1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2023, 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 Aspects
; use Aspects
;
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Debug
; use Debug
;
30 with Einfo
; use Einfo
;
31 with Einfo
.Entities
; use Einfo
.Entities
;
32 with Einfo
.Utils
; use Einfo
.Utils
;
33 with Elists
; use Elists
;
34 with Errout
; use Errout
;
35 with Eval_Fat
; use Eval_Fat
;
36 with Exp_Util
; use Exp_Util
;
37 with Freeze
; use Freeze
;
39 with Namet
; use Namet
;
40 with Nmake
; use Nmake
;
41 with Nlists
; use Nlists
;
43 with Par_SCO
; use Par_SCO
;
44 with Rtsfind
; use Rtsfind
;
46 with Sem_Aggr
; use Sem_Aggr
;
47 with Sem_Aux
; use Sem_Aux
;
48 with Sem_Cat
; use Sem_Cat
;
49 with Sem_Ch3
; use Sem_Ch3
;
50 with Sem_Ch6
; use Sem_Ch6
;
51 with Sem_Ch8
; use Sem_Ch8
;
52 with Sem_Elab
; use Sem_Elab
;
53 with Sem_Res
; use Sem_Res
;
54 with Sem_Util
; use Sem_Util
;
55 with Sem_Type
; use Sem_Type
;
56 with Sem_Warn
; use Sem_Warn
;
57 with Sinfo
; use Sinfo
;
58 with Sinfo
.Nodes
; use Sinfo
.Nodes
;
59 with Sinfo
.Utils
; use Sinfo
.Utils
;
60 with Snames
; use Snames
;
61 with Stand
; use Stand
;
62 with Stringt
; use Stringt
;
63 with Tbuild
; use Tbuild
;
64 with Warnsw
; use Warnsw
;
66 package body Sem_Eval
is
68 -----------------------------------------
69 -- Handling of Compile Time Evaluation --
70 -----------------------------------------
72 -- The compile time evaluation of expressions is distributed over several
73 -- Eval_xxx procedures. These procedures are called immediately after
74 -- a subexpression is resolved and is therefore accomplished in a bottom
75 -- up fashion. The flags are synthesized using the following approach.
77 -- Is_Static_Expression is determined by following the rules in
78 -- RM-4.9. This involves testing the Is_Static_Expression flag of
79 -- the operands in many cases.
81 -- Raises_Constraint_Error is usually set if any of the operands have
82 -- the flag set or if an attempt to compute the value of the current
83 -- expression results in Constraint_Error.
85 -- The general approach is as follows. First compute Is_Static_Expression.
86 -- If the node is not static, then the flag is left off in the node and
87 -- we are all done. Otherwise for a static node, we test if any of the
88 -- operands will raise Constraint_Error, and if so, propagate the flag
89 -- Raises_Constraint_Error to the result node and we are done (since the
90 -- error was already posted at a lower level).
92 -- For the case of a static node whose operands do not raise constraint
93 -- error, we attempt to evaluate the node. If this evaluation succeeds,
94 -- then the node is replaced by the result of this computation. If the
95 -- evaluation raises Constraint_Error, then we rewrite the node with
96 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
97 -- to post appropriate error messages.
103 type Bits
is array (Nat
range <>) of Boolean;
104 -- Used to convert unsigned (modular) values for folding logical ops
106 -- The following declarations are used to maintain a cache of nodes that
107 -- have compile-time-known values. The cache is maintained only for
108 -- discrete types (the most common case), and is populated by calls to
109 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
110 -- since it is possible for the status to change (in particular it is
111 -- possible for a node to get replaced by a Constraint_Error node).
113 CV_Bits
: constant := 5;
114 -- Number of low order bits of Node_Id value used to reference entries
115 -- in the cache table.
117 CV_Cache_Size
: constant Nat
:= 2 ** CV_Bits
;
118 -- Size of cache for compile time values
120 subtype CV_Range
is Nat
range 0 .. CV_Cache_Size
;
122 type CV_Entry
is record
124 -- We use 'Base here, in case we want to add a predicate to Node_Id
128 type Match_Result
is (Match
, No_Match
, Non_Static
);
129 -- Result returned from functions that test for a matching result. If the
130 -- operands are not OK_Static then Non_Static will be returned. Otherwise
131 -- Match/No_Match is returned depending on whether the match succeeds.
133 type CV_Cache_Array
is array (CV_Range
) of CV_Entry
;
135 CV_Cache
: CV_Cache_Array
;
136 -- This is the actual cache, with entries consisting of node/value pairs,
137 -- and the impossible value Node_High_Bound used for unset entries.
139 type Range_Membership
is (In_Range
, Out_Of_Range
, Unknown
);
140 -- Range membership may either be statically known to be in range or out
141 -- of range, or not statically known. Used for Test_In_Range below.
143 Checking_For_Potentially_Static_Expression
: Boolean := False;
144 -- Global flag that is set True during Analyze_Static_Expression_Function
145 -- in order to verify that the result expression of a static expression
146 -- function is a potentially static function (see RM2022 6.8(5.3)).
148 -----------------------
149 -- Local Subprograms --
150 -----------------------
152 procedure Check_Non_Static_Context_For_Overflow
156 -- For a signed integer type, check non-static overflow in Result when
157 -- Stat is False. This applies also inside inlined code, where the static
158 -- property may be an effect of the inlining, which should not be allowed
159 -- to remove run-time checks (whether during compilation, or even more
160 -- crucially in the special inlining-for-proof in GNATprove mode).
162 function Choice_Matches
164 Choice
: Node_Id
) return Match_Result
;
165 -- Determines whether given value Expr matches the given Choice. The Expr
166 -- can be of discrete, real, or string type and must be a compile time
167 -- known value (it is an error to make the call if these conditions are
168 -- not met). The choice can be a range, subtype name, subtype indication,
169 -- or expression. The returned result is Non_Static if Choice is not
170 -- OK_Static, otherwise either Match or No_Match is returned depending
171 -- on whether Choice matches Expr. This is used for case expression
172 -- alternatives, and also for membership tests. In each case, more
173 -- possibilities are tested than the syntax allows (e.g. membership allows
174 -- subtype indications and non-discrete types, and case allows an OTHERS
175 -- choice), but it does not matter, since we have already done a full
176 -- semantic and syntax check of the construct, so the extra possibilities
177 -- just will not arise for correct expressions.
179 -- Note: if Choice_Matches finds that a choice raises Constraint_Error, e.g
180 -- a reference to a type, one of whose bounds raises Constraint_Error, then
181 -- it also sets the Raises_Constraint_Error flag on the Choice itself.
183 function Choices_Match
185 Choices
: List_Id
) return Match_Result
;
186 -- This function applies Choice_Matches to each element of Choices. If the
187 -- result is No_Match, then it continues and checks the next element. If
188 -- the result is Match or Non_Static, this result is immediately given
189 -- as the result without checking the rest of the list. Expr can be of
190 -- discrete, real, or string type and must be a compile-time-known value
191 -- (it is an error to make the call if these conditions are not met).
193 procedure Eval_Intrinsic_Call
(N
: Node_Id
; E
: Entity_Id
);
194 -- Evaluate a call N to an intrinsic subprogram E.
196 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
;
197 -- Check whether an arithmetic operation with universal operands which is a
198 -- rewritten function call with an explicit scope indication is ambiguous:
199 -- P."+" (1, 2) will be ambiguous if there is more than one visible numeric
200 -- type declared in P and the context does not impose a type on the result
201 -- (e.g. in the expression of a type conversion). If ambiguous, emit an
202 -- error and return Empty, else return the result type of the operator.
204 procedure Fold_Dummy
(N
: Node_Id
; Typ
: Entity_Id
);
205 -- Rewrite N as a constant dummy value in the relevant type if possible.
212 Static
: Boolean := False;
213 Check_Elab
: Boolean := False);
214 -- Rewrite N as the result of evaluating Left <shift op> Right if possible.
215 -- Op represents the shift operation.
216 -- Static indicates whether the resulting node should be marked static.
217 -- Check_Elab indicates whether checks for elaboration calls should be
218 -- inserted when relevant.
220 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
;
221 -- Converts a bit string of length B'Length to a Uint value to be used for
222 -- a target of type T, which is a modular type. This procedure includes the
223 -- necessary reduction by the modulus in the case of a nonbinary modulus
224 -- (for a binary modulus, the bit string is the right length any way so all
227 function Get_String_Val
(N
: Node_Id
) return Node_Id
;
228 -- Given a tree node for a folded string or character value, returns the
229 -- corresponding string literal or character literal (one of the two must
230 -- be available, or the operand would not have been marked as foldable in
231 -- the earlier analysis of the operation).
233 function Is_OK_Static_Choice
(Choice
: Node_Id
) return Boolean;
234 -- Given a choice (from a case expression or membership test), returns
235 -- True if the choice is static and does not raise a Constraint_Error.
237 function Is_OK_Static_Choice_List
(Choices
: List_Id
) return Boolean;
238 -- Given a choice list (from a case expression or membership test), return
239 -- True if all choices are static in the sense of Is_OK_Static_Choice.
241 function Is_Static_Choice
(Choice
: Node_Id
) return Boolean;
242 -- Given a choice (from a case expression or membership test), returns
243 -- True if the choice is static. No test is made for raising of constraint
244 -- error, so this function is used only for legality tests.
246 function Is_Static_Choice_List
(Choices
: List_Id
) return Boolean;
247 -- Given a choice list (from a case expression or membership test), return
248 -- True if all choices are static in the sense of Is_Static_Choice.
250 function Is_Static_Range
(N
: Node_Id
) return Boolean;
251 -- Determine if range is static, as defined in RM 4.9(26). The only allowed
252 -- argument is an N_Range node (but note that the semantic analysis of
253 -- equivalent range attribute references already turned them into the
254 -- equivalent range). This differs from Is_OK_Static_Range (which is what
255 -- must be used by clients) in that it does not care whether the bounds
256 -- raise Constraint_Error or not. Used for checking whether expressions are
257 -- static in the 4.9 sense (without worrying about exceptions).
259 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean;
260 -- Bits represents the number of bits in an integer value to be computed
261 -- (but the value has not been computed yet). If this value in Bits is
262 -- reasonable, a result of True is returned, with the implication that the
263 -- caller should go ahead and complete the calculation. If the value in
264 -- Bits is unreasonably large, then an error is posted on node N, and
265 -- False is returned (and the caller skips the proposed calculation).
267 procedure Out_Of_Range
(N
: Node_Id
);
268 -- This procedure is called if it is determined that node N, which appears
269 -- in a non-static context, is a compile-time-known value which is outside
270 -- its range, i.e. the range of Etype. This is used in contexts where
271 -- this is an illegality if N is static, and should generate a warning
274 function Real_Or_String_Static_Predicate_Matches
276 Typ
: Entity_Id
) return Boolean;
277 -- This is the function used to evaluate real or string static predicates.
278 -- Val is an unanalyzed N_Real_Literal or N_String_Literal node, which
279 -- represents the value to be tested against the predicate. Typ is the
280 -- type with the predicate, from which the predicate expression can be
281 -- extracted. The result returned is True if the given value satisfies
284 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
);
285 -- N and Exp are nodes representing an expression, Exp is known to raise
286 -- CE. N is rewritten in term of Exp in the optimal way.
288 function String_Type_Len
(Stype
: Entity_Id
) return Uint
;
289 -- Given a string type, determines the length of the index type, or, if
290 -- this index type is non-static, the length of the base type of this index
291 -- type. Note that if the string type is itself static, then the index type
292 -- is static, so the second case applies only if the string type passed is
295 function Test
(Cond
: Boolean) return Uint
;
296 pragma Inline
(Test
);
297 -- This function simply returns the appropriate Boolean'Pos value
298 -- corresponding to the value of Cond as a universal integer. It is
299 -- used for producing the result of the static evaluation of the
302 procedure Test_Expression_Is_Foldable
307 -- Tests to see if expression N whose single operand is Op1 is foldable,
308 -- i.e. the operand value is known at compile time. If the operation is
309 -- foldable, then Fold is True on return, and Stat indicates whether the
310 -- result is static (i.e. the operand was static). Note that it is quite
311 -- possible for Fold to be True, and Stat to be False, since there are
312 -- cases in which we know the value of an operand even though it is not
313 -- technically static (e.g. the static lower bound of a range whose upper
314 -- bound is non-static).
316 -- If Stat is set False on return, then Test_Expression_Is_Foldable makes
317 -- a call to Check_Non_Static_Context on the operand. If Fold is False on
318 -- return, then all processing is complete, and the caller should return,
319 -- since there is nothing else to do.
321 -- If Stat is set True on return, then Is_Static_Expression is also set
322 -- true in node N. There are some cases where this is over-enthusiastic,
323 -- e.g. in the two operand case below, for string comparison, the result is
324 -- not static even though the two operands are static. In such cases, the
325 -- caller must reset the Is_Static_Expression flag in N.
327 -- If Fold and Stat are both set to False then this routine performs also
328 -- the following extra actions:
330 -- If either operand is Any_Type then propagate it to result to prevent
333 -- If some operand raises Constraint_Error, then replace the node N
334 -- with the raise Constraint_Error node. This replacement inherits the
335 -- Is_Static_Expression flag from the operands.
337 procedure Test_Expression_Is_Foldable
343 CRT_Safe
: Boolean := False);
344 -- Same processing, except applies to an expression N with two operands
345 -- Op1 and Op2. The result is static only if both operands are static. If
346 -- CRT_Safe is set True, then CRT_Safe_Compile_Time_Known_Value is used
347 -- for the tests that the two operands are known at compile time. See
348 -- spec of this routine for further details.
350 function Test_In_Range
353 Assume_Valid
: Boolean;
355 Int_Real
: Boolean) return Range_Membership
;
356 -- Common processing for Is_In_Range and Is_Out_Of_Range: Returns In_Range
357 -- or Out_Of_Range if it can be guaranteed at compile time that expression
358 -- N is known to be in or out of range of the subtype Typ. If not compile
359 -- time known, Unknown is returned. See documentation of Is_In_Range for
360 -- complete description of parameters.
362 procedure To_Bits
(U
: Uint
; B
: out Bits
);
363 -- Converts a Uint value to a bit string of length B'Length
365 -----------------------------------------------
366 -- Check_Expression_Against_Static_Predicate --
367 -----------------------------------------------
369 procedure Check_Expression_Against_Static_Predicate
372 Static_Failure_Is_Error
: Boolean := False)
375 -- Nothing to do if expression is not known at compile time, or the
376 -- type has no static predicate set (will be the case for all non-scalar
377 -- types, so no need to make a special test for that).
379 if not (Has_Static_Predicate
(Typ
)
380 and then Compile_Time_Known_Value
(Expr
))
385 -- Here we have a static predicate (note that it could have arisen from
386 -- an explicitly specified Dynamic_Predicate whose expression met the
387 -- rules for being predicate-static). If the expression is known at
388 -- compile time and obeys the predicate, then it is static and must be
389 -- labeled as such, which matters e.g. for case statements. The original
390 -- expression may be a type conversion of a variable with a known value,
391 -- which might otherwise not be marked static.
393 -- Case of real static predicate
395 if Is_Real_Type
(Typ
) then
396 if Real_Or_String_Static_Predicate_Matches
397 (Val
=> Make_Real_Literal
(Sloc
(Expr
), Expr_Value_R
(Expr
)),
400 Set_Is_Static_Expression
(Expr
);
404 -- Case of string static predicate
406 elsif Is_String_Type
(Typ
) then
407 if Real_Or_String_Static_Predicate_Matches
408 (Val
=> Expr_Value_S
(Expr
), Typ
=> Typ
)
410 Set_Is_Static_Expression
(Expr
);
414 -- Case of discrete static predicate
417 pragma Assert
(Is_Discrete_Type
(Typ
));
419 -- If static predicate matches, nothing to do
421 if Choices_Match
(Expr
, Static_Discrete_Predicate
(Typ
)) = Match
then
422 Set_Is_Static_Expression
(Expr
);
427 -- Here we know that the predicate will fail
429 -- Special case of static expression failing a predicate (other than one
430 -- that was explicitly specified with a Dynamic_Predicate aspect). If
431 -- the expression comes from a qualified_expression or type_conversion
432 -- this is an error (Static_Failure_Is_Error); otherwise we only issue
433 -- a warning and the expression is no longer considered static.
435 if Is_Static_Expression
(Expr
)
436 and then not Has_Dynamic_Predicate_Aspect
(Typ
)
438 if Static_Failure_Is_Error
then
440 ("static expression fails static predicate check on &",
445 ("??static expression fails static predicate check on &",
448 ("\??expression is no longer considered static", Expr
);
450 Set_Is_Static_Expression
(Expr
, False);
453 -- In all other cases, this is just a warning that a test will fail.
454 -- It does not matter if the expression is static or not, or if the
455 -- predicate comes from a dynamic predicate aspect or not.
459 ("??expression fails predicate check on &", Expr
, Typ
);
461 -- Force a check here, which is potentially a redundant check, but
462 -- this ensures a check will be done in cases where the expression
463 -- is folded, and since this is definitely a failure, extra checks
466 if Predicate_Enabled
(Typ
) then
469 (Typ
, Duplicate_Subexpr
(Expr
)), Suppress
=> All_Checks
);
472 end Check_Expression_Against_Static_Predicate
;
474 ------------------------------
475 -- Check_Non_Static_Context --
476 ------------------------------
478 procedure Check_Non_Static_Context
(N
: Node_Id
) is
479 T
: constant Entity_Id
:= Etype
(N
);
480 Checks_On
: constant Boolean :=
481 not Index_Checks_Suppressed
(T
)
482 and not Range_Checks_Suppressed
(T
);
485 -- Ignore cases of non-scalar types, error types, or universal real
486 -- types that have no usable bounds.
489 or else not Is_Scalar_Type
(T
)
490 or else T
= Universal_Fixed
491 or else T
= Universal_Real
496 -- At this stage we have a scalar type. If we have an expression that
497 -- raises CE, then we already issued a warning or error msg so there is
498 -- nothing more to be done in this routine.
500 if Raises_Constraint_Error
(N
) then
504 -- Now we have a scalar type which is not marked as raising a constraint
505 -- error exception. The main purpose of this routine is to deal with
506 -- static expressions appearing in a non-static context. That means
507 -- that if we do not have a static expression then there is not much
508 -- to do. The one case that we deal with here is that if we have a
509 -- floating-point value that is out of range, then we post a warning
510 -- that an infinity will result.
512 if not Is_Static_Expression
(N
) then
513 if Is_Floating_Point_Type
(T
) then
514 if Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
516 ("??float value out of range, infinity will be generated", N
);
518 -- The literal may be the result of constant-folding of a non-
519 -- static subexpression of a larger expression (e.g. a conversion
520 -- of a non-static variable whose value happens to be known). At
521 -- this point we must reduce the value of the subexpression to a
522 -- machine number (RM 4.9 (38/2)).
524 elsif Nkind
(N
) = N_Real_Literal
525 and then Nkind
(Parent
(N
)) in N_Subexpr
527 Rewrite
(N
, New_Copy
(N
));
528 Set_Realval
(N
, Machine_Number
(Base_Type
(T
), Realval
(N
), N
));
529 Set_Is_Machine_Number
(N
);
536 -- Here we have the case of outer level static expression of scalar
537 -- type, where the processing of this procedure is needed.
539 -- For real types, this is where we convert the value to a machine
540 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should only
541 -- need to do this if the parent is a constant declaration, since in
542 -- other cases, gigi should do the necessary conversion correctly, but
543 -- experimentation shows that this is not the case on all machines, in
544 -- particular if we do not convert all literals to machine values in
545 -- non-static contexts, then ACVC test C490001 fails on Sparc/Solaris
548 -- This conversion is always done by GNATprove on real literals in
549 -- non-static expressions, by calling Check_Non_Static_Context from
550 -- gnat2why, as GNATprove cannot do the conversion later contrary
551 -- to gigi. The frontend computes the information about which
552 -- expressions are static, which is used by gnat2why to call
553 -- Check_Non_Static_Context on exactly those real literals that are
554 -- not subexpressions of static expressions.
556 if Nkind
(N
) = N_Real_Literal
557 and then not Is_Machine_Number
(N
)
558 and then not Is_Generic_Type
(Etype
(N
))
559 and then Etype
(N
) /= Universal_Real
561 -- Check that value is in bounds before converting to machine
562 -- number, so as not to lose case where value overflows in the
563 -- least significant bit or less. See B490001.
565 if Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
570 -- Note: we have to copy the node, to avoid problems with conformance
571 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
573 Rewrite
(N
, New_Copy
(N
));
575 if not Is_Floating_Point_Type
(T
) then
577 (N
, Corresponding_Integer_Value
(N
) * Small_Value
(T
));
579 elsif not UR_Is_Zero
(Realval
(N
)) then
580 Set_Realval
(N
, Machine_Number
(Base_Type
(T
), Realval
(N
), N
));
581 Set_Is_Machine_Number
(N
);
586 -- Check for out of range universal integer. This is a non-static
587 -- context, so the integer value must be in range of the runtime
588 -- representation of universal integers.
590 -- We do this only within an expression, because that is the only
591 -- case in which non-static universal integer values can occur, and
592 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
593 -- called in contexts like the expression of a number declaration where
594 -- we certainly want to allow out of range values.
596 -- We inhibit the warning when expansion is disabled, because the
597 -- preanalysis of a range of a 64-bit modular type may appear to
598 -- violate the constraint on non-static Universal_Integer. If there
599 -- is a true overflow it will be diagnosed during full analysis.
601 if Etype
(N
) = Universal_Integer
602 and then Nkind
(N
) = N_Integer_Literal
603 and then Nkind
(Parent
(N
)) in N_Subexpr
604 and then Expander_Active
606 (Intval
(N
) < Expr_Value
(Type_Low_Bound
(Universal_Integer
))
608 Intval
(N
) > Expr_Value
(Type_High_Bound
(Universal_Integer
)))
610 Apply_Compile_Time_Constraint_Error
611 (N
, "non-static universal integer value out of range<<",
612 CE_Range_Check_Failed
);
614 -- Check out of range of base type
616 elsif Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
619 -- Give a warning or error on the value outside the subtype. A warning
620 -- is omitted if the expression appears in a range that could be null
621 -- (warnings are handled elsewhere for this case).
623 elsif T
/= Base_Type
(T
) and then Nkind
(Parent
(N
)) /= N_Range
then
624 if Is_In_Range
(N
, T
, Assume_Valid
=> True) then
627 elsif Is_Out_Of_Range
(N
, T
, Assume_Valid
=> True) then
628 -- Ignore out of range values for System.Priority in CodePeer
629 -- mode since the actual target compiler may provide a wider
632 if CodePeer_Mode
and then Is_RTE
(T
, RE_Priority
) then
633 Set_Do_Range_Check
(N
, False);
635 -- Determine if the out-of-range violation constitutes a warning
636 -- or an error based on context, according to RM 4.9 (34/3).
638 elsif Nkind
(Original_Node
(N
)) in
639 N_Type_Conversion | N_Qualified_Expression
640 and then Comes_From_Source
(Original_Node
(N
))
642 Apply_Compile_Time_Constraint_Error
643 (N
, "value not in range of}", CE_Range_Check_Failed
);
645 Apply_Compile_Time_Constraint_Error
646 (N
, "value not in range of}<<", CE_Range_Check_Failed
);
650 Enable_Range_Check
(N
);
653 Set_Do_Range_Check
(N
, False);
656 end Check_Non_Static_Context
;
658 -------------------------------------------
659 -- Check_Non_Static_Context_For_Overflow --
660 -------------------------------------------
662 procedure Check_Non_Static_Context_For_Overflow
668 if (not Stat
or else In_Inlined_Body
)
669 and then Is_Signed_Integer_Type
(Etype
(N
))
672 BT
: constant Entity_Id
:= Base_Type
(Etype
(N
));
673 Lo
: constant Uint
:= Expr_Value
(Type_Low_Bound
(BT
));
674 Hi
: constant Uint
:= Expr_Value
(Type_High_Bound
(BT
));
676 if Result
< Lo
or else Result
> Hi
then
677 Apply_Compile_Time_Constraint_Error
678 (N
, "value not in range of }??",
679 CE_Overflow_Check_Failed
,
684 end Check_Non_Static_Context_For_Overflow
;
686 ---------------------------------
687 -- Check_String_Literal_Length --
688 ---------------------------------
690 procedure Check_String_Literal_Length
(N
: Node_Id
; Ttype
: Entity_Id
) is
692 if not Raises_Constraint_Error
(N
) and then Is_Constrained
(Ttype
) then
693 if UI_From_Int
(String_Length
(Strval
(N
))) /= String_Type_Len
(Ttype
)
695 Apply_Compile_Time_Constraint_Error
696 (N
, "string length wrong for}??",
697 CE_Length_Check_Failed
,
702 end Check_String_Literal_Length
;
704 --------------------------------------------
705 -- Checking_Potentially_Static_Expression --
706 --------------------------------------------
708 function Checking_Potentially_Static_Expression
return Boolean is
710 return Checking_For_Potentially_Static_Expression
;
711 end Checking_Potentially_Static_Expression
;
717 function Choice_Matches
719 Choice
: Node_Id
) return Match_Result
721 Etyp
: constant Entity_Id
:= Etype
(Expr
);
727 pragma Assert
(Compile_Time_Known_Value
(Expr
));
728 pragma Assert
(Is_Scalar_Type
(Etyp
) or else Is_String_Type
(Etyp
));
730 if not Is_OK_Static_Choice
(Choice
) then
731 Set_Raises_Constraint_Error
(Choice
);
734 -- When the choice denotes a subtype with a static predictate, check the
735 -- expression against the predicate values. Different procedures apply
736 -- to discrete and non-discrete types.
738 elsif (Nkind
(Choice
) = N_Subtype_Indication
739 or else (Is_Entity_Name
(Choice
)
740 and then Is_Type
(Entity
(Choice
))))
741 and then Has_Predicates
(Etype
(Choice
))
742 and then Has_Static_Predicate
(Etype
(Choice
))
744 if Is_Discrete_Type
(Etype
(Choice
)) then
747 (Expr
, Static_Discrete_Predicate
(Etype
(Choice
)));
749 elsif Real_Or_String_Static_Predicate_Matches
(Expr
, Etype
(Choice
))
757 -- Discrete type case only
759 elsif Is_Discrete_Type
(Etyp
) then
760 Val
:= Expr_Value
(Expr
);
762 if Nkind
(Choice
) = N_Range
then
763 if Val
>= Expr_Value
(Low_Bound
(Choice
))
765 Val
<= Expr_Value
(High_Bound
(Choice
))
772 elsif Nkind
(Choice
) = N_Subtype_Indication
773 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
775 if Val
>= Expr_Value
(Type_Low_Bound
(Etype
(Choice
)))
777 Val
<= Expr_Value
(Type_High_Bound
(Etype
(Choice
)))
784 elsif Nkind
(Choice
) = N_Others_Choice
then
788 if Val
= Expr_Value
(Choice
) then
797 elsif Is_Real_Type
(Etyp
) then
798 ValR
:= Expr_Value_R
(Expr
);
800 if Nkind
(Choice
) = N_Range
then
801 if ValR
>= Expr_Value_R
(Low_Bound
(Choice
))
803 ValR
<= Expr_Value_R
(High_Bound
(Choice
))
810 elsif Nkind
(Choice
) = N_Subtype_Indication
811 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
813 if ValR
>= Expr_Value_R
(Type_Low_Bound
(Etype
(Choice
)))
815 ValR
<= Expr_Value_R
(Type_High_Bound
(Etype
(Choice
)))
823 if ValR
= Expr_Value_R
(Choice
) then
833 pragma Assert
(Is_String_Type
(Etyp
));
834 ValS
:= Expr_Value_S
(Expr
);
836 if Nkind
(Choice
) = N_Subtype_Indication
837 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
839 if not Is_Constrained
(Etype
(Choice
)) then
844 Typlen
: constant Uint
:=
845 String_Type_Len
(Etype
(Choice
));
846 Strlen
: constant Uint
:=
847 UI_From_Int
(String_Length
(Strval
(ValS
)));
849 if Typlen
= Strlen
then
858 if String_Equal
(Strval
(ValS
), Strval
(Expr_Value_S
(Choice
)))
872 function Choices_Match
874 Choices
: List_Id
) return Match_Result
877 Result
: Match_Result
;
880 Choice
:= First
(Choices
);
881 while Present
(Choice
) loop
882 Result
:= Choice_Matches
(Expr
, Choice
);
884 if Result
/= No_Match
then
894 --------------------------
895 -- Compile_Time_Compare --
896 --------------------------
898 function Compile_Time_Compare
900 Assume_Valid
: Boolean) return Compare_Result
902 Discard
: aliased Uint
;
904 return Compile_Time_Compare
(L
, R
, Discard
'Access, Assume_Valid
);
905 end Compile_Time_Compare
;
907 function Compile_Time_Compare
910 Assume_Valid
: Boolean;
911 Rec
: Boolean := False) return Compare_Result
913 Ltyp
: Entity_Id
:= Etype
(L
);
914 Rtyp
: Entity_Id
:= Etype
(R
);
916 Discard
: aliased Uint
;
918 procedure Compare_Decompose
922 -- This procedure decomposes the node N into an expression node and a
923 -- signed offset, so that the value of N is equal to the value of R plus
924 -- the value V (which may be negative). If no such decomposition is
925 -- possible, then on return R is a copy of N, and V is set to zero.
927 function Compare_Fixup
(N
: Node_Id
) return Node_Id
;
928 -- This function deals with replacing 'Last and 'First references with
929 -- their corresponding type bounds, which we then can compare. The
930 -- argument is the original node, the result is the identity, unless we
931 -- have a 'Last/'First reference in which case the value returned is the
932 -- appropriate type bound.
934 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean;
935 -- Even if the context does not assume that values are valid, some
936 -- simple cases can be recognized.
938 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean;
939 -- Returns True iff L and R represent expressions that definitely have
940 -- identical (but not necessarily compile-time-known) values Indeed the
941 -- caller is expected to have already dealt with the cases of compile
942 -- time known values, so these are not tested here.
944 -----------------------
945 -- Compare_Decompose --
946 -----------------------
948 procedure Compare_Decompose
954 if Nkind
(N
) = N_Op_Add
955 and then Nkind
(Right_Opnd
(N
)) = N_Integer_Literal
958 V
:= Intval
(Right_Opnd
(N
));
961 elsif Nkind
(N
) = N_Op_Subtract
962 and then Nkind
(Right_Opnd
(N
)) = N_Integer_Literal
965 V
:= UI_Negate
(Intval
(Right_Opnd
(N
)));
968 elsif Nkind
(N
) = N_Attribute_Reference
then
969 if Attribute_Name
(N
) = Name_Succ
then
970 R
:= First
(Expressions
(N
));
974 elsif Attribute_Name
(N
) = Name_Pred
then
975 R
:= First
(Expressions
(N
));
983 end Compare_Decompose
;
989 function Compare_Fixup
(N
: Node_Id
) return Node_Id
is
995 -- Fixup only required for First/Last attribute reference
997 if Nkind
(N
) = N_Attribute_Reference
998 and then Attribute_Name
(N
) in Name_First | Name_Last
1000 Xtyp
:= Etype
(Prefix
(N
));
1002 -- If we have no type, then just abandon the attempt to do
1003 -- a fixup, this is probably the result of some other error.
1009 -- Dereference an access type
1011 if Is_Access_Type
(Xtyp
) then
1012 Xtyp
:= Designated_Type
(Xtyp
);
1015 -- If we don't have an array type at this stage, something is
1016 -- peculiar, e.g. another error, and we abandon the attempt at
1019 if not Is_Array_Type
(Xtyp
) then
1023 -- Ignore unconstrained array, since bounds are not meaningful
1025 if not Is_Constrained
(Xtyp
) then
1029 if Ekind
(Xtyp
) = E_String_Literal_Subtype
then
1030 if Attribute_Name
(N
) = Name_First
then
1031 return String_Literal_Low_Bound
(Xtyp
);
1034 Make_Integer_Literal
(Sloc
(N
),
1035 Intval
=> Intval
(String_Literal_Low_Bound
(Xtyp
)) +
1036 String_Literal_Length
(Xtyp
));
1040 -- Find correct index type
1042 Indx
:= First_Index
(Xtyp
);
1044 if Present
(Expressions
(N
)) then
1045 Subs
:= UI_To_Int
(Expr_Value
(First
(Expressions
(N
))));
1047 for J
in 2 .. Subs
loop
1052 Xtyp
:= Etype
(Indx
);
1054 if Attribute_Name
(N
) = Name_First
then
1055 return Type_Low_Bound
(Xtyp
);
1057 return Type_High_Bound
(Xtyp
);
1064 ----------------------------
1065 -- Is_Known_Valid_Operand --
1066 ----------------------------
1068 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean is
1070 return (Is_Entity_Name
(Opnd
)
1072 (Is_Known_Valid
(Entity
(Opnd
))
1073 or else Ekind
(Entity
(Opnd
)) = E_In_Parameter
1075 (Is_Object
(Entity
(Opnd
))
1076 and then Present
(Current_Value
(Entity
(Opnd
))))))
1077 or else Is_OK_Static_Expression
(Opnd
);
1078 end Is_Known_Valid_Operand
;
1084 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean is
1085 Lf
: constant Node_Id
:= Compare_Fixup
(L
);
1086 Rf
: constant Node_Id
:= Compare_Fixup
(R
);
1088 function Is_Rewritten_Loop_Entry
(N
: Node_Id
) return Boolean;
1089 -- An attribute reference to Loop_Entry may have been rewritten into
1090 -- its prefix as a way to avoid generating a constant for that
1091 -- attribute when the corresponding pragma is ignored. These nodes
1092 -- should be ignored when deciding if they can be equal to one
1095 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean;
1096 -- L, R are the Expressions values from two attribute nodes for First
1097 -- or Last attributes. Either may be set to No_List if no expressions
1098 -- are present (indicating subscript 1). The result is True if both
1099 -- expressions represent the same subscript (note one case is where
1100 -- one subscript is missing and the other is explicitly set to 1).
1102 -----------------------------
1103 -- Is_Rewritten_Loop_Entry --
1104 -----------------------------
1106 function Is_Rewritten_Loop_Entry
(N
: Node_Id
) return Boolean is
1107 Orig_N
: constant Node_Id
:= Original_Node
(N
);
1110 and then Nkind
(Orig_N
) = N_Attribute_Reference
1111 and then Get_Attribute_Id
(Attribute_Name
(Orig_N
)) =
1112 Attribute_Loop_Entry
;
1113 end Is_Rewritten_Loop_Entry
;
1115 -----------------------
1116 -- Is_Same_Subscript --
1117 -----------------------
1119 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean is
1125 return Expr_Value
(First
(R
)) = Uint_1
;
1130 return Expr_Value
(First
(L
)) = Uint_1
;
1132 return Expr_Value
(First
(L
)) = Expr_Value
(First
(R
));
1135 end Is_Same_Subscript
;
1137 -- Start of processing for Is_Same_Value
1140 -- Loop_Entry nodes rewritten into their prefix inside ignored
1141 -- pragmas should never lead to a decision of equality.
1143 if Is_Rewritten_Loop_Entry
(Lf
)
1144 or else Is_Rewritten_Loop_Entry
(Rf
)
1148 -- Values are the same if they refer to the same entity and the
1149 -- entity is nonvolatile.
1151 elsif Nkind
(Lf
) in N_Identifier | N_Expanded_Name
1152 and then Nkind
(Rf
) in N_Identifier | N_Expanded_Name
1153 and then Entity
(Lf
) = Entity
(Rf
)
1155 -- If the entity is a discriminant, the two expressions may be
1156 -- bounds of components of objects of the same discriminated type.
1157 -- The values of the discriminants are not static, and therefore
1158 -- the result is unknown.
1160 and then Ekind
(Entity
(Lf
)) /= E_Discriminant
1161 and then Present
(Entity
(Lf
))
1163 -- This does not however apply to Float types, since we may have
1164 -- two NaN values and they should never compare equal.
1166 and then not Is_Floating_Point_Type
(Etype
(L
))
1167 and then not Is_Volatile_Reference
(L
)
1168 and then not Is_Volatile_Reference
(R
)
1172 -- Or if they are compile-time-known and identical
1174 elsif Compile_Time_Known_Value
(Lf
)
1176 Compile_Time_Known_Value
(Rf
)
1177 and then Expr_Value
(Lf
) = Expr_Value
(Rf
)
1181 -- False if Nkind of the two nodes is different for remaining cases
1183 elsif Nkind
(Lf
) /= Nkind
(Rf
) then
1186 -- True if both 'First or 'Last values applying to the same entity
1187 -- (first and last don't change even if value does). Note that we
1188 -- need this even with the calls to Compare_Fixup, to handle the
1189 -- case of unconstrained array attributes where Compare_Fixup
1190 -- cannot find useful bounds.
1192 elsif Nkind
(Lf
) = N_Attribute_Reference
1193 and then Attribute_Name
(Lf
) = Attribute_Name
(Rf
)
1194 and then Attribute_Name
(Lf
) in Name_First | Name_Last
1195 and then Nkind
(Prefix
(Lf
)) in N_Identifier | N_Expanded_Name
1196 and then Nkind
(Prefix
(Rf
)) in N_Identifier | N_Expanded_Name
1197 and then Entity
(Prefix
(Lf
)) = Entity
(Prefix
(Rf
))
1198 and then Is_Same_Subscript
(Expressions
(Lf
), Expressions
(Rf
))
1202 -- True if the same selected component from the same record
1204 elsif Nkind
(Lf
) = N_Selected_Component
1205 and then Selector_Name
(Lf
) = Selector_Name
(Rf
)
1206 and then Is_Same_Value
(Prefix
(Lf
), Prefix
(Rf
))
1210 -- True if the same unary operator applied to the same operand
1212 elsif Nkind
(Lf
) in N_Unary_Op
1213 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
1217 -- True if the same binary operator applied to the same operands
1219 elsif Nkind
(Lf
) in N_Binary_Op
1220 and then Is_Same_Value
(Left_Opnd
(Lf
), Left_Opnd
(Rf
))
1221 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
1225 -- All other cases, we can't tell, so return False
1232 -- Start of processing for Compile_Time_Compare
1235 Diff
.all := No_Uint
;
1237 -- In preanalysis mode, always return Unknown unless the expression
1238 -- is static. It is too early to be thinking we know the result of a
1239 -- comparison, save that judgment for the full analysis. This is
1240 -- particularly important in the case of pre and postconditions, which
1241 -- otherwise can be prematurely collapsed into having True or False
1242 -- conditions when this is inappropriate.
1244 if not (Full_Analysis
1245 or else (Is_OK_Static_Expression
(L
)
1247 Is_OK_Static_Expression
(R
)))
1252 -- If either operand could raise Constraint_Error, then we cannot
1253 -- know the result at compile time (since CE may be raised).
1255 if not (Cannot_Raise_Constraint_Error
(L
)
1257 Cannot_Raise_Constraint_Error
(R
))
1262 -- Identical operands are most certainly equal
1268 -- If expressions have no types, then do not attempt to determine if
1269 -- they are the same, since something funny is going on. One case in
1270 -- which this happens is during generic template analysis, when bounds
1271 -- are not fully analyzed.
1273 if No
(Ltyp
) or else No
(Rtyp
) then
1277 -- These get reset to the base type for the case of entities where
1278 -- Is_Known_Valid is not set. This takes care of handling possible
1279 -- invalid representations using the value of the base type, in
1280 -- accordance with RM 13.9.1(10).
1282 Ltyp
:= Underlying_Type
(Ltyp
);
1283 Rtyp
:= Underlying_Type
(Rtyp
);
1285 -- Same rationale as above, but for Underlying_Type instead of Etype
1287 if No
(Ltyp
) or else No
(Rtyp
) then
1291 -- We do not attempt comparisons for packed arrays represented as
1292 -- modular types, where the semantics of comparison is quite different.
1294 if Is_Packed_Array_Impl_Type
(Ltyp
)
1295 and then Is_Modular_Integer_Type
(Ltyp
)
1299 -- For access types, the only time we know the result at compile time
1300 -- (apart from identical operands, which we handled already) is if we
1301 -- know one operand is null and the other is not, or both operands are
1304 elsif Is_Access_Type
(Ltyp
) then
1305 if Known_Null
(L
) then
1306 if Known_Null
(R
) then
1308 elsif Known_Non_Null
(R
) then
1314 elsif Known_Non_Null
(L
) and then Known_Null
(R
) then
1321 -- Case where comparison involves two compile-time-known values
1323 elsif Compile_Time_Known_Value
(L
)
1325 Compile_Time_Known_Value
(R
)
1327 -- For the floating-point case, we have to be a little careful, since
1328 -- at compile time we are dealing with universal exact values, but at
1329 -- runtime, these will be in non-exact target form. That's why the
1330 -- returned results are LE and GE below instead of LT and GT.
1332 if Is_Floating_Point_Type
(Ltyp
)
1334 Is_Floating_Point_Type
(Rtyp
)
1337 Lo
: constant Ureal
:= Expr_Value_R
(L
);
1338 Hi
: constant Ureal
:= Expr_Value_R
(R
);
1349 -- For string types, we have two string literals and we proceed to
1350 -- compare them using the Ada style dictionary string comparison.
1352 elsif not Is_Scalar_Type
(Ltyp
) then
1354 Lstring
: constant String_Id
:= Strval
(Expr_Value_S
(L
));
1355 Rstring
: constant String_Id
:= Strval
(Expr_Value_S
(R
));
1356 Llen
: constant Nat
:= String_Length
(Lstring
);
1357 Rlen
: constant Nat
:= String_Length
(Rstring
);
1360 for J
in 1 .. Nat
'Min (Llen
, Rlen
) loop
1362 LC
: constant Char_Code
:= Get_String_Char
(Lstring
, J
);
1363 RC
: constant Char_Code
:= Get_String_Char
(Rstring
, J
);
1375 elsif Llen
> Rlen
then
1382 -- For remaining scalar cases we know exactly (note that this does
1383 -- include the fixed-point case, where we know the run time integer
1388 Lo
: constant Uint
:= Expr_Value
(L
);
1389 Hi
: constant Uint
:= Expr_Value
(R
);
1392 Diff
.all := Hi
- Lo
;
1397 Diff
.all := Lo
- Hi
;
1403 -- Cases where at least one operand is not known at compile time
1406 -- Remaining checks apply only for discrete types
1408 if not Is_Discrete_Type
(Ltyp
)
1410 not Is_Discrete_Type
(Rtyp
)
1415 -- Defend against generic types, or actually any expressions that
1416 -- contain a reference to a generic type from within a generic
1417 -- template. We don't want to do any range analysis of such
1418 -- expressions for two reasons. First, the bounds of a generic type
1419 -- itself are junk and cannot be used for any kind of analysis.
1420 -- Second, we may have a case where the range at run time is indeed
1421 -- known, but we don't want to do compile time analysis in the
1422 -- template based on that range since in an instance the value may be
1423 -- static, and able to be elaborated without reference to the bounds
1424 -- of types involved. As an example, consider:
1426 -- (F'Pos (F'Last) + 1) > Integer'Last
1428 -- The expression on the left side of > is Universal_Integer and thus
1429 -- acquires the type Integer for evaluation at run time, and at run
1430 -- time it is true that this condition is always False, but within
1431 -- an instance F may be a type with a static range greater than the
1432 -- range of Integer, and the expression statically evaluates to True.
1434 if References_Generic_Formal_Type
(L
)
1436 References_Generic_Formal_Type
(R
)
1441 -- Replace types by base types for the case of values which are not
1442 -- known to have valid representations. This takes care of properly
1443 -- dealing with invalid representations.
1445 if not Assume_Valid
then
1446 if not (Is_Entity_Name
(L
)
1447 and then (Is_Known_Valid
(Entity
(L
))
1448 or else Assume_No_Invalid_Values
))
1450 Ltyp
:= Underlying_Type
(Base_Type
(Ltyp
));
1453 if not (Is_Entity_Name
(R
)
1454 and then (Is_Known_Valid
(Entity
(R
))
1455 or else Assume_No_Invalid_Values
))
1457 Rtyp
:= Underlying_Type
(Base_Type
(Rtyp
));
1461 -- First attempt is to decompose the expressions to extract a
1462 -- constant offset resulting from the use of any of the forms:
1469 -- Then we see if the two expressions are the same value, and if so
1470 -- the result is obtained by comparing the offsets.
1472 -- Note: the reason we do this test first is that it returns only
1473 -- decisive results (with diff set), where other tests, like the
1474 -- range test, may not be as so decisive. Consider for example
1475 -- J .. J + 1. This code can conclude LT with a difference of 1,
1476 -- even if the range of J is not known.
1485 Compare_Decompose
(L
, Lnode
, Loffs
);
1486 Compare_Decompose
(R
, Rnode
, Roffs
);
1488 if Is_Same_Value
(Lnode
, Rnode
) then
1489 if Loffs
= Roffs
then
1493 -- When the offsets are not equal, we can go farther only if
1494 -- the types are not modular (e.g. X < X + 1 is False if X is
1495 -- the largest number).
1497 if not Is_Modular_Integer_Type
(Ltyp
)
1498 and then not Is_Modular_Integer_Type
(Rtyp
)
1500 if Loffs
< Roffs
then
1501 Diff
.all := Roffs
- Loffs
;
1504 Diff
.all := Loffs
- Roffs
;
1511 -- Next, try range analysis and see if operand ranges are disjoint
1519 -- True if each range is a single point
1522 Determine_Range
(L
, LOK
, LLo
, LHi
, Assume_Valid
);
1523 Determine_Range
(R
, ROK
, RLo
, RHi
, Assume_Valid
);
1526 Single
:= LLo
= LHi
and then RLo
= RHi
;
1529 if Single
and Assume_Valid
then
1530 Diff
.all := RLo
- LLo
;
1535 elsif RHi
< LLo
then
1536 if Single
and Assume_Valid
then
1537 Diff
.all := LLo
- RLo
;
1542 elsif Single
and then LLo
= RLo
then
1544 -- If the range includes a single literal and we can assume
1545 -- validity then the result is known even if an operand is
1548 if Assume_Valid
then
1554 elsif LHi
= RLo
then
1557 elsif RHi
= LLo
then
1560 elsif not Is_Known_Valid_Operand
(L
)
1561 and then not Assume_Valid
1563 if Is_Same_Value
(L
, R
) then
1570 -- If the range of either operand cannot be determined, nothing
1571 -- further can be inferred.
1578 -- Here is where we check for comparisons against maximum bounds of
1579 -- types, where we know that no value can be outside the bounds of
1580 -- the subtype. Note that this routine is allowed to assume that all
1581 -- expressions are within their subtype bounds. Callers wishing to
1582 -- deal with possibly invalid values must in any case take special
1583 -- steps (e.g. conversions to larger types) to avoid this kind of
1584 -- optimization, which is always considered to be valid. We do not
1585 -- attempt this optimization with generic types, since the type
1586 -- bounds may not be meaningful in this case.
1588 -- We are in danger of an infinite recursion here. It does not seem
1589 -- useful to go more than one level deep, so the parameter Rec is
1590 -- used to protect ourselves against this infinite recursion.
1594 -- See if we can get a decisive check against one operand and a
1595 -- bound of the other operand (four possible tests here). Note
1596 -- that we avoid testing junk bounds of a generic type.
1598 if not Is_Generic_Type
(Rtyp
) then
1599 case Compile_Time_Compare
(L
, Type_Low_Bound
(Rtyp
),
1601 Assume_Valid
, Rec
=> True)
1603 when LT
=> return LT
;
1604 when LE
=> return LE
;
1605 when EQ
=> return LE
;
1606 when others => null;
1609 case Compile_Time_Compare
(L
, Type_High_Bound
(Rtyp
),
1611 Assume_Valid
, Rec
=> True)
1613 when GT
=> return GT
;
1614 when GE
=> return GE
;
1615 when EQ
=> return GE
;
1616 when others => null;
1620 if not Is_Generic_Type
(Ltyp
) then
1621 case Compile_Time_Compare
(Type_Low_Bound
(Ltyp
), R
,
1623 Assume_Valid
, Rec
=> True)
1625 when GT
=> return GT
;
1626 when GE
=> return GE
;
1627 when EQ
=> return GE
;
1628 when others => null;
1631 case Compile_Time_Compare
(Type_High_Bound
(Ltyp
), R
,
1633 Assume_Valid
, Rec
=> True)
1635 when LT
=> return LT
;
1636 when LE
=> return LE
;
1637 when EQ
=> return LE
;
1638 when others => null;
1643 -- Next attempt is to see if we have an entity compared with a
1644 -- compile-time-known value, where there is a current value
1645 -- conditional for the entity which can tell us the result.
1649 -- Entity variable (left operand)
1652 -- Value (right operand)
1655 -- If False, we have reversed the operands
1658 -- Comparison operator kind from Get_Current_Value_Condition call
1661 -- Value from Get_Current_Value_Condition call
1666 Result
: Compare_Result
;
1667 -- Known result before inversion
1670 if Is_Entity_Name
(L
)
1671 and then Compile_Time_Known_Value
(R
)
1674 Val
:= Expr_Value
(R
);
1677 elsif Is_Entity_Name
(R
)
1678 and then Compile_Time_Known_Value
(L
)
1681 Val
:= Expr_Value
(L
);
1684 -- That was the last chance at finding a compile time result
1690 Get_Current_Value_Condition
(Var
, Op
, Opn
);
1692 -- That was the last chance, so if we got nothing return
1698 Opv
:= Expr_Value
(Opn
);
1700 -- We got a comparison, so we might have something interesting
1702 -- Convert LE to LT and GE to GT, just so we have fewer cases
1704 if Op
= N_Op_Le
then
1708 elsif Op
= N_Op_Ge
then
1713 -- Deal with equality case
1715 if Op
= N_Op_Eq
then
1718 elsif Opv
< Val
then
1724 -- Deal with inequality case
1726 elsif Op
= N_Op_Ne
then
1733 -- Deal with greater than case
1735 elsif Op
= N_Op_Gt
then
1738 elsif Opv
= Val
- 1 then
1744 -- Deal with less than case
1746 else pragma Assert
(Op
= N_Op_Lt
);
1749 elsif Opv
= Val
+ 1 then
1756 -- Deal with inverting result
1760 when GT
=> return LT
;
1761 when GE
=> return LE
;
1762 when LT
=> return GT
;
1763 when LE
=> return GE
;
1764 when others => return Result
;
1771 end Compile_Time_Compare
;
1773 -------------------------------
1774 -- Compile_Time_Known_Bounds --
1775 -------------------------------
1777 function Compile_Time_Known_Bounds
(T
: Entity_Id
) return Boolean is
1782 if T
= Any_Composite
or else not Is_Array_Type
(T
) then
1786 Indx
:= First_Index
(T
);
1787 while Present
(Indx
) loop
1788 Typ
:= Underlying_Type
(Etype
(Indx
));
1790 -- Never look at junk bounds of a generic type
1792 if Is_Generic_Type
(Typ
) then
1796 -- Otherwise check bounds for compile-time-known
1798 if not Compile_Time_Known_Value
(Type_Low_Bound
(Typ
)) then
1800 elsif not Compile_Time_Known_Value
(Type_High_Bound
(Typ
)) then
1808 end Compile_Time_Known_Bounds
;
1810 ------------------------------
1811 -- Compile_Time_Known_Value --
1812 ------------------------------
1814 function Compile_Time_Known_Value
(Op
: Node_Id
) return Boolean is
1815 K
: constant Node_Kind
:= Nkind
(Op
);
1816 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(Op
) mod CV_Cache_Size
);
1819 -- Never known at compile time if bad type or raises Constraint_Error
1820 -- or empty (which can occur as a result of a previous error or in the
1821 -- case of e.g. an imported constant).
1827 or else Nkind
(Op
) not in N_Has_Etype
1828 or else Etype
(Op
) = Any_Type
1829 or else Raises_Constraint_Error
(Op
)
1834 -- If we have an entity name, then see if it is the name of a constant
1835 -- and if so, test the corresponding constant value, or the name of an
1836 -- enumeration literal, which is always a constant.
1838 if Present
(Etype
(Op
)) and then Is_Entity_Name
(Op
) then
1840 Ent
: constant Entity_Id
:= Entity
(Op
);
1844 -- Never known at compile time if it is a packed array value. We
1845 -- might want to try to evaluate these at compile time one day,
1846 -- but we do not make that attempt now.
1848 if Is_Packed_Array_Impl_Type
(Etype
(Op
)) then
1851 elsif Ekind
(Ent
) = E_Enumeration_Literal
then
1854 elsif Ekind
(Ent
) = E_Constant
then
1855 Val
:= Constant_Value
(Ent
);
1857 if Present
(Val
) then
1859 -- Guard against an illegal deferred constant whose full
1860 -- view is initialized with a reference to itself. Treat
1861 -- this case as a value not known at compile time.
1863 if Is_Entity_Name
(Val
) and then Entity
(Val
) = Ent
then
1866 return Compile_Time_Known_Value
(Val
);
1869 -- Otherwise, the constant does not have a compile-time-known
1878 -- We have a value, see if it is compile-time-known
1881 -- Integer literals are worth storing in the cache
1883 if K
= N_Integer_Literal
then
1885 CV_Ent
.V
:= Intval
(Op
);
1888 -- Other literals and NULL are known at compile time
1891 N_Character_Literal | N_Real_Literal | N_String_Literal | N_Null
1895 -- Evaluate static discriminants, to eliminate dead paths and
1896 -- redundant discriminant checks.
1898 elsif Is_Static_Discriminant_Component
(Op
) then
1903 -- If we fall through, not known at compile time
1907 -- If we get an exception while trying to do this test, then some error
1908 -- has occurred, and we simply say that the value is not known after all
1912 -- With debug flag K we will get an exception unless an error has
1913 -- already occurred (useful for debugging).
1915 if Debug_Flag_K
then
1916 Check_Error_Detected
;
1920 end Compile_Time_Known_Value
;
1922 ---------------------------------------
1923 -- CRT_Safe_Compile_Time_Known_Value --
1924 ---------------------------------------
1926 function CRT_Safe_Compile_Time_Known_Value
(Op
: Node_Id
) return Boolean is
1928 if (Configurable_Run_Time_Mode
or No_Run_Time_Mode
)
1929 and then not Is_OK_Static_Expression
(Op
)
1933 return Compile_Time_Known_Value
(Op
);
1935 end CRT_Safe_Compile_Time_Known_Value
;
1941 -- This is only called for actuals of functions that are not predefined
1942 -- operators (which have already been rewritten as operators at this
1943 -- stage), so the call can never be folded, and all that needs doing for
1944 -- the actual is to do the check for a non-static context.
1946 procedure Eval_Actual
(N
: Node_Id
) is
1948 Check_Non_Static_Context
(N
);
1951 --------------------
1952 -- Eval_Allocator --
1953 --------------------
1955 -- Allocators are never static, so all we have to do is to do the
1956 -- check for a non-static context if an expression is present.
1958 procedure Eval_Allocator
(N
: Node_Id
) is
1959 Expr
: constant Node_Id
:= Expression
(N
);
1961 if Nkind
(Expr
) = N_Qualified_Expression
then
1962 Check_Non_Static_Context
(Expression
(Expr
));
1966 ------------------------
1967 -- Eval_Arithmetic_Op --
1968 ------------------------
1970 -- Arithmetic operations are static functions, so the result is static
1971 -- if both operands are static (RM 4.9(7), 4.9(20)).
1973 procedure Eval_Arithmetic_Op
(N
: Node_Id
) is
1974 Left
: constant Node_Id
:= Left_Opnd
(N
);
1975 Right
: constant Node_Id
:= Right_Opnd
(N
);
1976 Ltype
: constant Entity_Id
:= Etype
(Left
);
1977 Rtype
: constant Entity_Id
:= Etype
(Right
);
1978 Otype
: Entity_Id
:= Empty
;
1983 -- If not foldable we are done
1985 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
1991 -- Otherwise attempt to fold
1993 if Is_Universal_Numeric_Type
(Etype
(Left
))
1995 Is_Universal_Numeric_Type
(Etype
(Right
))
1997 Otype
:= Find_Universal_Operator_Type
(N
);
2000 -- Fold for cases where both operands are of integer type
2002 if Is_Integer_Type
(Ltype
) and then Is_Integer_Type
(Rtype
) then
2004 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2005 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2011 Result
:= Left_Int
+ Right_Int
;
2013 when N_Op_Subtract
=>
2014 Result
:= Left_Int
- Right_Int
;
2016 when N_Op_Multiply
=>
2019 (Num_Bits
(Left_Int
) + Num_Bits
(Right_Int
)))
2021 Result
:= Left_Int
* Right_Int
;
2028 -- The exception Constraint_Error is raised by integer
2029 -- division, rem and mod if the right operand is zero.
2031 if Right_Int
= 0 then
2033 -- When SPARK_Mode is On, force a warning instead of
2034 -- an error in that case, as this likely corresponds
2035 -- to deactivated code.
2037 Apply_Compile_Time_Constraint_Error
2038 (N
, "division by zero", CE_Divide_By_Zero
,
2039 Loc
=> Sloc
(Right
),
2040 Warn
=> not Stat
or SPARK_Mode
= On
);
2043 -- Otherwise we can do the division
2046 Result
:= Left_Int
/ Right_Int
;
2051 -- The exception Constraint_Error is raised by integer
2052 -- division, rem and mod if the right operand is zero.
2054 if Right_Int
= 0 then
2056 -- When SPARK_Mode is On, force a warning instead of
2057 -- an error in that case, as this likely corresponds
2058 -- to deactivated code.
2060 Apply_Compile_Time_Constraint_Error
2061 (N
, "mod with zero divisor", CE_Divide_By_Zero
,
2062 Loc
=> Sloc
(Right
),
2063 Warn
=> not Stat
or SPARK_Mode
= On
);
2067 Result
:= Left_Int
mod Right_Int
;
2072 -- The exception Constraint_Error is raised by integer
2073 -- division, rem and mod if the right operand is zero.
2075 if Right_Int
= 0 then
2077 -- When SPARK_Mode is On, force a warning instead of
2078 -- an error in that case, as this likely corresponds
2079 -- to deactivated code.
2081 Apply_Compile_Time_Constraint_Error
2082 (N
, "rem with zero divisor", CE_Divide_By_Zero
,
2083 Loc
=> Sloc
(Right
),
2084 Warn
=> not Stat
or SPARK_Mode
= On
);
2088 Result
:= Left_Int
rem Right_Int
;
2092 raise Program_Error
;
2095 -- Adjust the result by the modulus if the type is a modular type
2097 if Is_Modular_Integer_Type
(Ltype
) then
2098 Result
:= Result
mod Modulus
(Ltype
);
2101 Check_Non_Static_Context_For_Overflow
(N
, Stat
, Result
);
2103 -- If we get here we can fold the result
2105 Fold_Uint
(N
, Result
, Stat
);
2108 -- Cases where at least one operand is a real. We handle the cases of
2109 -- both reals, or mixed/real integer cases (the latter happen only for
2110 -- divide and multiply, and the result is always real).
2112 elsif Is_Real_Type
(Ltype
) or else Is_Real_Type
(Rtype
) then
2119 if Is_Real_Type
(Ltype
) then
2120 Left_Real
:= Expr_Value_R
(Left
);
2122 Left_Real
:= UR_From_Uint
(Expr_Value
(Left
));
2125 if Is_Real_Type
(Rtype
) then
2126 Right_Real
:= Expr_Value_R
(Right
);
2128 Right_Real
:= UR_From_Uint
(Expr_Value
(Right
));
2131 if Nkind
(N
) = N_Op_Add
then
2132 Result
:= Left_Real
+ Right_Real
;
2134 elsif Nkind
(N
) = N_Op_Subtract
then
2135 Result
:= Left_Real
- Right_Real
;
2137 elsif Nkind
(N
) = N_Op_Multiply
then
2138 Result
:= Left_Real
* Right_Real
;
2140 else pragma Assert
(Nkind
(N
) = N_Op_Divide
);
2141 if UR_Is_Zero
(Right_Real
) then
2142 Apply_Compile_Time_Constraint_Error
2143 (N
, "division by zero", CE_Divide_By_Zero
,
2144 Loc
=> Sloc
(Right
));
2148 Result
:= Left_Real
/ Right_Real
;
2151 Fold_Ureal
(N
, Result
, Stat
);
2155 -- If the operator was resolved to a specific type, make sure that type
2156 -- is frozen even if the expression is folded into a literal (which has
2157 -- a universal type).
2159 if Present
(Otype
) then
2160 Freeze_Before
(N
, Otype
);
2162 end Eval_Arithmetic_Op
;
2164 ----------------------------
2165 -- Eval_Character_Literal --
2166 ----------------------------
2168 -- Nothing to be done
2170 procedure Eval_Character_Literal
(N
: Node_Id
) is
2171 pragma Warnings
(Off
, N
);
2174 end Eval_Character_Literal
;
2180 -- Static function calls are either calls to predefined operators
2181 -- with static arguments, or calls to functions that rename a literal.
2182 -- Only the latter case is handled here, predefined operators are
2183 -- constant-folded elsewhere.
2185 -- If the function is itself inherited the literal of the parent type must
2186 -- be explicitly converted to the return type of the function.
2188 procedure Eval_Call
(N
: Node_Id
) is
2189 Loc
: constant Source_Ptr
:= Sloc
(N
);
2190 Typ
: constant Entity_Id
:= Etype
(N
);
2194 if Nkind
(N
) = N_Function_Call
2195 and then No
(Parameter_Associations
(N
))
2196 and then Is_Entity_Name
(Name
(N
))
2197 and then Present
(Alias
(Entity
(Name
(N
))))
2198 and then Is_Enumeration_Type
(Base_Type
(Typ
))
2200 Lit
:= Ultimate_Alias
(Entity
(Name
(N
)));
2202 if Ekind
(Lit
) = E_Enumeration_Literal
then
2203 if Base_Type
(Etype
(Lit
)) /= Base_Type
(Typ
) then
2205 (N
, Convert_To
(Typ
, New_Occurrence_Of
(Lit
, Loc
)));
2207 Rewrite
(N
, New_Occurrence_Of
(Lit
, Loc
));
2213 elsif Nkind
(N
) = N_Function_Call
2214 and then Is_Entity_Name
(Name
(N
))
2215 and then Is_Intrinsic_Subprogram
(Entity
(Name
(N
)))
2217 Eval_Intrinsic_Call
(N
, Entity
(Name
(N
)));
2219 -- Ada 2022 (AI12-0075): If checking for potentially static expressions
2220 -- is enabled and we have a call to a static function, substitute a
2221 -- static value for the call, to allow folding the expression. This
2222 -- supports checking the requirement of RM 6.8(5.3/5) in
2223 -- Analyze_Expression_Function.
2225 elsif Checking_Potentially_Static_Expression
2226 and then Is_Static_Function_Call
(N
)
2228 Fold_Dummy
(N
, Typ
);
2232 --------------------------
2233 -- Eval_Case_Expression --
2234 --------------------------
2236 -- A conditional expression is static if all its conditions and dependent
2237 -- expressions are static. Note that we do not care if the dependent
2238 -- expressions raise CE, except for the one that will be selected.
2240 procedure Eval_Case_Expression
(N
: Node_Id
) is
2245 Set_Is_Static_Expression
(N
, False);
2247 if Error_Posted
(Expression
(N
))
2248 or else not Is_Static_Expression
(Expression
(N
))
2250 Check_Non_Static_Context
(Expression
(N
));
2254 -- First loop, make sure all the alternatives are static expressions
2255 -- none of which raise Constraint_Error. We make the Constraint_Error
2256 -- check because part of the legality condition for a correct static
2257 -- case expression is that the cases are covered, like any other case
2258 -- expression. And we can't do that if any of the conditions raise an
2259 -- exception, so we don't even try to evaluate if that is the case.
2261 Alt
:= First
(Alternatives
(N
));
2262 while Present
(Alt
) loop
2264 -- The expression must be static, but we don't care at this stage
2265 -- if it raises Constraint_Error (the alternative might not match,
2266 -- in which case the expression is statically unevaluated anyway).
2268 if not Is_Static_Expression
(Expression
(Alt
)) then
2269 Check_Non_Static_Context
(Expression
(Alt
));
2273 -- The choices of a case always have to be static, and cannot raise
2274 -- an exception. If this condition is not met, then the expression
2275 -- is plain illegal, so just abandon evaluation attempts. No need
2276 -- to check non-static context when we have something illegal anyway.
2278 if not Is_OK_Static_Choice_List
(Discrete_Choices
(Alt
)) then
2285 -- OK, if the above loop gets through it means that all choices are OK
2286 -- static (don't raise exceptions), so the whole case is static, and we
2287 -- can find the matching alternative.
2289 Set_Is_Static_Expression
(N
);
2291 -- Now to deal with propagating a possible Constraint_Error
2293 -- If the selecting expression raises CE, propagate and we are done
2295 if Raises_Constraint_Error
(Expression
(N
)) then
2296 Set_Raises_Constraint_Error
(N
);
2298 -- Otherwise we need to check the alternatives to find the matching
2299 -- one. CE's in other than the matching one are not relevant. But we
2300 -- do need to check the matching one. Unlike the first loop, we do not
2301 -- have to go all the way through, when we find the matching one, quit.
2304 Alt
:= First
(Alternatives
(N
));
2307 -- We must find a match among the alternatives. If not, this must
2308 -- be due to other errors, so just ignore, leaving as non-static.
2311 Set_Is_Static_Expression
(N
, False);
2315 -- Otherwise loop through choices of this alternative
2317 Choice
:= First
(Discrete_Choices
(Alt
));
2318 while Present
(Choice
) loop
2320 -- If we find a matching choice, then the Expression of this
2321 -- alternative replaces N (Raises_Constraint_Error flag is
2322 -- included, so we don't have to special case that).
2324 if Choice_Matches
(Expression
(N
), Choice
) = Match
then
2325 Rewrite
(N
, Relocate_Node
(Expression
(Alt
)));
2335 end Eval_Case_Expression
;
2337 ------------------------
2338 -- Eval_Concatenation --
2339 ------------------------
2341 -- Concatenation is a static function, so the result is static if both
2342 -- operands are static (RM 4.9(7), 4.9(21)).
2344 procedure Eval_Concatenation
(N
: Node_Id
) is
2345 Left
: constant Node_Id
:= Left_Opnd
(N
);
2346 Right
: constant Node_Id
:= Right_Opnd
(N
);
2347 C_Typ
: constant Entity_Id
:= Root_Type
(Component_Type
(Etype
(N
)));
2352 -- Concatenation is never static in Ada 83, so if Ada 83 check operand
2353 -- non-static context.
2355 if Ada_Version
= Ada_83
2356 and then Comes_From_Source
(N
)
2358 Check_Non_Static_Context
(Left
);
2359 Check_Non_Static_Context
(Right
);
2363 -- If not foldable we are done. In principle concatenation that yields
2364 -- any string type is static (i.e. an array type of character types).
2365 -- However, character types can include enumeration literals, and
2366 -- concatenation in that case cannot be described by a literal, so we
2367 -- only consider the operation static if the result is an array of
2368 -- (a descendant of) a predefined character type.
2370 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2372 if not (Is_Standard_Character_Type
(C_Typ
) and then Fold
) then
2373 Set_Is_Static_Expression
(N
, False);
2377 -- Compile time string concatenation
2379 -- ??? Note that operands that are aggregates can be marked as static,
2380 -- so we should attempt at a later stage to fold concatenations with
2384 Left_Str
: constant Node_Id
:= Get_String_Val
(Left
);
2386 Right_Str
: constant Node_Id
:= Get_String_Val
(Right
);
2387 Folded_Val
: String_Id
:= No_String
;
2390 -- Establish new string literal, and store left operand. We make
2391 -- sure to use the special Start_String that takes an operand if
2392 -- the left operand is a string literal. Since this is optimized
2393 -- in the case where that is the most recently created string
2394 -- literal, we ensure efficient time/space behavior for the
2395 -- case of a concatenation of a series of string literals.
2397 if Nkind
(Left_Str
) = N_String_Literal
then
2398 Left_Len
:= String_Length
(Strval
(Left_Str
));
2400 -- If the left operand is the empty string, and the right operand
2401 -- is a string literal (the case of "" & "..."), the result is the
2402 -- value of the right operand. This optimization is important when
2403 -- Is_Folded_In_Parser, to avoid copying an enormous right
2406 if Left_Len
= 0 and then Nkind
(Right_Str
) = N_String_Literal
then
2407 Folded_Val
:= Strval
(Right_Str
);
2409 Start_String
(Strval
(Left_Str
));
2414 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Left_Str
)));
2418 -- Now append the characters of the right operand, unless we
2419 -- optimized the "" & "..." case above.
2421 if Nkind
(Right_Str
) = N_String_Literal
then
2422 if Left_Len
/= 0 then
2423 Store_String_Chars
(Strval
(Right_Str
));
2424 Folded_Val
:= End_String
;
2427 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Right_Str
)));
2428 Folded_Val
:= End_String
;
2431 Set_Is_Static_Expression
(N
, Stat
);
2433 -- If left operand is the empty string, the result is the
2434 -- right operand, including its bounds if anomalous.
2437 and then Is_Array_Type
(Etype
(Right
))
2438 and then Etype
(Right
) /= Any_String
2440 Set_Etype
(N
, Etype
(Right
));
2443 Fold_Str
(N
, Folded_Val
, Static
=> Stat
);
2445 end Eval_Concatenation
;
2447 ----------------------
2448 -- Eval_Entity_Name --
2449 ----------------------
2451 -- This procedure is used for identifiers and expanded names other than
2452 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
2453 -- static if they denote a static constant (RM 4.9(6)) or if the name
2454 -- denotes an enumeration literal (RM 4.9(22)).
2456 procedure Eval_Entity_Name
(N
: Node_Id
) is
2457 Def_Id
: constant Entity_Id
:= Entity
(N
);
2461 -- Enumeration literals are always considered to be constants
2462 -- and cannot raise Constraint_Error (RM 4.9(22)).
2464 if Ekind
(Def_Id
) = E_Enumeration_Literal
then
2465 Set_Is_Static_Expression
(N
);
2468 -- A name is static if it denotes a static constant (RM 4.9(5)), and
2469 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
2470 -- it does not violate 10.2.1(8) here, since this is not a variable.
2472 elsif Ekind
(Def_Id
) = E_Constant
then
2474 -- Deferred constants must always be treated as nonstatic outside the
2475 -- scope of their full view.
2477 if Present
(Full_View
(Def_Id
))
2478 and then not In_Open_Scopes
(Scope
(Def_Id
))
2482 Val
:= Constant_Value
(Def_Id
);
2485 if Present
(Val
) then
2486 Set_Is_Static_Expression
2487 (N
, Is_Static_Expression
(Val
)
2488 and then Is_Static_Subtype
(Etype
(Def_Id
)));
2489 Set_Raises_Constraint_Error
(N
, Raises_Constraint_Error
(Val
));
2491 if not Is_Static_Expression
(N
)
2492 and then not Is_Generic_Type
(Etype
(N
))
2494 Validate_Static_Object_Name
(N
);
2497 -- Mark constant condition in SCOs
2500 and then Comes_From_Source
(N
)
2501 and then Is_Boolean_Type
(Etype
(Def_Id
))
2502 and then Compile_Time_Known_Value
(N
)
2504 Set_SCO_Condition
(N
, Expr_Value_E
(N
) = Standard_True
);
2510 -- Ada 2022 (AI12-0075): If checking for potentially static expressions
2511 -- is enabled and we have a reference to a formal parameter of mode in,
2512 -- substitute a static value for the reference, to allow folding the
2513 -- expression. This supports checking the requirement of RM 6.8(5.3/5)
2514 -- in Analyze_Expression_Function.
2516 elsif Ekind
(Def_Id
) = E_In_Parameter
2517 and then Checking_Potentially_Static_Expression
2518 and then Is_Static_Function
(Scope
(Def_Id
))
2520 Fold_Dummy
(N
, Etype
(Def_Id
));
2523 -- Fall through if the name is not static
2525 Validate_Static_Object_Name
(N
);
2526 end Eval_Entity_Name
;
2528 ------------------------
2529 -- Eval_If_Expression --
2530 ------------------------
2532 -- We can fold to a static expression if the condition and both dependent
2533 -- expressions are static. Otherwise, the only required processing is to do
2534 -- the check for non-static context for the then and else expressions.
2536 procedure Eval_If_Expression
(N
: Node_Id
) is
2537 Condition
: constant Node_Id
:= First
(Expressions
(N
));
2538 Then_Expr
: constant Node_Id
:= Next
(Condition
);
2539 Else_Expr
: constant Node_Id
:= Next
(Then_Expr
);
2541 Non_Result
: Node_Id
;
2543 Rstat
: constant Boolean :=
2544 Is_Static_Expression
(Condition
)
2546 Is_Static_Expression
(Then_Expr
)
2548 Is_Static_Expression
(Else_Expr
);
2549 -- True if result is static
2552 -- If result not static, nothing to do, otherwise set static result
2557 Set_Is_Static_Expression
(N
);
2560 -- If any operand is Any_Type, just propagate to result and do not try
2561 -- to fold, this prevents cascaded errors.
2563 if Etype
(Condition
) = Any_Type
or else
2564 Etype
(Then_Expr
) = Any_Type
or else
2565 Etype
(Else_Expr
) = Any_Type
2567 Set_Etype
(N
, Any_Type
);
2568 Set_Is_Static_Expression
(N
, False);
2572 -- If condition raises Constraint_Error then we have already signaled
2573 -- an error, and we just propagate to the result and do not fold.
2575 if Raises_Constraint_Error
(Condition
) then
2576 Set_Raises_Constraint_Error
(N
);
2580 -- Static case where we can fold. Note that we don't try to fold cases
2581 -- where the condition is known at compile time, but the result is
2582 -- non-static. This avoids possible cases of infinite recursion where
2583 -- the expander puts in a redundant test and we remove it. Instead we
2584 -- deal with these cases in the expander.
2586 -- Select result operand
2588 if Is_True
(Expr_Value
(Condition
)) then
2589 Result
:= Then_Expr
;
2590 Non_Result
:= Else_Expr
;
2592 Result
:= Else_Expr
;
2593 Non_Result
:= Then_Expr
;
2596 -- Note that it does not matter if the non-result operand raises a
2597 -- Constraint_Error, but if the result raises Constraint_Error then we
2598 -- replace the node with a raise Constraint_Error. This will properly
2599 -- propagate Raises_Constraint_Error since this flag is set in Result.
2601 if Raises_Constraint_Error
(Result
) then
2602 Rewrite_In_Raise_CE
(N
, Result
);
2603 Check_Non_Static_Context
(Non_Result
);
2605 -- Otherwise the result operand replaces the original node
2608 Rewrite
(N
, Relocate_Node
(Result
));
2609 Set_Is_Static_Expression
(N
);
2611 end Eval_If_Expression
;
2613 ----------------------------
2614 -- Eval_Indexed_Component --
2615 ----------------------------
2617 -- Indexed components are never static, so we need to perform the check
2618 -- for non-static context on the index values. Then, we check if the
2619 -- value can be obtained at compile time, even though it is non-static.
2621 procedure Eval_Indexed_Component
(N
: Node_Id
) is
2625 -- Check for non-static context on index values
2627 Expr
:= First
(Expressions
(N
));
2628 while Present
(Expr
) loop
2629 Check_Non_Static_Context
(Expr
);
2633 -- If the indexed component appears in an object renaming declaration
2634 -- then we do not want to try to evaluate it, since in this case we
2635 -- need the identity of the array element.
2637 if Nkind
(Parent
(N
)) = N_Object_Renaming_Declaration
then
2640 -- Similarly if the indexed component appears as the prefix of an
2641 -- attribute we don't want to evaluate it, because at least for
2642 -- some cases of attributes we need the identify (e.g. Access, Size).
2644 elsif Nkind
(Parent
(N
)) = N_Attribute_Reference
then
2648 -- Note: there are other cases, such as the left side of an assignment,
2649 -- or an OUT parameter for a call, where the replacement results in the
2650 -- illegal use of a constant, But these cases are illegal in the first
2651 -- place, so the replacement, though silly, is harmless.
2653 -- Now see if this is a constant array reference
2655 if List_Length
(Expressions
(N
)) = 1
2656 and then Is_Entity_Name
(Prefix
(N
))
2657 and then Ekind
(Entity
(Prefix
(N
))) = E_Constant
2658 and then Present
(Constant_Value
(Entity
(Prefix
(N
))))
2661 Loc
: constant Source_Ptr
:= Sloc
(N
);
2662 Arr
: constant Node_Id
:= Constant_Value
(Entity
(Prefix
(N
)));
2663 Sub
: constant Node_Id
:= First
(Expressions
(N
));
2669 -- Linear one's origin subscript value for array reference
2672 -- Lower bound of the first array index
2675 -- Value from constant array
2678 Atyp
:= Etype
(Arr
);
2680 if Is_Access_Type
(Atyp
) then
2681 Atyp
:= Designated_Type
(Atyp
);
2684 -- If we have an array type (we should have but perhaps there are
2685 -- error cases where this is not the case), then see if we can do
2686 -- a constant evaluation of the array reference.
2688 if Is_Array_Type
(Atyp
) and then Atyp
/= Any_Composite
then
2689 if Ekind
(Atyp
) = E_String_Literal_Subtype
then
2690 Lbd
:= String_Literal_Low_Bound
(Atyp
);
2692 Lbd
:= Type_Low_Bound
(Etype
(First_Index
(Atyp
)));
2695 if Compile_Time_Known_Value
(Sub
)
2696 and then Nkind
(Arr
) = N_Aggregate
2697 and then Compile_Time_Known_Value
(Lbd
)
2698 and then Is_Discrete_Type
(Component_Type
(Atyp
))
2700 Lin
:= UI_To_Int
(Expr_Value
(Sub
) - Expr_Value
(Lbd
)) + 1;
2702 if List_Length
(Expressions
(Arr
)) >= Lin
then
2703 Elm
:= Pick
(Expressions
(Arr
), Lin
);
2705 -- If the resulting expression is compile-time-known,
2706 -- then we can rewrite the indexed component with this
2707 -- value, being sure to mark the result as non-static.
2708 -- We also reset the Sloc, in case this generates an
2709 -- error later on (e.g. 136'Access).
2711 if Compile_Time_Known_Value
(Elm
) then
2712 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2713 Set_Is_Static_Expression
(N
, False);
2718 -- We can also constant-fold if the prefix is a string literal.
2719 -- This will be useful in an instantiation or an inlining.
2721 elsif Compile_Time_Known_Value
(Sub
)
2722 and then Nkind
(Arr
) = N_String_Literal
2723 and then Compile_Time_Known_Value
(Lbd
)
2724 and then Expr_Value
(Lbd
) = 1
2725 and then Expr_Value
(Sub
) <=
2726 String_Literal_Length
(Etype
(Arr
))
2729 C
: constant Char_Code
:=
2730 Get_String_Char
(Strval
(Arr
),
2731 UI_To_Int
(Expr_Value
(Sub
)));
2733 Set_Character_Literal_Name
(C
);
2736 Make_Character_Literal
(Loc
,
2738 Char_Literal_Value
=> UI_From_CC
(C
));
2739 Set_Etype
(Elm
, Component_Type
(Atyp
));
2740 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2741 Set_Is_Static_Expression
(N
, False);
2747 end Eval_Indexed_Component
;
2749 --------------------------
2750 -- Eval_Integer_Literal --
2751 --------------------------
2753 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2754 -- as static by the analyzer. The reason we did it that early is to allow
2755 -- the possibility of turning off the Is_Static_Expression flag after
2756 -- analysis, but before resolution, when integer literals are generated in
2757 -- the expander that do not correspond to static expressions.
2759 procedure Eval_Integer_Literal
(N
: Node_Id
) is
2760 function In_Any_Integer_Context
(K
: Node_Kind
) return Boolean;
2761 -- If the literal is resolved with a specific type in a context where
2762 -- the expected type is Any_Integer, there are no range checks on the
2763 -- literal. By the time the literal is evaluated, it carries the type
2764 -- imposed by the enclosing expression, and we must recover the context
2765 -- to determine that Any_Integer is meant.
2767 ----------------------------
2768 -- In_Any_Integer_Context --
2769 ----------------------------
2771 function In_Any_Integer_Context
(K
: Node_Kind
) return Boolean is
2773 -- Any_Integer also appears in digits specifications for real types,
2774 -- but those have bounds smaller that those of any integer base type,
2775 -- so we can safely ignore these cases.
2777 return K
in N_Attribute_Definition_Clause
2778 | N_Modular_Type_Definition
2779 | N_Number_Declaration
2780 | N_Signed_Integer_Type_Definition
;
2781 end In_Any_Integer_Context
;
2785 PK
: constant Node_Kind
:= Nkind
(Parent
(N
));
2786 Typ
: constant Entity_Id
:= Etype
(N
);
2788 -- Start of processing for Eval_Integer_Literal
2791 -- If the literal appears in a non-expression context, then it is
2792 -- certainly appearing in a non-static context, so check it. This is
2793 -- actually a redundant check, since Check_Non_Static_Context would
2794 -- check it, but it seems worthwhile to optimize out the call.
2796 -- Additionally, when the literal appears within an if or case
2797 -- expression it must be checked as well. However, due to the literal
2798 -- appearing within a conditional statement, expansion greatly changes
2799 -- the nature of its context and performing some of the checks within
2800 -- Check_Non_Static_Context on an expanded literal may lead to spurious
2801 -- and misleading warnings.
2803 if (PK
not in N_Case_Expression_Alternative | N_Subexpr
2804 or else (PK
in N_Case_Expression_Alternative | N_If_Expression
2806 Comes_From_Source
(N
)))
2807 and then not In_Any_Integer_Context
(PK
)
2809 Check_Non_Static_Context
(N
);
2812 -- Modular integer literals must be in their base range
2814 if Is_Modular_Integer_Type
(Typ
)
2815 and then Is_Out_Of_Range
(N
, Base_Type
(Typ
), Assume_Valid
=> True)
2819 end Eval_Integer_Literal
;
2821 -------------------------
2822 -- Eval_Intrinsic_Call --
2823 -------------------------
2825 procedure Eval_Intrinsic_Call
(N
: Node_Id
; E
: Entity_Id
) is
2827 procedure Eval_Shift
(N
: Node_Id
; E
: Entity_Id
; Op
: Node_Kind
);
2828 -- Evaluate an intrinsic shift call N on the given subprogram E.
2829 -- Op is the kind for the shift node.
2835 procedure Eval_Shift
(N
: Node_Id
; E
: Entity_Id
; Op
: Node_Kind
) is
2836 Left
: constant Node_Id
:= First_Actual
(N
);
2837 Right
: constant Node_Id
:= Next_Actual
(Left
);
2838 Static
: constant Boolean := Is_Static_Function
(E
);
2842 if Checking_Potentially_Static_Expression
then
2843 Fold_Dummy
(N
, Etype
(N
));
2849 (N
, Left
, Right
, Op
, Static
=> Static
, Check_Elab
=> not Static
);
2855 -- Nothing to do if the intrinsic is handled by the back end.
2857 if Present
(Interface_Name
(E
)) then
2861 -- Intrinsic calls as part of a static function is a (core)
2862 -- language extension.
2864 if Checking_Potentially_Static_Expression
2865 and then not Core_Extensions_Allowed
2870 -- If we have a renaming, expand the call to the original operation,
2871 -- which must itself be intrinsic, since renaming requires matching
2872 -- conventions and this has already been checked.
2874 if Present
(Alias
(E
)) then
2875 Eval_Intrinsic_Call
(N
, Alias
(E
));
2879 -- If the intrinsic subprogram is generic, gets its original name
2881 if Present
(Parent
(E
))
2882 and then Present
(Generic_Parent
(Parent
(E
)))
2884 Nam
:= Chars
(Generic_Parent
(Parent
(E
)));
2890 when Name_Shift_Left
=>
2891 Eval_Shift
(N
, E
, N_Op_Shift_Left
);
2892 when Name_Shift_Right
=>
2893 Eval_Shift
(N
, E
, N_Op_Shift_Right
);
2894 when Name_Shift_Right_Arithmetic
=>
2895 Eval_Shift
(N
, E
, N_Op_Shift_Right_Arithmetic
);
2899 end Eval_Intrinsic_Call
;
2901 ---------------------
2902 -- Eval_Logical_Op --
2903 ---------------------
2905 -- Logical operations are static functions, so the result is potentially
2906 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2908 procedure Eval_Logical_Op
(N
: Node_Id
) is
2909 Left
: constant Node_Id
:= Left_Opnd
(N
);
2910 Right
: constant Node_Id
:= Right_Opnd
(N
);
2911 Left_Int
: Uint
:= No_Uint
;
2912 Right_Int
: Uint
:= No_Uint
;
2917 -- If not foldable we are done
2919 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2925 -- Compile time evaluation of logical operation
2927 if Is_Modular_Integer_Type
(Etype
(N
)) then
2928 Left_Int
:= Expr_Value
(Left
);
2929 Right_Int
:= Expr_Value
(Right
);
2932 Left_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2933 Right_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2936 To_Bits
(Left_Int
, Left_Bits
);
2937 To_Bits
(Right_Int
, Right_Bits
);
2939 -- Note: should really be able to use array ops instead of
2940 -- these loops, but they break the build with a cryptic error
2941 -- during the bind of gnat1 likely due to a wrong computation
2942 -- of a date or checksum.
2944 if Nkind
(N
) = N_Op_And
then
2945 for J
in Left_Bits
'Range loop
2946 Left_Bits
(J
) := Left_Bits
(J
) and Right_Bits
(J
);
2949 elsif Nkind
(N
) = N_Op_Or
then
2950 for J
in Left_Bits
'Range loop
2951 Left_Bits
(J
) := Left_Bits
(J
) or Right_Bits
(J
);
2955 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2957 for J
in Left_Bits
'Range loop
2958 Left_Bits
(J
) := Left_Bits
(J
) xor Right_Bits
(J
);
2962 Fold_Uint
(N
, From_Bits
(Left_Bits
, Etype
(N
)), Stat
);
2966 pragma Assert
(Is_Boolean_Type
(Etype
(N
)));
2968 if Compile_Time_Known_Value
(Left
)
2969 and then Compile_Time_Known_Value
(Right
)
2971 Right_Int
:= Expr_Value
(Right
);
2972 Left_Int
:= Expr_Value
(Left
);
2975 if Nkind
(N
) = N_Op_And
then
2977 -- If Left or Right are not compile time known values it means
2978 -- that the result is always False as per
2979 -- Test_Expression_Is_Foldable.
2980 -- Note that in this case, both Right_Int and Left_Int are set
2981 -- to No_Uint, so need to test for both.
2983 if No
(Right_Int
) then
2984 Fold_Uint
(N
, Uint_0
, Stat
);
2987 Test
(Is_True
(Left_Int
) and then Is_True
(Right_Int
)), Stat
);
2989 elsif Nkind
(N
) = N_Op_Or
then
2991 -- If Left or Right are not compile time known values it means
2992 -- that the result is always True. as per
2993 -- Test_Expression_Is_Foldable.
2994 -- Note that in this case, both Right_Int and Left_Int are set
2995 -- to No_Uint, so need to test for both.
2997 if No
(Right_Int
) then
2998 Fold_Uint
(N
, Uint_1
, Stat
);
3001 Test
(Is_True
(Left_Int
) or else Is_True
(Right_Int
)), Stat
);
3004 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
3006 Test
(Is_True
(Left_Int
) xor Is_True
(Right_Int
)), Stat
);
3009 end Eval_Logical_Op
;
3011 ------------------------
3012 -- Eval_Membership_Op --
3013 ------------------------
3015 -- A membership test is potentially static if the expression is static, and
3016 -- the range is a potentially static range, or is a subtype mark denoting a
3017 -- static subtype (RM 4.9(12)).
3019 procedure Eval_Membership_Op
(N
: Node_Id
) is
3020 Alts
: constant List_Id
:= Alternatives
(N
);
3021 Choice
: constant Node_Id
:= Right_Opnd
(N
);
3022 Expr
: constant Node_Id
:= Left_Opnd
(N
);
3023 Result
: Match_Result
;
3026 -- Ignore if error in either operand, except to make sure that Any_Type
3027 -- is properly propagated to avoid junk cascaded errors.
3029 if Etype
(Expr
) = Any_Type
3030 or else (Present
(Choice
) and then Etype
(Choice
) = Any_Type
)
3032 Set_Etype
(N
, Any_Type
);
3036 -- If left operand non-static, then nothing to do
3038 if not Is_Static_Expression
(Expr
) then
3042 -- If choice is non-static, left operand is in non-static context
3044 if (Present
(Choice
) and then not Is_Static_Choice
(Choice
))
3045 or else (Present
(Alts
) and then not Is_Static_Choice_List
(Alts
))
3047 Check_Non_Static_Context
(Expr
);
3051 -- Otherwise we definitely have a static expression
3053 Set_Is_Static_Expression
(N
);
3055 -- If left operand raises Constraint_Error, propagate and we are done
3057 if Raises_Constraint_Error
(Expr
) then
3058 Set_Raises_Constraint_Error
(N
, True);
3063 if Present
(Choice
) then
3064 Result
:= Choice_Matches
(Expr
, Choice
);
3066 Result
:= Choices_Match
(Expr
, Alts
);
3069 -- If result is Non_Static, it means that we raise Constraint_Error,
3070 -- since we already tested that the operands were themselves static.
3072 if Result
= Non_Static
then
3073 Set_Raises_Constraint_Error
(N
);
3075 -- Otherwise we have our result (flipped if NOT IN case)
3079 (N
, Test
(Result
= Match
xor Nkind
(N
) = N_Not_In
), True);
3080 Warn_On_Known_Condition
(N
);
3083 end Eval_Membership_Op
;
3085 ------------------------
3086 -- Eval_Named_Integer --
3087 ------------------------
3089 procedure Eval_Named_Integer
(N
: Node_Id
) is
3092 Expr_Value
(Expression
(Declaration_Node
(Entity
(N
)))), True);
3093 end Eval_Named_Integer
;
3095 ---------------------
3096 -- Eval_Named_Real --
3097 ---------------------
3099 procedure Eval_Named_Real
(N
: Node_Id
) is
3102 Expr_Value_R
(Expression
(Declaration_Node
(Entity
(N
)))), True);
3103 end Eval_Named_Real
;
3109 -- Exponentiation is a static functions, so the result is potentially
3110 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
3112 procedure Eval_Op_Expon
(N
: Node_Id
) is
3113 Left
: constant Node_Id
:= Left_Opnd
(N
);
3114 Right
: constant Node_Id
:= Right_Opnd
(N
);
3119 -- If not foldable we are done
3121 Test_Expression_Is_Foldable
3122 (N
, Left
, Right
, Stat
, Fold
, CRT_Safe
=> True);
3124 -- Return if not foldable
3130 if Configurable_Run_Time_Mode
and not Stat
then
3134 -- Fold exponentiation operation
3137 Right_Int
: constant Uint
:= Expr_Value
(Right
);
3142 if Is_Integer_Type
(Etype
(Left
)) then
3144 Left_Int
: constant Uint
:= Expr_Value
(Left
);
3148 -- Exponentiation of an integer raises Constraint_Error for a
3149 -- negative exponent (RM 4.5.6).
3151 if Right_Int
< 0 then
3152 Apply_Compile_Time_Constraint_Error
3153 (N
, "integer exponent negative", CE_Range_Check_Failed
,
3158 if OK_Bits
(N
, Num_Bits
(Left_Int
) * Right_Int
) then
3159 Result
:= Left_Int
** Right_Int
;
3164 if Is_Modular_Integer_Type
(Etype
(N
)) then
3165 Result
:= Result
mod Modulus
(Etype
(N
));
3168 Check_Non_Static_Context_For_Overflow
(N
, Stat
, Result
);
3170 Fold_Uint
(N
, Result
, Stat
);
3178 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
3181 -- Cannot have a zero base with a negative exponent
3183 if UR_Is_Zero
(Left_Real
) then
3185 if Right_Int
< 0 then
3186 Apply_Compile_Time_Constraint_Error
3187 (N
, "zero ** negative integer", CE_Range_Check_Failed
,
3191 Fold_Ureal
(N
, Ureal_0
, Stat
);
3195 Fold_Ureal
(N
, Left_Real
** Right_Int
, Stat
);
3206 -- The not operation is a static function, so the result is potentially
3207 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
3209 procedure Eval_Op_Not
(N
: Node_Id
) is
3210 Right
: constant Node_Id
:= Right_Opnd
(N
);
3215 -- If not foldable we are done
3217 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
3223 -- Fold not operation
3226 Rint
: constant Uint
:= Expr_Value
(Right
);
3227 Typ
: constant Entity_Id
:= Etype
(N
);
3230 -- Negation is equivalent to subtracting from the modulus minus one.
3231 -- For a binary modulus this is equivalent to the ones-complement of
3232 -- the original value. For a nonbinary modulus this is an arbitrary
3233 -- but consistent definition.
3235 if Is_Modular_Integer_Type
(Typ
) then
3236 Fold_Uint
(N
, Modulus
(Typ
) - 1 - Rint
, Stat
);
3237 else pragma Assert
(Is_Boolean_Type
(Typ
));
3238 Fold_Uint
(N
, Test
(not Is_True
(Rint
)), Stat
);
3241 Set_Is_Static_Expression
(N
, Stat
);
3245 -------------------------------
3246 -- Eval_Qualified_Expression --
3247 -------------------------------
3249 -- A qualified expression is potentially static if its subtype mark denotes
3250 -- a static subtype and its expression is potentially static (RM 4.9 (10)).
3252 procedure Eval_Qualified_Expression
(N
: Node_Id
) is
3253 Operand
: constant Node_Id
:= Expression
(N
);
3254 Target_Type
: constant Entity_Id
:= Entity
(Subtype_Mark
(N
));
3261 -- Can only fold if target is string or scalar and subtype is static.
3262 -- Also, do not fold if our parent is an allocator (this is because the
3263 -- qualified expression is really part of the syntactic structure of an
3264 -- allocator, and we do not want to end up with something that
3265 -- corresponds to "new 1" where the 1 is the result of folding a
3266 -- qualified expression).
3268 if not Is_Static_Subtype
(Target_Type
)
3269 or else Nkind
(Parent
(N
)) = N_Allocator
3271 Check_Non_Static_Context
(Operand
);
3273 -- If operand is known to raise Constraint_Error, set the flag on the
3274 -- expression so it does not get optimized away.
3276 if Nkind
(Operand
) = N_Raise_Constraint_Error
then
3277 Set_Raises_Constraint_Error
(N
);
3282 -- Also return if a semantic error has been posted on the node, as we
3283 -- don't want to fold in that case (for GNATprove, the node might lead
3284 -- to Constraint_Error but won't have been replaced with a raise node
3285 -- or marked as raising CE).
3287 elsif Error_Posted
(N
) then
3291 -- If not foldable we are done
3293 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
3298 -- Don't try fold if target type has Constraint_Error bounds
3300 elsif not Is_OK_Static_Subtype
(Target_Type
) then
3301 Set_Raises_Constraint_Error
(N
);
3305 -- Fold the result of qualification
3307 if Is_Discrete_Type
(Target_Type
) then
3309 -- Save Print_In_Hex indication
3311 Hex
:= Nkind
(Operand
) = N_Integer_Literal
3312 and then Print_In_Hex
(Operand
);
3314 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
3316 -- Preserve Print_In_Hex indication
3318 if Hex
and then Nkind
(N
) = N_Integer_Literal
then
3319 Set_Print_In_Hex
(N
);
3322 elsif Is_Real_Type
(Target_Type
) then
3323 Fold_Ureal
(N
, Expr_Value_R
(Operand
), Stat
);
3326 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Stat
);
3329 Set_Is_Static_Expression
(N
, False);
3331 Check_String_Literal_Length
(N
, Target_Type
);
3337 -- The expression may be foldable but not static
3339 Set_Is_Static_Expression
(N
, Stat
);
3341 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
3344 end Eval_Qualified_Expression
;
3346 -----------------------
3347 -- Eval_Real_Literal --
3348 -----------------------
3350 -- Numeric literals are static (RM 4.9(1)), and have already been marked
3351 -- as static by the analyzer. The reason we did it that early is to allow
3352 -- the possibility of turning off the Is_Static_Expression flag after
3353 -- analysis, but before resolution, when integer literals are generated
3354 -- in the expander that do not correspond to static expressions.
3356 procedure Eval_Real_Literal
(N
: Node_Id
) is
3357 PK
: constant Node_Kind
:= Nkind
(Parent
(N
));
3360 -- If the literal appears in a non-expression context and not as part of
3361 -- a number declaration, then it is appearing in a non-static context,
3364 if PK
not in N_Subexpr
and then PK
/= N_Number_Declaration
then
3365 Check_Non_Static_Context
(N
);
3367 end Eval_Real_Literal
;
3369 ------------------------
3370 -- Eval_Relational_Op --
3371 ------------------------
3373 -- Relational operations are static functions, so the result is static if
3374 -- both operands are static (RM 4.9(7), 4.9(20)), except that up to Ada
3375 -- 2012, for strings the result is never static, even if the operands are.
3376 -- The string case was relaxed in Ada 2022, see AI12-0201.
3378 -- However, for internally generated nodes, we allow string equality and
3379 -- inequality to be static. This is because we rewrite A in "ABC" as an
3380 -- equality test A = "ABC", and the former is definitely static.
3382 procedure Eval_Relational_Op
(N
: Node_Id
) is
3383 Left
: constant Node_Id
:= Left_Opnd
(N
);
3384 Right
: constant Node_Id
:= Right_Opnd
(N
);
3386 procedure Decompose_Expr
3388 Ent
: out Entity_Id
;
3389 Kind
: out Character;
3391 Orig
: Boolean := True);
3392 -- Given expression Expr, see if it is of the form X [+/- K]. If so, Ent
3393 -- is set to the entity in X, Kind is 'F','L','E' for 'First or 'Last or
3394 -- simple entity, and Cons is the value of K. If the expression is not
3395 -- of the required form, Ent is set to Empty.
3397 -- Orig indicates whether Expr is the original expression to consider,
3398 -- or if we are handling a subexpression (e.g. recursive call to
3401 procedure Fold_General_Op
(Is_Static
: Boolean);
3402 -- Attempt to fold arbitrary relational operator N. Flag Is_Static must
3403 -- be set when the operator denotes a static expression.
3405 procedure Fold_Static_Real_Op
;
3406 -- Attempt to fold static real type relational operator N
3408 function Static_Length
(Expr
: Node_Id
) return Uint
;
3409 -- If Expr is an expression for a constrained array whose length is
3410 -- known at compile time, return the non-negative length, otherwise
3413 --------------------
3414 -- Decompose_Expr --
3415 --------------------
3417 procedure Decompose_Expr
3419 Ent
: out Entity_Id
;
3420 Kind
: out Character;
3422 Orig
: Boolean := True)
3427 -- Assume that the expression does not meet the expected form
3433 if Nkind
(Expr
) = N_Op_Add
3434 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
3436 Exp
:= Left_Opnd
(Expr
);
3437 Cons
:= Expr_Value
(Right_Opnd
(Expr
));
3439 elsif Nkind
(Expr
) = N_Op_Subtract
3440 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
3442 Exp
:= Left_Opnd
(Expr
);
3443 Cons
:= -Expr_Value
(Right_Opnd
(Expr
));
3445 -- If the bound is a constant created to remove side effects, recover
3446 -- the original expression to see if it has one of the recognizable
3449 elsif Nkind
(Expr
) = N_Identifier
3450 and then not Comes_From_Source
(Entity
(Expr
))
3451 and then Ekind
(Entity
(Expr
)) = E_Constant
3452 and then Nkind
(Parent
(Entity
(Expr
))) = N_Object_Declaration
3454 Exp
:= Expression
(Parent
(Entity
(Expr
)));
3455 Decompose_Expr
(Exp
, Ent
, Kind
, Cons
, Orig
=> False);
3457 -- If original expression includes an entity, create a reference
3458 -- to it for use below.
3460 if Present
(Ent
) then
3461 Exp
:= New_Occurrence_Of
(Ent
, Sloc
(Ent
));
3467 -- Only consider the case of X + 0 for a full expression, and
3468 -- not when recursing, otherwise we may end up with evaluating
3469 -- expressions not known at compile time to 0.
3479 -- At this stage Exp is set to the potential X
3481 if Nkind
(Exp
) = N_Attribute_Reference
then
3482 if Attribute_Name
(Exp
) = Name_First
then
3484 elsif Attribute_Name
(Exp
) = Name_Last
then
3490 Exp
:= Prefix
(Exp
);
3496 if Is_Entity_Name
(Exp
) and then Present
(Entity
(Exp
)) then
3497 Ent
:= Entity
(Exp
);
3501 ---------------------
3502 -- Fold_General_Op --
3503 ---------------------
3505 procedure Fold_General_Op
(Is_Static
: Boolean) is
3506 CR
: constant Compare_Result
:=
3507 Compile_Time_Compare
(Left
, Right
, Assume_Valid
=> False);
3512 if CR
= Unknown
then
3520 elsif CR
= NE
or else CR
= GT
or else CR
= LT
then
3527 if CR
= GT
or else CR
= EQ
or else CR
= GE
then
3538 elsif CR
= EQ
or else CR
= LT
or else CR
= LE
then
3545 if CR
= LT
or else CR
= EQ
or else CR
= LE
then
3556 elsif CR
= EQ
or else CR
= GT
or else CR
= GE
then
3563 if CR
= NE
or else CR
= GT
or else CR
= LT
then
3572 raise Program_Error
;
3575 -- Determine the potential outcome of the relation assuming the
3576 -- operands are valid and emit a warning when the relation yields
3577 -- True or False only in the presence of invalid values.
3579 Warn_On_Constant_Valid_Condition
(N
);
3581 Fold_Uint
(N
, Test
(Result
), Is_Static
);
3582 end Fold_General_Op
;
3584 -------------------------
3585 -- Fold_Static_Real_Op --
3586 -------------------------
3588 procedure Fold_Static_Real_Op
is
3589 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
3590 Right_Real
: constant Ureal
:= Expr_Value_R
(Right
);
3595 when N_Op_Eq
=> Result
:= (Left_Real
= Right_Real
);
3596 when N_Op_Ge
=> Result
:= (Left_Real
>= Right_Real
);
3597 when N_Op_Gt
=> Result
:= (Left_Real
> Right_Real
);
3598 when N_Op_Le
=> Result
:= (Left_Real
<= Right_Real
);
3599 when N_Op_Lt
=> Result
:= (Left_Real
< Right_Real
);
3600 when N_Op_Ne
=> Result
:= (Left_Real
/= Right_Real
);
3601 when others => raise Program_Error
;
3604 Fold_Uint
(N
, Test
(Result
), True);
3605 end Fold_Static_Real_Op
;
3611 function Static_Length
(Expr
: Node_Id
) return Uint
is
3621 -- First easy case string literal
3623 if Nkind
(Expr
) = N_String_Literal
then
3624 return UI_From_Int
(String_Length
(Strval
(Expr
)));
3626 -- With frontend inlining as performed in GNATprove mode, a variable
3627 -- may be inserted that has a string literal subtype. Deal with this
3628 -- specially as for the previous case.
3630 elsif Ekind
(Etype
(Expr
)) = E_String_Literal_Subtype
then
3631 return String_Literal_Length
(Etype
(Expr
));
3633 -- Second easy case, not constrained subtype, so no length
3635 elsif not Is_Constrained
(Etype
(Expr
)) then
3636 return Uint_Minus_1
;
3641 Typ
:= Etype
(First_Index
(Etype
(Expr
)));
3643 -- The simple case, both bounds are known at compile time
3645 if Is_Discrete_Type
(Typ
)
3646 and then Compile_Time_Known_Value
(Type_Low_Bound
(Typ
))
3647 and then Compile_Time_Known_Value
(Type_High_Bound
(Typ
))
3650 UI_Max
(Uint_0
, Expr_Value
(Type_High_Bound
(Typ
)) -
3651 Expr_Value
(Type_Low_Bound
(Typ
)) + 1);
3654 -- A more complex case, where the bounds are of the form X [+/- K1]
3655 -- .. X [+/- K2]), where X is an expression that is either A'First or
3656 -- A'Last (with A an entity name), or X is an entity name, and the
3657 -- two X's are the same and K1 and K2 are known at compile time, in
3658 -- this case, the length can also be computed at compile time, even
3659 -- though the bounds are not known. A common case of this is e.g.
3660 -- (X'First .. X'First+5).
3663 (Original_Node
(Type_Low_Bound
(Typ
)), Ent1
, Kind1
, Cons1
);
3665 (Original_Node
(Type_High_Bound
(Typ
)), Ent2
, Kind2
, Cons2
);
3667 if Present
(Ent1
) and then Ent1
= Ent2
and then Kind1
= Kind2
then
3668 return Cons2
- Cons1
+ 1;
3670 return Uint_Minus_1
;
3676 Left_Typ
: constant Entity_Id
:= Etype
(Left
);
3677 Right_Typ
: constant Entity_Id
:= Etype
(Right
);
3680 Op_Typ
: Entity_Id
:= Empty
;
3683 Is_Static_Expression
: Boolean;
3685 -- Start of processing for Eval_Relational_Op
3688 -- One special case to deal with first. If we can tell that the result
3689 -- will be false because the lengths of one or more index subtypes are
3690 -- compile-time known and different, then we can replace the entire
3691 -- result by False. We only do this for one-dimensional arrays, because
3692 -- the case of multidimensional arrays is rare and too much trouble. If
3693 -- one of the operands is an illegal aggregate, its type might still be
3694 -- an arbitrary composite type, so nothing to do.
3696 if Is_Array_Type
(Left_Typ
)
3697 and then Left_Typ
/= Any_Composite
3698 and then Number_Dimensions
(Left_Typ
) = 1
3699 and then Nkind
(N
) in N_Op_Eq | N_Op_Ne
3701 if Raises_Constraint_Error
(Left
)
3703 Raises_Constraint_Error
(Right
)
3708 -- OK, we have the case where we may be able to do this fold
3710 Left_Len
:= Static_Length
(Left
);
3711 Right_Len
:= Static_Length
(Right
);
3713 if Left_Len
/= Uint_Minus_1
3714 and then Right_Len
/= Uint_Minus_1
3715 and then Left_Len
/= Right_Len
3717 -- AI12-0201: comparison of string is static in Ada 2022
3721 Test
(Nkind
(N
) = N_Op_Ne
),
3722 Static
=> Ada_Version
>= Ada_2022
3723 and then Is_String_Type
(Left_Typ
));
3724 Warn_On_Known_Condition
(N
);
3731 -- Initialize the value of Is_Static_Expression. The value of Fold
3732 -- returned by Test_Expression_Is_Foldable is not needed since, even
3733 -- when some operand is a variable, we can still perform the static
3734 -- evaluation of the expression in some cases (for example, for a
3735 -- variable of a subtype of Integer we statically know that any value
3736 -- stored in such variable is smaller than Integer'Last).
3738 Test_Expression_Is_Foldable
3739 (N
, Left
, Right
, Is_Static_Expression
, Fold
);
3741 -- Comparisons of scalars can give static results.
3742 -- In addition starting with Ada 2022 (AI12-0201), comparison of strings
3743 -- can also give static results, and as noted above, we also allow for
3744 -- earlier Ada versions internally generated equality and inequality for
3746 -- The Comes_From_Source test below isn't correct and will accept
3747 -- some cases that are illegal in Ada 2012 and before. Now that Ada
3748 -- 2022 has relaxed the rules, this doesn't really matter.
3750 if Is_String_Type
(Left_Typ
) then
3751 if Ada_Version
< Ada_2022
3752 and then (Comes_From_Source
(N
)
3753 or else Nkind
(N
) not in N_Op_Eq | N_Op_Ne
)
3755 Is_Static_Expression
:= False;
3756 Set_Is_Static_Expression
(N
, False);
3759 elsif not Is_Scalar_Type
(Left_Typ
) then
3760 Is_Static_Expression
:= False;
3761 Set_Is_Static_Expression
(N
, False);
3764 -- For operators on universal numeric types called as functions with an
3765 -- explicit scope, determine appropriate specific numeric type, and
3766 -- diagnose possible ambiguity.
3768 if Is_Universal_Numeric_Type
(Left_Typ
)
3770 Is_Universal_Numeric_Type
(Right_Typ
)
3772 Op_Typ
:= Find_Universal_Operator_Type
(N
);
3775 -- Attempt to fold the relational operator
3777 if Is_Static_Expression
and then Is_Real_Type
(Left_Typ
) then
3778 Fold_Static_Real_Op
;
3780 Fold_General_Op
(Is_Static_Expression
);
3783 -- For the case of a folded relational operator on a specific numeric
3784 -- type, freeze the operand type now.
3786 if Present
(Op_Typ
) then
3787 Freeze_Before
(N
, Op_Typ
);
3790 Warn_On_Known_Condition
(N
);
3791 end Eval_Relational_Op
;
3793 -----------------------------
3794 -- Eval_Selected_Component --
3795 -----------------------------
3797 procedure Eval_Selected_Component
(N
: Node_Id
) is
3804 -- If an attribute reference or a LHS, nothing to do.
3805 -- Also do not fold if N is an [in] out subprogram parameter.
3806 -- Fold will perform the other relevant tests.
3808 if Nkind
(Parent
(N
)) /= N_Attribute_Reference
3809 and then not Known_To_Be_Assigned
(N
)
3810 and then not Is_Actual_Out_Or_In_Out_Parameter
(N
)
3812 -- Simplify a selected_component on an aggregate by extracting
3813 -- the field directly.
3815 Node
:= Unqualify
(Prefix
(N
));
3817 if Nkind
(Node
) = N_Aggregate
3818 and then Compile_Time_Known_Aggregate
(Node
)
3820 Comp
:= First
(Component_Associations
(Node
));
3821 Nam
:= Chars
(Selector_Name
(N
));
3823 while Present
(Comp
) loop
3824 C
:= First
(Choices
(Comp
));
3826 while Present
(C
) loop
3827 if Chars
(C
) = Nam
then
3828 Rewrite
(N
, Relocate_Node
(Expression
(Comp
)));
3841 end Eval_Selected_Component
;
3847 procedure Eval_Shift
(N
: Node_Id
) is
3849 -- This procedure is only called for compiler generated code (e.g.
3850 -- packed arrays), so there is nothing to do except attempting to fold
3853 Fold_Shift
(N
, Left_Opnd
(N
), Right_Opnd
(N
), Nkind
(N
));
3856 ------------------------
3857 -- Eval_Short_Circuit --
3858 ------------------------
3860 -- A short circuit operation is potentially static if both operands are
3861 -- potentially static (RM 4.9 (13)).
3863 procedure Eval_Short_Circuit
(N
: Node_Id
) is
3864 Kind
: constant Node_Kind
:= Nkind
(N
);
3865 Left
: constant Node_Id
:= Left_Opnd
(N
);
3866 Right
: constant Node_Id
:= Right_Opnd
(N
);
3869 Rstat
: constant Boolean :=
3870 Is_Static_Expression
(Left
)
3872 Is_Static_Expression
(Right
);
3875 -- Short circuit operations are never static in Ada 83
3877 if Ada_Version
= Ada_83
and then Comes_From_Source
(N
) then
3878 Check_Non_Static_Context
(Left
);
3879 Check_Non_Static_Context
(Right
);
3883 -- Now look at the operands, we can't quite use the normal call to
3884 -- Test_Expression_Is_Foldable here because short circuit operations
3885 -- are a special case, they can still be foldable, even if the right
3886 -- operand raises Constraint_Error.
3888 -- If either operand is Any_Type, just propagate to result and do not
3889 -- try to fold, this prevents cascaded errors.
3891 if Etype
(Left
) = Any_Type
or else Etype
(Right
) = Any_Type
then
3892 Set_Etype
(N
, Any_Type
);
3895 -- If left operand raises Constraint_Error, then replace node N with
3896 -- the raise Constraint_Error node, and we are obviously not foldable.
3897 -- Is_Static_Expression is set from the two operands in the normal way,
3898 -- and we check the right operand if it is in a non-static context.
3900 elsif Raises_Constraint_Error
(Left
) then
3902 Check_Non_Static_Context
(Right
);
3905 Rewrite_In_Raise_CE
(N
, Left
);
3906 Set_Is_Static_Expression
(N
, Rstat
);
3909 -- If the result is not static, then we won't in any case fold
3911 elsif not Rstat
then
3912 Check_Non_Static_Context
(Left
);
3913 Check_Non_Static_Context
(Right
);
3917 -- Here the result is static, note that, unlike the normal processing
3918 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
3919 -- the right operand raises Constraint_Error, that's because it is not
3920 -- significant if the left operand is decisive.
3922 Set_Is_Static_Expression
(N
);
3924 -- It does not matter if the right operand raises Constraint_Error if
3925 -- it will not be evaluated. So deal specially with the cases where
3926 -- the right operand is not evaluated. Note that we will fold these
3927 -- cases even if the right operand is non-static, which is fine, but
3928 -- of course in these cases the result is not potentially static.
3930 Left_Int
:= Expr_Value
(Left
);
3932 if (Kind
= N_And_Then
and then Is_False
(Left_Int
))
3934 (Kind
= N_Or_Else
and then Is_True
(Left_Int
))
3936 Fold_Uint
(N
, Left_Int
, Rstat
);
3940 -- If first operand not decisive, then it does matter if the right
3941 -- operand raises Constraint_Error, since it will be evaluated, so
3942 -- we simply replace the node with the right operand. Note that this
3943 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
3944 -- (both are set to True in Right).
3946 if Raises_Constraint_Error
(Right
) then
3947 Rewrite_In_Raise_CE
(N
, Right
);
3948 Check_Non_Static_Context
(Left
);
3952 -- Otherwise the result depends on the right operand
3954 Fold_Uint
(N
, Expr_Value
(Right
), Rstat
);
3956 end Eval_Short_Circuit
;
3962 -- Slices can never be static, so the only processing required is to check
3963 -- for non-static context if an explicit range is given.
3965 procedure Eval_Slice
(N
: Node_Id
) is
3966 Drange
: constant Node_Id
:= Discrete_Range
(N
);
3967 Name
: constant Node_Id
:= Prefix
(N
);
3970 if Nkind
(Drange
) = N_Range
then
3971 Check_Non_Static_Context
(Low_Bound
(Drange
));
3972 Check_Non_Static_Context
(High_Bound
(Drange
));
3975 -- A slice of the form A (subtype), when the subtype is the index of
3976 -- the type of A, is redundant, the slice can be replaced with A, and
3977 -- this is worth a warning.
3979 if Is_Entity_Name
(Name
) then
3981 E
: constant Entity_Id
:= Entity
(Name
);
3982 T
: constant Entity_Id
:= Etype
(E
);
3986 and then Is_Array_Type
(T
)
3987 and then Is_Entity_Name
(Drange
)
3989 if Is_Entity_Name
(Original_Node
(First_Index
(T
)))
3990 and then Entity
(Original_Node
(First_Index
(T
)))
3993 if Warn_On_Redundant_Constructs
then
3994 Error_Msg_N
("redundant slice denotes whole array?r?", N
);
3997 -- The following might be a useful optimization???
3999 -- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
4006 -------------------------
4007 -- Eval_String_Literal --
4008 -------------------------
4010 procedure Eval_String_Literal
(N
: Node_Id
) is
4011 Typ
: constant Entity_Id
:= Etype
(N
);
4012 Bas
: constant Entity_Id
:= Base_Type
(Typ
);
4018 -- Nothing to do if error type (handles cases like default expressions
4019 -- or generics where we have not yet fully resolved the type).
4021 if Bas
= Any_Type
or else Bas
= Any_String
then
4025 -- String literals are static if the subtype is static (RM 4.9(2)), so
4026 -- reset the static expression flag (it was set unconditionally in
4027 -- Analyze_String_Literal) if the subtype is non-static. We tell if
4028 -- the subtype is static by looking at the lower bound.
4030 if Ekind
(Typ
) = E_String_Literal_Subtype
then
4031 if not Is_OK_Static_Expression
(String_Literal_Low_Bound
(Typ
)) then
4032 Set_Is_Static_Expression
(N
, False);
4036 -- Here if Etype of string literal is normal Etype (not yet possible,
4037 -- but may be possible in future).
4039 elsif not Is_OK_Static_Expression
4040 (Type_Low_Bound
(Etype
(First_Index
(Typ
))))
4042 Set_Is_Static_Expression
(N
, False);
4046 -- If original node was a type conversion, then result if non-static
4047 -- up to Ada 2012. AI12-0201 changes that with Ada 2022.
4049 if Nkind
(Original_Node
(N
)) = N_Type_Conversion
4050 and then Ada_Version
<= Ada_2012
4052 Set_Is_Static_Expression
(N
, False);
4056 -- Test for illegal Ada 95 cases. A string literal is illegal in Ada 95
4057 -- if its bounds are outside the index base type and this index type is
4058 -- static. This can happen in only two ways. Either the string literal
4059 -- is too long, or it is null, and the lower bound is type'First. Either
4060 -- way it is the upper bound that is out of range of the index type.
4062 if Ada_Version
>= Ada_95
then
4063 if Is_Standard_String_Type
(Bas
) then
4064 Xtp
:= Standard_Positive
;
4066 Xtp
:= Etype
(First_Index
(Bas
));
4069 if Ekind
(Typ
) = E_String_Literal_Subtype
then
4070 Lo
:= String_Literal_Low_Bound
(Typ
);
4072 Lo
:= Type_Low_Bound
(Etype
(First_Index
(Typ
)));
4075 -- Check for string too long
4077 Len
:= String_Length
(Strval
(N
));
4079 if Len
> String_Type_Len
(Bas
) then
4081 -- Issue message. Note that this message is a warning if the
4082 -- string literal is not marked as static (happens in some cases
4083 -- of folding strings known at compile time, but not static).
4084 -- Furthermore in such cases, we reword the message, since there
4085 -- is no string literal in the source program.
4087 if Is_Static_Expression
(N
) then
4088 Apply_Compile_Time_Constraint_Error
4089 (N
, "string literal too long for}", CE_Length_Check_Failed
,
4091 Typ
=> First_Subtype
(Bas
));
4093 Apply_Compile_Time_Constraint_Error
4094 (N
, "string value too long for}", CE_Length_Check_Failed
,
4096 Typ
=> First_Subtype
(Bas
),
4100 -- Test for null string not allowed
4103 and then not Is_Generic_Type
(Xtp
)
4105 Expr_Value
(Lo
) = Expr_Value
(Type_Low_Bound
(Base_Type
(Xtp
)))
4107 -- Same specialization of message
4109 if Is_Static_Expression
(N
) then
4110 Apply_Compile_Time_Constraint_Error
4111 (N
, "null string literal not allowed for}",
4112 CE_Length_Check_Failed
,
4114 Typ
=> First_Subtype
(Bas
));
4116 Apply_Compile_Time_Constraint_Error
4117 (N
, "null string value not allowed for}",
4118 CE_Length_Check_Failed
,
4120 Typ
=> First_Subtype
(Bas
),
4125 end Eval_String_Literal
;
4127 --------------------------
4128 -- Eval_Type_Conversion --
4129 --------------------------
4131 -- A type conversion is potentially static if its subtype mark is for a
4132 -- static scalar subtype, and its operand expression is potentially static
4134 -- Also add support for static string types.
4136 procedure Eval_Type_Conversion
(N
: Node_Id
) is
4137 Operand
: constant Node_Id
:= Expression
(N
);
4138 Source_Type
: constant Entity_Id
:= Etype
(Operand
);
4139 Target_Type
: constant Entity_Id
:= Etype
(N
);
4141 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean;
4142 -- Returns true if type T is an integer type, or if it is a fixed-point
4143 -- type to be treated as an integer (i.e. the flag Conversion_OK is set
4144 -- on the conversion node).
4146 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean;
4147 -- Returns true if type T is a floating-point type, or if it is a
4148 -- fixed-point type that is not to be treated as an integer (i.e. the
4149 -- flag Conversion_OK is not set on the conversion node).
4151 ------------------------------
4152 -- To_Be_Treated_As_Integer --
4153 ------------------------------
4155 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean is
4159 or else (Is_Fixed_Point_Type
(T
) and then Conversion_OK
(N
));
4160 end To_Be_Treated_As_Integer
;
4162 ---------------------------
4163 -- To_Be_Treated_As_Real --
4164 ---------------------------
4166 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean is
4169 Is_Floating_Point_Type
(T
)
4170 or else (Is_Fixed_Point_Type
(T
) and then not Conversion_OK
(N
));
4171 end To_Be_Treated_As_Real
;
4178 -- Start of processing for Eval_Type_Conversion
4181 -- Cannot fold if target type is non-static or if semantic error
4183 if not Is_Static_Subtype
(Target_Type
) then
4184 Check_Non_Static_Context
(Operand
);
4186 elsif Error_Posted
(N
) then
4190 -- If not foldable we are done
4192 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
4197 -- Don't try fold if target type has Constraint_Error bounds
4199 elsif not Is_OK_Static_Subtype
(Target_Type
) then
4200 Set_Raises_Constraint_Error
(N
);
4204 -- Remaining processing depends on operand types. Note that in the
4205 -- following type test, fixed-point counts as real unless the flag
4206 -- Conversion_OK is set, in which case it counts as integer.
4208 -- Fold conversion, case of string type. The result is static starting
4209 -- with Ada 2022 (AI12-0201).
4211 if Is_String_Type
(Target_Type
) then
4214 Strval
(Get_String_Val
(Operand
)),
4215 Static
=> Ada_Version
>= Ada_2022
);
4218 -- Fold conversion, case of integer target type
4220 elsif To_Be_Treated_As_Integer
(Target_Type
) then
4225 -- Integer to integer conversion
4227 if To_Be_Treated_As_Integer
(Source_Type
) then
4228 Result
:= Expr_Value
(Operand
);
4230 -- Real to integer conversion
4232 elsif To_Be_Treated_As_Real
(Source_Type
) then
4233 Result
:= UR_To_Uint
(Expr_Value_R
(Operand
));
4235 -- Enumeration to integer conversion, aka 'Enum_Rep
4238 Result
:= Expr_Rep_Value
(Operand
);
4241 -- If fixed-point type (Conversion_OK must be set), then the
4242 -- result is logically an integer, but we must replace the
4243 -- conversion with the corresponding real literal, since the
4244 -- type from a semantic point of view is still fixed-point.
4246 if Is_Fixed_Point_Type
(Target_Type
) then
4248 (N
, UR_From_Uint
(Result
) * Small_Value
(Target_Type
), Stat
);
4250 -- Otherwise result is integer literal
4253 Fold_Uint
(N
, Result
, Stat
);
4257 -- Fold conversion, case of real target type
4259 elsif To_Be_Treated_As_Real
(Target_Type
) then
4264 if To_Be_Treated_As_Real
(Source_Type
) then
4265 Result
:= Expr_Value_R
(Operand
);
4267 Result
:= UR_From_Uint
(Expr_Value
(Operand
));
4270 Fold_Ureal
(N
, Result
, Stat
);
4273 -- Enumeration types
4276 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
4279 -- If the target is a static floating-point subtype, then its bounds
4280 -- are machine numbers so we must consider the machine-rounded value.
4282 if Is_Floating_Point_Type
(Target_Type
)
4283 and then Nkind
(N
) = N_Real_Literal
4284 and then not Is_Machine_Number
(N
)
4287 Lo
: constant Node_Id
:= Type_Low_Bound
(Target_Type
);
4288 Hi
: constant Node_Id
:= Type_High_Bound
(Target_Type
);
4289 Valr
: constant Ureal
:=
4290 Machine_Number
(Target_Type
, Expr_Value_R
(N
), N
);
4292 if Valr
< Expr_Value_R
(Lo
) or else Valr
> Expr_Value_R
(Hi
) then
4297 elsif Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
4300 end Eval_Type_Conversion
;
4306 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
4307 -- are potentially static if the operand is potentially static (RM 4.9(7)).
4309 procedure Eval_Unary_Op
(N
: Node_Id
) is
4310 Right
: constant Node_Id
:= Right_Opnd
(N
);
4311 Otype
: Entity_Id
:= Empty
;
4316 -- If not foldable we are done
4318 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
4324 if Is_Universal_Numeric_Type
(Etype
(Right
)) then
4325 Otype
:= Find_Universal_Operator_Type
(N
);
4328 -- Fold for integer case
4330 if Is_Integer_Type
(Etype
(N
)) then
4332 Rint
: constant Uint
:= Expr_Value
(Right
);
4336 -- In the case of modular unary plus and abs there is no need
4337 -- to adjust the result of the operation since if the original
4338 -- operand was in bounds the result will be in the bounds of the
4339 -- modular type. However, in the case of modular unary minus the
4340 -- result may go out of the bounds of the modular type and needs
4343 if Nkind
(N
) = N_Op_Plus
then
4346 elsif Nkind
(N
) = N_Op_Minus
then
4347 if Is_Modular_Integer_Type
(Etype
(N
)) then
4348 Result
:= (-Rint
) mod Modulus
(Etype
(N
));
4354 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
4358 Check_Non_Static_Context_For_Overflow
(N
, Stat
, Result
);
4360 Fold_Uint
(N
, Result
, Stat
);
4363 -- Fold for real case
4365 elsif Is_Real_Type
(Etype
(N
)) then
4367 Rreal
: constant Ureal
:= Expr_Value_R
(Right
);
4371 if Nkind
(N
) = N_Op_Plus
then
4373 elsif Nkind
(N
) = N_Op_Minus
then
4374 Result
:= UR_Negate
(Rreal
);
4376 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
4377 Result
:= abs Rreal
;
4380 Fold_Ureal
(N
, Result
, Stat
);
4384 -- If the operator was resolved to a specific type, make sure that type
4385 -- is frozen even if the expression is folded into a literal (which has
4386 -- a universal type).
4388 if Present
(Otype
) then
4389 Freeze_Before
(N
, Otype
);
4393 -------------------------------
4394 -- Eval_Unchecked_Conversion --
4395 -------------------------------
4397 -- Unchecked conversions can never be static, so the only required
4398 -- processing is to check for a non-static context for the operand.
4400 procedure Eval_Unchecked_Conversion
(N
: Node_Id
) is
4401 Target_Type
: constant Entity_Id
:= Etype
(N
);
4402 Operand
: constant Node_Id
:= Expression
(N
);
4403 Operand_Type
: constant Entity_Id
:= Etype
(Operand
);
4406 Check_Non_Static_Context
(Operand
);
4408 -- If we have a conversion of a compile time known value to a target
4409 -- type and the value is in range of the target type, then we can simply
4410 -- replace the construct by an integer literal of the correct type. We
4411 -- only apply this to discrete types being converted. Possibly it may
4412 -- apply in other cases, but it is too much trouble to worry about.
4414 -- Note that we do not do this transformation if the Kill_Range_Check
4415 -- flag is set, since then the value may be outside the expected range.
4416 -- This happens in the Normalize_Scalars case.
4418 -- We also skip this if either the target or operand type is biased
4419 -- because in this case, the unchecked conversion is supposed to
4420 -- preserve the bit pattern, not the integer value.
4422 if Is_Integer_Type
(Target_Type
)
4423 and then not Has_Biased_Representation
(Target_Type
)
4424 and then Is_Discrete_Type
(Operand_Type
)
4425 and then not Has_Biased_Representation
(Operand_Type
)
4426 and then Compile_Time_Known_Value
(Operand
)
4427 and then not Kill_Range_Check
(N
)
4430 Val
: constant Uint
:= Expr_Rep_Value
(Operand
);
4433 if Compile_Time_Known_Value
(Type_Low_Bound
(Target_Type
))
4435 Compile_Time_Known_Value
(Type_High_Bound
(Target_Type
))
4437 Val
>= Expr_Value
(Type_Low_Bound
(Target_Type
))
4439 Val
<= Expr_Value
(Type_High_Bound
(Target_Type
))
4441 Rewrite
(N
, Make_Integer_Literal
(Sloc
(N
), Val
));
4443 -- If Address is the target type, just set the type to avoid a
4444 -- spurious type error on the literal when Address is a visible
4447 if Is_Descendant_Of_Address
(Target_Type
) then
4448 Set_Etype
(N
, Target_Type
);
4450 Analyze_And_Resolve
(N
, Target_Type
);
4457 end Eval_Unchecked_Conversion
;
4459 --------------------
4460 -- Expr_Rep_Value --
4461 --------------------
4463 function Expr_Rep_Value
(N
: Node_Id
) return Uint
is
4464 Kind
: constant Node_Kind
:= Nkind
(N
);
4468 if Is_Entity_Name
(N
) then
4471 -- An enumeration literal that was either in the source or created
4472 -- as a result of static evaluation.
4474 if Ekind
(Ent
) = E_Enumeration_Literal
then
4475 return Enumeration_Rep
(Ent
);
4477 -- A user defined static constant
4480 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4481 return Expr_Rep_Value
(Constant_Value
(Ent
));
4484 -- An integer literal that was either in the source or created as a
4485 -- result of static evaluation.
4487 elsif Kind
= N_Integer_Literal
then
4490 -- A real literal for a fixed-point type. This must be the fixed-point
4491 -- case, either the literal is of a fixed-point type, or it is a bound
4492 -- of a fixed-point type, with type universal real. In either case we
4493 -- obtain the desired value from Corresponding_Integer_Value.
4495 elsif Kind
= N_Real_Literal
then
4496 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
4497 return Corresponding_Integer_Value
(N
);
4499 -- The NULL access value
4501 elsif Kind
= N_Null
then
4502 pragma Assert
(Is_Access_Type
(Underlying_Type
(Etype
(N
)))
4503 or else Error_Posted
(N
));
4506 -- Character literal
4508 elsif Kind
= N_Character_Literal
then
4511 -- Since Character literals of type Standard.Character don't have any
4512 -- defining character literals built for them, they do not have their
4513 -- Entity set, so just use their Char code. Otherwise for user-
4514 -- defined character literals use their Pos value as usual which is
4515 -- the same as the Rep value.
4518 return Char_Literal_Value
(N
);
4520 return Enumeration_Rep
(Ent
);
4523 -- Unchecked conversion, which can come from System'To_Address (X)
4524 -- where X is a static integer expression. Recursively evaluate X.
4526 elsif Kind
= N_Unchecked_Type_Conversion
then
4527 return Expr_Rep_Value
(Expression
(N
));
4529 -- Static discriminant value
4531 elsif Is_Static_Discriminant_Component
(N
) then
4532 return Expr_Rep_Value
4533 (Get_Discriminant_Value
4534 (Entity
(Selector_Name
(N
)),
4536 Discriminant_Constraint
(Etype
(Prefix
(N
)))));
4539 raise Program_Error
;
4547 function Expr_Value
(N
: Node_Id
) return Uint
is
4548 Kind
: constant Node_Kind
:= Nkind
(N
);
4549 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(N
) mod CV_Cache_Size
);
4554 -- If already in cache, then we know it's compile-time-known and we can
4555 -- return the value that was previously stored in the cache since
4556 -- compile-time-known values cannot change.
4558 if CV_Ent
.N
= N
then
4562 -- Otherwise proceed to test value
4564 if Is_Entity_Name
(N
) then
4567 -- An enumeration literal that was either in the source or created as
4568 -- a result of static evaluation.
4570 if Ekind
(Ent
) = E_Enumeration_Literal
then
4571 Val
:= Enumeration_Pos
(Ent
);
4573 -- A user defined static constant
4576 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4577 Val
:= Expr_Value
(Constant_Value
(Ent
));
4580 -- An integer literal that was either in the source or created as a
4581 -- result of static evaluation.
4583 elsif Kind
= N_Integer_Literal
then
4586 -- A real literal for a fixed-point type. This must be the fixed-point
4587 -- case, either the literal is of a fixed-point type, or it is a bound
4588 -- of a fixed-point type, with type universal real. In either case we
4589 -- obtain the desired value from Corresponding_Integer_Value.
4591 elsif Kind
= N_Real_Literal
then
4592 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
4593 Val
:= Corresponding_Integer_Value
(N
);
4595 -- The NULL access value
4597 elsif Kind
= N_Null
then
4598 pragma Assert
(Is_Access_Type
(Underlying_Type
(Etype
(N
)))
4599 or else Error_Posted
(N
));
4602 -- Character literal
4604 elsif Kind
= N_Character_Literal
then
4607 -- Since Character literals of type Standard.Character don't
4608 -- have any defining character literals built for them, they
4609 -- do not have their Entity set, so just use their Char
4610 -- code. Otherwise for user-defined character literals use
4611 -- their Pos value as usual.
4614 Val
:= Char_Literal_Value
(N
);
4616 Val
:= Enumeration_Pos
(Ent
);
4619 -- Unchecked conversion, which can come from System'To_Address (X)
4620 -- where X is a static integer expression. Recursively evaluate X.
4622 elsif Kind
= N_Unchecked_Type_Conversion
then
4623 Val
:= Expr_Value
(Expression
(N
));
4625 -- Static discriminant value
4627 elsif Is_Static_Discriminant_Component
(N
) then
4629 (Get_Discriminant_Value
4630 (Entity
(Selector_Name
(N
)),
4632 Discriminant_Constraint
(Etype
(Prefix
(N
)))));
4635 raise Program_Error
;
4638 -- Come here with Val set to value to be returned, set cache
4649 function Expr_Value_E
(N
: Node_Id
) return Entity_Id
is
4650 Ent
: constant Entity_Id
:= Entity
(N
);
4652 if Ekind
(Ent
) = E_Enumeration_Literal
then
4655 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4657 -- We may be dealing with a enumerated character type constant, so
4658 -- handle that case here.
4660 if Nkind
(Constant_Value
(Ent
)) = N_Character_Literal
then
4663 return Expr_Value_E
(Constant_Value
(Ent
));
4672 function Expr_Value_R
(N
: Node_Id
) return Ureal
is
4673 Kind
: constant Node_Kind
:= Nkind
(N
);
4677 if Kind
= N_Real_Literal
then
4680 elsif Kind
= N_Identifier
or else Kind
= N_Expanded_Name
then
4682 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4683 return Expr_Value_R
(Constant_Value
(Ent
));
4685 elsif Kind
= N_Integer_Literal
then
4686 return UR_From_Uint
(Expr_Value
(N
));
4688 -- Here, we have a node that cannot be interpreted as a compile time
4689 -- constant. That is definitely an error.
4692 raise Program_Error
;
4700 function Expr_Value_S
(N
: Node_Id
) return Node_Id
is
4702 if Nkind
(N
) = N_String_Literal
then
4705 pragma Assert
(Ekind
(Entity
(N
)) = E_Constant
);
4706 return Expr_Value_S
(Constant_Value
(Entity
(N
)));
4710 ----------------------------------
4711 -- Find_Universal_Operator_Type --
4712 ----------------------------------
4714 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
is
4715 PN
: constant Node_Id
:= Parent
(N
);
4716 Call
: constant Node_Id
:= Original_Node
(N
);
4717 Is_Int
: constant Boolean := Is_Integer_Type
(Etype
(N
));
4719 Is_Fix
: constant Boolean :=
4720 Nkind
(N
) in N_Binary_Op
4721 and then Nkind
(Right_Opnd
(N
)) /= Nkind
(Left_Opnd
(N
));
4722 -- A mixed-mode operation in this context indicates the presence of
4723 -- fixed-point type in the designated package.
4725 Is_Relational
: constant Boolean := Etype
(N
) = Standard_Boolean
;
4726 -- Case where N is a relational (or membership) operator (else it is an
4729 In_Membership
: constant Boolean :=
4730 Nkind
(PN
) in N_Membership_Test
4732 Nkind
(Right_Opnd
(PN
)) = N_Range
4734 Is_Universal_Numeric_Type
(Etype
(Left_Opnd
(PN
)))
4736 Is_Universal_Numeric_Type
4737 (Etype
(Low_Bound
(Right_Opnd
(PN
))))
4739 Is_Universal_Numeric_Type
4740 (Etype
(High_Bound
(Right_Opnd
(PN
))));
4741 -- Case where N is part of a membership test with a universal range
4745 Typ1
: Entity_Id
:= Empty
;
4748 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean;
4749 -- Check whether one operand is a mixed-mode operation that requires the
4750 -- presence of a fixed-point type. Given that all operands are universal
4751 -- and have been constant-folded, retrieve the original function call.
4753 ---------------------------
4754 -- Is_Mixed_Mode_Operand --
4755 ---------------------------
4757 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean is
4758 Onod
: constant Node_Id
:= Original_Node
(Op
);
4760 return Nkind
(Onod
) = N_Function_Call
4761 and then Present
(Next_Actual
(First_Actual
(Onod
)))
4762 and then Etype
(First_Actual
(Onod
)) /=
4763 Etype
(Next_Actual
(First_Actual
(Onod
)));
4764 end Is_Mixed_Mode_Operand
;
4766 -- Start of processing for Find_Universal_Operator_Type
4769 if Nkind
(Call
) /= N_Function_Call
4770 or else Nkind
(Name
(Call
)) /= N_Expanded_Name
4774 -- There are several cases where the context does not imply the type of
4776 -- - the universal expression appears in a type conversion;
4777 -- - the expression is a relational operator applied to universal
4779 -- - the expression is a membership test with a universal operand
4780 -- and a range with universal bounds.
4782 elsif Nkind
(Parent
(N
)) = N_Type_Conversion
4783 or else Is_Relational
4784 or else In_Membership
4786 Pack
:= Entity
(Prefix
(Name
(Call
)));
4788 -- If the prefix is a package declared elsewhere, iterate over its
4789 -- visible entities, otherwise iterate over all declarations in the
4790 -- designated scope.
4792 if Ekind
(Pack
) = E_Package
4793 and then not In_Open_Scopes
(Pack
)
4795 Priv_E
:= First_Private_Entity
(Pack
);
4801 E
:= First_Entity
(Pack
);
4802 while Present
(E
) and then E
/= Priv_E
loop
4803 if Is_Numeric_Type
(E
)
4804 and then Nkind
(Parent
(E
)) /= N_Subtype_Declaration
4805 and then Comes_From_Source
(E
)
4806 and then Is_Integer_Type
(E
) = Is_Int
4807 and then (Nkind
(N
) in N_Unary_Op
4808 or else Is_Relational
4809 or else Is_Fixed_Point_Type
(E
) = Is_Fix
)
4814 -- Before emitting an error, check for the presence of a
4815 -- mixed-mode operation that specifies a fixed point type.
4819 (Is_Mixed_Mode_Operand
(Left_Opnd
(N
))
4820 or else Is_Mixed_Mode_Operand
(Right_Opnd
(N
)))
4821 and then Is_Fixed_Point_Type
(E
) /= Is_Fixed_Point_Type
(Typ1
)
4824 if Is_Fixed_Point_Type
(E
) then
4829 -- More than one type of the proper class declared in P
4831 Error_Msg_N
("ambiguous operation", N
);
4832 Error_Msg_Sloc
:= Sloc
(Typ1
);
4833 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4834 Error_Msg_Sloc
:= Sloc
(E
);
4835 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4845 end Find_Universal_Operator_Type
;
4847 --------------------------
4848 -- Flag_Non_Static_Expr --
4849 --------------------------
4851 procedure Flag_Non_Static_Expr
(Msg
: String; Expr
: Node_Id
) is
4853 if Error_Posted
(Expr
) and then not All_Errors_Mode
then
4856 Error_Msg_F
(Msg
, Expr
);
4857 Why_Not_Static
(Expr
);
4859 end Flag_Non_Static_Expr
;
4865 procedure Fold
(N
: Node_Id
) is
4866 Typ
: constant Entity_Id
:= Etype
(N
);
4868 -- If not known at compile time or if already a literal, nothing to do
4870 if Nkind
(N
) in N_Numeric_Or_String_Literal
4871 or else not Compile_Time_Known_Value
(N
)
4875 elsif Is_Discrete_Type
(Typ
) then
4876 Fold_Uint
(N
, Expr_Value
(N
), Static
=> Is_Static_Expression
(N
));
4878 elsif Is_Real_Type
(Typ
) then
4879 Fold_Ureal
(N
, Expr_Value_R
(N
), Static
=> Is_Static_Expression
(N
));
4881 elsif Is_String_Type
(Typ
) then
4883 (N
, Strval
(Expr_Value_S
(N
)), Static
=> Is_Static_Expression
(N
));
4891 procedure Fold_Dummy
(N
: Node_Id
; Typ
: Entity_Id
) is
4893 if Is_Integer_Type
(Typ
) then
4894 Fold_Uint
(N
, Uint_1
, Static
=> True);
4896 elsif Is_Real_Type
(Typ
) then
4897 Fold_Ureal
(N
, Ureal_1
, Static
=> True);
4899 elsif Is_Enumeration_Type
(Typ
) then
4902 Expr_Value
(Type_Low_Bound
(Base_Type
(Typ
))),
4905 elsif Is_String_Type
(Typ
) then
4908 Strval
(Make_String_Literal
(Sloc
(N
), "")),
4917 procedure Fold_Shift
4922 Static
: Boolean := False;
4923 Check_Elab
: Boolean := False)
4925 Typ
: constant Entity_Id
:= Base_Type
(Etype
(Left
));
4927 procedure Check_Elab_Call
;
4928 -- Add checks related to calls in elaboration code
4930 ---------------------
4931 -- Check_Elab_Call --
4932 ---------------------
4934 procedure Check_Elab_Call
is
4937 if Legacy_Elaboration_Checks
then
4938 Check_Elab_Call
(N
);
4941 Build_Call_Marker
(N
);
4943 end Check_Elab_Call
;
4945 Modulus
, Val
: Uint
;
4948 if Compile_Time_Known_Value
(Left
)
4949 and then Compile_Time_Known_Value
(Right
)
4951 pragma Assert
(not Non_Binary_Modulus
(Typ
));
4953 if Op
= N_Op_Shift_Left
then
4956 if Is_Modular_Integer_Type
(Typ
) then
4957 Modulus
:= Einfo
.Entities
.Modulus
(Typ
);
4959 Modulus
:= Uint_2
** RM_Size
(Typ
);
4962 -- Fold Shift_Left (X, Y) by computing
4963 -- (X * 2**Y) rem modulus [- Modulus]
4965 Val
:= (Expr_Value
(Left
) * (Uint_2
** Expr_Value
(Right
)))
4968 if Is_Modular_Integer_Type
(Typ
)
4969 or else Val
< Modulus
/ Uint_2
4971 Fold_Uint
(N
, Val
, Static
=> Static
);
4973 Fold_Uint
(N
, Val
- Modulus
, Static
=> Static
);
4976 elsif Op
= N_Op_Shift_Right
then
4979 -- X >> 0 is a no-op
4981 if Expr_Value
(Right
) = Uint_0
then
4982 Fold_Uint
(N
, Expr_Value
(Left
), Static
=> Static
);
4984 if Is_Modular_Integer_Type
(Typ
) then
4985 Modulus
:= Einfo
.Entities
.Modulus
(Typ
);
4987 Modulus
:= Uint_2
** RM_Size
(Typ
);
4990 -- Fold X >> Y by computing (X [+ Modulus]) / 2**Y
4991 -- Note that after a Shift_Right operation (with Y > 0), the
4992 -- result is always positive, even if the original operand was
4998 if Expr_Value
(Left
) >= Uint_0
then
5006 (Expr_Value
(Left
) + M
) / (Uint_2
** Expr_Value
(Right
)),
5010 elsif Op
= N_Op_Shift_Right_Arithmetic
then
5014 Two_Y
: constant Uint
:= Uint_2
** Expr_Value
(Right
);
5016 if Is_Modular_Integer_Type
(Typ
) then
5017 Modulus
:= Einfo
.Entities
.Modulus
(Typ
);
5019 Modulus
:= Uint_2
** RM_Size
(Typ
);
5022 -- X / 2**Y if X if positive or a small enough modular integer
5024 if (Is_Modular_Integer_Type
(Typ
)
5025 and then Expr_Value
(Left
) < Modulus
/ Uint_2
)
5027 (not Is_Modular_Integer_Type
(Typ
)
5028 and then Expr_Value
(Left
) >= 0)
5030 Fold_Uint
(N
, Expr_Value
(Left
) / Two_Y
, Static
=> Static
);
5032 -- -1 (aka all 1's) if Y is larger than the number of bits
5033 -- available or if X = -1.
5035 elsif Two_Y
> Modulus
5036 or else Expr_Value
(Left
) = Uint_Minus_1
5038 if Is_Modular_Integer_Type
(Typ
) then
5039 Fold_Uint
(N
, Modulus
- Uint_1
, Static
=> Static
);
5041 Fold_Uint
(N
, Uint_Minus_1
, Static
=> Static
);
5044 -- Large modular integer, compute via multiply/divide the
5045 -- following: X >> Y + (1 << Y - 1) << (RM_Size - Y)
5047 elsif Is_Modular_Integer_Type
(Typ
) then
5050 (Expr_Value
(Left
)) / Two_Y
5052 * Uint_2
** (RM_Size
(Typ
) - Expr_Value
(Right
)),
5055 -- Negative signed integer, compute via multiple/divide the
5057 -- (Modulus + X) >> Y + (1 << Y - 1) << (RM_Size - Y) - Modulus
5062 (Modulus
+ Expr_Value
(Left
)) / Two_Y
5064 * Uint_2
** (RM_Size
(Typ
) - Expr_Value
(Right
))
5077 procedure Fold_Str
(N
: Node_Id
; Val
: String_Id
; Static
: Boolean) is
5078 Loc
: constant Source_Ptr
:= Sloc
(N
);
5079 Typ
: constant Entity_Id
:= Etype
(N
);
5082 if Raises_Constraint_Error
(N
) then
5083 Set_Is_Static_Expression
(N
, Static
);
5087 Rewrite
(N
, Make_String_Literal
(Loc
, Strval
=> Val
));
5089 -- We now have the literal with the right value, both the actual type
5090 -- and the expected type of this literal are taken from the expression
5091 -- that was evaluated. So now we do the Analyze and Resolve.
5093 -- Note that we have to reset Is_Static_Expression both after the
5094 -- analyze step (because Resolve will evaluate the literal, which
5095 -- will cause semantic errors if it is marked as static), and after
5096 -- the Resolve step (since Resolve in some cases resets this flag).
5099 Set_Is_Static_Expression
(N
, Static
);
5102 Set_Is_Static_Expression
(N
, Static
);
5109 procedure Fold_Uint
(N
: Node_Id
; Val
: Uint
; Static
: Boolean) is
5110 Loc
: constant Source_Ptr
:= Sloc
(N
);
5111 Typ
: Entity_Id
:= Etype
(N
);
5115 if Raises_Constraint_Error
(N
) then
5116 Set_Is_Static_Expression
(N
, Static
);
5120 -- If we are folding a named number, retain the entity in the literal
5121 -- in the original tree.
5123 if Is_Entity_Name
(N
) and then Ekind
(Entity
(N
)) = E_Named_Integer
then
5129 if Is_Private_Type
(Typ
) then
5130 Typ
:= Full_View
(Typ
);
5133 -- For a result of type integer, substitute an N_Integer_Literal node
5134 -- for the result of the compile time evaluation of the expression.
5135 -- Set a link to the original named number when not in a generic context
5136 -- for reference in the original tree.
5138 if Is_Integer_Type
(Typ
) then
5139 Rewrite
(N
, Make_Integer_Literal
(Loc
, Val
));
5140 Set_Original_Entity
(N
, Ent
);
5142 -- Otherwise we have an enumeration type, and we substitute either
5143 -- an N_Identifier or N_Character_Literal to represent the enumeration
5144 -- literal corresponding to the given value, which must always be in
5145 -- range, because appropriate tests have already been made for this.
5147 else pragma Assert
(Is_Enumeration_Type
(Typ
));
5148 Rewrite
(N
, Get_Enum_Lit_From_Pos
(Etype
(N
), Val
, Loc
));
5151 -- We now have the literal with the right value, both the actual type
5152 -- and the expected type of this literal are taken from the expression
5153 -- that was evaluated. So now we do the Analyze and Resolve.
5155 -- Note that we have to reset Is_Static_Expression both after the
5156 -- analyze step (because Resolve will evaluate the literal, which
5157 -- will cause semantic errors if it is marked as static), and after
5158 -- the Resolve step (since Resolve in some cases sets this flag).
5161 Set_Is_Static_Expression
(N
, Static
);
5164 Set_Is_Static_Expression
(N
, Static
);
5171 procedure Fold_Ureal
(N
: Node_Id
; Val
: Ureal
; Static
: Boolean) is
5172 Loc
: constant Source_Ptr
:= Sloc
(N
);
5173 Typ
: constant Entity_Id
:= Etype
(N
);
5177 if Raises_Constraint_Error
(N
) then
5178 Set_Is_Static_Expression
(N
, Static
);
5182 -- If we are folding a named number, retain the entity in the literal
5183 -- in the original tree.
5185 if Is_Entity_Name
(N
) and then Ekind
(Entity
(N
)) = E_Named_Real
then
5191 Rewrite
(N
, Make_Real_Literal
(Loc
, Realval
=> Val
));
5193 -- Set link to original named number
5195 Set_Original_Entity
(N
, Ent
);
5197 -- We now have the literal with the right value, both the actual type
5198 -- and the expected type of this literal are taken from the expression
5199 -- that was evaluated. So now we do the Analyze and Resolve.
5201 -- Note that we have to reset Is_Static_Expression both after the
5202 -- analyze step (because Resolve will evaluate the literal, which
5203 -- will cause semantic errors if it is marked as static), and after
5204 -- the Resolve step (since Resolve in some cases sets this flag).
5206 -- We mark the node as analyzed so that its type is not erased by
5207 -- calling Analyze_Real_Literal.
5210 Set_Is_Static_Expression
(N
, Static
);
5214 Set_Is_Static_Expression
(N
, Static
);
5221 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
is
5225 for J
in 0 .. B
'Last loop
5231 if Non_Binary_Modulus
(T
) then
5232 V
:= V
mod Modulus
(T
);
5238 --------------------
5239 -- Get_String_Val --
5240 --------------------
5242 function Get_String_Val
(N
: Node_Id
) return Node_Id
is
5244 if Nkind
(N
) in N_String_Literal | N_Character_Literal
then
5247 pragma Assert
(Is_Entity_Name
(N
));
5248 return Get_String_Val
(Constant_Value
(Entity
(N
)));
5256 procedure Initialize
is
5258 CV_Cache
:= (others => (Node_High_Bound
, Uint_0
));
5261 --------------------
5262 -- In_Subrange_Of --
5263 --------------------
5265 function In_Subrange_Of
5268 Fixed_Int
: Boolean := False) return Boolean
5277 if T1
= T2
or else Is_Subtype_Of
(T1
, T2
) then
5280 -- Never in range if both types are not scalar. Don't know if this can
5281 -- actually happen, but just in case.
5283 elsif not Is_Scalar_Type
(T1
) or else not Is_Scalar_Type
(T2
) then
5286 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
5287 -- definitely not compatible with T2.
5289 elsif Is_Floating_Point_Type
(T1
)
5290 and then Has_Infinities
(T1
)
5291 and then Is_Floating_Point_Type
(T2
)
5292 and then not Has_Infinities
(T2
)
5297 L1
:= Type_Low_Bound
(T1
);
5298 H1
:= Type_High_Bound
(T1
);
5300 L2
:= Type_Low_Bound
(T2
);
5301 H2
:= Type_High_Bound
(T2
);
5303 -- Check bounds to see if comparison possible at compile time
5305 if Compile_Time_Compare
(L1
, L2
, Assume_Valid
=> True) in Compare_GE
5307 Compile_Time_Compare
(H1
, H2
, Assume_Valid
=> True) in Compare_LE
5312 -- If bounds not comparable at compile time, then the bounds of T2
5313 -- must be compile-time-known or we cannot answer the query.
5315 if not Compile_Time_Known_Value
(L2
)
5316 or else not Compile_Time_Known_Value
(H2
)
5321 -- If the bounds of T1 are know at compile time then use these
5322 -- ones, otherwise use the bounds of the base type (which are of
5323 -- course always static).
5325 if not Compile_Time_Known_Value
(L1
) then
5326 L1
:= Type_Low_Bound
(Base_Type
(T1
));
5329 if not Compile_Time_Known_Value
(H1
) then
5330 H1
:= Type_High_Bound
(Base_Type
(T1
));
5333 -- Fixed point types should be considered as such only if
5334 -- flag Fixed_Int is set to False.
5336 if Is_Floating_Point_Type
(T1
) or else Is_Floating_Point_Type
(T2
)
5337 or else (Is_Fixed_Point_Type
(T1
) and then not Fixed_Int
)
5338 or else (Is_Fixed_Point_Type
(T2
) and then not Fixed_Int
)
5341 Expr_Value_R
(L2
) <= Expr_Value_R
(L1
)
5343 Expr_Value_R
(H2
) >= Expr_Value_R
(H1
);
5347 Expr_Value
(L2
) <= Expr_Value
(L1
)
5349 Expr_Value
(H2
) >= Expr_Value
(H1
);
5354 -- If any exception occurs, it means that we have some bug in the compiler
5355 -- possibly triggered by a previous error, or by some unforeseen peculiar
5356 -- occurrence. However, this is only an optimization attempt, so there is
5357 -- really no point in crashing the compiler. Instead we just decide, too
5358 -- bad, we can't figure out the answer in this case after all.
5362 -- With debug flag K we will get an exception unless an error has
5363 -- already occurred (useful for debugging).
5365 if Debug_Flag_K
then
5366 Check_Error_Detected
;
5376 function Is_In_Range
5379 Assume_Valid
: Boolean := False;
5380 Fixed_Int
: Boolean := False;
5381 Int_Real
: Boolean := False) return Boolean
5385 Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
) = In_Range
;
5392 function Is_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
5394 if Compile_Time_Known_Value
(Lo
)
5395 and then Compile_Time_Known_Value
(Hi
)
5398 Typ
: Entity_Id
:= Etype
(Lo
);
5400 -- When called from the frontend, as part of the analysis of
5401 -- potentially static expressions, Typ will be the full view of a
5402 -- type with all the info needed to answer this query. When called
5403 -- from the backend, for example to know whether a range of a loop
5404 -- is null, Typ might be a private type and we need to explicitly
5405 -- switch to its corresponding full view to access the same info.
5407 if Is_Incomplete_Or_Private_Type
(Typ
)
5408 and then Present
(Full_View
(Typ
))
5410 Typ
:= Full_View
(Typ
);
5413 if Is_Discrete_Type
(Typ
) then
5414 return Expr_Value
(Lo
) > Expr_Value
(Hi
);
5415 else pragma Assert
(Is_Real_Type
(Typ
));
5416 return Expr_Value_R
(Lo
) > Expr_Value_R
(Hi
);
5424 -------------------------
5425 -- Is_OK_Static_Choice --
5426 -------------------------
5428 function Is_OK_Static_Choice
(Choice
: Node_Id
) return Boolean is
5430 -- Check various possibilities for choice
5432 -- Note: for membership tests, we test more cases than are possible
5433 -- (in particular subtype indication), but it doesn't matter because
5434 -- it just won't occur (we have already done a syntax check).
5436 if Nkind
(Choice
) = N_Others_Choice
then
5439 elsif Nkind
(Choice
) = N_Range
then
5440 return Is_OK_Static_Range
(Choice
);
5442 elsif Nkind
(Choice
) = N_Subtype_Indication
5443 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
5445 return Is_OK_Static_Subtype
(Etype
(Choice
));
5448 return Is_OK_Static_Expression
(Choice
);
5450 end Is_OK_Static_Choice
;
5452 ------------------------------
5453 -- Is_OK_Static_Choice_List --
5454 ------------------------------
5456 function Is_OK_Static_Choice_List
(Choices
: List_Id
) return Boolean is
5460 if not Is_Static_Choice_List
(Choices
) then
5464 Choice
:= First
(Choices
);
5465 while Present
(Choice
) loop
5466 if not Is_OK_Static_Choice
(Choice
) then
5467 Set_Raises_Constraint_Error
(Choice
);
5475 end Is_OK_Static_Choice_List
;
5477 -----------------------------
5478 -- Is_OK_Static_Expression --
5479 -----------------------------
5481 function Is_OK_Static_Expression
(N
: Node_Id
) return Boolean is
5483 return Is_Static_Expression
(N
) and then not Raises_Constraint_Error
(N
);
5484 end Is_OK_Static_Expression
;
5486 ------------------------
5487 -- Is_OK_Static_Range --
5488 ------------------------
5490 -- A static range is a range whose bounds are static expressions, or a
5491 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
5492 -- We have already converted range attribute references, so we get the
5493 -- "or" part of this rule without needing a special test.
5495 function Is_OK_Static_Range
(N
: Node_Id
) return Boolean is
5497 return Is_OK_Static_Expression
(Low_Bound
(N
))
5498 and then Is_OK_Static_Expression
(High_Bound
(N
));
5499 end Is_OK_Static_Range
;
5501 --------------------------
5502 -- Is_OK_Static_Subtype --
5503 --------------------------
5505 -- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
5506 -- neither bound raises Constraint_Error when evaluated.
5508 function Is_OK_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
5509 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
5510 Anc_Subt
: Entity_Id
;
5513 -- First a quick check on the non static subtype flag. As described
5514 -- in further detail in Einfo, this flag is not decisive in all cases,
5515 -- but if it is set, then the subtype is definitely non-static.
5517 if Is_Non_Static_Subtype
(Typ
) then
5521 -- Then, check if the subtype is strictly static. This takes care of
5522 -- checking for generics and predicates.
5524 if not Is_Static_Subtype
(Typ
) then
5530 if Is_String_Type
(Typ
) then
5532 Ekind
(Typ
) = E_String_Literal_Subtype
5534 (Is_OK_Static_Subtype
(Component_Type
(Typ
))
5535 and then Is_OK_Static_Subtype
(Etype
(First_Index
(Typ
))));
5539 elsif Is_Scalar_Type
(Typ
) then
5540 if Base_T
= Typ
then
5544 Anc_Subt
:= Ancestor_Subtype
(Typ
);
5546 if No
(Anc_Subt
) then
5550 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
5551 -- Get_Type_{Low,High}_Bound.
5553 return Is_OK_Static_Subtype
(Anc_Subt
)
5554 and then Is_OK_Static_Expression
(Type_Low_Bound
(Typ
))
5555 and then Is_OK_Static_Expression
(Type_High_Bound
(Typ
));
5558 -- Types other than string and scalar types are never static
5563 end Is_OK_Static_Subtype
;
5565 ---------------------
5566 -- Is_Out_Of_Range --
5567 ---------------------
5569 function Is_Out_Of_Range
5572 Assume_Valid
: Boolean := False;
5573 Fixed_Int
: Boolean := False;
5574 Int_Real
: Boolean := False) return Boolean
5577 return Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
) =
5579 end Is_Out_Of_Range
;
5581 ----------------------
5582 -- Is_Static_Choice --
5583 ----------------------
5585 function Is_Static_Choice
(Choice
: Node_Id
) return Boolean is
5587 -- Check various possibilities for choice
5589 -- Note: for membership tests, we test more cases than are possible
5590 -- (in particular subtype indication), but it doesn't matter because
5591 -- it just won't occur (we have already done a syntax check).
5593 if Nkind
(Choice
) = N_Others_Choice
then
5596 elsif Nkind
(Choice
) = N_Range
then
5597 return Is_Static_Range
(Choice
);
5599 elsif Nkind
(Choice
) = N_Subtype_Indication
5600 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
5602 return Is_Static_Subtype
(Etype
(Choice
));
5605 return Is_Static_Expression
(Choice
);
5607 end Is_Static_Choice
;
5609 ---------------------------
5610 -- Is_Static_Choice_List --
5611 ---------------------------
5613 function Is_Static_Choice_List
(Choices
: List_Id
) return Boolean is
5617 Choice
:= First
(Choices
);
5618 while Present
(Choice
) loop
5619 if not Is_Static_Choice
(Choice
) then
5627 end Is_Static_Choice_List
;
5629 ---------------------
5630 -- Is_Static_Range --
5631 ---------------------
5633 -- A static range is a range whose bounds are static expressions, or a
5634 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
5635 -- We have already converted range attribute references, so we get the
5636 -- "or" part of this rule without needing a special test.
5638 function Is_Static_Range
(N
: Node_Id
) return Boolean is
5640 return Is_Static_Expression
(Low_Bound
(N
))
5642 Is_Static_Expression
(High_Bound
(N
));
5643 end Is_Static_Range
;
5645 -----------------------
5646 -- Is_Static_Subtype --
5647 -----------------------
5649 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
5651 function Is_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
5652 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
5653 Anc_Subt
: Entity_Id
;
5656 -- First a quick check on the non static subtype flag. As described
5657 -- in further detail in Einfo, this flag is not decisive in all cases,
5658 -- but if it is set, then the subtype is definitely non-static.
5660 if Is_Non_Static_Subtype
(Typ
) then
5664 Anc_Subt
:= Ancestor_Subtype
(Typ
);
5666 if Anc_Subt
= Empty
then
5670 if Is_Generic_Type
(Root_Type
(Base_T
))
5671 or else Is_Generic_Actual_Type
(Base_T
)
5675 -- If there is a dynamic predicate for the type (declared or inherited)
5676 -- the expression is not static.
5678 elsif Has_Dynamic_Predicate_Aspect
(Typ
)
5679 or else (Is_Derived_Type
(Typ
)
5680 and then Has_Aspect
(Typ
, Aspect_Dynamic_Predicate
))
5681 or else (Has_Aspect
(Typ
, Aspect_Predicate
)
5682 and then not Has_Static_Predicate
(Typ
))
5688 elsif Is_String_Type
(Typ
) then
5690 Ekind
(Typ
) = E_String_Literal_Subtype
5691 or else (Is_Static_Subtype
(Component_Type
(Typ
))
5692 and then Is_Static_Subtype
(Etype
(First_Index
(Typ
))));
5696 elsif Is_Scalar_Type
(Typ
) then
5697 if Base_T
= Typ
then
5701 return Is_Static_Subtype
(Anc_Subt
)
5702 and then Is_Static_Expression
(Type_Low_Bound
(Typ
))
5703 and then Is_Static_Expression
(Type_High_Bound
(Typ
));
5706 -- Types other than string and scalar types are never static
5711 end Is_Static_Subtype
;
5713 -------------------------------
5714 -- Is_Statically_Unevaluated --
5715 -------------------------------
5717 function Is_Statically_Unevaluated
(Expr
: Node_Id
) return Boolean is
5718 function Check_Case_Expr_Alternative
5719 (CEA
: Node_Id
) return Match_Result
;
5720 -- We have a message emanating from the Expression of a case expression
5721 -- alternative. We examine this alternative, as follows:
5723 -- If the selecting expression of the parent case is non-static, or
5724 -- if any of the discrete choices of the given case alternative are
5725 -- non-static or raise Constraint_Error, return Non_Static.
5727 -- Otherwise check if the selecting expression matches any of the given
5728 -- discrete choices. If so, the alternative is executed and we return
5729 -- Match, otherwise, the alternative can never be executed, and so we
5732 ---------------------------------
5733 -- Check_Case_Expr_Alternative --
5734 ---------------------------------
5736 function Check_Case_Expr_Alternative
5737 (CEA
: Node_Id
) return Match_Result
5739 Case_Exp
: constant Node_Id
:= Parent
(CEA
);
5744 pragma Assert
(Nkind
(Case_Exp
) = N_Case_Expression
);
5746 -- Check that selecting expression is static
5748 if not Is_OK_Static_Expression
(Expression
(Case_Exp
)) then
5752 if not Is_OK_Static_Choice_List
(Discrete_Choices
(CEA
)) then
5756 -- All choices are now known to be static. Now see if alternative
5757 -- matches one of the choices.
5759 Choice
:= First
(Discrete_Choices
(CEA
));
5760 while Present
(Choice
) loop
5762 -- Check various possibilities for choice, returning Match if we
5763 -- find the selecting value matches any of the choices. Note that
5764 -- we know we are the last choice, so we don't have to keep going.
5766 if Nkind
(Choice
) = N_Others_Choice
then
5768 -- Others choice is a bit annoying, it matches if none of the
5769 -- previous alternatives matches (note that we know we are the
5770 -- last alternative in this case, so we can just go backwards
5771 -- from us to see if any previous one matches).
5773 Prev_CEA
:= Prev
(CEA
);
5774 while Present
(Prev_CEA
) loop
5775 if Check_Case_Expr_Alternative
(Prev_CEA
) = Match
then
5784 -- Else we have a normal static choice
5786 elsif Choice_Matches
(Expression
(Case_Exp
), Choice
) = Match
then
5790 -- If we fall through, it means that the discrete choice did not
5791 -- match the selecting expression, so continue.
5796 -- If we get through that loop then all choices were static, and none
5797 -- of them matched the selecting expression. So return No_Match.
5800 end Check_Case_Expr_Alternative
;
5808 -- Start of processing for Is_Statically_Unevaluated
5811 -- The (32.x) references here are from RM section 4.9
5813 -- (32.1) An expression is statically unevaluated if it is part of ...
5815 -- This means we have to climb the tree looking for one of the cases
5822 -- (32.2) The right operand of a static short-circuit control form
5823 -- whose value is determined by its left operand.
5825 -- AND THEN with False as left operand
5827 if Nkind
(P
) = N_And_Then
5828 and then Compile_Time_Known_Value
(Left_Opnd
(P
))
5829 and then Is_False
(Expr_Value
(Left_Opnd
(P
)))
5833 -- OR ELSE with True as left operand
5835 elsif Nkind
(P
) = N_Or_Else
5836 and then Compile_Time_Known_Value
(Left_Opnd
(P
))
5837 and then Is_True
(Expr_Value
(Left_Opnd
(P
)))
5841 -- (32.3) A dependent_expression of an if_expression whose associated
5842 -- condition is static and equals False.
5844 elsif Nkind
(P
) = N_If_Expression
then
5846 Cond
: constant Node_Id
:= First
(Expressions
(P
));
5847 Texp
: constant Node_Id
:= Next
(Cond
);
5848 Fexp
: constant Node_Id
:= Next
(Texp
);
5851 if Compile_Time_Known_Value
(Cond
) then
5853 -- Condition is True and we are in the right operand
5855 if Is_True
(Expr_Value
(Cond
)) and then OldP
= Fexp
then
5858 -- Condition is False and we are in the left operand
5860 elsif Is_False
(Expr_Value
(Cond
)) and then OldP
= Texp
then
5866 -- (32.4) A condition or dependent_expression of an if_expression
5867 -- where the condition corresponding to at least one preceding
5868 -- dependent_expression of the if_expression is static and equals
5871 -- This refers to cases like
5873 -- (if True then 1 elsif 1/0=2 then 2 else 3)
5875 -- But we expand elsif's out anyway, so the above looks like:
5877 -- (if True then 1 else (if 1/0=2 then 2 else 3))
5879 -- So for us this is caught by the above check for the 32.3 case.
5881 -- (32.5) A dependent_expression of a case_expression whose
5882 -- selecting_expression is static and whose value is not covered
5883 -- by the corresponding discrete_choice_list.
5885 elsif Nkind
(P
) = N_Case_Expression_Alternative
then
5887 -- First, we have to be in the expression to suppress messages.
5888 -- If we are within one of the choices, we want the message.
5890 if OldP
= Expression
(P
) then
5892 -- Statically unevaluated if alternative does not match
5894 if Check_Case_Expr_Alternative
(P
) = No_Match
then
5899 -- (32.6) A choice_expression (or a simple_expression of a range
5900 -- that occurs as a membership_choice of a membership_choice_list)
5901 -- of a static membership test that is preceded in the enclosing
5902 -- membership_choice_list by another item whose individual
5903 -- membership test (see (RM 4.5.2)) statically yields True.
5905 elsif Nkind
(P
) in N_Membership_Test
then
5907 -- Only possibly unevaluated if simple expression is static
5909 if not Is_OK_Static_Expression
(Left_Opnd
(P
)) then
5912 -- All members of the choice list must be static
5914 elsif (Present
(Right_Opnd
(P
))
5915 and then not Is_OK_Static_Choice
(Right_Opnd
(P
)))
5916 or else (Present
(Alternatives
(P
))
5918 not Is_OK_Static_Choice_List
(Alternatives
(P
)))
5922 -- If expression is the one and only alternative, then it is
5923 -- definitely not statically unevaluated, so we only have to
5924 -- test the case where there are alternatives present.
5926 elsif Present
(Alternatives
(P
)) then
5928 -- Look for previous matching Choice
5930 Choice
:= First
(Alternatives
(P
));
5931 while Present
(Choice
) loop
5933 -- If we reached us and no previous choices matched, this
5934 -- is not the case where we are statically unevaluated.
5936 exit when OldP
= Choice
;
5938 -- If a previous choice matches, then that is the case where
5939 -- we know our choice is statically unevaluated.
5941 if Choice_Matches
(Left_Opnd
(P
), Choice
) = Match
then
5948 -- If we fall through the loop, we were not one of the choices,
5949 -- we must have been the expression, so that is not covered by
5950 -- this rule, and we keep going.
5956 -- OK, not statically unevaluated at this level, see if we should
5957 -- keep climbing to look for a higher level reason.
5959 -- Special case for component association in aggregates, where
5960 -- we want to keep climbing up to the parent aggregate.
5962 if Nkind
(P
) = N_Component_Association
5963 and then Nkind
(Parent
(P
)) = N_Aggregate
5967 -- All done if not still within subexpression
5970 exit when Nkind
(P
) not in N_Subexpr
;
5974 -- If we fall through the loop, not one of the cases covered!
5977 end Is_Statically_Unevaluated
;
5979 --------------------
5980 -- Machine_Number --
5981 --------------------
5983 -- Historical note: RM 4.9(38) originally specified biased rounding but
5984 -- this has been modified by AI-268 to prevent confusing differences in
5985 -- rounding between static and nonstatic expressions. This AI specifies
5986 -- that the effect of such rounding is implementation-dependent instead,
5987 -- and in GNAT we round to nearest even to match the run-time behavior.
5988 -- Note that this applies to floating-point literals, not fixed-point
5989 -- ones, even though their representation is also a universal real.
5991 function Machine_Number
5994 N
: Node_Id
) return Ureal
5997 return Machine
(Typ
, Val
, Round_Even
, N
);
6000 --------------------
6001 -- Not_Null_Range --
6002 --------------------
6004 function Not_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
6006 if Compile_Time_Known_Value
(Lo
)
6007 and then Compile_Time_Known_Value
(Hi
)
6010 Typ
: Entity_Id
:= Etype
(Lo
);
6012 -- When called from the frontend, as part of the analysis of
6013 -- potentially static expressions, Typ will be the full view of a
6014 -- type with all the info needed to answer this query. When called
6015 -- from the backend, for example to know whether a range of a loop
6016 -- is null, Typ might be a private type and we need to explicitly
6017 -- switch to its corresponding full view to access the same info.
6019 if Is_Incomplete_Or_Private_Type
(Typ
)
6020 and then Present
(Full_View
(Typ
))
6022 Typ
:= Full_View
(Typ
);
6025 if Is_Discrete_Type
(Typ
) then
6026 return Expr_Value
(Lo
) <= Expr_Value
(Hi
);
6027 else pragma Assert
(Is_Real_Type
(Typ
));
6028 return Expr_Value_R
(Lo
) <= Expr_Value_R
(Hi
);
6041 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean is
6043 -- We allow a maximum of 500,000 bits which seems a reasonable limit
6045 if Bits
< 500_000
then
6048 -- Error if this maximum is exceeded
6051 Error_Msg_N
("static value too large, capacity exceeded", N
);
6060 procedure Out_Of_Range
(N
: Node_Id
) is
6062 -- If the FE conjures up an expression that would normally be
6063 -- an illegal static expression (e.g., an integer literal with
6064 -- a value outside of its base subtype), we don't want to
6065 -- flag it as illegal; we only want a warning in such cases.
6067 function Force_Warning
return Boolean is
6068 (if Comes_From_Source
(Original_Node
(N
)) then False
6069 elsif Nkind
(Original_Node
(N
)) = N_Type_Conversion
then True
6070 else Is_Null_Array_Aggregate_High_Bound
(N
));
6072 -- If we have the static expression case, then this is an illegality
6073 -- in Ada 95 mode, except that in an instance, we never generate an
6074 -- error (if the error is legitimate, it was already diagnosed in the
6077 if Is_Static_Expression
(N
)
6078 and then not In_Instance
6079 and then not In_Inlined_Body
6080 and then Ada_Version
>= Ada_95
6082 -- No message if we are statically unevaluated
6084 if Is_Statically_Unevaluated
(N
) then
6087 -- The expression to compute the length of a packed array is attached
6088 -- to the array type itself, and deserves a separate message.
6090 elsif Nkind
(Parent
(N
)) = N_Defining_Identifier
6091 and then Is_Array_Type
(Parent
(N
))
6092 and then Present
(Packed_Array_Impl_Type
(Parent
(N
)))
6093 and then Present
(First_Rep_Item
(Parent
(N
)))
6096 ("length of packed array must not exceed Integer''Last",
6097 First_Rep_Item
(Parent
(N
)));
6098 Rewrite
(N
, Make_Integer_Literal
(Sloc
(N
), Uint_1
));
6100 -- All cases except the special array case.
6101 -- No message if we are dealing with System.Priority values in
6102 -- CodePeer mode where the target runtime may have more priorities.
6104 elsif not CodePeer_Mode
6105 or else not Is_RTE
(Etype
(N
), RE_Priority
)
6107 -- Determine if the out-of-range violation constitutes a warning
6108 -- or an error based on context, according to RM 4.9 (34/3).
6110 if Force_Warning
then
6111 Apply_Compile_Time_Constraint_Error
6112 (N
, "value not in range of}??", CE_Range_Check_Failed
);
6114 Apply_Compile_Time_Constraint_Error
6115 (N
, "value not in range of}", CE_Range_Check_Failed
);
6119 -- Here we generate a warning for the Ada 83 case, or when we are in an
6120 -- instance, or when we have a non-static expression case.
6123 Apply_Compile_Time_Constraint_Error
6124 (N
, "value not in range of}??", CE_Range_Check_Failed
);
6128 ---------------------------
6129 -- Predicates_Compatible --
6130 ---------------------------
6132 function Predicates_Compatible
(T1
, T2
: Entity_Id
) return Boolean is
6134 function T2_Rep_Item_Applies_To_T1
(Nam
: Name_Id
) return Boolean;
6135 -- Return True if the rep item for Nam is either absent on T2 or also
6138 -------------------------------
6139 -- T2_Rep_Item_Applies_To_T1 --
6140 -------------------------------
6142 function T2_Rep_Item_Applies_To_T1
(Nam
: Name_Id
) return Boolean is
6143 Rep_Item
: constant Node_Id
:= Get_Rep_Item
(T2
, Nam
);
6146 return No
(Rep_Item
) or else Get_Rep_Item
(T1
, Nam
) = Rep_Item
;
6147 end T2_Rep_Item_Applies_To_T1
;
6149 -- Start of processing for Predicates_Compatible
6152 if Ada_Version
< Ada_2012
then
6155 -- If T2 has no predicates, there is no compatibility issue
6157 elsif not Has_Predicates
(T2
) then
6160 -- T2 has predicates, if T1 has none then we defer to the static check
6162 elsif not Has_Predicates
(T1
) then
6165 -- Both T2 and T1 have predicates, check that all predicates that apply
6166 -- to T2 apply also to T1 (RM 4.9.1(9/3)).
6168 elsif T2_Rep_Item_Applies_To_T1
(Name_Static_Predicate
)
6169 and then T2_Rep_Item_Applies_To_T1
(Name_Dynamic_Predicate
)
6170 and then T2_Rep_Item_Applies_To_T1
(Name_Predicate
)
6175 -- Implement the static check prescribed by RM 4.9.1(10/3)
6177 if Is_Static_Subtype
(T1
) and then Is_Static_Subtype
(T2
) then
6178 -- We just need to query Interval_Lists for discrete types
6180 if Is_Discrete_Type
(T1
) and then Is_Discrete_Type
(T2
) then
6182 Interval_List1
: constant Interval_Lists
.Discrete_Interval_List
6183 := Interval_Lists
.Type_Intervals
(T1
);
6184 Interval_List2
: constant Interval_Lists
.Discrete_Interval_List
6185 := Interval_Lists
.Type_Intervals
(T2
);
6187 return Interval_Lists
.Is_Subset
(Interval_List1
, Interval_List2
)
6188 and then not (Has_Predicates
(T1
)
6189 and then not Predicate_Checks_Suppressed
(T2
)
6190 and then Predicate_Checks_Suppressed
(T1
));
6194 -- ??? Need to implement Interval_Lists for real types
6199 -- If either subtype is not static, the predicates are not compatible
6204 end Predicates_Compatible
;
6206 ----------------------
6207 -- Predicates_Match --
6208 ----------------------
6210 function Predicates_Match
(T1
, T2
: Entity_Id
) return Boolean is
6212 function Have_Same_Rep_Item
(Nam
: Name_Id
) return Boolean;
6213 -- Return True if T1 and T2 have the same rep item for Nam
6215 ------------------------
6216 -- Have_Same_Rep_Item --
6217 ------------------------
6219 function Have_Same_Rep_Item
(Nam
: Name_Id
) return Boolean is
6221 return Get_Rep_Item
(T1
, Nam
) = Get_Rep_Item
(T2
, Nam
);
6222 end Have_Same_Rep_Item
;
6224 -- Start of processing for Predicates_Match
6227 if Ada_Version
< Ada_2012
then
6230 -- If T2 has no predicates, match if and only if T1 has none
6232 elsif not Has_Predicates
(T2
) then
6233 return not Has_Predicates
(T1
);
6235 -- T2 has predicates, no match if T1 has none
6237 elsif not Has_Predicates
(T1
) then
6240 -- Both T2 and T1 have predicates, check that they all come
6241 -- from the same declarations.
6244 return Have_Same_Rep_Item
(Name_Static_Predicate
)
6245 and then Have_Same_Rep_Item
(Name_Dynamic_Predicate
)
6246 and then Have_Same_Rep_Item
(Name_Predicate
);
6248 end Predicates_Match
;
6250 ---------------------------------------------
6251 -- Real_Or_String_Static_Predicate_Matches --
6252 ---------------------------------------------
6254 function Real_Or_String_Static_Predicate_Matches
6256 Typ
: Entity_Id
) return Boolean
6258 Expr
: constant Node_Id
:= Static_Real_Or_String_Predicate
(Typ
);
6259 -- The predicate expression from the type
6261 Pfun
: constant Entity_Id
:= Predicate_Function
(Typ
);
6262 -- The entity for the predicate function
6264 Ent_Name
: constant Name_Id
:= Chars
(First_Formal
(Pfun
));
6265 -- The name of the formal of the predicate function. Occurrences of the
6266 -- type name in Expr have been rewritten as references to this formal,
6267 -- and it has a unique name, so we can identify references by this name.
6270 -- Copy of the predicate function tree
6272 function Process
(N
: Node_Id
) return Traverse_Result
;
6273 -- Function used to process nodes during the traversal in which we will
6274 -- find occurrences of the entity name, and replace such occurrences
6275 -- by a real literal with the value to be tested.
6277 procedure Traverse
is new Traverse_Proc
(Process
);
6278 -- The actual traversal procedure
6284 function Process
(N
: Node_Id
) return Traverse_Result
is
6286 if Nkind
(N
) = N_Identifier
and then Chars
(N
) = Ent_Name
then
6288 Nod
: constant Node_Id
:= New_Copy
(Val
);
6290 Set_Sloc
(Nod
, Sloc
(N
));
6295 -- The predicate function may contain string-comparison operations
6296 -- that have been converted into calls to run-time array-comparison
6297 -- routines. To evaluate the predicate statically, we recover the
6298 -- original comparison operation and replace the occurrence of the
6299 -- formal by the static string value. The actuals of the generated
6300 -- call are of the form X'Address.
6302 elsif Nkind
(N
) in N_Op_Compare
6303 and then Nkind
(Left_Opnd
(N
)) = N_Function_Call
6306 C
: constant Node_Id
:= Left_Opnd
(N
);
6307 F
: constant Node_Id
:= First
(Parameter_Associations
(C
));
6308 L
: constant Node_Id
:= Prefix
(F
);
6309 R
: constant Node_Id
:= Prefix
(Next
(F
));
6312 -- If an operand is an entity name, it is the formal of the
6313 -- predicate function, so replace it with the string value.
6314 -- It may be either operand in the call. The other operand
6315 -- is a static string from the original predicate.
6317 if Is_Entity_Name
(L
) then
6318 Rewrite
(Left_Opnd
(N
), New_Copy
(Val
));
6319 Rewrite
(Right_Opnd
(N
), New_Copy
(R
));
6322 Rewrite
(Left_Opnd
(N
), New_Copy
(L
));
6323 Rewrite
(Right_Opnd
(N
), New_Copy
(Val
));
6334 -- Start of processing for Real_Or_String_Static_Predicate_Matches
6337 -- First deal with special case of inherited predicate, where the
6338 -- predicate expression looks like:
6340 -- xxPredicate (typ (Ent)) and then Expr
6342 -- where Expr is the predicate expression for this level, and the
6343 -- left operand is the call to evaluate the inherited predicate.
6345 if Nkind
(Expr
) = N_And_Then
6346 and then Nkind
(Left_Opnd
(Expr
)) = N_Function_Call
6347 and then Is_Predicate_Function
(Entity
(Name
(Left_Opnd
(Expr
))))
6349 -- OK we have the inherited case, so make a call to evaluate the
6350 -- inherited predicate. If that fails, so do we!
6353 Real_Or_String_Static_Predicate_Matches
6355 Typ
=> Etype
(First_Formal
(Entity
(Name
(Left_Opnd
(Expr
))))))
6360 -- Use the right operand for the continued processing
6362 Copy
:= Copy_Separate_Tree
(Right_Opnd
(Expr
));
6364 -- Case where call to predicate function appears on its own (this means
6365 -- that the predicate at this level is just inherited from the parent).
6367 elsif Nkind
(Expr
) = N_Function_Call
then
6369 Typ
: constant Entity_Id
:=
6370 Etype
(First_Formal
(Entity
(Name
(Expr
))));
6373 -- If the inherited predicate is dynamic, just ignore it. We can't
6374 -- go trying to evaluate a dynamic predicate as a static one!
6376 if Has_Dynamic_Predicate_Aspect
(Typ
) then
6379 -- Otherwise inherited predicate is static, check for match
6382 return Real_Or_String_Static_Predicate_Matches
(Val
, Typ
);
6386 -- If not just an inherited predicate, copy whole expression
6389 Copy
:= Copy_Separate_Tree
(Expr
);
6392 -- Now we replace occurrences of the entity by the value
6396 -- And analyze the resulting static expression to see if it is True
6398 Analyze_And_Resolve
(Copy
, Standard_Boolean
);
6399 return Is_True
(Expr_Value
(Copy
));
6400 end Real_Or_String_Static_Predicate_Matches
;
6402 -------------------------
6403 -- Rewrite_In_Raise_CE --
6404 -------------------------
6406 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
) is
6407 Stat
: constant Boolean := Is_Static_Expression
(N
);
6408 Typ
: constant Entity_Id
:= Etype
(N
);
6411 -- If we want to raise CE in the condition of a N_Raise_CE node, we
6412 -- can just clear the condition if the reason is appropriate. We do
6413 -- not do this operation if the parent has a reason other than range
6414 -- check failed, because otherwise we would change the reason.
6416 if Present
(Parent
(N
))
6417 and then Nkind
(Parent
(N
)) = N_Raise_Constraint_Error
6418 and then Reason
(Parent
(N
)) =
6419 UI_From_Int
(RT_Exception_Code
'Pos (CE_Range_Check_Failed
))
6421 Set_Condition
(Parent
(N
), Empty
);
6423 -- Else build an explicit N_Raise_CE
6426 if Nkind
(Exp
) = N_Raise_Constraint_Error
then
6428 Make_Raise_Constraint_Error
(Sloc
(Exp
),
6429 Reason
=> Reason
(Exp
)));
6432 Make_Raise_Constraint_Error
(Sloc
(Exp
),
6433 Reason
=> CE_Range_Check_Failed
));
6436 Set_Raises_Constraint_Error
(N
);
6440 -- Set proper flags in result
6442 Set_Raises_Constraint_Error
(N
, True);
6443 Set_Is_Static_Expression
(N
, Stat
);
6444 end Rewrite_In_Raise_CE
;
6446 ------------------------------------------------
6447 -- Set_Checking_Potentially_Static_Expression --
6448 ------------------------------------------------
6450 procedure Set_Checking_Potentially_Static_Expression
(Value
: Boolean) is
6452 -- Verify that we only start/stop checking for a potentially static
6453 -- expression and do not start or stop it twice in a row.
6455 pragma Assert
(Checking_For_Potentially_Static_Expression
/= Value
);
6457 Checking_For_Potentially_Static_Expression
:= Value
;
6458 end Set_Checking_Potentially_Static_Expression
;
6460 ---------------------
6461 -- String_Type_Len --
6462 ---------------------
6464 function String_Type_Len
(Stype
: Entity_Id
) return Uint
is
6465 NT
: constant Entity_Id
:= Etype
(First_Index
(Stype
));
6469 if Is_OK_Static_Subtype
(NT
) then
6472 T
:= Base_Type
(NT
);
6475 return Expr_Value
(Type_High_Bound
(T
)) -
6476 Expr_Value
(Type_Low_Bound
(T
)) + 1;
6477 end String_Type_Len
;
6479 ------------------------------------
6480 -- Subtypes_Statically_Compatible --
6481 ------------------------------------
6483 function Subtypes_Statically_Compatible
6486 Formal_Derived_Matching
: Boolean := False) return Boolean
6489 -- A type is always statically compatible with itself
6494 -- Not compatible if predicates are not compatible
6496 elsif not Predicates_Compatible
(T1
, T2
) then
6501 elsif Is_Scalar_Type
(T1
) then
6503 -- Definitely compatible if we match
6505 if Subtypes_Statically_Match
(T1
, T2
) then
6508 -- A scalar subtype S1 is compatible with S2 if their bounds
6509 -- are static and compatible, even if S1 has dynamic predicates
6510 -- and is thus non-static. Predicate compatibility has been
6513 elsif not Is_Static_Range
(Scalar_Range
(T1
))
6514 or else not Is_Static_Range
(Scalar_Range
(T2
))
6518 -- Base types must match, but we don't check that (should we???) but
6519 -- we do at least check that both types are real, or both types are
6522 elsif Is_Real_Type
(T1
) /= Is_Real_Type
(T2
) then
6525 -- Here we check the bounds
6529 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
6530 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
6531 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
6532 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
6535 if Is_Real_Type
(T1
) then
6537 Expr_Value_R
(LB1
) > Expr_Value_R
(HB1
)
6539 (Expr_Value_R
(LB2
) <= Expr_Value_R
(LB1
)
6540 and then Expr_Value_R
(HB1
) <= Expr_Value_R
(HB2
));
6544 Expr_Value
(LB1
) > Expr_Value
(HB1
)
6546 (Expr_Value
(LB2
) <= Expr_Value
(LB1
)
6547 and then Expr_Value
(HB1
) <= Expr_Value
(HB2
));
6554 elsif Is_Access_Type
(T1
) then
6556 (not Is_Constrained
(T2
)
6557 or else Subtypes_Statically_Match
6558 (Designated_Type
(T1
), Designated_Type
(T2
)))
6559 and then not (Can_Never_Be_Null
(T2
)
6560 and then not Can_Never_Be_Null
(T1
));
6562 -- Private types without discriminants can be handled specially.
6563 -- Predicate matching has been checked above.
6565 elsif Is_Private_Type
(T1
)
6566 and then not Has_Discriminants
(T1
)
6568 return not Has_Discriminants
(T2
);
6574 (Is_Composite_Type
(T1
) and then not Is_Constrained
(T2
))
6575 or else Subtypes_Statically_Match
6576 (T1
, T2
, Formal_Derived_Matching
);
6578 end Subtypes_Statically_Compatible
;
6580 -------------------------------
6581 -- Subtypes_Statically_Match --
6582 -------------------------------
6584 -- Subtypes statically match if they have statically matching constraints
6585 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
6586 -- they are the same identical constraint, or if they are static and the
6587 -- values match (RM 4.9.1(1)).
6589 -- In addition, in GNAT, the object size (Esize) values of the types must
6590 -- match if they are set (unless checking an actual for a formal derived
6591 -- type). The use of 'Object_Size can cause this to be false even if the
6592 -- types would otherwise match in the Ada 95 RM sense, but this deviation
6593 -- is adopted by AI12-059 which introduces Object_Size in Ada 2022.
6595 function Subtypes_Statically_Match
6598 Formal_Derived_Matching
: Boolean := False) return Boolean
6601 -- A type always statically matches itself
6606 -- No match if sizes different (from use of 'Object_Size). This test
6607 -- is excluded if Formal_Derived_Matching is True, as the base types
6608 -- can be different in that case and typically have different sizes.
6610 elsif not Formal_Derived_Matching
6611 and then Known_Static_Esize
(T1
)
6612 and then Known_Static_Esize
(T2
)
6613 and then Esize
(T1
) /= Esize
(T2
)
6617 -- No match if predicates do not match
6619 elsif not Predicates_Match
(T1
, T2
) then
6624 elsif Is_Scalar_Type
(T1
) then
6626 -- Base types must be the same
6628 if Base_Type
(T1
) /= Base_Type
(T2
) then
6632 -- A constrained numeric subtype never matches an unconstrained
6633 -- subtype, i.e. both types must be constrained or unconstrained.
6635 -- To understand the requirement for this test, see RM 4.9.1(1).
6636 -- As is made clear in RM 3.5.4(11), type Integer, for example is
6637 -- a constrained subtype with constraint bounds matching the bounds
6638 -- of its corresponding unconstrained base type. In this situation,
6639 -- Integer and Integer'Base do not statically match, even though
6640 -- they have the same bounds.
6642 -- We only apply this test to types in Standard and types that appear
6643 -- in user programs. That way, we do not have to be too careful about
6644 -- setting Is_Constrained right for Itypes.
6646 if Is_Numeric_Type
(T1
)
6647 and then Is_Constrained
(T1
) /= Is_Constrained
(T2
)
6648 and then (Scope
(T1
) = Standard_Standard
6649 or else Comes_From_Source
(T1
))
6650 and then (Scope
(T2
) = Standard_Standard
6651 or else Comes_From_Source
(T2
))
6655 -- A generic scalar type does not statically match its base type
6656 -- (AI-311). In this case we make sure that the formals, which are
6657 -- first subtypes of their bases, are constrained.
6659 elsif Is_Generic_Type
(T1
)
6660 and then Is_Generic_Type
(T2
)
6661 and then Is_Constrained
(T1
) /= Is_Constrained
(T2
)
6666 -- If there was an error in either range, then just assume the types
6667 -- statically match to avoid further junk errors.
6669 if No
(Scalar_Range
(T1
)) or else No
(Scalar_Range
(T2
))
6670 or else Error_Posted
(Scalar_Range
(T1
))
6671 or else Error_Posted
(Scalar_Range
(T2
))
6676 -- Otherwise both types have bounds that can be compared
6679 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
6680 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
6681 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
6682 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
6685 -- If the bounds are the same tree node, then match (common case)
6687 if LB1
= LB2
and then HB1
= HB2
then
6690 -- Otherwise bounds must be static and identical value
6693 if not Is_OK_Static_Subtype
(T1
)
6695 not Is_OK_Static_Subtype
(T2
)
6699 elsif Is_Real_Type
(T1
) then
6701 Expr_Value_R
(LB1
) = Expr_Value_R
(LB2
)
6703 Expr_Value_R
(HB1
) = Expr_Value_R
(HB2
);
6707 Expr_Value
(LB1
) = Expr_Value
(LB2
)
6709 Expr_Value
(HB1
) = Expr_Value
(HB2
);
6714 -- Type with discriminants
6716 elsif Has_Discriminants
(T1
) or else Has_Discriminants
(T2
) then
6718 -- Handle derivations of private subtypes. For example S1 statically
6719 -- matches the full view of T1 in the following example:
6721 -- type T1(<>) is new Root with private;
6722 -- subtype S1 is new T1;
6723 -- overriding proc P1 (P : S1);
6725 -- type T1 (D : Disc) is new Root with ...
6727 if Ekind
(T2
) = E_Record_Subtype_With_Private
6728 and then not Has_Discriminants
(T2
)
6729 and then Partial_View_Has_Unknown_Discr
(T1
)
6730 and then Etype
(T2
) = T1
6734 elsif Ekind
(T1
) = E_Record_Subtype_With_Private
6735 and then not Has_Discriminants
(T1
)
6736 and then Partial_View_Has_Unknown_Discr
(T2
)
6737 and then Etype
(T1
) = T2
6741 -- Because of view exchanges in multiple instantiations, conformance
6742 -- checking might try to match a partial view of a type with no
6743 -- discriminants with a full view that has defaulted discriminants.
6744 -- In such a case, use the discriminant constraint of the full view,
6745 -- which must exist because we know that the two subtypes have the
6748 elsif Has_Discriminants
(T1
) /= Has_Discriminants
(T2
) then
6750 if Is_Private_Type
(T2
)
6751 and then Present
(Full_View
(T2
))
6752 and then Has_Discriminants
(Full_View
(T2
))
6754 return Subtypes_Statically_Match
(T1
, Full_View
(T2
));
6756 elsif Is_Private_Type
(T1
)
6757 and then Present
(Full_View
(T1
))
6758 and then Has_Discriminants
(Full_View
(T1
))
6760 return Subtypes_Statically_Match
(Full_View
(T1
), T2
);
6772 function Original_Discriminant_Constraint
6773 (Typ
: Entity_Id
) return Elist_Id
;
6774 -- Returns Typ's discriminant constraint, or if the constraint
6775 -- is inherited from an ancestor type, then climbs the parent
6776 -- types to locate and return the constraint farthest up the
6777 -- parent chain that Typ's constraint is ultimately inherited
6778 -- from (stopping before a parent that doesn't impose a constraint
6779 -- or a parent that has new discriminants). This ensures a proper
6780 -- result from the equality comparison of Elist_Ids below (as
6781 -- otherwise, derived types that inherit constraints may appear
6782 -- to be unequal, because each level of derivation can have its
6783 -- own copy of the constraint).
6785 function Original_Discriminant_Constraint
6786 (Typ
: Entity_Id
) return Elist_Id
6789 if not Has_Discriminants
(Typ
) then
6792 -- If Typ is not a derived type, then directly return the
6795 elsif not Is_Derived_Type
(Typ
) then
6796 return Discriminant_Constraint
(Typ
);
6798 -- If the parent type doesn't have discriminants, doesn't
6799 -- have a constraint, or has new discriminants, then stop
6800 -- and return Typ's constraint.
6802 elsif not Has_Discriminants
(Etype
(Typ
))
6804 -- No constraint on the parent type
6806 or else not Present
(Discriminant_Constraint
(Etype
(Typ
)))
6807 or else Is_Empty_Elmt_List
6808 (Discriminant_Constraint
(Etype
(Typ
)))
6810 -- The parent type defines new discriminants
6813 (Is_Base_Type
(Etype
(Typ
))
6814 and then Present
(Discriminant_Specifications
6815 (Parent
(Etype
(Typ
)))))
6817 return Discriminant_Constraint
(Typ
);
6819 -- Otherwise, make a recursive call on the parent type
6822 return Original_Discriminant_Constraint
(Etype
(Typ
));
6824 end Original_Discriminant_Constraint
;
6828 DL1
: constant Elist_Id
:= Original_Discriminant_Constraint
(T1
);
6829 DL2
: constant Elist_Id
:= Original_Discriminant_Constraint
(T2
);
6837 elsif Is_Constrained
(T1
) /= Is_Constrained
(T2
) then
6841 -- Now loop through the discriminant constraints
6843 -- Note: the guard here seems necessary, since it is possible at
6844 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
6846 if Present
(DL1
) and then Present
(DL2
) then
6847 DA1
:= First_Elmt
(DL1
);
6848 DA2
:= First_Elmt
(DL2
);
6849 while Present
(DA1
) loop
6851 Expr1
: constant Node_Id
:= Node
(DA1
);
6852 Expr2
: constant Node_Id
:= Node
(DA2
);
6855 if not Is_OK_Static_Expression
(Expr1
)
6856 or else not Is_OK_Static_Expression
(Expr2
)
6860 -- If either expression raised a Constraint_Error,
6861 -- consider the expressions as matching, since this
6862 -- helps to prevent cascading errors.
6864 elsif Raises_Constraint_Error
(Expr1
)
6865 or else Raises_Constraint_Error
(Expr2
)
6869 elsif Expr_Value
(Expr1
) /= Expr_Value
(Expr2
) then
6882 -- A definite type does not match an indefinite or classwide type.
6883 -- However, a generic type with unknown discriminants may be
6884 -- instantiated with a type with no discriminants, and conformance
6885 -- checking on an inherited operation may compare the actual with the
6886 -- subtype that renames it in the instance.
6888 elsif Has_Unknown_Discriminants
(T1
) /= Has_Unknown_Discriminants
(T2
)
6891 Is_Generic_Actual_Type
(T1
) or else Is_Generic_Actual_Type
(T2
);
6895 elsif Is_Array_Type
(T1
) then
6897 -- If either subtype is unconstrained then both must be, and if both
6898 -- are unconstrained then no further checking is needed.
6900 if not Is_Constrained
(T1
) or else not Is_Constrained
(T2
) then
6901 return not (Is_Constrained
(T1
) or else Is_Constrained
(T2
));
6904 -- Both subtypes are constrained, so check that the index subtypes
6905 -- statically match.
6908 Index1
: Node_Id
:= First_Index
(T1
);
6909 Index2
: Node_Id
:= First_Index
(T2
);
6912 while Present
(Index1
) loop
6914 Subtypes_Statically_Match
(Etype
(Index1
), Etype
(Index2
))
6919 Next_Index
(Index1
);
6920 Next_Index
(Index2
);
6926 elsif Is_Access_Type
(T1
) then
6927 if Can_Never_Be_Null
(T1
) /= Can_Never_Be_Null
(T2
) then
6930 elsif Ekind
(T1
) in E_Access_Subprogram_Type
6931 | E_Anonymous_Access_Subprogram_Type
6935 (Designated_Type
(T1
),
6936 Designated_Type
(T2
));
6939 Subtypes_Statically_Match
6940 (Designated_Type
(T1
),
6941 Designated_Type
(T2
))
6942 and then Is_Access_Constant
(T1
) = Is_Access_Constant
(T2
);
6945 -- All other types definitely match
6950 end Subtypes_Statically_Match
;
6956 function Test
(Cond
: Boolean) return Uint
is
6965 ---------------------
6966 -- Test_Comparison --
6967 ---------------------
6969 procedure Test_Comparison
6971 Assume_Valid
: Boolean;
6972 True_Result
: out Boolean;
6973 False_Result
: out Boolean)
6975 Left
: constant Node_Id
:= Left_Opnd
(Op
);
6976 Left_Typ
: constant Entity_Id
:= Etype
(Left
);
6977 Orig_Op
: constant Node_Id
:= Original_Node
(Op
);
6979 procedure Replacement_Warning
(Msg
: String);
6980 -- Emit a warning on a comparison that can be replaced by '='
6982 -------------------------
6983 -- Replacement_Warning --
6984 -------------------------
6986 procedure Replacement_Warning
(Msg
: String) is
6988 if Constant_Condition_Warnings
6989 and then Comes_From_Source
(Orig_Op
)
6990 and then Is_Integer_Type
(Left_Typ
)
6991 and then not Error_Posted
(Op
)
6992 and then not Has_Warnings_Off
(Left_Typ
)
6993 and then not In_Instance
6995 Error_Msg_N
(Msg
, Op
);
6997 end Replacement_Warning
;
7001 Res
: constant Compare_Result
:=
7002 Compile_Time_Compare
(Left
, Right_Opnd
(Op
), Assume_Valid
);
7004 -- Start of processing for Test_Comparison
7007 case N_Op_Compare
(Nkind
(Op
)) is
7009 True_Result
:= Res
= EQ
;
7010 False_Result
:= Res
= LT
or else Res
= GT
or else Res
= NE
;
7013 True_Result
:= Res
in Compare_GE
;
7014 False_Result
:= Res
= LT
;
7016 if Res
= LE
and then Nkind
(Orig_Op
) = N_Op_Ge
then
7018 ("can never be greater than, could replace by ""'=""?c?");
7022 True_Result
:= Res
= GT
;
7023 False_Result
:= Res
in Compare_LE
;
7026 True_Result
:= Res
in Compare_LE
;
7027 False_Result
:= Res
= GT
;
7029 if Res
= GE
and then Nkind
(Orig_Op
) = N_Op_Le
then
7031 ("can never be less than, could replace by ""'=""?c?");
7035 True_Result
:= Res
= LT
;
7036 False_Result
:= Res
in Compare_GE
;
7039 True_Result
:= Res
= NE
or else Res
= GT
or else Res
= LT
;
7040 False_Result
:= Res
= EQ
;
7042 end Test_Comparison
;
7044 ---------------------------------
7045 -- Test_Expression_Is_Foldable --
7046 ---------------------------------
7050 procedure Test_Expression_Is_Foldable
7060 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
7064 -- If operand is Any_Type, just propagate to result and do not
7065 -- try to fold, this prevents cascaded errors.
7067 if Etype
(Op1
) = Any_Type
then
7068 Set_Etype
(N
, Any_Type
);
7071 -- If operand raises Constraint_Error, then replace node N with the
7072 -- raise Constraint_Error node, and we are obviously not foldable.
7073 -- Note that this replacement inherits the Is_Static_Expression flag
7074 -- from the operand.
7076 elsif Raises_Constraint_Error
(Op1
) then
7077 Rewrite_In_Raise_CE
(N
, Op1
);
7080 -- If the operand is not static, then the result is not static, and
7081 -- all we have to do is to check the operand since it is now known
7082 -- to appear in a non-static context.
7084 elsif not Is_Static_Expression
(Op1
) then
7085 Check_Non_Static_Context
(Op1
);
7086 Fold
:= Compile_Time_Known_Value
(Op1
);
7089 -- An expression of a formal modular type is not foldable because
7090 -- the modulus is unknown.
7092 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
7093 and then Is_Generic_Type
(Etype
(Op1
))
7095 Check_Non_Static_Context
(Op1
);
7098 -- Here we have the case of an operand whose type is OK, which is
7099 -- static, and which does not raise Constraint_Error, we can fold.
7102 Set_Is_Static_Expression
(N
);
7106 end Test_Expression_Is_Foldable
;
7110 procedure Test_Expression_Is_Foldable
7116 CRT_Safe
: Boolean := False)
7118 Rstat
: constant Boolean := Is_Static_Expression
(Op1
)
7120 Is_Static_Expression
(Op2
);
7126 -- Inhibit folding if -gnatd.f flag set
7128 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
7132 -- If either operand is Any_Type, just propagate to result and
7133 -- do not try to fold, this prevents cascaded errors.
7135 if Etype
(Op1
) = Any_Type
or else Etype
(Op2
) = Any_Type
then
7136 Set_Etype
(N
, Any_Type
);
7139 -- If left operand raises Constraint_Error, then replace node N with the
7140 -- Raise_Constraint_Error node, and we are obviously not foldable.
7141 -- Is_Static_Expression is set from the two operands in the normal way,
7142 -- and we check the right operand if it is in a non-static context.
7144 elsif Raises_Constraint_Error
(Op1
) then
7146 Check_Non_Static_Context
(Op2
);
7149 Rewrite_In_Raise_CE
(N
, Op1
);
7150 Set_Is_Static_Expression
(N
, Rstat
);
7153 -- Similar processing for the case of the right operand. Note that we
7154 -- don't use this routine for the short-circuit case, so we do not have
7155 -- to worry about that special case here.
7157 elsif Raises_Constraint_Error
(Op2
) then
7159 Check_Non_Static_Context
(Op1
);
7162 Rewrite_In_Raise_CE
(N
, Op2
);
7163 Set_Is_Static_Expression
(N
, Rstat
);
7166 -- Exclude expressions of a generic modular type, as above
7168 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
7169 and then Is_Generic_Type
(Etype
(Op1
))
7171 Check_Non_Static_Context
(Op1
);
7174 -- If result is not static, then check non-static contexts on operands
7175 -- since one of them may be static and the other one may not be static.
7177 elsif not Rstat
then
7178 Check_Non_Static_Context
(Op1
);
7179 Check_Non_Static_Context
(Op2
);
7182 Fold
:= CRT_Safe_Compile_Time_Known_Value
(Op1
)
7183 and then CRT_Safe_Compile_Time_Known_Value
(Op2
);
7185 Fold
:= Compile_Time_Known_Value
(Op1
)
7186 and then Compile_Time_Known_Value
(Op2
);
7190 and then not Is_Modular_Integer_Type
(Etype
(N
))
7195 -- (False and XXX) = (XXX and False) = False
7198 (Compile_Time_Known_Value
(Op1
)
7199 and then Is_False
(Expr_Value
(Op1
))
7200 and then Side_Effect_Free
(Op2
))
7201 or else (Compile_Time_Known_Value
(Op2
)
7202 and then Is_False
(Expr_Value
(Op2
))
7203 and then Side_Effect_Free
(Op1
));
7207 -- (True and XXX) = (XXX and True) = True
7210 (Compile_Time_Known_Value
(Op1
)
7211 and then Is_True
(Expr_Value
(Op1
))
7212 and then Side_Effect_Free
(Op2
))
7213 or else (Compile_Time_Known_Value
(Op2
)
7214 and then Is_True
(Expr_Value
(Op2
))
7215 and then Side_Effect_Free
(Op1
));
7217 when others => null;
7223 -- Else result is static and foldable. Both operands are static, and
7224 -- neither raises Constraint_Error, so we can definitely fold.
7227 Set_Is_Static_Expression
(N
);
7232 end Test_Expression_Is_Foldable
;
7238 function Test_In_Range
7241 Assume_Valid
: Boolean;
7242 Fixed_Int
: Boolean;
7243 Int_Real
: Boolean) return Range_Membership
7248 pragma Warnings
(Off
, Assume_Valid
);
7249 -- For now Assume_Valid is unreferenced since the current implementation
7250 -- always returns Unknown if N is not a compile-time-known value, but we
7251 -- keep the parameter to allow for future enhancements in which we try
7252 -- to get the information in the variable case as well.
7255 -- If an error was posted on expression, then return Unknown, we do not
7256 -- want cascaded errors based on some false analysis of a junk node.
7258 if Error_Posted
(N
) then
7261 -- Expression that raises Constraint_Error is an odd case. We certainly
7262 -- do not want to consider it to be in range. It might make sense to
7263 -- consider it always out of range, but this causes incorrect error
7264 -- messages about static expressions out of range. So we just return
7265 -- Unknown, which is always safe.
7267 elsif Raises_Constraint_Error
(N
) then
7270 -- Universal types have no range limits, so always in range
7272 elsif Is_Universal_Numeric_Type
(Typ
) then
7275 -- Never known if not scalar type. Don't know if this can actually
7276 -- happen, but our spec allows it, so we must check.
7278 elsif not Is_Scalar_Type
(Typ
) then
7281 -- Never known if this is a generic type, since the bounds of generic
7282 -- types are junk. Note that if we only checked for static expressions
7283 -- (instead of compile-time-known values) below, we would not need this
7284 -- check, because values of a generic type can never be static, but they
7285 -- can be known at compile time.
7287 elsif Is_Generic_Type
(Typ
) then
7290 -- Case of a known compile time value, where we can check if it is in
7291 -- the bounds of the given type.
7293 elsif Compile_Time_Known_Value
(N
) then
7295 Lo
: constant Node_Id
:= Type_Low_Bound
(Typ
);
7296 Hi
: constant Node_Id
:= Type_High_Bound
(Typ
);
7297 LB_Known
: constant Boolean := Compile_Time_Known_Value
(Lo
);
7298 HB_Known
: constant Boolean := Compile_Time_Known_Value
(Hi
);
7301 -- Fixed point types should be considered as such only if flag
7302 -- Fixed_Int is set to False.
7304 if Is_Floating_Point_Type
(Typ
)
7305 or else (Is_Fixed_Point_Type
(Typ
) and then not Fixed_Int
)
7308 Valr
:= Expr_Value_R
(N
);
7310 if LB_Known
and HB_Known
then
7311 if Valr
>= Expr_Value_R
(Lo
)
7313 Valr
<= Expr_Value_R
(Hi
)
7317 return Out_Of_Range
;
7320 elsif (LB_Known
and then Valr
< Expr_Value_R
(Lo
))
7322 (HB_Known
and then Valr
> Expr_Value_R
(Hi
))
7324 return Out_Of_Range
;
7331 Val
:= Expr_Value
(N
);
7333 if LB_Known
and HB_Known
then
7334 if Val
>= Expr_Value
(Lo
) and then Val
<= Expr_Value
(Hi
)
7338 return Out_Of_Range
;
7341 elsif (LB_Known
and then Val
< Expr_Value
(Lo
))
7343 (HB_Known
and then Val
> Expr_Value
(Hi
))
7345 return Out_Of_Range
;
7353 -- Here for value not known at compile time. Case of expression subtype
7354 -- is Typ or is a subtype of Typ, and we can assume expression is valid.
7355 -- In this case we know it is in range without knowing its value.
7358 and then (Etype
(N
) = Typ
or else Is_Subtype_Of
(Etype
(N
), Typ
))
7362 -- Another special case. For signed integer types, if the target type
7363 -- has Is_Known_Valid set, and the source type does not have a larger
7364 -- size, then the source value must be in range. We exclude biased
7365 -- types, because they bizarrely can generate out of range values.
7367 elsif Is_Signed_Integer_Type
(Etype
(N
))
7368 and then Is_Known_Valid
(Typ
)
7369 and then Esize
(Etype
(N
)) <= Esize
(Typ
)
7370 and then not Has_Biased_Representation
(Etype
(N
))
7374 -- For all other cases, result is unknown
7385 procedure To_Bits
(U
: Uint
; B
: out Bits
) is
7387 for J
in 0 .. B
'Last loop
7388 B
(J
) := (U
/ (2 ** J
)) mod 2 /= 0;
7392 --------------------
7393 -- Why_Not_Static --
7394 --------------------
7396 procedure Why_Not_Static
(Expr
: Node_Id
) is
7397 N
: constant Node_Id
:= Original_Node
(Expr
);
7398 Typ
: Entity_Id
:= Empty
;
7403 procedure Why_Not_Static_List
(L
: List_Id
);
7404 -- A version that can be called on a list of expressions. Finds all
7405 -- non-static violations in any element of the list.
7407 -------------------------
7408 -- Why_Not_Static_List --
7409 -------------------------
7411 procedure Why_Not_Static_List
(L
: List_Id
) is
7415 while Present
(N
) loop
7419 end Why_Not_Static_List
;
7421 -- Start of processing for Why_Not_Static
7424 -- Ignore call on error or empty node
7426 if No
(Expr
) or else Nkind
(Expr
) = N_Error
then
7430 -- Preprocessing for sub expressions
7432 if Nkind
(Expr
) in N_Subexpr
then
7434 -- Nothing to do if expression is static
7436 if Is_OK_Static_Expression
(Expr
) then
7440 -- Test for Constraint_Error raised
7442 if Raises_Constraint_Error
(Expr
) then
7444 -- Special case membership to find out which piece to flag
7446 if Nkind
(N
) in N_Membership_Test
then
7447 if Raises_Constraint_Error
(Left_Opnd
(N
)) then
7448 Why_Not_Static
(Left_Opnd
(N
));
7451 elsif Present
(Right_Opnd
(N
))
7452 and then Raises_Constraint_Error
(Right_Opnd
(N
))
7454 Why_Not_Static
(Right_Opnd
(N
));
7458 pragma Assert
(Present
(Alternatives
(N
)));
7460 Alt
:= First
(Alternatives
(N
));
7461 while Present
(Alt
) loop
7462 if Raises_Constraint_Error
(Alt
) then
7463 Why_Not_Static
(Alt
);
7471 -- Special case a range to find out which bound to flag
7473 elsif Nkind
(N
) = N_Range
then
7474 if Raises_Constraint_Error
(Low_Bound
(N
)) then
7475 Why_Not_Static
(Low_Bound
(N
));
7478 elsif Raises_Constraint_Error
(High_Bound
(N
)) then
7479 Why_Not_Static
(High_Bound
(N
));
7483 -- Special case attribute to see which part to flag
7485 elsif Nkind
(N
) = N_Attribute_Reference
then
7486 if Raises_Constraint_Error
(Prefix
(N
)) then
7487 Why_Not_Static
(Prefix
(N
));
7491 Exp
:= First
(Expressions
(N
));
7492 while Present
(Exp
) loop
7493 if Raises_Constraint_Error
(Exp
) then
7494 Why_Not_Static
(Exp
);
7501 -- Special case a subtype name
7503 elsif Is_Entity_Name
(Expr
) and then Is_Type
(Entity
(Expr
)) then
7505 ("!& is not a static subtype (RM 4.9(26))", N
, Entity
(Expr
));
7509 -- End of special cases
7512 ("!expression raises exception, cannot be static (RM 4.9(34))",
7517 -- If no type, then something is pretty wrong, so ignore
7519 Typ
:= Etype
(Expr
);
7525 -- Type must be scalar or string type (but allow Bignum, since this
7526 -- is really a scalar type from our point of view in this diagnosis).
7528 if not Is_Scalar_Type
(Typ
)
7529 and then not Is_String_Type
(Typ
)
7530 and then not Is_RTE
(Typ
, RE_Bignum
)
7533 ("!static expression must have scalar or string type " &
7539 -- If we got through those checks, test particular node kind
7545 when N_Expanded_Name
7551 if Is_Named_Number
(E
) then
7554 elsif Ekind
(E
) = E_Constant
then
7556 -- One case we can give a better message is when we have a
7557 -- string literal created by concatenating an aggregate with
7558 -- an others expression.
7560 Entity_Case
: declare
7561 CV
: constant Node_Id
:= Constant_Value
(E
);
7562 CO
: constant Node_Id
:= Original_Node
(CV
);
7564 function Is_Aggregate
(N
: Node_Id
) return Boolean;
7565 -- See if node N came from an others aggregate, if so
7566 -- return True and set Error_Msg_Sloc to aggregate.
7572 function Is_Aggregate
(N
: Node_Id
) return Boolean is
7574 if Nkind
(Original_Node
(N
)) = N_Aggregate
then
7575 Error_Msg_Sloc
:= Sloc
(Original_Node
(N
));
7578 elsif Is_Entity_Name
(N
)
7579 and then Ekind
(Entity
(N
)) = E_Constant
7581 Nkind
(Original_Node
(Constant_Value
(Entity
(N
)))) =
7585 Sloc
(Original_Node
(Constant_Value
(Entity
(N
))));
7593 -- Start of processing for Entity_Case
7596 if Is_Aggregate
(CV
)
7597 or else (Nkind
(CO
) = N_Op_Concat
7598 and then (Is_Aggregate
(Left_Opnd
(CO
))
7600 Is_Aggregate
(Right_Opnd
(CO
))))
7602 Error_Msg_N
("!aggregate (#) is never static", N
);
7604 elsif No
(CV
) or else not Is_Static_Expression
(CV
) then
7606 ("!& is not a static constant (RM 4.9(5))", N
, E
);
7610 elsif Is_Type
(E
) then
7612 ("!& is not a static subtype (RM 4.9(26))", N
, E
);
7616 ("!& is not static constant or named number "
7617 & "(RM 4.9(5))", N
, E
);
7626 if Nkind
(N
) in N_Op_Shift
then
7628 ("!shift functions are never static (RM 4.9(6,18))", N
);
7630 Why_Not_Static
(Left_Opnd
(N
));
7631 Why_Not_Static
(Right_Opnd
(N
));
7637 Why_Not_Static
(Right_Opnd
(N
));
7639 -- Attribute reference
7641 when N_Attribute_Reference
=>
7642 Why_Not_Static_List
(Expressions
(N
));
7644 E
:= Etype
(Prefix
(N
));
7646 if E
= Standard_Void_Type
then
7650 -- Special case non-scalar'Size since this is a common error
7652 if Attribute_Name
(N
) = Name_Size
then
7654 ("!size attribute is only static for static scalar type "
7655 & "(RM 4.9(7,8))", N
);
7659 elsif Is_Array_Type
(E
) then
7660 if Attribute_Name
(N
)
7661 not in Name_First | Name_Last | Name_Length
7664 ("!static array attribute must be Length, First, or Last "
7665 & "(RM 4.9(8))", N
);
7667 -- Since we know the expression is not-static (we already
7668 -- tested for this, must mean array is not static).
7672 ("!prefix is non-static array (RM 4.9(8))", Prefix
(N
));
7677 -- Special case generic types, since again this is a common source
7680 elsif Is_Generic_Actual_Type
(E
) or else Is_Generic_Type
(E
) then
7682 ("!attribute of generic type is never static "
7683 & "(RM 4.9(7,8))", N
);
7685 elsif Is_OK_Static_Subtype
(E
) then
7688 elsif Is_Scalar_Type
(E
) then
7690 ("!prefix type for attribute is not static scalar subtype "
7691 & "(RM 4.9(7))", N
);
7695 ("!static attribute must apply to array/scalar type "
7696 & "(RM 4.9(7,8))", N
);
7701 when N_String_Literal
=>
7703 ("!subtype of string literal is non-static (RM 4.9(4))", N
);
7705 -- Explicit dereference
7707 when N_Explicit_Dereference
=>
7709 ("!explicit dereference is never static (RM 4.9)", N
);
7713 when N_Function_Call
=>
7714 Why_Not_Static_List
(Parameter_Associations
(N
));
7716 -- Complain about non-static function call unless we have Bignum
7717 -- which means that the underlying expression is really some
7718 -- scalar arithmetic operation.
7720 if not Is_RTE
(Typ
, RE_Bignum
) then
7721 Error_Msg_N
("!non-static function call (RM 4.9(6,18))", N
);
7724 -- Parameter assocation (test actual parameter)
7726 when N_Parameter_Association
=>
7727 Why_Not_Static
(Explicit_Actual_Parameter
(N
));
7729 -- Indexed component
7731 when N_Indexed_Component
=>
7732 Error_Msg_N
("!indexed component is never static (RM 4.9)", N
);
7736 when N_Procedure_Call_Statement
=>
7737 Error_Msg_N
("!procedure call is never static (RM 4.9)", N
);
7739 -- Qualified expression (test expression)
7741 when N_Qualified_Expression
=>
7742 Why_Not_Static
(Expression
(N
));
7747 | N_Extension_Aggregate
7749 Error_Msg_N
("!an aggregate is never static (RM 4.9)", N
);
7754 Why_Not_Static
(Low_Bound
(N
));
7755 Why_Not_Static
(High_Bound
(N
));
7757 -- Range constraint, test range expression
7759 when N_Range_Constraint
=>
7760 Why_Not_Static
(Range_Expression
(N
));
7762 -- Subtype indication, test constraint
7764 when N_Subtype_Indication
=>
7765 Why_Not_Static
(Constraint
(N
));
7767 -- Selected component
7769 when N_Selected_Component
=>
7770 Error_Msg_N
("!selected component is never static (RM 4.9)", N
);
7775 Error_Msg_N
("!slice is never static (RM 4.9)", N
);
7777 when N_Type_Conversion
=>
7778 Why_Not_Static
(Expression
(N
));
7780 if not Is_Scalar_Type
(Entity
(Subtype_Mark
(N
)))
7781 or else not Is_OK_Static_Subtype
(Entity
(Subtype_Mark
(N
)))
7784 ("!static conversion requires static scalar subtype result "
7785 & "(RM 4.9(9))", N
);
7788 -- Unchecked type conversion
7790 when N_Unchecked_Type_Conversion
=>
7792 ("!unchecked type conversion is never static (RM 4.9)", N
);
7794 -- All other cases, no reason to give