress
(Tag_Check
);
7109 end Tag_Checks_Suppressed
;
7111 --------------------------
7112 -- Validity_Check_Range --
7113 --------------------------
7115 procedure Validity_Check_Range
(N
: Node_Id
) is
7117 if Validity_Checks_On
and Validity_Check_Operands
then
7118 if Nkind
(N
) = N_Range
then
7119 Ensure_Valid
(Low_Bound
(N
));
7120 Ensure_Valid
(High_Bound
(N
));
7123 end Validity_Check_Range
;
7125 --------------------------------
7126 -- Validity_Checks_Suppressed --
7127 --------------------------------
7129 function Validity_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
7131 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
7132 return Is_Check_Suppressed
(E
, Validity_Check
);
7134 return Scope_Suppress
(Validity_Check
);
7136 end Validity_Checks_Suppressed
;