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 principally 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 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. Strictly we don't
654 -- have to do anything, since if the alignment is bad, we have an
655 -- erroneous program. However we are allowed to check for erroneous
656 -- conditions and we decide to do this by default if the check is not
659 -- However, don't do the check if elaboration code is unwanted
661 if Restriction_Active
(No_Elaboration_Code
) then
664 -- Generate a check to raise PE if alignment may be inappropriate
667 -- If the original expression is a non-static constant, use the
668 -- name of the constant itself rather than duplicating its
669 -- defining expression, which was extracted above.
671 -- Note: Expr is empty if the address-clause is applied to in-mode
672 -- actuals (allowed by 13.1(22)).
674 if not Present
(Expr
)
676 (Is_Entity_Name
(Expression
(AC
))
677 and then Ekind
(Entity
(Expression
(AC
))) = E_Constant
678 and then Nkind
(Parent
(Entity
(Expression
(AC
))))
679 = N_Object_Declaration
)
681 Expr
:= New_Copy_Tree
(Expression
(AC
));
683 Remove_Side_Effects
(Expr
);
686 Insert_After_And_Analyze
(N
,
687 Make_Raise_Program_Error
(Loc
,
694 (RTE
(RE_Integer_Address
), Expr
),
696 Make_Attribute_Reference
(Loc
,
697 Prefix
=> New_Occurrence_Of
(E
, Loc
),
698 Attribute_Name
=> Name_Alignment
)),
699 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
700 Reason
=> PE_Misaligned_Address_Value
),
701 Suppress
=> All_Checks
);
706 -- If we have some missing run time component in configurable run time
707 -- mode then just skip the check (it is not required in any case).
709 when RE_Not_Available
=>
711 end Apply_Address_Clause_Check
;
713 -------------------------------------
714 -- Apply_Arithmetic_Overflow_Check --
715 -------------------------------------
717 -- This routine is called only if the type is an integer type, and a
718 -- software arithmetic overflow check may be needed for op (add, subtract,
719 -- or multiply). This check is performed only if Software_Overflow_Checking
720 -- is enabled and Do_Overflow_Check is set. In this case we expand the
721 -- operation into a more complex sequence of tests that ensures that
722 -- overflow is properly caught.
724 procedure Apply_Arithmetic_Overflow_Check
(N
: Node_Id
) is
725 Loc
: constant Source_Ptr
:= Sloc
(N
);
726 Typ
: constant Entity_Id
:= Etype
(N
);
727 Rtyp
: constant Entity_Id
:= Root_Type
(Typ
);
730 -- An interesting special case. If the arithmetic operation appears as
731 -- the operand of a type conversion:
735 -- and all the following conditions apply:
737 -- arithmetic operation is for a signed integer type
738 -- target type type1 is a static integer subtype
739 -- range of x and y are both included in the range of type1
740 -- range of x op y is included in the range of type1
741 -- size of type1 is at least twice the result size of op
743 -- then we don't do an overflow check in any case, instead we transform
744 -- the operation so that we end up with:
746 -- type1 (type1 (x) op type1 (y))
748 -- This avoids intermediate overflow before the conversion. It is
749 -- explicitly permitted by RM 3.5.4(24):
751 -- For the execution of a predefined operation of a signed integer
752 -- type, the implementation need not raise Constraint_Error if the
753 -- result is outside the base range of the type, so long as the
754 -- correct result is produced.
756 -- It's hard to imagine that any programmer counts on the exception
757 -- being raised in this case, and in any case it's wrong coding to
758 -- have this expectation, given the RM permission. Furthermore, other
759 -- Ada compilers do allow such out of range results.
761 -- Note that we do this transformation even if overflow checking is
762 -- off, since this is precisely about giving the "right" result and
763 -- avoiding the need for an overflow check.
765 -- Note: this circuit is partially redundant with respect to the similar
766 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
767 -- with cases that do not come through here. We still need the following
768 -- processing even with the Exp_Ch4 code in place, since we want to be
769 -- sure not to generate the arithmetic overflow check in these cases
770 -- (Exp_Ch4 would have a hard time removing them once generated).
772 if Is_Signed_Integer_Type
(Typ
)
773 and then Nkind
(Parent
(N
)) = N_Type_Conversion
776 Target_Type
: constant Entity_Id
:=
777 Base_Type
(Entity
(Subtype_Mark
(Parent
(N
))));
791 if Is_Integer_Type
(Target_Type
)
792 and then RM_Size
(Root_Type
(Target_Type
)) >= 2 * RM_Size
(Rtyp
)
794 Tlo
:= Expr_Value
(Type_Low_Bound
(Target_Type
));
795 Thi
:= Expr_Value
(Type_High_Bound
(Target_Type
));
798 (Left_Opnd
(N
), LOK
, Llo
, Lhi
, Assume_Valid
=> True);
800 (Right_Opnd
(N
), ROK
, Rlo
, Rhi
, Assume_Valid
=> True);
803 and then Tlo
<= Llo
and then Lhi
<= Thi
804 and then Tlo
<= Rlo
and then Rhi
<= Thi
806 Determine_Range
(N
, VOK
, Vlo
, Vhi
, Assume_Valid
=> True);
808 if VOK
and then Tlo
<= Vlo
and then Vhi
<= Thi
then
809 Rewrite
(Left_Opnd
(N
),
810 Make_Type_Conversion
(Loc
,
811 Subtype_Mark
=> New_Occurrence_Of
(Target_Type
, Loc
),
812 Expression
=> Relocate_Node
(Left_Opnd
(N
))));
814 Rewrite
(Right_Opnd
(N
),
815 Make_Type_Conversion
(Loc
,
816 Subtype_Mark
=> New_Occurrence_Of
(Target_Type
, Loc
),
817 Expression
=> Relocate_Node
(Right_Opnd
(N
))));
819 -- Rewrite the conversion operand so that the original
820 -- node is retained, in order to avoid the warning for
821 -- redundant conversions in Resolve_Type_Conversion.
823 Rewrite
(N
, Relocate_Node
(N
));
825 Set_Etype
(N
, Target_Type
);
827 Analyze_And_Resolve
(Left_Opnd
(N
), Target_Type
);
828 Analyze_And_Resolve
(Right_Opnd
(N
), Target_Type
);
830 -- Given that the target type is twice the size of the
831 -- source type, overflow is now impossible, so we can
832 -- safely kill the overflow check and return.
834 Set_Do_Overflow_Check
(N
, False);
842 -- Now see if an overflow check is required
845 Siz
: constant Int
:= UI_To_Int
(Esize
(Rtyp
));
846 Dsiz
: constant Int
:= Siz
* 2;
853 -- Skip check if back end does overflow checks, or the overflow flag
854 -- is not set anyway, or we are not doing code expansion, or the
855 -- parent node is a type conversion whose operand is an arithmetic
856 -- operation on signed integers on which the expander can promote
857 -- later the operands to type Integer (see Expand_N_Type_Conversion).
859 -- Special case CLI target, where arithmetic overflow checks can be
860 -- performed for integer and long_integer
862 if Backend_Overflow_Checks_On_Target
863 or else not Do_Overflow_Check
(N
)
864 or else not Expander_Active
865 or else (Present
(Parent
(N
))
866 and then Nkind
(Parent
(N
)) = N_Type_Conversion
867 and then Integer_Promotion_Possible
(Parent
(N
)))
869 (VM_Target
= CLI_Target
and then Siz
>= Standard_Integer_Size
)
874 -- Otherwise, generate the full general code for front end overflow
875 -- detection, which works by doing arithmetic in a larger type:
881 -- Typ (Checktyp (x) op Checktyp (y));
883 -- where Typ is the type of the original expression, and Checktyp is
884 -- an integer type of sufficient length to hold the largest possible
887 -- If the size of check type exceeds the size of Long_Long_Integer,
888 -- we use a different approach, expanding to:
890 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
892 -- where xxx is Add, Multiply or Subtract as appropriate
894 -- Find check type if one exists
896 if Dsiz
<= Standard_Integer_Size
then
897 Ctyp
:= Standard_Integer
;
899 elsif Dsiz
<= Standard_Long_Long_Integer_Size
then
900 Ctyp
:= Standard_Long_Long_Integer
;
902 -- No check type exists, use runtime call
905 if Nkind
(N
) = N_Op_Add
then
906 Cent
:= RE_Add_With_Ovflo_Check
;
908 elsif Nkind
(N
) = N_Op_Multiply
then
909 Cent
:= RE_Multiply_With_Ovflo_Check
;
912 pragma Assert
(Nkind
(N
) = N_Op_Subtract
);
913 Cent
:= RE_Subtract_With_Ovflo_Check
;
918 Make_Function_Call
(Loc
,
919 Name
=> New_Reference_To
(RTE
(Cent
), Loc
),
920 Parameter_Associations
=> New_List
(
921 OK_Convert_To
(RTE
(RE_Integer_64
), Left_Opnd
(N
)),
922 OK_Convert_To
(RTE
(RE_Integer_64
), Right_Opnd
(N
))))));
924 Analyze_And_Resolve
(N
, Typ
);
928 -- If we fall through, we have the case where we do the arithmetic
929 -- in the next higher type and get the check by conversion. In these
930 -- cases Ctyp is set to the type to be used as the check type.
932 Opnod
:= Relocate_Node
(N
);
934 Opnd
:= OK_Convert_To
(Ctyp
, Left_Opnd
(Opnod
));
937 Set_Etype
(Opnd
, Ctyp
);
938 Set_Analyzed
(Opnd
, True);
939 Set_Left_Opnd
(Opnod
, Opnd
);
941 Opnd
:= OK_Convert_To
(Ctyp
, Right_Opnd
(Opnod
));
944 Set_Etype
(Opnd
, Ctyp
);
945 Set_Analyzed
(Opnd
, True);
946 Set_Right_Opnd
(Opnod
, Opnd
);
948 -- The type of the operation changes to the base type of the check
949 -- type, and we reset the overflow check indication, since clearly no
950 -- overflow is possible now that we are using a double length type.
951 -- We also set the Analyzed flag to avoid a recursive attempt to
954 Set_Etype
(Opnod
, Base_Type
(Ctyp
));
955 Set_Do_Overflow_Check
(Opnod
, False);
956 Set_Analyzed
(Opnod
, True);
958 -- Now build the outer conversion
960 Opnd
:= OK_Convert_To
(Typ
, Opnod
);
962 Set_Etype
(Opnd
, Typ
);
964 -- In the discrete type case, we directly generate the range check
965 -- for the outer operand. This range check will implement the
966 -- required overflow check.
968 if Is_Discrete_Type
(Typ
) then
971 (Expression
(N
), Typ
, CE_Overflow_Check_Failed
);
973 -- For other types, we enable overflow checking on the conversion,
974 -- after setting the node as analyzed to prevent recursive attempts
975 -- to expand the conversion node.
978 Set_Analyzed
(Opnd
, True);
979 Enable_Overflow_Check
(Opnd
);
984 when RE_Not_Available
=>
987 end Apply_Arithmetic_Overflow_Check
;
989 ----------------------------
990 -- Apply_Constraint_Check --
991 ----------------------------
993 procedure Apply_Constraint_Check
996 No_Sliding
: Boolean := False)
998 Desig_Typ
: Entity_Id
;
1001 -- No checks inside a generic (check the instantiations)
1003 if Inside_A_Generic
then
1007 -- Apply required constraint checks
1009 if Is_Scalar_Type
(Typ
) then
1010 Apply_Scalar_Range_Check
(N
, Typ
);
1012 elsif Is_Array_Type
(Typ
) then
1014 -- A useful optimization: an aggregate with only an others clause
1015 -- always has the right bounds.
1017 if Nkind
(N
) = N_Aggregate
1018 and then No
(Expressions
(N
))
1020 (First
(Choices
(First
(Component_Associations
(N
)))))
1026 if Is_Constrained
(Typ
) then
1027 Apply_Length_Check
(N
, Typ
);
1030 Apply_Range_Check
(N
, Typ
);
1033 Apply_Range_Check
(N
, Typ
);
1036 elsif (Is_Record_Type
(Typ
)
1037 or else Is_Private_Type
(Typ
))
1038 and then Has_Discriminants
(Base_Type
(Typ
))
1039 and then Is_Constrained
(Typ
)
1041 Apply_Discriminant_Check
(N
, Typ
);
1043 elsif Is_Access_Type
(Typ
) then
1045 Desig_Typ
:= Designated_Type
(Typ
);
1047 -- No checks necessary if expression statically null
1049 if Known_Null
(N
) then
1050 if Can_Never_Be_Null
(Typ
) then
1051 Install_Null_Excluding_Check
(N
);
1054 -- No sliding possible on access to arrays
1056 elsif Is_Array_Type
(Desig_Typ
) then
1057 if Is_Constrained
(Desig_Typ
) then
1058 Apply_Length_Check
(N
, Typ
);
1061 Apply_Range_Check
(N
, Typ
);
1063 elsif Has_Discriminants
(Base_Type
(Desig_Typ
))
1064 and then Is_Constrained
(Desig_Typ
)
1066 Apply_Discriminant_Check
(N
, Typ
);
1069 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1070 -- this check if the constraint node is illegal, as shown by having
1071 -- an error posted. This additional guard prevents cascaded errors
1072 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1074 if Can_Never_Be_Null
(Typ
)
1075 and then not Can_Never_Be_Null
(Etype
(N
))
1076 and then not Error_Posted
(N
)
1078 Install_Null_Excluding_Check
(N
);
1081 end Apply_Constraint_Check
;
1083 ------------------------------
1084 -- Apply_Discriminant_Check --
1085 ------------------------------
1087 procedure Apply_Discriminant_Check
1090 Lhs
: Node_Id
:= Empty
)
1092 Loc
: constant Source_Ptr
:= Sloc
(N
);
1093 Do_Access
: constant Boolean := Is_Access_Type
(Typ
);
1094 S_Typ
: Entity_Id
:= Etype
(N
);
1098 function Denotes_Explicit_Dereference
(Obj
: Node_Id
) return Boolean;
1099 -- A heap object with an indefinite subtype is constrained by its
1100 -- initial value, and assigning to it requires a constraint_check.
1101 -- The target may be an explicit dereference, or a renaming of one.
1103 function Is_Aliased_Unconstrained_Component
return Boolean;
1104 -- It is possible for an aliased component to have a nominal
1105 -- unconstrained subtype (through instantiation). If this is a
1106 -- discriminated component assigned in the expansion of an aggregate
1107 -- in an initialization, the check must be suppressed. This unusual
1108 -- situation requires a predicate of its own.
1110 ----------------------------------
1111 -- Denotes_Explicit_Dereference --
1112 ----------------------------------
1114 function Denotes_Explicit_Dereference
(Obj
: Node_Id
) return Boolean is
1117 Nkind
(Obj
) = N_Explicit_Dereference
1119 (Is_Entity_Name
(Obj
)
1120 and then Present
(Renamed_Object
(Entity
(Obj
)))
1121 and then Nkind
(Renamed_Object
(Entity
(Obj
))) =
1122 N_Explicit_Dereference
);
1123 end Denotes_Explicit_Dereference
;
1125 ----------------------------------------
1126 -- Is_Aliased_Unconstrained_Component --
1127 ----------------------------------------
1129 function Is_Aliased_Unconstrained_Component
return Boolean is
1134 if Nkind
(Lhs
) /= N_Selected_Component
then
1137 Comp
:= Entity
(Selector_Name
(Lhs
));
1138 Pref
:= Prefix
(Lhs
);
1141 if Ekind
(Comp
) /= E_Component
1142 or else not Is_Aliased
(Comp
)
1147 return not Comes_From_Source
(Pref
)
1148 and then In_Instance
1149 and then not Is_Constrained
(Etype
(Comp
));
1150 end Is_Aliased_Unconstrained_Component
;
1152 -- Start of processing for Apply_Discriminant_Check
1156 T_Typ
:= Designated_Type
(Typ
);
1161 -- Nothing to do if discriminant checks are suppressed or else no code
1162 -- is to be generated
1164 if not Expander_Active
1165 or else Discriminant_Checks_Suppressed
(T_Typ
)
1170 -- No discriminant checks necessary for an access when expression is
1171 -- statically Null. This is not only an optimization, it is fundamental
1172 -- because otherwise discriminant checks may be generated in init procs
1173 -- for types containing an access to a not-yet-frozen record, causing a
1174 -- deadly forward reference.
1176 -- Also, if the expression is of an access type whose designated type is
1177 -- incomplete, then the access value must be null and we suppress the
1180 if Known_Null
(N
) then
1183 elsif Is_Access_Type
(S_Typ
) then
1184 S_Typ
:= Designated_Type
(S_Typ
);
1186 if Ekind
(S_Typ
) = E_Incomplete_Type
then
1191 -- If an assignment target is present, then we need to generate the
1192 -- actual subtype if the target is a parameter or aliased object with
1193 -- an unconstrained nominal subtype.
1195 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1196 -- subtype to the parameter and dereference cases, since other aliased
1197 -- objects are unconstrained (unless the nominal subtype is explicitly
1201 and then (Present
(Param_Entity
(Lhs
))
1202 or else (Ada_Version
< Ada_2005
1203 and then not Is_Constrained
(T_Typ
)
1204 and then Is_Aliased_View
(Lhs
)
1205 and then not Is_Aliased_Unconstrained_Component
)
1206 or else (Ada_Version
>= Ada_2005
1207 and then not Is_Constrained
(T_Typ
)
1208 and then Denotes_Explicit_Dereference
(Lhs
)
1209 and then Nkind
(Original_Node
(Lhs
)) /=
1212 T_Typ
:= Get_Actual_Subtype
(Lhs
);
1215 -- Nothing to do if the type is unconstrained (this is the case where
1216 -- the actual subtype in the RM sense of N is unconstrained and no check
1219 if not Is_Constrained
(T_Typ
) then
1222 -- Ada 2005: nothing to do if the type is one for which there is a
1223 -- partial view that is constrained.
1225 elsif Ada_Version
>= Ada_2005
1226 and then Has_Constrained_Partial_View
(Base_Type
(T_Typ
))
1231 -- Nothing to do if the type is an Unchecked_Union
1233 if Is_Unchecked_Union
(Base_Type
(T_Typ
)) then
1237 -- Suppress checks if the subtypes are the same. the check must be
1238 -- preserved in an assignment to a formal, because the constraint is
1239 -- given by the actual.
1241 if Nkind
(Original_Node
(N
)) /= N_Allocator
1243 or else not Is_Entity_Name
(Lhs
)
1244 or else No
(Param_Entity
(Lhs
)))
1247 or else (Do_Access
and then Designated_Type
(Typ
) = S_Typ
))
1248 and then not Is_Aliased_View
(Lhs
)
1253 -- We can also eliminate checks on allocators with a subtype mark that
1254 -- coincides with the context type. The context type may be a subtype
1255 -- without a constraint (common case, a generic actual).
1257 elsif Nkind
(Original_Node
(N
)) = N_Allocator
1258 and then Is_Entity_Name
(Expression
(Original_Node
(N
)))
1261 Alloc_Typ
: constant Entity_Id
:=
1262 Entity
(Expression
(Original_Node
(N
)));
1265 if Alloc_Typ
= T_Typ
1266 or else (Nkind
(Parent
(T_Typ
)) = N_Subtype_Declaration
1267 and then Is_Entity_Name
(
1268 Subtype_Indication
(Parent
(T_Typ
)))
1269 and then Alloc_Typ
= Base_Type
(T_Typ
))
1277 -- See if we have a case where the types are both constrained, and all
1278 -- the constraints are constants. In this case, we can do the check
1279 -- successfully at compile time.
1281 -- We skip this check for the case where the node is a rewritten`
1282 -- allocator, because it already carries the context subtype, and
1283 -- extracting the discriminants from the aggregate is messy.
1285 if Is_Constrained
(S_Typ
)
1286 and then Nkind
(Original_Node
(N
)) /= N_Allocator
1296 -- S_Typ may not have discriminants in the case where it is a
1297 -- private type completed by a default discriminated type. In that
1298 -- case, we need to get the constraints from the underlying_type.
1299 -- If the underlying type is unconstrained (i.e. has no default
1300 -- discriminants) no check is needed.
1302 if Has_Discriminants
(S_Typ
) then
1303 Discr
:= First_Discriminant
(S_Typ
);
1304 DconS
:= First_Elmt
(Discriminant_Constraint
(S_Typ
));
1307 Discr
:= First_Discriminant
(Underlying_Type
(S_Typ
));
1310 (Discriminant_Constraint
(Underlying_Type
(S_Typ
)));
1316 -- A further optimization: if T_Typ is derived from S_Typ
1317 -- without imposing a constraint, no check is needed.
1319 if Nkind
(Original_Node
(Parent
(T_Typ
))) =
1320 N_Full_Type_Declaration
1323 Type_Def
: constant Node_Id
:=
1325 (Original_Node
(Parent
(T_Typ
)));
1327 if Nkind
(Type_Def
) = N_Derived_Type_Definition
1328 and then Is_Entity_Name
(Subtype_Indication
(Type_Def
))
1329 and then Entity
(Subtype_Indication
(Type_Def
)) = S_Typ
1337 DconT
:= First_Elmt
(Discriminant_Constraint
(T_Typ
));
1339 while Present
(Discr
) loop
1340 ItemS
:= Node
(DconS
);
1341 ItemT
:= Node
(DconT
);
1343 -- For a discriminated component type constrained by the
1344 -- current instance of an enclosing type, there is no
1345 -- applicable discriminant check.
1347 if Nkind
(ItemT
) = N_Attribute_Reference
1348 and then Is_Access_Type
(Etype
(ItemT
))
1349 and then Is_Entity_Name
(Prefix
(ItemT
))
1350 and then Is_Type
(Entity
(Prefix
(ItemT
)))
1355 -- If the expressions for the discriminants are identical
1356 -- and it is side-effect free (for now just an entity),
1357 -- this may be a shared constraint, e.g. from a subtype
1358 -- without a constraint introduced as a generic actual.
1359 -- Examine other discriminants if any.
1362 and then Is_Entity_Name
(ItemS
)
1366 elsif not Is_OK_Static_Expression
(ItemS
)
1367 or else not Is_OK_Static_Expression
(ItemT
)
1371 elsif Expr_Value
(ItemS
) /= Expr_Value
(ItemT
) then
1372 if Do_Access
then -- needs run-time check.
1375 Apply_Compile_Time_Constraint_Error
1376 (N
, "incorrect value for discriminant&?",
1377 CE_Discriminant_Check_Failed
, Ent
=> Discr
);
1384 Next_Discriminant
(Discr
);
1393 -- Here we need a discriminant check. First build the expression
1394 -- for the comparisons of the discriminants:
1396 -- (n.disc1 /= typ.disc1) or else
1397 -- (n.disc2 /= typ.disc2) or else
1399 -- (n.discn /= typ.discn)
1401 Cond
:= Build_Discriminant_Checks
(N
, T_Typ
);
1403 -- If Lhs is set and is a parameter, then the condition is
1404 -- guarded by: lhs'constrained and then (condition built above)
1406 if Present
(Param_Entity
(Lhs
)) then
1410 Make_Attribute_Reference
(Loc
,
1411 Prefix
=> New_Occurrence_Of
(Param_Entity
(Lhs
), Loc
),
1412 Attribute_Name
=> Name_Constrained
),
1413 Right_Opnd
=> Cond
);
1417 Cond
:= Guard_Access
(Cond
, Loc
, N
);
1421 Make_Raise_Constraint_Error
(Loc
,
1423 Reason
=> CE_Discriminant_Check_Failed
));
1424 end Apply_Discriminant_Check
;
1426 ------------------------
1427 -- Apply_Divide_Check --
1428 ------------------------
1430 procedure Apply_Divide_Check
(N
: Node_Id
) is
1431 Loc
: constant Source_Ptr
:= Sloc
(N
);
1432 Typ
: constant Entity_Id
:= Etype
(N
);
1433 Left
: constant Node_Id
:= Left_Opnd
(N
);
1434 Right
: constant Node_Id
:= Right_Opnd
(N
);
1444 pragma Warnings
(Off
, Lhi
);
1445 -- Don't actually use this value
1449 and then not Backend_Divide_Checks_On_Target
1450 and then Check_Needed
(Right
, Division_Check
)
1452 Determine_Range
(Right
, ROK
, Rlo
, Rhi
, Assume_Valid
=> True);
1454 -- See if division by zero possible, and if so generate test. This
1455 -- part of the test is not controlled by the -gnato switch.
1457 if Do_Division_Check
(N
) then
1458 if (not ROK
) or else (Rlo
<= 0 and then 0 <= Rhi
) then
1460 Make_Raise_Constraint_Error
(Loc
,
1463 Left_Opnd
=> Duplicate_Subexpr_Move_Checks
(Right
),
1464 Right_Opnd
=> Make_Integer_Literal
(Loc
, 0)),
1465 Reason
=> CE_Divide_By_Zero
));
1469 -- Test for extremely annoying case of xxx'First divided by -1
1471 if Do_Overflow_Check
(N
) then
1472 if Nkind
(N
) = N_Op_Divide
1473 and then Is_Signed_Integer_Type
(Typ
)
1475 Determine_Range
(Left
, LOK
, Llo
, Lhi
, Assume_Valid
=> True);
1476 LLB
:= Expr_Value
(Type_Low_Bound
(Base_Type
(Typ
)));
1478 if ((not ROK
) or else (Rlo
<= (-1) and then (-1) <= Rhi
))
1480 ((not LOK
) or else (Llo
= LLB
))
1483 Make_Raise_Constraint_Error
(Loc
,
1489 Duplicate_Subexpr_Move_Checks
(Left
),
1490 Right_Opnd
=> Make_Integer_Literal
(Loc
, LLB
)),
1494 Duplicate_Subexpr
(Right
),
1496 Make_Integer_Literal
(Loc
, -1))),
1497 Reason
=> CE_Overflow_Check_Failed
));
1502 end Apply_Divide_Check
;
1504 ----------------------------------
1505 -- Apply_Float_Conversion_Check --
1506 ----------------------------------
1508 -- Let F and I be the source and target types of the conversion. The RM
1509 -- specifies that a floating-point value X is rounded to the nearest
1510 -- integer, with halfway cases being rounded away from zero. The rounded
1511 -- value of X is checked against I'Range.
1513 -- The catch in the above paragraph is that there is no good way to know
1514 -- whether the round-to-integer operation resulted in overflow. A remedy is
1515 -- to perform a range check in the floating-point domain instead, however:
1517 -- (1) The bounds may not be known at compile time
1518 -- (2) The check must take into account rounding or truncation.
1519 -- (3) The range of type I may not be exactly representable in F.
1520 -- (4) For the rounding case, The end-points I'First - 0.5 and
1521 -- I'Last + 0.5 may or may not be in range, depending on the
1522 -- sign of I'First and I'Last.
1523 -- (5) X may be a NaN, which will fail any comparison
1525 -- The following steps correctly convert X with rounding:
1527 -- (1) If either I'First or I'Last is not known at compile time, use
1528 -- I'Base instead of I in the next three steps and perform a
1529 -- regular range check against I'Range after conversion.
1530 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1531 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1532 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1533 -- In other words, take one of the closest floating-point numbers
1534 -- (which is an integer value) to I'First, and see if it is in
1536 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1537 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1538 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1539 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1540 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1542 -- For the truncating case, replace steps (2) and (3) as follows:
1543 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1544 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1546 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1547 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1550 procedure Apply_Float_Conversion_Check
1552 Target_Typ
: Entity_Id
)
1554 LB
: constant Node_Id
:= Type_Low_Bound
(Target_Typ
);
1555 HB
: constant Node_Id
:= Type_High_Bound
(Target_Typ
);
1556 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
1557 Expr_Type
: constant Entity_Id
:= Base_Type
(Etype
(Ck_Node
));
1558 Target_Base
: constant Entity_Id
:=
1559 Implementation_Base_Type
(Target_Typ
);
1561 Par
: constant Node_Id
:= Parent
(Ck_Node
);
1562 pragma Assert
(Nkind
(Par
) = N_Type_Conversion
);
1563 -- Parent of check node, must be a type conversion
1565 Truncate
: constant Boolean := Float_Truncate
(Par
);
1566 Max_Bound
: constant Uint
:=
1568 (Machine_Radix_Value
(Expr_Type
),
1569 Machine_Mantissa_Value
(Expr_Type
) - 1) - 1;
1571 -- Largest bound, so bound plus or minus half is a machine number of F
1573 Ifirst
, Ilast
: Uint
;
1574 -- Bounds of integer type
1577 -- Bounds to check in floating-point domain
1579 Lo_OK
, Hi_OK
: Boolean;
1580 -- True iff Lo resp. Hi belongs to I'Range
1582 Lo_Chk
, Hi_Chk
: Node_Id
;
1583 -- Expressions that are False iff check fails
1585 Reason
: RT_Exception_Code
;
1588 if not Compile_Time_Known_Value
(LB
)
1589 or not Compile_Time_Known_Value
(HB
)
1592 -- First check that the value falls in the range of the base type,
1593 -- to prevent overflow during conversion and then perform a
1594 -- regular range check against the (dynamic) bounds.
1596 pragma Assert
(Target_Base
/= Target_Typ
);
1598 Temp
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', Par
);
1601 Apply_Float_Conversion_Check
(Ck_Node
, Target_Base
);
1602 Set_Etype
(Temp
, Target_Base
);
1604 Insert_Action
(Parent
(Par
),
1605 Make_Object_Declaration
(Loc
,
1606 Defining_Identifier
=> Temp
,
1607 Object_Definition
=> New_Occurrence_Of
(Target_Typ
, Loc
),
1608 Expression
=> New_Copy_Tree
(Par
)),
1609 Suppress
=> All_Checks
);
1612 Make_Raise_Constraint_Error
(Loc
,
1615 Left_Opnd
=> New_Occurrence_Of
(Temp
, Loc
),
1616 Right_Opnd
=> New_Occurrence_Of
(Target_Typ
, Loc
)),
1617 Reason
=> CE_Range_Check_Failed
));
1618 Rewrite
(Par
, New_Occurrence_Of
(Temp
, Loc
));
1624 -- Get the (static) bounds of the target type
1626 Ifirst
:= Expr_Value
(LB
);
1627 Ilast
:= Expr_Value
(HB
);
1629 -- A simple optimization: if the expression is a universal literal,
1630 -- we can do the comparison with the bounds and the conversion to
1631 -- an integer type statically. The range checks are unchanged.
1633 if Nkind
(Ck_Node
) = N_Real_Literal
1634 and then Etype
(Ck_Node
) = Universal_Real
1635 and then Is_Integer_Type
(Target_Typ
)
1636 and then Nkind
(Parent
(Ck_Node
)) = N_Type_Conversion
1639 Int_Val
: constant Uint
:= UR_To_Uint
(Realval
(Ck_Node
));
1642 if Int_Val
<= Ilast
and then Int_Val
>= Ifirst
then
1644 -- Conversion is safe
1646 Rewrite
(Parent
(Ck_Node
),
1647 Make_Integer_Literal
(Loc
, UI_To_Int
(Int_Val
)));
1648 Analyze_And_Resolve
(Parent
(Ck_Node
), Target_Typ
);
1654 -- Check against lower bound
1656 if Truncate
and then Ifirst
> 0 then
1657 Lo
:= Pred
(Expr_Type
, UR_From_Uint
(Ifirst
));
1661 Lo
:= Succ
(Expr_Type
, UR_From_Uint
(Ifirst
- 1));
1664 elsif abs (Ifirst
) < Max_Bound
then
1665 Lo
:= UR_From_Uint
(Ifirst
) - Ureal_Half
;
1666 Lo_OK
:= (Ifirst
> 0);
1669 Lo
:= Machine
(Expr_Type
, UR_From_Uint
(Ifirst
), Round_Even
, Ck_Node
);
1670 Lo_OK
:= (Lo
>= UR_From_Uint
(Ifirst
));
1675 -- Lo_Chk := (X >= Lo)
1677 Lo_Chk
:= Make_Op_Ge
(Loc
,
1678 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
1679 Right_Opnd
=> Make_Real_Literal
(Loc
, Lo
));
1682 -- Lo_Chk := (X > Lo)
1684 Lo_Chk
:= Make_Op_Gt
(Loc
,
1685 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
1686 Right_Opnd
=> Make_Real_Literal
(Loc
, Lo
));
1689 -- Check against higher bound
1691 if Truncate
and then Ilast
< 0 then
1692 Hi
:= Succ
(Expr_Type
, UR_From_Uint
(Ilast
));
1696 Hi
:= Pred
(Expr_Type
, UR_From_Uint
(Ilast
+ 1));
1699 elsif abs (Ilast
) < Max_Bound
then
1700 Hi
:= UR_From_Uint
(Ilast
) + Ureal_Half
;
1701 Hi_OK
:= (Ilast
< 0);
1703 Hi
:= Machine
(Expr_Type
, UR_From_Uint
(Ilast
), Round_Even
, Ck_Node
);
1704 Hi_OK
:= (Hi
<= UR_From_Uint
(Ilast
));
1709 -- Hi_Chk := (X <= Hi)
1711 Hi_Chk
:= Make_Op_Le
(Loc
,
1712 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
1713 Right_Opnd
=> Make_Real_Literal
(Loc
, Hi
));
1716 -- Hi_Chk := (X < Hi)
1718 Hi_Chk
:= Make_Op_Lt
(Loc
,
1719 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
1720 Right_Opnd
=> Make_Real_Literal
(Loc
, Hi
));
1723 -- If the bounds of the target type are the same as those of the base
1724 -- type, the check is an overflow check as a range check is not
1725 -- performed in these cases.
1727 if Expr_Value
(Type_Low_Bound
(Target_Base
)) = Ifirst
1728 and then Expr_Value
(Type_High_Bound
(Target_Base
)) = Ilast
1730 Reason
:= CE_Overflow_Check_Failed
;
1732 Reason
:= CE_Range_Check_Failed
;
1735 -- Raise CE if either conditions does not hold
1737 Insert_Action
(Ck_Node
,
1738 Make_Raise_Constraint_Error
(Loc
,
1739 Condition
=> Make_Op_Not
(Loc
, Make_And_Then
(Loc
, Lo_Chk
, Hi_Chk
)),
1741 end Apply_Float_Conversion_Check
;
1743 ------------------------
1744 -- Apply_Length_Check --
1745 ------------------------
1747 procedure Apply_Length_Check
1749 Target_Typ
: Entity_Id
;
1750 Source_Typ
: Entity_Id
:= Empty
)
1753 Apply_Selected_Length_Checks
1754 (Ck_Node
, Target_Typ
, Source_Typ
, Do_Static
=> False);
1755 end Apply_Length_Check
;
1757 ---------------------------
1758 -- Apply_Predicate_Check --
1759 ---------------------------
1761 procedure Apply_Predicate_Check
(N
: Node_Id
; Typ
: Entity_Id
) is
1763 if Present
(Predicate_Function
(Typ
)) then
1765 Make_Predicate_Check
(Typ
, Duplicate_Subexpr
(N
)));
1767 end Apply_Predicate_Check
;
1769 -----------------------
1770 -- Apply_Range_Check --
1771 -----------------------
1773 procedure Apply_Range_Check
1775 Target_Typ
: Entity_Id
;
1776 Source_Typ
: Entity_Id
:= Empty
)
1779 Apply_Selected_Range_Checks
1780 (Ck_Node
, Target_Typ
, Source_Typ
, Do_Static
=> False);
1781 end Apply_Range_Check
;
1783 ------------------------------
1784 -- Apply_Scalar_Range_Check --
1785 ------------------------------
1787 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1788 -- off if it is already set on.
1790 procedure Apply_Scalar_Range_Check
1792 Target_Typ
: Entity_Id
;
1793 Source_Typ
: Entity_Id
:= Empty
;
1794 Fixed_Int
: Boolean := False)
1796 Parnt
: constant Node_Id
:= Parent
(Expr
);
1798 Arr
: Node_Id
:= Empty
; -- initialize to prevent warning
1799 Arr_Typ
: Entity_Id
:= Empty
; -- initialize to prevent warning
1802 Is_Subscr_Ref
: Boolean;
1803 -- Set true if Expr is a subscript
1805 Is_Unconstrained_Subscr_Ref
: Boolean;
1806 -- Set true if Expr is a subscript of an unconstrained array. In this
1807 -- case we do not attempt to do an analysis of the value against the
1808 -- range of the subscript, since we don't know the actual subtype.
1811 -- Set to True if Expr should be regarded as a real value even though
1812 -- the type of Expr might be discrete.
1814 procedure Bad_Value
;
1815 -- Procedure called if value is determined to be out of range
1821 procedure Bad_Value
is
1823 Apply_Compile_Time_Constraint_Error
1824 (Expr
, "value not in range of}?", CE_Range_Check_Failed
,
1829 -- Start of processing for Apply_Scalar_Range_Check
1832 -- Return if check obviously not needed
1835 -- Not needed inside generic
1839 -- Not needed if previous error
1841 or else Target_Typ
= Any_Type
1842 or else Nkind
(Expr
) = N_Error
1844 -- Not needed for non-scalar type
1846 or else not Is_Scalar_Type
(Target_Typ
)
1848 -- Not needed if we know node raises CE already
1850 or else Raises_Constraint_Error
(Expr
)
1855 -- Now, see if checks are suppressed
1858 Is_List_Member
(Expr
) and then Nkind
(Parnt
) = N_Indexed_Component
;
1860 if Is_Subscr_Ref
then
1861 Arr
:= Prefix
(Parnt
);
1862 Arr_Typ
:= Get_Actual_Subtype_If_Available
(Arr
);
1865 if not Do_Range_Check
(Expr
) then
1867 -- Subscript reference. Check for Index_Checks suppressed
1869 if Is_Subscr_Ref
then
1871 -- Check array type and its base type
1873 if Index_Checks_Suppressed
(Arr_Typ
)
1874 or else Index_Checks_Suppressed
(Base_Type
(Arr_Typ
))
1878 -- Check array itself if it is an entity name
1880 elsif Is_Entity_Name
(Arr
)
1881 and then Index_Checks_Suppressed
(Entity
(Arr
))
1885 -- Check expression itself if it is an entity name
1887 elsif Is_Entity_Name
(Expr
)
1888 and then Index_Checks_Suppressed
(Entity
(Expr
))
1893 -- All other cases, check for Range_Checks suppressed
1896 -- Check target type and its base type
1898 if Range_Checks_Suppressed
(Target_Typ
)
1899 or else Range_Checks_Suppressed
(Base_Type
(Target_Typ
))
1903 -- Check expression itself if it is an entity name
1905 elsif Is_Entity_Name
(Expr
)
1906 and then Range_Checks_Suppressed
(Entity
(Expr
))
1910 -- If Expr is part of an assignment statement, then check left
1911 -- side of assignment if it is an entity name.
1913 elsif Nkind
(Parnt
) = N_Assignment_Statement
1914 and then Is_Entity_Name
(Name
(Parnt
))
1915 and then Range_Checks_Suppressed
(Entity
(Name
(Parnt
)))
1922 -- Do not set range checks if they are killed
1924 if Nkind
(Expr
) = N_Unchecked_Type_Conversion
1925 and then Kill_Range_Check
(Expr
)
1930 -- Do not set range checks for any values from System.Scalar_Values
1931 -- since the whole idea of such values is to avoid checking them!
1933 if Is_Entity_Name
(Expr
)
1934 and then Is_RTU
(Scope
(Entity
(Expr
)), System_Scalar_Values
)
1939 -- Now see if we need a check
1941 if No
(Source_Typ
) then
1942 S_Typ
:= Etype
(Expr
);
1944 S_Typ
:= Source_Typ
;
1947 if not Is_Scalar_Type
(S_Typ
) or else S_Typ
= Any_Type
then
1951 Is_Unconstrained_Subscr_Ref
:=
1952 Is_Subscr_Ref
and then not Is_Constrained
(Arr_Typ
);
1954 -- Always do a range check if the source type includes infinities and
1955 -- the target type does not include infinities. We do not do this if
1956 -- range checks are killed.
1958 if Is_Floating_Point_Type
(S_Typ
)
1959 and then Has_Infinities
(S_Typ
)
1960 and then not Has_Infinities
(Target_Typ
)
1962 Enable_Range_Check
(Expr
);
1965 -- Return if we know expression is definitely in the range of the target
1966 -- type as determined by Determine_Range. Right now we only do this for
1967 -- discrete types, and not fixed-point or floating-point types.
1969 -- The additional less-precise tests below catch these cases
1971 -- Note: skip this if we are given a source_typ, since the point of
1972 -- supplying a Source_Typ is to stop us looking at the expression.
1973 -- We could sharpen this test to be out parameters only ???
1975 if Is_Discrete_Type
(Target_Typ
)
1976 and then Is_Discrete_Type
(Etype
(Expr
))
1977 and then not Is_Unconstrained_Subscr_Ref
1978 and then No
(Source_Typ
)
1981 Tlo
: constant Node_Id
:= Type_Low_Bound
(Target_Typ
);
1982 Thi
: constant Node_Id
:= Type_High_Bound
(Target_Typ
);
1987 if Compile_Time_Known_Value
(Tlo
)
1988 and then Compile_Time_Known_Value
(Thi
)
1991 Lov
: constant Uint
:= Expr_Value
(Tlo
);
1992 Hiv
: constant Uint
:= Expr_Value
(Thi
);
1995 -- If range is null, we for sure have a constraint error
1996 -- (we don't even need to look at the value involved,
1997 -- since all possible values will raise CE).
2004 -- Otherwise determine range of value
2006 Determine_Range
(Expr
, OK
, Lo
, Hi
, Assume_Valid
=> True);
2010 -- If definitely in range, all OK
2012 if Lo
>= Lov
and then Hi
<= Hiv
then
2015 -- If definitely not in range, warn
2017 elsif Lov
> Hi
or else Hiv
< Lo
then
2021 -- Otherwise we don't know
2033 Is_Floating_Point_Type
(S_Typ
)
2034 or else (Is_Fixed_Point_Type
(S_Typ
) and then not Fixed_Int
);
2036 -- Check if we can determine at compile time whether Expr is in the
2037 -- range of the target type. Note that if S_Typ is within the bounds
2038 -- of Target_Typ then this must be the case. This check is meaningful
2039 -- only if this is not a conversion between integer and real types.
2041 if not Is_Unconstrained_Subscr_Ref
2043 Is_Discrete_Type
(S_Typ
) = Is_Discrete_Type
(Target_Typ
)
2045 (In_Subrange_Of
(S_Typ
, Target_Typ
, Fixed_Int
)
2047 Is_In_Range
(Expr
, Target_Typ
,
2048 Assume_Valid
=> True,
2049 Fixed_Int
=> Fixed_Int
,
2050 Int_Real
=> Int_Real
))
2054 elsif Is_Out_Of_Range
(Expr
, Target_Typ
,
2055 Assume_Valid
=> True,
2056 Fixed_Int
=> Fixed_Int
,
2057 Int_Real
=> Int_Real
)
2062 -- In the floating-point case, we only do range checks if the type is
2063 -- constrained. We definitely do NOT want range checks for unconstrained
2064 -- types, since we want to have infinities
2066 elsif Is_Floating_Point_Type
(S_Typ
) then
2067 if Is_Constrained
(S_Typ
) then
2068 Enable_Range_Check
(Expr
);
2071 -- For all other cases we enable a range check unconditionally
2074 Enable_Range_Check
(Expr
);
2077 end Apply_Scalar_Range_Check
;
2079 ----------------------------------
2080 -- Apply_Selected_Length_Checks --
2081 ----------------------------------
2083 procedure Apply_Selected_Length_Checks
2085 Target_Typ
: Entity_Id
;
2086 Source_Typ
: Entity_Id
;
2087 Do_Static
: Boolean)
2090 R_Result
: Check_Result
;
2093 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
2094 Checks_On
: constant Boolean :=
2095 (not Index_Checks_Suppressed
(Target_Typ
))
2097 (not Length_Checks_Suppressed
(Target_Typ
));
2100 if not Expander_Active
then
2105 Selected_Length_Checks
(Ck_Node
, Target_Typ
, Source_Typ
, Empty
);
2107 for J
in 1 .. 2 loop
2108 R_Cno
:= R_Result
(J
);
2109 exit when No
(R_Cno
);
2111 -- A length check may mention an Itype which is attached to a
2112 -- subsequent node. At the top level in a package this can cause
2113 -- an order-of-elaboration problem, so we make sure that the itype
2114 -- is referenced now.
2116 if Ekind
(Current_Scope
) = E_Package
2117 and then Is_Compilation_Unit
(Current_Scope
)
2119 Ensure_Defined
(Target_Typ
, Ck_Node
);
2121 if Present
(Source_Typ
) then
2122 Ensure_Defined
(Source_Typ
, Ck_Node
);
2124 elsif Is_Itype
(Etype
(Ck_Node
)) then
2125 Ensure_Defined
(Etype
(Ck_Node
), Ck_Node
);
2129 -- If the item is a conditional raise of constraint error, then have
2130 -- a look at what check is being performed and ???
2132 if Nkind
(R_Cno
) = N_Raise_Constraint_Error
2133 and then Present
(Condition
(R_Cno
))
2135 Cond
:= Condition
(R_Cno
);
2137 -- Case where node does not now have a dynamic check
2139 if not Has_Dynamic_Length_Check
(Ck_Node
) then
2141 -- If checks are on, just insert the check
2144 Insert_Action
(Ck_Node
, R_Cno
);
2146 if not Do_Static
then
2147 Set_Has_Dynamic_Length_Check
(Ck_Node
);
2150 -- If checks are off, then analyze the length check after
2151 -- temporarily attaching it to the tree in case the relevant
2152 -- condition can be evaluated at compile time. We still want a
2153 -- compile time warning in this case.
2156 Set_Parent
(R_Cno
, Ck_Node
);
2161 -- Output a warning if the condition is known to be True
2163 if Is_Entity_Name
(Cond
)
2164 and then Entity
(Cond
) = Standard_True
2166 Apply_Compile_Time_Constraint_Error
2167 (Ck_Node
, "wrong length for array of}?",
2168 CE_Length_Check_Failed
,
2172 -- If we were only doing a static check, or if checks are not
2173 -- on, then we want to delete the check, since it is not needed.
2174 -- We do this by replacing the if statement by a null statement
2176 elsif Do_Static
or else not Checks_On
then
2177 Remove_Warning_Messages
(R_Cno
);
2178 Rewrite
(R_Cno
, Make_Null_Statement
(Loc
));
2182 Install_Static_Check
(R_Cno
, Loc
);
2185 end Apply_Selected_Length_Checks
;
2187 ---------------------------------
2188 -- Apply_Selected_Range_Checks --
2189 ---------------------------------
2191 procedure Apply_Selected_Range_Checks
2193 Target_Typ
: Entity_Id
;
2194 Source_Typ
: Entity_Id
;
2195 Do_Static
: Boolean)
2198 R_Result
: Check_Result
;
2201 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
2202 Checks_On
: constant Boolean :=
2203 (not Index_Checks_Suppressed
(Target_Typ
))
2205 (not Range_Checks_Suppressed
(Target_Typ
));
2208 if not Expander_Active
or else not Checks_On
then
2213 Selected_Range_Checks
(Ck_Node
, Target_Typ
, Source_Typ
, Empty
);
2215 for J
in 1 .. 2 loop
2217 R_Cno
:= R_Result
(J
);
2218 exit when No
(R_Cno
);
2220 -- If the item is a conditional raise of constraint error, then have
2221 -- a look at what check is being performed and ???
2223 if Nkind
(R_Cno
) = N_Raise_Constraint_Error
2224 and then Present
(Condition
(R_Cno
))
2226 Cond
:= Condition
(R_Cno
);
2228 if not Has_Dynamic_Range_Check
(Ck_Node
) then
2229 Insert_Action
(Ck_Node
, R_Cno
);
2231 if not Do_Static
then
2232 Set_Has_Dynamic_Range_Check
(Ck_Node
);
2236 -- Output a warning if the condition is known to be True
2238 if Is_Entity_Name
(Cond
)
2239 and then Entity
(Cond
) = Standard_True
2241 -- Since an N_Range is technically not an expression, we have
2242 -- to set one of the bounds to C_E and then just flag the
2243 -- N_Range. The warning message will point to the lower bound
2244 -- and complain about a range, which seems OK.
2246 if Nkind
(Ck_Node
) = N_Range
then
2247 Apply_Compile_Time_Constraint_Error
2248 (Low_Bound
(Ck_Node
), "static range out of bounds of}?",
2249 CE_Range_Check_Failed
,
2253 Set_Raises_Constraint_Error
(Ck_Node
);
2256 Apply_Compile_Time_Constraint_Error
2257 (Ck_Node
, "static value out of range of}?",
2258 CE_Range_Check_Failed
,
2263 -- If we were only doing a static check, or if checks are not
2264 -- on, then we want to delete the check, since it is not needed.
2265 -- We do this by replacing the if statement by a null statement
2267 elsif Do_Static
or else not Checks_On
then
2268 Remove_Warning_Messages
(R_Cno
);
2269 Rewrite
(R_Cno
, Make_Null_Statement
(Loc
));
2273 Install_Static_Check
(R_Cno
, Loc
);
2276 end Apply_Selected_Range_Checks
;
2278 -------------------------------
2279 -- Apply_Static_Length_Check --
2280 -------------------------------
2282 procedure Apply_Static_Length_Check
2284 Target_Typ
: Entity_Id
;
2285 Source_Typ
: Entity_Id
:= Empty
)
2288 Apply_Selected_Length_Checks
2289 (Expr
, Target_Typ
, Source_Typ
, Do_Static
=> True);
2290 end Apply_Static_Length_Check
;
2292 -------------------------------------
2293 -- Apply_Subscript_Validity_Checks --
2294 -------------------------------------
2296 procedure Apply_Subscript_Validity_Checks
(Expr
: Node_Id
) is
2300 pragma Assert
(Nkind
(Expr
) = N_Indexed_Component
);
2302 -- Loop through subscripts
2304 Sub
:= First
(Expressions
(Expr
));
2305 while Present
(Sub
) loop
2307 -- Check one subscript. Note that we do not worry about enumeration
2308 -- type with holes, since we will convert the value to a Pos value
2309 -- for the subscript, and that convert will do the necessary validity
2312 Ensure_Valid
(Sub
, Holes_OK
=> True);
2314 -- Move to next subscript
2318 end Apply_Subscript_Validity_Checks
;
2320 ----------------------------------
2321 -- Apply_Type_Conversion_Checks --
2322 ----------------------------------
2324 procedure Apply_Type_Conversion_Checks
(N
: Node_Id
) is
2325 Target_Type
: constant Entity_Id
:= Etype
(N
);
2326 Target_Base
: constant Entity_Id
:= Base_Type
(Target_Type
);
2327 Expr
: constant Node_Id
:= Expression
(N
);
2328 Expr_Type
: constant Entity_Id
:= Etype
(Expr
);
2331 if Inside_A_Generic
then
2334 -- Skip these checks if serious errors detected, there are some nasty
2335 -- situations of incomplete trees that blow things up.
2337 elsif Serious_Errors_Detected
> 0 then
2340 -- Scalar type conversions of the form Target_Type (Expr) require a
2341 -- range check if we cannot be sure that Expr is in the base type of
2342 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2343 -- are not quite the same condition from an implementation point of
2344 -- view, but clearly the second includes the first.
2346 elsif Is_Scalar_Type
(Target_Type
) then
2348 Conv_OK
: constant Boolean := Conversion_OK
(N
);
2349 -- If the Conversion_OK flag on the type conversion is set and no
2350 -- floating point type is involved in the type conversion then
2351 -- fixed point values must be read as integral values.
2353 Float_To_Int
: constant Boolean :=
2354 Is_Floating_Point_Type
(Expr_Type
)
2355 and then Is_Integer_Type
(Target_Type
);
2358 if not Overflow_Checks_Suppressed
(Target_Base
)
2360 In_Subrange_Of
(Expr_Type
, Target_Base
, Fixed_Int
=> Conv_OK
)
2361 and then not Float_To_Int
2363 Activate_Overflow_Check
(N
);
2366 if not Range_Checks_Suppressed
(Target_Type
)
2367 and then not Range_Checks_Suppressed
(Expr_Type
)
2369 if Float_To_Int
then
2370 Apply_Float_Conversion_Check
(Expr
, Target_Type
);
2372 Apply_Scalar_Range_Check
2373 (Expr
, Target_Type
, Fixed_Int
=> Conv_OK
);
2378 elsif Comes_From_Source
(N
)
2379 and then not Discriminant_Checks_Suppressed
(Target_Type
)
2380 and then Is_Record_Type
(Target_Type
)
2381 and then Is_Derived_Type
(Target_Type
)
2382 and then not Is_Tagged_Type
(Target_Type
)
2383 and then not Is_Constrained
(Target_Type
)
2384 and then Present
(Stored_Constraint
(Target_Type
))
2386 -- An unconstrained derived type may have inherited discriminant
2387 -- Build an actual discriminant constraint list using the stored
2388 -- constraint, to verify that the expression of the parent type
2389 -- satisfies the constraints imposed by the (unconstrained!)
2390 -- derived type. This applies to value conversions, not to view
2391 -- conversions of tagged types.
2394 Loc
: constant Source_Ptr
:= Sloc
(N
);
2396 Constraint
: Elmt_Id
;
2397 Discr_Value
: Node_Id
;
2400 New_Constraints
: constant Elist_Id
:= New_Elmt_List
;
2401 Old_Constraints
: constant Elist_Id
:=
2402 Discriminant_Constraint
(Expr_Type
);
2405 Constraint
:= First_Elmt
(Stored_Constraint
(Target_Type
));
2406 while Present
(Constraint
) loop
2407 Discr_Value
:= Node
(Constraint
);
2409 if Is_Entity_Name
(Discr_Value
)
2410 and then Ekind
(Entity
(Discr_Value
)) = E_Discriminant
2412 Discr
:= Corresponding_Discriminant
(Entity
(Discr_Value
));
2415 and then Scope
(Discr
) = Base_Type
(Expr_Type
)
2417 -- Parent is constrained by new discriminant. Obtain
2418 -- Value of original discriminant in expression. If the
2419 -- new discriminant has been used to constrain more than
2420 -- one of the stored discriminants, this will provide the
2421 -- required consistency check.
2424 (Make_Selected_Component
(Loc
,
2426 Duplicate_Subexpr_No_Checks
2427 (Expr
, Name_Req
=> True),
2429 Make_Identifier
(Loc
, Chars
(Discr
))),
2433 -- Discriminant of more remote ancestor ???
2438 -- Derived type definition has an explicit value for this
2439 -- stored discriminant.
2443 (Duplicate_Subexpr_No_Checks
(Discr_Value
),
2447 Next_Elmt
(Constraint
);
2450 -- Use the unconstrained expression type to retrieve the
2451 -- discriminants of the parent, and apply momentarily the
2452 -- discriminant constraint synthesized above.
2454 Set_Discriminant_Constraint
(Expr_Type
, New_Constraints
);
2455 Cond
:= Build_Discriminant_Checks
(Expr
, Expr_Type
);
2456 Set_Discriminant_Constraint
(Expr_Type
, Old_Constraints
);
2459 Make_Raise_Constraint_Error
(Loc
,
2461 Reason
=> CE_Discriminant_Check_Failed
));
2464 -- For arrays, conversions are applied during expansion, to take into
2465 -- accounts changes of representation. The checks become range checks on
2466 -- the base type or length checks on the subtype, depending on whether
2467 -- the target type is unconstrained or constrained.
2472 end Apply_Type_Conversion_Checks
;
2474 ----------------------------------------------
2475 -- Apply_Universal_Integer_Attribute_Checks --
2476 ----------------------------------------------
2478 procedure Apply_Universal_Integer_Attribute_Checks
(N
: Node_Id
) is
2479 Loc
: constant Source_Ptr
:= Sloc
(N
);
2480 Typ
: constant Entity_Id
:= Etype
(N
);
2483 if Inside_A_Generic
then
2486 -- Nothing to do if checks are suppressed
2488 elsif Range_Checks_Suppressed
(Typ
)
2489 and then Overflow_Checks_Suppressed
(Typ
)
2493 -- Nothing to do if the attribute does not come from source. The
2494 -- internal attributes we generate of this type do not need checks,
2495 -- and furthermore the attempt to check them causes some circular
2496 -- elaboration orders when dealing with packed types.
2498 elsif not Comes_From_Source
(N
) then
2501 -- If the prefix is a selected component that depends on a discriminant
2502 -- the check may improperly expose a discriminant instead of using
2503 -- the bounds of the object itself. Set the type of the attribute to
2504 -- the base type of the context, so that a check will be imposed when
2505 -- needed (e.g. if the node appears as an index).
2507 elsif Nkind
(Prefix
(N
)) = N_Selected_Component
2508 and then Ekind
(Typ
) = E_Signed_Integer_Subtype
2509 and then Depends_On_Discriminant
(Scalar_Range
(Typ
))
2511 Set_Etype
(N
, Base_Type
(Typ
));
2513 -- Otherwise, replace the attribute node with a type conversion node
2514 -- whose expression is the attribute, retyped to universal integer, and
2515 -- whose subtype mark is the target type. The call to analyze this
2516 -- conversion will set range and overflow checks as required for proper
2517 -- detection of an out of range value.
2520 Set_Etype
(N
, Universal_Integer
);
2521 Set_Analyzed
(N
, True);
2524 Make_Type_Conversion
(Loc
,
2525 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
2526 Expression
=> Relocate_Node
(N
)));
2528 Analyze_And_Resolve
(N
, Typ
);
2531 end Apply_Universal_Integer_Attribute_Checks
;
2533 -------------------------------
2534 -- Build_Discriminant_Checks --
2535 -------------------------------
2537 function Build_Discriminant_Checks
2539 T_Typ
: Entity_Id
) return Node_Id
2541 Loc
: constant Source_Ptr
:= Sloc
(N
);
2544 Disc_Ent
: Entity_Id
;
2548 function Aggregate_Discriminant_Val
(Disc
: Entity_Id
) return Node_Id
;
2550 ----------------------------------
2551 -- Aggregate_Discriminant_Value --
2552 ----------------------------------
2554 function Aggregate_Discriminant_Val
(Disc
: Entity_Id
) return Node_Id
is
2558 -- The aggregate has been normalized with named associations. We use
2559 -- the Chars field to locate the discriminant to take into account
2560 -- discriminants in derived types, which carry the same name as those
2563 Assoc
:= First
(Component_Associations
(N
));
2564 while Present
(Assoc
) loop
2565 if Chars
(First
(Choices
(Assoc
))) = Chars
(Disc
) then
2566 return Expression
(Assoc
);
2572 -- Discriminant must have been found in the loop above
2574 raise Program_Error
;
2575 end Aggregate_Discriminant_Val
;
2577 -- Start of processing for Build_Discriminant_Checks
2580 -- Loop through discriminants evolving the condition
2583 Disc
:= First_Elmt
(Discriminant_Constraint
(T_Typ
));
2585 -- For a fully private type, use the discriminants of the parent type
2587 if Is_Private_Type
(T_Typ
)
2588 and then No
(Full_View
(T_Typ
))
2590 Disc_Ent
:= First_Discriminant
(Etype
(Base_Type
(T_Typ
)));
2592 Disc_Ent
:= First_Discriminant
(T_Typ
);
2595 while Present
(Disc
) loop
2596 Dval
:= Node
(Disc
);
2598 if Nkind
(Dval
) = N_Identifier
2599 and then Ekind
(Entity
(Dval
)) = E_Discriminant
2601 Dval
:= New_Occurrence_Of
(Discriminal
(Entity
(Dval
)), Loc
);
2603 Dval
:= Duplicate_Subexpr_No_Checks
(Dval
);
2606 -- If we have an Unchecked_Union node, we can infer the discriminants
2609 if Is_Unchecked_Union
(Base_Type
(T_Typ
)) then
2611 Get_Discriminant_Value
(
2612 First_Discriminant
(T_Typ
),
2614 Stored_Constraint
(T_Typ
)));
2616 elsif Nkind
(N
) = N_Aggregate
then
2618 Duplicate_Subexpr_No_Checks
2619 (Aggregate_Discriminant_Val
(Disc_Ent
));
2623 Make_Selected_Component
(Loc
,
2625 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
2627 Make_Identifier
(Loc
, Chars
(Disc_Ent
)));
2629 Set_Is_In_Discriminant_Check
(Dref
);
2632 Evolve_Or_Else
(Cond
,
2635 Right_Opnd
=> Dval
));
2638 Next_Discriminant
(Disc_Ent
);
2642 end Build_Discriminant_Checks
;
2648 function Check_Needed
(Nod
: Node_Id
; Check
: Check_Type
) return Boolean is
2656 -- Always check if not simple entity
2658 if Nkind
(Nod
) not in N_Has_Entity
2659 or else not Comes_From_Source
(Nod
)
2664 -- Look up tree for short circuit
2671 -- Done if out of subexpression (note that we allow generated stuff
2672 -- such as itype declarations in this context, to keep the loop going
2673 -- since we may well have generated such stuff in complex situations.
2674 -- Also done if no parent (probably an error condition, but no point
2675 -- in behaving nasty if we find it!)
2678 or else (K
not in N_Subexpr
and then Comes_From_Source
(P
))
2682 -- Or/Or Else case, where test is part of the right operand, or is
2683 -- part of one of the actions associated with the right operand, and
2684 -- the left operand is an equality test.
2686 elsif K
= N_Op_Or
then
2687 exit when N
= Right_Opnd
(P
)
2688 and then Nkind
(Left_Opnd
(P
)) = N_Op_Eq
;
2690 elsif K
= N_Or_Else
then
2691 exit when (N
= Right_Opnd
(P
)
2694 and then List_Containing
(N
) = Actions
(P
)))
2695 and then Nkind
(Left_Opnd
(P
)) = N_Op_Eq
;
2697 -- Similar test for the And/And then case, where the left operand
2698 -- is an inequality test.
2700 elsif K
= N_Op_And
then
2701 exit when N
= Right_Opnd
(P
)
2702 and then Nkind
(Left_Opnd
(P
)) = N_Op_Ne
;
2704 elsif K
= N_And_Then
then
2705 exit when (N
= Right_Opnd
(P
)
2708 and then List_Containing
(N
) = Actions
(P
)))
2709 and then Nkind
(Left_Opnd
(P
)) = N_Op_Ne
;
2715 -- If we fall through the loop, then we have a conditional with an
2716 -- appropriate test as its left operand. So test further.
2719 R
:= Right_Opnd
(L
);
2722 -- Left operand of test must match original variable
2724 if Nkind
(L
) not in N_Has_Entity
2725 or else Entity
(L
) /= Entity
(Nod
)
2730 -- Right operand of test must be key value (zero or null)
2733 when Access_Check
=>
2734 if not Known_Null
(R
) then
2738 when Division_Check
=>
2739 if not Compile_Time_Known_Value
(R
)
2740 or else Expr_Value
(R
) /= Uint_0
2746 raise Program_Error
;
2749 -- Here we have the optimizable case, warn if not short-circuited
2751 if K
= N_Op_And
or else K
= N_Op_Or
then
2753 when Access_Check
=>
2755 ("Constraint_Error may be raised (access check)?",
2757 when Division_Check
=>
2759 ("Constraint_Error may be raised (zero divide)?",
2763 raise Program_Error
;
2766 if K
= N_Op_And
then
2767 Error_Msg_N
-- CODEFIX
2768 ("use `AND THEN` instead of AND?", P
);
2770 Error_Msg_N
-- CODEFIX
2771 ("use `OR ELSE` instead of OR?", P
);
2774 -- If not short-circuited, we need the check
2778 -- If short-circuited, we can omit the check
2785 -----------------------------------
2786 -- Check_Valid_Lvalue_Subscripts --
2787 -----------------------------------
2789 procedure Check_Valid_Lvalue_Subscripts
(Expr
: Node_Id
) is
2791 -- Skip this if range checks are suppressed
2793 if Range_Checks_Suppressed
(Etype
(Expr
)) then
2796 -- Only do this check for expressions that come from source. We assume
2797 -- that expander generated assignments explicitly include any necessary
2798 -- checks. Note that this is not just an optimization, it avoids
2799 -- infinite recursions!
2801 elsif not Comes_From_Source
(Expr
) then
2804 -- For a selected component, check the prefix
2806 elsif Nkind
(Expr
) = N_Selected_Component
then
2807 Check_Valid_Lvalue_Subscripts
(Prefix
(Expr
));
2810 -- Case of indexed component
2812 elsif Nkind
(Expr
) = N_Indexed_Component
then
2813 Apply_Subscript_Validity_Checks
(Expr
);
2815 -- Prefix may itself be or contain an indexed component, and these
2816 -- subscripts need checking as well.
2818 Check_Valid_Lvalue_Subscripts
(Prefix
(Expr
));
2820 end Check_Valid_Lvalue_Subscripts
;
2822 ----------------------------------
2823 -- Null_Exclusion_Static_Checks --
2824 ----------------------------------
2826 procedure Null_Exclusion_Static_Checks
(N
: Node_Id
) is
2827 Error_Node
: Node_Id
;
2829 Has_Null
: constant Boolean := Has_Null_Exclusion
(N
);
2830 K
: constant Node_Kind
:= Nkind
(N
);
2835 (K
= N_Component_Declaration
2836 or else K
= N_Discriminant_Specification
2837 or else K
= N_Function_Specification
2838 or else K
= N_Object_Declaration
2839 or else K
= N_Parameter_Specification
);
2841 if K
= N_Function_Specification
then
2842 Typ
:= Etype
(Defining_Entity
(N
));
2844 Typ
:= Etype
(Defining_Identifier
(N
));
2848 when N_Component_Declaration
=>
2849 if Present
(Access_Definition
(Component_Definition
(N
))) then
2850 Error_Node
:= Component_Definition
(N
);
2852 Error_Node
:= Subtype_Indication
(Component_Definition
(N
));
2855 when N_Discriminant_Specification
=>
2856 Error_Node
:= Discriminant_Type
(N
);
2858 when N_Function_Specification
=>
2859 Error_Node
:= Result_Definition
(N
);
2861 when N_Object_Declaration
=>
2862 Error_Node
:= Object_Definition
(N
);
2864 when N_Parameter_Specification
=>
2865 Error_Node
:= Parameter_Type
(N
);
2868 raise Program_Error
;
2873 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2874 -- applied to an access [sub]type.
2876 if not Is_Access_Type
(Typ
) then
2878 ("`NOT NULL` allowed only for an access type", Error_Node
);
2880 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2881 -- be applied to a [sub]type that does not exclude null already.
2883 elsif Can_Never_Be_Null
(Typ
)
2884 and then Comes_From_Source
(Typ
)
2887 ("`NOT NULL` not allowed (& already excludes null)",
2892 -- Check that null-excluding objects are always initialized, except for
2893 -- deferred constants, for which the expression will appear in the full
2896 if K
= N_Object_Declaration
2897 and then No
(Expression
(N
))
2898 and then not Constant_Present
(N
)
2899 and then not No_Initialization
(N
)
2901 -- Add an expression that assigns null. This node is needed by
2902 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2903 -- a Constraint_Error node.
2905 Set_Expression
(N
, Make_Null
(Sloc
(N
)));
2906 Set_Etype
(Expression
(N
), Etype
(Defining_Identifier
(N
)));
2908 Apply_Compile_Time_Constraint_Error
2909 (N
=> Expression
(N
),
2910 Msg
=> "(Ada 2005) null-excluding objects must be initialized?",
2911 Reason
=> CE_Null_Not_Allowed
);
2914 -- Check that a null-excluding component, formal or object is not being
2915 -- assigned a null value. Otherwise generate a warning message and
2916 -- replace Expression (N) by an N_Constraint_Error node.
2918 if K
/= N_Function_Specification
then
2919 Expr
:= Expression
(N
);
2921 if Present
(Expr
) and then Known_Null
(Expr
) then
2923 when N_Component_Declaration |
2924 N_Discriminant_Specification
=>
2925 Apply_Compile_Time_Constraint_Error
2927 Msg
=> "(Ada 2005) null not allowed " &
2928 "in null-excluding components?",
2929 Reason
=> CE_Null_Not_Allowed
);
2931 when N_Object_Declaration
=>
2932 Apply_Compile_Time_Constraint_Error
2934 Msg
=> "(Ada 2005) null not allowed " &
2935 "in null-excluding objects?",
2936 Reason
=> CE_Null_Not_Allowed
);
2938 when N_Parameter_Specification
=>
2939 Apply_Compile_Time_Constraint_Error
2941 Msg
=> "(Ada 2005) null not allowed " &
2942 "in null-excluding formals?",
2943 Reason
=> CE_Null_Not_Allowed
);
2950 end Null_Exclusion_Static_Checks
;
2952 ----------------------------------
2953 -- Conditional_Statements_Begin --
2954 ----------------------------------
2956 procedure Conditional_Statements_Begin
is
2958 Saved_Checks_TOS
:= Saved_Checks_TOS
+ 1;
2960 -- If stack overflows, kill all checks, that way we know to simply reset
2961 -- the number of saved checks to zero on return. This should never occur
2964 if Saved_Checks_TOS
> Saved_Checks_Stack
'Last then
2967 -- In the normal case, we just make a new stack entry saving the current
2968 -- number of saved checks for a later restore.
2971 Saved_Checks_Stack
(Saved_Checks_TOS
) := Num_Saved_Checks
;
2973 if Debug_Flag_CC
then
2974 w
("Conditional_Statements_Begin: Num_Saved_Checks = ",
2978 end Conditional_Statements_Begin
;
2980 --------------------------------
2981 -- Conditional_Statements_End --
2982 --------------------------------
2984 procedure Conditional_Statements_End
is
2986 pragma Assert
(Saved_Checks_TOS
> 0);
2988 -- If the saved checks stack overflowed, then we killed all checks, so
2989 -- setting the number of saved checks back to zero is correct. This
2990 -- should never occur in practice.
2992 if Saved_Checks_TOS
> Saved_Checks_Stack
'Last then
2993 Num_Saved_Checks
:= 0;
2995 -- In the normal case, restore the number of saved checks from the top
2999 Num_Saved_Checks
:= Saved_Checks_Stack
(Saved_Checks_TOS
);
3000 if Debug_Flag_CC
then
3001 w
("Conditional_Statements_End: Num_Saved_Checks = ",
3006 Saved_Checks_TOS
:= Saved_Checks_TOS
- 1;
3007 end Conditional_Statements_End
;
3009 ---------------------
3010 -- Determine_Range --
3011 ---------------------
3013 Cache_Size
: constant := 2 ** 10;
3014 type Cache_Index
is range 0 .. Cache_Size
- 1;
3015 -- Determine size of below cache (power of 2 is more efficient!)
3017 Determine_Range_Cache_N
: array (Cache_Index
) of Node_Id
;
3018 Determine_Range_Cache_V
: array (Cache_Index
) of Boolean;
3019 Determine_Range_Cache_Lo
: array (Cache_Index
) of Uint
;
3020 Determine_Range_Cache_Hi
: array (Cache_Index
) of Uint
;
3021 -- The above arrays are used to implement a small direct cache for
3022 -- Determine_Range calls. Because of the way Determine_Range recursively
3023 -- traces subexpressions, and because overflow checking calls the routine
3024 -- on the way up the tree, a quadratic behavior can otherwise be
3025 -- encountered in large expressions. The cache entry for node N is stored
3026 -- in the (N mod Cache_Size) entry, and can be validated by checking the
3027 -- actual node value stored there. The Range_Cache_V array records the
3028 -- setting of Assume_Valid for the cache entry.
3030 procedure Determine_Range
3035 Assume_Valid
: Boolean := False)
3037 Typ
: Entity_Id
:= Etype
(N
);
3038 -- Type to use, may get reset to base type for possibly invalid entity
3042 -- Lo and Hi bounds of left operand
3046 -- Lo and Hi bounds of right (or only) operand
3049 -- Temp variable used to hold a bound node
3052 -- High bound of base type of expression
3056 -- Refined values for low and high bounds, after tightening
3059 -- Used in lower level calls to indicate if call succeeded
3061 Cindex
: Cache_Index
;
3062 -- Used to search cache
3064 function OK_Operands
return Boolean;
3065 -- Used for binary operators. Determines the ranges of the left and
3066 -- right operands, and if they are both OK, returns True, and puts
3067 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
3073 function OK_Operands
return Boolean is
3076 (Left_Opnd
(N
), OK1
, Lo_Left
, Hi_Left
, Assume_Valid
);
3083 (Right_Opnd
(N
), OK1
, Lo_Right
, Hi_Right
, Assume_Valid
);
3087 -- Start of processing for Determine_Range
3090 -- Prevent junk warnings by initializing range variables
3097 -- If type is not defined, we can't determine its range
3101 -- We don't deal with anything except discrete types
3103 or else not Is_Discrete_Type
(Typ
)
3105 -- Ignore type for which an error has been posted, since range in
3106 -- this case may well be a bogosity deriving from the error. Also
3107 -- ignore if error posted on the reference node.
3109 or else Error_Posted
(N
) or else Error_Posted
(Typ
)
3115 -- For all other cases, we can determine the range
3119 -- If value is compile time known, then the possible range is the one
3120 -- value that we know this expression definitely has!
3122 if Compile_Time_Known_Value
(N
) then
3123 Lo
:= Expr_Value
(N
);
3128 -- Return if already in the cache
3130 Cindex
:= Cache_Index
(N
mod Cache_Size
);
3132 if Determine_Range_Cache_N
(Cindex
) = N
3134 Determine_Range_Cache_V
(Cindex
) = Assume_Valid
3136 Lo
:= Determine_Range_Cache_Lo
(Cindex
);
3137 Hi
:= Determine_Range_Cache_Hi
(Cindex
);
3141 -- Otherwise, start by finding the bounds of the type of the expression,
3142 -- the value cannot be outside this range (if it is, then we have an
3143 -- overflow situation, which is a separate check, we are talking here
3144 -- only about the expression value).
3146 -- First a check, never try to find the bounds of a generic type, since
3147 -- these bounds are always junk values, and it is only valid to look at
3148 -- the bounds in an instance.
3150 if Is_Generic_Type
(Typ
) then
3155 -- First step, change to use base type unless we know the value is valid
3157 if (Is_Entity_Name
(N
) and then Is_Known_Valid
(Entity
(N
)))
3158 or else Assume_No_Invalid_Values
3159 or else Assume_Valid
3163 Typ
:= Underlying_Type
(Base_Type
(Typ
));
3166 -- We use the actual bound unless it is dynamic, in which case use the
3167 -- corresponding base type bound if possible. If we can't get a bound
3168 -- then we figure we can't determine the range (a peculiar case, that
3169 -- perhaps cannot happen, but there is no point in bombing in this
3170 -- optimization circuit.
3172 -- First the low bound
3174 Bound
:= Type_Low_Bound
(Typ
);
3176 if Compile_Time_Known_Value
(Bound
) then
3177 Lo
:= Expr_Value
(Bound
);
3179 elsif Compile_Time_Known_Value
(Type_Low_Bound
(Base_Type
(Typ
))) then
3180 Lo
:= Expr_Value
(Type_Low_Bound
(Base_Type
(Typ
)));
3187 -- Now the high bound
3189 Bound
:= Type_High_Bound
(Typ
);
3191 -- We need the high bound of the base type later on, and this should
3192 -- always be compile time known. Again, it is not clear that this
3193 -- can ever be false, but no point in bombing.
3195 if Compile_Time_Known_Value
(Type_High_Bound
(Base_Type
(Typ
))) then
3196 Hbound
:= Expr_Value
(Type_High_Bound
(Base_Type
(Typ
)));
3204 -- If we have a static subtype, then that may have a tighter bound so
3205 -- use the upper bound of the subtype instead in this case.
3207 if Compile_Time_Known_Value
(Bound
) then
3208 Hi
:= Expr_Value
(Bound
);
3211 -- We may be able to refine this value in certain situations. If any
3212 -- refinement is possible, then Lor and Hir are set to possibly tighter
3213 -- bounds, and OK1 is set to True.
3217 -- For unary plus, result is limited by range of operand
3221 (Right_Opnd
(N
), OK1
, Lor
, Hir
, Assume_Valid
);
3223 -- For unary minus, determine range of operand, and negate it
3227 (Right_Opnd
(N
), OK1
, Lo_Right
, Hi_Right
, Assume_Valid
);
3234 -- For binary addition, get range of each operand and do the
3235 -- addition to get the result range.
3239 Lor
:= Lo_Left
+ Lo_Right
;
3240 Hir
:= Hi_Left
+ Hi_Right
;
3243 -- Division is tricky. The only case we consider is where the right
3244 -- operand is a positive constant, and in this case we simply divide
3245 -- the bounds of the left operand
3249 if Lo_Right
= Hi_Right
3250 and then Lo_Right
> 0
3252 Lor
:= Lo_Left
/ Lo_Right
;
3253 Hir
:= Hi_Left
/ Lo_Right
;
3260 -- For binary subtraction, get range of each operand and do the worst
3261 -- case subtraction to get the result range.
3263 when N_Op_Subtract
=>
3265 Lor
:= Lo_Left
- Hi_Right
;
3266 Hir
:= Hi_Left
- Lo_Right
;
3269 -- For MOD, if right operand is a positive constant, then result must
3270 -- be in the allowable range of mod results.
3274 if Lo_Right
= Hi_Right
3275 and then Lo_Right
/= 0
3277 if Lo_Right
> 0 then
3279 Hir
:= Lo_Right
- 1;
3281 else -- Lo_Right < 0
3282 Lor
:= Lo_Right
+ 1;
3291 -- For REM, if right operand is a positive constant, then result must
3292 -- be in the allowable range of mod results.
3296 if Lo_Right
= Hi_Right
3297 and then Lo_Right
/= 0
3300 Dval
: constant Uint
:= (abs Lo_Right
) - 1;
3303 -- The sign of the result depends on the sign of the
3304 -- dividend (but not on the sign of the divisor, hence
3305 -- the abs operation above).
3325 -- Attribute reference cases
3327 when N_Attribute_Reference
=>
3328 case Attribute_Name
(N
) is
3330 -- For Pos/Val attributes, we can refine the range using the
3331 -- possible range of values of the attribute expression.
3333 when Name_Pos | Name_Val
=>
3335 (First
(Expressions
(N
)), OK1
, Lor
, Hir
, Assume_Valid
);
3337 -- For Length attribute, use the bounds of the corresponding
3338 -- index type to refine the range.
3342 Atyp
: Entity_Id
:= Etype
(Prefix
(N
));
3350 if Is_Access_Type
(Atyp
) then
3351 Atyp
:= Designated_Type
(Atyp
);
3354 -- For string literal, we know exact value
3356 if Ekind
(Atyp
) = E_String_Literal_Subtype
then
3358 Lo
:= String_Literal_Length
(Atyp
);
3359 Hi
:= String_Literal_Length
(Atyp
);
3363 -- Otherwise check for expression given
3365 if No
(Expressions
(N
)) then
3369 UI_To_Int
(Expr_Value
(First
(Expressions
(N
))));
3372 Indx
:= First_Index
(Atyp
);
3373 for J
in 2 .. Inum
loop
3374 Indx
:= Next_Index
(Indx
);
3377 -- If the index type is a formal type or derived from
3378 -- one, the bounds are not static.
3380 if Is_Generic_Type
(Root_Type
(Etype
(Indx
))) then
3386 (Type_Low_Bound
(Etype
(Indx
)), OK1
, LL
, LU
,
3391 (Type_High_Bound
(Etype
(Indx
)), OK1
, UL
, UU
,
3396 -- The maximum value for Length is the biggest
3397 -- possible gap between the values of the bounds.
3398 -- But of course, this value cannot be negative.
3400 Hir
:= UI_Max
(Uint_0
, UU
- LL
+ 1);
3402 -- For constrained arrays, the minimum value for
3403 -- Length is taken from the actual value of the
3404 -- bounds, since the index will be exactly of this
3407 if Is_Constrained
(Atyp
) then
3408 Lor
:= UI_Max
(Uint_0
, UL
- LU
+ 1);
3410 -- For an unconstrained array, the minimum value
3411 -- for length is always zero.
3420 -- No special handling for other attributes
3421 -- Probably more opportunities exist here???
3428 -- For type conversion from one discrete type to another, we can
3429 -- refine the range using the converted value.
3431 when N_Type_Conversion
=>
3432 Determine_Range
(Expression
(N
), OK1
, Lor
, Hir
, Assume_Valid
);
3434 -- Nothing special to do for all other expression kinds
3442 -- At this stage, if OK1 is true, then we know that the actual result of
3443 -- the computed expression is in the range Lor .. Hir. We can use this
3444 -- to restrict the possible range of results.
3448 -- If the refined value of the low bound is greater than the type
3449 -- high bound, then reset it to the more restrictive value. However,
3450 -- we do NOT do this for the case of a modular type where the
3451 -- possible upper bound on the value is above the base type high
3452 -- bound, because that means the result could wrap.
3455 and then not (Is_Modular_Integer_Type
(Typ
) and then Hir
> Hbound
)
3460 -- Similarly, if the refined value of the high bound is less than the
3461 -- value so far, then reset it to the more restrictive value. Again,
3462 -- we do not do this if the refined low bound is negative for a
3463 -- modular type, since this would wrap.
3466 and then not (Is_Modular_Integer_Type
(Typ
) and then Lor
< Uint_0
)
3472 -- Set cache entry for future call and we are all done
3474 Determine_Range_Cache_N
(Cindex
) := N
;
3475 Determine_Range_Cache_V
(Cindex
) := Assume_Valid
;
3476 Determine_Range_Cache_Lo
(Cindex
) := Lo
;
3477 Determine_Range_Cache_Hi
(Cindex
) := Hi
;
3480 -- If any exception occurs, it means that we have some bug in the compiler,
3481 -- possibly triggered by a previous error, or by some unforeseen peculiar
3482 -- occurrence. However, this is only an optimization attempt, so there is
3483 -- really no point in crashing the compiler. Instead we just decide, too
3484 -- bad, we can't figure out a range in this case after all.
3489 -- Debug flag K disables this behavior (useful for debugging)
3491 if Debug_Flag_K
then
3499 end Determine_Range
;
3501 ------------------------------------
3502 -- Discriminant_Checks_Suppressed --
3503 ------------------------------------
3505 function Discriminant_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
3508 if Is_Unchecked_Union
(E
) then
3510 elsif Checks_May_Be_Suppressed
(E
) then
3511 return Is_Check_Suppressed
(E
, Discriminant_Check
);
3515 return Scope_Suppress
(Discriminant_Check
);
3516 end Discriminant_Checks_Suppressed
;
3518 --------------------------------
3519 -- Division_Checks_Suppressed --
3520 --------------------------------
3522 function Division_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
3524 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
3525 return Is_Check_Suppressed
(E
, Division_Check
);
3527 return Scope_Suppress
(Division_Check
);
3529 end Division_Checks_Suppressed
;
3531 -----------------------------------
3532 -- Elaboration_Checks_Suppressed --
3533 -----------------------------------
3535 function Elaboration_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
3537 -- The complication in this routine is that if we are in the dynamic
3538 -- model of elaboration, we also check All_Checks, since All_Checks
3539 -- does not set Elaboration_Check explicitly.
3542 if Kill_Elaboration_Checks
(E
) then
3545 elsif Checks_May_Be_Suppressed
(E
) then
3546 if Is_Check_Suppressed
(E
, Elaboration_Check
) then
3548 elsif Dynamic_Elaboration_Checks
then
3549 return Is_Check_Suppressed
(E
, All_Checks
);
3556 if Scope_Suppress
(Elaboration_Check
) then
3558 elsif Dynamic_Elaboration_Checks
then
3559 return Scope_Suppress
(All_Checks
);
3563 end Elaboration_Checks_Suppressed
;
3565 ---------------------------
3566 -- Enable_Overflow_Check --
3567 ---------------------------
3569 procedure Enable_Overflow_Check
(N
: Node_Id
) is
3570 Typ
: constant Entity_Id
:= Base_Type
(Etype
(N
));
3579 if Debug_Flag_CC
then
3580 w
("Enable_Overflow_Check for node ", Int
(N
));
3581 Write_Str
(" Source location = ");
3586 -- No check if overflow checks suppressed for type of node
3588 if Present
(Etype
(N
))
3589 and then Overflow_Checks_Suppressed
(Etype
(N
))
3593 -- Nothing to do for unsigned integer types, which do not overflow
3595 elsif Is_Modular_Integer_Type
(Typ
) then
3598 -- Nothing to do if the range of the result is known OK. We skip this
3599 -- for conversions, since the caller already did the check, and in any
3600 -- case the condition for deleting the check for a type conversion is
3603 elsif Nkind
(N
) /= N_Type_Conversion
then
3604 Determine_Range
(N
, OK
, Lo
, Hi
, Assume_Valid
=> True);
3606 -- Note in the test below that we assume that the range is not OK
3607 -- if a bound of the range is equal to that of the type. That's not
3608 -- quite accurate but we do this for the following reasons:
3610 -- a) The way that Determine_Range works, it will typically report
3611 -- the bounds of the value as being equal to the bounds of the
3612 -- type, because it either can't tell anything more precise, or
3613 -- does not think it is worth the effort to be more precise.
3615 -- b) It is very unusual to have a situation in which this would
3616 -- generate an unnecessary overflow check (an example would be
3617 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3618 -- literal value one is added).
3620 -- c) The alternative is a lot of special casing in this routine
3621 -- which would partially duplicate Determine_Range processing.
3624 and then Lo
> Expr_Value
(Type_Low_Bound
(Typ
))
3625 and then Hi
< Expr_Value
(Type_High_Bound
(Typ
))
3627 if Debug_Flag_CC
then
3628 w
("No overflow check required");
3635 -- If not in optimizing mode, set flag and we are done. We are also done
3636 -- (and just set the flag) if the type is not a discrete type, since it
3637 -- is not worth the effort to eliminate checks for other than discrete
3638 -- types. In addition, we take this same path if we have stored the
3639 -- maximum number of checks possible already (a very unlikely situation,
3640 -- but we do not want to blow up!)
3642 if Optimization_Level
= 0
3643 or else not Is_Discrete_Type
(Etype
(N
))
3644 or else Num_Saved_Checks
= Saved_Checks
'Last
3646 Activate_Overflow_Check
(N
);
3648 if Debug_Flag_CC
then
3649 w
("Optimization off");
3655 -- Otherwise evaluate and check the expression
3660 Target_Type
=> Empty
,
3666 if Debug_Flag_CC
then
3667 w
("Called Find_Check");
3671 w
(" Check_Num = ", Chk
);
3672 w
(" Ent = ", Int
(Ent
));
3673 Write_Str
(" Ofs = ");
3678 -- If check is not of form to optimize, then set flag and we are done
3681 Activate_Overflow_Check
(N
);
3685 -- If check is already performed, then return without setting flag
3688 if Debug_Flag_CC
then
3689 w
("Check suppressed!");
3695 -- Here we will make a new entry for the new check
3697 Activate_Overflow_Check
(N
);
3698 Num_Saved_Checks
:= Num_Saved_Checks
+ 1;
3699 Saved_Checks
(Num_Saved_Checks
) :=
3704 Target_Type
=> Empty
);
3706 if Debug_Flag_CC
then
3707 w
("Make new entry, check number = ", Num_Saved_Checks
);
3708 w
(" Entity = ", Int
(Ent
));
3709 Write_Str
(" Offset = ");
3711 w
(" Check_Type = O");
3712 w
(" Target_Type = Empty");
3715 -- If we get an exception, then something went wrong, probably because of
3716 -- an error in the structure of the tree due to an incorrect program. Or it
3717 -- may be a bug in the optimization circuit. In either case the safest
3718 -- thing is simply to set the check flag unconditionally.
3722 Activate_Overflow_Check
(N
);
3724 if Debug_Flag_CC
then
3725 w
(" exception occurred, overflow flag set");
3729 end Enable_Overflow_Check
;
3731 ------------------------
3732 -- Enable_Range_Check --
3733 ------------------------
3735 procedure Enable_Range_Check
(N
: Node_Id
) is
3744 -- Return if unchecked type conversion with range check killed. In this
3745 -- case we never set the flag (that's what Kill_Range_Check is about!)
3747 if Nkind
(N
) = N_Unchecked_Type_Conversion
3748 and then Kill_Range_Check
(N
)
3753 -- Do not set range check flag if parent is assignment statement or
3754 -- object declaration with Suppress_Assignment_Checks flag set
3756 if Nkind_In
(Parent
(N
), N_Assignment_Statement
, N_Object_Declaration
)
3757 and then Suppress_Assignment_Checks
(Parent
(N
))
3762 -- Check for various cases where we should suppress the range check
3764 -- No check if range checks suppressed for type of node
3766 if Present
(Etype
(N
))
3767 and then Range_Checks_Suppressed
(Etype
(N
))
3771 -- No check if node is an entity name, and range checks are suppressed
3772 -- for this entity, or for the type of this entity.
3774 elsif Is_Entity_Name
(N
)
3775 and then (Range_Checks_Suppressed
(Entity
(N
))
3776 or else Range_Checks_Suppressed
(Etype
(Entity
(N
))))
3780 -- No checks if index of array, and index checks are suppressed for
3781 -- the array object or the type of the array.
3783 elsif Nkind
(Parent
(N
)) = N_Indexed_Component
then
3785 Pref
: constant Node_Id
:= Prefix
(Parent
(N
));
3787 if Is_Entity_Name
(Pref
)
3788 and then Index_Checks_Suppressed
(Entity
(Pref
))
3791 elsif Index_Checks_Suppressed
(Etype
(Pref
)) then
3797 -- Debug trace output
3799 if Debug_Flag_CC
then
3800 w
("Enable_Range_Check for node ", Int
(N
));
3801 Write_Str
(" Source location = ");
3806 -- If not in optimizing mode, set flag and we are done. We are also done
3807 -- (and just set the flag) if the type is not a discrete type, since it
3808 -- is not worth the effort to eliminate checks for other than discrete
3809 -- types. In addition, we take this same path if we have stored the
3810 -- maximum number of checks possible already (a very unlikely situation,
3811 -- but we do not want to blow up!)
3813 if Optimization_Level
= 0
3814 or else No
(Etype
(N
))
3815 or else not Is_Discrete_Type
(Etype
(N
))
3816 or else Num_Saved_Checks
= Saved_Checks
'Last
3818 Activate_Range_Check
(N
);
3820 if Debug_Flag_CC
then
3821 w
("Optimization off");
3827 -- Otherwise find out the target type
3831 -- For assignment, use left side subtype
3833 if Nkind
(P
) = N_Assignment_Statement
3834 and then Expression
(P
) = N
3836 Ttyp
:= Etype
(Name
(P
));
3838 -- For indexed component, use subscript subtype
3840 elsif Nkind
(P
) = N_Indexed_Component
then
3847 Atyp
:= Etype
(Prefix
(P
));
3849 if Is_Access_Type
(Atyp
) then
3850 Atyp
:= Designated_Type
(Atyp
);
3852 -- If the prefix is an access to an unconstrained array,
3853 -- perform check unconditionally: it depends on the bounds of
3854 -- an object and we cannot currently recognize whether the test
3855 -- may be redundant.
3857 if not Is_Constrained
(Atyp
) then
3858 Activate_Range_Check
(N
);
3862 -- Ditto if the prefix is an explicit dereference whose designated
3863 -- type is unconstrained.
3865 elsif Nkind
(Prefix
(P
)) = N_Explicit_Dereference
3866 and then not Is_Constrained
(Atyp
)
3868 Activate_Range_Check
(N
);
3872 Indx
:= First_Index
(Atyp
);
3873 Subs
:= First
(Expressions
(P
));
3876 Ttyp
:= Etype
(Indx
);
3885 -- For now, ignore all other cases, they are not so interesting
3888 if Debug_Flag_CC
then
3889 w
(" target type not found, flag set");
3892 Activate_Range_Check
(N
);
3896 -- Evaluate and check the expression
3901 Target_Type
=> Ttyp
,
3907 if Debug_Flag_CC
then
3908 w
("Called Find_Check");
3909 w
("Target_Typ = ", Int
(Ttyp
));
3913 w
(" Check_Num = ", Chk
);
3914 w
(" Ent = ", Int
(Ent
));
3915 Write_Str
(" Ofs = ");
3920 -- If check is not of form to optimize, then set flag and we are done
3923 if Debug_Flag_CC
then
3924 w
(" expression not of optimizable type, flag set");
3927 Activate_Range_Check
(N
);
3931 -- If check is already performed, then return without setting flag
3934 if Debug_Flag_CC
then
3935 w
("Check suppressed!");
3941 -- Here we will make a new entry for the new check
3943 Activate_Range_Check
(N
);
3944 Num_Saved_Checks
:= Num_Saved_Checks
+ 1;
3945 Saved_Checks
(Num_Saved_Checks
) :=
3950 Target_Type
=> Ttyp
);
3952 if Debug_Flag_CC
then
3953 w
("Make new entry, check number = ", Num_Saved_Checks
);
3954 w
(" Entity = ", Int
(Ent
));
3955 Write_Str
(" Offset = ");
3957 w
(" Check_Type = R");
3958 w
(" Target_Type = ", Int
(Ttyp
));
3959 pg
(Union_Id
(Ttyp
));
3962 -- If we get an exception, then something went wrong, probably because of
3963 -- an error in the structure of the tree due to an incorrect program. Or
3964 -- it may be a bug in the optimization circuit. In either case the safest
3965 -- thing is simply to set the check flag unconditionally.
3969 Activate_Range_Check
(N
);
3971 if Debug_Flag_CC
then
3972 w
(" exception occurred, range flag set");
3976 end Enable_Range_Check
;
3982 procedure Ensure_Valid
(Expr
: Node_Id
; Holes_OK
: Boolean := False) is
3983 Typ
: constant Entity_Id
:= Etype
(Expr
);
3986 -- Ignore call if we are not doing any validity checking
3988 if not Validity_Checks_On
then
3991 -- Ignore call if range or validity checks suppressed on entity or type
3993 elsif Range_Or_Validity_Checks_Suppressed
(Expr
) then
3996 -- No check required if expression is from the expander, we assume the
3997 -- expander will generate whatever checks are needed. Note that this is
3998 -- not just an optimization, it avoids infinite recursions!
4000 -- Unchecked conversions must be checked, unless they are initialized
4001 -- scalar values, as in a component assignment in an init proc.
4003 -- In addition, we force a check if Force_Validity_Checks is set
4005 elsif not Comes_From_Source
(Expr
)
4006 and then not Force_Validity_Checks
4007 and then (Nkind
(Expr
) /= N_Unchecked_Type_Conversion
4008 or else Kill_Range_Check
(Expr
))
4012 -- No check required if expression is known to have valid value
4014 elsif Expr_Known_Valid
(Expr
) then
4017 -- Ignore case of enumeration with holes where the flag is set not to
4018 -- worry about holes, since no special validity check is needed
4020 elsif Is_Enumeration_Type
(Typ
)
4021 and then Has_Non_Standard_Rep
(Typ
)
4026 -- No check required on the left-hand side of an assignment
4028 elsif Nkind
(Parent
(Expr
)) = N_Assignment_Statement
4029 and then Expr
= Name
(Parent
(Expr
))
4033 -- No check on a universal real constant. The context will eventually
4034 -- convert it to a machine number for some target type, or report an
4037 elsif Nkind
(Expr
) = N_Real_Literal
4038 and then Etype
(Expr
) = Universal_Real
4042 -- If the expression denotes a component of a packed boolean array,
4043 -- no possible check applies. We ignore the old ACATS chestnuts that
4044 -- involve Boolean range True..True.
4046 -- Note: validity checks are generated for expressions that yield a
4047 -- scalar type, when it is possible to create a value that is outside of
4048 -- the type. If this is a one-bit boolean no such value exists. This is
4049 -- an optimization, and it also prevents compiler blowing up during the
4050 -- elaboration of improperly expanded packed array references.
4052 elsif Nkind
(Expr
) = N_Indexed_Component
4053 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Expr
)))
4054 and then Root_Type
(Etype
(Expr
)) = Standard_Boolean
4058 -- An annoying special case. If this is an out parameter of a scalar
4059 -- type, then the value is not going to be accessed, therefore it is
4060 -- inappropriate to do any validity check at the call site.
4063 -- Only need to worry about scalar types
4065 if Is_Scalar_Type
(Typ
) then
4075 -- Find actual argument (which may be a parameter association)
4076 -- and the parent of the actual argument (the call statement)
4081 if Nkind
(P
) = N_Parameter_Association
then
4086 -- Only need to worry if we are argument of a procedure call
4087 -- since functions don't have out parameters. If this is an
4088 -- indirect or dispatching call, get signature from the
4091 if Nkind
(P
) = N_Procedure_Call_Statement
then
4092 L
:= Parameter_Associations
(P
);
4094 if Is_Entity_Name
(Name
(P
)) then
4095 E
:= Entity
(Name
(P
));
4097 pragma Assert
(Nkind
(Name
(P
)) = N_Explicit_Dereference
);
4098 E
:= Etype
(Name
(P
));
4101 -- Only need to worry if there are indeed actuals, and if
4102 -- this could be a procedure call, otherwise we cannot get a
4103 -- match (either we are not an argument, or the mode of the
4104 -- formal is not OUT). This test also filters out the
4107 if Is_Non_Empty_List
(L
)
4108 and then Is_Subprogram
(E
)
4110 -- This is the loop through parameters, looking for an
4111 -- OUT parameter for which we are the argument.
4113 F
:= First_Formal
(E
);
4115 while Present
(F
) loop
4116 if Ekind
(F
) = E_Out_Parameter
and then A
= N
then
4129 -- If this is a boolean expression, only its elementary operands need
4130 -- checking: if they are valid, a boolean or short-circuit operation
4131 -- with them will be valid as well.
4133 if Base_Type
(Typ
) = Standard_Boolean
4135 (Nkind
(Expr
) in N_Op
or else Nkind
(Expr
) in N_Short_Circuit
)
4140 -- If we fall through, a validity check is required
4142 Insert_Valid_Check
(Expr
);
4144 if Is_Entity_Name
(Expr
)
4145 and then Safe_To_Capture_Value
(Expr
, Entity
(Expr
))
4147 Set_Is_Known_Valid
(Entity
(Expr
));
4151 ----------------------
4152 -- Expr_Known_Valid --
4153 ----------------------
4155 function Expr_Known_Valid
(Expr
: Node_Id
) return Boolean is
4156 Typ
: constant Entity_Id
:= Etype
(Expr
);
4159 -- Non-scalar types are always considered valid, since they never give
4160 -- rise to the issues of erroneous or bounded error behavior that are
4161 -- the concern. In formal reference manual terms the notion of validity
4162 -- only applies to scalar types. Note that even when packed arrays are
4163 -- represented using modular types, they are still arrays semantically,
4164 -- so they are also always valid (in particular, the unused bits can be
4165 -- random rubbish without affecting the validity of the array value).
4167 if not Is_Scalar_Type
(Typ
) or else Is_Packed_Array_Type
(Typ
) then
4170 -- If no validity checking, then everything is considered valid
4172 elsif not Validity_Checks_On
then
4175 -- Floating-point types are considered valid unless floating-point
4176 -- validity checks have been specifically turned on.
4178 elsif Is_Floating_Point_Type
(Typ
)
4179 and then not Validity_Check_Floating_Point
4183 -- If the expression is the value of an object that is known to be
4184 -- valid, then clearly the expression value itself is valid.
4186 elsif Is_Entity_Name
(Expr
)
4187 and then Is_Known_Valid
(Entity
(Expr
))
4191 -- References to discriminants are always considered valid. The value
4192 -- of a discriminant gets checked when the object is built. Within the
4193 -- record, we consider it valid, and it is important to do so, since
4194 -- otherwise we can try to generate bogus validity checks which
4195 -- reference discriminants out of scope. Discriminants of concurrent
4196 -- types are excluded for the same reason.
4198 elsif Is_Entity_Name
(Expr
)
4199 and then Denotes_Discriminant
(Expr
, Check_Concurrent
=> True)
4203 -- If the type is one for which all values are known valid, then we are
4204 -- sure that the value is valid except in the slightly odd case where
4205 -- the expression is a reference to a variable whose size has been
4206 -- explicitly set to a value greater than the object size.
4208 elsif Is_Known_Valid
(Typ
) then
4209 if Is_Entity_Name
(Expr
)
4210 and then Ekind
(Entity
(Expr
)) = E_Variable
4211 and then Esize
(Entity
(Expr
)) > Esize
(Typ
)
4218 -- Integer and character literals always have valid values, where
4219 -- appropriate these will be range checked in any case.
4221 elsif Nkind
(Expr
) = N_Integer_Literal
4223 Nkind
(Expr
) = N_Character_Literal
4227 -- If we have a type conversion or a qualification of a known valid
4228 -- value, then the result will always be valid.
4230 elsif Nkind
(Expr
) = N_Type_Conversion
4232 Nkind
(Expr
) = N_Qualified_Expression
4234 return Expr_Known_Valid
(Expression
(Expr
));
4236 -- The result of any operator is always considered valid, since we
4237 -- assume the necessary checks are done by the operator. For operators
4238 -- on floating-point operations, we must also check when the operation
4239 -- is the right-hand side of an assignment, or is an actual in a call.
4241 elsif Nkind
(Expr
) in N_Op
then
4242 if Is_Floating_Point_Type
(Typ
)
4243 and then Validity_Check_Floating_Point
4245 (Nkind
(Parent
(Expr
)) = N_Assignment_Statement
4246 or else Nkind
(Parent
(Expr
)) = N_Function_Call
4247 or else Nkind
(Parent
(Expr
)) = N_Parameter_Association
)
4254 -- The result of a membership test is always valid, since it is true or
4255 -- false, there are no other possibilities.
4257 elsif Nkind
(Expr
) in N_Membership_Test
then
4260 -- For all other cases, we do not know the expression is valid
4265 end Expr_Known_Valid
;
4271 procedure Find_Check
4273 Check_Type
: Character;
4274 Target_Type
: Entity_Id
;
4275 Entry_OK
: out Boolean;
4276 Check_Num
: out Nat
;
4277 Ent
: out Entity_Id
;
4280 function Within_Range_Of
4281 (Target_Type
: Entity_Id
;
4282 Check_Type
: Entity_Id
) return Boolean;
4283 -- Given a requirement for checking a range against Target_Type, and
4284 -- and a range Check_Type against which a check has already been made,
4285 -- determines if the check against check type is sufficient to ensure
4286 -- that no check against Target_Type is required.
4288 ---------------------
4289 -- Within_Range_Of --
4290 ---------------------
4292 function Within_Range_Of
4293 (Target_Type
: Entity_Id
;
4294 Check_Type
: Entity_Id
) return Boolean
4297 if Target_Type
= Check_Type
then
4302 Tlo
: constant Node_Id
:= Type_Low_Bound
(Target_Type
);
4303 Thi
: constant Node_Id
:= Type_High_Bound
(Target_Type
);
4304 Clo
: constant Node_Id
:= Type_Low_Bound
(Check_Type
);
4305 Chi
: constant Node_Id
:= Type_High_Bound
(Check_Type
);
4309 or else (Compile_Time_Known_Value
(Tlo
)
4311 Compile_Time_Known_Value
(Clo
)
4313 Expr_Value
(Clo
) >= Expr_Value
(Tlo
)))
4316 or else (Compile_Time_Known_Value
(Thi
)
4318 Compile_Time_Known_Value
(Chi
)
4320 Expr_Value
(Chi
) <= Expr_Value
(Clo
)))
4328 end Within_Range_Of
;
4330 -- Start of processing for Find_Check
4333 -- Establish default, in case no entry is found
4337 -- Case of expression is simple entity reference
4339 if Is_Entity_Name
(Expr
) then
4340 Ent
:= Entity
(Expr
);
4343 -- Case of expression is entity + known constant
4345 elsif Nkind
(Expr
) = N_Op_Add
4346 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
4347 and then Is_Entity_Name
(Left_Opnd
(Expr
))
4349 Ent
:= Entity
(Left_Opnd
(Expr
));
4350 Ofs
:= Expr_Value
(Right_Opnd
(Expr
));
4352 -- Case of expression is entity - known constant
4354 elsif Nkind
(Expr
) = N_Op_Subtract
4355 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
4356 and then Is_Entity_Name
(Left_Opnd
(Expr
))
4358 Ent
:= Entity
(Left_Opnd
(Expr
));
4359 Ofs
:= UI_Negate
(Expr_Value
(Right_Opnd
(Expr
)));
4361 -- Any other expression is not of the right form
4370 -- Come here with expression of appropriate form, check if entity is an
4371 -- appropriate one for our purposes.
4373 if (Ekind
(Ent
) = E_Variable
4374 or else Is_Constant_Object
(Ent
))
4375 and then not Is_Library_Level_Entity
(Ent
)
4383 -- See if there is matching check already
4385 for J
in reverse 1 .. Num_Saved_Checks
loop
4387 SC
: Saved_Check
renames Saved_Checks
(J
);
4390 if SC
.Killed
= False
4391 and then SC
.Entity
= Ent
4392 and then SC
.Offset
= Ofs
4393 and then SC
.Check_Type
= Check_Type
4394 and then Within_Range_Of
(Target_Type
, SC
.Target_Type
)
4402 -- If we fall through entry was not found
4407 ---------------------------------
4408 -- Generate_Discriminant_Check --
4409 ---------------------------------
4411 -- Note: the code for this procedure is derived from the
4412 -- Emit_Discriminant_Check Routine in trans.c.
4414 procedure Generate_Discriminant_Check
(N
: Node_Id
) is
4415 Loc
: constant Source_Ptr
:= Sloc
(N
);
4416 Pref
: constant Node_Id
:= Prefix
(N
);
4417 Sel
: constant Node_Id
:= Selector_Name
(N
);
4419 Orig_Comp
: constant Entity_Id
:=
4420 Original_Record_Component
(Entity
(Sel
));
4421 -- The original component to be checked
4423 Discr_Fct
: constant Entity_Id
:=
4424 Discriminant_Checking_Func
(Orig_Comp
);
4425 -- The discriminant checking function
4428 -- One discriminant to be checked in the type
4430 Real_Discr
: Entity_Id
;
4431 -- Actual discriminant in the call
4433 Pref_Type
: Entity_Id
;
4434 -- Type of relevant prefix (ignoring private/access stuff)
4437 -- List of arguments for function call
4440 -- Keep track of the formal corresponding to the actual we build for
4441 -- each discriminant, in order to be able to perform the necessary type
4445 -- Selected component reference for checking function argument
4448 Pref_Type
:= Etype
(Pref
);
4450 -- Force evaluation of the prefix, so that it does not get evaluated
4451 -- twice (once for the check, once for the actual reference). Such a
4452 -- double evaluation is always a potential source of inefficiency,
4453 -- and is functionally incorrect in the volatile case, or when the
4454 -- prefix may have side-effects. An entity or a component of an
4455 -- entity requires no evaluation.
4457 if Is_Entity_Name
(Pref
) then
4458 if Treat_As_Volatile
(Entity
(Pref
)) then
4459 Force_Evaluation
(Pref
, Name_Req
=> True);
4462 elsif Treat_As_Volatile
(Etype
(Pref
)) then
4463 Force_Evaluation
(Pref
, Name_Req
=> True);
4465 elsif Nkind
(Pref
) = N_Selected_Component
4466 and then Is_Entity_Name
(Prefix
(Pref
))
4471 Force_Evaluation
(Pref
, Name_Req
=> True);
4474 -- For a tagged type, use the scope of the original component to
4475 -- obtain the type, because ???
4477 if Is_Tagged_Type
(Scope
(Orig_Comp
)) then
4478 Pref_Type
:= Scope
(Orig_Comp
);
4480 -- For an untagged derived type, use the discriminants of the parent
4481 -- which have been renamed in the derivation, possibly by a one-to-many
4482 -- discriminant constraint. For non-tagged type, initially get the Etype
4486 if Is_Derived_Type
(Pref_Type
)
4487 and then Number_Discriminants
(Pref_Type
) /=
4488 Number_Discriminants
(Etype
(Base_Type
(Pref_Type
)))
4490 Pref_Type
:= Etype
(Base_Type
(Pref_Type
));
4494 -- We definitely should have a checking function, This routine should
4495 -- not be called if no discriminant checking function is present.
4497 pragma Assert
(Present
(Discr_Fct
));
4499 -- Create the list of the actual parameters for the call. This list
4500 -- is the list of the discriminant fields of the record expression to
4501 -- be discriminant checked.
4504 Formal
:= First_Formal
(Discr_Fct
);
4505 Discr
:= First_Discriminant
(Pref_Type
);
4506 while Present
(Discr
) loop
4508 -- If we have a corresponding discriminant field, and a parent
4509 -- subtype is present, then we want to use the corresponding
4510 -- discriminant since this is the one with the useful value.
4512 if Present
(Corresponding_Discriminant
(Discr
))
4513 and then Ekind
(Pref_Type
) = E_Record_Type
4514 and then Present
(Parent_Subtype
(Pref_Type
))
4516 Real_Discr
:= Corresponding_Discriminant
(Discr
);
4518 Real_Discr
:= Discr
;
4521 -- Construct the reference to the discriminant
4524 Make_Selected_Component
(Loc
,
4526 Unchecked_Convert_To
(Pref_Type
,
4527 Duplicate_Subexpr
(Pref
)),
4528 Selector_Name
=> New_Occurrence_Of
(Real_Discr
, Loc
));
4530 -- Manually analyze and resolve this selected component. We really
4531 -- want it just as it appears above, and do not want the expander
4532 -- playing discriminal games etc with this reference. Then we append
4533 -- the argument to the list we are gathering.
4535 Set_Etype
(Scomp
, Etype
(Real_Discr
));
4536 Set_Analyzed
(Scomp
, True);
4537 Append_To
(Args
, Convert_To
(Etype
(Formal
), Scomp
));
4539 Next_Formal_With_Extras
(Formal
);
4540 Next_Discriminant
(Discr
);
4543 -- Now build and insert the call
4546 Make_Raise_Constraint_Error
(Loc
,
4548 Make_Function_Call
(Loc
,
4549 Name
=> New_Occurrence_Of
(Discr_Fct
, Loc
),
4550 Parameter_Associations
=> Args
),
4551 Reason
=> CE_Discriminant_Check_Failed
));
4552 end Generate_Discriminant_Check
;
4554 ---------------------------
4555 -- Generate_Index_Checks --
4556 ---------------------------
4558 procedure Generate_Index_Checks
(N
: Node_Id
) is
4559 Loc
: constant Source_Ptr
:= Sloc
(N
);
4560 A
: constant Node_Id
:= Prefix
(N
);
4566 -- Ignore call if index checks suppressed for array object or type
4568 if (Is_Entity_Name
(A
) and then Index_Checks_Suppressed
(Entity
(A
)))
4569 or else Index_Checks_Suppressed
(Etype
(A
))
4574 -- Generate the checks
4576 Sub
:= First
(Expressions
(N
));
4578 while Present
(Sub
) loop
4579 if Do_Range_Check
(Sub
) then
4580 Set_Do_Range_Check
(Sub
, False);
4582 -- Force evaluation except for the case of a simple name of a
4583 -- non-volatile entity.
4585 if not Is_Entity_Name
(Sub
)
4586 or else Treat_As_Volatile
(Entity
(Sub
))
4588 Force_Evaluation
(Sub
);
4591 -- Generate a raise of constraint error with the appropriate
4592 -- reason and a condition of the form:
4594 -- Base_Type(Sub) not in array'range (subscript)
4596 -- Note that the reason we generate the conversion to the base
4597 -- type here is that we definitely want the range check to take
4598 -- place, even if it looks like the subtype is OK. Optimization
4599 -- considerations that allow us to omit the check have already
4600 -- been taken into account in the setting of the Do_Range_Check
4606 Num
:= New_List
(Make_Integer_Literal
(Loc
, Ind
));
4610 Make_Raise_Constraint_Error
(Loc
,
4614 Convert_To
(Base_Type
(Etype
(Sub
)),
4615 Duplicate_Subexpr_Move_Checks
(Sub
)),
4617 Make_Attribute_Reference
(Loc
,
4619 Duplicate_Subexpr_Move_Checks
(A
, Name_Req
=> True),
4620 Attribute_Name
=> Name_Range
,
4621 Expressions
=> Num
)),
4622 Reason
=> CE_Index_Check_Failed
));
4628 end Generate_Index_Checks
;
4630 --------------------------
4631 -- Generate_Range_Check --
4632 --------------------------
4634 procedure Generate_Range_Check
4636 Target_Type
: Entity_Id
;
4637 Reason
: RT_Exception_Code
)
4639 Loc
: constant Source_Ptr
:= Sloc
(N
);
4640 Source_Type
: constant Entity_Id
:= Etype
(N
);
4641 Source_Base_Type
: constant Entity_Id
:= Base_Type
(Source_Type
);
4642 Target_Base_Type
: constant Entity_Id
:= Base_Type
(Target_Type
);
4645 -- First special case, if the source type is already within the range
4646 -- of the target type, then no check is needed (probably we should have
4647 -- stopped Do_Range_Check from being set in the first place, but better
4648 -- late than later in preventing junk code!
4650 -- We do NOT apply this if the source node is a literal, since in this
4651 -- case the literal has already been labeled as having the subtype of
4654 if In_Subrange_Of
(Source_Type
, Target_Type
)
4656 (Nkind
(N
) = N_Integer_Literal
4658 Nkind
(N
) = N_Real_Literal
4660 Nkind
(N
) = N_Character_Literal
4663 and then Ekind
(Entity
(N
)) = E_Enumeration_Literal
))
4668 -- We need a check, so force evaluation of the node, so that it does
4669 -- not get evaluated twice (once for the check, once for the actual
4670 -- reference). Such a double evaluation is always a potential source
4671 -- of inefficiency, and is functionally incorrect in the volatile case.
4673 if not Is_Entity_Name
(N
)
4674 or else Treat_As_Volatile
(Entity
(N
))
4676 Force_Evaluation
(N
);
4679 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4680 -- the same since in this case we can simply do a direct check of the
4681 -- value of N against the bounds of Target_Type.
4683 -- [constraint_error when N not in Target_Type]
4685 -- Note: this is by far the most common case, for example all cases of
4686 -- checks on the RHS of assignments are in this category, but not all
4687 -- cases are like this. Notably conversions can involve two types.
4689 if Source_Base_Type
= Target_Base_Type
then
4691 Make_Raise_Constraint_Error
(Loc
,
4694 Left_Opnd
=> Duplicate_Subexpr
(N
),
4695 Right_Opnd
=> New_Occurrence_Of
(Target_Type
, Loc
)),
4698 -- Next test for the case where the target type is within the bounds
4699 -- of the base type of the source type, since in this case we can
4700 -- simply convert these bounds to the base type of T to do the test.
4702 -- [constraint_error when N not in
4703 -- Source_Base_Type (Target_Type'First)
4705 -- Source_Base_Type(Target_Type'Last))]
4707 -- The conversions will always work and need no check
4709 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
4710 -- of converting from an enumeration value to an integer type, such as
4711 -- occurs for the case of generating a range check on Enum'Val(Exp)
4712 -- (which used to be handled by gigi). This is OK, since the conversion
4713 -- itself does not require a check.
4715 elsif In_Subrange_Of
(Target_Type
, Source_Base_Type
) then
4717 Make_Raise_Constraint_Error
(Loc
,
4720 Left_Opnd
=> Duplicate_Subexpr
(N
),
4725 Unchecked_Convert_To
(Source_Base_Type
,
4726 Make_Attribute_Reference
(Loc
,
4728 New_Occurrence_Of
(Target_Type
, Loc
),
4729 Attribute_Name
=> Name_First
)),
4732 Unchecked_Convert_To
(Source_Base_Type
,
4733 Make_Attribute_Reference
(Loc
,
4735 New_Occurrence_Of
(Target_Type
, Loc
),
4736 Attribute_Name
=> Name_Last
)))),
4739 -- Note that at this stage we now that the Target_Base_Type is not in
4740 -- the range of the Source_Base_Type (since even the Target_Type itself
4741 -- is not in this range). It could still be the case that Source_Type is
4742 -- in range of the target base type since we have not checked that case.
4744 -- If that is the case, we can freely convert the source to the target,
4745 -- and then test the target result against the bounds.
4747 elsif In_Subrange_Of
(Source_Type
, Target_Base_Type
) then
4749 -- We make a temporary to hold the value of the converted value
4750 -- (converted to the base type), and then we will do the test against
4753 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4754 -- [constraint_error when Tnn not in Target_Type]
4756 -- Then the conversion itself is replaced by an occurrence of Tnn
4759 Tnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', N
);
4762 Insert_Actions
(N
, New_List
(
4763 Make_Object_Declaration
(Loc
,
4764 Defining_Identifier
=> Tnn
,
4765 Object_Definition
=>
4766 New_Occurrence_Of
(Target_Base_Type
, Loc
),
4767 Constant_Present
=> True,
4769 Make_Type_Conversion
(Loc
,
4770 Subtype_Mark
=> New_Occurrence_Of
(Target_Base_Type
, Loc
),
4771 Expression
=> Duplicate_Subexpr
(N
))),
4773 Make_Raise_Constraint_Error
(Loc
,
4776 Left_Opnd
=> New_Occurrence_Of
(Tnn
, Loc
),
4777 Right_Opnd
=> New_Occurrence_Of
(Target_Type
, Loc
)),
4779 Reason
=> Reason
)));
4781 Rewrite
(N
, New_Occurrence_Of
(Tnn
, Loc
));
4783 -- Set the type of N, because the declaration for Tnn might not
4784 -- be analyzed yet, as is the case if N appears within a record
4785 -- declaration, as a discriminant constraint or expression.
4787 Set_Etype
(N
, Target_Base_Type
);
4790 -- At this stage, we know that we have two scalar types, which are
4791 -- directly convertible, and where neither scalar type has a base
4792 -- range that is in the range of the other scalar type.
4794 -- The only way this can happen is with a signed and unsigned type.
4795 -- So test for these two cases:
4798 -- Case of the source is unsigned and the target is signed
4800 if Is_Unsigned_Type
(Source_Base_Type
)
4801 and then not Is_Unsigned_Type
(Target_Base_Type
)
4803 -- If the source is unsigned and the target is signed, then we
4804 -- know that the source is not shorter than the target (otherwise
4805 -- the source base type would be in the target base type range).
4807 -- In other words, the unsigned type is either the same size as
4808 -- the target, or it is larger. It cannot be smaller.
4811 (Esize
(Source_Base_Type
) >= Esize
(Target_Base_Type
));
4813 -- We only need to check the low bound if the low bound of the
4814 -- target type is non-negative. If the low bound of the target
4815 -- type is negative, then we know that we will fit fine.
4817 -- If the high bound of the target type is negative, then we
4818 -- know we have a constraint error, since we can't possibly
4819 -- have a negative source.
4821 -- With these two checks out of the way, we can do the check
4822 -- using the source type safely
4824 -- This is definitely the most annoying case!
4826 -- [constraint_error
4827 -- when (Target_Type'First >= 0
4829 -- N < Source_Base_Type (Target_Type'First))
4830 -- or else Target_Type'Last < 0
4831 -- or else N > Source_Base_Type (Target_Type'Last)];
4833 -- We turn off all checks since we know that the conversions
4834 -- will work fine, given the guards for negative values.
4837 Make_Raise_Constraint_Error
(Loc
,
4843 Left_Opnd
=> Make_Op_Ge
(Loc
,
4845 Make_Attribute_Reference
(Loc
,
4847 New_Occurrence_Of
(Target_Type
, Loc
),
4848 Attribute_Name
=> Name_First
),
4849 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
4853 Left_Opnd
=> Duplicate_Subexpr
(N
),
4855 Convert_To
(Source_Base_Type
,
4856 Make_Attribute_Reference
(Loc
,
4858 New_Occurrence_Of
(Target_Type
, Loc
),
4859 Attribute_Name
=> Name_First
)))),
4864 Make_Attribute_Reference
(Loc
,
4865 Prefix
=> New_Occurrence_Of
(Target_Type
, Loc
),
4866 Attribute_Name
=> Name_Last
),
4867 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
))),
4871 Left_Opnd
=> Duplicate_Subexpr
(N
),
4873 Convert_To
(Source_Base_Type
,
4874 Make_Attribute_Reference
(Loc
,
4875 Prefix
=> New_Occurrence_Of
(Target_Type
, Loc
),
4876 Attribute_Name
=> Name_Last
)))),
4879 Suppress
=> All_Checks
);
4881 -- Only remaining possibility is that the source is signed and
4882 -- the target is unsigned.
4885 pragma Assert
(not Is_Unsigned_Type
(Source_Base_Type
)
4886 and then Is_Unsigned_Type
(Target_Base_Type
));
4888 -- If the source is signed and the target is unsigned, then we
4889 -- know that the target is not shorter than the source (otherwise
4890 -- the target base type would be in the source base type range).
4892 -- In other words, the unsigned type is either the same size as
4893 -- the target, or it is larger. It cannot be smaller.
4895 -- Clearly we have an error if the source value is negative since
4896 -- no unsigned type can have negative values. If the source type
4897 -- is non-negative, then the check can be done using the target
4900 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4902 -- [constraint_error
4903 -- when N < 0 or else Tnn not in Target_Type];
4905 -- We turn off all checks for the conversion of N to the target
4906 -- base type, since we generate the explicit check to ensure that
4907 -- the value is non-negative
4910 Tnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', N
);
4913 Insert_Actions
(N
, New_List
(
4914 Make_Object_Declaration
(Loc
,
4915 Defining_Identifier
=> Tnn
,
4916 Object_Definition
=>
4917 New_Occurrence_Of
(Target_Base_Type
, Loc
),
4918 Constant_Present
=> True,
4920 Make_Unchecked_Type_Conversion
(Loc
,
4922 New_Occurrence_Of
(Target_Base_Type
, Loc
),
4923 Expression
=> Duplicate_Subexpr
(N
))),
4925 Make_Raise_Constraint_Error
(Loc
,
4930 Left_Opnd
=> Duplicate_Subexpr
(N
),
4931 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
4935 Left_Opnd
=> New_Occurrence_Of
(Tnn
, Loc
),
4937 New_Occurrence_Of
(Target_Type
, Loc
))),
4940 Suppress
=> All_Checks
);
4942 -- Set the Etype explicitly, because Insert_Actions may have
4943 -- placed the declaration in the freeze list for an enclosing
4944 -- construct, and thus it is not analyzed yet.
4946 Set_Etype
(Tnn
, Target_Base_Type
);
4947 Rewrite
(N
, New_Occurrence_Of
(Tnn
, Loc
));
4951 end Generate_Range_Check
;
4957 function Get_Check_Id
(N
: Name_Id
) return Check_Id
is
4959 -- For standard check name, we can do a direct computation
4961 if N
in First_Check_Name
.. Last_Check_Name
then
4962 return Check_Id
(N
- (First_Check_Name
- 1));
4964 -- For non-standard names added by pragma Check_Name, search table
4967 for J
in All_Checks
+ 1 .. Check_Names
.Last
loop
4968 if Check_Names
.Table
(J
) = N
then
4974 -- No matching name found
4979 ---------------------
4980 -- Get_Discriminal --
4981 ---------------------
4983 function Get_Discriminal
(E
: Entity_Id
; Bound
: Node_Id
) return Node_Id
is
4984 Loc
: constant Source_Ptr
:= Sloc
(E
);
4989 -- The bound can be a bona fide parameter of a protected operation,
4990 -- rather than a prival encoded as an in-parameter.
4992 if No
(Discriminal_Link
(Entity
(Bound
))) then
4996 -- Climb the scope stack looking for an enclosing protected type. If
4997 -- we run out of scopes, return the bound itself.
5000 while Present
(Sc
) loop
5001 if Sc
= Standard_Standard
then
5004 elsif Ekind
(Sc
) = E_Protected_Type
then
5011 D
:= First_Discriminant
(Sc
);
5012 while Present
(D
) loop
5013 if Chars
(D
) = Chars
(Bound
) then
5014 return New_Occurrence_Of
(Discriminal
(D
), Loc
);
5017 Next_Discriminant
(D
);
5021 end Get_Discriminal
;
5023 ----------------------
5024 -- Get_Range_Checks --
5025 ----------------------
5027 function Get_Range_Checks
5029 Target_Typ
: Entity_Id
;
5030 Source_Typ
: Entity_Id
:= Empty
;
5031 Warn_Node
: Node_Id
:= Empty
) return Check_Result
5034 return Selected_Range_Checks
5035 (Ck_Node
, Target_Typ
, Source_Typ
, Warn_Node
);
5036 end Get_Range_Checks
;
5042 function Guard_Access
5045 Ck_Node
: Node_Id
) return Node_Id
5048 if Nkind
(Cond
) = N_Or_Else
then
5049 Set_Paren_Count
(Cond
, 1);
5052 if Nkind
(Ck_Node
) = N_Allocator
then
5059 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
5060 Right_Opnd
=> Make_Null
(Loc
)),
5061 Right_Opnd
=> Cond
);
5065 -----------------------------
5066 -- Index_Checks_Suppressed --
5067 -----------------------------
5069 function Index_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5071 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
5072 return Is_Check_Suppressed
(E
, Index_Check
);
5074 return Scope_Suppress
(Index_Check
);
5076 end Index_Checks_Suppressed
;
5082 procedure Initialize
is
5084 for J
in Determine_Range_Cache_N
'Range loop
5085 Determine_Range_Cache_N
(J
) := Empty
;
5090 for J
in Int
range 1 .. All_Checks
loop
5091 Check_Names
.Append
(Name_Id
(Int
(First_Check_Name
) + J
- 1));
5095 -------------------------
5096 -- Insert_Range_Checks --
5097 -------------------------
5099 procedure Insert_Range_Checks
5100 (Checks
: Check_Result
;
5102 Suppress_Typ
: Entity_Id
;
5103 Static_Sloc
: Source_Ptr
:= No_Location
;
5104 Flag_Node
: Node_Id
:= Empty
;
5105 Do_Before
: Boolean := False)
5107 Internal_Flag_Node
: Node_Id
:= Flag_Node
;
5108 Internal_Static_Sloc
: Source_Ptr
:= Static_Sloc
;
5110 Check_Node
: Node_Id
;
5111 Checks_On
: constant Boolean :=
5112 (not Index_Checks_Suppressed
(Suppress_Typ
))
5114 (not Range_Checks_Suppressed
(Suppress_Typ
));
5117 -- For now we just return if Checks_On is false, however this should be
5118 -- enhanced to check for an always True value in the condition and to
5119 -- generate a compilation warning???
5121 if not Expander_Active
or else not Checks_On
then
5125 if Static_Sloc
= No_Location
then
5126 Internal_Static_Sloc
:= Sloc
(Node
);
5129 if No
(Flag_Node
) then
5130 Internal_Flag_Node
:= Node
;
5133 for J
in 1 .. 2 loop
5134 exit when No
(Checks
(J
));
5136 if Nkind
(Checks
(J
)) = N_Raise_Constraint_Error
5137 and then Present
(Condition
(Checks
(J
)))
5139 if not Has_Dynamic_Range_Check
(Internal_Flag_Node
) then
5140 Check_Node
:= Checks
(J
);
5141 Mark_Rewrite_Insertion
(Check_Node
);
5144 Insert_Before_And_Analyze
(Node
, Check_Node
);
5146 Insert_After_And_Analyze
(Node
, Check_Node
);
5149 Set_Has_Dynamic_Range_Check
(Internal_Flag_Node
);
5154 Make_Raise_Constraint_Error
(Internal_Static_Sloc
,
5155 Reason
=> CE_Range_Check_Failed
);
5156 Mark_Rewrite_Insertion
(Check_Node
);
5159 Insert_Before_And_Analyze
(Node
, Check_Node
);
5161 Insert_After_And_Analyze
(Node
, Check_Node
);
5165 end Insert_Range_Checks
;
5167 ------------------------
5168 -- Insert_Valid_Check --
5169 ------------------------
5171 procedure Insert_Valid_Check
(Expr
: Node_Id
) is
5172 Loc
: constant Source_Ptr
:= Sloc
(Expr
);
5176 -- Do not insert if checks off, or if not checking validity or
5177 -- if expression is known to be valid
5179 if not Validity_Checks_On
5180 or else Range_Or_Validity_Checks_Suppressed
(Expr
)
5181 or else Expr_Known_Valid
(Expr
)
5186 -- If we have a checked conversion, then validity check applies to
5187 -- the expression inside the conversion, not the result, since if
5188 -- the expression inside is valid, then so is the conversion result.
5191 while Nkind
(Exp
) = N_Type_Conversion
loop
5192 Exp
:= Expression
(Exp
);
5195 -- We are about to insert the validity check for Exp. We save and
5196 -- reset the Do_Range_Check flag over this validity check, and then
5197 -- put it back for the final original reference (Exp may be rewritten).
5200 DRC
: constant Boolean := Do_Range_Check
(Exp
);
5203 Set_Do_Range_Check
(Exp
, False);
5205 -- Force evaluation to avoid multiple reads for atomic/volatile
5207 if Is_Entity_Name
(Exp
)
5208 and then Is_Volatile
(Entity
(Exp
))
5210 Force_Evaluation
(Exp
, Name_Req
=> True);
5213 -- Insert the validity check. Note that we do this with validity
5214 -- checks turned off, to avoid recursion, we do not want validity
5215 -- checks on the validity checking code itself!
5219 Make_Raise_Constraint_Error
(Loc
,
5223 Make_Attribute_Reference
(Loc
,
5225 Duplicate_Subexpr_No_Checks
(Exp
, Name_Req
=> True),
5226 Attribute_Name
=> Name_Valid
)),
5227 Reason
=> CE_Invalid_Data
),
5228 Suppress
=> Validity_Check
);
5230 -- If the expression is a reference to an element of a bit-packed
5231 -- array, then it is rewritten as a renaming declaration. If the
5232 -- expression is an actual in a call, it has not been expanded,
5233 -- waiting for the proper point at which to do it. The same happens
5234 -- with renamings, so that we have to force the expansion now. This
5235 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5238 if Is_Entity_Name
(Exp
)
5239 and then Nkind
(Parent
(Entity
(Exp
))) =
5240 N_Object_Renaming_Declaration
5243 Old_Exp
: constant Node_Id
:= Name
(Parent
(Entity
(Exp
)));
5245 if Nkind
(Old_Exp
) = N_Indexed_Component
5246 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Old_Exp
)))
5248 Expand_Packed_Element_Reference
(Old_Exp
);
5253 -- Put back the Do_Range_Check flag on the resulting (possibly
5254 -- rewritten) expression.
5256 -- Note: it might be thought that a validity check is not required
5257 -- when a range check is present, but that's not the case, because
5258 -- the back end is allowed to assume for the range check that the
5259 -- operand is within its declared range (an assumption that validity
5260 -- checking is all about NOT assuming!)
5262 -- Note: no need to worry about Possible_Local_Raise here, it will
5263 -- already have been called if original node has Do_Range_Check set.
5265 Set_Do_Range_Check
(Exp
, DRC
);
5267 end Insert_Valid_Check
;
5269 ----------------------------------
5270 -- Install_Null_Excluding_Check --
5271 ----------------------------------
5273 procedure Install_Null_Excluding_Check
(N
: Node_Id
) is
5274 Loc
: constant Source_Ptr
:= Sloc
(Parent
(N
));
5275 Typ
: constant Entity_Id
:= Etype
(N
);
5277 function Safe_To_Capture_In_Parameter_Value
return Boolean;
5278 -- Determines if it is safe to capture Known_Non_Null status for an
5279 -- the entity referenced by node N. The caller ensures that N is indeed
5280 -- an entity name. It is safe to capture the non-null status for an IN
5281 -- parameter when the reference occurs within a declaration that is sure
5282 -- to be executed as part of the declarative region.
5284 procedure Mark_Non_Null
;
5285 -- After installation of check, if the node in question is an entity
5286 -- name, then mark this entity as non-null if possible.
5288 function Safe_To_Capture_In_Parameter_Value
return Boolean is
5289 E
: constant Entity_Id
:= Entity
(N
);
5290 S
: constant Entity_Id
:= Current_Scope
;
5294 if Ekind
(E
) /= E_In_Parameter
then
5298 -- Two initial context checks. We must be inside a subprogram body
5299 -- with declarations and reference must not appear in nested scopes.
5301 if (Ekind
(S
) /= E_Function
and then Ekind
(S
) /= E_Procedure
)
5302 or else Scope
(E
) /= S
5307 S_Par
:= Parent
(Parent
(S
));
5309 if Nkind
(S_Par
) /= N_Subprogram_Body
5310 or else No
(Declarations
(S_Par
))
5320 -- Retrieve the declaration node of N (if any). Note that N
5321 -- may be a part of a complex initialization expression.
5325 while Present
(P
) loop
5327 -- If we have a short circuit form, and we are within the right
5328 -- hand expression, we return false, since the right hand side
5329 -- is not guaranteed to be elaborated.
5331 if Nkind
(P
) in N_Short_Circuit
5332 and then N
= Right_Opnd
(P
)
5337 -- Similarly, if we are in a conditional expression and not
5338 -- part of the condition, then we return False, since neither
5339 -- the THEN or ELSE expressions will always be elaborated.
5341 if Nkind
(P
) = N_Conditional_Expression
5342 and then N
/= First
(Expressions
(P
))
5347 -- If we are in a case expression, and not part of the
5348 -- expression, then we return False, since a particular
5349 -- branch may not always be elaborated
5351 if Nkind
(P
) = N_Case_Expression
5352 and then N
/= Expression
(P
)
5357 -- While traversing the parent chain, we find that N
5358 -- belongs to a statement, thus it may never appear in
5359 -- a declarative region.
5361 if Nkind
(P
) in N_Statement_Other_Than_Procedure_Call
5362 or else Nkind
(P
) = N_Procedure_Call_Statement
5367 -- If we are at a declaration, record it and exit
5369 if Nkind
(P
) in N_Declaration
5370 and then Nkind
(P
) not in N_Subprogram_Specification
5383 return List_Containing
(N_Decl
) = Declarations
(S_Par
);
5385 end Safe_To_Capture_In_Parameter_Value
;
5391 procedure Mark_Non_Null
is
5393 -- Only case of interest is if node N is an entity name
5395 if Is_Entity_Name
(N
) then
5397 -- For sure, we want to clear an indication that this is known to
5398 -- be null, since if we get past this check, it definitely is not!
5400 Set_Is_Known_Null
(Entity
(N
), False);
5402 -- We can mark the entity as known to be non-null if either it is
5403 -- safe to capture the value, or in the case of an IN parameter,
5404 -- which is a constant, if the check we just installed is in the
5405 -- declarative region of the subprogram body. In this latter case,
5406 -- a check is decisive for the rest of the body if the expression
5407 -- is sure to be elaborated, since we know we have to elaborate
5408 -- all declarations before executing the body.
5410 -- Couldn't this always be part of Safe_To_Capture_Value ???
5412 if Safe_To_Capture_Value
(N
, Entity
(N
))
5413 or else Safe_To_Capture_In_Parameter_Value
5415 Set_Is_Known_Non_Null
(Entity
(N
));
5420 -- Start of processing for Install_Null_Excluding_Check
5423 pragma Assert
(Is_Access_Type
(Typ
));
5425 -- No check inside a generic (why not???)
5427 if Inside_A_Generic
then
5431 -- No check needed if known to be non-null
5433 if Known_Non_Null
(N
) then
5437 -- If known to be null, here is where we generate a compile time check
5439 if Known_Null
(N
) then
5441 -- Avoid generating warning message inside init procs
5443 if not Inside_Init_Proc
then
5444 Apply_Compile_Time_Constraint_Error
5446 "null value not allowed here?",
5447 CE_Access_Check_Failed
);
5450 Make_Raise_Constraint_Error
(Loc
,
5451 Reason
=> CE_Access_Check_Failed
));
5458 -- If entity is never assigned, for sure a warning is appropriate
5460 if Is_Entity_Name
(N
) then
5461 Check_Unset_Reference
(N
);
5464 -- No check needed if checks are suppressed on the range. Note that we
5465 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5466 -- so, since the program is erroneous, but we don't like to casually
5467 -- propagate such conclusions from erroneosity).
5469 if Access_Checks_Suppressed
(Typ
) then
5473 -- No check needed for access to concurrent record types generated by
5474 -- the expander. This is not just an optimization (though it does indeed
5475 -- remove junk checks). It also avoids generation of junk warnings.
5477 if Nkind
(N
) in N_Has_Chars
5478 and then Chars
(N
) = Name_uObject
5479 and then Is_Concurrent_Record_Type
5480 (Directly_Designated_Type
(Etype
(N
)))
5485 -- Otherwise install access check
5488 Make_Raise_Constraint_Error
(Loc
,
5491 Left_Opnd
=> Duplicate_Subexpr_Move_Checks
(N
),
5492 Right_Opnd
=> Make_Null
(Loc
)),
5493 Reason
=> CE_Access_Check_Failed
));
5496 end Install_Null_Excluding_Check
;
5498 --------------------------
5499 -- Install_Static_Check --
5500 --------------------------
5502 procedure Install_Static_Check
(R_Cno
: Node_Id
; Loc
: Source_Ptr
) is
5503 Stat
: constant Boolean := Is_Static_Expression
(R_Cno
);
5504 Typ
: constant Entity_Id
:= Etype
(R_Cno
);
5508 Make_Raise_Constraint_Error
(Loc
,
5509 Reason
=> CE_Range_Check_Failed
));
5510 Set_Analyzed
(R_Cno
);
5511 Set_Etype
(R_Cno
, Typ
);
5512 Set_Raises_Constraint_Error
(R_Cno
);
5513 Set_Is_Static_Expression
(R_Cno
, Stat
);
5515 -- Now deal with possible local raise handling
5517 Possible_Local_Raise
(R_Cno
, Standard_Constraint_Error
);
5518 end Install_Static_Check
;
5520 ---------------------
5521 -- Kill_All_Checks --
5522 ---------------------
5524 procedure Kill_All_Checks
is
5526 if Debug_Flag_CC
then
5527 w
("Kill_All_Checks");
5530 -- We reset the number of saved checks to zero, and also modify all
5531 -- stack entries for statement ranges to indicate that the number of
5532 -- checks at each level is now zero.
5534 Num_Saved_Checks
:= 0;
5536 -- Note: the Int'Min here avoids any possibility of J being out of
5537 -- range when called from e.g. Conditional_Statements_Begin.
5539 for J
in 1 .. Int
'Min (Saved_Checks_TOS
, Saved_Checks_Stack
'Last) loop
5540 Saved_Checks_Stack
(J
) := 0;
5542 end Kill_All_Checks
;
5548 procedure Kill_Checks
(V
: Entity_Id
) is
5550 if Debug_Flag_CC
then
5551 w
("Kill_Checks for entity", Int
(V
));
5554 for J
in 1 .. Num_Saved_Checks
loop
5555 if Saved_Checks
(J
).Entity
= V
then
5556 if Debug_Flag_CC
then
5557 w
(" Checks killed for saved check ", J
);
5560 Saved_Checks
(J
).Killed
:= True;
5565 ------------------------------
5566 -- Length_Checks_Suppressed --
5567 ------------------------------
5569 function Length_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5571 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
5572 return Is_Check_Suppressed
(E
, Length_Check
);
5574 return Scope_Suppress
(Length_Check
);
5576 end Length_Checks_Suppressed
;
5578 --------------------------------
5579 -- Overflow_Checks_Suppressed --
5580 --------------------------------
5582 function Overflow_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5584 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
5585 return Is_Check_Suppressed
(E
, Overflow_Check
);
5587 return Scope_Suppress
(Overflow_Check
);
5589 end Overflow_Checks_Suppressed
;
5591 -----------------------------
5592 -- Range_Checks_Suppressed --
5593 -----------------------------
5595 function Range_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5599 -- Note: for now we always suppress range checks on Vax float types,
5600 -- since Gigi does not know how to generate these checks.
5602 if Vax_Float
(E
) then
5604 elsif Kill_Range_Checks
(E
) then
5606 elsif Checks_May_Be_Suppressed
(E
) then
5607 return Is_Check_Suppressed
(E
, Range_Check
);
5611 return Scope_Suppress
(Range_Check
);
5612 end Range_Checks_Suppressed
;
5614 -----------------------------------------
5615 -- Range_Or_Validity_Checks_Suppressed --
5616 -----------------------------------------
5618 -- Note: the coding would be simpler here if we simply made appropriate
5619 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5620 -- duplicated checks which we prefer to avoid.
5622 function Range_Or_Validity_Checks_Suppressed
5623 (Expr
: Node_Id
) return Boolean
5626 -- Immediate return if scope checks suppressed for either check
5628 if Scope_Suppress
(Range_Check
) or Scope_Suppress
(Validity_Check
) then
5632 -- If no expression, that's odd, decide that checks are suppressed,
5633 -- since we don't want anyone trying to do checks in this case, which
5634 -- is most likely the result of some other error.
5640 -- Expression is present, so perform suppress checks on type
5643 Typ
: constant Entity_Id
:= Etype
(Expr
);
5645 if Vax_Float
(Typ
) then
5647 elsif Checks_May_Be_Suppressed
(Typ
)
5648 and then (Is_Check_Suppressed
(Typ
, Range_Check
)
5650 Is_Check_Suppressed
(Typ
, Validity_Check
))
5656 -- If expression is an entity name, perform checks on this entity
5658 if Is_Entity_Name
(Expr
) then
5660 Ent
: constant Entity_Id
:= Entity
(Expr
);
5662 if Checks_May_Be_Suppressed
(Ent
) then
5663 return Is_Check_Suppressed
(Ent
, Range_Check
)
5664 or else Is_Check_Suppressed
(Ent
, Validity_Check
);
5669 -- If we fall through, no checks suppressed
5672 end Range_Or_Validity_Checks_Suppressed
;
5678 procedure Remove_Checks
(Expr
: Node_Id
) is
5679 function Process
(N
: Node_Id
) return Traverse_Result
;
5680 -- Process a single node during the traversal
5682 procedure Traverse
is new Traverse_Proc
(Process
);
5683 -- The traversal procedure itself
5689 function Process
(N
: Node_Id
) return Traverse_Result
is
5691 if Nkind
(N
) not in N_Subexpr
then
5695 Set_Do_Range_Check
(N
, False);
5699 Traverse
(Left_Opnd
(N
));
5702 when N_Attribute_Reference
=>
5703 Set_Do_Overflow_Check
(N
, False);
5705 when N_Function_Call
=>
5706 Set_Do_Tag_Check
(N
, False);
5709 Set_Do_Overflow_Check
(N
, False);
5713 Set_Do_Division_Check
(N
, False);
5716 Set_Do_Length_Check
(N
, False);
5719 Set_Do_Division_Check
(N
, False);
5722 Set_Do_Length_Check
(N
, False);
5725 Set_Do_Division_Check
(N
, False);
5728 Set_Do_Length_Check
(N
, False);
5735 Traverse
(Left_Opnd
(N
));
5738 when N_Selected_Component
=>
5739 Set_Do_Discriminant_Check
(N
, False);
5741 when N_Type_Conversion
=>
5742 Set_Do_Length_Check
(N
, False);
5743 Set_Do_Tag_Check
(N
, False);
5744 Set_Do_Overflow_Check
(N
, False);
5753 -- Start of processing for Remove_Checks
5759 ----------------------------
5760 -- Selected_Length_Checks --
5761 ----------------------------
5763 function Selected_Length_Checks
5765 Target_Typ
: Entity_Id
;
5766 Source_Typ
: Entity_Id
;
5767 Warn_Node
: Node_Id
) return Check_Result
5769 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
5772 Expr_Actual
: Node_Id
;
5774 Cond
: Node_Id
:= Empty
;
5775 Do_Access
: Boolean := False;
5776 Wnode
: Node_Id
:= Warn_Node
;
5777 Ret_Result
: Check_Result
:= (Empty
, Empty
);
5778 Num_Checks
: Natural := 0;
5780 procedure Add_Check
(N
: Node_Id
);
5781 -- Adds the action given to Ret_Result if N is non-Empty
5783 function Get_E_Length
(E
: Entity_Id
; Indx
: Nat
) return Node_Id
;
5784 function Get_N_Length
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
5785 -- Comments required ???
5787 function Same_Bounds
(L
: Node_Id
; R
: Node_Id
) return Boolean;
5788 -- True for equal literals and for nodes that denote the same constant
5789 -- entity, even if its value is not a static constant. This includes the
5790 -- case of a discriminal reference within an init proc. Removes some
5791 -- obviously superfluous checks.
5793 function Length_E_Cond
5794 (Exptyp
: Entity_Id
;
5796 Indx
: Nat
) return Node_Id
;
5797 -- Returns expression to compute:
5798 -- Typ'Length /= Exptyp'Length
5800 function Length_N_Cond
5803 Indx
: Nat
) return Node_Id
;
5804 -- Returns expression to compute:
5805 -- Typ'Length /= Expr'Length
5811 procedure Add_Check
(N
: Node_Id
) is
5815 -- For now, ignore attempt to place more than 2 checks ???
5817 if Num_Checks
= 2 then
5821 pragma Assert
(Num_Checks
<= 1);
5822 Num_Checks
:= Num_Checks
+ 1;
5823 Ret_Result
(Num_Checks
) := N
;
5831 function Get_E_Length
(E
: Entity_Id
; Indx
: Nat
) return Node_Id
is
5832 SE
: constant Entity_Id
:= Scope
(E
);
5834 E1
: Entity_Id
:= E
;
5837 if Ekind
(Scope
(E
)) = E_Record_Type
5838 and then Has_Discriminants
(Scope
(E
))
5840 N
:= Build_Discriminal_Subtype_Of_Component
(E
);
5843 Insert_Action
(Ck_Node
, N
);
5844 E1
:= Defining_Identifier
(N
);
5848 if Ekind
(E1
) = E_String_Literal_Subtype
then
5850 Make_Integer_Literal
(Loc
,
5851 Intval
=> String_Literal_Length
(E1
));
5853 elsif SE
/= Standard_Standard
5854 and then Ekind
(Scope
(SE
)) = E_Protected_Type
5855 and then Has_Discriminants
(Scope
(SE
))
5856 and then Has_Completion
(Scope
(SE
))
5857 and then not Inside_Init_Proc
5859 -- If the type whose length is needed is a private component
5860 -- constrained by a discriminant, we must expand the 'Length
5861 -- attribute into an explicit computation, using the discriminal
5862 -- of the current protected operation. This is because the actual
5863 -- type of the prival is constructed after the protected opera-
5864 -- tion has been fully expanded.
5867 Indx_Type
: Node_Id
;
5870 Do_Expand
: Boolean := False;
5873 Indx_Type
:= First_Index
(E
);
5875 for J
in 1 .. Indx
- 1 loop
5876 Next_Index
(Indx_Type
);
5879 Get_Index_Bounds
(Indx_Type
, Lo
, Hi
);
5881 if Nkind
(Lo
) = N_Identifier
5882 and then Ekind
(Entity
(Lo
)) = E_In_Parameter
5884 Lo
:= Get_Discriminal
(E
, Lo
);
5888 if Nkind
(Hi
) = N_Identifier
5889 and then Ekind
(Entity
(Hi
)) = E_In_Parameter
5891 Hi
:= Get_Discriminal
(E
, Hi
);
5896 if not Is_Entity_Name
(Lo
) then
5897 Lo
:= Duplicate_Subexpr_No_Checks
(Lo
);
5900 if not Is_Entity_Name
(Hi
) then
5901 Lo
:= Duplicate_Subexpr_No_Checks
(Hi
);
5907 Make_Op_Subtract
(Loc
,
5911 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1));
5916 Make_Attribute_Reference
(Loc
,
5917 Attribute_Name
=> Name_Length
,
5919 New_Occurrence_Of
(E1
, Loc
));
5922 Set_Expressions
(N
, New_List
(
5923 Make_Integer_Literal
(Loc
, Indx
)));
5932 Make_Attribute_Reference
(Loc
,
5933 Attribute_Name
=> Name_Length
,
5935 New_Occurrence_Of
(E1
, Loc
));
5938 Set_Expressions
(N
, New_List
(
5939 Make_Integer_Literal
(Loc
, Indx
)));
5950 function Get_N_Length
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
5953 Make_Attribute_Reference
(Loc
,
5954 Attribute_Name
=> Name_Length
,
5956 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
5957 Expressions
=> New_List
(
5958 Make_Integer_Literal
(Loc
, Indx
)));
5965 function Length_E_Cond
5966 (Exptyp
: Entity_Id
;
5968 Indx
: Nat
) return Node_Id
5973 Left_Opnd
=> Get_E_Length
(Typ
, Indx
),
5974 Right_Opnd
=> Get_E_Length
(Exptyp
, Indx
));
5981 function Length_N_Cond
5984 Indx
: Nat
) return Node_Id
5989 Left_Opnd
=> Get_E_Length
(Typ
, Indx
),
5990 Right_Opnd
=> Get_N_Length
(Expr
, Indx
));
5997 function Same_Bounds
(L
: Node_Id
; R
: Node_Id
) return Boolean is
6000 (Nkind
(L
) = N_Integer_Literal
6001 and then Nkind
(R
) = N_Integer_Literal
6002 and then Intval
(L
) = Intval
(R
))
6006 and then Ekind
(Entity
(L
)) = E_Constant
6007 and then ((Is_Entity_Name
(R
)
6008 and then Entity
(L
) = Entity
(R
))
6010 (Nkind
(R
) = N_Type_Conversion
6011 and then Is_Entity_Name
(Expression
(R
))
6012 and then Entity
(L
) = Entity
(Expression
(R
)))))
6016 and then Ekind
(Entity
(R
)) = E_Constant
6017 and then Nkind
(L
) = N_Type_Conversion
6018 and then Is_Entity_Name
(Expression
(L
))
6019 and then Entity
(R
) = Entity
(Expression
(L
)))
6023 and then Is_Entity_Name
(R
)
6024 and then Entity
(L
) = Entity
(R
)
6025 and then Ekind
(Entity
(L
)) = E_In_Parameter
6026 and then Inside_Init_Proc
);
6029 -- Start of processing for Selected_Length_Checks
6032 if not Expander_Active
then
6036 if Target_Typ
= Any_Type
6037 or else Target_Typ
= Any_Composite
6038 or else Raises_Constraint_Error
(Ck_Node
)
6047 T_Typ
:= Target_Typ
;
6049 if No
(Source_Typ
) then
6050 S_Typ
:= Etype
(Ck_Node
);
6052 S_Typ
:= Source_Typ
;
6055 if S_Typ
= Any_Type
or else S_Typ
= Any_Composite
then
6059 if Is_Access_Type
(T_Typ
) and then Is_Access_Type
(S_Typ
) then
6060 S_Typ
:= Designated_Type
(S_Typ
);
6061 T_Typ
:= Designated_Type
(T_Typ
);
6064 -- A simple optimization for the null case
6066 if Known_Null
(Ck_Node
) then
6071 if Is_Array_Type
(T_Typ
) and then Is_Array_Type
(S_Typ
) then
6072 if Is_Constrained
(T_Typ
) then
6074 -- The checking code to be generated will freeze the
6075 -- corresponding array type. However, we must freeze the
6076 -- type now, so that the freeze node does not appear within
6077 -- the generated conditional expression, but ahead of it.
6079 Freeze_Before
(Ck_Node
, T_Typ
);
6081 Expr_Actual
:= Get_Referenced_Object
(Ck_Node
);
6082 Exptyp
:= Get_Actual_Subtype
(Ck_Node
);
6084 if Is_Access_Type
(Exptyp
) then
6085 Exptyp
:= Designated_Type
(Exptyp
);
6088 -- String_Literal case. This needs to be handled specially be-
6089 -- cause no index types are available for string literals. The
6090 -- condition is simply:
6092 -- T_Typ'Length = string-literal-length
6094 if Nkind
(Expr_Actual
) = N_String_Literal
6095 and then Ekind
(Etype
(Expr_Actual
)) = E_String_Literal_Subtype
6099 Left_Opnd
=> Get_E_Length
(T_Typ
, 1),
6101 Make_Integer_Literal
(Loc
,
6103 String_Literal_Length
(Etype
(Expr_Actual
))));
6105 -- General array case. Here we have a usable actual subtype for
6106 -- the expression, and the condition is built from the two types
6109 -- T_Typ'Length /= Exptyp'Length or else
6110 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
6111 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
6114 elsif Is_Constrained
(Exptyp
) then
6116 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
6129 -- At the library level, we need to ensure that the type of
6130 -- the object is elaborated before the check itself is
6131 -- emitted. This is only done if the object is in the
6132 -- current compilation unit, otherwise the type is frozen
6133 -- and elaborated in its unit.
6135 if Is_Itype
(Exptyp
)
6137 Ekind
(Cunit_Entity
(Current_Sem_Unit
)) = E_Package
6139 not In_Package_Body
(Cunit_Entity
(Current_Sem_Unit
))
6140 and then In_Open_Scopes
(Scope
(Exptyp
))
6142 Ref_Node
:= Make_Itype_Reference
(Sloc
(Ck_Node
));
6143 Set_Itype
(Ref_Node
, Exptyp
);
6144 Insert_Action
(Ck_Node
, Ref_Node
);
6147 L_Index
:= First_Index
(T_Typ
);
6148 R_Index
:= First_Index
(Exptyp
);
6150 for Indx
in 1 .. Ndims
loop
6151 if not (Nkind
(L_Index
) = N_Raise_Constraint_Error
6153 Nkind
(R_Index
) = N_Raise_Constraint_Error
)
6155 Get_Index_Bounds
(L_Index
, L_Low
, L_High
);
6156 Get_Index_Bounds
(R_Index
, R_Low
, R_High
);
6158 -- Deal with compile time length check. Note that we
6159 -- skip this in the access case, because the access
6160 -- value may be null, so we cannot know statically.
6163 and then Compile_Time_Known_Value
(L_Low
)
6164 and then Compile_Time_Known_Value
(L_High
)
6165 and then Compile_Time_Known_Value
(R_Low
)
6166 and then Compile_Time_Known_Value
(R_High
)
6168 if Expr_Value
(L_High
) >= Expr_Value
(L_Low
) then
6169 L_Length
:= Expr_Value
(L_High
) -
6170 Expr_Value
(L_Low
) + 1;
6172 L_Length
:= UI_From_Int
(0);
6175 if Expr_Value
(R_High
) >= Expr_Value
(R_Low
) then
6176 R_Length
:= Expr_Value
(R_High
) -
6177 Expr_Value
(R_Low
) + 1;
6179 R_Length
:= UI_From_Int
(0);
6182 if L_Length
> R_Length
then
6184 (Compile_Time_Constraint_Error
6185 (Wnode
, "too few elements for}?", T_Typ
));
6187 elsif L_Length
< R_Length
then
6189 (Compile_Time_Constraint_Error
6190 (Wnode
, "too many elements for}?", T_Typ
));
6193 -- The comparison for an individual index subtype
6194 -- is omitted if the corresponding index subtypes
6195 -- statically match, since the result is known to
6196 -- be true. Note that this test is worth while even
6197 -- though we do static evaluation, because non-static
6198 -- subtypes can statically match.
6201 Subtypes_Statically_Match
6202 (Etype
(L_Index
), Etype
(R_Index
))
6205 (Same_Bounds
(L_Low
, R_Low
)
6206 and then Same_Bounds
(L_High
, R_High
))
6209 (Cond
, Length_E_Cond
(Exptyp
, T_Typ
, Indx
));
6218 -- Handle cases where we do not get a usable actual subtype that
6219 -- is constrained. This happens for example in the function call
6220 -- and explicit dereference cases. In these cases, we have to get
6221 -- the length or range from the expression itself, making sure we
6222 -- do not evaluate it more than once.
6224 -- Here Ck_Node is the original expression, or more properly the
6225 -- result of applying Duplicate_Expr to the original tree, forcing
6226 -- the result to be a name.
6230 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
6233 -- Build the condition for the explicit dereference case
6235 for Indx
in 1 .. Ndims
loop
6237 (Cond
, Length_N_Cond
(Ck_Node
, T_Typ
, Indx
));
6244 -- Construct the test and insert into the tree
6246 if Present
(Cond
) then
6248 Cond
:= Guard_Access
(Cond
, Loc
, Ck_Node
);
6252 (Make_Raise_Constraint_Error
(Loc
,
6254 Reason
=> CE_Length_Check_Failed
));
6258 end Selected_Length_Checks
;
6260 ---------------------------
6261 -- Selected_Range_Checks --
6262 ---------------------------
6264 function Selected_Range_Checks
6266 Target_Typ
: Entity_Id
;
6267 Source_Typ
: Entity_Id
;
6268 Warn_Node
: Node_Id
) return Check_Result
6270 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
6273 Expr_Actual
: Node_Id
;
6275 Cond
: Node_Id
:= Empty
;
6276 Do_Access
: Boolean := False;
6277 Wnode
: Node_Id
:= Warn_Node
;
6278 Ret_Result
: Check_Result
:= (Empty
, Empty
);
6279 Num_Checks
: Integer := 0;
6281 procedure Add_Check
(N
: Node_Id
);
6282 -- Adds the action given to Ret_Result if N is non-Empty
6284 function Discrete_Range_Cond
6286 Typ
: Entity_Id
) return Node_Id
;
6287 -- Returns expression to compute:
6288 -- Low_Bound (Expr) < Typ'First
6290 -- High_Bound (Expr) > Typ'Last
6292 function Discrete_Expr_Cond
6294 Typ
: Entity_Id
) return Node_Id
;
6295 -- Returns expression to compute:
6300 function Get_E_First_Or_Last
6304 Nam
: Name_Id
) return Node_Id
;
6305 -- Returns an attribute reference
6306 -- E'First or E'Last
6307 -- with a source location of Loc.
6309 -- Nam is Name_First or Name_Last, according to which attribute is
6310 -- desired. If Indx is non-zero, it is passed as a literal in the
6311 -- Expressions of the attribute reference (identifying the desired
6312 -- array dimension).
6314 function Get_N_First
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
6315 function Get_N_Last
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
6316 -- Returns expression to compute:
6317 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6319 function Range_E_Cond
6320 (Exptyp
: Entity_Id
;
6324 -- Returns expression to compute:
6325 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6327 function Range_Equal_E_Cond
6328 (Exptyp
: Entity_Id
;
6330 Indx
: Nat
) return Node_Id
;
6331 -- Returns expression to compute:
6332 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6334 function Range_N_Cond
6337 Indx
: Nat
) return Node_Id
;
6338 -- Return expression to compute:
6339 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6345 procedure Add_Check
(N
: Node_Id
) is
6349 -- For now, ignore attempt to place more than 2 checks ???
6351 if Num_Checks
= 2 then
6355 pragma Assert
(Num_Checks
<= 1);
6356 Num_Checks
:= Num_Checks
+ 1;
6357 Ret_Result
(Num_Checks
) := N
;
6361 -------------------------
6362 -- Discrete_Expr_Cond --
6363 -------------------------
6365 function Discrete_Expr_Cond
6367 Typ
: Entity_Id
) return Node_Id
6375 Convert_To
(Base_Type
(Typ
),
6376 Duplicate_Subexpr_No_Checks
(Expr
)),
6378 Convert_To
(Base_Type
(Typ
),
6379 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_First
))),
6384 Convert_To
(Base_Type
(Typ
),
6385 Duplicate_Subexpr_No_Checks
(Expr
)),
6389 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_Last
))));
6390 end Discrete_Expr_Cond
;
6392 -------------------------
6393 -- Discrete_Range_Cond --
6394 -------------------------
6396 function Discrete_Range_Cond
6398 Typ
: Entity_Id
) return Node_Id
6400 LB
: Node_Id
:= Low_Bound
(Expr
);
6401 HB
: Node_Id
:= High_Bound
(Expr
);
6403 Left_Opnd
: Node_Id
;
6404 Right_Opnd
: Node_Id
;
6407 if Nkind
(LB
) = N_Identifier
6408 and then Ekind
(Entity
(LB
)) = E_Discriminant
6410 LB
:= New_Occurrence_Of
(Discriminal
(Entity
(LB
)), Loc
);
6413 if Nkind
(HB
) = N_Identifier
6414 and then Ekind
(Entity
(HB
)) = E_Discriminant
6416 HB
:= New_Occurrence_Of
(Discriminal
(Entity
(HB
)), Loc
);
6423 (Base_Type
(Typ
), Duplicate_Subexpr_No_Checks
(LB
)),
6428 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_First
)));
6430 if Base_Type
(Typ
) = Typ
then
6433 elsif Compile_Time_Known_Value
(High_Bound
(Scalar_Range
(Typ
)))
6435 Compile_Time_Known_Value
(High_Bound
(Scalar_Range
6438 if Is_Floating_Point_Type
(Typ
) then
6439 if Expr_Value_R
(High_Bound
(Scalar_Range
(Typ
))) =
6440 Expr_Value_R
(High_Bound
(Scalar_Range
(Base_Type
(Typ
))))
6446 if Expr_Value
(High_Bound
(Scalar_Range
(Typ
))) =
6447 Expr_Value
(High_Bound
(Scalar_Range
(Base_Type
(Typ
))))
6458 (Base_Type
(Typ
), Duplicate_Subexpr_No_Checks
(HB
)),
6463 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_Last
)));
6465 return Make_Or_Else
(Loc
, Left_Opnd
, Right_Opnd
);
6466 end Discrete_Range_Cond
;
6468 -------------------------
6469 -- Get_E_First_Or_Last --
6470 -------------------------
6472 function Get_E_First_Or_Last
6476 Nam
: Name_Id
) return Node_Id
6481 Exprs
:= New_List
(Make_Integer_Literal
(Loc
, UI_From_Int
(Indx
)));
6486 return Make_Attribute_Reference
(Loc
,
6487 Prefix
=> New_Occurrence_Of
(E
, Loc
),
6488 Attribute_Name
=> Nam
,
6489 Expressions
=> Exprs
);
6490 end Get_E_First_Or_Last
;
6496 function Get_N_First
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
6499 Make_Attribute_Reference
(Loc
,
6500 Attribute_Name
=> Name_First
,
6502 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
6503 Expressions
=> New_List
(
6504 Make_Integer_Literal
(Loc
, Indx
)));
6511 function Get_N_Last
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
6514 Make_Attribute_Reference
(Loc
,
6515 Attribute_Name
=> Name_Last
,
6517 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
6518 Expressions
=> New_List
(
6519 Make_Integer_Literal
(Loc
, Indx
)));
6526 function Range_E_Cond
6527 (Exptyp
: Entity_Id
;
6529 Indx
: Nat
) return Node_Id
6537 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_First
),
6539 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
6544 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_Last
),
6546 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
6549 ------------------------
6550 -- Range_Equal_E_Cond --
6551 ------------------------
6553 function Range_Equal_E_Cond
6554 (Exptyp
: Entity_Id
;
6556 Indx
: Nat
) return Node_Id
6564 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_First
),
6566 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
6571 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_Last
),
6573 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
6574 end Range_Equal_E_Cond
;
6580 function Range_N_Cond
6583 Indx
: Nat
) return Node_Id
6591 Get_N_First
(Expr
, Indx
),
6593 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
6598 Get_N_Last
(Expr
, Indx
),
6600 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
6603 -- Start of processing for Selected_Range_Checks
6606 if not Expander_Active
then
6610 if Target_Typ
= Any_Type
6611 or else Target_Typ
= Any_Composite
6612 or else Raises_Constraint_Error
(Ck_Node
)
6621 T_Typ
:= Target_Typ
;
6623 if No
(Source_Typ
) then
6624 S_Typ
:= Etype
(Ck_Node
);
6626 S_Typ
:= Source_Typ
;
6629 if S_Typ
= Any_Type
or else S_Typ
= Any_Composite
then
6633 -- The order of evaluating T_Typ before S_Typ seems to be critical
6634 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6635 -- in, and since Node can be an N_Range node, it might be invalid.
6636 -- Should there be an assert check somewhere for taking the Etype of
6637 -- an N_Range node ???
6639 if Is_Access_Type
(T_Typ
) and then Is_Access_Type
(S_Typ
) then
6640 S_Typ
:= Designated_Type
(S_Typ
);
6641 T_Typ
:= Designated_Type
(T_Typ
);
6644 -- A simple optimization for the null case
6646 if Known_Null
(Ck_Node
) then
6651 -- For an N_Range Node, check for a null range and then if not
6652 -- null generate a range check action.
6654 if Nkind
(Ck_Node
) = N_Range
then
6656 -- There's no point in checking a range against itself
6658 if Ck_Node
= Scalar_Range
(T_Typ
) then
6663 T_LB
: constant Node_Id
:= Type_Low_Bound
(T_Typ
);
6664 T_HB
: constant Node_Id
:= Type_High_Bound
(T_Typ
);
6665 Known_T_LB
: constant Boolean := Compile_Time_Known_Value
(T_LB
);
6666 Known_T_HB
: constant Boolean := Compile_Time_Known_Value
(T_HB
);
6668 LB
: Node_Id
:= Low_Bound
(Ck_Node
);
6669 HB
: Node_Id
:= High_Bound
(Ck_Node
);
6673 Null_Range
: Boolean;
6674 Out_Of_Range_L
: Boolean;
6675 Out_Of_Range_H
: Boolean;
6678 -- Compute what is known at compile time
6680 if Known_T_LB
and Known_T_HB
then
6681 if Compile_Time_Known_Value
(LB
) then
6684 -- There's no point in checking that a bound is within its
6685 -- own range so pretend that it is known in this case. First
6686 -- deal with low bound.
6688 elsif Ekind
(Etype
(LB
)) = E_Signed_Integer_Subtype
6689 and then Scalar_Range
(Etype
(LB
)) = Scalar_Range
(T_Typ
)
6698 -- Likewise for the high bound
6700 if Compile_Time_Known_Value
(HB
) then
6703 elsif Ekind
(Etype
(HB
)) = E_Signed_Integer_Subtype
6704 and then Scalar_Range
(Etype
(HB
)) = Scalar_Range
(T_Typ
)
6714 -- Check for case where everything is static and we can do the
6715 -- check at compile time. This is skipped if we have an access
6716 -- type, since the access value may be null.
6718 -- ??? This code can be improved since you only need to know that
6719 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
6720 -- compile time to emit pertinent messages.
6722 if Known_T_LB
and Known_T_HB
and Known_LB
and Known_HB
6725 -- Floating-point case
6727 if Is_Floating_Point_Type
(S_Typ
) then
6728 Null_Range
:= Expr_Value_R
(HB
) < Expr_Value_R
(LB
);
6730 (Expr_Value_R
(LB
) < Expr_Value_R
(T_LB
))
6732 (Expr_Value_R
(LB
) > Expr_Value_R
(T_HB
));
6735 (Expr_Value_R
(HB
) > Expr_Value_R
(T_HB
))
6737 (Expr_Value_R
(HB
) < Expr_Value_R
(T_LB
));
6739 -- Fixed or discrete type case
6742 Null_Range
:= Expr_Value
(HB
) < Expr_Value
(LB
);
6744 (Expr_Value
(LB
) < Expr_Value
(T_LB
))
6746 (Expr_Value
(LB
) > Expr_Value
(T_HB
));
6749 (Expr_Value
(HB
) > Expr_Value
(T_HB
))
6751 (Expr_Value
(HB
) < Expr_Value
(T_LB
));
6754 if not Null_Range
then
6755 if Out_Of_Range_L
then
6756 if No
(Warn_Node
) then
6758 (Compile_Time_Constraint_Error
6759 (Low_Bound
(Ck_Node
),
6760 "static value out of range of}?", T_Typ
));
6764 (Compile_Time_Constraint_Error
6766 "static range out of bounds of}?", T_Typ
));
6770 if Out_Of_Range_H
then
6771 if No
(Warn_Node
) then
6773 (Compile_Time_Constraint_Error
6774 (High_Bound
(Ck_Node
),
6775 "static value out of range of}?", T_Typ
));
6779 (Compile_Time_Constraint_Error
6781 "static range out of bounds of}?", T_Typ
));
6788 LB
: Node_Id
:= Low_Bound
(Ck_Node
);
6789 HB
: Node_Id
:= High_Bound
(Ck_Node
);
6792 -- If either bound is a discriminant and we are within the
6793 -- record declaration, it is a use of the discriminant in a
6794 -- constraint of a component, and nothing can be checked
6795 -- here. The check will be emitted within the init proc.
6796 -- Before then, the discriminal has no real meaning.
6797 -- Similarly, if the entity is a discriminal, there is no
6798 -- check to perform yet.
6800 -- The same holds within a discriminated synchronized type,
6801 -- where the discriminant may constrain a component or an
6804 if Nkind
(LB
) = N_Identifier
6805 and then Denotes_Discriminant
(LB
, True)
6807 if Current_Scope
= Scope
(Entity
(LB
))
6808 or else Is_Concurrent_Type
(Current_Scope
)
6809 or else Ekind
(Entity
(LB
)) /= E_Discriminant
6814 New_Occurrence_Of
(Discriminal
(Entity
(LB
)), Loc
);
6818 if Nkind
(HB
) = N_Identifier
6819 and then Denotes_Discriminant
(HB
, True)
6821 if Current_Scope
= Scope
(Entity
(HB
))
6822 or else Is_Concurrent_Type
(Current_Scope
)
6823 or else Ekind
(Entity
(HB
)) /= E_Discriminant
6828 New_Occurrence_Of
(Discriminal
(Entity
(HB
)), Loc
);
6832 Cond
:= Discrete_Range_Cond
(Ck_Node
, T_Typ
);
6833 Set_Paren_Count
(Cond
, 1);
6839 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(HB
),
6840 Right_Opnd
=> Duplicate_Subexpr_No_Checks
(LB
)),
6841 Right_Opnd
=> Cond
);
6846 elsif Is_Scalar_Type
(S_Typ
) then
6848 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6849 -- except the above simply sets a flag in the node and lets
6850 -- gigi generate the check base on the Etype of the expression.
6851 -- Sometimes, however we want to do a dynamic check against an
6852 -- arbitrary target type, so we do that here.
6854 if Ekind
(Base_Type
(S_Typ
)) /= Ekind
(Base_Type
(T_Typ
)) then
6855 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
6857 -- For literals, we can tell if the constraint error will be
6858 -- raised at compile time, so we never need a dynamic check, but
6859 -- if the exception will be raised, then post the usual warning,
6860 -- and replace the literal with a raise constraint error
6861 -- expression. As usual, skip this for access types
6863 elsif Compile_Time_Known_Value
(Ck_Node
)
6864 and then not Do_Access
6867 LB
: constant Node_Id
:= Type_Low_Bound
(T_Typ
);
6868 UB
: constant Node_Id
:= Type_High_Bound
(T_Typ
);
6870 Out_Of_Range
: Boolean;
6871 Static_Bounds
: constant Boolean :=
6872 Compile_Time_Known_Value
(LB
)
6873 and Compile_Time_Known_Value
(UB
);
6876 -- Following range tests should use Sem_Eval routine ???
6878 if Static_Bounds
then
6879 if Is_Floating_Point_Type
(S_Typ
) then
6881 (Expr_Value_R
(Ck_Node
) < Expr_Value_R
(LB
))
6883 (Expr_Value_R
(Ck_Node
) > Expr_Value_R
(UB
));
6885 -- Fixed or discrete type
6889 Expr_Value
(Ck_Node
) < Expr_Value
(LB
)
6891 Expr_Value
(Ck_Node
) > Expr_Value
(UB
);
6894 -- Bounds of the type are static and the literal is out of
6895 -- range so output a warning message.
6897 if Out_Of_Range
then
6898 if No
(Warn_Node
) then
6900 (Compile_Time_Constraint_Error
6902 "static value out of range of}?", T_Typ
));
6906 (Compile_Time_Constraint_Error
6908 "static value out of range of}?", T_Typ
));
6913 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
6917 -- Here for the case of a non-static expression, we need a runtime
6918 -- check unless the source type range is guaranteed to be in the
6919 -- range of the target type.
6922 if not In_Subrange_Of
(S_Typ
, T_Typ
) then
6923 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
6928 if Is_Array_Type
(T_Typ
) and then Is_Array_Type
(S_Typ
) then
6929 if Is_Constrained
(T_Typ
) then
6931 Expr_Actual
:= Get_Referenced_Object
(Ck_Node
);
6932 Exptyp
:= Get_Actual_Subtype
(Expr_Actual
);
6934 if Is_Access_Type
(Exptyp
) then
6935 Exptyp
:= Designated_Type
(Exptyp
);
6938 -- String_Literal case. This needs to be handled specially be-
6939 -- cause no index types are available for string literals. The
6940 -- condition is simply:
6942 -- T_Typ'Length = string-literal-length
6944 if Nkind
(Expr_Actual
) = N_String_Literal
then
6947 -- General array case. Here we have a usable actual subtype for
6948 -- the expression, and the condition is built from the two types
6950 -- T_Typ'First < Exptyp'First or else
6951 -- T_Typ'Last > Exptyp'Last or else
6952 -- T_Typ'First(1) < Exptyp'First(1) or else
6953 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6956 elsif Is_Constrained
(Exptyp
) then
6958 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
6964 L_Index
:= First_Index
(T_Typ
);
6965 R_Index
:= First_Index
(Exptyp
);
6967 for Indx
in 1 .. Ndims
loop
6968 if not (Nkind
(L_Index
) = N_Raise_Constraint_Error
6970 Nkind
(R_Index
) = N_Raise_Constraint_Error
)
6972 -- Deal with compile time length check. Note that we
6973 -- skip this in the access case, because the access
6974 -- value may be null, so we cannot know statically.
6977 Subtypes_Statically_Match
6978 (Etype
(L_Index
), Etype
(R_Index
))
6980 -- If the target type is constrained then we
6981 -- have to check for exact equality of bounds
6982 -- (required for qualified expressions).
6984 if Is_Constrained
(T_Typ
) then
6987 Range_Equal_E_Cond
(Exptyp
, T_Typ
, Indx
));
6990 (Cond
, Range_E_Cond
(Exptyp
, T_Typ
, Indx
));
7000 -- Handle cases where we do not get a usable actual subtype that
7001 -- is constrained. This happens for example in the function call
7002 -- and explicit dereference cases. In these cases, we have to get
7003 -- the length or range from the expression itself, making sure we
7004 -- do not evaluate it more than once.
7006 -- Here Ck_Node is the original expression, or more properly the
7007 -- result of applying Duplicate_Expr to the original tree,
7008 -- forcing the result to be a name.
7012 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
7015 -- Build the condition for the explicit dereference case
7017 for Indx
in 1 .. Ndims
loop
7019 (Cond
, Range_N_Cond
(Ck_Node
, T_Typ
, Indx
));
7025 -- For a conversion to an unconstrained array type, generate an
7026 -- Action to check that the bounds of the source value are within
7027 -- the constraints imposed by the target type (RM 4.6(38)). No
7028 -- check is needed for a conversion to an access to unconstrained
7029 -- array type, as 4.6(24.15/2) requires the designated subtypes
7030 -- of the two access types to statically match.
7032 if Nkind
(Parent
(Ck_Node
)) = N_Type_Conversion
7033 and then not Do_Access
7036 Opnd_Index
: Node_Id
;
7037 Targ_Index
: Node_Id
;
7038 Opnd_Range
: Node_Id
;
7041 Opnd_Index
:= First_Index
(Get_Actual_Subtype
(Ck_Node
));
7042 Targ_Index
:= First_Index
(T_Typ
);
7043 while Present
(Opnd_Index
) loop
7045 -- If the index is a range, use its bounds. If it is an
7046 -- entity (as will be the case if it is a named subtype
7047 -- or an itype created for a slice) retrieve its range.
7049 if Is_Entity_Name
(Opnd_Index
)
7050 and then Is_Type
(Entity
(Opnd_Index
))
7052 Opnd_Range
:= Scalar_Range
(Entity
(Opnd_Index
));
7054 Opnd_Range
:= Opnd_Index
;
7057 if Nkind
(Opnd_Range
) = N_Range
then
7059 (Low_Bound
(Opnd_Range
), Etype
(Targ_Index
),
7060 Assume_Valid
=> True)
7063 (High_Bound
(Opnd_Range
), Etype
(Targ_Index
),
7064 Assume_Valid
=> True)
7068 -- If null range, no check needed
7071 Compile_Time_Known_Value
(High_Bound
(Opnd_Range
))
7073 Compile_Time_Known_Value
(Low_Bound
(Opnd_Range
))
7075 Expr_Value
(High_Bound
(Opnd_Range
)) <
7076 Expr_Value
(Low_Bound
(Opnd_Range
))
7080 elsif Is_Out_Of_Range
7081 (Low_Bound
(Opnd_Range
), Etype
(Targ_Index
),
7082 Assume_Valid
=> True)
7085 (High_Bound
(Opnd_Range
), Etype
(Targ_Index
),
7086 Assume_Valid
=> True)
7089 (Compile_Time_Constraint_Error
7090 (Wnode
, "value out of range of}?", T_Typ
));
7096 (Opnd_Range
, Etype
(Targ_Index
)));
7100 Next_Index
(Opnd_Index
);
7101 Next_Index
(Targ_Index
);
7108 -- Construct the test and insert into the tree
7110 if Present
(Cond
) then
7112 Cond
:= Guard_Access
(Cond
, Loc
, Ck_Node
);
7116 (Make_Raise_Constraint_Error
(Loc
,
7118 Reason
=> CE_Range_Check_Failed
));
7122 end Selected_Range_Checks
;
7124 -------------------------------
7125 -- Storage_Checks_Suppressed --
7126 -------------------------------
7128 function Storage_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
7130 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
7131 return Is_Check_Suppressed
(E
, Storage_Check
);
7133 return Scope_Suppress
(Storage_Check
);
7135 end Storage_Checks_Suppressed
;
7137 ---------------------------
7138 -- Tag_Checks_Suppressed --
7139 ---------------------------
7141 function Tag_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
7144 if Kill_Tag_Checks
(E
) then
7146 elsif Checks_May_Be_Suppressed
(E
) then
7147 return Is_Check_Suppressed
(E
, Tag_Check
);
7151 return Scope_Suppress
(Tag_Check
);
7152 end Tag_Checks_Suppressed
;
7154 --------------------------
7155 -- Validity_Check_Range --
7156 --------------------------
7158 procedure Validity_Check_Range
(N
: Node_Id
) is
7160 if Validity_Checks_On
and Validity_Check_Operands
then
7161 if Nkind
(N
) = N_Range
then
7162 Ensure_Valid
(Low_Bound
(N
));
7163 Ensure_Valid
(High_Bound
(N
));
7166 end Validity_Check_Range
;
7168 --------------------------------
7169 -- Validity_Checks_Suppressed --
7170 --------------------------------
7172 function Validity_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
7174 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
7175 return Is_Check_Suppressed
(E
, Validity_Check
);
7177 return Scope_Suppress
(Validity_Check
);
7179 end Validity_Checks_Suppressed
;