1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree
; use Atree
;
27 with Casing
; use Casing
;
28 with Debug
; use Debug
;
29 with Einfo
; use Einfo
;
30 with Elists
; use Elists
;
31 with Eval_Fat
; use Eval_Fat
;
32 with Exp_Ch11
; use Exp_Ch11
;
33 with Exp_Ch2
; use Exp_Ch2
;
34 with Exp_Ch4
; use Exp_Ch4
;
35 with Exp_Pakd
; use Exp_Pakd
;
36 with Exp_Util
; use Exp_Util
;
37 with Expander
; use Expander
;
38 with Freeze
; use Freeze
;
40 with Nlists
; use Nlists
;
41 with Nmake
; use Nmake
;
43 with Output
; use Output
;
44 with Restrict
; use Restrict
;
45 with Rident
; use Rident
;
46 with Rtsfind
; use Rtsfind
;
48 with Sem_Aux
; use Sem_Aux
;
49 with Sem_Ch3
; use Sem_Ch3
;
50 with Sem_Ch8
; use Sem_Ch8
;
51 with Sem_Eval
; use Sem_Eval
;
52 with Sem_Res
; use Sem_Res
;
53 with Sem_Util
; use Sem_Util
;
54 with Sem_Warn
; use Sem_Warn
;
55 with Sinfo
; use Sinfo
;
56 with Sinput
; use Sinput
;
57 with Snames
; use Snames
;
58 with Sprint
; use Sprint
;
59 with Stand
; use Stand
;
60 with Stringt
; use Stringt
;
61 with Targparm
; use Targparm
;
62 with Tbuild
; use Tbuild
;
63 with Ttypes
; use Ttypes
;
64 with Validsw
; use Validsw
;
66 package body Checks
is
68 -- General note: many of these routines are concerned with generating
69 -- checking code to make sure that constraint error is raised at runtime.
70 -- Clearly this code is only needed if the expander is active, since
71 -- otherwise we will not be generating code or going into the runtime
74 -- We therefore disconnect most of these checks if the expander is
75 -- inactive. This has the additional benefit that we do not need to
76 -- worry about the tree being messed up by previous errors (since errors
77 -- turn off expansion anyway).
79 -- There are a few exceptions to the above rule. For instance routines
80 -- such as Apply_Scalar_Range_Check that do not insert any code can be
81 -- safely called even when the Expander is inactive (but Errors_Detected
82 -- is 0). The benefit of executing this code when expansion is off, is
83 -- the ability to emit constraint error warning for static expressions
84 -- even when we are not generating code.
86 -- The above is modified in gnatprove mode to ensure that proper check
87 -- flags are always placed, even if expansion is off.
89 -------------------------------------
90 -- Suppression of Redundant Checks --
91 -------------------------------------
93 -- This unit implements a limited circuit for removal of redundant
94 -- checks. The processing is based on a tracing of simple sequential
95 -- flow. For any sequence of statements, we save expressions that are
96 -- marked to be checked, and then if the same expression appears later
97 -- with the same check, then under certain circumstances, the second
98 -- check can be suppressed.
100 -- Basically, we can suppress the check if we know for certain that
101 -- the previous expression has been elaborated (together with its
102 -- check), and we know that the exception frame is the same, and that
103 -- nothing has happened to change the result of the exception.
105 -- Let us examine each of these three conditions in turn to describe
106 -- how we ensure that this condition is met.
108 -- First, we need to know for certain that the previous expression has
109 -- been executed. This is done principally by the mechanism of calling
110 -- Conditional_Statements_Begin at the start of any statement sequence
111 -- and Conditional_Statements_End at the end. The End call causes all
112 -- checks remembered since the Begin call to be discarded. This does
113 -- miss a few cases, notably the case of a nested BEGIN-END block with
114 -- no exception handlers. But the important thing is to be conservative.
115 -- The other protection is that all checks are discarded if a label
116 -- is encountered, since then the assumption of sequential execution
117 -- is violated, and we don't know enough about the flow.
119 -- Second, we need to know that the exception frame is the same. We
120 -- do this by killing all remembered checks when we enter a new frame.
121 -- Again, that's over-conservative, but generally the cases we can help
122 -- with are pretty local anyway (like the body of a loop for example).
124 -- Third, we must be sure to forget any checks which are no longer valid.
125 -- This is done by two mechanisms, first the Kill_Checks_Variable call is
126 -- used to note any changes to local variables. We only attempt to deal
127 -- with checks involving local variables, so we do not need to worry
128 -- about global variables. Second, a call to any non-global procedure
129 -- causes us to abandon all stored checks, since such a all may affect
130 -- the values of any local variables.
132 -- The following define the data structures used to deal with remembering
133 -- checks so that redundant checks can be eliminated as described above.
135 -- Right now, the only expressions that we deal with are of the form of
136 -- simple local objects (either declared locally, or IN parameters) or
137 -- such objects plus/minus a compile time known constant. We can do
138 -- more later on if it seems worthwhile, but this catches many simple
139 -- cases in practice.
141 -- The following record type reflects a single saved check. An entry
142 -- is made in the stack of saved checks if and only if the expression
143 -- has been elaborated with the indicated checks.
145 type Saved_Check
is record
147 -- Set True if entry is killed by Kill_Checks
150 -- The entity involved in the expression that is checked
153 -- A compile time value indicating the result of adding or
154 -- subtracting a compile time value. This value is to be
155 -- added to the value of the Entity. A value of zero is
156 -- used for the case of a simple entity reference.
158 Check_Type
: Character;
159 -- This is set to 'R' for a range check (in which case Target_Type
160 -- is set to the target type for the range check) or to 'O' for an
161 -- overflow check (in which case Target_Type is set to Empty).
163 Target_Type
: Entity_Id
;
164 -- Used only if Do_Range_Check is set. Records the target type for
165 -- the check. We need this, because a check is a duplicate only if
166 -- it has the same target type (or more accurately one with a
167 -- range that is smaller or equal to the stored target type of a
171 -- The following table keeps track of saved checks. Rather than use an
172 -- extensible table. We just use a table of fixed size, and we discard
173 -- any saved checks that do not fit. That's very unlikely to happen and
174 -- this is only an optimization in any case.
176 Saved_Checks
: array (Int
range 1 .. 200) of Saved_Check
;
177 -- Array of saved checks
179 Num_Saved_Checks
: Nat
:= 0;
180 -- Number of saved checks
182 -- The following stack keeps track of statement ranges. It is treated
183 -- as a stack. When Conditional_Statements_Begin is called, an entry
184 -- is pushed onto this stack containing the value of Num_Saved_Checks
185 -- at the time of the call. Then when Conditional_Statements_End is
186 -- called, this value is popped off and used to reset Num_Saved_Checks.
188 -- Note: again, this is a fixed length stack with a size that should
189 -- always be fine. If the value of the stack pointer goes above the
190 -- limit, then we just forget all saved checks.
192 Saved_Checks_Stack
: array (Int
range 1 .. 100) of Nat
;
193 Saved_Checks_TOS
: Nat
:= 0;
195 -----------------------
196 -- Local Subprograms --
197 -----------------------
199 procedure Apply_Arithmetic_Overflow_Strict
(N
: Node_Id
);
200 -- Used to apply arithmetic overflow checks for all cases except operators
201 -- on signed arithmetic types in MINIMIZED/ELIMINATED case (for which we
202 -- call Apply_Arithmetic_Overflow_Minimized_Eliminated below). N can be a
203 -- signed integer arithmetic operator (but not an if or case expression).
204 -- It is also called for types other than signed integers.
206 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated
(Op
: Node_Id
);
207 -- Used to apply arithmetic overflow checks for the case where the overflow
208 -- checking mode is MINIMIZED or ELIMINATED and we have a signed integer
209 -- arithmetic op (which includes the case of if and case expressions). Note
210 -- that Do_Overflow_Check may or may not be set for node Op. In these modes
211 -- we have work to do even if overflow checking is suppressed.
213 procedure Apply_Division_Check
218 -- N is an N_Op_Div, N_Op_Rem, or N_Op_Mod node. This routine applies
219 -- division checks as required if the Do_Division_Check flag is set.
220 -- Rlo and Rhi give the possible range of the right operand, these values
221 -- can be referenced and trusted only if ROK is set True.
223 procedure Apply_Float_Conversion_Check
225 Target_Typ
: Entity_Id
);
226 -- The checks on a conversion from a floating-point type to an integer
227 -- type are delicate. They have to be performed before conversion, they
228 -- have to raise an exception when the operand is a NaN, and rounding must
229 -- be taken into account to determine the safe bounds of the operand.
231 procedure Apply_Selected_Length_Checks
233 Target_Typ
: Entity_Id
;
234 Source_Typ
: Entity_Id
;
235 Do_Static
: Boolean);
236 -- This is the subprogram that does all the work for Apply_Length_Check
237 -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
238 -- described for the above routines. The Do_Static flag indicates that
239 -- only a static check is to be done.
241 procedure Apply_Selected_Range_Checks
243 Target_Typ
: Entity_Id
;
244 Source_Typ
: Entity_Id
;
245 Do_Static
: Boolean);
246 -- This is the subprogram that does all the work for Apply_Range_Check.
247 -- Expr, Target_Typ and Source_Typ are as described for the above
248 -- routine. The Do_Static flag indicates that only a static check is
251 type Check_Type
is new Check_Id
range Access_Check
.. Division_Check
;
252 function Check_Needed
(Nod
: Node_Id
; Check
: Check_Type
) return Boolean;
253 -- This function is used to see if an access or division by zero check is
254 -- needed. The check is to be applied to a single variable appearing in the
255 -- source, and N is the node for the reference. If N is not of this form,
256 -- True is returned with no further processing. If N is of the right form,
257 -- then further processing determines if the given Check is needed.
259 -- The particular circuit is to see if we have the case of a check that is
260 -- not needed because it appears in the right operand of a short circuited
261 -- conditional where the left operand guards the check. For example:
263 -- if Var = 0 or else Q / Var > 12 then
267 -- In this example, the division check is not required. At the same time
268 -- we can issue warnings for suspicious use of non-short-circuited forms,
271 -- if Var = 0 or Q / Var > 12 then
277 Check_Type
: Character;
278 Target_Type
: Entity_Id
;
279 Entry_OK
: out Boolean;
283 -- This routine is used by Enable_Range_Check and Enable_Overflow_Check
284 -- to see if a check is of the form for optimization, and if so, to see
285 -- if it has already been performed. Expr is the expression to check,
286 -- and Check_Type is 'R' for a range check, 'O' for an overflow check.
287 -- Target_Type is the target type for a range check, and Empty for an
288 -- overflow check. If the entry is not of the form for optimization,
289 -- then Entry_OK is set to False, and the remaining out parameters
290 -- are undefined. If the entry is OK, then Ent/Ofs are set to the
291 -- entity and offset from the expression. Check_Num is the number of
292 -- a matching saved entry in Saved_Checks, or zero if no such entry
295 function Get_Discriminal
(E
: Entity_Id
; Bound
: Node_Id
) return Node_Id
;
296 -- If a discriminal is used in constraining a prival, Return reference
297 -- to the discriminal of the protected body (which renames the parameter
298 -- of the enclosing protected operation). This clumsy transformation is
299 -- needed because privals are created too late and their actual subtypes
300 -- are not available when analysing the bodies of the protected operations.
301 -- This function is called whenever the bound is an entity and the scope
302 -- indicates a protected operation. If the bound is an in-parameter of
303 -- a protected operation that is not a prival, the function returns the
305 -- To be cleaned up???
307 function Guard_Access
310 Ck_Node
: Node_Id
) return Node_Id
;
311 -- In the access type case, guard the test with a test to ensure
312 -- that the access value is non-null, since the checks do not
313 -- not apply to null access values.
315 procedure Install_Static_Check
(R_Cno
: Node_Id
; Loc
: Source_Ptr
);
316 -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
317 -- Constraint_Error node.
319 function Is_Signed_Integer_Arithmetic_Op
(N
: Node_Id
) return Boolean;
320 -- Returns True if node N is for an arithmetic operation with signed
321 -- integer operands. This includes unary and binary operators, and also
322 -- if and case expression nodes where the dependent expressions are of
323 -- a signed integer type. These are the kinds of nodes for which special
324 -- handling applies in MINIMIZED or ELIMINATED overflow checking mode.
326 function Range_Or_Validity_Checks_Suppressed
327 (Expr
: Node_Id
) return Boolean;
328 -- Returns True if either range or validity checks or both are suppressed
329 -- for the type of the given expression, or, if the expression is the name
330 -- of an entity, if these checks are suppressed for the entity.
332 function Selected_Length_Checks
334 Target_Typ
: Entity_Id
;
335 Source_Typ
: Entity_Id
;
336 Warn_Node
: Node_Id
) return Check_Result
;
337 -- Like Apply_Selected_Length_Checks, except it doesn't modify
338 -- anything, just returns a list of nodes as described in the spec of
339 -- this package for the Range_Check function.
341 function Selected_Range_Checks
343 Target_Typ
: Entity_Id
;
344 Source_Typ
: Entity_Id
;
345 Warn_Node
: Node_Id
) return Check_Result
;
346 -- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
347 -- just returns a list of nodes as described in the spec of this package
348 -- for the Range_Check function.
350 ------------------------------
351 -- Access_Checks_Suppressed --
352 ------------------------------
354 function Access_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
356 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
357 return Is_Check_Suppressed
(E
, Access_Check
);
359 return Scope_Suppress
.Suppress
(Access_Check
);
361 end Access_Checks_Suppressed
;
363 -------------------------------------
364 -- Accessibility_Checks_Suppressed --
365 -------------------------------------
367 function Accessibility_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
369 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
370 return Is_Check_Suppressed
(E
, Accessibility_Check
);
372 return Scope_Suppress
.Suppress
(Accessibility_Check
);
374 end Accessibility_Checks_Suppressed
;
376 -----------------------------
377 -- Activate_Division_Check --
378 -----------------------------
380 procedure Activate_Division_Check
(N
: Node_Id
) is
382 Set_Do_Division_Check
(N
, True);
383 Possible_Local_Raise
(N
, Standard_Constraint_Error
);
384 end Activate_Division_Check
;
386 -----------------------------
387 -- Activate_Overflow_Check --
388 -----------------------------
390 procedure Activate_Overflow_Check
(N
: Node_Id
) is
391 Typ
: constant Entity_Id
:= Etype
(N
);
394 -- Floating-point case. If Etype is not set (this can happen when we
395 -- activate a check on a node that has not yet been analyzed), then
396 -- we assume we do not have a floating-point type (as per our spec).
398 if Present
(Typ
) and then Is_Floating_Point_Type
(Typ
) then
400 -- Ignore call if we have no automatic overflow checks on the target
401 -- and Check_Float_Overflow mode is not set. These are the cases in
402 -- which we expect to generate infinities and NaN's with no check.
404 if not (Machine_Overflows_On_Target
or Check_Float_Overflow
) then
407 -- Ignore for unary operations ("+", "-", abs) since these can never
408 -- result in overflow for floating-point cases.
410 elsif Nkind
(N
) in N_Unary_Op
then
413 -- Otherwise we will set the flag
422 -- Nothing to do for Rem/Mod/Plus (overflow not possible, the check
423 -- for zero-divide is a divide check, not an overflow check).
425 if Nkind_In
(N
, N_Op_Rem
, N_Op_Mod
, N_Op_Plus
) then
430 -- Fall through for cases where we do set the flag
432 Set_Do_Overflow_Check
(N
, True);
433 Possible_Local_Raise
(N
, Standard_Constraint_Error
);
434 end Activate_Overflow_Check
;
436 --------------------------
437 -- Activate_Range_Check --
438 --------------------------
440 procedure Activate_Range_Check
(N
: Node_Id
) is
442 Set_Do_Range_Check
(N
, True);
443 Possible_Local_Raise
(N
, Standard_Constraint_Error
);
444 end Activate_Range_Check
;
446 ---------------------------------
447 -- Alignment_Checks_Suppressed --
448 ---------------------------------
450 function Alignment_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
452 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
453 return Is_Check_Suppressed
(E
, Alignment_Check
);
455 return Scope_Suppress
.Suppress
(Alignment_Check
);
457 end Alignment_Checks_Suppressed
;
459 ----------------------------------
460 -- Allocation_Checks_Suppressed --
461 ----------------------------------
463 -- Note: at the current time there are no calls to this function, because
464 -- the relevant check is in the run-time, so it is not a check that the
465 -- compiler can suppress anyway, but we still have to recognize the check
466 -- name Allocation_Check since it is part of the standard.
468 function Allocation_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
470 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
471 return Is_Check_Suppressed
(E
, Allocation_Check
);
473 return Scope_Suppress
.Suppress
(Allocation_Check
);
475 end Allocation_Checks_Suppressed
;
477 -------------------------
478 -- Append_Range_Checks --
479 -------------------------
481 procedure Append_Range_Checks
482 (Checks
: Check_Result
;
484 Suppress_Typ
: Entity_Id
;
485 Static_Sloc
: Source_Ptr
;
488 Internal_Flag_Node
: constant Node_Id
:= Flag_Node
;
489 Internal_Static_Sloc
: constant Source_Ptr
:= Static_Sloc
;
491 Checks_On
: constant Boolean :=
492 (not Index_Checks_Suppressed
(Suppress_Typ
))
493 or else (not Range_Checks_Suppressed
(Suppress_Typ
));
496 -- For now we just return if Checks_On is false, however this should
497 -- be enhanced to check for an always True value in the condition
498 -- and to generate a compilation warning???
500 if not Checks_On
then
505 exit when No
(Checks
(J
));
507 if Nkind
(Checks
(J
)) = N_Raise_Constraint_Error
508 and then Present
(Condition
(Checks
(J
)))
510 if not Has_Dynamic_Range_Check
(Internal_Flag_Node
) then
511 Append_To
(Stmts
, Checks
(J
));
512 Set_Has_Dynamic_Range_Check
(Internal_Flag_Node
);
518 Make_Raise_Constraint_Error
(Internal_Static_Sloc
,
519 Reason
=> CE_Range_Check_Failed
));
522 end Append_Range_Checks
;
524 ------------------------
525 -- Apply_Access_Check --
526 ------------------------
528 procedure Apply_Access_Check
(N
: Node_Id
) is
529 P
: constant Node_Id
:= Prefix
(N
);
532 -- We do not need checks if we are not generating code (i.e. the
533 -- expander is not active). This is not just an optimization, there
534 -- are cases (e.g. with pragma Debug) where generating the checks
535 -- can cause real trouble).
537 if not Expander_Active
then
541 -- No check if short circuiting makes check unnecessary
543 if not Check_Needed
(P
, Access_Check
) then
547 -- No check if accessing the Offset_To_Top component of a dispatch
548 -- table. They are safe by construction.
550 if Tagged_Type_Expansion
551 and then Present
(Etype
(P
))
552 and then RTU_Loaded
(Ada_Tags
)
553 and then RTE_Available
(RE_Offset_To_Top_Ptr
)
554 and then Etype
(P
) = RTE
(RE_Offset_To_Top_Ptr
)
559 -- Otherwise go ahead and install the check
561 Install_Null_Excluding_Check
(P
);
562 end Apply_Access_Check
;
564 -------------------------------
565 -- Apply_Accessibility_Check --
566 -------------------------------
568 procedure Apply_Accessibility_Check
571 Insert_Node
: Node_Id
)
573 Loc
: constant Source_Ptr
:= Sloc
(N
);
574 Param_Ent
: Entity_Id
:= Param_Entity
(N
);
575 Param_Level
: Node_Id
;
576 Type_Level
: Node_Id
;
579 if Ada_Version
>= Ada_2012
580 and then not Present
(Param_Ent
)
581 and then Is_Entity_Name
(N
)
582 and then Ekind_In
(Entity
(N
), E_Constant
, E_Variable
)
583 and then Present
(Effective_Extra_Accessibility
(Entity
(N
)))
585 Param_Ent
:= Entity
(N
);
586 while Present
(Renamed_Object
(Param_Ent
)) loop
588 -- Renamed_Object must return an Entity_Name here
589 -- because of preceding "Present (E_E_A (...))" test.
591 Param_Ent
:= Entity
(Renamed_Object
(Param_Ent
));
595 if Inside_A_Generic
then
598 -- Only apply the run-time check if the access parameter has an
599 -- associated extra access level parameter and when the level of the
600 -- type is less deep than the level of the access parameter, and
601 -- accessibility checks are not suppressed.
603 elsif Present
(Param_Ent
)
604 and then Present
(Extra_Accessibility
(Param_Ent
))
605 and then UI_Gt
(Object_Access_Level
(N
),
606 Deepest_Type_Access_Level
(Typ
))
607 and then not Accessibility_Checks_Suppressed
(Param_Ent
)
608 and then not Accessibility_Checks_Suppressed
(Typ
)
611 New_Occurrence_Of
(Extra_Accessibility
(Param_Ent
), Loc
);
614 Make_Integer_Literal
(Loc
, Deepest_Type_Access_Level
(Typ
));
616 -- Raise Program_Error if the accessibility level of the access
617 -- parameter is deeper than the level of the target access type.
619 Insert_Action
(Insert_Node
,
620 Make_Raise_Program_Error
(Loc
,
623 Left_Opnd
=> Param_Level
,
624 Right_Opnd
=> Type_Level
),
625 Reason
=> PE_Accessibility_Check_Failed
));
627 Analyze_And_Resolve
(N
);
629 end Apply_Accessibility_Check
;
631 --------------------------------
632 -- Apply_Address_Clause_Check --
633 --------------------------------
635 procedure Apply_Address_Clause_Check
(E
: Entity_Id
; N
: Node_Id
) is
636 pragma Assert
(Nkind
(N
) = N_Freeze_Entity
);
638 AC
: constant Node_Id
:= Address_Clause
(E
);
639 Loc
: constant Source_Ptr
:= Sloc
(AC
);
640 Typ
: constant Entity_Id
:= Etype
(E
);
641 Aexp
: constant Node_Id
:= Expression
(AC
);
644 -- Address expression (not necessarily the same as Aexp, for example
645 -- when Aexp is a reference to a constant, in which case Expr gets
646 -- reset to reference the value expression of the constant).
648 procedure Compile_Time_Bad_Alignment
;
649 -- Post error warnings when alignment is known to be incompatible. Note
650 -- that we do not go as far as inserting a raise of Program_Error since
651 -- this is an erroneous case, and it may happen that we are lucky and an
652 -- underaligned address turns out to be OK after all.
654 --------------------------------
655 -- Compile_Time_Bad_Alignment --
656 --------------------------------
658 procedure Compile_Time_Bad_Alignment
is
660 if Address_Clause_Overlay_Warnings
then
662 ("?o?specified address for& may be inconsistent with alignment",
665 ("\?o?program execution may be erroneous (RM 13.3(27))",
667 Set_Address_Warning_Posted
(AC
);
669 end Compile_Time_Bad_Alignment
;
671 -- Start of processing for Apply_Address_Clause_Check
674 -- See if alignment check needed. Note that we never need a check if the
675 -- maximum alignment is one, since the check will always succeed.
677 -- Note: we do not check for checks suppressed here, since that check
678 -- was done in Sem_Ch13 when the address clause was processed. We are
679 -- only called if checks were not suppressed. The reason for this is
680 -- that we have to delay the call to Apply_Alignment_Check till freeze
681 -- time (so that all types etc are elaborated), but we have to check
682 -- the status of check suppressing at the point of the address clause.
685 or else not Check_Address_Alignment
(AC
)
686 or else Maximum_Alignment
= 1
691 -- Obtain expression from address clause
693 Expr
:= Expression
(AC
);
695 -- The following loop digs for the real expression to use in the check
698 -- For constant, get constant expression
700 if Is_Entity_Name
(Expr
)
701 and then Ekind
(Entity
(Expr
)) = E_Constant
703 Expr
:= Constant_Value
(Entity
(Expr
));
705 -- For unchecked conversion, get result to convert
707 elsif Nkind
(Expr
) = N_Unchecked_Type_Conversion
then
708 Expr
:= Expression
(Expr
);
710 -- For (common case) of To_Address call, get argument
712 elsif Nkind
(Expr
) = N_Function_Call
713 and then Is_Entity_Name
(Name
(Expr
))
714 and then Is_RTE
(Entity
(Name
(Expr
)), RE_To_Address
)
716 Expr
:= First
(Parameter_Associations
(Expr
));
718 if Nkind
(Expr
) = N_Parameter_Association
then
719 Expr
:= Explicit_Actual_Parameter
(Expr
);
722 -- We finally have the real expression
729 -- See if we know that Expr has a bad alignment at compile time
731 if Compile_Time_Known_Value
(Expr
)
732 and then (Known_Alignment
(E
) or else Known_Alignment
(Typ
))
735 AL
: Uint
:= Alignment
(Typ
);
738 -- The object alignment might be more restrictive than the
741 if Known_Alignment
(E
) then
745 if Expr_Value
(Expr
) mod AL
/= 0 then
746 Compile_Time_Bad_Alignment
;
752 -- If the expression has the form X'Address, then we can find out if
753 -- the object X has an alignment that is compatible with the object E.
754 -- If it hasn't or we don't know, we defer issuing the warning until
755 -- the end of the compilation to take into account back end annotations.
757 elsif Nkind
(Expr
) = N_Attribute_Reference
758 and then Attribute_Name
(Expr
) = Name_Address
759 and then Has_Compatible_Alignment
(E
, Prefix
(Expr
)) = Known_Compatible
764 -- Here we do not know if the value is acceptable. Strictly we don't
765 -- have to do anything, since if the alignment is bad, we have an
766 -- erroneous program. However we are allowed to check for erroneous
767 -- conditions and we decide to do this by default if the check is not
770 -- However, don't do the check if elaboration code is unwanted
772 if Restriction_Active
(No_Elaboration_Code
) then
775 -- Generate a check to raise PE if alignment may be inappropriate
778 -- If the original expression is a non-static constant, use the
779 -- name of the constant itself rather than duplicating its
780 -- defining expression, which was extracted above.
782 -- Note: Expr is empty if the address-clause is applied to in-mode
783 -- actuals (allowed by 13.1(22)).
785 if not Present
(Expr
)
787 (Is_Entity_Name
(Expression
(AC
))
788 and then Ekind
(Entity
(Expression
(AC
))) = E_Constant
789 and then Nkind
(Parent
(Entity
(Expression
(AC
))))
790 = N_Object_Declaration
)
792 Expr
:= New_Copy_Tree
(Expression
(AC
));
794 Remove_Side_Effects
(Expr
);
797 if No
(Actions
(N
)) then
798 Set_Actions
(N
, New_List
);
801 Prepend_To
(Actions
(N
),
802 Make_Raise_Program_Error
(Loc
,
809 (RTE
(RE_Integer_Address
), Expr
),
811 Make_Attribute_Reference
(Loc
,
812 Prefix
=> New_Occurrence_Of
(E
, Loc
),
813 Attribute_Name
=> Name_Alignment
)),
814 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
815 Reason
=> PE_Misaligned_Address_Value
));
817 Warning_Msg
:= No_Error_Msg
;
818 Analyze
(First
(Actions
(N
)), Suppress
=> All_Checks
);
820 -- If the address clause generated a warning message (for example,
821 -- from Warn_On_Non_Local_Exception mode with the active restriction
822 -- No_Exception_Propagation).
824 if Warning_Msg
/= No_Error_Msg
then
826 -- If the expression has a known at compile time value, then
827 -- once we know the alignment of the type, we can check if the
828 -- exception will be raised or not, and if not, we don't need
829 -- the warning so we will kill the warning later on.
831 if Compile_Time_Known_Value
(Expr
) then
832 Alignment_Warnings
.Append
833 ((E
=> E
, A
=> Expr_Value
(Expr
), W
=> Warning_Msg
));
836 -- Add explanation of the warning that is generated by the check
839 ("\address value may be incompatible with alignment "
840 & "of object?X?", AC
);
847 -- If we have some missing run time component in configurable run time
848 -- mode then just skip the check (it is not required in any case).
850 when RE_Not_Available
=>
852 end Apply_Address_Clause_Check
;
854 -------------------------------------
855 -- Apply_Arithmetic_Overflow_Check --
856 -------------------------------------
858 procedure Apply_Arithmetic_Overflow_Check
(N
: Node_Id
) is
860 -- Use old routine in almost all cases (the only case we are treating
861 -- specially is the case of a signed integer arithmetic op with the
862 -- overflow checking mode set to MINIMIZED or ELIMINATED).
864 if Overflow_Check_Mode
= Strict
865 or else not Is_Signed_Integer_Arithmetic_Op
(N
)
867 Apply_Arithmetic_Overflow_Strict
(N
);
869 -- Otherwise use the new routine for the case of a signed integer
870 -- arithmetic op, with Do_Overflow_Check set to True, and the checking
871 -- mode is MINIMIZED or ELIMINATED.
874 Apply_Arithmetic_Overflow_Minimized_Eliminated
(N
);
876 end Apply_Arithmetic_Overflow_Check
;
878 --------------------------------------
879 -- Apply_Arithmetic_Overflow_Strict --
880 --------------------------------------
882 -- This routine is called only if the type is an integer type, and a
883 -- software arithmetic overflow check may be needed for op (add, subtract,
884 -- or multiply). This check is performed only if Software_Overflow_Checking
885 -- is enabled and Do_Overflow_Check is set. In this case we expand the
886 -- operation into a more complex sequence of tests that ensures that
887 -- overflow is properly caught.
889 -- This is used in CHECKED modes. It is identical to the code for this
890 -- cases before the big overflow earthquake, thus ensuring that in this
891 -- modes we have compatible behavior (and reliability) to what was there
892 -- before. It is also called for types other than signed integers, and if
893 -- the Do_Overflow_Check flag is off.
895 -- Note: we also call this routine if we decide in the MINIMIZED case
896 -- to give up and just generate an overflow check without any fuss.
898 procedure Apply_Arithmetic_Overflow_Strict
(N
: Node_Id
) is
899 Loc
: constant Source_Ptr
:= Sloc
(N
);
900 Typ
: constant Entity_Id
:= Etype
(N
);
901 Rtyp
: constant Entity_Id
:= Root_Type
(Typ
);
904 -- Nothing to do if Do_Overflow_Check not set or overflow checks
907 if not Do_Overflow_Check
(N
) then
911 -- An interesting special case. If the arithmetic operation appears as
912 -- the operand of a type conversion:
916 -- and all the following conditions apply:
918 -- arithmetic operation is for a signed integer type
919 -- target type type1 is a static integer subtype
920 -- range of x and y are both included in the range of type1
921 -- range of x op y is included in the range of type1
922 -- size of type1 is at least twice the result size of op
924 -- then we don't do an overflow check in any case, instead we transform
925 -- the operation so that we end up with:
927 -- type1 (type1 (x) op type1 (y))
929 -- This avoids intermediate overflow before the conversion. It is
930 -- explicitly permitted by RM 3.5.4(24):
932 -- For the execution of a predefined operation of a signed integer
933 -- type, the implementation need not raise Constraint_Error if the
934 -- result is outside the base range of the type, so long as the
935 -- correct result is produced.
937 -- It's hard to imagine that any programmer counts on the exception
938 -- being raised in this case, and in any case it's wrong coding to
939 -- have this expectation, given the RM permission. Furthermore, other
940 -- Ada compilers do allow such out of range results.
942 -- Note that we do this transformation even if overflow checking is
943 -- off, since this is precisely about giving the "right" result and
944 -- avoiding the need for an overflow check.
946 -- Note: this circuit is partially redundant with respect to the similar
947 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
948 -- with cases that do not come through here. We still need the following
949 -- processing even with the Exp_Ch4 code in place, since we want to be
950 -- sure not to generate the arithmetic overflow check in these cases
951 -- (Exp_Ch4 would have a hard time removing them once generated).
953 if Is_Signed_Integer_Type
(Typ
)
954 and then Nkind
(Parent
(N
)) = N_Type_Conversion
956 Conversion_Optimization
: declare
957 Target_Type
: constant Entity_Id
:=
958 Base_Type
(Entity
(Subtype_Mark
(Parent
(N
))));
972 if Is_Integer_Type
(Target_Type
)
973 and then RM_Size
(Root_Type
(Target_Type
)) >= 2 * RM_Size
(Rtyp
)
975 Tlo
:= Expr_Value
(Type_Low_Bound
(Target_Type
));
976 Thi
:= Expr_Value
(Type_High_Bound
(Target_Type
));
979 (Left_Opnd
(N
), LOK
, Llo
, Lhi
, Assume_Valid
=> True);
981 (Right_Opnd
(N
), ROK
, Rlo
, Rhi
, Assume_Valid
=> True);
984 and then Tlo
<= Llo
and then Lhi
<= Thi
985 and then Tlo
<= Rlo
and then Rhi
<= Thi
987 Determine_Range
(N
, VOK
, Vlo
, Vhi
, Assume_Valid
=> True);
989 if VOK
and then Tlo
<= Vlo
and then Vhi
<= Thi
then
990 Rewrite
(Left_Opnd
(N
),
991 Make_Type_Conversion
(Loc
,
992 Subtype_Mark
=> New_Occurrence_Of
(Target_Type
, Loc
),
993 Expression
=> Relocate_Node
(Left_Opnd
(N
))));
995 Rewrite
(Right_Opnd
(N
),
996 Make_Type_Conversion
(Loc
,
997 Subtype_Mark
=> New_Occurrence_Of
(Target_Type
, Loc
),
998 Expression
=> Relocate_Node
(Right_Opnd
(N
))));
1000 -- Rewrite the conversion operand so that the original
1001 -- node is retained, in order to avoid the warning for
1002 -- redundant conversions in Resolve_Type_Conversion.
1004 Rewrite
(N
, Relocate_Node
(N
));
1006 Set_Etype
(N
, Target_Type
);
1008 Analyze_And_Resolve
(Left_Opnd
(N
), Target_Type
);
1009 Analyze_And_Resolve
(Right_Opnd
(N
), Target_Type
);
1011 -- Given that the target type is twice the size of the
1012 -- source type, overflow is now impossible, so we can
1013 -- safely kill the overflow check and return.
1015 Set_Do_Overflow_Check
(N
, False);
1020 end Conversion_Optimization
;
1023 -- Now see if an overflow check is required
1026 Siz
: constant Int
:= UI_To_Int
(Esize
(Rtyp
));
1027 Dsiz
: constant Int
:= Siz
* 2;
1034 -- Skip check if back end does overflow checks, or the overflow flag
1035 -- is not set anyway, or we are not doing code expansion, or the
1036 -- parent node is a type conversion whose operand is an arithmetic
1037 -- operation on signed integers on which the expander can promote
1038 -- later the operands to type Integer (see Expand_N_Type_Conversion).
1040 -- Special case CLI target, where arithmetic overflow checks can be
1041 -- performed for integer and long_integer
1043 if Backend_Overflow_Checks_On_Target
1044 or else not Do_Overflow_Check
(N
)
1045 or else not Expander_Active
1046 or else (Present
(Parent
(N
))
1047 and then Nkind
(Parent
(N
)) = N_Type_Conversion
1048 and then Integer_Promotion_Possible
(Parent
(N
)))
1050 (VM_Target
= CLI_Target
and then Siz
>= Standard_Integer_Size
)
1055 -- Otherwise, generate the full general code for front end overflow
1056 -- detection, which works by doing arithmetic in a larger type:
1062 -- Typ (Checktyp (x) op Checktyp (y));
1064 -- where Typ is the type of the original expression, and Checktyp is
1065 -- an integer type of sufficient length to hold the largest possible
1068 -- If the size of check type exceeds the size of Long_Long_Integer,
1069 -- we use a different approach, expanding to:
1071 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
1073 -- where xxx is Add, Multiply or Subtract as appropriate
1075 -- Find check type if one exists
1077 if Dsiz
<= Standard_Integer_Size
then
1078 Ctyp
:= Standard_Integer
;
1080 elsif Dsiz
<= Standard_Long_Long_Integer_Size
then
1081 Ctyp
:= Standard_Long_Long_Integer
;
1083 -- No check type exists, use runtime call
1086 if Nkind
(N
) = N_Op_Add
then
1087 Cent
:= RE_Add_With_Ovflo_Check
;
1089 elsif Nkind
(N
) = N_Op_Multiply
then
1090 Cent
:= RE_Multiply_With_Ovflo_Check
;
1093 pragma Assert
(Nkind
(N
) = N_Op_Subtract
);
1094 Cent
:= RE_Subtract_With_Ovflo_Check
;
1099 Make_Function_Call
(Loc
,
1100 Name
=> New_Occurrence_Of
(RTE
(Cent
), Loc
),
1101 Parameter_Associations
=> New_List
(
1102 OK_Convert_To
(RTE
(RE_Integer_64
), Left_Opnd
(N
)),
1103 OK_Convert_To
(RTE
(RE_Integer_64
), Right_Opnd
(N
))))));
1105 Analyze_And_Resolve
(N
, Typ
);
1109 -- If we fall through, we have the case where we do the arithmetic
1110 -- in the next higher type and get the check by conversion. In these
1111 -- cases Ctyp is set to the type to be used as the check type.
1113 Opnod
:= Relocate_Node
(N
);
1115 Opnd
:= OK_Convert_To
(Ctyp
, Left_Opnd
(Opnod
));
1118 Set_Etype
(Opnd
, Ctyp
);
1119 Set_Analyzed
(Opnd
, True);
1120 Set_Left_Opnd
(Opnod
, Opnd
);
1122 Opnd
:= OK_Convert_To
(Ctyp
, Right_Opnd
(Opnod
));
1125 Set_Etype
(Opnd
, Ctyp
);
1126 Set_Analyzed
(Opnd
, True);
1127 Set_Right_Opnd
(Opnod
, Opnd
);
1129 -- The type of the operation changes to the base type of the check
1130 -- type, and we reset the overflow check indication, since clearly no
1131 -- overflow is possible now that we are using a double length type.
1132 -- We also set the Analyzed flag to avoid a recursive attempt to
1135 Set_Etype
(Opnod
, Base_Type
(Ctyp
));
1136 Set_Do_Overflow_Check
(Opnod
, False);
1137 Set_Analyzed
(Opnod
, True);
1139 -- Now build the outer conversion
1141 Opnd
:= OK_Convert_To
(Typ
, Opnod
);
1143 Set_Etype
(Opnd
, Typ
);
1145 -- In the discrete type case, we directly generate the range check
1146 -- for the outer operand. This range check will implement the
1147 -- required overflow check.
1149 if Is_Discrete_Type
(Typ
) then
1151 Generate_Range_Check
1152 (Expression
(N
), Typ
, CE_Overflow_Check_Failed
);
1154 -- For other types, we enable overflow checking on the conversion,
1155 -- after setting the node as analyzed to prevent recursive attempts
1156 -- to expand the conversion node.
1159 Set_Analyzed
(Opnd
, True);
1160 Enable_Overflow_Check
(Opnd
);
1165 when RE_Not_Available
=>
1168 end Apply_Arithmetic_Overflow_Strict
;
1170 ----------------------------------------------------
1171 -- Apply_Arithmetic_Overflow_Minimized_Eliminated --
1172 ----------------------------------------------------
1174 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated
(Op
: Node_Id
) is
1175 pragma Assert
(Is_Signed_Integer_Arithmetic_Op
(Op
));
1177 Loc
: constant Source_Ptr
:= Sloc
(Op
);
1178 P
: constant Node_Id
:= Parent
(Op
);
1180 LLIB
: constant Entity_Id
:= Base_Type
(Standard_Long_Long_Integer
);
1181 -- Operands and results are of this type when we convert
1183 Result_Type
: constant Entity_Id
:= Etype
(Op
);
1184 -- Original result type
1186 Check_Mode
: constant Overflow_Mode_Type
:= Overflow_Check_Mode
;
1187 pragma Assert
(Check_Mode
in Minimized_Or_Eliminated
);
1190 -- Ranges of values for result
1193 -- Nothing to do if our parent is one of the following:
1195 -- Another signed integer arithmetic op
1196 -- A membership operation
1197 -- A comparison operation
1199 -- In all these cases, we will process at the higher level (and then
1200 -- this node will be processed during the downwards recursion that
1201 -- is part of the processing in Minimize_Eliminate_Overflows).
1203 if Is_Signed_Integer_Arithmetic_Op
(P
)
1204 or else Nkind
(P
) in N_Membership_Test
1205 or else Nkind
(P
) in N_Op_Compare
1207 -- This is also true for an alternative in a case expression
1209 or else Nkind
(P
) = N_Case_Expression_Alternative
1211 -- This is also true for a range operand in a membership test
1213 or else (Nkind
(P
) = N_Range
1214 and then Nkind
(Parent
(P
)) in N_Membership_Test
)
1219 -- Otherwise, we have a top level arithmetic operation node, and this
1220 -- is where we commence the special processing for MINIMIZED/ELIMINATED
1221 -- modes. This is the case where we tell the machinery not to move into
1222 -- Bignum mode at this top level (of course the top level operation
1223 -- will still be in Bignum mode if either of its operands are of type
1226 Minimize_Eliminate_Overflows
(Op
, Lo
, Hi
, Top_Level
=> True);
1228 -- That call may but does not necessarily change the result type of Op.
1229 -- It is the job of this routine to undo such changes, so that at the
1230 -- top level, we have the proper type. This "undoing" is a point at
1231 -- which a final overflow check may be applied.
1233 -- If the result type was not fiddled we are all set. We go to base
1234 -- types here because things may have been rewritten to generate the
1235 -- base type of the operand types.
1237 if Base_Type
(Etype
(Op
)) = Base_Type
(Result_Type
) then
1242 elsif Is_RTE
(Etype
(Op
), RE_Bignum
) then
1244 -- We need a sequence that looks like:
1246 -- Rnn : Result_Type;
1249 -- M : Mark_Id := SS_Mark;
1251 -- Rnn := Long_Long_Integer'Base (From_Bignum (Op));
1255 -- This block is inserted (using Insert_Actions), and then the node
1256 -- is replaced with a reference to Rnn.
1258 -- A special case arises if our parent is a conversion node. In this
1259 -- case no point in generating a conversion to Result_Type, we will
1260 -- let the parent handle this. Note that this special case is not
1261 -- just about optimization. Consider
1265 -- X := Long_Long_Integer'Base (A * (B ** C));
1267 -- Now the product may fit in Long_Long_Integer but not in Integer.
1268 -- In MINIMIZED/ELIMINATED mode, we don't want to introduce an
1269 -- overflow exception for this intermediate value.
1272 Blk
: constant Node_Id
:= Make_Bignum_Block
(Loc
);
1273 Rnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'R', Op
);
1279 RHS
:= Convert_From_Bignum
(Op
);
1281 if Nkind
(P
) /= N_Type_Conversion
then
1282 Convert_To_And_Rewrite
(Result_Type
, RHS
);
1283 Rtype
:= Result_Type
;
1285 -- Interesting question, do we need a check on that conversion
1286 -- operation. Answer, not if we know the result is in range.
1287 -- At the moment we are not taking advantage of this. To be
1288 -- looked at later ???
1295 (First
(Statements
(Handled_Statement_Sequence
(Blk
))),
1296 Make_Assignment_Statement
(Loc
,
1297 Name
=> New_Occurrence_Of
(Rnn
, Loc
),
1298 Expression
=> RHS
));
1300 Insert_Actions
(Op
, New_List
(
1301 Make_Object_Declaration
(Loc
,
1302 Defining_Identifier
=> Rnn
,
1303 Object_Definition
=> New_Occurrence_Of
(Rtype
, Loc
)),
1306 Rewrite
(Op
, New_Occurrence_Of
(Rnn
, Loc
));
1307 Analyze_And_Resolve
(Op
);
1310 -- Here we know the result is Long_Long_Integer'Base, of that it has
1311 -- been rewritten because the parent operation is a conversion. See
1312 -- Apply_Arithmetic_Overflow_Strict.Conversion_Optimization.
1316 (Etype
(Op
) = LLIB
or else Nkind
(Parent
(Op
)) = N_Type_Conversion
);
1318 -- All we need to do here is to convert the result to the proper
1319 -- result type. As explained above for the Bignum case, we can
1320 -- omit this if our parent is a type conversion.
1322 if Nkind
(P
) /= N_Type_Conversion
then
1323 Convert_To_And_Rewrite
(Result_Type
, Op
);
1326 Analyze_And_Resolve
(Op
);
1328 end Apply_Arithmetic_Overflow_Minimized_Eliminated
;
1330 ----------------------------
1331 -- Apply_Constraint_Check --
1332 ----------------------------
1334 procedure Apply_Constraint_Check
1337 No_Sliding
: Boolean := False)
1339 Desig_Typ
: Entity_Id
;
1342 -- No checks inside a generic (check the instantiations)
1344 if Inside_A_Generic
then
1348 -- Apply required constraint checks
1350 if Is_Scalar_Type
(Typ
) then
1351 Apply_Scalar_Range_Check
(N
, Typ
);
1353 elsif Is_Array_Type
(Typ
) then
1355 -- A useful optimization: an aggregate with only an others clause
1356 -- always has the right bounds.
1358 if Nkind
(N
) = N_Aggregate
1359 and then No
(Expressions
(N
))
1361 (First
(Choices
(First
(Component_Associations
(N
)))))
1367 if Is_Constrained
(Typ
) then
1368 Apply_Length_Check
(N
, Typ
);
1371 Apply_Range_Check
(N
, Typ
);
1374 Apply_Range_Check
(N
, Typ
);
1377 elsif (Is_Record_Type
(Typ
) or else Is_Private_Type
(Typ
))
1378 and then Has_Discriminants
(Base_Type
(Typ
))
1379 and then Is_Constrained
(Typ
)
1381 Apply_Discriminant_Check
(N
, Typ
);
1383 elsif Is_Access_Type
(Typ
) then
1385 Desig_Typ
:= Designated_Type
(Typ
);
1387 -- No checks necessary if expression statically null
1389 if Known_Null
(N
) then
1390 if Can_Never_Be_Null
(Typ
) then
1391 Install_Null_Excluding_Check
(N
);
1394 -- No sliding possible on access to arrays
1396 elsif Is_Array_Type
(Desig_Typ
) then
1397 if Is_Constrained
(Desig_Typ
) then
1398 Apply_Length_Check
(N
, Typ
);
1401 Apply_Range_Check
(N
, Typ
);
1403 elsif Has_Discriminants
(Base_Type
(Desig_Typ
))
1404 and then Is_Constrained
(Desig_Typ
)
1406 Apply_Discriminant_Check
(N
, Typ
);
1409 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1410 -- this check if the constraint node is illegal, as shown by having
1411 -- an error posted. This additional guard prevents cascaded errors
1412 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1414 if Can_Never_Be_Null
(Typ
)
1415 and then not Can_Never_Be_Null
(Etype
(N
))
1416 and then not Error_Posted
(N
)
1418 Install_Null_Excluding_Check
(N
);
1421 end Apply_Constraint_Check
;
1423 ------------------------------
1424 -- Apply_Discriminant_Check --
1425 ------------------------------
1427 procedure Apply_Discriminant_Check
1430 Lhs
: Node_Id
:= Empty
)
1432 Loc
: constant Source_Ptr
:= Sloc
(N
);
1433 Do_Access
: constant Boolean := Is_Access_Type
(Typ
);
1434 S_Typ
: Entity_Id
:= Etype
(N
);
1438 function Denotes_Explicit_Dereference
(Obj
: Node_Id
) return Boolean;
1439 -- A heap object with an indefinite subtype is constrained by its
1440 -- initial value, and assigning to it requires a constraint_check.
1441 -- The target may be an explicit dereference, or a renaming of one.
1443 function Is_Aliased_Unconstrained_Component
return Boolean;
1444 -- It is possible for an aliased component to have a nominal
1445 -- unconstrained subtype (through instantiation). If this is a
1446 -- discriminated component assigned in the expansion of an aggregate
1447 -- in an initialization, the check must be suppressed. This unusual
1448 -- situation requires a predicate of its own.
1450 ----------------------------------
1451 -- Denotes_Explicit_Dereference --
1452 ----------------------------------
1454 function Denotes_Explicit_Dereference
(Obj
: Node_Id
) return Boolean is
1457 Nkind
(Obj
) = N_Explicit_Dereference
1459 (Is_Entity_Name
(Obj
)
1460 and then Present
(Renamed_Object
(Entity
(Obj
)))
1461 and then Nkind
(Renamed_Object
(Entity
(Obj
))) =
1462 N_Explicit_Dereference
);
1463 end Denotes_Explicit_Dereference
;
1465 ----------------------------------------
1466 -- Is_Aliased_Unconstrained_Component --
1467 ----------------------------------------
1469 function Is_Aliased_Unconstrained_Component
return Boolean is
1474 if Nkind
(Lhs
) /= N_Selected_Component
then
1477 Comp
:= Entity
(Selector_Name
(Lhs
));
1478 Pref
:= Prefix
(Lhs
);
1481 if Ekind
(Comp
) /= E_Component
1482 or else not Is_Aliased
(Comp
)
1487 return not Comes_From_Source
(Pref
)
1488 and then In_Instance
1489 and then not Is_Constrained
(Etype
(Comp
));
1490 end Is_Aliased_Unconstrained_Component
;
1492 -- Start of processing for Apply_Discriminant_Check
1496 T_Typ
:= Designated_Type
(Typ
);
1501 -- Nothing to do if discriminant checks are suppressed or else no code
1502 -- is to be generated
1504 if not Expander_Active
1505 or else Discriminant_Checks_Suppressed
(T_Typ
)
1510 -- No discriminant checks necessary for an access when expression is
1511 -- statically Null. This is not only an optimization, it is fundamental
1512 -- because otherwise discriminant checks may be generated in init procs
1513 -- for types containing an access to a not-yet-frozen record, causing a
1514 -- deadly forward reference.
1516 -- Also, if the expression is of an access type whose designated type is
1517 -- incomplete, then the access value must be null and we suppress the
1520 if Known_Null
(N
) then
1523 elsif Is_Access_Type
(S_Typ
) then
1524 S_Typ
:= Designated_Type
(S_Typ
);
1526 if Ekind
(S_Typ
) = E_Incomplete_Type
then
1531 -- If an assignment target is present, then we need to generate the
1532 -- actual subtype if the target is a parameter or aliased object with
1533 -- an unconstrained nominal subtype.
1535 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1536 -- subtype to the parameter and dereference cases, since other aliased
1537 -- objects are unconstrained (unless the nominal subtype is explicitly
1541 and then (Present
(Param_Entity
(Lhs
))
1542 or else (Ada_Version
< Ada_2005
1543 and then not Is_Constrained
(T_Typ
)
1544 and then Is_Aliased_View
(Lhs
)
1545 and then not Is_Aliased_Unconstrained_Component
)
1546 or else (Ada_Version
>= Ada_2005
1547 and then not Is_Constrained
(T_Typ
)
1548 and then Denotes_Explicit_Dereference
(Lhs
)
1549 and then Nkind
(Original_Node
(Lhs
)) /=
1552 T_Typ
:= Get_Actual_Subtype
(Lhs
);
1555 -- Nothing to do if the type is unconstrained (this is the case where
1556 -- the actual subtype in the RM sense of N is unconstrained and no check
1559 if not Is_Constrained
(T_Typ
) then
1562 -- Ada 2005: nothing to do if the type is one for which there is a
1563 -- partial view that is constrained.
1565 elsif Ada_Version
>= Ada_2005
1566 and then Object_Type_Has_Constrained_Partial_View
1567 (Typ
=> Base_Type
(T_Typ
),
1568 Scop
=> Current_Scope
)
1573 -- Nothing to do if the type is an Unchecked_Union
1575 if Is_Unchecked_Union
(Base_Type
(T_Typ
)) then
1579 -- Suppress checks if the subtypes are the same. The check must be
1580 -- preserved in an assignment to a formal, because the constraint is
1581 -- given by the actual.
1583 if Nkind
(Original_Node
(N
)) /= N_Allocator
1585 or else not Is_Entity_Name
(Lhs
)
1586 or else No
(Param_Entity
(Lhs
)))
1589 or else (Do_Access
and then Designated_Type
(Typ
) = S_Typ
))
1590 and then not Is_Aliased_View
(Lhs
)
1595 -- We can also eliminate checks on allocators with a subtype mark that
1596 -- coincides with the context type. The context type may be a subtype
1597 -- without a constraint (common case, a generic actual).
1599 elsif Nkind
(Original_Node
(N
)) = N_Allocator
1600 and then Is_Entity_Name
(Expression
(Original_Node
(N
)))
1603 Alloc_Typ
: constant Entity_Id
:=
1604 Entity
(Expression
(Original_Node
(N
)));
1607 if Alloc_Typ
= T_Typ
1608 or else (Nkind
(Parent
(T_Typ
)) = N_Subtype_Declaration
1609 and then Is_Entity_Name
(
1610 Subtype_Indication
(Parent
(T_Typ
)))
1611 and then Alloc_Typ
= Base_Type
(T_Typ
))
1619 -- See if we have a case where the types are both constrained, and all
1620 -- the constraints are constants. In this case, we can do the check
1621 -- successfully at compile time.
1623 -- We skip this check for the case where the node is rewritten as
1624 -- an allocator, because it already carries the context subtype,
1625 -- and extracting the discriminants from the aggregate is messy.
1627 if Is_Constrained
(S_Typ
)
1628 and then Nkind
(Original_Node
(N
)) /= N_Allocator
1638 -- S_Typ may not have discriminants in the case where it is a
1639 -- private type completed by a default discriminated type. In that
1640 -- case, we need to get the constraints from the underlying type.
1641 -- If the underlying type is unconstrained (i.e. has no default
1642 -- discriminants) no check is needed.
1644 if Has_Discriminants
(S_Typ
) then
1645 Discr
:= First_Discriminant
(S_Typ
);
1646 DconS
:= First_Elmt
(Discriminant_Constraint
(S_Typ
));
1649 Discr
:= First_Discriminant
(Underlying_Type
(S_Typ
));
1652 (Discriminant_Constraint
(Underlying_Type
(S_Typ
)));
1658 -- A further optimization: if T_Typ is derived from S_Typ
1659 -- without imposing a constraint, no check is needed.
1661 if Nkind
(Original_Node
(Parent
(T_Typ
))) =
1662 N_Full_Type_Declaration
1665 Type_Def
: constant Node_Id
:=
1666 Type_Definition
(Original_Node
(Parent
(T_Typ
)));
1668 if Nkind
(Type_Def
) = N_Derived_Type_Definition
1669 and then Is_Entity_Name
(Subtype_Indication
(Type_Def
))
1670 and then Entity
(Subtype_Indication
(Type_Def
)) = S_Typ
1678 -- Constraint may appear in full view of type
1680 if Ekind
(T_Typ
) = E_Private_Subtype
1681 and then Present
(Full_View
(T_Typ
))
1684 First_Elmt
(Discriminant_Constraint
(Full_View
(T_Typ
)));
1687 First_Elmt
(Discriminant_Constraint
(T_Typ
));
1690 while Present
(Discr
) loop
1691 ItemS
:= Node
(DconS
);
1692 ItemT
:= Node
(DconT
);
1694 -- For a discriminated component type constrained by the
1695 -- current instance of an enclosing type, there is no
1696 -- applicable discriminant check.
1698 if Nkind
(ItemT
) = N_Attribute_Reference
1699 and then Is_Access_Type
(Etype
(ItemT
))
1700 and then Is_Entity_Name
(Prefix
(ItemT
))
1701 and then Is_Type
(Entity
(Prefix
(ItemT
)))
1706 -- If the expressions for the discriminants are identical
1707 -- and it is side-effect free (for now just an entity),
1708 -- this may be a shared constraint, e.g. from a subtype
1709 -- without a constraint introduced as a generic actual.
1710 -- Examine other discriminants if any.
1713 and then Is_Entity_Name
(ItemS
)
1717 elsif not Is_OK_Static_Expression
(ItemS
)
1718 or else not Is_OK_Static_Expression
(ItemT
)
1722 elsif Expr_Value
(ItemS
) /= Expr_Value
(ItemT
) then
1723 if Do_Access
then -- needs run-time check.
1726 Apply_Compile_Time_Constraint_Error
1727 (N
, "incorrect value for discriminant&??",
1728 CE_Discriminant_Check_Failed
, Ent
=> Discr
);
1735 Next_Discriminant
(Discr
);
1744 -- Here we need a discriminant check. First build the expression
1745 -- for the comparisons of the discriminants:
1747 -- (n.disc1 /= typ.disc1) or else
1748 -- (n.disc2 /= typ.disc2) or else
1750 -- (n.discn /= typ.discn)
1752 Cond
:= Build_Discriminant_Checks
(N
, T_Typ
);
1754 -- If Lhs is set and is a parameter, then the condition is guarded by:
1755 -- lhs'constrained and then (condition built above)
1757 if Present
(Param_Entity
(Lhs
)) then
1761 Make_Attribute_Reference
(Loc
,
1762 Prefix
=> New_Occurrence_Of
(Param_Entity
(Lhs
), Loc
),
1763 Attribute_Name
=> Name_Constrained
),
1764 Right_Opnd
=> Cond
);
1768 Cond
:= Guard_Access
(Cond
, Loc
, N
);
1772 Make_Raise_Constraint_Error
(Loc
,
1774 Reason
=> CE_Discriminant_Check_Failed
));
1775 end Apply_Discriminant_Check
;
1777 -------------------------
1778 -- Apply_Divide_Checks --
1779 -------------------------
1781 procedure Apply_Divide_Checks
(N
: Node_Id
) is
1782 Loc
: constant Source_Ptr
:= Sloc
(N
);
1783 Typ
: constant Entity_Id
:= Etype
(N
);
1784 Left
: constant Node_Id
:= Left_Opnd
(N
);
1785 Right
: constant Node_Id
:= Right_Opnd
(N
);
1787 Mode
: constant Overflow_Mode_Type
:= Overflow_Check_Mode
;
1788 -- Current overflow checking mode
1798 pragma Warnings
(Off
, Lhi
);
1799 -- Don't actually use this value
1802 -- If we are operating in MINIMIZED or ELIMINATED mode, and we are
1803 -- operating on signed integer types, then the only thing this routine
1804 -- does is to call Apply_Arithmetic_Overflow_Minimized_Eliminated. That
1805 -- procedure will (possibly later on during recursive downward calls),
1806 -- ensure that any needed overflow/division checks are properly applied.
1808 if Mode
in Minimized_Or_Eliminated
1809 and then Is_Signed_Integer_Type
(Typ
)
1811 Apply_Arithmetic_Overflow_Minimized_Eliminated
(N
);
1815 -- Proceed here in SUPPRESSED or CHECKED modes
1818 and then not Backend_Divide_Checks_On_Target
1819 and then Check_Needed
(Right
, Division_Check
)
1821 Determine_Range
(Right
, ROK
, Rlo
, Rhi
, Assume_Valid
=> True);
1823 -- Deal with division check
1825 if Do_Division_Check
(N
)
1826 and then not Division_Checks_Suppressed
(Typ
)
1828 Apply_Division_Check
(N
, Rlo
, Rhi
, ROK
);
1831 -- Deal with overflow check
1833 if Do_Overflow_Check
(N
)
1834 and then not Overflow_Checks_Suppressed
(Etype
(N
))
1836 Set_Do_Overflow_Check
(N
, False);
1838 -- Test for extremely annoying case of xxx'First divided by -1
1839 -- for division of signed integer types (only overflow case).
1841 if Nkind
(N
) = N_Op_Divide
1842 and then Is_Signed_Integer_Type
(Typ
)
1844 Determine_Range
(Left
, LOK
, Llo
, Lhi
, Assume_Valid
=> True);
1845 LLB
:= Expr_Value
(Type_Low_Bound
(Base_Type
(Typ
)));
1847 if ((not ROK
) or else (Rlo
<= (-1) and then (-1) <= Rhi
))
1849 ((not LOK
) or else (Llo
= LLB
))
1852 Make_Raise_Constraint_Error
(Loc
,
1858 Duplicate_Subexpr_Move_Checks
(Left
),
1859 Right_Opnd
=> Make_Integer_Literal
(Loc
, LLB
)),
1863 Left_Opnd
=> Duplicate_Subexpr
(Right
),
1864 Right_Opnd
=> Make_Integer_Literal
(Loc
, -1))),
1866 Reason
=> CE_Overflow_Check_Failed
));
1871 end Apply_Divide_Checks
;
1873 --------------------------
1874 -- Apply_Division_Check --
1875 --------------------------
1877 procedure Apply_Division_Check
1883 pragma Assert
(Do_Division_Check
(N
));
1885 Loc
: constant Source_Ptr
:= Sloc
(N
);
1886 Right
: constant Node_Id
:= Right_Opnd
(N
);
1890 and then not Backend_Divide_Checks_On_Target
1891 and then Check_Needed
(Right
, Division_Check
)
1893 -- See if division by zero possible, and if so generate test. This
1894 -- part of the test is not controlled by the -gnato switch, since
1895 -- it is a Division_Check and not an Overflow_Check.
1897 if Do_Division_Check
(N
) then
1898 Set_Do_Division_Check
(N
, False);
1900 if (not ROK
) or else (Rlo
<= 0 and then 0 <= Rhi
) then
1902 Make_Raise_Constraint_Error
(Loc
,
1905 Left_Opnd
=> Duplicate_Subexpr_Move_Checks
(Right
),
1906 Right_Opnd
=> Make_Integer_Literal
(Loc
, 0)),
1907 Reason
=> CE_Divide_By_Zero
));
1911 end Apply_Division_Check
;
1913 ----------------------------------
1914 -- Apply_Float_Conversion_Check --
1915 ----------------------------------
1917 -- Let F and I be the source and target types of the conversion. The RM
1918 -- specifies that a floating-point value X is rounded to the nearest
1919 -- integer, with halfway cases being rounded away from zero. The rounded
1920 -- value of X is checked against I'Range.
1922 -- The catch in the above paragraph is that there is no good way to know
1923 -- whether the round-to-integer operation resulted in overflow. A remedy is
1924 -- to perform a range check in the floating-point domain instead, however:
1926 -- (1) The bounds may not be known at compile time
1927 -- (2) The check must take into account rounding or truncation.
1928 -- (3) The range of type I may not be exactly representable in F.
1929 -- (4) For the rounding case, The end-points I'First - 0.5 and
1930 -- I'Last + 0.5 may or may not be in range, depending on the
1931 -- sign of I'First and I'Last.
1932 -- (5) X may be a NaN, which will fail any comparison
1934 -- The following steps correctly convert X with rounding:
1936 -- (1) If either I'First or I'Last is not known at compile time, use
1937 -- I'Base instead of I in the next three steps and perform a
1938 -- regular range check against I'Range after conversion.
1939 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1940 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1941 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1942 -- In other words, take one of the closest floating-point numbers
1943 -- (which is an integer value) to I'First, and see if it is in
1945 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1946 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1947 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1948 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1949 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1951 -- For the truncating case, replace steps (2) and (3) as follows:
1952 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1953 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1955 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1956 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1959 procedure Apply_Float_Conversion_Check
1961 Target_Typ
: Entity_Id
)
1963 LB
: constant Node_Id
:= Type_Low_Bound
(Target_Typ
);
1964 HB
: constant Node_Id
:= Type_High_Bound
(Target_Typ
);
1965 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
1966 Expr_Type
: constant Entity_Id
:= Base_Type
(Etype
(Ck_Node
));
1967 Target_Base
: constant Entity_Id
:=
1968 Implementation_Base_Type
(Target_Typ
);
1970 Par
: constant Node_Id
:= Parent
(Ck_Node
);
1971 pragma Assert
(Nkind
(Par
) = N_Type_Conversion
);
1972 -- Parent of check node, must be a type conversion
1974 Truncate
: constant Boolean := Float_Truncate
(Par
);
1975 Max_Bound
: constant Uint
:=
1977 (Machine_Radix_Value
(Expr_Type
),
1978 Machine_Mantissa_Value
(Expr_Type
) - 1) - 1;
1980 -- Largest bound, so bound plus or minus half is a machine number of F
1982 Ifirst
, Ilast
: Uint
;
1983 -- Bounds of integer type
1986 -- Bounds to check in floating-point domain
1988 Lo_OK
, Hi_OK
: Boolean;
1989 -- True iff Lo resp. Hi belongs to I'Range
1991 Lo_Chk
, Hi_Chk
: Node_Id
;
1992 -- Expressions that are False iff check fails
1994 Reason
: RT_Exception_Code
;
1997 -- We do not need checks if we are not generating code (i.e. the full
1998 -- expander is not active). In SPARK mode, we specifically don't want
1999 -- the frontend to expand these checks, which are dealt with directly
2000 -- in the formal verification backend.
2002 if not Expander_Active
then
2006 if not Compile_Time_Known_Value
(LB
)
2007 or not Compile_Time_Known_Value
(HB
)
2010 -- First check that the value falls in the range of the base type,
2011 -- to prevent overflow during conversion and then perform a
2012 -- regular range check against the (dynamic) bounds.
2014 pragma Assert
(Target_Base
/= Target_Typ
);
2016 Temp
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', Par
);
2019 Apply_Float_Conversion_Check
(Ck_Node
, Target_Base
);
2020 Set_Etype
(Temp
, Target_Base
);
2022 Insert_Action
(Parent
(Par
),
2023 Make_Object_Declaration
(Loc
,
2024 Defining_Identifier
=> Temp
,
2025 Object_Definition
=> New_Occurrence_Of
(Target_Typ
, Loc
),
2026 Expression
=> New_Copy_Tree
(Par
)),
2027 Suppress
=> All_Checks
);
2030 Make_Raise_Constraint_Error
(Loc
,
2033 Left_Opnd
=> New_Occurrence_Of
(Temp
, Loc
),
2034 Right_Opnd
=> New_Occurrence_Of
(Target_Typ
, Loc
)),
2035 Reason
=> CE_Range_Check_Failed
));
2036 Rewrite
(Par
, New_Occurrence_Of
(Temp
, Loc
));
2042 -- Get the (static) bounds of the target type
2044 Ifirst
:= Expr_Value
(LB
);
2045 Ilast
:= Expr_Value
(HB
);
2047 -- A simple optimization: if the expression is a universal literal,
2048 -- we can do the comparison with the bounds and the conversion to
2049 -- an integer type statically. The range checks are unchanged.
2051 if Nkind
(Ck_Node
) = N_Real_Literal
2052 and then Etype
(Ck_Node
) = Universal_Real
2053 and then Is_Integer_Type
(Target_Typ
)
2054 and then Nkind
(Parent
(Ck_Node
)) = N_Type_Conversion
2057 Int_Val
: constant Uint
:= UR_To_Uint
(Realval
(Ck_Node
));
2060 if Int_Val
<= Ilast
and then Int_Val
>= Ifirst
then
2062 -- Conversion is safe
2064 Rewrite
(Parent
(Ck_Node
),
2065 Make_Integer_Literal
(Loc
, UI_To_Int
(Int_Val
)));
2066 Analyze_And_Resolve
(Parent
(Ck_Node
), Target_Typ
);
2072 -- Check against lower bound
2074 if Truncate
and then Ifirst
> 0 then
2075 Lo
:= Pred
(Expr_Type
, UR_From_Uint
(Ifirst
));
2079 Lo
:= Succ
(Expr_Type
, UR_From_Uint
(Ifirst
- 1));
2082 elsif abs (Ifirst
) < Max_Bound
then
2083 Lo
:= UR_From_Uint
(Ifirst
) - Ureal_Half
;
2084 Lo_OK
:= (Ifirst
> 0);
2087 Lo
:= Machine
(Expr_Type
, UR_From_Uint
(Ifirst
), Round_Even
, Ck_Node
);
2088 Lo_OK
:= (Lo
>= UR_From_Uint
(Ifirst
));
2093 -- Lo_Chk := (X >= Lo)
2095 Lo_Chk
:= Make_Op_Ge
(Loc
,
2096 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
2097 Right_Opnd
=> Make_Real_Literal
(Loc
, Lo
));
2100 -- Lo_Chk := (X > Lo)
2102 Lo_Chk
:= Make_Op_Gt
(Loc
,
2103 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
2104 Right_Opnd
=> Make_Real_Literal
(Loc
, Lo
));
2107 -- Check against higher bound
2109 if Truncate
and then Ilast
< 0 then
2110 Hi
:= Succ
(Expr_Type
, UR_From_Uint
(Ilast
));
2114 Hi
:= Pred
(Expr_Type
, UR_From_Uint
(Ilast
+ 1));
2117 elsif abs (Ilast
) < Max_Bound
then
2118 Hi
:= UR_From_Uint
(Ilast
) + Ureal_Half
;
2119 Hi_OK
:= (Ilast
< 0);
2121 Hi
:= Machine
(Expr_Type
, UR_From_Uint
(Ilast
), Round_Even
, Ck_Node
);
2122 Hi_OK
:= (Hi
<= UR_From_Uint
(Ilast
));
2127 -- Hi_Chk := (X <= Hi)
2129 Hi_Chk
:= Make_Op_Le
(Loc
,
2130 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
2131 Right_Opnd
=> Make_Real_Literal
(Loc
, Hi
));
2134 -- Hi_Chk := (X < Hi)
2136 Hi_Chk
:= Make_Op_Lt
(Loc
,
2137 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
2138 Right_Opnd
=> Make_Real_Literal
(Loc
, Hi
));
2141 -- If the bounds of the target type are the same as those of the base
2142 -- type, the check is an overflow check as a range check is not
2143 -- performed in these cases.
2145 if Expr_Value
(Type_Low_Bound
(Target_Base
)) = Ifirst
2146 and then Expr_Value
(Type_High_Bound
(Target_Base
)) = Ilast
2148 Reason
:= CE_Overflow_Check_Failed
;
2150 Reason
:= CE_Range_Check_Failed
;
2153 -- Raise CE if either conditions does not hold
2155 Insert_Action
(Ck_Node
,
2156 Make_Raise_Constraint_Error
(Loc
,
2157 Condition
=> Make_Op_Not
(Loc
, Make_And_Then
(Loc
, Lo_Chk
, Hi_Chk
)),
2159 end Apply_Float_Conversion_Check
;
2161 ------------------------
2162 -- Apply_Length_Check --
2163 ------------------------
2165 procedure Apply_Length_Check
2167 Target_Typ
: Entity_Id
;
2168 Source_Typ
: Entity_Id
:= Empty
)
2171 Apply_Selected_Length_Checks
2172 (Ck_Node
, Target_Typ
, Source_Typ
, Do_Static
=> False);
2173 end Apply_Length_Check
;
2175 -------------------------------------
2176 -- Apply_Parameter_Aliasing_Checks --
2177 -------------------------------------
2179 procedure Apply_Parameter_Aliasing_Checks
2183 Loc
: constant Source_Ptr
:= Sloc
(Call
);
2185 function May_Cause_Aliasing
2186 (Formal_1
: Entity_Id
;
2187 Formal_2
: Entity_Id
) return Boolean;
2188 -- Determine whether two formal parameters can alias each other
2189 -- depending on their modes.
2191 function Original_Actual
(N
: Node_Id
) return Node_Id
;
2192 -- The expander may replace an actual with a temporary for the sake of
2193 -- side effect removal. The temporary may hide a potential aliasing as
2194 -- it does not share the address of the actual. This routine attempts
2195 -- to retrieve the original actual.
2197 procedure Overlap_Check
2198 (Actual_1
: Node_Id
;
2200 Formal_1
: Entity_Id
;
2201 Formal_2
: Entity_Id
;
2202 Check
: in out Node_Id
);
2203 -- Create a check to determine whether Actual_1 overlaps with Actual_2.
2204 -- If detailed exception messages are enabled, the check is augmented to
2205 -- provide information about the names of the corresponding formals. See
2206 -- the body for details. Actual_1 and Actual_2 denote the two actuals to
2207 -- be tested. Formal_1 and Formal_2 denote the corresponding formals.
2208 -- Check contains all and-ed simple tests generated so far or remains
2209 -- unchanged in the case of detailed exception messaged.
2211 ------------------------
2212 -- May_Cause_Aliasing --
2213 ------------------------
2215 function May_Cause_Aliasing
2216 (Formal_1
: Entity_Id
;
2217 Formal_2
: Entity_Id
) return Boolean
2220 -- The following combination cannot lead to aliasing
2222 -- Formal 1 Formal 2
2225 if Ekind
(Formal_1
) = E_In_Parameter
2227 Ekind
(Formal_2
) = E_In_Parameter
2231 -- The following combinations may lead to aliasing
2233 -- Formal 1 Formal 2
2243 end May_Cause_Aliasing
;
2245 ---------------------
2246 -- Original_Actual --
2247 ---------------------
2249 function Original_Actual
(N
: Node_Id
) return Node_Id
is
2251 if Nkind
(N
) = N_Type_Conversion
then
2252 return Expression
(N
);
2254 -- The expander created a temporary to capture the result of a type
2255 -- conversion where the expression is the real actual.
2257 elsif Nkind
(N
) = N_Identifier
2258 and then Present
(Original_Node
(N
))
2259 and then Nkind
(Original_Node
(N
)) = N_Type_Conversion
2261 return Expression
(Original_Node
(N
));
2265 end Original_Actual
;
2271 procedure Overlap_Check
2272 (Actual_1
: Node_Id
;
2274 Formal_1
: Entity_Id
;
2275 Formal_2
: Entity_Id
;
2276 Check
: in out Node_Id
)
2279 ID_Casing
: constant Casing_Type
:=
2280 Identifier_Casing
(Source_Index
(Current_Sem_Unit
));
2284 -- Actual_1'Overlaps_Storage (Actual_2)
2287 Make_Attribute_Reference
(Loc
,
2288 Prefix
=> New_Copy_Tree
(Original_Actual
(Actual_1
)),
2289 Attribute_Name
=> Name_Overlaps_Storage
,
2291 New_List
(New_Copy_Tree
(Original_Actual
(Actual_2
))));
2293 -- Generate the following check when detailed exception messages are
2296 -- if Actual_1'Overlaps_Storage (Actual_2) then
2297 -- raise Program_Error with <detailed message>;
2300 if Exception_Extra_Info
then
2303 -- Do not generate location information for internal calls
2305 if Comes_From_Source
(Call
) then
2306 Store_String_Chars
(Build_Location_String
(Loc
));
2307 Store_String_Char
(' ');
2310 Store_String_Chars
("aliased parameters, actuals for """);
2312 Get_Name_String
(Chars
(Formal_1
));
2313 Set_Casing
(ID_Casing
);
2314 Store_String_Chars
(Name_Buffer
(1 .. Name_Len
));
2316 Store_String_Chars
(""" and """);
2318 Get_Name_String
(Chars
(Formal_2
));
2319 Set_Casing
(ID_Casing
);
2320 Store_String_Chars
(Name_Buffer
(1 .. Name_Len
));
2322 Store_String_Chars
(""" overlap");
2324 Insert_Action
(Call
,
2325 Make_If_Statement
(Loc
,
2327 Then_Statements
=> New_List
(
2328 Make_Raise_Statement
(Loc
,
2330 New_Occurrence_Of
(Standard_Program_Error
, Loc
),
2331 Expression
=> Make_String_Literal
(Loc
, End_String
)))));
2333 -- Create a sequence of overlapping checks by and-ing them all
2343 Right_Opnd
=> Cond
);
2353 Formal_1
: Entity_Id
;
2354 Formal_2
: Entity_Id
;
2356 -- Start of processing for Apply_Parameter_Aliasing_Checks
2361 Actual_1
:= First_Actual
(Call
);
2362 Formal_1
:= First_Formal
(Subp
);
2363 while Present
(Actual_1
) and then Present
(Formal_1
) loop
2365 -- Ensure that the actual is an object that is not passed by value.
2366 -- Elementary types are always passed by value, therefore actuals of
2367 -- such types cannot lead to aliasing.
2369 if Is_Object_Reference
(Original_Actual
(Actual_1
))
2370 and then not Is_Elementary_Type
(Etype
(Original_Actual
(Actual_1
)))
2372 Actual_2
:= Next_Actual
(Actual_1
);
2373 Formal_2
:= Next_Formal
(Formal_1
);
2374 while Present
(Actual_2
) and then Present
(Formal_2
) loop
2376 -- The other actual we are testing against must also denote
2377 -- a non pass-by-value object. Generate the check only when
2378 -- the mode of the two formals may lead to aliasing.
2380 if Is_Object_Reference
(Original_Actual
(Actual_2
))
2382 Is_Elementary_Type
(Etype
(Original_Actual
(Actual_2
)))
2383 and then May_Cause_Aliasing
(Formal_1
, Formal_2
)
2386 (Actual_1
=> Actual_1
,
2387 Actual_2
=> Actual_2
,
2388 Formal_1
=> Formal_1
,
2389 Formal_2
=> Formal_2
,
2393 Next_Actual
(Actual_2
);
2394 Next_Formal
(Formal_2
);
2398 Next_Actual
(Actual_1
);
2399 Next_Formal
(Formal_1
);
2402 -- Place a simple check right before the call
2404 if Present
(Check
) and then not Exception_Extra_Info
then
2405 Insert_Action
(Call
,
2406 Make_Raise_Program_Error
(Loc
,
2408 Reason
=> PE_Aliased_Parameters
));
2410 end Apply_Parameter_Aliasing_Checks
;
2412 -------------------------------------
2413 -- Apply_Parameter_Validity_Checks --
2414 -------------------------------------
2416 procedure Apply_Parameter_Validity_Checks
(Subp
: Entity_Id
) is
2417 Subp_Decl
: Node_Id
;
2419 procedure Add_Validity_Check
2420 (Context
: Entity_Id
;
2422 For_Result
: Boolean := False);
2423 -- Add a single 'Valid[_Scalar] check which verifies the initialization
2424 -- of Context. PPC_Nam denotes the pre or post condition pragma name.
2425 -- Set flag For_Result when to verify the result of a function.
2427 procedure Build_PPC_Pragma
(PPC_Nam
: Name_Id
; Check
: Node_Id
);
2428 -- Create a pre or post condition pragma with name PPC_Nam which
2429 -- tests expression Check.
2431 ------------------------
2432 -- Add_Validity_Check --
2433 ------------------------
2435 procedure Add_Validity_Check
2436 (Context
: Entity_Id
;
2438 For_Result
: Boolean := False)
2440 Loc
: constant Source_Ptr
:= Sloc
(Subp
);
2441 Typ
: constant Entity_Id
:= Etype
(Context
);
2446 -- For scalars, generate 'Valid test
2448 if Is_Scalar_Type
(Typ
) then
2451 -- For any non-scalar with scalar parts, generate 'Valid_Scalars test
2453 elsif Scalar_Part_Present
(Typ
) then
2454 Nam
:= Name_Valid_Scalars
;
2456 -- No test needed for other cases (no scalars to test)
2462 -- Step 1: Create the expression to verify the validity of the
2465 Check
:= New_Occurrence_Of
(Context
, Loc
);
2467 -- When processing a function result, use 'Result. Generate
2472 Make_Attribute_Reference
(Loc
,
2474 Attribute_Name
=> Name_Result
);
2478 -- Context['Result]'Valid[_Scalars]
2481 Make_Attribute_Reference
(Loc
,
2483 Attribute_Name
=> Nam
);
2485 -- Step 2: Create a pre or post condition pragma
2487 Build_PPC_Pragma
(PPC_Nam
, Check
);
2488 end Add_Validity_Check
;
2490 ----------------------
2491 -- Build_PPC_Pragma --
2492 ----------------------
2494 procedure Build_PPC_Pragma
(PPC_Nam
: Name_Id
; Check
: Node_Id
) is
2495 Loc
: constant Source_Ptr
:= Sloc
(Subp
);
2502 Pragma_Identifier
=> Make_Identifier
(Loc
, PPC_Nam
),
2503 Pragma_Argument_Associations
=> New_List
(
2504 Make_Pragma_Argument_Association
(Loc
,
2505 Chars
=> Name_Check
,
2506 Expression
=> Check
)));
2508 -- Add a message unless exception messages are suppressed
2510 if not Exception_Locations_Suppressed
then
2511 Append_To
(Pragma_Argument_Associations
(Prag
),
2512 Make_Pragma_Argument_Association
(Loc
,
2513 Chars
=> Name_Message
,
2515 Make_String_Literal
(Loc
,
2516 Strval
=> "failed " & Get_Name_String
(PPC_Nam
) &
2517 " from " & Build_Location_String
(Loc
))));
2520 -- Insert the pragma in the tree
2522 if Nkind
(Parent
(Subp_Decl
)) = N_Compilation_Unit
then
2523 Add_Global_Declaration
(Prag
);
2526 -- PPC pragmas associated with subprogram bodies must be inserted in
2527 -- the declarative part of the body.
2529 elsif Nkind
(Subp_Decl
) = N_Subprogram_Body
then
2530 Decls
:= Declarations
(Subp_Decl
);
2534 Set_Declarations
(Subp_Decl
, Decls
);
2537 Prepend_To
(Decls
, Prag
);
2539 -- Ensure the proper visibility of the subprogram body and its
2546 -- For subprogram declarations insert the PPC pragma right after the
2547 -- declarative node.
2550 Insert_After_And_Analyze
(Subp_Decl
, Prag
);
2552 end Build_PPC_Pragma
;
2557 Subp_Spec
: Node_Id
;
2559 -- Start of processing for Apply_Parameter_Validity_Checks
2562 -- Extract the subprogram specification and declaration nodes
2564 Subp_Spec
:= Parent
(Subp
);
2566 if Nkind
(Subp_Spec
) = N_Defining_Program_Unit_Name
then
2567 Subp_Spec
:= Parent
(Subp_Spec
);
2570 Subp_Decl
:= Parent
(Subp_Spec
);
2572 if not Comes_From_Source
(Subp
)
2574 -- Do not process formal subprograms because the corresponding actual
2575 -- will receive the proper checks when the instance is analyzed.
2577 or else Is_Formal_Subprogram
(Subp
)
2579 -- Do not process imported subprograms since pre and post conditions
2580 -- are never verified on routines coming from a different language.
2582 or else Is_Imported
(Subp
)
2583 or else Is_Intrinsic_Subprogram
(Subp
)
2585 -- The PPC pragmas generated by this routine do not correspond to
2586 -- source aspects, therefore they cannot be applied to abstract
2589 or else Nkind
(Subp_Decl
) = N_Abstract_Subprogram_Declaration
2591 -- Do not consider subprogram renaminds because the renamed entity
2592 -- already has the proper PPC pragmas.
2594 or else Nkind
(Subp_Decl
) = N_Subprogram_Renaming_Declaration
2596 -- Do not process null procedures because there is no benefit of
2597 -- adding the checks to a no action routine.
2599 or else (Nkind
(Subp_Spec
) = N_Procedure_Specification
2600 and then Null_Present
(Subp_Spec
))
2605 -- Inspect all the formals applying aliasing and scalar initialization
2606 -- checks where applicable.
2608 Formal
:= First_Formal
(Subp
);
2609 while Present
(Formal
) loop
2611 -- Generate the following scalar initialization checks for each
2612 -- formal parameter:
2614 -- mode IN - Pre => Formal'Valid[_Scalars]
2615 -- mode IN OUT - Pre, Post => Formal'Valid[_Scalars]
2616 -- mode OUT - Post => Formal'Valid[_Scalars]
2618 if Check_Validity_Of_Parameters
then
2619 if Ekind_In
(Formal
, E_In_Parameter
, E_In_Out_Parameter
) then
2620 Add_Validity_Check
(Formal
, Name_Precondition
, False);
2623 if Ekind_In
(Formal
, E_In_Out_Parameter
, E_Out_Parameter
) then
2624 Add_Validity_Check
(Formal
, Name_Postcondition
, False);
2628 Next_Formal
(Formal
);
2631 -- Generate following scalar initialization check for function result:
2633 -- Post => Subp'Result'Valid[_Scalars]
2635 if Check_Validity_Of_Parameters
and then Ekind
(Subp
) = E_Function
then
2636 Add_Validity_Check
(Subp
, Name_Postcondition
, True);
2638 end Apply_Parameter_Validity_Checks
;
2640 ---------------------------
2641 -- Apply_Predicate_Check --
2642 ---------------------------
2644 procedure Apply_Predicate_Check
(N
: Node_Id
; Typ
: Entity_Id
) is
2648 if Present
(Predicate_Function
(Typ
)) then
2651 while Present
(S
) and then not Is_Subprogram
(S
) loop
2655 -- A predicate check does not apply within internally generated
2656 -- subprograms, such as TSS functions.
2658 if Within_Internal_Subprogram
then
2661 -- If the check appears within the predicate function itself, it
2662 -- means that the user specified a check whose formal is the
2663 -- predicated subtype itself, rather than some covering type. This
2664 -- is likely to be a common error, and thus deserves a warning.
2666 elsif Present
(S
) and then S
= Predicate_Function
(Typ
) then
2668 ("predicate check includes a function call that "
2669 & "requires a predicate check??", Parent
(N
));
2671 ("\this will result in infinite recursion??", Parent
(N
));
2673 Make_Raise_Storage_Error
(Sloc
(N
),
2674 Reason
=> SE_Infinite_Recursion
));
2676 -- Here for normal case of predicate active
2679 -- If the type has a static predicate and the expression is known
2680 -- at compile time, see if the expression satisfies the predicate.
2682 Check_Expression_Against_Static_Predicate
(N
, Typ
);
2685 Make_Predicate_Check
(Typ
, Duplicate_Subexpr
(N
)));
2688 end Apply_Predicate_Check
;
2690 -----------------------
2691 -- Apply_Range_Check --
2692 -----------------------
2694 procedure Apply_Range_Check
2696 Target_Typ
: Entity_Id
;
2697 Source_Typ
: Entity_Id
:= Empty
)
2700 Apply_Selected_Range_Checks
2701 (Ck_Node
, Target_Typ
, Source_Typ
, Do_Static
=> False);
2702 end Apply_Range_Check
;
2704 ------------------------------
2705 -- Apply_Scalar_Range_Check --
2706 ------------------------------
2708 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
2709 -- off if it is already set on.
2711 procedure Apply_Scalar_Range_Check
2713 Target_Typ
: Entity_Id
;
2714 Source_Typ
: Entity_Id
:= Empty
;
2715 Fixed_Int
: Boolean := False)
2717 Parnt
: constant Node_Id
:= Parent
(Expr
);
2719 Arr
: Node_Id
:= Empty
; -- initialize to prevent warning
2720 Arr_Typ
: Entity_Id
:= Empty
; -- initialize to prevent warning
2723 Is_Subscr_Ref
: Boolean;
2724 -- Set true if Expr is a subscript
2726 Is_Unconstrained_Subscr_Ref
: Boolean;
2727 -- Set true if Expr is a subscript of an unconstrained array. In this
2728 -- case we do not attempt to do an analysis of the value against the
2729 -- range of the subscript, since we don't know the actual subtype.
2732 -- Set to True if Expr should be regarded as a real value even though
2733 -- the type of Expr might be discrete.
2735 procedure Bad_Value
;
2736 -- Procedure called if value is determined to be out of range
2742 procedure Bad_Value
is
2744 Apply_Compile_Time_Constraint_Error
2745 (Expr
, "value not in range of}??", CE_Range_Check_Failed
,
2750 -- Start of processing for Apply_Scalar_Range_Check
2753 -- Return if check obviously not needed
2756 -- Not needed inside generic
2760 -- Not needed if previous error
2762 or else Target_Typ
= Any_Type
2763 or else Nkind
(Expr
) = N_Error
2765 -- Not needed for non-scalar type
2767 or else not Is_Scalar_Type
(Target_Typ
)
2769 -- Not needed if we know node raises CE already
2771 or else Raises_Constraint_Error
(Expr
)
2776 -- Now, see if checks are suppressed
2779 Is_List_Member
(Expr
) and then Nkind
(Parnt
) = N_Indexed_Component
;
2781 if Is_Subscr_Ref
then
2782 Arr
:= Prefix
(Parnt
);
2783 Arr_Typ
:= Get_Actual_Subtype_If_Available
(Arr
);
2785 if Is_Access_Type
(Arr_Typ
) then
2786 Arr_Typ
:= Designated_Type
(Arr_Typ
);
2790 if not Do_Range_Check
(Expr
) then
2792 -- Subscript reference. Check for Index_Checks suppressed
2794 if Is_Subscr_Ref
then
2796 -- Check array type and its base type
2798 if Index_Checks_Suppressed
(Arr_Typ
)
2799 or else Index_Checks_Suppressed
(Base_Type
(Arr_Typ
))
2803 -- Check array itself if it is an entity name
2805 elsif Is_Entity_Name
(Arr
)
2806 and then Index_Checks_Suppressed
(Entity
(Arr
))
2810 -- Check expression itself if it is an entity name
2812 elsif Is_Entity_Name
(Expr
)
2813 and then Index_Checks_Suppressed
(Entity
(Expr
))
2818 -- All other cases, check for Range_Checks suppressed
2821 -- Check target type and its base type
2823 if Range_Checks_Suppressed
(Target_Typ
)
2824 or else Range_Checks_Suppressed
(Base_Type
(Target_Typ
))
2828 -- Check expression itself if it is an entity name
2830 elsif Is_Entity_Name
(Expr
)
2831 and then Range_Checks_Suppressed
(Entity
(Expr
))
2835 -- If Expr is part of an assignment statement, then check left
2836 -- side of assignment if it is an entity name.
2838 elsif Nkind
(Parnt
) = N_Assignment_Statement
2839 and then Is_Entity_Name
(Name
(Parnt
))
2840 and then Range_Checks_Suppressed
(Entity
(Name
(Parnt
)))
2847 -- Do not set range checks if they are killed
2849 if Nkind
(Expr
) = N_Unchecked_Type_Conversion
2850 and then Kill_Range_Check
(Expr
)
2855 -- Do not set range checks for any values from System.Scalar_Values
2856 -- since the whole idea of such values is to avoid checking them.
2858 if Is_Entity_Name
(Expr
)
2859 and then Is_RTU
(Scope
(Entity
(Expr
)), System_Scalar_Values
)
2864 -- Now see if we need a check
2866 if No
(Source_Typ
) then
2867 S_Typ
:= Etype
(Expr
);
2869 S_Typ
:= Source_Typ
;
2872 if not Is_Scalar_Type
(S_Typ
) or else S_Typ
= Any_Type
then
2876 Is_Unconstrained_Subscr_Ref
:=
2877 Is_Subscr_Ref
and then not Is_Constrained
(Arr_Typ
);
2879 -- Special checks for floating-point type
2881 if Is_Floating_Point_Type
(S_Typ
) then
2883 -- Always do a range check if the source type includes infinities and
2884 -- the target type does not include infinities. We do not do this if
2885 -- range checks are killed.
2887 if Has_Infinities
(S_Typ
)
2888 and then not Has_Infinities
(Target_Typ
)
2890 Enable_Range_Check
(Expr
);
2894 -- Return if we know expression is definitely in the range of the target
2895 -- type as determined by Determine_Range. Right now we only do this for
2896 -- discrete types, and not fixed-point or floating-point types.
2898 -- The additional less-precise tests below catch these cases
2900 -- Note: skip this if we are given a source_typ, since the point of
2901 -- supplying a Source_Typ is to stop us looking at the expression.
2902 -- We could sharpen this test to be out parameters only ???
2904 if Is_Discrete_Type
(Target_Typ
)
2905 and then Is_Discrete_Type
(Etype
(Expr
))
2906 and then not Is_Unconstrained_Subscr_Ref
2907 and then No
(Source_Typ
)
2910 Tlo
: constant Node_Id
:= Type_Low_Bound
(Target_Typ
);
2911 Thi
: constant Node_Id
:= Type_High_Bound
(Target_Typ
);
2916 if Compile_Time_Known_Value
(Tlo
)
2917 and then Compile_Time_Known_Value
(Thi
)
2920 Lov
: constant Uint
:= Expr_Value
(Tlo
);
2921 Hiv
: constant Uint
:= Expr_Value
(Thi
);
2924 -- If range is null, we for sure have a constraint error
2925 -- (we don't even need to look at the value involved,
2926 -- since all possible values will raise CE).
2933 -- Otherwise determine range of value
2935 Determine_Range
(Expr
, OK
, Lo
, Hi
, Assume_Valid
=> True);
2939 -- If definitely in range, all OK
2941 if Lo
>= Lov
and then Hi
<= Hiv
then
2944 -- If definitely not in range, warn
2946 elsif Lov
> Hi
or else Hiv
< Lo
then
2950 -- Otherwise we don't know
2962 Is_Floating_Point_Type
(S_Typ
)
2963 or else (Is_Fixed_Point_Type
(S_Typ
) and then not Fixed_Int
);
2965 -- Check if we can determine at compile time whether Expr is in the
2966 -- range of the target type. Note that if S_Typ is within the bounds
2967 -- of Target_Typ then this must be the case. This check is meaningful
2968 -- only if this is not a conversion between integer and real types.
2970 if not Is_Unconstrained_Subscr_Ref
2971 and then Is_Discrete_Type
(S_Typ
) = Is_Discrete_Type
(Target_Typ
)
2973 (In_Subrange_Of
(S_Typ
, Target_Typ
, Fixed_Int
)
2975 -- Also check if the expression itself is in the range of the
2976 -- target type if it is a known at compile time value. We skip
2977 -- this test if S_Typ is set since for OUT and IN OUT parameters
2978 -- the Expr itself is not relevant to the checking.
2982 and then Is_In_Range
(Expr
, Target_Typ
,
2983 Assume_Valid
=> True,
2984 Fixed_Int
=> Fixed_Int
,
2985 Int_Real
=> Int_Real
)))
2989 elsif Is_Out_Of_Range
(Expr
, Target_Typ
,
2990 Assume_Valid
=> True,
2991 Fixed_Int
=> Fixed_Int
,
2992 Int_Real
=> Int_Real
)
2997 -- Floating-point case
2998 -- In the floating-point case, we only do range checks if the type is
2999 -- constrained. We definitely do NOT want range checks for unconstrained
3000 -- types, since we want to have infinities
3002 elsif Is_Floating_Point_Type
(S_Typ
) then
3004 -- Normally, we only do range checks if the type is constrained. We do
3005 -- NOT want range checks for unconstrained types, since we want to have
3008 if Is_Constrained
(S_Typ
) then
3009 Enable_Range_Check
(Expr
);
3012 -- For all other cases we enable a range check unconditionally
3015 Enable_Range_Check
(Expr
);
3018 end Apply_Scalar_Range_Check
;
3020 ----------------------------------
3021 -- Apply_Selected_Length_Checks --
3022 ----------------------------------
3024 procedure Apply_Selected_Length_Checks
3026 Target_Typ
: Entity_Id
;
3027 Source_Typ
: Entity_Id
;
3028 Do_Static
: Boolean)
3031 R_Result
: Check_Result
;
3034 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
3035 Checks_On
: constant Boolean :=
3036 (not Index_Checks_Suppressed
(Target_Typ
))
3037 or else (not Length_Checks_Suppressed
(Target_Typ
));
3040 -- Note: this means that we lose some useful warnings if the expander
3041 -- is not active, and we also lose these warnings in SPARK mode ???
3043 if not Expander_Active
then
3048 Selected_Length_Checks
(Ck_Node
, Target_Typ
, Source_Typ
, Empty
);
3050 for J
in 1 .. 2 loop
3051 R_Cno
:= R_Result
(J
);
3052 exit when No
(R_Cno
);
3054 -- A length check may mention an Itype which is attached to a
3055 -- subsequent node. At the top level in a package this can cause
3056 -- an order-of-elaboration problem, so we make sure that the itype
3057 -- is referenced now.
3059 if Ekind
(Current_Scope
) = E_Package
3060 and then Is_Compilation_Unit
(Current_Scope
)
3062 Ensure_Defined
(Target_Typ
, Ck_Node
);
3064 if Present
(Source_Typ
) then
3065 Ensure_Defined
(Source_Typ
, Ck_Node
);
3067 elsif Is_Itype
(Etype
(Ck_Node
)) then
3068 Ensure_Defined
(Etype
(Ck_Node
), Ck_Node
);
3072 -- If the item is a conditional raise of constraint error, then have
3073 -- a look at what check is being performed and ???
3075 if Nkind
(R_Cno
) = N_Raise_Constraint_Error
3076 and then Present
(Condition
(R_Cno
))
3078 Cond
:= Condition
(R_Cno
);
3080 -- Case where node does not now have a dynamic check
3082 if not Has_Dynamic_Length_Check
(Ck_Node
) then
3084 -- If checks are on, just insert the check
3087 Insert_Action
(Ck_Node
, R_Cno
);
3089 if not Do_Static
then
3090 Set_Has_Dynamic_Length_Check
(Ck_Node
);
3093 -- If checks are off, then analyze the length check after
3094 -- temporarily attaching it to the tree in case the relevant
3095 -- condition can be evaluated at compile time. We still want a
3096 -- compile time warning in this case.
3099 Set_Parent
(R_Cno
, Ck_Node
);
3104 -- Output a warning if the condition is known to be True
3106 if Is_Entity_Name
(Cond
)
3107 and then Entity
(Cond
) = Standard_True
3109 Apply_Compile_Time_Constraint_Error
3110 (Ck_Node
, "wrong length for array of}??",
3111 CE_Length_Check_Failed
,
3115 -- If we were only doing a static check, or if checks are not
3116 -- on, then we want to delete the check, since it is not needed.
3117 -- We do this by replacing the if statement by a null statement
3119 elsif Do_Static
or else not Checks_On
then
3120 Remove_Warning_Messages
(R_Cno
);
3121 Rewrite
(R_Cno
, Make_Null_Statement
(Loc
));
3125 Install_Static_Check
(R_Cno
, Loc
);
3128 end Apply_Selected_Length_Checks
;
3130 ---------------------------------
3131 -- Apply_Selected_Range_Checks --
3132 ---------------------------------
3134 procedure Apply_Selected_Range_Checks
3136 Target_Typ
: Entity_Id
;
3137 Source_Typ
: Entity_Id
;
3138 Do_Static
: Boolean)
3140 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
3141 Checks_On
: constant Boolean :=
3142 not Index_Checks_Suppressed
(Target_Typ
)
3144 not Range_Checks_Suppressed
(Target_Typ
);
3148 R_Result
: Check_Result
;
3151 if not Expander_Active
or not Checks_On
then
3156 Selected_Range_Checks
(Ck_Node
, Target_Typ
, Source_Typ
, Empty
);
3158 for J
in 1 .. 2 loop
3159 R_Cno
:= R_Result
(J
);
3160 exit when No
(R_Cno
);
3162 -- The range check requires runtime evaluation. Depending on what its
3163 -- triggering condition is, the check may be converted into a compile
3164 -- time constraint check.
3166 if Nkind
(R_Cno
) = N_Raise_Constraint_Error
3167 and then Present
(Condition
(R_Cno
))
3169 Cond
:= Condition
(R_Cno
);
3171 -- Insert the range check before the related context. Note that
3172 -- this action analyses the triggering condition.
3174 Insert_Action
(Ck_Node
, R_Cno
);
3176 -- This old code doesn't make sense, why is the context flagged as
3177 -- requiring dynamic range checks now in the middle of generating
3180 if not Do_Static
then
3181 Set_Has_Dynamic_Range_Check
(Ck_Node
);
3184 -- The triggering condition evaluates to True, the range check
3185 -- can be converted into a compile time constraint check.
3187 if Is_Entity_Name
(Cond
)
3188 and then Entity
(Cond
) = Standard_True
3190 -- Since an N_Range is technically not an expression, we have
3191 -- to set one of the bounds to C_E and then just flag the
3192 -- N_Range. The warning message will point to the lower bound
3193 -- and complain about a range, which seems OK.
3195 if Nkind
(Ck_Node
) = N_Range
then
3196 Apply_Compile_Time_Constraint_Error
3197 (Low_Bound
(Ck_Node
),
3198 "static range out of bounds of}??",
3199 CE_Range_Check_Failed
,
3203 Set_Raises_Constraint_Error
(Ck_Node
);
3206 Apply_Compile_Time_Constraint_Error
3208 "static value out of range of}??",
3209 CE_Range_Check_Failed
,
3214 -- If we were only doing a static check, or if checks are not
3215 -- on, then we want to delete the check, since it is not needed.
3216 -- We do this by replacing the if statement by a null statement
3218 -- Why are we even generating checks if checks are turned off ???
3220 elsif Do_Static
or else not Checks_On
then
3221 Remove_Warning_Messages
(R_Cno
);
3222 Rewrite
(R_Cno
, Make_Null_Statement
(Loc
));
3225 -- The range check raises Constrant_Error explicitly
3228 Install_Static_Check
(R_Cno
, Loc
);
3231 end Apply_Selected_Range_Checks
;
3233 -------------------------------
3234 -- Apply_Static_Length_Check --
3235 -------------------------------
3237 procedure Apply_Static_Length_Check
3239 Target_Typ
: Entity_Id
;
3240 Source_Typ
: Entity_Id
:= Empty
)
3243 Apply_Selected_Length_Checks
3244 (Expr
, Target_Typ
, Source_Typ
, Do_Static
=> True);
3245 end Apply_Static_Length_Check
;
3247 -------------------------------------
3248 -- Apply_Subscript_Validity_Checks --
3249 -------------------------------------
3251 procedure Apply_Subscript_Validity_Checks
(Expr
: Node_Id
) is
3255 pragma Assert
(Nkind
(Expr
) = N_Indexed_Component
);
3257 -- Loop through subscripts
3259 Sub
:= First
(Expressions
(Expr
));
3260 while Present
(Sub
) loop
3262 -- Check one subscript. Note that we do not worry about enumeration
3263 -- type with holes, since we will convert the value to a Pos value
3264 -- for the subscript, and that convert will do the necessary validity
3267 Ensure_Valid
(Sub
, Holes_OK
=> True);
3269 -- Move to next subscript
3273 end Apply_Subscript_Validity_Checks
;
3275 ----------------------------------
3276 -- Apply_Type_Conversion_Checks --
3277 ----------------------------------
3279 procedure Apply_Type_Conversion_Checks
(N
: Node_Id
) is
3280 Target_Type
: constant Entity_Id
:= Etype
(N
);
3281 Target_Base
: constant Entity_Id
:= Base_Type
(Target_Type
);
3282 Expr
: constant Node_Id
:= Expression
(N
);
3284 Expr_Type
: constant Entity_Id
:= Underlying_Type
(Etype
(Expr
));
3285 -- Note: if Etype (Expr) is a private type without discriminants, its
3286 -- full view might have discriminants with defaults, so we need the
3287 -- full view here to retrieve the constraints.
3290 if Inside_A_Generic
then
3293 -- Skip these checks if serious errors detected, there are some nasty
3294 -- situations of incomplete trees that blow things up.
3296 elsif Serious_Errors_Detected
> 0 then
3299 -- Never generate discriminant checks for Unchecked_Union types
3301 elsif Present
(Expr_Type
)
3302 and then Is_Unchecked_Union
(Expr_Type
)
3306 -- Scalar type conversions of the form Target_Type (Expr) require a
3307 -- range check if we cannot be sure that Expr is in the base type of
3308 -- Target_Typ and also that Expr is in the range of Target_Typ. These
3309 -- are not quite the same condition from an implementation point of
3310 -- view, but clearly the second includes the first.
3312 elsif Is_Scalar_Type
(Target_Type
) then
3314 Conv_OK
: constant Boolean := Conversion_OK
(N
);
3315 -- If the Conversion_OK flag on the type conversion is set and no
3316 -- floating-point type is involved in the type conversion then
3317 -- fixed-point values must be read as integral values.
3319 Float_To_Int
: constant Boolean :=
3320 Is_Floating_Point_Type
(Expr_Type
)
3321 and then Is_Integer_Type
(Target_Type
);
3324 if not Overflow_Checks_Suppressed
(Target_Base
)
3325 and then not Overflow_Checks_Suppressed
(Target_Type
)
3327 In_Subrange_Of
(Expr_Type
, Target_Base
, Fixed_Int
=> Conv_OK
)
3328 and then not Float_To_Int
3330 Activate_Overflow_Check
(N
);
3333 if not Range_Checks_Suppressed
(Target_Type
)
3334 and then not Range_Checks_Suppressed
(Expr_Type
)
3336 if Float_To_Int
then
3337 Apply_Float_Conversion_Check
(Expr
, Target_Type
);
3339 Apply_Scalar_Range_Check
3340 (Expr
, Target_Type
, Fixed_Int
=> Conv_OK
);
3342 -- If the target type has predicates, we need to indicate
3343 -- the need for a check, even if Determine_Range finds that
3344 -- the value is within bounds. This may be the case e.g for
3345 -- a division with a constant denominator.
3347 if Has_Predicates
(Target_Type
) then
3348 Enable_Range_Check
(Expr
);
3354 elsif Comes_From_Source
(N
)
3355 and then not Discriminant_Checks_Suppressed
(Target_Type
)
3356 and then Is_Record_Type
(Target_Type
)
3357 and then Is_Derived_Type
(Target_Type
)
3358 and then not Is_Tagged_Type
(Target_Type
)
3359 and then not Is_Constrained
(Target_Type
)
3360 and then Present
(Stored_Constraint
(Target_Type
))
3362 -- An unconstrained derived type may have inherited discriminant.
3363 -- Build an actual discriminant constraint list using the stored
3364 -- constraint, to verify that the expression of the parent type
3365 -- satisfies the constraints imposed by the (unconstrained) derived
3366 -- type. This applies to value conversions, not to view conversions
3370 Loc
: constant Source_Ptr
:= Sloc
(N
);
3372 Constraint
: Elmt_Id
;
3373 Discr_Value
: Node_Id
;
3376 New_Constraints
: constant Elist_Id
:= New_Elmt_List
;
3377 Old_Constraints
: constant Elist_Id
:=
3378 Discriminant_Constraint
(Expr_Type
);
3381 Constraint
:= First_Elmt
(Stored_Constraint
(Target_Type
));
3382 while Present
(Constraint
) loop
3383 Discr_Value
:= Node
(Constraint
);
3385 if Is_Entity_Name
(Discr_Value
)
3386 and then Ekind
(Entity
(Discr_Value
)) = E_Discriminant
3388 Discr
:= Corresponding_Discriminant
(Entity
(Discr_Value
));
3391 and then Scope
(Discr
) = Base_Type
(Expr_Type
)
3393 -- Parent is constrained by new discriminant. Obtain
3394 -- Value of original discriminant in expression. If the
3395 -- new discriminant has been used to constrain more than
3396 -- one of the stored discriminants, this will provide the
3397 -- required consistency check.
3400 (Make_Selected_Component
(Loc
,
3402 Duplicate_Subexpr_No_Checks
3403 (Expr
, Name_Req
=> True),
3405 Make_Identifier
(Loc
, Chars
(Discr
))),
3409 -- Discriminant of more remote ancestor ???
3414 -- Derived type definition has an explicit value for this
3415 -- stored discriminant.
3419 (Duplicate_Subexpr_No_Checks
(Discr_Value
),
3423 Next_Elmt
(Constraint
);
3426 -- Use the unconstrained expression type to retrieve the
3427 -- discriminants of the parent, and apply momentarily the
3428 -- discriminant constraint synthesized above.
3430 Set_Discriminant_Constraint
(Expr_Type
, New_Constraints
);
3431 Cond
:= Build_Discriminant_Checks
(Expr
, Expr_Type
);
3432 Set_Discriminant_Constraint
(Expr_Type
, Old_Constraints
);
3435 Make_Raise_Constraint_Error
(Loc
,
3437 Reason
=> CE_Discriminant_Check_Failed
));
3440 -- For arrays, checks are set now, but conversions are applied during
3441 -- expansion, to take into accounts changes of representation. The
3442 -- checks become range checks on the base type or length checks on the
3443 -- subtype, depending on whether the target type is unconstrained or
3444 -- constrained. Note that the range check is put on the expression of a
3445 -- type conversion, while the length check is put on the type conversion
3448 elsif Is_Array_Type
(Target_Type
) then
3449 if Is_Constrained
(Target_Type
) then
3450 Set_Do_Length_Check
(N
);
3452 Set_Do_Range_Check
(Expr
);
3455 end Apply_Type_Conversion_Checks
;
3457 ----------------------------------------------
3458 -- Apply_Universal_Integer_Attribute_Checks --
3459 ----------------------------------------------
3461 procedure Apply_Universal_Integer_Attribute_Checks
(N
: Node_Id
) is
3462 Loc
: constant Source_Ptr
:= Sloc
(N
);
3463 Typ
: constant Entity_Id
:= Etype
(N
);
3466 if Inside_A_Generic
then
3469 -- Nothing to do if checks are suppressed
3471 elsif Range_Checks_Suppressed
(Typ
)
3472 and then Overflow_Checks_Suppressed
(Typ
)
3476 -- Nothing to do if the attribute does not come from source. The
3477 -- internal attributes we generate of this type do not need checks,
3478 -- and furthermore the attempt to check them causes some circular
3479 -- elaboration orders when dealing with packed types.
3481 elsif not Comes_From_Source
(N
) then
3484 -- If the prefix is a selected component that depends on a discriminant
3485 -- the check may improperly expose a discriminant instead of using
3486 -- the bounds of the object itself. Set the type of the attribute to
3487 -- the base type of the context, so that a check will be imposed when
3488 -- needed (e.g. if the node appears as an index).
3490 elsif Nkind
(Prefix
(N
)) = N_Selected_Component
3491 and then Ekind
(Typ
) = E_Signed_Integer_Subtype
3492 and then Depends_On_Discriminant
(Scalar_Range
(Typ
))
3494 Set_Etype
(N
, Base_Type
(Typ
));
3496 -- Otherwise, replace the attribute node with a type conversion node
3497 -- whose expression is the attribute, retyped to universal integer, and
3498 -- whose subtype mark is the target type. The call to analyze this
3499 -- conversion will set range and overflow checks as required for proper
3500 -- detection of an out of range value.
3503 Set_Etype
(N
, Universal_Integer
);
3504 Set_Analyzed
(N
, True);
3507 Make_Type_Conversion
(Loc
,
3508 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
3509 Expression
=> Relocate_Node
(N
)));
3511 Analyze_And_Resolve
(N
, Typ
);
3514 end Apply_Universal_Integer_Attribute_Checks
;
3516 -------------------------------------
3517 -- Atomic_Synchronization_Disabled --
3518 -------------------------------------
3520 -- Note: internally Disable/Enable_Atomic_Synchronization is implemented
3521 -- using a bogus check called Atomic_Synchronization. This is to make it
3522 -- more convenient to get exactly the same semantics as [Un]Suppress.
3524 function Atomic_Synchronization_Disabled
(E
: Entity_Id
) return Boolean is
3526 -- If debug flag d.e is set, always return False, i.e. all atomic sync
3527 -- looks enabled, since it is never disabled.
3529 if Debug_Flag_Dot_E
then
3532 -- If debug flag d.d is set then always return True, i.e. all atomic
3533 -- sync looks disabled, since it always tests True.
3535 elsif Debug_Flag_Dot_D
then
3538 -- If entity present, then check result for that entity
3540 elsif Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
3541 return Is_Check_Suppressed
(E
, Atomic_Synchronization
);
3543 -- Otherwise result depends on current scope setting
3546 return Scope_Suppress
.Suppress
(Atomic_Synchronization
);
3548 end Atomic_Synchronization_Disabled
;
3550 -------------------------------
3551 -- Build_Discriminant_Checks --
3552 -------------------------------
3554 function Build_Discriminant_Checks
3556 T_Typ
: Entity_Id
) return Node_Id
3558 Loc
: constant Source_Ptr
:= Sloc
(N
);
3561 Disc_Ent
: Entity_Id
;
3565 function Aggregate_Discriminant_Val
(Disc
: Entity_Id
) return Node_Id
;
3567 ----------------------------------
3568 -- Aggregate_Discriminant_Value --
3569 ----------------------------------
3571 function Aggregate_Discriminant_Val
(Disc
: Entity_Id
) return Node_Id
is
3575 -- The aggregate has been normalized with named associations. We use
3576 -- the Chars field to locate the discriminant to take into account
3577 -- discriminants in derived types, which carry the same name as those
3580 Assoc
:= First
(Component_Associations
(N
));
3581 while Present
(Assoc
) loop
3582 if Chars
(First
(Choices
(Assoc
))) = Chars
(Disc
) then
3583 return Expression
(Assoc
);
3589 -- Discriminant must have been found in the loop above
3591 raise Program_Error
;
3592 end Aggregate_Discriminant_Val
;
3594 -- Start of processing for Build_Discriminant_Checks
3597 -- Loop through discriminants evolving the condition
3600 Disc
:= First_Elmt
(Discriminant_Constraint
(T_Typ
));
3602 -- For a fully private type, use the discriminants of the parent type
3604 if Is_Private_Type
(T_Typ
)
3605 and then No
(Full_View
(T_Typ
))
3607 Disc_Ent
:= First_Discriminant
(Etype
(Base_Type
(T_Typ
)));
3609 Disc_Ent
:= First_Discriminant
(T_Typ
);
3612 while Present
(Disc
) loop
3613 Dval
:= Node
(Disc
);
3615 if Nkind
(Dval
) = N_Identifier
3616 and then Ekind
(Entity
(Dval
)) = E_Discriminant
3618 Dval
:= New_Occurrence_Of
(Discriminal
(Entity
(Dval
)), Loc
);
3620 Dval
:= Duplicate_Subexpr_No_Checks
(Dval
);
3623 -- If we have an Unchecked_Union node, we can infer the discriminants
3626 if Is_Unchecked_Union
(Base_Type
(T_Typ
)) then
3628 Get_Discriminant_Value
(
3629 First_Discriminant
(T_Typ
),
3631 Stored_Constraint
(T_Typ
)));
3633 elsif Nkind
(N
) = N_Aggregate
then
3635 Duplicate_Subexpr_No_Checks
3636 (Aggregate_Discriminant_Val
(Disc_Ent
));
3640 Make_Selected_Component
(Loc
,
3642 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
3643 Selector_Name
=> Make_Identifier
(Loc
, Chars
(Disc_Ent
)));
3645 Set_Is_In_Discriminant_Check
(Dref
);
3648 Evolve_Or_Else
(Cond
,
3651 Right_Opnd
=> Dval
));
3654 Next_Discriminant
(Disc_Ent
);
3658 end Build_Discriminant_Checks
;
3664 function Check_Needed
(Nod
: Node_Id
; Check
: Check_Type
) return Boolean is
3671 function Left_Expression
(Op
: Node_Id
) return Node_Id
;
3672 -- Return the relevant expression from the left operand of the given
3673 -- short circuit form: this is LO itself, except if LO is a qualified
3674 -- expression, a type conversion, or an expression with actions, in
3675 -- which case this is Left_Expression (Expression (LO)).
3677 ---------------------
3678 -- Left_Expression --
3679 ---------------------
3681 function Left_Expression
(Op
: Node_Id
) return Node_Id
is
3682 LE
: Node_Id
:= Left_Opnd
(Op
);
3684 while Nkind_In
(LE
, N_Qualified_Expression
,
3686 N_Expression_With_Actions
)
3688 LE
:= Expression
(LE
);
3692 end Left_Expression
;
3694 -- Start of processing for Check_Needed
3697 -- Always check if not simple entity
3699 if Nkind
(Nod
) not in N_Has_Entity
3700 or else not Comes_From_Source
(Nod
)
3705 -- Look up tree for short circuit
3712 -- Done if out of subexpression (note that we allow generated stuff
3713 -- such as itype declarations in this context, to keep the loop going
3714 -- since we may well have generated such stuff in complex situations.
3715 -- Also done if no parent (probably an error condition, but no point
3716 -- in behaving nasty if we find it).
3719 or else (K
not in N_Subexpr
and then Comes_From_Source
(P
))
3723 -- Or/Or Else case, where test is part of the right operand, or is
3724 -- part of one of the actions associated with the right operand, and
3725 -- the left operand is an equality test.
3727 elsif K
= N_Op_Or
then
3728 exit when N
= Right_Opnd
(P
)
3729 and then Nkind
(Left_Expression
(P
)) = N_Op_Eq
;
3731 elsif K
= N_Or_Else
then
3732 exit when (N
= Right_Opnd
(P
)
3735 and then List_Containing
(N
) = Actions
(P
)))
3736 and then Nkind
(Left_Expression
(P
)) = N_Op_Eq
;
3738 -- Similar test for the And/And then case, where the left operand
3739 -- is an inequality test.
3741 elsif K
= N_Op_And
then
3742 exit when N
= Right_Opnd
(P
)
3743 and then Nkind
(Left_Expression
(P
)) = N_Op_Ne
;
3745 elsif K
= N_And_Then
then
3746 exit when (N
= Right_Opnd
(P
)
3749 and then List_Containing
(N
) = Actions
(P
)))
3750 and then Nkind
(Left_Expression
(P
)) = N_Op_Ne
;
3756 -- If we fall through the loop, then we have a conditional with an
3757 -- appropriate test as its left operand, so look further.
3759 L
:= Left_Expression
(P
);
3761 -- L is an "=" or "/=" operator: extract its operands
3763 R
:= Right_Opnd
(L
);
3766 -- Left operand of test must match original variable
3768 if Nkind
(L
) not in N_Has_Entity
or else Entity
(L
) /= Entity
(Nod
) then
3772 -- Right operand of test must be key value (zero or null)
3775 when Access_Check
=>
3776 if not Known_Null
(R
) then
3780 when Division_Check
=>
3781 if not Compile_Time_Known_Value
(R
)
3782 or else Expr_Value
(R
) /= Uint_0
3788 raise Program_Error
;
3791 -- Here we have the optimizable case, warn if not short-circuited
3793 if K
= N_Op_And
or else K
= N_Op_Or
then
3794 Error_Msg_Warn
:= SPARK_Mode
/= On
;
3797 when Access_Check
=>
3798 if GNATprove_Mode
then
3800 ("Constraint_Error might have been raised (access check)",
3804 ("Constraint_Error may be raised (access check)??",
3808 when Division_Check
=>
3809 if GNATprove_Mode
then
3811 ("Constraint_Error might have been raised (zero divide)",
3815 ("Constraint_Error may be raised (zero divide)??",
3820 raise Program_Error
;
3823 if K
= N_Op_And
then
3824 Error_Msg_N
-- CODEFIX
3825 ("use `AND THEN` instead of AND??", P
);
3827 Error_Msg_N
-- CODEFIX
3828 ("use `OR ELSE` instead of OR??", P
);
3831 -- If not short-circuited, we need the check
3835 -- If short-circuited, we can omit the check
3842 -----------------------------------
3843 -- Check_Valid_Lvalue_Subscripts --
3844 -----------------------------------
3846 procedure Check_Valid_Lvalue_Subscripts
(Expr
: Node_Id
) is
3848 -- Skip this if range checks are suppressed
3850 if Range_Checks_Suppressed
(Etype
(Expr
)) then
3853 -- Only do this check for expressions that come from source. We assume
3854 -- that expander generated assignments explicitly include any necessary
3855 -- checks. Note that this is not just an optimization, it avoids
3856 -- infinite recursions.
3858 elsif not Comes_From_Source
(Expr
) then
3861 -- For a selected component, check the prefix
3863 elsif Nkind
(Expr
) = N_Selected_Component
then
3864 Check_Valid_Lvalue_Subscripts
(Prefix
(Expr
));
3867 -- Case of indexed component
3869 elsif Nkind
(Expr
) = N_Indexed_Component
then
3870 Apply_Subscript_Validity_Checks
(Expr
);
3872 -- Prefix may itself be or contain an indexed component, and these
3873 -- subscripts need checking as well.
3875 Check_Valid_Lvalue_Subscripts
(Prefix
(Expr
));
3877 end Check_Valid_Lvalue_Subscripts
;
3879 ----------------------------------
3880 -- Null_Exclusion_Static_Checks --
3881 ----------------------------------
3883 procedure Null_Exclusion_Static_Checks
(N
: Node_Id
) is
3884 Error_Node
: Node_Id
;
3886 Has_Null
: constant Boolean := Has_Null_Exclusion
(N
);
3887 K
: constant Node_Kind
:= Nkind
(N
);
3892 (Nkind_In
(K
, N_Component_Declaration
,
3893 N_Discriminant_Specification
,
3894 N_Function_Specification
,
3895 N_Object_Declaration
,
3896 N_Parameter_Specification
));
3898 if K
= N_Function_Specification
then
3899 Typ
:= Etype
(Defining_Entity
(N
));
3901 Typ
:= Etype
(Defining_Identifier
(N
));
3905 when N_Component_Declaration
=>
3906 if Present
(Access_Definition
(Component_Definition
(N
))) then
3907 Error_Node
:= Component_Definition
(N
);
3909 Error_Node
:= Subtype_Indication
(Component_Definition
(N
));
3912 when N_Discriminant_Specification
=>
3913 Error_Node
:= Discriminant_Type
(N
);
3915 when N_Function_Specification
=>
3916 Error_Node
:= Result_Definition
(N
);
3918 when N_Object_Declaration
=>
3919 Error_Node
:= Object_Definition
(N
);
3921 when N_Parameter_Specification
=>
3922 Error_Node
:= Parameter_Type
(N
);
3925 raise Program_Error
;
3930 -- Enforce legality rule 3.10 (13): A null exclusion can only be
3931 -- applied to an access [sub]type.
3933 if not Is_Access_Type
(Typ
) then
3935 ("`NOT NULL` allowed only for an access type", Error_Node
);
3937 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
3938 -- be applied to a [sub]type that does not exclude null already.
3940 elsif Can_Never_Be_Null
(Typ
)
3941 and then Comes_From_Source
(Typ
)
3944 ("`NOT NULL` not allowed (& already excludes null)",
3949 -- Check that null-excluding objects are always initialized, except for
3950 -- deferred constants, for which the expression will appear in the full
3953 if K
= N_Object_Declaration
3954 and then No
(Expression
(N
))
3955 and then not Constant_Present
(N
)
3956 and then not No_Initialization
(N
)
3958 -- Add an expression that assigns null. This node is needed by
3959 -- Apply_Compile_Time_Constraint_Error, which will replace this with
3960 -- a Constraint_Error node.
3962 Set_Expression
(N
, Make_Null
(Sloc
(N
)));
3963 Set_Etype
(Expression
(N
), Etype
(Defining_Identifier
(N
)));
3965 Apply_Compile_Time_Constraint_Error
3966 (N
=> Expression
(N
),
3968 "(Ada 2005) null-excluding objects must be initialized??",
3969 Reason
=> CE_Null_Not_Allowed
);
3972 -- Check that a null-excluding component, formal or object is not being
3973 -- assigned a null value. Otherwise generate a warning message and
3974 -- replace Expression (N) by an N_Constraint_Error node.
3976 if K
/= N_Function_Specification
then
3977 Expr
:= Expression
(N
);
3979 if Present
(Expr
) and then Known_Null
(Expr
) then
3981 when N_Component_Declaration |
3982 N_Discriminant_Specification
=>
3983 Apply_Compile_Time_Constraint_Error
3985 Msg
=> "(Ada 2005) null not allowed "
3986 & "in null-excluding components??",
3987 Reason
=> CE_Null_Not_Allowed
);
3989 when N_Object_Declaration
=>
3990 Apply_Compile_Time_Constraint_Error
3992 Msg
=> "(Ada 2005) null not allowed "
3993 & "in null-excluding objects??",
3994 Reason
=> CE_Null_Not_Allowed
);
3996 when N_Parameter_Specification
=>
3997 Apply_Compile_Time_Constraint_Error
3999 Msg
=> "(Ada 2005) null not allowed "
4000 & "in null-excluding formals??",
4001 Reason
=> CE_Null_Not_Allowed
);
4008 end Null_Exclusion_Static_Checks
;
4010 ----------------------------------
4011 -- Conditional_Statements_Begin --
4012 ----------------------------------
4014 procedure Conditional_Statements_Begin
is
4016 Saved_Checks_TOS
:= Saved_Checks_TOS
+ 1;
4018 -- If stack overflows, kill all checks, that way we know to simply reset
4019 -- the number of saved checks to zero on return. This should never occur
4022 if Saved_Checks_TOS
> Saved_Checks_Stack
'Last then
4025 -- In the normal case, we just make a new stack entry saving the current
4026 -- number of saved checks for a later restore.
4029 Saved_Checks_Stack
(Saved_Checks_TOS
) := Num_Saved_Checks
;
4031 if Debug_Flag_CC
then
4032 w
("Conditional_Statements_Begin: Num_Saved_Checks = ",
4036 end Conditional_Statements_Begin
;
4038 --------------------------------
4039 -- Conditional_Statements_End --
4040 --------------------------------
4042 procedure Conditional_Statements_End
is
4044 pragma Assert
(Saved_Checks_TOS
> 0);
4046 -- If the saved checks stack overflowed, then we killed all checks, so
4047 -- setting the number of saved checks back to zero is correct. This
4048 -- should never occur in practice.
4050 if Saved_Checks_TOS
> Saved_Checks_Stack
'Last then
4051 Num_Saved_Checks
:= 0;
4053 -- In the normal case, restore the number of saved checks from the top
4057 Num_Saved_Checks
:= Saved_Checks_Stack
(Saved_Checks_TOS
);
4059 if Debug_Flag_CC
then
4060 w
("Conditional_Statements_End: Num_Saved_Checks = ",
4065 Saved_Checks_TOS
:= Saved_Checks_TOS
- 1;
4066 end Conditional_Statements_End
;
4068 -------------------------
4069 -- Convert_From_Bignum --
4070 -------------------------
4072 function Convert_From_Bignum
(N
: Node_Id
) return Node_Id
is
4073 Loc
: constant Source_Ptr
:= Sloc
(N
);
4076 pragma Assert
(Is_RTE
(Etype
(N
), RE_Bignum
));
4078 -- Construct call From Bignum
4081 Make_Function_Call
(Loc
,
4083 New_Occurrence_Of
(RTE
(RE_From_Bignum
), Loc
),
4084 Parameter_Associations
=> New_List
(Relocate_Node
(N
)));
4085 end Convert_From_Bignum
;
4087 -----------------------
4088 -- Convert_To_Bignum --
4089 -----------------------
4091 function Convert_To_Bignum
(N
: Node_Id
) return Node_Id
is
4092 Loc
: constant Source_Ptr
:= Sloc
(N
);
4095 -- Nothing to do if Bignum already except call Relocate_Node
4097 if Is_RTE
(Etype
(N
), RE_Bignum
) then
4098 return Relocate_Node
(N
);
4100 -- Otherwise construct call to To_Bignum, converting the operand to the
4101 -- required Long_Long_Integer form.
4104 pragma Assert
(Is_Signed_Integer_Type
(Etype
(N
)));
4106 Make_Function_Call
(Loc
,
4108 New_Occurrence_Of
(RTE
(RE_To_Bignum
), Loc
),
4109 Parameter_Associations
=> New_List
(
4110 Convert_To
(Standard_Long_Long_Integer
, Relocate_Node
(N
))));
4112 end Convert_To_Bignum
;
4114 ---------------------
4115 -- Determine_Range --
4116 ---------------------
4118 Cache_Size
: constant := 2 ** 10;
4119 type Cache_Index
is range 0 .. Cache_Size
- 1;
4120 -- Determine size of below cache (power of 2 is more efficient)
4122 Determine_Range_Cache_N
: array (Cache_Index
) of Node_Id
;
4123 Determine_Range_Cache_V
: array (Cache_Index
) of Boolean;
4124 Determine_Range_Cache_Lo
: array (Cache_Index
) of Uint
;
4125 Determine_Range_Cache_Hi
: array (Cache_Index
) of Uint
;
4126 Determine_Range_Cache_Lo_R
: array (Cache_Index
) of Ureal
;
4127 Determine_Range_Cache_Hi_R
: array (Cache_Index
) of Ureal
;
4128 -- The above arrays are used to implement a small direct cache for
4129 -- Determine_Range and Determine_Range_R calls. Because of the way these
4130 -- subprograms recursively traces subexpressions, and because overflow
4131 -- checking calls the routine on the way up the tree, a quadratic behavior
4132 -- can otherwise be encountered in large expressions. The cache entry for
4133 -- node N is stored in the (N mod Cache_Size) entry, and can be validated
4134 -- by checking the actual node value stored there. The Range_Cache_V array
4135 -- records the setting of Assume_Valid for the cache entry.
4137 procedure Determine_Range
4142 Assume_Valid
: Boolean := False)
4144 Typ
: Entity_Id
:= Etype
(N
);
4145 -- Type to use, may get reset to base type for possibly invalid entity
4149 -- Lo and Hi bounds of left operand
4153 -- Lo and Hi bounds of right (or only) operand
4156 -- Temp variable used to hold a bound node
4159 -- High bound of base type of expression
4163 -- Refined values for low and high bounds, after tightening
4166 -- Used in lower level calls to indicate if call succeeded
4168 Cindex
: Cache_Index
;
4169 -- Used to search cache
4174 function OK_Operands
return Boolean;
4175 -- Used for binary operators. Determines the ranges of the left and
4176 -- right operands, and if they are both OK, returns True, and puts
4177 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
4183 function OK_Operands
return Boolean is
4186 (Left_Opnd
(N
), OK1
, Lo_Left
, Hi_Left
, Assume_Valid
);
4193 (Right_Opnd
(N
), OK1
, Lo_Right
, Hi_Right
, Assume_Valid
);
4197 -- Start of processing for Determine_Range
4200 -- Prevent junk warnings by initializing range variables
4207 -- For temporary constants internally generated to remove side effects
4208 -- we must use the corresponding expression to determine the range of
4209 -- the expression. But note that the expander can also generate
4210 -- constants in other cases, including deferred constants.
4212 if Is_Entity_Name
(N
)
4213 and then Nkind
(Parent
(Entity
(N
))) = N_Object_Declaration
4214 and then Ekind
(Entity
(N
)) = E_Constant
4215 and then Is_Internal_Name
(Chars
(Entity
(N
)))
4217 if Present
(Expression
(Parent
(Entity
(N
)))) then
4219 (Expression
(Parent
(Entity
(N
))), OK
, Lo
, Hi
, Assume_Valid
);
4221 elsif Present
(Full_View
(Entity
(N
))) then
4223 (Expression
(Parent
(Full_View
(Entity
(N
)))),
4224 OK
, Lo
, Hi
, Assume_Valid
);
4232 -- If type is not defined, we can't determine its range
4236 -- We don't deal with anything except discrete types
4238 or else not Is_Discrete_Type
(Typ
)
4240 -- Ignore type for which an error has been posted, since range in
4241 -- this case may well be a bogosity deriving from the error. Also
4242 -- ignore if error posted on the reference node.
4244 or else Error_Posted
(N
) or else Error_Posted
(Typ
)
4250 -- For all other cases, we can determine the range
4254 -- If value is compile time known, then the possible range is the one
4255 -- value that we know this expression definitely has.
4257 if Compile_Time_Known_Value
(N
) then
4258 Lo
:= Expr_Value
(N
);
4263 -- Return if already in the cache
4265 Cindex
:= Cache_Index
(N
mod Cache_Size
);
4267 if Determine_Range_Cache_N
(Cindex
) = N
4269 Determine_Range_Cache_V
(Cindex
) = Assume_Valid
4271 Lo
:= Determine_Range_Cache_Lo
(Cindex
);
4272 Hi
:= Determine_Range_Cache_Hi
(Cindex
);
4276 -- Otherwise, start by finding the bounds of the type of the expression,
4277 -- the value cannot be outside this range (if it is, then we have an
4278 -- overflow situation, which is a separate check, we are talking here
4279 -- only about the expression value).
4281 -- First a check, never try to find the bounds of a generic type, since
4282 -- these bounds are always junk values, and it is only valid to look at
4283 -- the bounds in an instance.
4285 if Is_Generic_Type
(Typ
) then
4290 -- First step, change to use base type unless we know the value is valid
4292 if (Is_Entity_Name
(N
) and then Is_Known_Valid
(Entity
(N
)))
4293 or else Assume_No_Invalid_Values
4294 or else Assume_Valid
4298 Typ
:= Underlying_Type
(Base_Type
(Typ
));
4301 -- Retrieve the base type. Handle the case where the base type is a
4302 -- private enumeration type.
4304 Btyp
:= Base_Type
(Typ
);
4306 if Is_Private_Type
(Btyp
) and then Present
(Full_View
(Btyp
)) then
4307 Btyp
:= Full_View
(Btyp
);
4310 -- We use the actual bound unless it is dynamic, in which case use the
4311 -- corresponding base type bound if possible. If we can't get a bound
4312 -- then we figure we can't determine the range (a peculiar case, that
4313 -- perhaps cannot happen, but there is no point in bombing in this
4314 -- optimization circuit.
4316 -- First the low bound
4318 Bound
:= Type_Low_Bound
(Typ
);
4320 if Compile_Time_Known_Value
(Bound
) then
4321 Lo
:= Expr_Value
(Bound
);
4323 elsif Compile_Time_Known_Value
(Type_Low_Bound
(Btyp
)) then
4324 Lo
:= Expr_Value
(Type_Low_Bound
(Btyp
));
4331 -- Now the high bound
4333 Bound
:= Type_High_Bound
(Typ
);
4335 -- We need the high bound of the base type later on, and this should
4336 -- always be compile time known. Again, it is not clear that this
4337 -- can ever be false, but no point in bombing.
4339 if Compile_Time_Known_Value
(Type_High_Bound
(Btyp
)) then
4340 Hbound
:= Expr_Value
(Type_High_Bound
(Btyp
));
4348 -- If we have a static subtype, then that may have a tighter bound so
4349 -- use the upper bound of the subtype instead in this case.
4351 if Compile_Time_Known_Value
(Bound
) then
4352 Hi
:= Expr_Value
(Bound
);
4355 -- We may be able to refine this value in certain situations. If any
4356 -- refinement is possible, then Lor and Hir are set to possibly tighter
4357 -- bounds, and OK1 is set to True.
4361 -- For unary plus, result is limited by range of operand
4365 (Right_Opnd
(N
), OK1
, Lor
, Hir
, Assume_Valid
);
4367 -- For unary minus, determine range of operand, and negate it
4371 (Right_Opnd
(N
), OK1
, Lo_Right
, Hi_Right
, Assume_Valid
);
4378 -- For binary addition, get range of each operand and do the
4379 -- addition to get the result range.
4383 Lor
:= Lo_Left
+ Lo_Right
;
4384 Hir
:= Hi_Left
+ Hi_Right
;
4387 -- Division is tricky. The only case we consider is where the right
4388 -- operand is a positive constant, and in this case we simply divide
4389 -- the bounds of the left operand
4393 if Lo_Right
= Hi_Right
4394 and then Lo_Right
> 0
4396 Lor
:= Lo_Left
/ Lo_Right
;
4397 Hir
:= Hi_Left
/ Lo_Right
;
4403 -- For binary subtraction, get range of each operand and do the worst
4404 -- case subtraction to get the result range.
4406 when N_Op_Subtract
=>
4408 Lor
:= Lo_Left
- Hi_Right
;
4409 Hir
:= Hi_Left
- Lo_Right
;
4412 -- For MOD, if right operand is a positive constant, then result must
4413 -- be in the allowable range of mod results.
4417 if Lo_Right
= Hi_Right
4418 and then Lo_Right
/= 0
4420 if Lo_Right
> 0 then
4422 Hir
:= Lo_Right
- 1;
4424 else -- Lo_Right < 0
4425 Lor
:= Lo_Right
+ 1;
4434 -- For REM, if right operand is a positive constant, then result must
4435 -- be in the allowable range of mod results.
4439 if Lo_Right
= Hi_Right
4440 and then Lo_Right
/= 0
4443 Dval
: constant Uint
:= (abs Lo_Right
) - 1;
4446 -- The sign of the result depends on the sign of the
4447 -- dividend (but not on the sign of the divisor, hence
4448 -- the abs operation above).
4468 -- Attribute reference cases
4470 when N_Attribute_Reference
=>
4471 case Attribute_Name
(N
) is
4473 -- For Pos/Val attributes, we can refine the range using the
4474 -- possible range of values of the attribute expression.
4476 when Name_Pos | Name_Val
=>
4478 (First
(Expressions
(N
)), OK1
, Lor
, Hir
, Assume_Valid
);
4480 -- For Length attribute, use the bounds of the corresponding
4481 -- index type to refine the range.
4485 Atyp
: Entity_Id
:= Etype
(Prefix
(N
));
4493 if Is_Access_Type
(Atyp
) then
4494 Atyp
:= Designated_Type
(Atyp
);
4497 -- For string literal, we know exact value
4499 if Ekind
(Atyp
) = E_String_Literal_Subtype
then
4501 Lo
:= String_Literal_Length
(Atyp
);
4502 Hi
:= String_Literal_Length
(Atyp
);
4506 -- Otherwise check for expression given
4508 if No
(Expressions
(N
)) then
4512 UI_To_Int
(Expr_Value
(First
(Expressions
(N
))));
4515 Indx
:= First_Index
(Atyp
);
4516 for J
in 2 .. Inum
loop
4517 Indx
:= Next_Index
(Indx
);
4520 -- If the index type is a formal type or derived from
4521 -- one, the bounds are not static.
4523 if Is_Generic_Type
(Root_Type
(Etype
(Indx
))) then
4529 (Type_Low_Bound
(Etype
(Indx
)), OK1
, LL
, LU
,
4534 (Type_High_Bound
(Etype
(Indx
)), OK1
, UL
, UU
,
4539 -- The maximum value for Length is the biggest
4540 -- possible gap between the values of the bounds.
4541 -- But of course, this value cannot be negative.
4543 Hir
:= UI_Max
(Uint_0
, UU
- LL
+ 1);
4545 -- For constrained arrays, the minimum value for
4546 -- Length is taken from the actual value of the
4547 -- bounds, since the index will be exactly of this
4550 if Is_Constrained
(Atyp
) then
4551 Lor
:= UI_Max
(Uint_0
, UL
- LU
+ 1);
4553 -- For an unconstrained array, the minimum value
4554 -- for length is always zero.
4563 -- No special handling for other attributes
4564 -- Probably more opportunities exist here???
4571 -- For type conversion from one discrete type to another, we can
4572 -- refine the range using the converted value.
4574 when N_Type_Conversion
=>
4575 Determine_Range
(Expression
(N
), OK1
, Lor
, Hir
, Assume_Valid
);
4577 -- Nothing special to do for all other expression kinds
4585 -- At this stage, if OK1 is true, then we know that the actual result of
4586 -- the computed expression is in the range Lor .. Hir. We can use this
4587 -- to restrict the possible range of results.
4591 -- If the refined value of the low bound is greater than the type
4592 -- low bound, then reset it to the more restrictive value. However,
4593 -- we do NOT do this for the case of a modular type where the
4594 -- possible upper bound on the value is above the base type high
4595 -- bound, because that means the result could wrap.
4598 and then not (Is_Modular_Integer_Type
(Typ
) and then Hir
> Hbound
)
4603 -- Similarly, if the refined value of the high bound is less than the
4604 -- value so far, then reset it to the more restrictive value. Again,
4605 -- we do not do this if the refined low bound is negative for a
4606 -- modular type, since this would wrap.
4609 and then not (Is_Modular_Integer_Type
(Typ
) and then Lor
< Uint_0
)
4615 -- Set cache entry for future call and we are all done
4617 Determine_Range_Cache_N
(Cindex
) := N
;
4618 Determine_Range_Cache_V
(Cindex
) := Assume_Valid
;
4619 Determine_Range_Cache_Lo
(Cindex
) := Lo
;
4620 Determine_Range_Cache_Hi
(Cindex
) := Hi
;
4623 -- If any exception occurs, it means that we have some bug in the compiler,
4624 -- possibly triggered by a previous error, or by some unforeseen peculiar
4625 -- occurrence. However, this is only an optimization attempt, so there is
4626 -- really no point in crashing the compiler. Instead we just decide, too
4627 -- bad, we can't figure out a range in this case after all.
4632 -- Debug flag K disables this behavior (useful for debugging)
4634 if Debug_Flag_K
then
4642 end Determine_Range
;
4644 -----------------------
4645 -- Determine_Range_R --
4646 -----------------------
4648 procedure Determine_Range_R
4653 Assume_Valid
: Boolean := False)
4655 Typ
: Entity_Id
:= Etype
(N
);
4656 -- Type to use, may get reset to base type for possibly invalid entity
4660 -- Lo and Hi bounds of left operand
4664 -- Lo and Hi bounds of right (or only) operand
4667 -- Temp variable used to hold a bound node
4670 -- High bound of base type of expression
4674 -- Refined values for low and high bounds, after tightening
4677 -- Used in lower level calls to indicate if call succeeded
4679 Cindex
: Cache_Index
;
4680 -- Used to search cache
4685 function OK_Operands
return Boolean;
4686 -- Used for binary operators. Determines the ranges of the left and
4687 -- right operands, and if they are both OK, returns True, and puts
4688 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
4690 function Round_Machine
(B
: Ureal
) return Ureal
;
4691 -- B is a real bound. Round it using mode Round_Even.
4697 function OK_Operands
return Boolean is
4700 (Left_Opnd
(N
), OK1
, Lo_Left
, Hi_Left
, Assume_Valid
);
4707 (Right_Opnd
(N
), OK1
, Lo_Right
, Hi_Right
, Assume_Valid
);
4715 function Round_Machine
(B
: Ureal
) return Ureal
is
4717 return Machine
(Typ
, B
, Round_Even
, N
);
4720 -- Start of processing for Determine_Range_R
4723 -- Prevent junk warnings by initializing range variables
4730 -- For temporary constants internally generated to remove side effects
4731 -- we must use the corresponding expression to determine the range of
4732 -- the expression. But note that the expander can also generate
4733 -- constants in other cases, including deferred constants.
4735 if Is_Entity_Name
(N
)
4736 and then Nkind
(Parent
(Entity
(N
))) = N_Object_Declaration
4737 and then Ekind
(Entity
(N
)) = E_Constant
4738 and then Is_Internal_Name
(Chars
(Entity
(N
)))
4740 if Present
(Expression
(Parent
(Entity
(N
)))) then
4742 (Expression
(Parent
(Entity
(N
))), OK
, Lo
, Hi
, Assume_Valid
);
4744 elsif Present
(Full_View
(Entity
(N
))) then
4746 (Expression
(Parent
(Full_View
(Entity
(N
)))),
4747 OK
, Lo
, Hi
, Assume_Valid
);
4756 -- If type is not defined, we can't determine its range
4760 -- We don't deal with anything except IEEE floating-point types
4762 or else not Is_Floating_Point_Type
(Typ
)
4763 or else Float_Rep
(Typ
) /= IEEE_Binary
4765 -- Ignore type for which an error has been posted, since range in
4766 -- this case may well be a bogosity deriving from the error. Also
4767 -- ignore if error posted on the reference node.
4769 or else Error_Posted
(N
) or else Error_Posted
(Typ
)
4775 -- For all other cases, we can determine the range
4779 -- If value is compile time known, then the possible range is the one
4780 -- value that we know this expression definitely has.
4782 if Compile_Time_Known_Value
(N
) then
4783 Lo
:= Expr_Value_R
(N
);
4788 -- Return if already in the cache
4790 Cindex
:= Cache_Index
(N
mod Cache_Size
);
4792 if Determine_Range_Cache_N
(Cindex
) = N
4794 Determine_Range_Cache_V
(Cindex
) = Assume_Valid
4796 Lo
:= Determine_Range_Cache_Lo_R
(Cindex
);
4797 Hi
:= Determine_Range_Cache_Hi_R
(Cindex
);
4801 -- Otherwise, start by finding the bounds of the type of the expression,
4802 -- the value cannot be outside this range (if it is, then we have an
4803 -- overflow situation, which is a separate check, we are talking here
4804 -- only about the expression value).
4806 -- First a check, never try to find the bounds of a generic type, since
4807 -- these bounds are always junk values, and it is only valid to look at
4808 -- the bounds in an instance.
4810 if Is_Generic_Type
(Typ
) then
4815 -- First step, change to use base type unless we know the value is valid
4817 if (Is_Entity_Name
(N
) and then Is_Known_Valid
(Entity
(N
)))
4818 or else Assume_No_Invalid_Values
4819 or else Assume_Valid
4823 Typ
:= Underlying_Type
(Base_Type
(Typ
));
4826 -- Retrieve the base type. Handle the case where the base type is a
4829 Btyp
:= Base_Type
(Typ
);
4831 if Is_Private_Type
(Btyp
) and then Present
(Full_View
(Btyp
)) then
4832 Btyp
:= Full_View
(Btyp
);
4835 -- We use the actual bound unless it is dynamic, in which case use the
4836 -- corresponding base type bound if possible. If we can't get a bound
4837 -- then we figure we can't determine the range (a peculiar case, that
4838 -- perhaps cannot happen, but there is no point in bombing in this
4839 -- optimization circuit).
4841 -- First the low bound
4843 Bound
:= Type_Low_Bound
(Typ
);
4845 if Compile_Time_Known_Value
(Bound
) then
4846 Lo
:= Expr_Value_R
(Bound
);
4848 elsif Compile_Time_Known_Value
(Type_Low_Bound
(Btyp
)) then
4849 Lo
:= Expr_Value_R
(Type_Low_Bound
(Btyp
));
4856 -- Now the high bound
4858 Bound
:= Type_High_Bound
(Typ
);
4860 -- We need the high bound of the base type later on, and this should
4861 -- always be compile time known. Again, it is not clear that this
4862 -- can ever be false, but no point in bombing.
4864 if Compile_Time_Known_Value
(Type_High_Bound
(Btyp
)) then
4865 Hbound
:= Expr_Value_R
(Type_High_Bound
(Btyp
));
4873 -- If we have a static subtype, then that may have a tighter bound so
4874 -- use the upper bound of the subtype instead in this case.
4876 if Compile_Time_Known_Value
(Bound
) then
4877 Hi
:= Expr_Value_R
(Bound
);
4880 -- We may be able to refine this value in certain situations. If any
4881 -- refinement is possible, then Lor and Hir are set to possibly tighter
4882 -- bounds, and OK1 is set to True.
4886 -- For unary plus, result is limited by range of operand
4890 (Right_Opnd
(N
), OK1
, Lor
, Hir
, Assume_Valid
);
4892 -- For unary minus, determine range of operand, and negate it
4896 (Right_Opnd
(N
), OK1
, Lo_Right
, Hi_Right
, Assume_Valid
);
4903 -- For binary addition, get range of each operand and do the
4904 -- addition to get the result range.
4908 Lor
:= Round_Machine
(Lo_Left
+ Lo_Right
);
4909 Hir
:= Round_Machine
(Hi_Left
+ Hi_Right
);
4912 -- For binary subtraction, get range of each operand and do the worst
4913 -- case subtraction to get the result range.
4915 when N_Op_Subtract
=>
4917 Lor
:= Round_Machine
(Lo_Left
- Hi_Right
);
4918 Hir
:= Round_Machine
(Hi_Left
- Lo_Right
);
4921 -- For multiplication, get range of each operand and do the
4922 -- four multiplications to get the result range.
4924 when N_Op_Multiply
=>
4927 M1
: constant Ureal
:= Round_Machine
(Lo_Left
* Lo_Right
);
4928 M2
: constant Ureal
:= Round_Machine
(Lo_Left
* Hi_Right
);
4929 M3
: constant Ureal
:= Round_Machine
(Hi_Left
* Lo_Right
);
4930 M4
: constant Ureal
:= Round_Machine
(Hi_Left
* Hi_Right
);
4932 Lor
:= UR_Min
(UR_Min
(M1
, M2
), UR_Min
(M3
, M4
));
4933 Hir
:= UR_Max
(UR_Max
(M1
, M2
), UR_Max
(M3
, M4
));
4937 -- For division, consider separately the cases where the right
4938 -- operand is positive or negative. Otherwise, the right operand
4939 -- can be arbitrarily close to zero, so the result is likely to
4940 -- be unbounded in one direction, do not attempt to compute it.
4945 -- Right operand is positive
4947 if Lo_Right
> Ureal_0
then
4949 -- If the low bound of the left operand is negative, obtain
4950 -- the overall low bound by dividing it by the smallest
4951 -- value of the right operand, and otherwise by the largest
4952 -- value of the right operand.
4954 if Lo_Left
< Ureal_0
then
4955 Lor
:= Round_Machine
(Lo_Left
/ Lo_Right
);
4957 Lor
:= Round_Machine
(Lo_Left
/ Hi_Right
);
4960 -- If the high bound of the left operand is negative, obtain
4961 -- the overall high bound by dividing it by the largest
4962 -- value of the right operand, and otherwise by the
4963 -- smallest value of the right operand.
4965 if Hi_Left
< Ureal_0
then
4966 Hir
:= Round_Machine
(Hi_Left
/ Hi_Right
);
4968 Hir
:= Round_Machine
(Hi_Left
/ Lo_Right
);
4971 -- Right operand is negative
4973 elsif Hi_Right
< Ureal_0
then
4975 -- If the low bound of the left operand is negative, obtain
4976 -- the overall low bound by dividing it by the largest
4977 -- value of the right operand, and otherwise by the smallest
4978 -- value of the right operand.
4980 if Lo_Left
< Ureal_0
then
4981 Lor
:= Round_Machine
(Lo_Left
/ Hi_Right
);
4983 Lor
:= Round_Machine
(Lo_Left
/ Lo_Right
);
4986 -- If the high bound of the left operand is negative, obtain
4987 -- the overall high bound by dividing it by the smallest
4988 -- value of the right operand, and otherwise by the
4989 -- largest value of the right operand.
4991 if Hi_Left
< Ureal_0
then
4992 Hir
:= Round_Machine
(Hi_Left
/ Lo_Right
);
4994 Hir
:= Round_Machine
(Hi_Left
/ Hi_Right
);
5002 -- For type conversion from one floating-point type to another, we
5003 -- can refine the range using the converted value.
5005 when N_Type_Conversion
=>
5006 Determine_Range_R
(Expression
(N
), OK1
, Lor
, Hir
, Assume_Valid
);
5008 -- Nothing special to do for all other expression kinds
5016 -- At this stage, if OK1 is true, then we know that the actual result of
5017 -- the computed expression is in the range Lor .. Hir. We can use this
5018 -- to restrict the possible range of results.
5022 -- If the refined value of the low bound is greater than the type
5023 -- low bound, then reset it to the more restrictive value.
5029 -- Similarly, if the refined value of the high bound is less than the
5030 -- value so far, then reset it to the more restrictive value.
5037 -- Set cache entry for future call and we are all done
5039 Determine_Range_Cache_N
(Cindex
) := N
;
5040 Determine_Range_Cache_V
(Cindex
) := Assume_Valid
;
5041 Determine_Range_Cache_Lo_R
(Cindex
) := Lo
;
5042 Determine_Range_Cache_Hi_R
(Cindex
) := Hi
;
5045 -- If any exception occurs, it means that we have some bug in the compiler,
5046 -- possibly triggered by a previous error, or by some unforeseen peculiar
5047 -- occurrence. However, this is only an optimization attempt, so there is
5048 -- really no point in crashing the compiler. Instead we just decide, too
5049 -- bad, we can't figure out a range in this case after all.
5054 -- Debug flag K disables this behavior (useful for debugging)
5056 if Debug_Flag_K
then
5064 end Determine_Range_R
;
5066 ------------------------------------
5067 -- Discriminant_Checks_Suppressed --
5068 ------------------------------------
5070 function Discriminant_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5073 if Is_Unchecked_Union
(E
) then
5075 elsif Checks_May_Be_Suppressed
(E
) then
5076 return Is_Check_Suppressed
(E
, Discriminant_Check
);
5080 return Scope_Suppress
.Suppress
(Discriminant_Check
);
5081 end Discriminant_Checks_Suppressed
;
5083 --------------------------------
5084 -- Division_Checks_Suppressed --
5085 --------------------------------
5087 function Division_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5089 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
5090 return Is_Check_Suppressed
(E
, Division_Check
);
5092 return Scope_Suppress
.Suppress
(Division_Check
);
5094 end Division_Checks_Suppressed
;
5096 --------------------------------------
5097 -- Duplicated_Tag_Checks_Suppressed --
5098 --------------------------------------
5100 function Duplicated_Tag_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5102 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
5103 return Is_Check_Suppressed
(E
, Duplicated_Tag_Check
);
5105 return Scope_Suppress
.Suppress
(Duplicated_Tag_Check
);
5107 end Duplicated_Tag_Checks_Suppressed
;
5109 -----------------------------------
5110 -- Elaboration_Checks_Suppressed --
5111 -----------------------------------
5113 function Elaboration_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
5115 -- The complication in this routine is that if we are in the dynamic
5116 -- model of elaboration, we also check All_Checks, since All_Checks
5117 -- does not set Elaboration_Check explicitly.
5120 if Kill_Elaboration_Checks
(E
) then
5123 elsif Checks_May_Be_Suppressed
(E
) then
5124 if Is_Check_Suppressed
(E
, Elaboration_Check
) then
5126 elsif Dynamic_Elaboration_Checks
then
5127 return Is_Check_Suppressed
(E
, All_Checks
);
5134 if Scope_Suppress
.Suppress
(Elaboration_Check
) then
5136 elsif Dynamic_Elaboration_Checks
then
5137 return Scope_Suppress
.Suppress
(All_Checks
);
5141 end Elaboration_Checks_Suppressed
;
5143 ---------------------------
5144 -- Enable_Overflow_Check --
5145 ---------------------------
5147 procedure Enable_Overflow_Check
(N
: Node_Id
) is
5148 Typ
: constant Entity_Id
:= Base_Type
(Etype
(N
));
5149 Mode
: constant Overflow_Mode_Type
:= Overflow_Check_Mode
;
5157 Do_Ovflow_Check
: Boolean;
5160 if Debug_Flag_CC
then
5161 w
("Enable_Overflow_Check for node ", Int
(N
));
5162 Write_Str
(" Source location = ");
5167 -- No check if overflow checks suppressed for type of node
5169 if Overflow_Checks_Suppressed
(Etype
(N
)) then
5172 -- Nothing to do for unsigned integer types, which do not overflow
5174 elsif Is_Modular_Integer_Type
(Typ
) then
5178 -- This is the point at which processing for STRICT mode diverges
5179 -- from processing for MINIMIZED/ELIMINATED modes. This divergence is
5180 -- probably more extreme that it needs to be, but what is going on here
5181 -- is that when we introduced MINIMIZED/ELIMINATED modes, we wanted
5182 -- to leave the processing for STRICT mode untouched. There were
5183 -- two reasons for this. First it avoided any incompatible change of
5184 -- behavior. Second, it guaranteed that STRICT mode continued to be
5187 -- The big difference is that in STRICT mode there is a fair amount of
5188 -- circuitry to try to avoid setting the Do_Overflow_Check flag if we
5189 -- know that no check is needed. We skip all that in the two new modes,
5190 -- since really overflow checking happens over a whole subtree, and we
5191 -- do the corresponding optimizations later on when applying the checks.
5193 if Mode
in Minimized_Or_Eliminated
then
5194 if not (Overflow_Checks_Suppressed
(Etype
(N
)))
5195 and then not (Is_Entity_Name
(N
)
5196 and then Overflow_Checks_Suppressed
(Entity
(N
)))
5198 Activate_Overflow_Check
(N
);
5201 if Debug_Flag_CC
then
5202 w
("Minimized/Eliminated mode");
5208 -- Remainder of processing is for STRICT case, and is unchanged from
5209 -- earlier versions preceding the addition of MINIMIZED/ELIMINATED.
5211 -- Nothing to do if the range of the result is known OK. We skip this
5212 -- for conversions, since the caller already did the check, and in any
5213 -- case the condition for deleting the check for a type conversion is
5216 if Nkind
(N
) /= N_Type_Conversion
then
5217 Determine_Range
(N
, OK
, Lo
, Hi
, Assume_Valid
=> True);
5219 -- Note in the test below that we assume that the range is not OK
5220 -- if a bound of the range is equal to that of the type. That's not
5221 -- quite accurate but we do this for the following reasons:
5223 -- a) The way that Determine_Range works, it will typically report
5224 -- the bounds of the value as being equal to the bounds of the
5225 -- type, because it either can't tell anything more precise, or
5226 -- does not think it is worth the effort to be more precise.
5228 -- b) It is very unusual to have a situation in which this would
5229 -- generate an unnecessary overflow check (an example would be
5230 -- a subtype with a range 0 .. Integer'Last - 1 to which the
5231 -- literal value one is added).
5233 -- c) The alternative is a lot of special casing in this routine
5234 -- which would partially duplicate Determine_Range processing.
5237 Do_Ovflow_Check
:= True;
5239 -- Note that the following checks are quite deliberately > and <
5240 -- rather than >= and <= as explained above.
5242 if Lo
> Expr_Value
(Type_Low_Bound
(Typ
))
5244 Hi
< Expr_Value
(Type_High_Bound
(Typ
))
5246 Do_Ovflow_Check
:= False;
5248 -- Despite the comments above, it is worth dealing specially with
5249 -- division specially. The only case where integer division can
5250 -- overflow is (largest negative number) / (-1). So we will do
5251 -- an extra range analysis to see if this is possible.
5253 elsif Nkind
(N
) = N_Op_Divide
then
5255 (Left_Opnd
(N
), OK
, Lo
, Hi
, Assume_Valid
=> True);
5257 if OK
and then Lo
> Expr_Value
(Type_Low_Bound
(Typ
)) then
5258 Do_Ovflow_Check
:= False;
5262 (Right_Opnd
(N
), OK
, Lo
, Hi
, Assume_Valid
=> True);
5264 if OK
and then (Lo
> Uint_Minus_1
5268 Do_Ovflow_Check
:= False;
5273 -- If no overflow check required, we are done
5275 if not Do_Ovflow_Check
then
5276 if Debug_Flag_CC
then
5277 w
("No overflow check required");
5285 -- If not in optimizing mode, set flag and we are done. We are also done
5286 -- (and just set the flag) if the type is not a discrete type, since it
5287 -- is not worth the effort to eliminate checks for other than discrete
5288 -- types. In addition, we take this same path if we have stored the
5289 -- maximum number of checks possible already (a very unlikely situation,
5290 -- but we do not want to blow up).
5292 if Optimization_Level
= 0
5293 or else not Is_Discrete_Type
(Etype
(N
))
5294 or else Num_Saved_Checks
= Saved_Checks
'Last
5296 Activate_Overflow_Check
(N
);
5298 if Debug_Flag_CC
then
5299 w
("Optimization off");
5305 -- Otherwise evaluate and check the expression
5310 Target_Type
=> Empty
,
5316 if Debug_Flag_CC
then
5317 w
("Called Find_Check");
5321 w
(" Check_Num = ", Chk
);
5322 w
(" Ent = ", Int
(Ent
));
5323 Write_Str
(" Ofs = ");
5328 -- If check is not of form to optimize, then set flag and we are done
5331 Activate_Overflow_Check
(N
);
5335 -- If check is already performed, then return without setting flag
5338 if Debug_Flag_CC
then
5339 w
("Check suppressed!");
5345 -- Here we will make a new entry for the new check
5347 Activate_Overflow_Check
(N
);
5348 Num_Saved_Checks
:= Num_Saved_Checks
+ 1;
5349 Saved_Checks
(Num_Saved_Checks
) :=
5354 Target_Type
=> Empty
);
5356 if Debug_Flag_CC
then
5357 w
("Make new entry, check number = ", Num_Saved_Checks
);
5358 w
(" Entity = ", Int
(Ent
));
5359 Write_Str
(" Offset = ");
5361 w
(" Check_Type = O");
5362 w
(" Target_Type = Empty");
5365 -- If we get an exception, then something went wrong, probably because of
5366 -- an error in the structure of the tree due to an incorrect program. Or
5367 -- it may be a bug in the optimization circuit. In either case the safest
5368 -- thing is simply to set the check flag unconditionally.
5372 Activate_Overflow_Check
(N
);
5374 if Debug_Flag_CC
then
5375 w
(" exception occurred, overflow flag set");
5379 end Enable_Overflow_Check
;
5381 ------------------------
5382 -- Enable_Range_Check --
5383 ------------------------
5385 procedure Enable_Range_Check
(N
: Node_Id
) is
5394 -- Return if unchecked type conversion with range check killed. In this
5395 -- case we never set the flag (that's what Kill_Range_Check is about).
5397 if Nkind
(N
) = N_Unchecked_Type_Conversion
5398 and then Kill_Range_Check
(N
)
5403 -- Do not set range check flag if parent is assignment statement or
5404 -- object declaration with Suppress_Assignment_Checks flag set
5406 if Nkind_In
(Parent
(N
), N_Assignment_Statement
, N_Object_Declaration
)
5407 and then Suppress_Assignment_Checks
(Parent
(N
))
5412 -- Check for various cases where we should suppress the range check
5414 -- No check if range checks suppressed for type of node
5416 if Present
(Etype
(N
)) and then Range_Checks_Suppressed
(Etype
(N
)) then
5419 -- No check if node is an entity name, and range checks are suppressed
5420 -- for this entity, or for the type of this entity.
5422 elsif Is_Entity_Name
(N
)
5423 and then (Range_Checks_Suppressed
(Entity
(N
))
5424 or else Range_Checks_Suppressed
(Etype
(Entity
(N
))))
5428 -- No checks if index of array, and index checks are suppressed for
5429 -- the array object or the type of the array.
5431 elsif Nkind
(Parent
(N
)) = N_Indexed_Component
then
5433 Pref
: constant Node_Id
:= Prefix
(Parent
(N
));
5435 if Is_Entity_Name
(Pref
)
5436 and then Index_Checks_Suppressed
(Entity
(Pref
))
5439 elsif Index_Checks_Suppressed
(Etype
(Pref
)) then
5445 -- Debug trace output
5447 if Debug_Flag_CC
then
5448 w
("Enable_Range_Check for node ", Int
(N
));
5449 Write_Str
(" Source location = ");
5454 -- If not in optimizing mode, set flag and we are done. We are also done
5455 -- (and just set the flag) if the type is not a discrete type, since it
5456 -- is not worth the effort to eliminate checks for other than discrete
5457 -- types. In addition, we take this same path if we have stored the
5458 -- maximum number of checks possible already (a very unlikely situation,
5459 -- but we do not want to blow up).
5461 if Optimization_Level
= 0
5462 or else No
(Etype
(N
))
5463 or else not Is_Discrete_Type
(Etype
(N
))
5464 or else Num_Saved_Checks
= Saved_Checks
'Last
5466 Activate_Range_Check
(N
);
5468 if Debug_Flag_CC
then
5469 w
("Optimization off");
5475 -- Otherwise find out the target type
5479 -- For assignment, use left side subtype
5481 if Nkind
(P
) = N_Assignment_Statement
5482 and then Expression
(P
) = N
5484 Ttyp
:= Etype
(Name
(P
));
5486 -- For indexed component, use subscript subtype
5488 elsif Nkind
(P
) = N_Indexed_Component
then
5495 Atyp
:= Etype
(Prefix
(P
));
5497 if Is_Access_Type
(Atyp
) then
5498 Atyp
:= Designated_Type
(Atyp
);
5500 -- If the prefix is an access to an unconstrained array,
5501 -- perform check unconditionally: it depends on the bounds of
5502 -- an object and we cannot currently recognize whether the test
5503 -- may be redundant.
5505 if not Is_Constrained
(Atyp
) then
5506 Activate_Range_Check
(N
);
5510 -- Ditto if the prefix is an explicit dereference whose designated
5511 -- type is unconstrained.
5513 elsif Nkind
(Prefix
(P
)) = N_Explicit_Dereference
5514 and then not Is_Constrained
(Atyp
)
5516 Activate_Range_Check
(N
);
5520 Indx
:= First_Index
(Atyp
);
5521 Subs
:= First
(Expressions
(P
));
5524 Ttyp
:= Etype
(Indx
);
5533 -- For now, ignore all other cases, they are not so interesting
5536 if Debug_Flag_CC
then
5537 w
(" target type not found, flag set");
5540 Activate_Range_Check
(N
);
5544 -- Evaluate and check the expression
5549 Target_Type
=> Ttyp
,
5555 if Debug_Flag_CC
then
5556 w
("Called Find_Check");
5557 w
("Target_Typ = ", Int
(Ttyp
));
5561 w
(" Check_Num = ", Chk
);
5562 w
(" Ent = ", Int
(Ent
));
5563 Write_Str
(" Ofs = ");
5568 -- If check is not of form to optimize, then set flag and we are done
5571 if Debug_Flag_CC
then
5572 w
(" expression not of optimizable type, flag set");
5575 Activate_Range_Check
(N
);
5579 -- If check is already performed, then return without setting flag
5582 if Debug_Flag_CC
then
5583 w
("Check suppressed!");
5589 -- Here we will make a new entry for the new check
5591 Activate_Range_Check
(N
);
5592 Num_Saved_Checks
:= Num_Saved_Checks
+ 1;
5593 Saved_Checks
(Num_Saved_Checks
) :=
5598 Target_Type
=> Ttyp
);
5600 if Debug_Flag_CC
then
5601 w
("Make new entry, check number = ", Num_Saved_Checks
);
5602 w
(" Entity = ", Int
(Ent
));
5603 Write_Str
(" Offset = ");
5605 w
(" Check_Type = R");
5606 w
(" Target_Type = ", Int
(Ttyp
));
5607 pg
(Union_Id
(Ttyp
));
5610 -- If we get an exception, then something went wrong, probably because of
5611 -- an error in the structure of the tree due to an incorrect program. Or
5612 -- it may be a bug in the optimization circuit. In either case the safest
5613 -- thing is simply to set the check flag unconditionally.
5617 Activate_Range_Check
(N
);
5619 if Debug_Flag_CC
then
5620 w
(" exception occurred, range flag set");
5624 end Enable_Range_Check
;
5630 procedure Ensure_Valid
(Expr
: Node_Id
; Holes_OK
: Boolean := False) is
5631 Typ
: constant Entity_Id
:= Etype
(Expr
);
5634 -- Ignore call if we are not doing any validity checking
5636 if not Validity_Checks_On
then
5639 -- Ignore call if range or validity checks suppressed on entity or type
5641 elsif Range_Or_Validity_Checks_Suppressed
(Expr
) then
5644 -- No check required if expression is from the expander, we assume the
5645 -- expander will generate whatever checks are needed. Note that this is
5646 -- not just an optimization, it avoids infinite recursions.
5648 -- Unchecked conversions must be checked, unless they are initialized
5649 -- scalar values, as in a component assignment in an init proc.
5651 -- In addition, we force a check if Force_Validity_Checks is set
5653 elsif not Comes_From_Source
(Expr
)
5654 and then not Force_Validity_Checks
5655 and then (Nkind
(Expr
) /= N_Unchecked_Type_Conversion
5656 or else Kill_Range_Check
(Expr
))
5660 -- No check required if expression is known to have valid value
5662 elsif Expr_Known_Valid
(Expr
) then
5665 -- Ignore case of enumeration with holes where the flag is set not to
5666 -- worry about holes, since no special validity check is needed
5668 elsif Is_Enumeration_Type
(Typ
)
5669 and then Has_Non_Standard_Rep
(Typ
)
5674 -- No check required on the left-hand side of an assignment
5676 elsif Nkind
(Parent
(Expr
)) = N_Assignment_Statement
5677 and then Expr
= Name
(Parent
(Expr
))
5681 -- No check on a universal real constant. The context will eventually
5682 -- convert it to a machine number for some target type, or report an
5685 elsif Nkind
(Expr
) = N_Real_Literal
5686 and then Etype
(Expr
) = Universal_Real
5690 -- If the expression denotes a component of a packed boolean array,
5691 -- no possible check applies. We ignore the old ACATS chestnuts that
5692 -- involve Boolean range True..True.
5694 -- Note: validity checks are generated for expressions that yield a
5695 -- scalar type, when it is possible to create a value that is outside of
5696 -- the type. If this is a one-bit boolean no such value exists. This is
5697 -- an optimization, and it also prevents compiler blowing up during the
5698 -- elaboration of improperly expanded packed array references.
5700 elsif Nkind
(Expr
) = N_Indexed_Component
5701 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Expr
)))
5702 and then Root_Type
(Etype
(Expr
)) = Standard_Boolean
5706 -- For an expression with actions, we want to insert the validity check
5707 -- on the final Expression.
5709 elsif Nkind
(Expr
) = N_Expression_With_Actions
then
5710 Ensure_Valid
(Expression
(Expr
));
5713 -- An annoying special case. If this is an out parameter of a scalar
5714 -- type, then the value is not going to be accessed, therefore it is
5715 -- inappropriate to do any validity check at the call site.
5718 -- Only need to worry about scalar types
5720 if Is_Scalar_Type
(Typ
) then
5730 -- Find actual argument (which may be a parameter association)
5731 -- and the parent of the actual argument (the call statement)
5736 if Nkind
(P
) = N_Parameter_Association
then
5741 -- Only need to worry if we are argument of a procedure call
5742 -- since functions don't have out parameters. If this is an
5743 -- indirect or dispatching call, get signature from the
5746 if Nkind
(P
) = N_Procedure_Call_Statement
then
5747 L
:= Parameter_Associations
(P
);
5749 if Is_Entity_Name
(Name
(P
)) then
5750 E
:= Entity
(Name
(P
));
5752 pragma Assert
(Nkind
(Name
(P
)) = N_Explicit_Dereference
);
5753 E
:= Etype
(Name
(P
));
5756 -- Only need to worry if there are indeed actuals, and if
5757 -- this could be a procedure call, otherwise we cannot get a
5758 -- match (either we are not an argument, or the mode of the
5759 -- formal is not OUT). This test also filters out the
5762 if Is_Non_Empty_List
(L
) and then Is_Subprogram
(E
) then
5764 -- This is the loop through parameters, looking for an
5765 -- OUT parameter for which we are the argument.
5767 F
:= First_Formal
(E
);
5769 while Present
(F
) loop
5770 if Ekind
(F
) = E_Out_Parameter
and then A
= N
then
5783 -- If this is a boolean expression, only its elementary operands need
5784 -- checking: if they are valid, a boolean or short-circuit operation
5785 -- with them will be valid as well.
5787 if Base_Type
(Typ
) = Standard_Boolean
5789 (Nkind
(Expr
) in N_Op
or else Nkind
(Expr
) in N_Short_Circuit
)
5794 -- If we fall through, a validity check is required
5796 Insert_Valid_Check
(Expr
);
5798 if Is_Entity_Name
(Expr
)
5799 and then Safe_To_Capture_Value
(Expr
, Entity
(Expr
))
5801 Set_Is_Known_Valid
(Entity
(Expr
));
5805 ----------------------
5806 -- Expr_Known_Valid --
5807 ----------------------
5809 function Expr_Known_Valid
(Expr
: Node_Id
) return Boolean is
5810 Typ
: constant Entity_Id
:= Etype
(Expr
);
5813 -- Non-scalar types are always considered valid, since they never give
5814 -- rise to the issues of erroneous or bounded error behavior that are
5815 -- the concern. In formal reference manual terms the notion of validity
5816 -- only applies to scalar types. Note that even when packed arrays are
5817 -- represented using modular types, they are still arrays semantically,
5818 -- so they are also always valid (in particular, the unused bits can be
5819 -- random rubbish without affecting the validity of the array value).
5821 if not Is_Scalar_Type
(Typ
) or else Is_Packed_Array_Impl_Type
(Typ
) then
5824 -- If no validity checking, then everything is considered valid
5826 elsif not Validity_Checks_On
then
5829 -- Floating-point types are considered valid unless floating-point
5830 -- validity checks have been specifically turned on.
5832 elsif Is_Floating_Point_Type
(Typ
)
5833 and then not Validity_Check_Floating_Point
5837 -- If the expression is the value of an object that is known to be
5838 -- valid, then clearly the expression value itself is valid.
5840 elsif Is_Entity_Name
(Expr
)
5841 and then Is_Known_Valid
(Entity
(Expr
))
5843 -- Exclude volatile variables
5845 and then not Treat_As_Volatile
(Entity
(Expr
))
5849 -- References to discriminants are always considered valid. The value
5850 -- of a discriminant gets checked when the object is built. Within the
5851 -- record, we consider it valid, and it is important to do so, since
5852 -- otherwise we can try to generate bogus validity checks which
5853 -- reference discriminants out of scope. Discriminants of concurrent
5854 -- types are excluded for the same reason.
5856 elsif Is_Entity_Name
(Expr
)
5857 and then Denotes_Discriminant
(Expr
, Check_Concurrent
=> True)
5861 -- If the type is one for which all values are known valid, then we are
5862 -- sure that the value is valid except in the slightly odd case where
5863 -- the expression is a reference to a variable whose size has been
5864 -- explicitly set to a value greater than the object size.
5866 elsif Is_Known_Valid
(Typ
) then
5867 if Is_Entity_Name
(Expr
)
5868 and then Ekind
(Entity
(Expr
)) = E_Variable
5869 and then Esize
(Entity
(Expr
)) > Esize
(Typ
)
5876 -- Integer and character literals always have valid values, where
5877 -- appropriate these will be range checked in any case.
5879 elsif Nkind_In
(Expr
, N_Integer_Literal
, N_Character_Literal
) then
5882 -- Real literals are assumed to be valid in VM targets
5884 elsif VM_Target
/= No_VM
and then Nkind
(Expr
) = N_Real_Literal
then
5887 -- If we have a type conversion or a qualification of a known valid
5888 -- value, then the result will always be valid.
5890 elsif Nkind_In
(Expr
, N_Type_Conversion
, N_Qualified_Expression
) then
5891 return Expr_Known_Valid
(Expression
(Expr
));
5893 -- Case of expression is a non-floating-point operator. In this case we
5894 -- can assume the result is valid the generated code for the operator
5895 -- will include whatever checks are needed (e.g. range checks) to ensure
5896 -- validity. This assumption does not hold for the floating-point case,
5897 -- since floating-point operators can generate Infinite or NaN results
5898 -- which are considered invalid.
5900 -- Historical note: in older versions, the exemption of floating-point
5901 -- types from this assumption was done only in cases where the parent
5902 -- was an assignment, function call or parameter association. Presumably
5903 -- the idea was that in other contexts, the result would be checked
5904 -- elsewhere, but this list of cases was missing tests (at least the
5905 -- N_Object_Declaration case, as shown by a reported missing validity
5906 -- check), and it is not clear why function calls but not procedure
5907 -- calls were tested for. It really seems more accurate and much
5908 -- safer to recognize that expressions which are the result of a
5909 -- floating-point operator can never be assumed to be valid.
5911 elsif Nkind
(Expr
) in N_Op
and then not Is_Floating_Point_Type
(Typ
) then
5914 -- The result of a membership test is always valid, since it is true or
5915 -- false, there are no other possibilities.
5917 elsif Nkind
(Expr
) in N_Membership_Test
then
5920 -- For all other cases, we do not know the expression is valid
5925 end Expr_Known_Valid
;
5931 procedure Find_Check
5933 Check_Type
: Character;
5934 Target_Type
: Entity_Id
;
5935 Entry_OK
: out Boolean;
5936 Check_Num
: out Nat
;
5937 Ent
: out Entity_Id
;
5940 function Within_Range_Of
5941 (Target_Type
: Entity_Id
;
5942 Check_Type
: Entity_Id
) return Boolean;
5943 -- Given a requirement for checking a range against Target_Type, and
5944 -- and a range Check_Type against which a check has already been made,
5945 -- determines if the check against check type is sufficient to ensure
5946 -- that no check against Target_Type is required.
5948 ---------------------
5949 -- Within_Range_Of --
5950 ---------------------
5952 function Within_Range_Of
5953 (Target_Type
: Entity_Id
;
5954 Check_Type
: Entity_Id
) return Boolean
5957 if Target_Type
= Check_Type
then
5962 Tlo
: constant Node_Id
:= Type_Low_Bound
(Target_Type
);
5963 Thi
: constant Node_Id
:= Type_High_Bound
(Target_Type
);
5964 Clo
: constant Node_Id
:= Type_Low_Bound
(Check_Type
);
5965 Chi
: constant Node_Id
:= Type_High_Bound
(Check_Type
);
5969 or else (Compile_Time_Known_Value
(Tlo
)
5971 Compile_Time_Known_Value
(Clo
)
5973 Expr_Value
(Clo
) >= Expr_Value
(Tlo
)))
5976 or else (Compile_Time_Known_Value
(Thi
)
5978 Compile_Time_Known_Value
(Chi
)
5980 Expr_Value
(Chi
) <= Expr_Value
(Clo
)))
5988 end Within_Range_Of
;
5990 -- Start of processing for Find_Check
5993 -- Establish default, in case no entry is found
5997 -- Case of expression is simple entity reference
5999 if Is_Entity_Name
(Expr
) then
6000 Ent
:= Entity
(Expr
);
6003 -- Case of expression is entity + known constant
6005 elsif Nkind
(Expr
) = N_Op_Add
6006 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
6007 and then Is_Entity_Name
(Left_Opnd
(Expr
))
6009 Ent
:= Entity
(Left_Opnd
(Expr
));
6010 Ofs
:= Expr_Value
(Right_Opnd
(Expr
));
6012 -- Case of expression is entity - known constant
6014 elsif Nkind
(Expr
) = N_Op_Subtract
6015 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
6016 and then Is_Entity_Name
(Left_Opnd
(Expr
))
6018 Ent
:= Entity
(Left_Opnd
(Expr
));
6019 Ofs
:= UI_Negate
(Expr_Value
(Right_Opnd
(Expr
)));
6021 -- Any other expression is not of the right form
6030 -- Come here with expression of appropriate form, check if entity is an
6031 -- appropriate one for our purposes.
6033 if (Ekind
(Ent
) = E_Variable
6034 or else Is_Constant_Object
(Ent
))
6035 and then not Is_Library_Level_Entity
(Ent
)
6043 -- See if there is matching check already
6045 for J
in reverse 1 .. Num_Saved_Checks
loop
6047 SC
: Saved_Check
renames Saved_Checks
(J
);
6049 if SC
.Killed
= False
6050 and then SC
.Entity
= Ent
6051 and then SC
.Offset
= Ofs
6052 and then SC
.Check_Type
= Check_Type
6053 and then Within_Range_Of
(Target_Type
, SC
.Target_Type
)
6061 -- If we fall through entry was not found
6066 ---------------------------------
6067 -- Generate_Discriminant_Check --
6068 ---------------------------------
6070 -- Note: the code for this procedure is derived from the
6071 -- Emit_Discriminant_Check Routine in trans.c.
6073 procedure Generate_Discriminant_Check
(N
: Node_Id
) is
6074 Loc
: constant Source_Ptr
:= Sloc
(N
);
6075 Pref
: constant Node_Id
:= Prefix
(N
);
6076 Sel
: constant Node_Id
:= Selector_Name
(N
);
6078 Orig_Comp
: constant Entity_Id
:=
6079 Original_Record_Component
(Entity
(Sel
));
6080 -- The original component to be checked
6082 Discr_Fct
: constant Entity_Id
:=
6083 Discriminant_Checking_Func
(Orig_Comp
);
6084 -- The discriminant checking function
6087 -- One discriminant to be checked in the type
6089 Real_Discr
: Entity_Id
;
6090 -- Actual discriminant in the call
6092 Pref_Type
: Entity_Id
;
6093 -- Type of relevant prefix (ignoring private/access stuff)
6096 -- List of arguments for function call
6099 -- Keep track of the formal corresponding to the actual we build for
6100 -- each discriminant, in order to be able to perform the necessary type
6104 -- Selected component reference for checking function argument
6107 Pref_Type
:= Etype
(Pref
);
6109 -- Force evaluation of the prefix, so that it does not get evaluated
6110 -- twice (once for the check, once for the actual reference). Such a
6111 -- double evaluation is always a potential source of inefficiency, and
6112 -- is functionally incorrect in the volatile case, or when the prefix
6113 -- may have side-effects. A non-volatile entity or a component of a
6114 -- non-volatile entity requires no evaluation.
6116 if Is_Entity_Name
(Pref
) then
6117 if Treat_As_Volatile
(Entity
(Pref
)) then
6118 Force_Evaluation
(Pref
, Name_Req
=> True);
6121 elsif Treat_As_Volatile
(Etype
(Pref
)) then
6122 Force_Evaluation
(Pref
, Name_Req
=> True);
6124 elsif Nkind
(Pref
) = N_Selected_Component
6125 and then Is_Entity_Name
(Prefix
(Pref
))
6130 Force_Evaluation
(Pref
, Name_Req
=> True);
6133 -- For a tagged type, use the scope of the original component to
6134 -- obtain the type, because ???
6136 if Is_Tagged_Type
(Scope
(Orig_Comp
)) then
6137 Pref_Type
:= Scope
(Orig_Comp
);
6139 -- For an untagged derived type, use the discriminants of the parent
6140 -- which have been renamed in the derivation, possibly by a one-to-many
6141 -- discriminant constraint. For untagged type, initially get the Etype
6145 if Is_Derived_Type
(Pref_Type
)
6146 and then Number_Discriminants
(Pref_Type
) /=
6147 Number_Discriminants
(Etype
(Base_Type
(Pref_Type
)))
6149 Pref_Type
:= Etype
(Base_Type
(Pref_Type
));
6153 -- We definitely should have a checking function, This routine should
6154 -- not be called if no discriminant checking function is present.
6156 pragma Assert
(Present
(Discr_Fct
));
6158 -- Create the list of the actual parameters for the call. This list
6159 -- is the list of the discriminant fields of the record expression to
6160 -- be discriminant checked.
6163 Formal
:= First_Formal
(Discr_Fct
);
6164 Discr
:= First_Discriminant
(Pref_Type
);
6165 while Present
(Discr
) loop
6167 -- If we have a corresponding discriminant field, and a parent
6168 -- subtype is present, then we want to use the corresponding
6169 -- discriminant since this is the one with the useful value.
6171 if Present
(Corresponding_Discriminant
(Discr
))
6172 and then Ekind
(Pref_Type
) = E_Record_Type
6173 and then Present
(Parent_Subtype
(Pref_Type
))
6175 Real_Discr
:= Corresponding_Discriminant
(Discr
);
6177 Real_Discr
:= Discr
;
6180 -- Construct the reference to the discriminant
6183 Make_Selected_Component
(Loc
,
6185 Unchecked_Convert_To
(Pref_Type
,
6186 Duplicate_Subexpr
(Pref
)),
6187 Selector_Name
=> New_Occurrence_Of
(Real_Discr
, Loc
));
6189 -- Manually analyze and resolve this selected component. We really
6190 -- want it just as it appears above, and do not want the expander
6191 -- playing discriminal games etc with this reference. Then we append
6192 -- the argument to the list we are gathering.
6194 Set_Etype
(Scomp
, Etype
(Real_Discr
));
6195 Set_Analyzed
(Scomp
, True);
6196 Append_To
(Args
, Convert_To
(Etype
(Formal
), Scomp
));
6198 Next_Formal_With_Extras
(Formal
);
6199 Next_Discriminant
(Discr
);
6202 -- Now build and insert the call
6205 Make_Raise_Constraint_Error
(Loc
,
6207 Make_Function_Call
(Loc
,
6208 Name
=> New_Occurrence_Of
(Discr_Fct
, Loc
),
6209 Parameter_Associations
=> Args
),
6210 Reason
=> CE_Discriminant_Check_Failed
));
6211 end Generate_Discriminant_Check
;
6213 ---------------------------
6214 -- Generate_Index_Checks --
6215 ---------------------------
6217 procedure Generate_Index_Checks
(N
: Node_Id
) is
6219 function Entity_Of_Prefix
return Entity_Id
;
6220 -- Returns the entity of the prefix of N (or Empty if not found)
6222 ----------------------
6223 -- Entity_Of_Prefix --
6224 ----------------------
6226 function Entity_Of_Prefix
return Entity_Id
is
6231 while not Is_Entity_Name
(P
) loop
6232 if not Nkind_In
(P
, N_Selected_Component
,
6233 N_Indexed_Component
)
6242 end Entity_Of_Prefix
;
6246 Loc
: constant Source_Ptr
:= Sloc
(N
);
6247 A
: constant Node_Id
:= Prefix
(N
);
6248 A_Ent
: constant Entity_Id
:= Entity_Of_Prefix
;
6251 -- Start of processing for Generate_Index_Checks
6254 -- Ignore call if the prefix is not an array since we have a serious
6255 -- error in the sources. Ignore it also if index checks are suppressed
6256 -- for array object or type.
6258 if not Is_Array_Type
(Etype
(A
))
6259 or else (Present
(A_Ent
) and then Index_Checks_Suppressed
(A_Ent
))
6260 or else Index_Checks_Suppressed
(Etype
(A
))
6264 -- The indexed component we are dealing with contains 'Loop_Entry in its
6265 -- prefix. This case arises when analysis has determined that constructs
6268 -- Prefix'Loop_Entry (Expr)
6269 -- Prefix'Loop_Entry (Expr1, Expr2, ... ExprN)
6271 -- require rewriting for error detection purposes. A side effect of this
6272 -- action is the generation of index checks that mention 'Loop_Entry.
6273 -- Delay the generation of the check until 'Loop_Entry has been properly
6274 -- expanded. This is done in Expand_Loop_Entry_Attributes.
6276 elsif Nkind
(Prefix
(N
)) = N_Attribute_Reference
6277 and then Attribute_Name
(Prefix
(N
)) = Name_Loop_Entry
6282 -- Generate a raise of constraint error with the appropriate reason and
6283 -- a condition of the form:
6285 -- Base_Type (Sub) not in Array'Range (Subscript)
6287 -- Note that the reason we generate the conversion to the base type here
6288 -- is that we definitely want the range check to take place, even if it
6289 -- looks like the subtype is OK. Optimization considerations that allow
6290 -- us to omit the check have already been taken into account in the
6291 -- setting of the Do_Range_Check flag earlier on.
6293 Sub
:= First
(Expressions
(N
));
6295 -- Handle string literals
6297 if Ekind
(Etype
(A
)) = E_String_Literal_Subtype
then
6298 if Do_Range_Check
(Sub
) then
6299 Set_Do_Range_Check
(Sub
, False);
6301 -- For string literals we obtain the bounds of the string from the
6302 -- associated subtype.
6305 Make_Raise_Constraint_Error
(Loc
,
6309 Convert_To
(Base_Type
(Etype
(Sub
)),
6310 Duplicate_Subexpr_Move_Checks
(Sub
)),
6312 Make_Attribute_Reference
(Loc
,
6313 Prefix
=> New_Occurrence_Of
(Etype
(A
), Loc
),
6314 Attribute_Name
=> Name_Range
)),
6315 Reason
=> CE_Index_Check_Failed
));
6322 A_Idx
: Node_Id
:= Empty
;
6329 A_Idx
:= First_Index
(Etype
(A
));
6331 while Present
(Sub
) loop
6332 if Do_Range_Check
(Sub
) then
6333 Set_Do_Range_Check
(Sub
, False);
6335 -- Force evaluation except for the case of a simple name of
6336 -- a non-volatile entity.
6338 if not Is_Entity_Name
(Sub
)
6339 or else Treat_As_Volatile
(Entity
(Sub
))
6341 Force_Evaluation
(Sub
);
6344 if Nkind
(A_Idx
) = N_Range
then
6347 elsif Nkind
(A_Idx
) = N_Identifier
6348 or else Nkind
(A_Idx
) = N_Expanded_Name
6350 A_Range
:= Scalar_Range
(Entity
(A_Idx
));
6352 else pragma Assert
(Nkind
(A_Idx
) = N_Subtype_Indication
);
6353 A_Range
:= Range_Expression
(Constraint
(A_Idx
));
6356 -- For array objects with constant bounds we can generate
6357 -- the index check using the bounds of the type of the index
6360 and then Ekind
(A_Ent
) = E_Variable
6361 and then Is_Constant_Bound
(Low_Bound
(A_Range
))
6362 and then Is_Constant_Bound
(High_Bound
(A_Range
))
6365 Make_Attribute_Reference
(Loc
,
6367 New_Occurrence_Of
(Etype
(A_Idx
), Loc
),
6368 Attribute_Name
=> Name_Range
);
6370 -- For arrays with non-constant bounds we cannot generate
6371 -- the index check using the bounds of the type of the index
6372 -- since it may reference discriminants of some enclosing
6373 -- type. We obtain the bounds directly from the prefix
6380 Num
:= New_List
(Make_Integer_Literal
(Loc
, Ind
));
6384 Make_Attribute_Reference
(Loc
,
6386 Duplicate_Subexpr_Move_Checks
(A
, Name_Req
=> True),
6387 Attribute_Name
=> Name_Range
,
6388 Expressions
=> Num
);
6392 Make_Raise_Constraint_Error
(Loc
,
6396 Convert_To
(Base_Type
(Etype
(Sub
)),
6397 Duplicate_Subexpr_Move_Checks
(Sub
)),
6398 Right_Opnd
=> Range_N
),
6399 Reason
=> CE_Index_Check_Failed
));
6402 A_Idx
:= Next_Index
(A_Idx
);
6408 end Generate_Index_Checks
;
6410 --------------------------
6411 -- Generate_Range_Check --
6412 --------------------------
6414 procedure Generate_Range_Check
6416 Target_Type
: Entity_Id
;
6417 Reason
: RT_Exception_Code
)
6419 Loc
: constant Source_Ptr
:= Sloc
(N
);
6420 Source_Type
: constant Entity_Id
:= Etype
(N
);
6421 Source_Base_Type
: constant Entity_Id
:= Base_Type
(Source_Type
);
6422 Target_Base_Type
: constant Entity_Id
:= Base_Type
(Target_Type
);
6424 procedure Convert_And_Check_Range
;
6425 -- Convert the conversion operand to the target base type and save in
6426 -- a temporary. Then check the converted value against the range of the
6429 -----------------------------
6430 -- Convert_And_Check_Range --
6431 -----------------------------
6433 procedure Convert_And_Check_Range
is
6434 Tnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', N
);
6437 -- We make a temporary to hold the value of the converted value
6438 -- (converted to the base type), and then do the test against this
6439 -- temporary. The conversion itself is replaced by an occurrence of
6440 -- Tnn and followed by the explicit range check. Note that checks
6441 -- are suppressed for this code, since we don't want a recursive
6442 -- range check popping up.
6444 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
6445 -- [constraint_error when Tnn not in Target_Type]
6447 Insert_Actions
(N
, New_List
(
6448 Make_Object_Declaration
(Loc
,
6449 Defining_Identifier
=> Tnn
,
6450 Object_Definition
=> New_Occurrence_Of
(Target_Base_Type
, Loc
),
6451 Constant_Present
=> True,
6453 Make_Type_Conversion
(Loc
,
6454 Subtype_Mark
=> New_Occurrence_Of
(Target_Base_Type
, Loc
),
6455 Expression
=> Duplicate_Subexpr
(N
))),
6457 Make_Raise_Constraint_Error
(Loc
,
6460 Left_Opnd
=> New_Occurrence_Of
(Tnn
, Loc
),
6461 Right_Opnd
=> New_Occurrence_Of
(Target_Type
, Loc
)),
6463 Suppress
=> All_Checks
);
6465 Rewrite
(N
, New_Occurrence_Of
(Tnn
, Loc
));
6467 -- Set the type of N, because the declaration for Tnn might not
6468 -- be analyzed yet, as is the case if N appears within a record
6469 -- declaration, as a discriminant constraint or expression.
6471 Set_Etype
(N
, Target_Base_Type
);
6472 end Convert_And_Check_Range
;
6474 -- Start of processing for Generate_Range_Check
6477 -- First special case, if the source type is already within the range
6478 -- of the target type, then no check is needed (probably we should have
6479 -- stopped Do_Range_Check from being set in the first place, but better
6480 -- late than never in preventing junk code and junk flag settings.
6482 if In_Subrange_Of
(Source_Type
, Target_Type
)
6484 -- We do NOT apply this if the source node is a literal, since in this
6485 -- case the literal has already been labeled as having the subtype of
6489 (Nkind_In
(N
, N_Integer_Literal
, N_Real_Literal
, N_Character_Literal
)
6492 and then Ekind
(Entity
(N
)) = E_Enumeration_Literal
))
6494 Set_Do_Range_Check
(N
, False);
6498 -- Here a check is needed. If the expander is not active, or if we are
6499 -- in GNATProve mode, then simply set the Do_Range_Check flag and we
6500 -- are done. In both these cases, we just want to see the range check
6501 -- flag set, we do not want to generate the explicit range check code.
6503 if GNATprove_Mode
or else not Expander_Active
then
6504 Set_Do_Range_Check
(N
, True);
6508 -- Here we will generate an explicit range check, so we don't want to
6509 -- set the Do_Range check flag, since the range check is taken care of
6510 -- by the code we will generate.
6512 Set_Do_Range_Check
(N
, False);
6514 -- Force evaluation of the node, so that it does not get evaluated twice
6515 -- (once for the check, once for the actual reference). Such a double
6516 -- evaluation is always a potential source of inefficiency, and is
6517 -- functionally incorrect in the volatile case.
6519 if not Is_Entity_Name
(N
) or else Treat_As_Volatile
(Entity
(N
)) then
6520 Force_Evaluation
(N
);
6523 -- The easiest case is when Source_Base_Type and Target_Base_Type are
6524 -- the same since in this case we can simply do a direct check of the
6525 -- value of N against the bounds of Target_Type.
6527 -- [constraint_error when N not in Target_Type]
6529 -- Note: this is by far the most common case, for example all cases of
6530 -- checks on the RHS of assignments are in this category, but not all
6531 -- cases are like this. Notably conversions can involve two types.
6533 if Source_Base_Type
= Target_Base_Type
then
6535 -- Insert the explicit range check. Note that we suppress checks for
6536 -- this code, since we don't want a recursive range check popping up.
6539 Make_Raise_Constraint_Error
(Loc
,
6542 Left_Opnd
=> Duplicate_Subexpr
(N
),
6543 Right_Opnd
=> New_Occurrence_Of
(Target_Type
, Loc
)),
6545 Suppress
=> All_Checks
);
6547 -- Next test for the case where the target type is within the bounds
6548 -- of the base type of the source type, since in this case we can
6549 -- simply convert these bounds to the base type of T to do the test.
6551 -- [constraint_error when N not in
6552 -- Source_Base_Type (Target_Type'First)
6554 -- Source_Base_Type(Target_Type'Last))]
6556 -- The conversions will always work and need no check
6558 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
6559 -- of converting from an enumeration value to an integer type, such as
6560 -- occurs for the case of generating a range check on Enum'Val(Exp)
6561 -- (which used to be handled by gigi). This is OK, since the conversion
6562 -- itself does not require a check.
6564 elsif In_Subrange_Of
(Target_Type
, Source_Base_Type
) then
6566 -- Insert the explicit range check. Note that we suppress checks for
6567 -- this code, since we don't want a recursive range check popping up.
6569 if Is_Discrete_Type
(Source_Base_Type
)
6571 Is_Discrete_Type
(Target_Base_Type
)
6574 Make_Raise_Constraint_Error
(Loc
,
6577 Left_Opnd
=> Duplicate_Subexpr
(N
),
6582 Unchecked_Convert_To
(Source_Base_Type
,
6583 Make_Attribute_Reference
(Loc
,
6585 New_Occurrence_Of
(Target_Type
, Loc
),
6586 Attribute_Name
=> Name_First
)),
6589 Unchecked_Convert_To
(Source_Base_Type
,
6590 Make_Attribute_Reference
(Loc
,
6592 New_Occurrence_Of
(Target_Type
, Loc
),
6593 Attribute_Name
=> Name_Last
)))),
6595 Suppress
=> All_Checks
);
6597 -- For conversions involving at least one type that is not discrete,
6598 -- first convert to target type and then generate the range check.
6599 -- This avoids problems with values that are close to a bound of the
6600 -- target type that would fail a range check when done in a larger
6601 -- source type before converting but would pass if converted with
6602 -- rounding and then checked (such as in float-to-float conversions).
6605 Convert_And_Check_Range
;
6608 -- Note that at this stage we now that the Target_Base_Type is not in
6609 -- the range of the Source_Base_Type (since even the Target_Type itself
6610 -- is not in this range). It could still be the case that Source_Type is
6611 -- in range of the target base type since we have not checked that case.
6613 -- If that is the case, we can freely convert the source to the target,
6614 -- and then test the target result against the bounds.
6616 elsif In_Subrange_Of
(Source_Type
, Target_Base_Type
) then
6617 Convert_And_Check_Range
;
6619 -- At this stage, we know that we have two scalar types, which are
6620 -- directly convertible, and where neither scalar type has a base
6621 -- range that is in the range of the other scalar type.
6623 -- The only way this can happen is with a signed and unsigned type.
6624 -- So test for these two cases:
6627 -- Case of the source is unsigned and the target is signed
6629 if Is_Unsigned_Type
(Source_Base_Type
)
6630 and then not Is_Unsigned_Type
(Target_Base_Type
)
6632 -- If the source is unsigned and the target is signed, then we
6633 -- know that the source is not shorter than the target (otherwise
6634 -- the source base type would be in the target base type range).
6636 -- In other words, the unsigned type is either the same size as
6637 -- the target, or it is larger. It cannot be smaller.
6640 (Esize
(Source_Base_Type
) >= Esize
(Target_Base_Type
));
6642 -- We only need to check the low bound if the low bound of the
6643 -- target type is non-negative. If the low bound of the target
6644 -- type is negative, then we know that we will fit fine.
6646 -- If the high bound of the target type is negative, then we
6647 -- know we have a constraint error, since we can't possibly
6648 -- have a negative source.
6650 -- With these two checks out of the way, we can do the check
6651 -- using the source type safely
6653 -- This is definitely the most annoying case.
6655 -- [constraint_error
6656 -- when (Target_Type'First >= 0
6658 -- N < Source_Base_Type (Target_Type'First))
6659 -- or else Target_Type'Last < 0
6660 -- or else N > Source_Base_Type (Target_Type'Last)];
6662 -- We turn off all checks since we know that the conversions
6663 -- will work fine, given the guards for negative values.
6666 Make_Raise_Constraint_Error
(Loc
,
6672 Left_Opnd
=> Make_Op_Ge
(Loc
,
6674 Make_Attribute_Reference
(Loc
,
6676 New_Occurrence_Of
(Target_Type
, Loc
),
6677 Attribute_Name
=> Name_First
),
6678 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
6682 Left_Opnd
=> Duplicate_Subexpr
(N
),
6684 Convert_To
(Source_Base_Type
,
6685 Make_Attribute_Reference
(Loc
,
6687 New_Occurrence_Of
(Target_Type
, Loc
),
6688 Attribute_Name
=> Name_First
)))),
6693 Make_Attribute_Reference
(Loc
,
6694 Prefix
=> New_Occurrence_Of
(Target_Type
, Loc
),
6695 Attribute_Name
=> Name_Last
),
6696 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
))),
6700 Left_Opnd
=> Duplicate_Subexpr
(N
),
6702 Convert_To
(Source_Base_Type
,
6703 Make_Attribute_Reference
(Loc
,
6704 Prefix
=> New_Occurrence_Of
(Target_Type
, Loc
),
6705 Attribute_Name
=> Name_Last
)))),
6708 Suppress
=> All_Checks
);
6710 -- Only remaining possibility is that the source is signed and
6711 -- the target is unsigned.
6714 pragma Assert
(not Is_Unsigned_Type
(Source_Base_Type
)
6715 and then Is_Unsigned_Type
(Target_Base_Type
));
6717 -- If the source is signed and the target is unsigned, then we
6718 -- know that the target is not shorter than the source (otherwise
6719 -- the target base type would be in the source base type range).
6721 -- In other words, the unsigned type is either the same size as
6722 -- the target, or it is larger. It cannot be smaller.
6724 -- Clearly we have an error if the source value is negative since
6725 -- no unsigned type can have negative values. If the source type
6726 -- is non-negative, then the check can be done using the target
6729 -- Tnn : constant Target_Base_Type (N) := Target_Type;
6731 -- [constraint_error
6732 -- when N < 0 or else Tnn not in Target_Type];
6734 -- We turn off all checks for the conversion of N to the target
6735 -- base type, since we generate the explicit check to ensure that
6736 -- the value is non-negative
6739 Tnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', N
);
6742 Insert_Actions
(N
, New_List
(
6743 Make_Object_Declaration
(Loc
,
6744 Defining_Identifier
=> Tnn
,
6745 Object_Definition
=>
6746 New_Occurrence_Of
(Target_Base_Type
, Loc
),
6747 Constant_Present
=> True,
6749 Make_Unchecked_Type_Conversion
(Loc
,
6751 New_Occurrence_Of
(Target_Base_Type
, Loc
),
6752 Expression
=> Duplicate_Subexpr
(N
))),
6754 Make_Raise_Constraint_Error
(Loc
,
6759 Left_Opnd
=> Duplicate_Subexpr
(N
),
6760 Right_Opnd
=> Make_Integer_Literal
(Loc
, Uint_0
)),
6764 Left_Opnd
=> New_Occurrence_Of
(Tnn
, Loc
),
6766 New_Occurrence_Of
(Target_Type
, Loc
))),
6769 Suppress
=> All_Checks
);
6771 -- Set the Etype explicitly, because Insert_Actions may have
6772 -- placed the declaration in the freeze list for an enclosing
6773 -- construct, and thus it is not analyzed yet.
6775 Set_Etype
(Tnn
, Target_Base_Type
);
6776 Rewrite
(N
, New_Occurrence_Of
(Tnn
, Loc
));
6780 end Generate_Range_Check
;
6786 function Get_Check_Id
(N
: Name_Id
) return Check_Id
is
6788 -- For standard check name, we can do a direct computation
6790 if N
in First_Check_Name
.. Last_Check_Name
then
6791 return Check_Id
(N
- (First_Check_Name
- 1));
6793 -- For non-standard names added by pragma Check_Name, search table
6796 for J
in All_Checks
+ 1 .. Check_Names
.Last
loop
6797 if Check_Names
.Table
(J
) = N
then
6803 -- No matching name found
6808 ---------------------
6809 -- Get_Discriminal --
6810 ---------------------
6812 function Get_Discriminal
(E
: Entity_Id
; Bound
: Node_Id
) return Node_Id
is
6813 Loc
: constant Source_Ptr
:= Sloc
(E
);
6818 -- The bound can be a bona fide parameter of a protected operation,
6819 -- rather than a prival encoded as an in-parameter.
6821 if No
(Discriminal_Link
(Entity
(Bound
))) then
6825 -- Climb the scope stack looking for an enclosing protected type. If
6826 -- we run out of scopes, return the bound itself.
6829 while Present
(Sc
) loop
6830 if Sc
= Standard_Standard
then
6832 elsif Ekind
(Sc
) = E_Protected_Type
then
6839 D
:= First_Discriminant
(Sc
);
6840 while Present
(D
) loop
6841 if Chars
(D
) = Chars
(Bound
) then
6842 return New_Occurrence_Of
(Discriminal
(D
), Loc
);
6845 Next_Discriminant
(D
);
6849 end Get_Discriminal
;
6851 ----------------------
6852 -- Get_Range_Checks --
6853 ----------------------
6855 function Get_Range_Checks
6857 Target_Typ
: Entity_Id
;
6858 Source_Typ
: Entity_Id
:= Empty
;
6859 Warn_Node
: Node_Id
:= Empty
) return Check_Result
6863 Selected_Range_Checks
(Ck_Node
, Target_Typ
, Source_Typ
, Warn_Node
);
6864 end Get_Range_Checks
;
6870 function Guard_Access
6873 Ck_Node
: Node_Id
) return Node_Id
6876 if Nkind
(Cond
) = N_Or_Else
then
6877 Set_Paren_Count
(Cond
, 1);
6880 if Nkind
(Ck_Node
) = N_Allocator
then
6888 Left_Opnd
=> Duplicate_Subexpr_No_Checks
(Ck_Node
),
6889 Right_Opnd
=> Make_Null
(Loc
)),
6890 Right_Opnd
=> Cond
);
6894 -----------------------------
6895 -- Index_Checks_Suppressed --
6896 -----------------------------
6898 function Index_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
6900 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
6901 return Is_Check_Suppressed
(E
, Index_Check
);
6903 return Scope_Suppress
.Suppress
(Index_Check
);
6905 end Index_Checks_Suppressed
;
6911 procedure Initialize
is
6913 for J
in Determine_Range_Cache_N
'Range loop
6914 Determine_Range_Cache_N
(J
) := Empty
;
6919 for J
in Int
range 1 .. All_Checks
loop
6920 Check_Names
.Append
(Name_Id
(Int
(First_Check_Name
) + J
- 1));
6924 -------------------------
6925 -- Insert_Range_Checks --
6926 -------------------------
6928 procedure Insert_Range_Checks
6929 (Checks
: Check_Result
;
6931 Suppress_Typ
: Entity_Id
;
6932 Static_Sloc
: Source_Ptr
:= No_Location
;
6933 Flag_Node
: Node_Id
:= Empty
;
6934 Do_Before
: Boolean := False)
6936 Internal_Flag_Node
: Node_Id
:= Flag_Node
;
6937 Internal_Static_Sloc
: Source_Ptr
:= Static_Sloc
;
6939 Check_Node
: Node_Id
;
6940 Checks_On
: constant Boolean :=
6941 (not Index_Checks_Suppressed
(Suppress_Typ
))
6942 or else (not Range_Checks_Suppressed
(Suppress_Typ
));
6945 -- For now we just return if Checks_On is false, however this should be
6946 -- enhanced to check for an always True value in the condition and to
6947 -- generate a compilation warning???
6949 if not Expander_Active
or not Checks_On
then
6953 if Static_Sloc
= No_Location
then
6954 Internal_Static_Sloc
:= Sloc
(Node
);
6957 if No
(Flag_Node
) then
6958 Internal_Flag_Node
:= Node
;
6961 for J
in 1 .. 2 loop
6962 exit when No
(Checks
(J
));
6964 if Nkind
(Checks
(J
)) = N_Raise_Constraint_Error
6965 and then Present
(Condition
(Checks
(J
)))
6967 if not Has_Dynamic_Range_Check
(Internal_Flag_Node
) then
6968 Check_Node
:= Checks
(J
);
6969 Mark_Rewrite_Insertion
(Check_Node
);
6972 Insert_Before_And_Analyze
(Node
, Check_Node
);
6974 Insert_After_And_Analyze
(Node
, Check_Node
);
6977 Set_Has_Dynamic_Range_Check
(Internal_Flag_Node
);
6982 Make_Raise_Constraint_Error
(Internal_Static_Sloc
,
6983 Reason
=> CE_Range_Check_Failed
);
6984 Mark_Rewrite_Insertion
(Check_Node
);
6987 Insert_Before_And_Analyze
(Node
, Check_Node
);
6989 Insert_After_And_Analyze
(Node
, Check_Node
);
6993 end Insert_Range_Checks
;
6995 ------------------------
6996 -- Insert_Valid_Check --
6997 ------------------------
6999 procedure Insert_Valid_Check
(Expr
: Node_Id
) is
7000 Loc
: constant Source_Ptr
:= Sloc
(Expr
);
7001 Typ
: constant Entity_Id
:= Etype
(Expr
);
7005 -- Do not insert if checks off, or if not checking validity or
7006 -- if expression is known to be valid
7008 if not Validity_Checks_On
7009 or else Range_Or_Validity_Checks_Suppressed
(Expr
)
7010 or else Expr_Known_Valid
(Expr
)
7015 -- Do not insert checks within a predicate function. This will arise
7016 -- if the current unit and the predicate function are being compiled
7017 -- with validity checks enabled.
7019 if Present
(Predicate_Function
(Typ
))
7020 and then Current_Scope
= Predicate_Function
(Typ
)
7025 -- If the expression is a packed component of a modular type of the
7026 -- right size, the data is always valid.
7028 if Nkind
(Expr
) = N_Selected_Component
7029 and then Present
(Component_Clause
(Entity
(Selector_Name
(Expr
))))
7030 and then Is_Modular_Integer_Type
(Typ
)
7031 and then Modulus
(Typ
) = 2 ** Esize
(Entity
(Selector_Name
(Expr
)))
7036 -- If we have a checked conversion, then validity check applies to
7037 -- the expression inside the conversion, not the result, since if
7038 -- the expression inside is valid, then so is the conversion result.
7041 while Nkind
(Exp
) = N_Type_Conversion
loop
7042 Exp
:= Expression
(Exp
);
7045 -- We are about to insert the validity check for Exp. We save and
7046 -- reset the Do_Range_Check flag over this validity check, and then
7047 -- put it back for the final original reference (Exp may be rewritten).
7050 DRC
: constant Boolean := Do_Range_Check
(Exp
);
7055 Set_Do_Range_Check
(Exp
, False);
7057 -- Force evaluation to avoid multiple reads for atomic/volatile
7059 -- Note: we set Name_Req to False. We used to set it to True, with
7060 -- the thinking that a name is required as the prefix of the 'Valid
7061 -- call, but in fact the check that the prefix of an attribute is
7062 -- a name is in the parser, and we just don't require it here.
7063 -- Moreover, when we set Name_Req to True, that interfered with the
7064 -- checking for Volatile, since we couldn't just capture the value.
7066 if Is_Entity_Name
(Exp
)
7067 and then Is_Volatile
(Entity
(Exp
))
7069 -- Same reasoning as above for setting Name_Req to False
7071 Force_Evaluation
(Exp
, Name_Req
=> False);
7074 -- Build the prefix for the 'Valid call
7076 PV
:= Duplicate_Subexpr_No_Checks
(Exp
, Name_Req
=> False);
7078 -- A rather specialized test. If PV is an analyzed expression which
7079 -- is an indexed component of a packed array that has not been
7080 -- properly expanded, turn off its Analyzed flag to make sure it
7081 -- gets properly reexpanded. If the prefix is an access value,
7082 -- the dereference will be added later.
7084 -- The reason this arises is that Duplicate_Subexpr_No_Checks did
7085 -- an analyze with the old parent pointer. This may point e.g. to
7086 -- a subprogram call, which deactivates this expansion.
7089 and then Nkind
(PV
) = N_Indexed_Component
7090 and then Is_Array_Type
(Etype
(Prefix
(PV
)))
7091 and then Present
(Packed_Array_Impl_Type
(Etype
(Prefix
(PV
))))
7093 Set_Analyzed
(PV
, False);
7096 -- Build the raise CE node to check for validity. We build a type
7097 -- qualification for the prefix, since it may not be of the form of
7098 -- a name, and we don't care in this context!
7101 Make_Raise_Constraint_Error
(Loc
,
7105 Make_Attribute_Reference
(Loc
,
7107 Attribute_Name
=> Name_Valid
)),
7108 Reason
=> CE_Invalid_Data
);
7110 -- Insert the validity check. Note that we do this with validity
7111 -- checks turned off, to avoid recursion, we do not want validity
7112 -- checks on the validity checking code itself.
7114 Insert_Action
(Expr
, CE
, Suppress
=> Validity_Check
);
7116 -- If the expression is a reference to an element of a bit-packed
7117 -- array, then it is rewritten as a renaming declaration. If the
7118 -- expression is an actual in a call, it has not been expanded,
7119 -- waiting for the proper point at which to do it. The same happens
7120 -- with renamings, so that we have to force the expansion now. This
7121 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
7124 if Is_Entity_Name
(Exp
)
7125 and then Nkind
(Parent
(Entity
(Exp
))) =
7126 N_Object_Renaming_Declaration
7129 Old_Exp
: constant Node_Id
:= Name
(Parent
(Entity
(Exp
)));
7131 if Nkind
(Old_Exp
) = N_Indexed_Component
7132 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Old_Exp
)))
7134 Expand_Packed_Element_Reference
(Old_Exp
);
7139 -- Put back the Do_Range_Check flag on the resulting (possibly
7140 -- rewritten) expression.
7142 -- Note: it might be thought that a validity check is not required
7143 -- when a range check is present, but that's not the case, because
7144 -- the back end is allowed to assume for the range check that the
7145 -- operand is within its declared range (an assumption that validity
7146 -- checking is all about NOT assuming).
7148 -- Note: no need to worry about Possible_Local_Raise here, it will
7149 -- already have been called if original node has Do_Range_Check set.
7151 Set_Do_Range_Check
(Exp
, DRC
);
7153 end Insert_Valid_Check
;
7155 -------------------------------------
7156 -- Is_Signed_Integer_Arithmetic_Op --
7157 -------------------------------------
7159 function Is_Signed_Integer_Arithmetic_Op
(N
: Node_Id
) return Boolean is
7162 when N_Op_Abs | N_Op_Add | N_Op_Divide | N_Op_Expon |
7163 N_Op_Minus | N_Op_Mod | N_Op_Multiply | N_Op_Plus |
7164 N_Op_Rem | N_Op_Subtract
=>
7165 return Is_Signed_Integer_Type
(Etype
(N
));
7167 when N_If_Expression | N_Case_Expression
=>
7168 return Is_Signed_Integer_Type
(Etype
(N
));
7173 end Is_Signed_Integer_Arithmetic_Op
;
7175 ----------------------------------
7176 -- Install_Null_Excluding_Check --
7177 ----------------------------------
7179 procedure Install_Null_Excluding_Check
(N
: Node_Id
) is
7180 Loc
: constant Source_Ptr
:= Sloc
(Parent
(N
));
7181 Typ
: constant Entity_Id
:= Etype
(N
);
7183 function Safe_To_Capture_In_Parameter_Value
return Boolean;
7184 -- Determines if it is safe to capture Known_Non_Null status for an
7185 -- the entity referenced by node N. The caller ensures that N is indeed
7186 -- an entity name. It is safe to capture the non-null status for an IN
7187 -- parameter when the reference occurs within a declaration that is sure
7188 -- to be executed as part of the declarative region.
7190 procedure Mark_Non_Null
;
7191 -- After installation of check, if the node in question is an entity
7192 -- name, then mark this entity as non-null if possible.
7194 function Safe_To_Capture_In_Parameter_Value
return Boolean is
7195 E
: constant Entity_Id
:= Entity
(N
);
7196 S
: constant Entity_Id
:= Current_Scope
;
7200 if Ekind
(E
) /= E_In_Parameter
then
7204 -- Two initial context checks. We must be inside a subprogram body
7205 -- with declarations and reference must not appear in nested scopes.
7207 if (Ekind
(S
) /= E_Function
and then Ekind
(S
) /= E_Procedure
)
7208 or else Scope
(E
) /= S
7213 S_Par
:= Parent
(Parent
(S
));
7215 if Nkind
(S_Par
) /= N_Subprogram_Body
7216 or else No
(Declarations
(S_Par
))
7226 -- Retrieve the declaration node of N (if any). Note that N
7227 -- may be a part of a complex initialization expression.
7231 while Present
(P
) loop
7233 -- If we have a short circuit form, and we are within the right
7234 -- hand expression, we return false, since the right hand side
7235 -- is not guaranteed to be elaborated.
7237 if Nkind
(P
) in N_Short_Circuit
7238 and then N
= Right_Opnd
(P
)
7243 -- Similarly, if we are in an if expression and not part of the
7244 -- condition, then we return False, since neither the THEN or
7245 -- ELSE dependent expressions will always be elaborated.
7247 if Nkind
(P
) = N_If_Expression
7248 and then N
/= First
(Expressions
(P
))
7253 -- If within a case expression, and not part of the expression,
7254 -- then return False, since a particular dependent expression
7255 -- may not always be elaborated
7257 if Nkind
(P
) = N_Case_Expression
7258 and then N
/= Expression
(P
)
7263 -- While traversing the parent chain, if node N belongs to a
7264 -- statement, then it may never appear in a declarative region.
7266 if Nkind
(P
) in N_Statement_Other_Than_Procedure_Call
7267 or else Nkind
(P
) = N_Procedure_Call_Statement
7272 -- If we are at a declaration, record it and exit
7274 if Nkind
(P
) in N_Declaration
7275 and then Nkind
(P
) not in N_Subprogram_Specification
7288 return List_Containing
(N_Decl
) = Declarations
(S_Par
);
7290 end Safe_To_Capture_In_Parameter_Value
;
7296 procedure Mark_Non_Null
is
7298 -- Only case of interest is if node N is an entity name
7300 if Is_Entity_Name
(N
) then
7302 -- For sure, we want to clear an indication that this is known to
7303 -- be null, since if we get past this check, it definitely is not.
7305 Set_Is_Known_Null
(Entity
(N
), False);
7307 -- We can mark the entity as known to be non-null if either it is
7308 -- safe to capture the value, or in the case of an IN parameter,
7309 -- which is a constant, if the check we just installed is in the
7310 -- declarative region of the subprogram body. In this latter case,
7311 -- a check is decisive for the rest of the body if the expression
7312 -- is sure to be elaborated, since we know we have to elaborate
7313 -- all declarations before executing the body.
7315 -- Couldn't this always be part of Safe_To_Capture_Value ???
7317 if Safe_To_Capture_Value
(N
, Entity
(N
))
7318 or else Safe_To_Capture_In_Parameter_Value
7320 Set_Is_Known_Non_Null
(Entity
(N
));
7325 -- Start of processing for Install_Null_Excluding_Check
7328 pragma Assert
(Is_Access_Type
(Typ
));
7330 -- No check inside a generic, check will be emitted in instance
7332 if Inside_A_Generic
then
7336 -- No check needed if known to be non-null
7338 if Known_Non_Null
(N
) then
7342 -- If known to be null, here is where we generate a compile time check
7344 if Known_Null
(N
) then
7346 -- Avoid generating warning message inside init procs. In SPARK mode
7347 -- we can go ahead and call Apply_Compile_Time_Constraint_Error
7348 -- since it will be turned into an error in any case.
7350 if (not Inside_Init_Proc
or else SPARK_Mode
= On
)
7352 -- Do not emit the warning within a conditional expression,
7353 -- where the expression might not be evaluated, and the warning
7354 -- appear as extraneous noise.
7356 and then not Within_Case_Or_If_Expression
(N
)
7358 Apply_Compile_Time_Constraint_Error
7359 (N
, "null value not allowed here??", CE_Access_Check_Failed
);
7361 -- Remaining cases, where we silently insert the raise
7365 Make_Raise_Constraint_Error
(Loc
,
7366 Reason
=> CE_Access_Check_Failed
));
7373 -- If entity is never assigned, for sure a warning is appropriate
7375 if Is_Entity_Name
(N
) then
7376 Check_Unset_Reference
(N
);
7379 -- No check needed if checks are suppressed on the range. Note that we
7380 -- don't set Is_Known_Non_Null in this case (we could legitimately do
7381 -- so, since the program is erroneous, but we don't like to casually
7382 -- propagate such conclusions from erroneosity).
7384 if Access_Checks_Suppressed
(Typ
) then
7388 -- No check needed for access to concurrent record types generated by
7389 -- the expander. This is not just an optimization (though it does indeed
7390 -- remove junk checks). It also avoids generation of junk warnings.
7392 if Nkind
(N
) in N_Has_Chars
7393 and then Chars
(N
) = Name_uObject
7394 and then Is_Concurrent_Record_Type
7395 (Directly_Designated_Type
(Etype
(N
)))
7400 -- No check needed in interface thunks since the runtime check is
7401 -- already performed at the caller side.
7403 if Is_Thunk
(Current_Scope
) then
7407 -- No check needed for the Get_Current_Excep.all.all idiom generated by
7408 -- the expander within exception handlers, since we know that the value
7409 -- can never be null.
7411 -- Is this really the right way to do this? Normally we generate such
7412 -- code in the expander with checks off, and that's how we suppress this
7413 -- kind of junk check ???
7415 if Nkind
(N
) = N_Function_Call
7416 and then Nkind
(Name
(N
)) = N_Explicit_Dereference
7417 and then Nkind
(Prefix
(Name
(N
))) = N_Identifier
7418 and then Is_RTE
(Entity
(Prefix
(Name
(N
))), RE_Get_Current_Excep
)
7423 -- Otherwise install access check
7426 Make_Raise_Constraint_Error
(Loc
,
7429 Left_Opnd
=> Duplicate_Subexpr_Move_Checks
(N
),
7430 Right_Opnd
=> Make_Null
(Loc
)),
7431 Reason
=> CE_Access_Check_Failed
));
7434 end Install_Null_Excluding_Check
;
7436 --------------------------
7437 -- Install_Static_Check --
7438 --------------------------
7440 procedure Install_Static_Check
(R_Cno
: Node_Id
; Loc
: Source_Ptr
) is
7441 Stat
: constant Boolean := Is_OK_Static_Expression
(R_Cno
);
7442 Typ
: constant Entity_Id
:= Etype
(R_Cno
);
7446 Make_Raise_Constraint_Error
(Loc
,
7447 Reason
=> CE_Range_Check_Failed
));
7448 Set_Analyzed
(R_Cno
);
7449 Set_Etype
(R_Cno
, Typ
);
7450 Set_Raises_Constraint_Error
(R_Cno
);
7451 Set_Is_Static_Expression
(R_Cno
, Stat
);
7453 -- Now deal with possible local raise handling
7455 Possible_Local_Raise
(R_Cno
, Standard_Constraint_Error
);
7456 end Install_Static_Check
;
7458 -------------------------
7459 -- Is_Check_Suppressed --
7460 -------------------------
7462 function Is_Check_Suppressed
(E
: Entity_Id
; C
: Check_Id
) return Boolean is
7463 Ptr
: Suppress_Stack_Entry_Ptr
;
7466 -- First search the local entity suppress stack. We search this from the
7467 -- top of the stack down so that we get the innermost entry that applies
7468 -- to this case if there are nested entries.
7470 Ptr
:= Local_Suppress_Stack_Top
;
7471 while Ptr
/= null loop
7472 if (Ptr
.Entity
= Empty
or else Ptr
.Entity
= E
)
7473 and then (Ptr
.Check
= All_Checks
or else Ptr
.Check
= C
)
7475 return Ptr
.Suppress
;
7481 -- Now search the global entity suppress table for a matching entry.
7482 -- We also search this from the top down so that if there are multiple
7483 -- pragmas for the same entity, the last one applies (not clear what
7484 -- or whether the RM specifies this handling, but it seems reasonable).
7486 Ptr
:= Global_Suppress_Stack_Top
;
7487 while Ptr
/= null loop
7488 if (Ptr
.Entity
= Empty
or else Ptr
.Entity
= E
)
7489 and then (Ptr
.Check
= All_Checks
or else Ptr
.Check
= C
)
7491 return Ptr
.Suppress
;
7497 -- If we did not find a matching entry, then use the normal scope
7498 -- suppress value after all (actually this will be the global setting
7499 -- since it clearly was not overridden at any point). For a predefined
7500 -- check, we test the specific flag. For a user defined check, we check
7501 -- the All_Checks flag. The Overflow flag requires special handling to
7502 -- deal with the General vs Assertion case
7504 if C
= Overflow_Check
then
7505 return Overflow_Checks_Suppressed
(Empty
);
7506 elsif C
in Predefined_Check_Id
then
7507 return Scope_Suppress
.Suppress
(C
);
7509 return Scope_Suppress
.Suppress
(All_Checks
);
7511 end Is_Check_Suppressed
;
7513 ---------------------
7514 -- Kill_All_Checks --
7515 ---------------------
7517 procedure Kill_All_Checks
is
7519 if Debug_Flag_CC
then
7520 w
("Kill_All_Checks");
7523 -- We reset the number of saved checks to zero, and also modify all
7524 -- stack entries for statement ranges to indicate that the number of
7525 -- checks at each level is now zero.
7527 Num_Saved_Checks
:= 0;
7529 -- Note: the Int'Min here avoids any possibility of J being out of
7530 -- range when called from e.g. Conditional_Statements_Begin.
7532 for J
in 1 .. Int
'Min (Saved_Checks_TOS
, Saved_Checks_Stack
'Last) loop
7533 Saved_Checks_Stack
(J
) := 0;
7535 end Kill_All_Checks
;
7541 procedure Kill_Checks
(V
: Entity_Id
) is
7543 if Debug_Flag_CC
then
7544 w
("Kill_Checks for entity", Int
(V
));
7547 for J
in 1 .. Num_Saved_Checks
loop
7548 if Saved_Checks
(J
).Entity
= V
then
7549 if Debug_Flag_CC
then
7550 w
(" Checks killed for saved check ", J
);
7553 Saved_Checks
(J
).Killed
:= True;
7558 ------------------------------
7559 -- Length_Checks_Suppressed --
7560 ------------------------------
7562 function Length_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
7564 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
7565 return Is_Check_Suppressed
(E
, Length_Check
);
7567 return Scope_Suppress
.Suppress
(Length_Check
);
7569 end Length_Checks_Suppressed
;
7571 -----------------------
7572 -- Make_Bignum_Block --
7573 -----------------------
7575 function Make_Bignum_Block
(Loc
: Source_Ptr
) return Node_Id
is
7576 M
: constant Entity_Id
:= Make_Defining_Identifier
(Loc
, Name_uM
);
7579 Make_Block_Statement
(Loc
,
7581 New_List
(Build_SS_Mark_Call
(Loc
, M
)),
7582 Handled_Statement_Sequence
=>
7583 Make_Handled_Sequence_Of_Statements
(Loc
,
7584 Statements
=> New_List
(Build_SS_Release_Call
(Loc
, M
))));
7585 end Make_Bignum_Block
;
7587 ----------------------------------
7588 -- Minimize_Eliminate_Overflows --
7589 ----------------------------------
7591 -- This is a recursive routine that is called at the top of an expression
7592 -- tree to properly process overflow checking for a whole subtree by making
7593 -- recursive calls to process operands. This processing may involve the use
7594 -- of bignum or long long integer arithmetic, which will change the types
7595 -- of operands and results. That's why we can't do this bottom up (since
7596 -- it would interfere with semantic analysis).
7598 -- What happens is that if MINIMIZED/ELIMINATED mode is in effect then
7599 -- the operator expansion routines, as well as the expansion routines for
7600 -- if/case expression, do nothing (for the moment) except call the routine
7601 -- to apply the overflow check (Apply_Arithmetic_Overflow_Check). That
7602 -- routine does nothing for non top-level nodes, so at the point where the
7603 -- call is made for the top level node, the entire expression subtree has
7604 -- not been expanded, or processed for overflow. All that has to happen as
7605 -- a result of the top level call to this routine.
7607 -- As noted above, the overflow processing works by making recursive calls
7608 -- for the operands, and figuring out what to do, based on the processing
7609 -- of these operands (e.g. if a bignum operand appears, the parent op has
7610 -- to be done in bignum mode), and the determined ranges of the operands.
7612 -- After possible rewriting of a constituent subexpression node, a call is
7613 -- made to either reexpand the node (if nothing has changed) or reanalyze
7614 -- the node (if it has been modified by the overflow check processing). The
7615 -- Analyzed_Flag is set to False before the reexpand/reanalyze. To avoid
7616 -- a recursive call into the whole overflow apparatus, an important rule
7617 -- for this call is that the overflow handling mode must be temporarily set
7620 procedure Minimize_Eliminate_Overflows
7624 Top_Level
: Boolean)
7626 Rtyp
: constant Entity_Id
:= Etype
(N
);
7627 pragma Assert
(Is_Signed_Integer_Type
(Rtyp
));
7628 -- Result type, must be a signed integer type
7630 Check_Mode
: constant Overflow_Mode_Type
:= Overflow_Check_Mode
;
7631 pragma Assert
(Check_Mode
in Minimized_Or_Eliminated
);
7633 Loc
: constant Source_Ptr
:= Sloc
(N
);
7636 -- Ranges of values for right operand (operator case)
7639 -- Ranges of values for left operand (operator case)
7641 LLIB
: constant Entity_Id
:= Base_Type
(Standard_Long_Long_Integer
);
7642 -- Operands and results are of this type when we convert
7644 LLLo
: constant Uint
:= Intval
(Type_Low_Bound
(LLIB
));
7645 LLHi
: constant Uint
:= Intval
(Type_High_Bound
(LLIB
));
7646 -- Bounds of Long_Long_Integer
7648 Binary
: constant Boolean := Nkind
(N
) in N_Binary_Op
;
7649 -- Indicates binary operator case
7652 -- Used in call to Determine_Range
7654 Bignum_Operands
: Boolean;
7655 -- Set True if one or more operands is already of type Bignum, meaning
7656 -- that for sure (regardless of Top_Level setting) we are committed to
7657 -- doing the operation in Bignum mode (or in the case of a case or if
7658 -- expression, converting all the dependent expressions to Bignum).
7660 Long_Long_Integer_Operands
: Boolean;
7661 -- Set True if one or more operands is already of type Long_Long_Integer
7662 -- which means that if the result is known to be in the result type
7663 -- range, then we must convert such operands back to the result type.
7665 procedure Reanalyze
(Typ
: Entity_Id
; Suppress
: Boolean := False);
7666 -- This is called when we have modified the node and we therefore need
7667 -- to reanalyze it. It is important that we reset the mode to STRICT for
7668 -- this reanalysis, since if we leave it in MINIMIZED or ELIMINATED mode
7669 -- we would reenter this routine recursively which would not be good.
7670 -- The argument Suppress is set True if we also want to suppress
7671 -- overflow checking for the reexpansion (this is set when we know
7672 -- overflow is not possible). Typ is the type for the reanalysis.
7674 procedure Reexpand
(Suppress
: Boolean := False);
7675 -- This is like Reanalyze, but does not do the Analyze step, it only
7676 -- does a reexpansion. We do this reexpansion in STRICT mode, so that
7677 -- instead of reentering the MINIMIZED/ELIMINATED mode processing, we
7678 -- follow the normal expansion path (e.g. converting A**4 to A**2**2).
7679 -- Note that skipping reanalysis is not just an optimization, testing
7680 -- has showed up several complex cases in which reanalyzing an already
7681 -- analyzed node causes incorrect behavior.
7683 function In_Result_Range
return Boolean;
7684 -- Returns True iff Lo .. Hi are within range of the result type
7686 procedure Max
(A
: in out Uint
; B
: Uint
);
7687 -- If A is No_Uint, sets A to B, else to UI_Max (A, B)
7689 procedure Min
(A
: in out Uint
; B
: Uint
);
7690 -- If A is No_Uint, sets A to B, else to UI_Min (A, B)
7692 ---------------------
7693 -- In_Result_Range --
7694 ---------------------
7696 function In_Result_Range
return Boolean is
7698 if Lo
= No_Uint
or else Hi
= No_Uint
then
7701 elsif Is_OK_Static_Subtype
(Etype
(N
)) then
7702 return Lo
>= Expr_Value
(Type_Low_Bound
(Rtyp
))
7704 Hi
<= Expr_Value
(Type_High_Bound
(Rtyp
));
7707 return Lo
>= Expr_Value
(Type_Low_Bound
(Base_Type
(Rtyp
)))
7709 Hi
<= Expr_Value
(Type_High_Bound
(Base_Type
(Rtyp
)));
7711 end In_Result_Range
;
7717 procedure Max
(A
: in out Uint
; B
: Uint
) is
7719 if A
= No_Uint
or else B
> A
then
7728 procedure Min
(A
: in out Uint
; B
: Uint
) is
7730 if A
= No_Uint
or else B
< A
then
7739 procedure Reanalyze
(Typ
: Entity_Id
; Suppress
: Boolean := False) is
7740 Svg
: constant Overflow_Mode_Type
:=
7741 Scope_Suppress
.Overflow_Mode_General
;
7742 Sva
: constant Overflow_Mode_Type
:=
7743 Scope_Suppress
.Overflow_Mode_Assertions
;
7744 Svo
: constant Boolean :=
7745 Scope_Suppress
.Suppress
(Overflow_Check
);
7748 Scope_Suppress
.Overflow_Mode_General
:= Strict
;
7749 Scope_Suppress
.Overflow_Mode_Assertions
:= Strict
;
7752 Scope_Suppress
.Suppress
(Overflow_Check
) := True;
7755 Analyze_And_Resolve
(N
, Typ
);
7757 Scope_Suppress
.Suppress
(Overflow_Check
) := Svo
;
7758 Scope_Suppress
.Overflow_Mode_General
:= Svg
;
7759 Scope_Suppress
.Overflow_Mode_Assertions
:= Sva
;
7766 procedure Reexpand
(Suppress
: Boolean := False) is
7767 Svg
: constant Overflow_Mode_Type
:=
7768 Scope_Suppress
.Overflow_Mode_General
;
7769 Sva
: constant Overflow_Mode_Type
:=
7770 Scope_Suppress
.Overflow_Mode_Assertions
;
7771 Svo
: constant Boolean :=
7772 Scope_Suppress
.Suppress
(Overflow_Check
);
7775 Scope_Suppress
.Overflow_Mode_General
:= Strict
;
7776 Scope_Suppress
.Overflow_Mode_Assertions
:= Strict
;
7777 Set_Analyzed
(N
, False);
7780 Scope_Suppress
.Suppress
(Overflow_Check
) := True;
7785 Scope_Suppress
.Suppress
(Overflow_Check
) := Svo
;
7786 Scope_Suppress
.Overflow_Mode_General
:= Svg
;
7787 Scope_Suppress
.Overflow_Mode_Assertions
:= Sva
;
7790 -- Start of processing for Minimize_Eliminate_Overflows
7793 -- Case where we do not have a signed integer arithmetic operation
7795 if not Is_Signed_Integer_Arithmetic_Op
(N
) then
7797 -- Use the normal Determine_Range routine to get the range. We
7798 -- don't require operands to be valid, invalid values may result in
7799 -- rubbish results where the result has not been properly checked for
7800 -- overflow, that's fine.
7802 Determine_Range
(N
, OK
, Lo
, Hi
, Assume_Valid
=> False);
7804 -- If Determine_Range did not work (can this in fact happen? Not
7805 -- clear but might as well protect), use type bounds.
7808 Lo
:= Intval
(Type_Low_Bound
(Base_Type
(Etype
(N
))));
7809 Hi
:= Intval
(Type_High_Bound
(Base_Type
(Etype
(N
))));
7812 -- If we don't have a binary operator, all we have to do is to set
7813 -- the Hi/Lo range, so we are done.
7817 -- Processing for if expression
7819 elsif Nkind
(N
) = N_If_Expression
then
7821 Then_DE
: constant Node_Id
:= Next
(First
(Expressions
(N
)));
7822 Else_DE
: constant Node_Id
:= Next
(Then_DE
);
7825 Bignum_Operands
:= False;
7827 Minimize_Eliminate_Overflows
7828 (Then_DE
, Lo
, Hi
, Top_Level
=> False);
7830 if Lo
= No_Uint
then
7831 Bignum_Operands
:= True;
7834 Minimize_Eliminate_Overflows
7835 (Else_DE
, Rlo
, Rhi
, Top_Level
=> False);
7837 if Rlo
= No_Uint
then
7838 Bignum_Operands
:= True;
7840 Long_Long_Integer_Operands
:=
7841 Etype
(Then_DE
) = LLIB
or else Etype
(Else_DE
) = LLIB
;
7847 -- If at least one of our operands is now Bignum, we must rebuild
7848 -- the if expression to use Bignum operands. We will analyze the
7849 -- rebuilt if expression with overflow checks off, since once we
7850 -- are in bignum mode, we are all done with overflow checks.
7852 if Bignum_Operands
then
7854 Make_If_Expression
(Loc
,
7855 Expressions
=> New_List
(
7856 Remove_Head
(Expressions
(N
)),
7857 Convert_To_Bignum
(Then_DE
),
7858 Convert_To_Bignum
(Else_DE
)),
7859 Is_Elsif
=> Is_Elsif
(N
)));
7861 Reanalyze
(RTE
(RE_Bignum
), Suppress
=> True);
7863 -- If we have no Long_Long_Integer operands, then we are in result
7864 -- range, since it means that none of our operands felt the need
7865 -- to worry about overflow (otherwise it would have already been
7866 -- converted to long long integer or bignum). We reexpand to
7867 -- complete the expansion of the if expression (but we do not
7868 -- need to reanalyze).
7870 elsif not Long_Long_Integer_Operands
then
7871 Set_Do_Overflow_Check
(N
, False);
7874 -- Otherwise convert us to long long integer mode. Note that we
7875 -- don't need any further overflow checking at this level.
7878 Convert_To_And_Rewrite
(LLIB
, Then_DE
);
7879 Convert_To_And_Rewrite
(LLIB
, Else_DE
);
7880 Set_Etype
(N
, LLIB
);
7882 -- Now reanalyze with overflow checks off
7884 Set_Do_Overflow_Check
(N
, False);
7885 Reanalyze
(LLIB
, Suppress
=> True);
7891 -- Here for case expression
7893 elsif Nkind
(N
) = N_Case_Expression
then
7894 Bignum_Operands
:= False;
7895 Long_Long_Integer_Operands
:= False;
7901 -- Loop through expressions applying recursive call
7903 Alt
:= First
(Alternatives
(N
));
7904 while Present
(Alt
) loop
7906 Aexp
: constant Node_Id
:= Expression
(Alt
);
7909 Minimize_Eliminate_Overflows
7910 (Aexp
, Lo
, Hi
, Top_Level
=> False);
7912 if Lo
= No_Uint
then
7913 Bignum_Operands
:= True;
7914 elsif Etype
(Aexp
) = LLIB
then
7915 Long_Long_Integer_Operands
:= True;
7922 -- If we have no bignum or long long integer operands, it means
7923 -- that none of our dependent expressions could raise overflow.
7924 -- In this case, we simply return with no changes except for
7925 -- resetting the overflow flag, since we are done with overflow
7926 -- checks for this node. We will reexpand to get the needed
7927 -- expansion for the case expression, but we do not need to
7928 -- reanalyze, since nothing has changed.
7930 if not (Bignum_Operands
or Long_Long_Integer_Operands
) then
7931 Set_Do_Overflow_Check
(N
, False);
7932 Reexpand
(Suppress
=> True);
7934 -- Otherwise we are going to rebuild the case expression using
7935 -- either bignum or long long integer operands throughout.
7944 New_Alts
:= New_List
;
7945 Alt
:= First
(Alternatives
(N
));
7946 while Present
(Alt
) loop
7947 if Bignum_Operands
then
7948 New_Exp
:= Convert_To_Bignum
(Expression
(Alt
));
7949 Rtype
:= RTE
(RE_Bignum
);
7951 New_Exp
:= Convert_To
(LLIB
, Expression
(Alt
));
7955 Append_To
(New_Alts
,
7956 Make_Case_Expression_Alternative
(Sloc
(Alt
),
7958 Discrete_Choices
=> Discrete_Choices
(Alt
),
7959 Expression
=> New_Exp
));
7965 Make_Case_Expression
(Loc
,
7966 Expression
=> Expression
(N
),
7967 Alternatives
=> New_Alts
));
7969 Reanalyze
(Rtype
, Suppress
=> True);
7977 -- If we have an arithmetic operator we make recursive calls on the
7978 -- operands to get the ranges (and to properly process the subtree
7979 -- that lies below us).
7981 Minimize_Eliminate_Overflows
7982 (Right_Opnd
(N
), Rlo
, Rhi
, Top_Level
=> False);
7985 Minimize_Eliminate_Overflows
7986 (Left_Opnd
(N
), Llo
, Lhi
, Top_Level
=> False);
7989 -- Record if we have Long_Long_Integer operands
7991 Long_Long_Integer_Operands
:=
7992 Etype
(Right_Opnd
(N
)) = LLIB
7993 or else (Binary
and then Etype
(Left_Opnd
(N
)) = LLIB
);
7995 -- If either operand is a bignum, then result will be a bignum and we
7996 -- don't need to do any range analysis. As previously discussed we could
7997 -- do range analysis in such cases, but it could mean working with giant
7998 -- numbers at compile time for very little gain (the number of cases
7999 -- in which we could slip back from bignum mode is small).
8001 if Rlo
= No_Uint
or else (Binary
and then Llo
= No_Uint
) then
8004 Bignum_Operands
:= True;
8006 -- Otherwise compute result range
8009 Bignum_Operands
:= False;
8017 Hi
:= UI_Max
(abs Rlo
, abs Rhi
);
8029 -- If the right operand can only be zero, set 0..0
8031 if Rlo
= 0 and then Rhi
= 0 then
8035 -- Possible bounds of division must come from dividing end
8036 -- values of the input ranges (four possibilities), provided
8037 -- zero is not included in the possible values of the right
8040 -- Otherwise, we just consider two intervals of values for
8041 -- the right operand: the interval of negative values (up to
8042 -- -1) and the interval of positive values (starting at 1).
8043 -- Since division by 1 is the identity, and division by -1
8044 -- is negation, we get all possible bounds of division in that
8045 -- case by considering:
8046 -- - all values from the division of end values of input
8048 -- - the end values of the left operand;
8049 -- - the negation of the end values of the left operand.
8053 Mrk
: constant Uintp
.Save_Mark
:= Mark
;
8054 -- Mark so we can release the RR and Ev values
8062 -- Discard extreme values of zero for the divisor, since
8063 -- they will simply result in an exception in any case.
8071 -- Compute possible bounds coming from dividing end
8072 -- values of the input ranges.
8079 Lo
:= UI_Min
(UI_Min
(Ev1
, Ev2
), UI_Min
(Ev3
, Ev4
));
8080 Hi
:= UI_Max
(UI_Max
(Ev1
, Ev2
), UI_Max
(Ev3
, Ev4
));
8082 -- If the right operand can be both negative or positive,
8083 -- include the end values of the left operand in the
8084 -- extreme values, as well as their negation.
8086 if Rlo
< 0 and then Rhi
> 0 then
8093 UI_Min
(UI_Min
(Ev1
, Ev2
), UI_Min
(Ev3
, Ev4
)));
8095 UI_Max
(UI_Max
(Ev1
, Ev2
), UI_Max
(Ev3
, Ev4
)));
8098 -- Release the RR and Ev values
8100 Release_And_Save
(Mrk
, Lo
, Hi
);
8108 -- Discard negative values for the exponent, since they will
8109 -- simply result in an exception in any case.
8117 -- Estimate number of bits in result before we go computing
8118 -- giant useless bounds. Basically the number of bits in the
8119 -- result is the number of bits in the base multiplied by the
8120 -- value of the exponent. If this is big enough that the result
8121 -- definitely won't fit in Long_Long_Integer, switch to bignum
8122 -- mode immediately, and avoid computing giant bounds.
8124 -- The comparison here is approximate, but conservative, it
8125 -- only clicks on cases that are sure to exceed the bounds.
8127 if Num_Bits
(UI_Max
(abs Llo
, abs Lhi
)) * Rhi
+ 1 > 100 then
8131 -- If right operand is zero then result is 1
8138 -- High bound comes either from exponentiation of largest
8139 -- positive value to largest exponent value, or from
8140 -- the exponentiation of most negative value to an
8154 if Rhi
mod 2 = 0 then
8157 Hi2
:= Llo
** (Rhi
- 1);
8163 Hi
:= UI_Max
(Hi1
, Hi2
);
8166 -- Result can only be negative if base can be negative
8169 if Rhi
mod 2 = 0 then
8170 Lo
:= Llo
** (Rhi
- 1);
8175 -- Otherwise low bound is minimum ** minimum
8192 Maxabs
: constant Uint
:= UI_Max
(abs Rlo
, abs Rhi
) - 1;
8193 -- This is the maximum absolute value of the result
8199 -- The result depends only on the sign and magnitude of
8200 -- the right operand, it does not depend on the sign or
8201 -- magnitude of the left operand.
8214 when N_Op_Multiply
=>
8216 -- Possible bounds of multiplication must come from multiplying
8217 -- end values of the input ranges (four possibilities).
8220 Mrk
: constant Uintp
.Save_Mark
:= Mark
;
8221 -- Mark so we can release the Ev values
8223 Ev1
: constant Uint
:= Llo
* Rlo
;
8224 Ev2
: constant Uint
:= Llo
* Rhi
;
8225 Ev3
: constant Uint
:= Lhi
* Rlo
;
8226 Ev4
: constant Uint
:= Lhi
* Rhi
;
8229 Lo
:= UI_Min
(UI_Min
(Ev1
, Ev2
), UI_Min
(Ev3
, Ev4
));
8230 Hi
:= UI_Max
(UI_Max
(Ev1
, Ev2
), UI_Max
(Ev3
, Ev4
));
8232 -- Release the Ev values
8234 Release_And_Save
(Mrk
, Lo
, Hi
);
8237 -- Plus operator (affirmation)
8247 Maxabs
: constant Uint
:= UI_Max
(abs Rlo
, abs Rhi
) - 1;
8248 -- This is the maximum absolute value of the result. Note
8249 -- that the result range does not depend on the sign of the
8256 -- Case of left operand negative, which results in a range
8257 -- of -Maxabs .. 0 for those negative values. If there are
8258 -- no negative values then Lo value of result is always 0.
8264 -- Case of left operand positive
8273 when N_Op_Subtract
=>
8277 -- Nothing else should be possible
8280 raise Program_Error
;
8284 -- Here for the case where we have not rewritten anything (no bignum
8285 -- operands or long long integer operands), and we know the result.
8286 -- If we know we are in the result range, and we do not have Bignum
8287 -- operands or Long_Long_Integer operands, we can just reexpand with
8288 -- overflow checks turned off (since we know we cannot have overflow).
8289 -- As always the reexpansion is required to complete expansion of the
8290 -- operator, but we do not need to reanalyze, and we prevent recursion
8291 -- by suppressing the check.
8293 if not (Bignum_Operands
or Long_Long_Integer_Operands
)
8294 and then In_Result_Range
8296 Set_Do_Overflow_Check
(N
, False);
8297 Reexpand
(Suppress
=> True);
8300 -- Here we know that we are not in the result range, and in the general
8301 -- case we will move into either the Bignum or Long_Long_Integer domain
8302 -- to compute the result. However, there is one exception. If we are
8303 -- at the top level, and we do not have Bignum or Long_Long_Integer
8304 -- operands, we will have to immediately convert the result back to
8305 -- the result type, so there is no point in Bignum/Long_Long_Integer
8309 and then not (Bignum_Operands
or Long_Long_Integer_Operands
)
8311 -- One further refinement. If we are at the top level, but our parent
8312 -- is a type conversion, then go into bignum or long long integer node
8313 -- since the result will be converted to that type directly without
8314 -- going through the result type, and we may avoid an overflow. This
8315 -- is the case for example of Long_Long_Integer (A ** 4), where A is
8316 -- of type Integer, and the result A ** 4 fits in Long_Long_Integer
8317 -- but does not fit in Integer.
8319 and then Nkind
(Parent
(N
)) /= N_Type_Conversion
8321 -- Here keep original types, but we need to complete analysis
8323 -- One subtlety. We can't just go ahead and do an analyze operation
8324 -- here because it will cause recursion into the whole MINIMIZED/
8325 -- ELIMINATED overflow processing which is not what we want. Here
8326 -- we are at the top level, and we need a check against the result
8327 -- mode (i.e. we want to use STRICT mode). So do exactly that.
8328 -- Also, we have not modified the node, so this is a case where
8329 -- we need to reexpand, but not reanalyze.
8334 -- Cases where we do the operation in Bignum mode. This happens either
8335 -- because one of our operands is in Bignum mode already, or because
8336 -- the computed bounds are outside the bounds of Long_Long_Integer,
8337 -- which in some cases can be indicated by Hi and Lo being No_Uint.
8339 -- Note: we could do better here and in some cases switch back from
8340 -- Bignum mode to normal mode, e.g. big mod 2 must be in the range
8341 -- 0 .. 1, but the cases are rare and it is not worth the effort.
8342 -- Failing to do this switching back is only an efficiency issue.
8344 elsif Lo
= No_Uint
or else Lo
< LLLo
or else Hi
> LLHi
then
8346 -- OK, we are definitely outside the range of Long_Long_Integer. The
8347 -- question is whether to move to Bignum mode, or stay in the domain
8348 -- of Long_Long_Integer, signalling that an overflow check is needed.
8350 -- Obviously in MINIMIZED mode we stay with LLI, since we are not in
8351 -- the Bignum business. In ELIMINATED mode, we will normally move
8352 -- into Bignum mode, but there is an exception if neither of our
8353 -- operands is Bignum now, and we are at the top level (Top_Level
8354 -- set True). In this case, there is no point in moving into Bignum
8355 -- mode to prevent overflow if the caller will immediately convert
8356 -- the Bignum value back to LLI with an overflow check. It's more
8357 -- efficient to stay in LLI mode with an overflow check (if needed)
8359 if Check_Mode
= Minimized
8360 or else (Top_Level
and not Bignum_Operands
)
8362 if Do_Overflow_Check
(N
) then
8363 Enable_Overflow_Check
(N
);
8366 -- The result now has to be in Long_Long_Integer mode, so adjust
8367 -- the possible range to reflect this. Note these calls also
8368 -- change No_Uint values from the top level case to LLI bounds.
8373 -- Otherwise we are in ELIMINATED mode and we switch to Bignum mode
8376 pragma Assert
(Check_Mode
= Eliminated
);
8385 Fent
:= RTE
(RE_Big_Abs
);
8388 Fent
:= RTE
(RE_Big_Add
);
8391 Fent
:= RTE
(RE_Big_Div
);
8394 Fent
:= RTE
(RE_Big_Exp
);
8397 Fent
:= RTE
(RE_Big_Neg
);
8400 Fent
:= RTE
(RE_Big_Mod
);
8402 when N_Op_Multiply
=>
8403 Fent
:= RTE
(RE_Big_Mul
);
8406 Fent
:= RTE
(RE_Big_Rem
);
8408 when N_Op_Subtract
=>
8409 Fent
:= RTE
(RE_Big_Sub
);
8411 -- Anything else is an internal error, this includes the
8412 -- N_Op_Plus case, since how can plus cause the result
8413 -- to be out of range if the operand is in range?
8416 raise Program_Error
;
8419 -- Construct argument list for Bignum call, converting our
8420 -- operands to Bignum form if they are not already there.
8425 Append_To
(Args
, Convert_To_Bignum
(Left_Opnd
(N
)));
8428 Append_To
(Args
, Convert_To_Bignum
(Right_Opnd
(N
)));
8430 -- Now rewrite the arithmetic operator with a call to the
8431 -- corresponding bignum function.
8434 Make_Function_Call
(Loc
,
8435 Name
=> New_Occurrence_Of
(Fent
, Loc
),
8436 Parameter_Associations
=> Args
));
8437 Reanalyze
(RTE
(RE_Bignum
), Suppress
=> True);
8439 -- Indicate result is Bignum mode
8447 -- Otherwise we are in range of Long_Long_Integer, so no overflow
8448 -- check is required, at least not yet.
8451 Set_Do_Overflow_Check
(N
, False);
8454 -- Here we are not in Bignum territory, but we may have long long
8455 -- integer operands that need special handling. First a special check:
8456 -- If an exponentiation operator exponent is of type Long_Long_Integer,
8457 -- it means we converted it to prevent overflow, but exponentiation
8458 -- requires a Natural right operand, so convert it back to Natural.
8459 -- This conversion may raise an exception which is fine.
8461 if Nkind
(N
) = N_Op_Expon
and then Etype
(Right_Opnd
(N
)) = LLIB
then
8462 Convert_To_And_Rewrite
(Standard_Natural
, Right_Opnd
(N
));
8465 -- Here we will do the operation in Long_Long_Integer. We do this even
8466 -- if we know an overflow check is required, better to do this in long
8467 -- long integer mode, since we are less likely to overflow.
8469 -- Convert right or only operand to Long_Long_Integer, except that
8470 -- we do not touch the exponentiation right operand.
8472 if Nkind
(N
) /= N_Op_Expon
then
8473 Convert_To_And_Rewrite
(LLIB
, Right_Opnd
(N
));
8476 -- Convert left operand to Long_Long_Integer for binary case
8479 Convert_To_And_Rewrite
(LLIB
, Left_Opnd
(N
));
8482 -- Reset node to unanalyzed
8484 Set_Analyzed
(N
, False);
8485 Set_Etype
(N
, Empty
);
8486 Set_Entity
(N
, Empty
);
8488 -- Now analyze this new node. This reanalysis will complete processing
8489 -- for the node. In particular we will complete the expansion of an
8490 -- exponentiation operator (e.g. changing A ** 2 to A * A), and also
8491 -- we will complete any division checks (since we have not changed the
8492 -- setting of the Do_Division_Check flag).
8494 -- We do this reanalysis in STRICT mode to avoid recursion into the
8495 -- MINIMIZED/ELIMINATED handling, since we are now done with that.
8498 SG
: constant Overflow_Mode_Type
:=
8499 Scope_Suppress
.Overflow_Mode_General
;
8500 SA
: constant Overflow_Mode_Type
:=
8501 Scope_Suppress
.Overflow_Mode_Assertions
;
8504 Scope_Suppress
.Overflow_Mode_General
:= Strict
;
8505 Scope_Suppress
.Overflow_Mode_Assertions
:= Strict
;
8507 if not Do_Overflow_Check
(N
) then
8508 Reanalyze
(LLIB
, Suppress
=> True);
8513 Scope_Suppress
.Overflow_Mode_General
:= SG
;
8514 Scope_Suppress
.Overflow_Mode_Assertions
:= SA
;
8516 end Minimize_Eliminate_Overflows
;
8518 -------------------------
8519 -- Overflow_Check_Mode --
8520 -------------------------
8522 function Overflow_Check_Mode
return Overflow_Mode_Type
is
8524 if In_Assertion_Expr
= 0 then
8525 return Scope_Suppress
.Overflow_Mode_General
;
8527 return Scope_Suppress
.Overflow_Mode_Assertions
;
8529 end Overflow_Check_Mode
;
8531 --------------------------------
8532 -- Overflow_Checks_Suppressed --
8533 --------------------------------
8535 function Overflow_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
8537 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
8538 return Is_Check_Suppressed
(E
, Overflow_Check
);
8540 return Scope_Suppress
.Suppress
(Overflow_Check
);
8542 end Overflow_Checks_Suppressed
;
8544 ---------------------------------
8545 -- Predicate_Checks_Suppressed --
8546 ---------------------------------
8548 function Predicate_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
8550 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
8551 return Is_Check_Suppressed
(E
, Predicate_Check
);
8553 return Scope_Suppress
.Suppress
(Predicate_Check
);
8555 end Predicate_Checks_Suppressed
;
8557 -----------------------------
8558 -- Range_Checks_Suppressed --
8559 -----------------------------
8561 function Range_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
8564 if Kill_Range_Checks
(E
) then
8567 elsif Checks_May_Be_Suppressed
(E
) then
8568 return Is_Check_Suppressed
(E
, Range_Check
);
8572 return Scope_Suppress
.Suppress
(Range_Check
);
8573 end Range_Checks_Suppressed
;
8575 -----------------------------------------
8576 -- Range_Or_Validity_Checks_Suppressed --
8577 -----------------------------------------
8579 -- Note: the coding would be simpler here if we simply made appropriate
8580 -- calls to Range/Validity_Checks_Suppressed, but that would result in
8581 -- duplicated checks which we prefer to avoid.
8583 function Range_Or_Validity_Checks_Suppressed
8584 (Expr
: Node_Id
) return Boolean
8587 -- Immediate return if scope checks suppressed for either check
8589 if Scope_Suppress
.Suppress
(Range_Check
)
8591 Scope_Suppress
.Suppress
(Validity_Check
)
8596 -- If no expression, that's odd, decide that checks are suppressed,
8597 -- since we don't want anyone trying to do checks in this case, which
8598 -- is most likely the result of some other error.
8604 -- Expression is present, so perform suppress checks on type
8607 Typ
: constant Entity_Id
:= Etype
(Expr
);
8609 if Checks_May_Be_Suppressed
(Typ
)
8610 and then (Is_Check_Suppressed
(Typ
, Range_Check
)
8612 Is_Check_Suppressed
(Typ
, Validity_Check
))
8618 -- If expression is an entity name, perform checks on this entity
8620 if Is_Entity_Name
(Expr
) then
8622 Ent
: constant Entity_Id
:= Entity
(Expr
);
8624 if Checks_May_Be_Suppressed
(Ent
) then
8625 return Is_Check_Suppressed
(Ent
, Range_Check
)
8626 or else Is_Check_Suppressed
(Ent
, Validity_Check
);
8631 -- If we fall through, no checks suppressed
8634 end Range_Or_Validity_Checks_Suppressed
;
8640 procedure Remove_Checks
(Expr
: Node_Id
) is
8641 function Process
(N
: Node_Id
) return Traverse_Result
;
8642 -- Process a single node during the traversal
8644 procedure Traverse
is new Traverse_Proc
(Process
);
8645 -- The traversal procedure itself
8651 function Process
(N
: Node_Id
) return Traverse_Result
is
8653 if Nkind
(N
) not in N_Subexpr
then
8657 Set_Do_Range_Check
(N
, False);
8661 Traverse
(Left_Opnd
(N
));
8664 when N_Attribute_Reference
=>
8665 Set_Do_Overflow_Check
(N
, False);
8667 when N_Function_Call
=>
8668 Set_Do_Tag_Check
(N
, False);
8671 Set_Do_Overflow_Check
(N
, False);
8675 Set_Do_Division_Check
(N
, False);
8678 Set_Do_Length_Check
(N
, False);
8681 Set_Do_Division_Check
(N
, False);
8684 Set_Do_Length_Check
(N
, False);
8687 Set_Do_Division_Check
(N
, False);
8690 Set_Do_Length_Check
(N
, False);
8697 Traverse
(Left_Opnd
(N
));
8700 when N_Selected_Component
=>
8701 Set_Do_Discriminant_Check
(N
, False);
8703 when N_Type_Conversion
=>
8704 Set_Do_Length_Check
(N
, False);
8705 Set_Do_Tag_Check
(N
, False);
8706 Set_Do_Overflow_Check
(N
, False);
8715 -- Start of processing for Remove_Checks
8721 ----------------------------
8722 -- Selected_Length_Checks --
8723 ----------------------------
8725 function Selected_Length_Checks
8727 Target_Typ
: Entity_Id
;
8728 Source_Typ
: Entity_Id
;
8729 Warn_Node
: Node_Id
) return Check_Result
8731 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
8734 Expr_Actual
: Node_Id
;
8736 Cond
: Node_Id
:= Empty
;
8737 Do_Access
: Boolean := False;
8738 Wnode
: Node_Id
:= Warn_Node
;
8739 Ret_Result
: Check_Result
:= (Empty
, Empty
);
8740 Num_Checks
: Natural := 0;
8742 procedure Add_Check
(N
: Node_Id
);
8743 -- Adds the action given to Ret_Result if N is non-Empty
8745 function Get_E_Length
(E
: Entity_Id
; Indx
: Nat
) return Node_Id
;
8746 function Get_N_Length
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
8747 -- Comments required ???
8749 function Same_Bounds
(L
: Node_Id
; R
: Node_Id
) return Boolean;
8750 -- True for equal literals and for nodes that denote the same constant
8751 -- entity, even if its value is not a static constant. This includes the
8752 -- case of a discriminal reference within an init proc. Removes some
8753 -- obviously superfluous checks.
8755 function Length_E_Cond
8756 (Exptyp
: Entity_Id
;
8758 Indx
: Nat
) return Node_Id
;
8759 -- Returns expression to compute:
8760 -- Typ'Length /= Exptyp'Length
8762 function Length_N_Cond
8765 Indx
: Nat
) return Node_Id
;
8766 -- Returns expression to compute:
8767 -- Typ'Length /= Expr'Length
8773 procedure Add_Check
(N
: Node_Id
) is
8777 -- For now, ignore attempt to place more than two checks ???
8778 -- This is really worrisome, are we really discarding checks ???
8780 if Num_Checks
= 2 then
8784 pragma Assert
(Num_Checks
<= 1);
8785 Num_Checks
:= Num_Checks
+ 1;
8786 Ret_Result
(Num_Checks
) := N
;
8794 function Get_E_Length
(E
: Entity_Id
; Indx
: Nat
) return Node_Id
is
8795 SE
: constant Entity_Id
:= Scope
(E
);
8797 E1
: Entity_Id
:= E
;
8800 if Ekind
(Scope
(E
)) = E_Record_Type
8801 and then Has_Discriminants
(Scope
(E
))
8803 N
:= Build_Discriminal_Subtype_Of_Component
(E
);
8806 Insert_Action
(Ck_Node
, N
);
8807 E1
:= Defining_Identifier
(N
);
8811 if Ekind
(E1
) = E_String_Literal_Subtype
then
8813 Make_Integer_Literal
(Loc
,
8814 Intval
=> String_Literal_Length
(E1
));
8816 elsif SE
/= Standard_Standard
8817 and then Ekind
(Scope
(SE
)) = E_Protected_Type
8818 and then Has_Discriminants
(Scope
(SE
))
8819 and then Has_Completion
(Scope
(SE
))
8820 and then not Inside_Init_Proc
8822 -- If the type whose length is needed is a private component
8823 -- constrained by a discriminant, we must expand the 'Length
8824 -- attribute into an explicit computation, using the discriminal
8825 -- of the current protected operation. This is because the actual
8826 -- type of the prival is constructed after the protected opera-
8827 -- tion has been fully expanded.
8830 Indx_Type
: Node_Id
;
8833 Do_Expand
: Boolean := False;
8836 Indx_Type
:= First_Index
(E
);
8838 for J
in 1 .. Indx
- 1 loop
8839 Next_Index
(Indx_Type
);
8842 Get_Index_Bounds
(Indx_Type
, Lo
, Hi
);
8844 if Nkind
(Lo
) = N_Identifier
8845 and then Ekind
(Entity
(Lo
)) = E_In_Parameter
8847 Lo
:= Get_Discriminal
(E
, Lo
);
8851 if Nkind
(Hi
) = N_Identifier
8852 and then Ekind
(Entity
(Hi
)) = E_In_Parameter
8854 Hi
:= Get_Discriminal
(E
, Hi
);
8859 if not Is_Entity_Name
(Lo
) then
8860 Lo
:= Duplicate_Subexpr_No_Checks
(Lo
);
8863 if not Is_Entity_Name
(Hi
) then
8864 Lo
:= Duplicate_Subexpr_No_Checks
(Hi
);
8870 Make_Op_Subtract
(Loc
,
8874 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1));
8879 Make_Attribute_Reference
(Loc
,
8880 Attribute_Name
=> Name_Length
,
8882 New_Occurrence_Of
(E1
, Loc
));
8885 Set_Expressions
(N
, New_List
(
8886 Make_Integer_Literal
(Loc
, Indx
)));
8895 Make_Attribute_Reference
(Loc
,
8896 Attribute_Name
=> Name_Length
,
8898 New_Occurrence_Of
(E1
, Loc
));
8901 Set_Expressions
(N
, New_List
(
8902 Make_Integer_Literal
(Loc
, Indx
)));
8913 function Get_N_Length
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
8916 Make_Attribute_Reference
(Loc
,
8917 Attribute_Name
=> Name_Length
,
8919 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
8920 Expressions
=> New_List
(
8921 Make_Integer_Literal
(Loc
, Indx
)));
8928 function Length_E_Cond
8929 (Exptyp
: Entity_Id
;
8931 Indx
: Nat
) return Node_Id
8936 Left_Opnd
=> Get_E_Length
(Typ
, Indx
),
8937 Right_Opnd
=> Get_E_Length
(Exptyp
, Indx
));
8944 function Length_N_Cond
8947 Indx
: Nat
) return Node_Id
8952 Left_Opnd
=> Get_E_Length
(Typ
, Indx
),
8953 Right_Opnd
=> Get_N_Length
(Expr
, Indx
));
8960 function Same_Bounds
(L
: Node_Id
; R
: Node_Id
) return Boolean is
8963 (Nkind
(L
) = N_Integer_Literal
8964 and then Nkind
(R
) = N_Integer_Literal
8965 and then Intval
(L
) = Intval
(R
))
8969 and then Ekind
(Entity
(L
)) = E_Constant
8970 and then ((Is_Entity_Name
(R
)
8971 and then Entity
(L
) = Entity
(R
))
8973 (Nkind
(R
) = N_Type_Conversion
8974 and then Is_Entity_Name
(Expression
(R
))
8975 and then Entity
(L
) = Entity
(Expression
(R
)))))
8979 and then Ekind
(Entity
(R
)) = E_Constant
8980 and then Nkind
(L
) = N_Type_Conversion
8981 and then Is_Entity_Name
(Expression
(L
))
8982 and then Entity
(R
) = Entity
(Expression
(L
)))
8986 and then Is_Entity_Name
(R
)
8987 and then Entity
(L
) = Entity
(R
)
8988 and then Ekind
(Entity
(L
)) = E_In_Parameter
8989 and then Inside_Init_Proc
);
8992 -- Start of processing for Selected_Length_Checks
8995 if not Expander_Active
then
8999 if Target_Typ
= Any_Type
9000 or else Target_Typ
= Any_Composite
9001 or else Raises_Constraint_Error
(Ck_Node
)
9010 T_Typ
:= Target_Typ
;
9012 if No
(Source_Typ
) then
9013 S_Typ
:= Etype
(Ck_Node
);
9015 S_Typ
:= Source_Typ
;
9018 if S_Typ
= Any_Type
or else S_Typ
= Any_Composite
then
9022 if Is_Access_Type
(T_Typ
) and then Is_Access_Type
(S_Typ
) then
9023 S_Typ
:= Designated_Type
(S_Typ
);
9024 T_Typ
:= Designated_Type
(T_Typ
);
9027 -- A simple optimization for the null case
9029 if Known_Null
(Ck_Node
) then
9034 if Is_Array_Type
(T_Typ
) and then Is_Array_Type
(S_Typ
) then
9035 if Is_Constrained
(T_Typ
) then
9037 -- The checking code to be generated will freeze the corresponding
9038 -- array type. However, we must freeze the type now, so that the
9039 -- freeze node does not appear within the generated if expression,
9042 Freeze_Before
(Ck_Node
, T_Typ
);
9044 Expr_Actual
:= Get_Referenced_Object
(Ck_Node
);
9045 Exptyp
:= Get_Actual_Subtype
(Ck_Node
);
9047 if Is_Access_Type
(Exptyp
) then
9048 Exptyp
:= Designated_Type
(Exptyp
);
9051 -- String_Literal case. This needs to be handled specially be-
9052 -- cause no index types are available for string literals. The
9053 -- condition is simply:
9055 -- T_Typ'Length = string-literal-length
9057 if Nkind
(Expr_Actual
) = N_String_Literal
9058 and then Ekind
(Etype
(Expr_Actual
)) = E_String_Literal_Subtype
9062 Left_Opnd
=> Get_E_Length
(T_Typ
, 1),
9064 Make_Integer_Literal
(Loc
,
9066 String_Literal_Length
(Etype
(Expr_Actual
))));
9068 -- General array case. Here we have a usable actual subtype for
9069 -- the expression, and the condition is built from the two types
9072 -- T_Typ'Length /= Exptyp'Length or else
9073 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
9074 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
9077 elsif Is_Constrained
(Exptyp
) then
9079 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
9092 -- At the library level, we need to ensure that the type of
9093 -- the object is elaborated before the check itself is
9094 -- emitted. This is only done if the object is in the
9095 -- current compilation unit, otherwise the type is frozen
9096 -- and elaborated in its unit.
9098 if Is_Itype
(Exptyp
)
9100 Ekind
(Cunit_Entity
(Current_Sem_Unit
)) = E_Package
9102 not In_Package_Body
(Cunit_Entity
(Current_Sem_Unit
))
9103 and then In_Open_Scopes
(Scope
(Exptyp
))
9105 Ref_Node
:= Make_Itype_Reference
(Sloc
(Ck_Node
));
9106 Set_Itype
(Ref_Node
, Exptyp
);
9107 Insert_Action
(Ck_Node
, Ref_Node
);
9110 L_Index
:= First_Index
(T_Typ
);
9111 R_Index
:= First_Index
(Exptyp
);
9113 for Indx
in 1 .. Ndims
loop
9114 if not (Nkind
(L_Index
) = N_Raise_Constraint_Error
9116 Nkind
(R_Index
) = N_Raise_Constraint_Error
)
9118 Get_Index_Bounds
(L_Index
, L_Low
, L_High
);
9119 Get_Index_Bounds
(R_Index
, R_Low
, R_High
);
9121 -- Deal with compile time length check. Note that we
9122 -- skip this in the access case, because the access
9123 -- value may be null, so we cannot know statically.
9126 and then Compile_Time_Known_Value
(L_Low
)
9127 and then Compile_Time_Known_Value
(L_High
)
9128 and then Compile_Time_Known_Value
(R_Low
)
9129 and then Compile_Time_Known_Value
(R_High
)
9131 if Expr_Value
(L_High
) >= Expr_Value
(L_Low
) then
9132 L_Length
:= Expr_Value
(L_High
) -
9133 Expr_Value
(L_Low
) + 1;
9135 L_Length
:= UI_From_Int
(0);
9138 if Expr_Value
(R_High
) >= Expr_Value
(R_Low
) then
9139 R_Length
:= Expr_Value
(R_High
) -
9140 Expr_Value
(R_Low
) + 1;
9142 R_Length
:= UI_From_Int
(0);
9145 if L_Length
> R_Length
then
9147 (Compile_Time_Constraint_Error
9148 (Wnode
, "too few elements for}??", T_Typ
));
9150 elsif L_Length
< R_Length
then
9152 (Compile_Time_Constraint_Error
9153 (Wnode
, "too many elements for}??", T_Typ
));
9156 -- The comparison for an individual index subtype
9157 -- is omitted if the corresponding index subtypes
9158 -- statically match, since the result is known to
9159 -- be true. Note that this test is worth while even
9160 -- though we do static evaluation, because non-static
9161 -- subtypes can statically match.
9164 Subtypes_Statically_Match
9165 (Etype
(L_Index
), Etype
(R_Index
))
9168 (Same_Bounds
(L_Low
, R_Low
)
9169 and then Same_Bounds
(L_High
, R_High
))
9172 (Cond
, Length_E_Cond
(Exptyp
, T_Typ
, Indx
));
9181 -- Handle cases where we do not get a usable actual subtype that
9182 -- is constrained. This happens for example in the function call
9183 -- and explicit dereference cases. In these cases, we have to get
9184 -- the length or range from the expression itself, making sure we
9185 -- do not evaluate it more than once.
9187 -- Here Ck_Node is the original expression, or more properly the
9188 -- result of applying Duplicate_Expr to the original tree, forcing
9189 -- the result to be a name.
9193 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
9196 -- Build the condition for the explicit dereference case
9198 for Indx
in 1 .. Ndims
loop
9200 (Cond
, Length_N_Cond
(Ck_Node
, T_Typ
, Indx
));
9207 -- Construct the test and insert into the tree
9209 if Present
(Cond
) then
9211 Cond
:= Guard_Access
(Cond
, Loc
, Ck_Node
);
9215 (Make_Raise_Constraint_Error
(Loc
,
9217 Reason
=> CE_Length_Check_Failed
));
9221 end Selected_Length_Checks
;
9223 ---------------------------
9224 -- Selected_Range_Checks --
9225 ---------------------------
9227 function Selected_Range_Checks
9229 Target_Typ
: Entity_Id
;
9230 Source_Typ
: Entity_Id
;
9231 Warn_Node
: Node_Id
) return Check_Result
9233 Loc
: constant Source_Ptr
:= Sloc
(Ck_Node
);
9236 Expr_Actual
: Node_Id
;
9238 Cond
: Node_Id
:= Empty
;
9239 Do_Access
: Boolean := False;
9240 Wnode
: Node_Id
:= Warn_Node
;
9241 Ret_Result
: Check_Result
:= (Empty
, Empty
);
9242 Num_Checks
: Integer := 0;
9244 procedure Add_Check
(N
: Node_Id
);
9245 -- Adds the action given to Ret_Result if N is non-Empty
9247 function Discrete_Range_Cond
9249 Typ
: Entity_Id
) return Node_Id
;
9250 -- Returns expression to compute:
9251 -- Low_Bound (Expr) < Typ'First
9253 -- High_Bound (Expr) > Typ'Last
9255 function Discrete_Expr_Cond
9257 Typ
: Entity_Id
) return Node_Id
;
9258 -- Returns expression to compute:
9263 function Get_E_First_Or_Last
9267 Nam
: Name_Id
) return Node_Id
;
9268 -- Returns an attribute reference
9269 -- E'First or E'Last
9270 -- with a source location of Loc.
9272 -- Nam is Name_First or Name_Last, according to which attribute is
9273 -- desired. If Indx is non-zero, it is passed as a literal in the
9274 -- Expressions of the attribute reference (identifying the desired
9275 -- array dimension).
9277 function Get_N_First
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
9278 function Get_N_Last
(N
: Node_Id
; Indx
: Nat
) return Node_Id
;
9279 -- Returns expression to compute:
9280 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
9282 function Range_E_Cond
9283 (Exptyp
: Entity_Id
;
9287 -- Returns expression to compute:
9288 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
9290 function Range_Equal_E_Cond
9291 (Exptyp
: Entity_Id
;
9293 Indx
: Nat
) return Node_Id
;
9294 -- Returns expression to compute:
9295 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
9297 function Range_N_Cond
9300 Indx
: Nat
) return Node_Id
;
9301 -- Return expression to compute:
9302 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
9308 procedure Add_Check
(N
: Node_Id
) is
9312 -- For now, ignore attempt to place more than 2 checks ???
9314 if Num_Checks
= 2 then
9318 pragma Assert
(Num_Checks
<= 1);
9319 Num_Checks
:= Num_Checks
+ 1;
9320 Ret_Result
(Num_Checks
) := N
;
9324 -------------------------
9325 -- Discrete_Expr_Cond --
9326 -------------------------
9328 function Discrete_Expr_Cond
9330 Typ
: Entity_Id
) return Node_Id
9338 Convert_To
(Base_Type
(Typ
),
9339 Duplicate_Subexpr_No_Checks
(Expr
)),
9341 Convert_To
(Base_Type
(Typ
),
9342 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_First
))),
9347 Convert_To
(Base_Type
(Typ
),
9348 Duplicate_Subexpr_No_Checks
(Expr
)),
9352 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_Last
))));
9353 end Discrete_Expr_Cond
;
9355 -------------------------
9356 -- Discrete_Range_Cond --
9357 -------------------------
9359 function Discrete_Range_Cond
9361 Typ
: Entity_Id
) return Node_Id
9363 LB
: Node_Id
:= Low_Bound
(Expr
);
9364 HB
: Node_Id
:= High_Bound
(Expr
);
9366 Left_Opnd
: Node_Id
;
9367 Right_Opnd
: Node_Id
;
9370 if Nkind
(LB
) = N_Identifier
9371 and then Ekind
(Entity
(LB
)) = E_Discriminant
9373 LB
:= New_Occurrence_Of
(Discriminal
(Entity
(LB
)), Loc
);
9380 (Base_Type
(Typ
), Duplicate_Subexpr_No_Checks
(LB
)),
9385 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_First
)));
9387 if Nkind
(HB
) = N_Identifier
9388 and then Ekind
(Entity
(HB
)) = E_Discriminant
9390 HB
:= New_Occurrence_Of
(Discriminal
(Entity
(HB
)), Loc
);
9397 (Base_Type
(Typ
), Duplicate_Subexpr_No_Checks
(HB
)),
9402 Get_E_First_Or_Last
(Loc
, Typ
, 0, Name_Last
)));
9404 return Make_Or_Else
(Loc
, Left_Opnd
, Right_Opnd
);
9405 end Discrete_Range_Cond
;
9407 -------------------------
9408 -- Get_E_First_Or_Last --
9409 -------------------------
9411 function Get_E_First_Or_Last
9415 Nam
: Name_Id
) return Node_Id
9420 Exprs
:= New_List
(Make_Integer_Literal
(Loc
, UI_From_Int
(Indx
)));
9425 return Make_Attribute_Reference
(Loc
,
9426 Prefix
=> New_Occurrence_Of
(E
, Loc
),
9427 Attribute_Name
=> Nam
,
9428 Expressions
=> Exprs
);
9429 end Get_E_First_Or_Last
;
9435 function Get_N_First
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
9438 Make_Attribute_Reference
(Loc
,
9439 Attribute_Name
=> Name_First
,
9441 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
9442 Expressions
=> New_List
(
9443 Make_Integer_Literal
(Loc
, Indx
)));
9450 function Get_N_Last
(N
: Node_Id
; Indx
: Nat
) return Node_Id
is
9453 Make_Attribute_Reference
(Loc
,
9454 Attribute_Name
=> Name_Last
,
9456 Duplicate_Subexpr_No_Checks
(N
, Name_Req
=> True),
9457 Expressions
=> New_List
(
9458 Make_Integer_Literal
(Loc
, Indx
)));
9465 function Range_E_Cond
9466 (Exptyp
: Entity_Id
;
9468 Indx
: Nat
) return Node_Id
9476 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_First
),
9478 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
9483 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_Last
),
9485 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
9488 ------------------------
9489 -- Range_Equal_E_Cond --
9490 ------------------------
9492 function Range_Equal_E_Cond
9493 (Exptyp
: Entity_Id
;
9495 Indx
: Nat
) return Node_Id
9503 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_First
),
9505 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
9510 Get_E_First_Or_Last
(Loc
, Exptyp
, Indx
, Name_Last
),
9512 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
9513 end Range_Equal_E_Cond
;
9519 function Range_N_Cond
9522 Indx
: Nat
) return Node_Id
9530 Get_N_First
(Expr
, Indx
),
9532 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_First
)),
9537 Get_N_Last
(Expr
, Indx
),
9539 Get_E_First_Or_Last
(Loc
, Typ
, Indx
, Name_Last
)));
9542 -- Start of processing for Selected_Range_Checks
9545 if not Expander_Active
then
9549 if Target_Typ
= Any_Type
9550 or else Target_Typ
= Any_Composite
9551 or else Raises_Constraint_Error
(Ck_Node
)
9560 T_Typ
:= Target_Typ
;
9562 if No
(Source_Typ
) then
9563 S_Typ
:= Etype
(Ck_Node
);
9565 S_Typ
:= Source_Typ
;
9568 if S_Typ
= Any_Type
or else S_Typ
= Any_Composite
then
9572 -- The order of evaluating T_Typ before S_Typ seems to be critical
9573 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
9574 -- in, and since Node can be an N_Range node, it might be invalid.
9575 -- Should there be an assert check somewhere for taking the Etype of
9576 -- an N_Range node ???
9578 if Is_Access_Type
(T_Typ
) and then Is_Access_Type
(S_Typ
) then
9579 S_Typ
:= Designated_Type
(S_Typ
);
9580 T_Typ
:= Designated_Type
(T_Typ
);
9583 -- A simple optimization for the null case
9585 if Known_Null
(Ck_Node
) then
9590 -- For an N_Range Node, check for a null range and then if not
9591 -- null generate a range check action.
9593 if Nkind
(Ck_Node
) = N_Range
then
9595 -- There's no point in checking a range against itself
9597 if Ck_Node
= Scalar_Range
(T_Typ
) then
9602 T_LB
: constant Node_Id
:= Type_Low_Bound
(T_Typ
);
9603 T_HB
: constant Node_Id
:= Type_High_Bound
(T_Typ
);
9604 Known_T_LB
: constant Boolean := Compile_Time_Known_Value
(T_LB
);
9605 Known_T_HB
: constant Boolean := Compile_Time_Known_Value
(T_HB
);
9607 LB
: Node_Id
:= Low_Bound
(Ck_Node
);
9608 HB
: Node_Id
:= High_Bound
(Ck_Node
);
9612 Null_Range
: Boolean;
9613 Out_Of_Range_L
: Boolean;
9614 Out_Of_Range_H
: Boolean;
9617 -- Compute what is known at compile time
9619 if Known_T_LB
and Known_T_HB
then
9620 if Compile_Time_Known_Value
(LB
) then
9623 -- There's no point in checking that a bound is within its
9624 -- own range so pretend that it is known in this case. First
9625 -- deal with low bound.
9627 elsif Ekind
(Etype
(LB
)) = E_Signed_Integer_Subtype
9628 and then Scalar_Range
(Etype
(LB
)) = Scalar_Range
(T_Typ
)
9637 -- Likewise for the high bound
9639 if Compile_Time_Known_Value
(HB
) then
9642 elsif Ekind
(Etype
(HB
)) = E_Signed_Integer_Subtype
9643 and then Scalar_Range
(Etype
(HB
)) = Scalar_Range
(T_Typ
)
9652 -- Check for case where everything is static and we can do the
9653 -- check at compile time. This is skipped if we have an access
9654 -- type, since the access value may be null.
9656 -- ??? This code can be improved since you only need to know that
9657 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
9658 -- compile time to emit pertinent messages.
9660 if Known_T_LB
and Known_T_HB
and Known_LB
and Known_HB
9663 -- Floating-point case
9665 if Is_Floating_Point_Type
(S_Typ
) then
9666 Null_Range
:= Expr_Value_R
(HB
) < Expr_Value_R
(LB
);
9668 (Expr_Value_R
(LB
) < Expr_Value_R
(T_LB
))
9670 (Expr_Value_R
(LB
) > Expr_Value_R
(T_HB
));
9673 (Expr_Value_R
(HB
) > Expr_Value_R
(T_HB
))
9675 (Expr_Value_R
(HB
) < Expr_Value_R
(T_LB
));
9677 -- Fixed or discrete type case
9680 Null_Range
:= Expr_Value
(HB
) < Expr_Value
(LB
);
9682 (Expr_Value
(LB
) < Expr_Value
(T_LB
))
9684 (Expr_Value
(LB
) > Expr_Value
(T_HB
));
9687 (Expr_Value
(HB
) > Expr_Value
(T_HB
))
9689 (Expr_Value
(HB
) < Expr_Value
(T_LB
));
9692 if not Null_Range
then
9693 if Out_Of_Range_L
then
9694 if No
(Warn_Node
) then
9696 (Compile_Time_Constraint_Error
9697 (Low_Bound
(Ck_Node
),
9698 "static value out of range of}??", T_Typ
));
9702 (Compile_Time_Constraint_Error
9704 "static range out of bounds of}??", T_Typ
));
9708 if Out_Of_Range_H
then
9709 if No
(Warn_Node
) then
9711 (Compile_Time_Constraint_Error
9712 (High_Bound
(Ck_Node
),
9713 "static value out of range of}??", T_Typ
));
9717 (Compile_Time_Constraint_Error
9719 "static range out of bounds of}??", T_Typ
));
9726 LB
: Node_Id
:= Low_Bound
(Ck_Node
);
9727 HB
: Node_Id
:= High_Bound
(Ck_Node
);
9730 -- If either bound is a discriminant and we are within the
9731 -- record declaration, it is a use of the discriminant in a
9732 -- constraint of a component, and nothing can be checked
9733 -- here. The check will be emitted within the init proc.
9734 -- Before then, the discriminal has no real meaning.
9735 -- Similarly, if the entity is a discriminal, there is no
9736 -- check to perform yet.
9738 -- The same holds within a discriminated synchronized type,
9739 -- where the discriminant may constrain a component or an
9742 if Nkind
(LB
) = N_Identifier
9743 and then Denotes_Discriminant
(LB
, True)
9745 if Current_Scope
= Scope
(Entity
(LB
))
9746 or else Is_Concurrent_Type
(Current_Scope
)
9747 or else Ekind
(Entity
(LB
)) /= E_Discriminant
9752 New_Occurrence_Of
(Discriminal
(Entity
(LB
)), Loc
);
9756 if Nkind
(HB
) = N_Identifier
9757 and then Denotes_Discriminant
(HB
, True)
9759 if Current_Scope
= Scope
(Entity
(HB
))
9760 or else Is_Concurrent_Type
(Current_Scope
)
9761 or else Ekind
(Entity
(HB
)) /= E_Discriminant
9766 New_Occurrence_Of
(Discriminal
(Entity
(HB
)), Loc
);
9770 Cond
:= Discrete_Range_Cond
(Ck_Node
, T_Typ
);
9771 Set_Paren_Count
(Cond
, 1);
9778 Convert_To
(Base_Type
(Etype
(HB
)),
9779 Duplicate_Subexpr_No_Checks
(HB
)),
9781 Convert_To
(Base_Type
(Etype
(LB
)),
9782 Duplicate_Subexpr_No_Checks
(LB
))),
9783 Right_Opnd
=> Cond
);
9788 elsif Is_Scalar_Type
(S_Typ
) then
9790 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
9791 -- except the above simply sets a flag in the node and lets
9792 -- gigi generate the check base on the Etype of the expression.
9793 -- Sometimes, however we want to do a dynamic check against an
9794 -- arbitrary target type, so we do that here.
9796 if Ekind
(Base_Type
(S_Typ
)) /= Ekind
(Base_Type
(T_Typ
)) then
9797 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
9799 -- For literals, we can tell if the constraint error will be
9800 -- raised at compile time, so we never need a dynamic check, but
9801 -- if the exception will be raised, then post the usual warning,
9802 -- and replace the literal with a raise constraint error
9803 -- expression. As usual, skip this for access types
9805 elsif Compile_Time_Known_Value
(Ck_Node
) and then not Do_Access
then
9807 LB
: constant Node_Id
:= Type_Low_Bound
(T_Typ
);
9808 UB
: constant Node_Id
:= Type_High_Bound
(T_Typ
);
9810 Out_Of_Range
: Boolean;
9811 Static_Bounds
: constant Boolean :=
9812 Compile_Time_Known_Value
(LB
)
9813 and Compile_Time_Known_Value
(UB
);
9816 -- Following range tests should use Sem_Eval routine ???
9818 if Static_Bounds
then
9819 if Is_Floating_Point_Type
(S_Typ
) then
9821 (Expr_Value_R
(Ck_Node
) < Expr_Value_R
(LB
))
9823 (Expr_Value_R
(Ck_Node
) > Expr_Value_R
(UB
));
9825 -- Fixed or discrete type
9829 Expr_Value
(Ck_Node
) < Expr_Value
(LB
)
9831 Expr_Value
(Ck_Node
) > Expr_Value
(UB
);
9834 -- Bounds of the type are static and the literal is out of
9835 -- range so output a warning message.
9837 if Out_Of_Range
then
9838 if No
(Warn_Node
) then
9840 (Compile_Time_Constraint_Error
9842 "static value out of range of}??", T_Typ
));
9846 (Compile_Time_Constraint_Error
9848 "static value out of range of}??", T_Typ
));
9853 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
9857 -- Here for the case of a non-static expression, we need a runtime
9858 -- check unless the source type range is guaranteed to be in the
9859 -- range of the target type.
9862 if not In_Subrange_Of
(S_Typ
, T_Typ
) then
9863 Cond
:= Discrete_Expr_Cond
(Ck_Node
, T_Typ
);
9868 if Is_Array_Type
(T_Typ
) and then Is_Array_Type
(S_Typ
) then
9869 if Is_Constrained
(T_Typ
) then
9871 Expr_Actual
:= Get_Referenced_Object
(Ck_Node
);
9872 Exptyp
:= Get_Actual_Subtype
(Expr_Actual
);
9874 if Is_Access_Type
(Exptyp
) then
9875 Exptyp
:= Designated_Type
(Exptyp
);
9878 -- String_Literal case. This needs to be handled specially be-
9879 -- cause no index types are available for string literals. The
9880 -- condition is simply:
9882 -- T_Typ'Length = string-literal-length
9884 if Nkind
(Expr_Actual
) = N_String_Literal
then
9887 -- General array case. Here we have a usable actual subtype for
9888 -- the expression, and the condition is built from the two types
9890 -- T_Typ'First < Exptyp'First or else
9891 -- T_Typ'Last > Exptyp'Last or else
9892 -- T_Typ'First(1) < Exptyp'First(1) or else
9893 -- T_Typ'Last(1) > Exptyp'Last(1) or else
9896 elsif Is_Constrained
(Exptyp
) then
9898 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
9904 L_Index
:= First_Index
(T_Typ
);
9905 R_Index
:= First_Index
(Exptyp
);
9907 for Indx
in 1 .. Ndims
loop
9908 if not (Nkind
(L_Index
) = N_Raise_Constraint_Error
9910 Nkind
(R_Index
) = N_Raise_Constraint_Error
)
9912 -- Deal with compile time length check. Note that we
9913 -- skip this in the access case, because the access
9914 -- value may be null, so we cannot know statically.
9917 Subtypes_Statically_Match
9918 (Etype
(L_Index
), Etype
(R_Index
))
9920 -- If the target type is constrained then we
9921 -- have to check for exact equality of bounds
9922 -- (required for qualified expressions).
9924 if Is_Constrained
(T_Typ
) then
9927 Range_Equal_E_Cond
(Exptyp
, T_Typ
, Indx
));
9930 (Cond
, Range_E_Cond
(Exptyp
, T_Typ
, Indx
));
9940 -- Handle cases where we do not get a usable actual subtype that
9941 -- is constrained. This happens for example in the function call
9942 -- and explicit dereference cases. In these cases, we have to get
9943 -- the length or range from the expression itself, making sure we
9944 -- do not evaluate it more than once.
9946 -- Here Ck_Node is the original expression, or more properly the
9947 -- result of applying Duplicate_Expr to the original tree,
9948 -- forcing the result to be a name.
9952 Ndims
: constant Nat
:= Number_Dimensions
(T_Typ
);
9955 -- Build the condition for the explicit dereference case
9957 for Indx
in 1 .. Ndims
loop
9959 (Cond
, Range_N_Cond
(Ck_Node
, T_Typ
, Indx
));
9965 -- For a conversion to an unconstrained array type, generate an
9966 -- Action to check that the bounds of the source value are within
9967 -- the constraints imposed by the target type (RM 4.6(38)). No
9968 -- check is needed for a conversion to an access to unconstrained
9969 -- array type, as 4.6(24.15/2) requires the designated subtypes
9970 -- of the two access types to statically match.
9972 if Nkind
(Parent
(Ck_Node
)) = N_Type_Conversion
9973 and then not Do_Access
9976 Opnd_Index
: Node_Id
;
9977 Targ_Index
: Node_Id
;
9978 Opnd_Range
: Node_Id
;
9981 Opnd_Index
:= First_Index
(Get_Actual_Subtype
(Ck_Node
));
9982 Targ_Index
:= First_Index
(T_Typ
);
9983 while Present
(Opnd_Index
) loop
9985 -- If the index is a range, use its bounds. If it is an
9986 -- entity (as will be the case if it is a named subtype
9987 -- or an itype created for a slice) retrieve its range.
9989 if Is_Entity_Name
(Opnd_Index
)
9990 and then Is_Type
(Entity
(Opnd_Index
))
9992 Opnd_Range
:= Scalar_Range
(Entity
(Opnd_Index
));
9994 Opnd_Range
:= Opnd_Index
;
9997 if Nkind
(Opnd_Range
) = N_Range
then
9999 (Low_Bound
(Opnd_Range
), Etype
(Targ_Index
),
10000 Assume_Valid
=> True)
10003 (High_Bound
(Opnd_Range
), Etype
(Targ_Index
),
10004 Assume_Valid
=> True)
10008 -- If null range, no check needed
10011 Compile_Time_Known_Value
(High_Bound
(Opnd_Range
))
10013 Compile_Time_Known_Value
(Low_Bound
(Opnd_Range
))
10015 Expr_Value
(High_Bound
(Opnd_Range
)) <
10016 Expr_Value
(Low_Bound
(Opnd_Range
))
10020 elsif Is_Out_Of_Range
10021 (Low_Bound
(Opnd_Range
), Etype
(Targ_Index
),
10022 Assume_Valid
=> True)
10025 (High_Bound
(Opnd_Range
), Etype
(Targ_Index
),
10026 Assume_Valid
=> True)
10029 (Compile_Time_Constraint_Error
10030 (Wnode
, "value out of range of}??", T_Typ
));
10035 Discrete_Range_Cond
10036 (Opnd_Range
, Etype
(Targ_Index
)));
10040 Next_Index
(Opnd_Index
);
10041 Next_Index
(Targ_Index
);
10048 -- Construct the test and insert into the tree
10050 if Present
(Cond
) then
10052 Cond
:= Guard_Access
(Cond
, Loc
, Ck_Node
);
10056 (Make_Raise_Constraint_Error
(Loc
,
10058 Reason
=> CE_Range_Check_Failed
));
10062 end Selected_Range_Checks
;
10064 -------------------------------
10065 -- Storage_Checks_Suppressed --
10066 -------------------------------
10068 function Storage_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
10070 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
10071 return Is_Check_Suppressed
(E
, Storage_Check
);
10073 return Scope_Suppress
.Suppress
(Storage_Check
);
10075 end Storage_Checks_Suppressed
;
10077 ---------------------------
10078 -- Tag_Checks_Suppressed --
10079 ---------------------------
10081 function Tag_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
10084 and then Checks_May_Be_Suppressed
(E
)
10086 return Is_Check_Suppressed
(E
, Tag_Check
);
10088 return Scope_Suppress
.Suppress
(Tag_Check
);
10090 end Tag_Checks_Suppressed
;
10092 ---------------------------------------
10093 -- Validate_Alignment_Check_Warnings --
10094 ---------------------------------------
10096 procedure Validate_Alignment_Check_Warnings
is
10098 for J
in Alignment_Warnings
.First
.. Alignment_Warnings
.Last
loop
10100 AWR
: Alignment_Warnings_Record
10101 renames Alignment_Warnings
.Table
(J
);
10103 if Known_Alignment
(AWR
.E
)
10104 and then AWR
.A
mod Alignment
(AWR
.E
) = 0
10106 Delete_Warning_And_Continuations
(AWR
.W
);
10110 end Validate_Alignment_Check_Warnings
;
10112 --------------------------
10113 -- Validity_Check_Range --
10114 --------------------------
10116 procedure Validity_Check_Range
(N
: Node_Id
) is
10118 if Validity_Checks_On
and Validity_Check_Operands
then
10119 if Nkind
(N
) = N_Range
then
10120 Ensure_Valid
(Low_Bound
(N
));
10121 Ensure_Valid
(High_Bound
(N
));
10124 end Validity_Check_Range
;
10126 --------------------------------
10127 -- Validity_Checks_Suppressed --
10128 --------------------------------
10130 function Validity_Checks_Suppressed
(E
: Entity_Id
) return Boolean is
10132 if Present
(E
) and then Checks_May_Be_Suppressed
(E
) then
10133 return Is_Check_Suppressed
(E
, Validity_Check
);
10135 return Scope_Suppress
.Suppress
(Validity_Check
);
10137 end Validity_Checks_Suppressed
;