1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2018, 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 Elists
; use Elists
;
32 with Errout
; use Errout
;
33 with Eval_Fat
; use Eval_Fat
;
34 with Exp_Util
; use Exp_Util
;
35 with Freeze
; use Freeze
;
37 with Namet
; use Namet
;
38 with Nmake
; use Nmake
;
39 with Nlists
; use Nlists
;
41 with Par_SCO
; use Par_SCO
;
42 with Rtsfind
; use Rtsfind
;
44 with Sem_Aux
; use Sem_Aux
;
45 with Sem_Cat
; use Sem_Cat
;
46 with Sem_Ch6
; use Sem_Ch6
;
47 with Sem_Ch8
; use Sem_Ch8
;
48 with Sem_Res
; use Sem_Res
;
49 with Sem_Util
; use Sem_Util
;
50 with Sem_Type
; use Sem_Type
;
51 with Sem_Warn
; use Sem_Warn
;
52 with Sinfo
; use Sinfo
;
53 with Snames
; use Snames
;
54 with Stand
; use Stand
;
55 with Stringt
; use Stringt
;
56 with Tbuild
; use Tbuild
;
58 package body Sem_Eval
is
60 -----------------------------------------
61 -- Handling of Compile Time Evaluation --
62 -----------------------------------------
64 -- The compile time evaluation of expressions is distributed over several
65 -- Eval_xxx procedures. These procedures are called immediately after
66 -- a subexpression is resolved and is therefore accomplished in a bottom
67 -- up fashion. The flags are synthesized using the following approach.
69 -- Is_Static_Expression is determined by following the rules in
70 -- RM-4.9. This involves testing the Is_Static_Expression flag of
71 -- the operands in many cases.
73 -- Raises_Constraint_Error is usually set if any of the operands have
74 -- the flag set or if an attempt to compute the value of the current
75 -- expression results in Constraint_Error.
77 -- The general approach is as follows. First compute Is_Static_Expression.
78 -- If the node is not static, then the flag is left off in the node and
79 -- we are all done. Otherwise for a static node, we test if any of the
80 -- operands will raise Constraint_Error, and if so, propagate the flag
81 -- Raises_Constraint_Error to the result node and we are done (since the
82 -- error was already posted at a lower level).
84 -- For the case of a static node whose operands do not raise constraint
85 -- error, we attempt to evaluate the node. If this evaluation succeeds,
86 -- then the node is replaced by the result of this computation. If the
87 -- evaluation raises Constraint_Error, then we rewrite the node with
88 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
89 -- to post appropriate error messages.
95 type Bits
is array (Nat
range <>) of Boolean;
96 -- Used to convert unsigned (modular) values for folding logical ops
98 -- The following declarations are used to maintain a cache of nodes that
99 -- have compile-time-known values. The cache is maintained only for
100 -- discrete types (the most common case), and is populated by calls to
101 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
102 -- since it is possible for the status to change (in particular it is
103 -- possible for a node to get replaced by a Constraint_Error node).
105 CV_Bits
: constant := 5;
106 -- Number of low order bits of Node_Id value used to reference entries
107 -- in the cache table.
109 CV_Cache_Size
: constant Nat
:= 2 ** CV_Bits
;
110 -- Size of cache for compile time values
112 subtype CV_Range
is Nat
range 0 .. CV_Cache_Size
;
114 type CV_Entry
is record
119 type Match_Result
is (Match
, No_Match
, Non_Static
);
120 -- Result returned from functions that test for a matching result. If the
121 -- operands are not OK_Static then Non_Static will be returned. Otherwise
122 -- Match/No_Match is returned depending on whether the match succeeds.
124 type CV_Cache_Array
is array (CV_Range
) of CV_Entry
;
126 CV_Cache
: CV_Cache_Array
:= (others => (Node_High_Bound
, Uint_0
));
127 -- This is the actual cache, with entries consisting of node/value pairs,
128 -- and the impossible value Node_High_Bound used for unset entries.
130 type Range_Membership
is (In_Range
, Out_Of_Range
, Unknown
);
131 -- Range membership may either be statically known to be in range or out
132 -- of range, or not statically known. Used for Test_In_Range below.
134 -----------------------
135 -- Local Subprograms --
136 -----------------------
138 function Choice_Matches
140 Choice
: Node_Id
) return Match_Result
;
141 -- Determines whether given value Expr matches the given Choice. The Expr
142 -- can be of discrete, real, or string type and must be a compile time
143 -- known value (it is an error to make the call if these conditions are
144 -- not met). The choice can be a range, subtype name, subtype indication,
145 -- or expression. The returned result is Non_Static if Choice is not
146 -- OK_Static, otherwise either Match or No_Match is returned depending
147 -- on whether Choice matches Expr. This is used for case expression
148 -- alternatives, and also for membership tests. In each case, more
149 -- possibilities are tested than the syntax allows (e.g. membership allows
150 -- subtype indications and non-discrete types, and case allows an OTHERS
151 -- choice), but it does not matter, since we have already done a full
152 -- semantic and syntax check of the construct, so the extra possibilities
153 -- just will not arise for correct expressions.
155 -- Note: if Choice_Matches finds that a choice raises Constraint_Error, e.g
156 -- a reference to a type, one of whose bounds raises Constraint_Error, then
157 -- it also sets the Raises_Constraint_Error flag on the Choice itself.
159 function Choices_Match
161 Choices
: List_Id
) return Match_Result
;
162 -- This function applies Choice_Matches to each element of Choices. If the
163 -- result is No_Match, then it continues and checks the next element. If
164 -- the result is Match or Non_Static, this result is immediately given
165 -- as the result without checking the rest of the list. Expr can be of
166 -- discrete, real, or string type and must be a compile-time-known value
167 -- (it is an error to make the call if these conditions are not met).
169 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
;
170 -- Check whether an arithmetic operation with universal operands which is a
171 -- rewritten function call with an explicit scope indication is ambiguous:
172 -- P."+" (1, 2) will be ambiguous if there is more than one visible numeric
173 -- type declared in P and the context does not impose a type on the result
174 -- (e.g. in the expression of a type conversion). If ambiguous, emit an
175 -- error and return Empty, else return the result type of the operator.
177 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
;
178 -- Converts a bit string of length B'Length to a Uint value to be used for
179 -- a target of type T, which is a modular type. This procedure includes the
180 -- necessary reduction by the modulus in the case of a nonbinary modulus
181 -- (for a binary modulus, the bit string is the right length any way so all
184 function Get_String_Val
(N
: Node_Id
) return Node_Id
;
185 -- Given a tree node for a folded string or character value, returns the
186 -- corresponding string literal or character literal (one of the two must
187 -- be available, or the operand would not have been marked as foldable in
188 -- the earlier analysis of the operation).
190 function Is_OK_Static_Choice
(Choice
: Node_Id
) return Boolean;
191 -- Given a choice (from a case expression or membership test), returns
192 -- True if the choice is static and does not raise a Constraint_Error.
194 function Is_OK_Static_Choice_List
(Choices
: List_Id
) return Boolean;
195 -- Given a choice list (from a case expression or membership test), return
196 -- True if all choices are static in the sense of Is_OK_Static_Choice.
198 function Is_Static_Choice
(Choice
: Node_Id
) return Boolean;
199 -- Given a choice (from a case expression or membership test), returns
200 -- True if the choice is static. No test is made for raising of constraint
201 -- error, so this function is used only for legality tests.
203 function Is_Static_Choice_List
(Choices
: List_Id
) return Boolean;
204 -- Given a choice list (from a case expression or membership test), return
205 -- True if all choices are static in the sense of Is_Static_Choice.
207 function Is_Static_Range
(N
: Node_Id
) return Boolean;
208 -- Determine if range is static, as defined in RM 4.9(26). The only allowed
209 -- argument is an N_Range node (but note that the semantic analysis of
210 -- equivalent range attribute references already turned them into the
211 -- equivalent range). This differs from Is_OK_Static_Range (which is what
212 -- must be used by clients) in that it does not care whether the bounds
213 -- raise Constraint_Error or not. Used for checking whether expressions are
214 -- static in the 4.9 sense (without worrying about exceptions).
216 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean;
217 -- Bits represents the number of bits in an integer value to be computed
218 -- (but the value has not been computed yet). If this value in Bits is
219 -- reasonable, a result of True is returned, with the implication that the
220 -- caller should go ahead and complete the calculation. If the value in
221 -- Bits is unreasonably large, then an error is posted on node N, and
222 -- False is returned (and the caller skips the proposed calculation).
224 procedure Out_Of_Range
(N
: Node_Id
);
225 -- This procedure is called if it is determined that node N, which appears
226 -- in a non-static context, is a compile-time-known value which is outside
227 -- its range, i.e. the range of Etype. This is used in contexts where
228 -- this is an illegality if N is static, and should generate a warning
231 function Real_Or_String_Static_Predicate_Matches
233 Typ
: Entity_Id
) return Boolean;
234 -- This is the function used to evaluate real or string static predicates.
235 -- Val is an unanalyzed N_Real_Literal or N_String_Literal node, which
236 -- represents the value to be tested against the predicate. Typ is the
237 -- type with the predicate, from which the predicate expression can be
238 -- extracted. The result returned is True if the given value satisfies
241 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
);
242 -- N and Exp are nodes representing an expression, Exp is known to raise
243 -- CE. N is rewritten in term of Exp in the optimal way.
245 function String_Type_Len
(Stype
: Entity_Id
) return Uint
;
246 -- Given a string type, determines the length of the index type, or, if
247 -- this index type is non-static, the length of the base type of this index
248 -- type. Note that if the string type is itself static, then the index type
249 -- is static, so the second case applies only if the string type passed is
252 function Test
(Cond
: Boolean) return Uint
;
253 pragma Inline
(Test
);
254 -- This function simply returns the appropriate Boolean'Pos value
255 -- corresponding to the value of Cond as a universal integer. It is
256 -- used for producing the result of the static evaluation of the
259 procedure Test_Expression_Is_Foldable
264 -- Tests to see if expression N whose single operand is Op1 is foldable,
265 -- i.e. the operand value is known at compile time. If the operation is
266 -- foldable, then Fold is True on return, and Stat indicates whether the
267 -- result is static (i.e. the operand was static). Note that it is quite
268 -- possible for Fold to be True, and Stat to be False, since there are
269 -- cases in which we know the value of an operand even though it is not
270 -- technically static (e.g. the static lower bound of a range whose upper
271 -- bound is non-static).
273 -- If Stat is set False on return, then Test_Expression_Is_Foldable makes
274 -- a call to Check_Non_Static_Context on the operand. If Fold is False on
275 -- return, then all processing is complete, and the caller should return,
276 -- since there is nothing else to do.
278 -- If Stat is set True on return, then Is_Static_Expression is also set
279 -- true in node N. There are some cases where this is over-enthusiastic,
280 -- e.g. in the two operand case below, for string comparison, the result is
281 -- not static even though the two operands are static. In such cases, the
282 -- caller must reset the Is_Static_Expression flag in N.
284 -- If Fold and Stat are both set to False then this routine performs also
285 -- the following extra actions:
287 -- If either operand is Any_Type then propagate it to result to prevent
290 -- If some operand raises Constraint_Error, then replace the node N
291 -- with the raise Constraint_Error node. This replacement inherits the
292 -- Is_Static_Expression flag from the operands.
294 procedure Test_Expression_Is_Foldable
300 CRT_Safe
: Boolean := False);
301 -- Same processing, except applies to an expression N with two operands
302 -- Op1 and Op2. The result is static only if both operands are static. If
303 -- CRT_Safe is set True, then CRT_Safe_Compile_Time_Known_Value is used
304 -- for the tests that the two operands are known at compile time. See
305 -- spec of this routine for further details.
307 function Test_In_Range
310 Assume_Valid
: Boolean;
312 Int_Real
: Boolean) return Range_Membership
;
313 -- Common processing for Is_In_Range and Is_Out_Of_Range: Returns In_Range
314 -- or Out_Of_Range if it can be guaranteed at compile time that expression
315 -- N is known to be in or out of range of the subtype Typ. If not compile
316 -- time known, Unknown is returned. See documentation of Is_In_Range for
317 -- complete description of parameters.
319 procedure To_Bits
(U
: Uint
; B
: out Bits
);
320 -- Converts a Uint value to a bit string of length B'Length
322 -----------------------------------------------
323 -- Check_Expression_Against_Static_Predicate --
324 -----------------------------------------------
326 procedure Check_Expression_Against_Static_Predicate
331 -- Nothing to do if expression is not known at compile time, or the
332 -- type has no static predicate set (will be the case for all non-scalar
333 -- types, so no need to make a special test for that).
335 if not (Has_Static_Predicate
(Typ
)
336 and then Compile_Time_Known_Value
(Expr
))
341 -- Here we have a static predicate (note that it could have arisen from
342 -- an explicitly specified Dynamic_Predicate whose expression met the
343 -- rules for being predicate-static). If the expression is known at
344 -- compile time and obeys the predicate, then it is static and must be
345 -- labeled as such, which matters e.g. for case statements. The original
346 -- expression may be a type conversion of a variable with a known value,
347 -- which might otherwise not be marked static.
349 -- Case of real static predicate
351 if Is_Real_Type
(Typ
) then
352 if Real_Or_String_Static_Predicate_Matches
353 (Val
=> Make_Real_Literal
(Sloc
(Expr
), Expr_Value_R
(Expr
)),
356 Set_Is_Static_Expression
(Expr
);
360 -- Case of string static predicate
362 elsif Is_String_Type
(Typ
) then
363 if Real_Or_String_Static_Predicate_Matches
364 (Val
=> Expr_Value_S
(Expr
), Typ
=> Typ
)
366 Set_Is_Static_Expression
(Expr
);
370 -- Case of discrete static predicate
373 pragma Assert
(Is_Discrete_Type
(Typ
));
375 -- If static predicate matches, nothing to do
377 if Choices_Match
(Expr
, Static_Discrete_Predicate
(Typ
)) = Match
then
378 Set_Is_Static_Expression
(Expr
);
383 -- Here we know that the predicate will fail
385 -- Special case of static expression failing a predicate (other than one
386 -- that was explicitly specified with a Dynamic_Predicate aspect). This
387 -- is the case where the expression is no longer considered static.
389 if Is_Static_Expression
(Expr
)
390 and then not Has_Dynamic_Predicate_Aspect
(Typ
)
393 ("??static expression fails static predicate check on &",
396 ("\??expression is no longer considered static", Expr
);
397 Set_Is_Static_Expression
(Expr
, False);
399 -- In all other cases, this is just a warning that a test will fail.
400 -- It does not matter if the expression is static or not, or if the
401 -- predicate comes from a dynamic predicate aspect or not.
405 ("??expression fails predicate check on &", Expr
, Typ
);
407 end Check_Expression_Against_Static_Predicate
;
409 ------------------------------
410 -- Check_Non_Static_Context --
411 ------------------------------
413 procedure Check_Non_Static_Context
(N
: Node_Id
) is
414 T
: constant Entity_Id
:= Etype
(N
);
415 Checks_On
: constant Boolean :=
416 not Index_Checks_Suppressed
(T
)
417 and not Range_Checks_Suppressed
(T
);
420 -- Ignore cases of non-scalar types, error types, or universal real
421 -- types that have no usable bounds.
424 or else not Is_Scalar_Type
(T
)
425 or else T
= Universal_Fixed
426 or else T
= Universal_Real
431 -- At this stage we have a scalar type. If we have an expression that
432 -- raises CE, then we already issued a warning or error msg so there is
433 -- nothing more to be done in this routine.
435 if Raises_Constraint_Error
(N
) then
439 -- Now we have a scalar type which is not marked as raising a constraint
440 -- error exception. The main purpose of this routine is to deal with
441 -- static expressions appearing in a non-static context. That means
442 -- that if we do not have a static expression then there is not much
443 -- to do. The one case that we deal with here is that if we have a
444 -- floating-point value that is out of range, then we post a warning
445 -- that an infinity will result.
447 if not Is_Static_Expression
(N
) then
448 if Is_Floating_Point_Type
(T
) then
449 if Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
451 ("??float value out of range, infinity will be generated", N
);
453 -- The literal may be the result of constant-folding of a non-
454 -- static subexpression of a larger expression (e.g. a conversion
455 -- of a non-static variable whose value happens to be known). At
456 -- this point we must reduce the value of the subexpression to a
457 -- machine number (RM 4.9 (38/2)).
459 elsif Nkind
(N
) = N_Real_Literal
460 and then Nkind
(Parent
(N
)) in N_Subexpr
462 Rewrite
(N
, New_Copy
(N
));
464 (N
, Machine
(Base_Type
(T
), Realval
(N
), Round_Even
, N
));
471 -- Here we have the case of outer level static expression of scalar
472 -- type, where the processing of this procedure is needed.
474 -- For real types, this is where we convert the value to a machine
475 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should only
476 -- need to do this if the parent is a constant declaration, since in
477 -- other cases, gigi should do the necessary conversion correctly, but
478 -- experimentation shows that this is not the case on all machines, in
479 -- particular if we do not convert all literals to machine values in
480 -- non-static contexts, then ACVC test C490001 fails on Sparc/Solaris
483 -- This conversion is always done by GNATprove on real literals in
484 -- non-static expressions, by calling Check_Non_Static_Context from
485 -- gnat2why, as GNATprove cannot do the conversion later contrary
486 -- to gigi. The frontend computes the information about which
487 -- expressions are static, which is used by gnat2why to call
488 -- Check_Non_Static_Context on exactly those real literals that are
489 -- not subexpressions of static expressions.
491 if Nkind
(N
) = N_Real_Literal
492 and then not Is_Machine_Number
(N
)
493 and then not Is_Generic_Type
(Etype
(N
))
494 and then Etype
(N
) /= Universal_Real
496 -- Check that value is in bounds before converting to machine
497 -- number, so as not to lose case where value overflows in the
498 -- least significant bit or less. See B490001.
500 if Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
505 -- Note: we have to copy the node, to avoid problems with conformance
506 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
508 Rewrite
(N
, New_Copy
(N
));
510 if not Is_Floating_Point_Type
(T
) then
512 (N
, Corresponding_Integer_Value
(N
) * Small_Value
(T
));
514 elsif not UR_Is_Zero
(Realval
(N
)) then
516 -- Note: even though RM 4.9(38) specifies biased rounding, this
517 -- has been modified by AI-100 in order to prevent confusing
518 -- differences in rounding between static and non-static
519 -- expressions. AI-100 specifies that the effect of such rounding
520 -- is implementation dependent, and in GNAT we round to nearest
521 -- even to match the run-time behavior. Note that this applies
522 -- to floating point literals, not fixed points ones, even though
523 -- their compiler representation is also as a universal real.
526 (N
, Machine
(Base_Type
(T
), Realval
(N
), Round_Even
, N
));
527 Set_Is_Machine_Number
(N
);
532 -- Check for out of range universal integer. This is a non-static
533 -- context, so the integer value must be in range of the runtime
534 -- representation of universal integers.
536 -- We do this only within an expression, because that is the only
537 -- case in which non-static universal integer values can occur, and
538 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
539 -- called in contexts like the expression of a number declaration where
540 -- we certainly want to allow out of range values.
542 -- We inhibit the warning when expansion is disabled, because the
543 -- preanalysis of a range of a 64-bit modular type may appear to
544 -- violate the constraint on non-static Universal_Integer. If there
545 -- is a true overflow it will be diagnosed during full analysis.
547 if Etype
(N
) = Universal_Integer
548 and then Nkind
(N
) = N_Integer_Literal
549 and then Nkind
(Parent
(N
)) in N_Subexpr
550 and then Expander_Active
552 (Intval
(N
) < Expr_Value
(Type_Low_Bound
(Universal_Integer
))
554 Intval
(N
) > Expr_Value
(Type_High_Bound
(Universal_Integer
)))
556 Apply_Compile_Time_Constraint_Error
557 (N
, "non-static universal integer value out of range<<",
558 CE_Range_Check_Failed
);
560 -- Check out of range of base type
562 elsif Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
565 -- Give warning if outside subtype (where one or both of the bounds of
566 -- the subtype is static). This warning is omitted if the expression
567 -- appears in a range that could be null (warnings are handled elsewhere
570 elsif T
/= Base_Type
(T
) and then Nkind
(Parent
(N
)) /= N_Range
then
571 if Is_In_Range
(N
, T
, Assume_Valid
=> True) then
574 elsif Is_Out_Of_Range
(N
, T
, Assume_Valid
=> True) then
576 -- Ignore out of range values for System.Priority in CodePeer
577 -- mode since the actual target compiler may provide a wider
580 if CodePeer_Mode
and then T
= RTE
(RE_Priority
) then
581 Set_Do_Range_Check
(N
, False);
583 Apply_Compile_Time_Constraint_Error
584 (N
, "value not in range of}<<", CE_Range_Check_Failed
);
588 Enable_Range_Check
(N
);
591 Set_Do_Range_Check
(N
, False);
594 end Check_Non_Static_Context
;
596 ---------------------------------
597 -- Check_String_Literal_Length --
598 ---------------------------------
600 procedure Check_String_Literal_Length
(N
: Node_Id
; Ttype
: Entity_Id
) is
602 if not Raises_Constraint_Error
(N
) and then Is_Constrained
(Ttype
) then
603 if UI_From_Int
(String_Length
(Strval
(N
))) /= String_Type_Len
(Ttype
)
605 Apply_Compile_Time_Constraint_Error
606 (N
, "string length wrong for}??",
607 CE_Length_Check_Failed
,
612 end Check_String_Literal_Length
;
618 function Choice_Matches
620 Choice
: Node_Id
) return Match_Result
622 Etyp
: constant Entity_Id
:= Etype
(Expr
);
628 pragma Assert
(Compile_Time_Known_Value
(Expr
));
629 pragma Assert
(Is_Scalar_Type
(Etyp
) or else Is_String_Type
(Etyp
));
631 if not Is_OK_Static_Choice
(Choice
) then
632 Set_Raises_Constraint_Error
(Choice
);
635 -- When the choice denotes a subtype with a static predictate, check the
636 -- expression against the predicate values. Different procedures apply
637 -- to discrete and non-discrete types.
639 elsif (Nkind
(Choice
) = N_Subtype_Indication
640 or else (Is_Entity_Name
(Choice
)
641 and then Is_Type
(Entity
(Choice
))))
642 and then Has_Predicates
(Etype
(Choice
))
643 and then Has_Static_Predicate
(Etype
(Choice
))
645 if Is_Discrete_Type
(Etype
(Choice
)) then
648 (Expr
, Static_Discrete_Predicate
(Etype
(Choice
)));
650 elsif Real_Or_String_Static_Predicate_Matches
(Expr
, Etype
(Choice
))
658 -- Discrete type case only
660 elsif Is_Discrete_Type
(Etyp
) then
661 Val
:= Expr_Value
(Expr
);
663 if Nkind
(Choice
) = N_Range
then
664 if Val
>= Expr_Value
(Low_Bound
(Choice
))
666 Val
<= Expr_Value
(High_Bound
(Choice
))
673 elsif Nkind
(Choice
) = N_Subtype_Indication
674 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
676 if Val
>= Expr_Value
(Type_Low_Bound
(Etype
(Choice
)))
678 Val
<= Expr_Value
(Type_High_Bound
(Etype
(Choice
)))
685 elsif Nkind
(Choice
) = N_Others_Choice
then
689 if Val
= Expr_Value
(Choice
) then
698 elsif Is_Real_Type
(Etyp
) then
699 ValR
:= Expr_Value_R
(Expr
);
701 if Nkind
(Choice
) = N_Range
then
702 if ValR
>= Expr_Value_R
(Low_Bound
(Choice
))
704 ValR
<= Expr_Value_R
(High_Bound
(Choice
))
711 elsif Nkind
(Choice
) = N_Subtype_Indication
712 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
714 if ValR
>= Expr_Value_R
(Type_Low_Bound
(Etype
(Choice
)))
716 ValR
<= Expr_Value_R
(Type_High_Bound
(Etype
(Choice
)))
724 if ValR
= Expr_Value_R
(Choice
) then
734 pragma Assert
(Is_String_Type
(Etyp
));
735 ValS
:= Expr_Value_S
(Expr
);
737 if Nkind
(Choice
) = N_Subtype_Indication
738 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
740 if not Is_Constrained
(Etype
(Choice
)) then
745 Typlen
: constant Uint
:=
746 String_Type_Len
(Etype
(Choice
));
747 Strlen
: constant Uint
:=
748 UI_From_Int
(String_Length
(Strval
(ValS
)));
750 if Typlen
= Strlen
then
759 if String_Equal
(Strval
(ValS
), Strval
(Expr_Value_S
(Choice
)))
773 function Choices_Match
775 Choices
: List_Id
) return Match_Result
778 Result
: Match_Result
;
781 Choice
:= First
(Choices
);
782 while Present
(Choice
) loop
783 Result
:= Choice_Matches
(Expr
, Choice
);
785 if Result
/= No_Match
then
795 --------------------------
796 -- Compile_Time_Compare --
797 --------------------------
799 function Compile_Time_Compare
801 Assume_Valid
: Boolean) return Compare_Result
803 Discard
: aliased Uint
;
805 return Compile_Time_Compare
(L
, R
, Discard
'Access, Assume_Valid
);
806 end Compile_Time_Compare
;
808 function Compile_Time_Compare
811 Assume_Valid
: Boolean;
812 Rec
: Boolean := False) return Compare_Result
814 Ltyp
: Entity_Id
:= Etype
(L
);
815 Rtyp
: Entity_Id
:= Etype
(R
);
817 Discard
: aliased Uint
;
819 procedure Compare_Decompose
823 -- This procedure decomposes the node N into an expression node and a
824 -- signed offset, so that the value of N is equal to the value of R plus
825 -- the value V (which may be negative). If no such decomposition is
826 -- possible, then on return R is a copy of N, and V is set to zero.
828 function Compare_Fixup
(N
: Node_Id
) return Node_Id
;
829 -- This function deals with replacing 'Last and 'First references with
830 -- their corresponding type bounds, which we then can compare. The
831 -- argument is the original node, the result is the identity, unless we
832 -- have a 'Last/'First reference in which case the value returned is the
833 -- appropriate type bound.
835 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean;
836 -- Even if the context does not assume that values are valid, some
837 -- simple cases can be recognized.
839 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean;
840 -- Returns True iff L and R represent expressions that definitely have
841 -- identical (but not necessarily compile-time-known) values Indeed the
842 -- caller is expected to have already dealt with the cases of compile
843 -- time known values, so these are not tested here.
845 -----------------------
846 -- Compare_Decompose --
847 -----------------------
849 procedure Compare_Decompose
855 if Nkind
(N
) = N_Op_Add
856 and then Nkind
(Right_Opnd
(N
)) = N_Integer_Literal
859 V
:= Intval
(Right_Opnd
(N
));
862 elsif Nkind
(N
) = N_Op_Subtract
863 and then Nkind
(Right_Opnd
(N
)) = N_Integer_Literal
866 V
:= UI_Negate
(Intval
(Right_Opnd
(N
)));
869 elsif Nkind
(N
) = N_Attribute_Reference
then
870 if Attribute_Name
(N
) = Name_Succ
then
871 R
:= First
(Expressions
(N
));
875 elsif Attribute_Name
(N
) = Name_Pred
then
876 R
:= First
(Expressions
(N
));
884 end Compare_Decompose
;
890 function Compare_Fixup
(N
: Node_Id
) return Node_Id
is
896 -- Fixup only required for First/Last attribute reference
898 if Nkind
(N
) = N_Attribute_Reference
899 and then Nam_In
(Attribute_Name
(N
), Name_First
, Name_Last
)
901 Xtyp
:= Etype
(Prefix
(N
));
903 -- If we have no type, then just abandon the attempt to do
904 -- a fixup, this is probably the result of some other error.
910 -- Dereference an access type
912 if Is_Access_Type
(Xtyp
) then
913 Xtyp
:= Designated_Type
(Xtyp
);
916 -- If we don't have an array type at this stage, something is
917 -- peculiar, e.g. another error, and we abandon the attempt at
920 if not Is_Array_Type
(Xtyp
) then
924 -- Ignore unconstrained array, since bounds are not meaningful
926 if not Is_Constrained
(Xtyp
) then
930 if Ekind
(Xtyp
) = E_String_Literal_Subtype
then
931 if Attribute_Name
(N
) = Name_First
then
932 return String_Literal_Low_Bound
(Xtyp
);
935 Make_Integer_Literal
(Sloc
(N
),
936 Intval
=> Intval
(String_Literal_Low_Bound
(Xtyp
)) +
937 String_Literal_Length
(Xtyp
));
941 -- Find correct index type
943 Indx
:= First_Index
(Xtyp
);
945 if Present
(Expressions
(N
)) then
946 Subs
:= UI_To_Int
(Expr_Value
(First
(Expressions
(N
))));
948 for J
in 2 .. Subs
loop
949 Indx
:= Next_Index
(Indx
);
953 Xtyp
:= Etype
(Indx
);
955 if Attribute_Name
(N
) = Name_First
then
956 return Type_Low_Bound
(Xtyp
);
958 return Type_High_Bound
(Xtyp
);
965 ----------------------------
966 -- Is_Known_Valid_Operand --
967 ----------------------------
969 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean is
971 return (Is_Entity_Name
(Opnd
)
973 (Is_Known_Valid
(Entity
(Opnd
))
974 or else Ekind
(Entity
(Opnd
)) = E_In_Parameter
976 (Ekind
(Entity
(Opnd
)) in Object_Kind
977 and then Present
(Current_Value
(Entity
(Opnd
))))))
978 or else Is_OK_Static_Expression
(Opnd
);
979 end Is_Known_Valid_Operand
;
985 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean is
986 Lf
: constant Node_Id
:= Compare_Fixup
(L
);
987 Rf
: constant Node_Id
:= Compare_Fixup
(R
);
989 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean;
990 -- L, R are the Expressions values from two attribute nodes for First
991 -- or Last attributes. Either may be set to No_List if no expressions
992 -- are present (indicating subscript 1). The result is True if both
993 -- expressions represent the same subscript (note one case is where
994 -- one subscript is missing and the other is explicitly set to 1).
996 -----------------------
997 -- Is_Same_Subscript --
998 -----------------------
1000 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean is
1006 return Expr_Value
(First
(R
)) = Uint_1
;
1011 return Expr_Value
(First
(L
)) = Uint_1
;
1013 return Expr_Value
(First
(L
)) = Expr_Value
(First
(R
));
1016 end Is_Same_Subscript
;
1018 -- Start of processing for Is_Same_Value
1021 -- Values are the same if they refer to the same entity and the
1022 -- entity is non-volatile. This does not however apply to Float
1023 -- types, since we may have two NaN values and they should never
1026 -- If the entity is a discriminant, the two expressions may be bounds
1027 -- of components of objects of the same discriminated type. The
1028 -- values of the discriminants are not static, and therefore the
1029 -- result is unknown.
1031 -- It would be better to comment individual branches of this test ???
1033 if Nkind_In
(Lf
, N_Identifier
, N_Expanded_Name
)
1034 and then Nkind_In
(Rf
, N_Identifier
, N_Expanded_Name
)
1035 and then Entity
(Lf
) = Entity
(Rf
)
1036 and then Ekind
(Entity
(Lf
)) /= E_Discriminant
1037 and then Present
(Entity
(Lf
))
1038 and then not Is_Floating_Point_Type
(Etype
(L
))
1039 and then not Is_Volatile_Reference
(L
)
1040 and then not Is_Volatile_Reference
(R
)
1044 -- Or if they are compile-time-known and identical
1046 elsif Compile_Time_Known_Value
(Lf
)
1048 Compile_Time_Known_Value
(Rf
)
1049 and then Expr_Value
(Lf
) = Expr_Value
(Rf
)
1053 -- False if Nkind of the two nodes is different for remaining cases
1055 elsif Nkind
(Lf
) /= Nkind
(Rf
) then
1058 -- True if both 'First or 'Last values applying to the same entity
1059 -- (first and last don't change even if value does). Note that we
1060 -- need this even with the calls to Compare_Fixup, to handle the
1061 -- case of unconstrained array attributes where Compare_Fixup
1062 -- cannot find useful bounds.
1064 elsif Nkind
(Lf
) = N_Attribute_Reference
1065 and then Attribute_Name
(Lf
) = Attribute_Name
(Rf
)
1066 and then Nam_In
(Attribute_Name
(Lf
), Name_First
, Name_Last
)
1067 and then Nkind_In
(Prefix
(Lf
), N_Identifier
, N_Expanded_Name
)
1068 and then Nkind_In
(Prefix
(Rf
), N_Identifier
, N_Expanded_Name
)
1069 and then Entity
(Prefix
(Lf
)) = Entity
(Prefix
(Rf
))
1070 and then Is_Same_Subscript
(Expressions
(Lf
), Expressions
(Rf
))
1074 -- True if the same selected component from the same record
1076 elsif Nkind
(Lf
) = N_Selected_Component
1077 and then Selector_Name
(Lf
) = Selector_Name
(Rf
)
1078 and then Is_Same_Value
(Prefix
(Lf
), Prefix
(Rf
))
1082 -- True if the same unary operator applied to the same operand
1084 elsif Nkind
(Lf
) in N_Unary_Op
1085 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
1089 -- True if the same binary operator applied to the same operands
1091 elsif Nkind
(Lf
) in N_Binary_Op
1092 and then Is_Same_Value
(Left_Opnd
(Lf
), Left_Opnd
(Rf
))
1093 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
1097 -- All other cases, we can't tell, so return False
1104 -- Start of processing for Compile_Time_Compare
1107 Diff
.all := No_Uint
;
1109 -- In preanalysis mode, always return Unknown unless the expression
1110 -- is static. It is too early to be thinking we know the result of a
1111 -- comparison, save that judgment for the full analysis. This is
1112 -- particularly important in the case of pre and postconditions, which
1113 -- otherwise can be prematurely collapsed into having True or False
1114 -- conditions when this is inappropriate.
1116 if not (Full_Analysis
1117 or else (Is_OK_Static_Expression
(L
)
1119 Is_OK_Static_Expression
(R
)))
1124 -- If either operand could raise Constraint_Error, then we cannot
1125 -- know the result at compile time (since CE may be raised).
1127 if not (Cannot_Raise_Constraint_Error
(L
)
1129 Cannot_Raise_Constraint_Error
(R
))
1134 -- Identical operands are most certainly equal
1140 -- If expressions have no types, then do not attempt to determine if
1141 -- they are the same, since something funny is going on. One case in
1142 -- which this happens is during generic template analysis, when bounds
1143 -- are not fully analyzed.
1145 if No
(Ltyp
) or else No
(Rtyp
) then
1149 -- These get reset to the base type for the case of entities where
1150 -- Is_Known_Valid is not set. This takes care of handling possible
1151 -- invalid representations using the value of the base type, in
1152 -- accordance with RM 13.9.1(10).
1154 Ltyp
:= Underlying_Type
(Ltyp
);
1155 Rtyp
:= Underlying_Type
(Rtyp
);
1157 -- Same rationale as above, but for Underlying_Type instead of Etype
1159 if No
(Ltyp
) or else No
(Rtyp
) then
1163 -- We do not attempt comparisons for packed arrays represented as
1164 -- modular types, where the semantics of comparison is quite different.
1166 if Is_Packed_Array_Impl_Type
(Ltyp
)
1167 and then Is_Modular_Integer_Type
(Ltyp
)
1171 -- For access types, the only time we know the result at compile time
1172 -- (apart from identical operands, which we handled already) is if we
1173 -- know one operand is null and the other is not, or both operands are
1176 elsif Is_Access_Type
(Ltyp
) then
1177 if Known_Null
(L
) then
1178 if Known_Null
(R
) then
1180 elsif Known_Non_Null
(R
) then
1186 elsif Known_Non_Null
(L
) and then Known_Null
(R
) then
1193 -- Case where comparison involves two compile-time-known values
1195 elsif Compile_Time_Known_Value
(L
)
1197 Compile_Time_Known_Value
(R
)
1199 -- For the floating-point case, we have to be a little careful, since
1200 -- at compile time we are dealing with universal exact values, but at
1201 -- runtime, these will be in non-exact target form. That's why the
1202 -- returned results are LE and GE below instead of LT and GT.
1204 if Is_Floating_Point_Type
(Ltyp
)
1206 Is_Floating_Point_Type
(Rtyp
)
1209 Lo
: constant Ureal
:= Expr_Value_R
(L
);
1210 Hi
: constant Ureal
:= Expr_Value_R
(R
);
1221 -- For string types, we have two string literals and we proceed to
1222 -- compare them using the Ada style dictionary string comparison.
1224 elsif not Is_Scalar_Type
(Ltyp
) then
1226 Lstring
: constant String_Id
:= Strval
(Expr_Value_S
(L
));
1227 Rstring
: constant String_Id
:= Strval
(Expr_Value_S
(R
));
1228 Llen
: constant Nat
:= String_Length
(Lstring
);
1229 Rlen
: constant Nat
:= String_Length
(Rstring
);
1232 for J
in 1 .. Nat
'Min (Llen
, Rlen
) loop
1234 LC
: constant Char_Code
:= Get_String_Char
(Lstring
, J
);
1235 RC
: constant Char_Code
:= Get_String_Char
(Rstring
, J
);
1247 elsif Llen
> Rlen
then
1254 -- For remaining scalar cases we know exactly (note that this does
1255 -- include the fixed-point case, where we know the run time integer
1260 Lo
: constant Uint
:= Expr_Value
(L
);
1261 Hi
: constant Uint
:= Expr_Value
(R
);
1264 Diff
.all := Hi
- Lo
;
1269 Diff
.all := Lo
- Hi
;
1275 -- Cases where at least one operand is not known at compile time
1278 -- Remaining checks apply only for discrete types
1280 if not Is_Discrete_Type
(Ltyp
)
1282 not Is_Discrete_Type
(Rtyp
)
1287 -- Defend against generic types, or actually any expressions that
1288 -- contain a reference to a generic type from within a generic
1289 -- template. We don't want to do any range analysis of such
1290 -- expressions for two reasons. First, the bounds of a generic type
1291 -- itself are junk and cannot be used for any kind of analysis.
1292 -- Second, we may have a case where the range at run time is indeed
1293 -- known, but we don't want to do compile time analysis in the
1294 -- template based on that range since in an instance the value may be
1295 -- static, and able to be elaborated without reference to the bounds
1296 -- of types involved. As an example, consider:
1298 -- (F'Pos (F'Last) + 1) > Integer'Last
1300 -- The expression on the left side of > is Universal_Integer and thus
1301 -- acquires the type Integer for evaluation at run time, and at run
1302 -- time it is true that this condition is always False, but within
1303 -- an instance F may be a type with a static range greater than the
1304 -- range of Integer, and the expression statically evaluates to True.
1306 if References_Generic_Formal_Type
(L
)
1308 References_Generic_Formal_Type
(R
)
1313 -- Replace types by base types for the case of values which are not
1314 -- known to have valid representations. This takes care of properly
1315 -- dealing with invalid representations.
1317 if not Assume_Valid
then
1318 if not (Is_Entity_Name
(L
)
1319 and then (Is_Known_Valid
(Entity
(L
))
1320 or else Assume_No_Invalid_Values
))
1322 Ltyp
:= Underlying_Type
(Base_Type
(Ltyp
));
1325 if not (Is_Entity_Name
(R
)
1326 and then (Is_Known_Valid
(Entity
(R
))
1327 or else Assume_No_Invalid_Values
))
1329 Rtyp
:= Underlying_Type
(Base_Type
(Rtyp
));
1333 -- First attempt is to decompose the expressions to extract a
1334 -- constant offset resulting from the use of any of the forms:
1341 -- Then we see if the two expressions are the same value, and if so
1342 -- the result is obtained by comparing the offsets.
1344 -- Note: the reason we do this test first is that it returns only
1345 -- decisive results (with diff set), where other tests, like the
1346 -- range test, may not be as so decisive. Consider for example
1347 -- J .. J + 1. This code can conclude LT with a difference of 1,
1348 -- even if the range of J is not known.
1357 Compare_Decompose
(L
, Lnode
, Loffs
);
1358 Compare_Decompose
(R
, Rnode
, Roffs
);
1360 if Is_Same_Value
(Lnode
, Rnode
) then
1361 if Loffs
= Roffs
then
1365 -- When the offsets are not equal, we can go farther only if
1366 -- the types are not modular (e.g. X < X + 1 is False if X is
1367 -- the largest number).
1369 if not Is_Modular_Integer_Type
(Ltyp
)
1370 and then not Is_Modular_Integer_Type
(Rtyp
)
1372 if Loffs
< Roffs
then
1373 Diff
.all := Roffs
- Loffs
;
1376 Diff
.all := Loffs
- Roffs
;
1383 -- Next, try range analysis and see if operand ranges are disjoint
1391 -- True if each range is a single point
1394 Determine_Range
(L
, LOK
, LLo
, LHi
, Assume_Valid
);
1395 Determine_Range
(R
, ROK
, RLo
, RHi
, Assume_Valid
);
1398 Single
:= (LLo
= LHi
) and then (RLo
= RHi
);
1401 if Single
and Assume_Valid
then
1402 Diff
.all := RLo
- LLo
;
1407 elsif RHi
< LLo
then
1408 if Single
and Assume_Valid
then
1409 Diff
.all := LLo
- RLo
;
1414 elsif Single
and then LLo
= RLo
then
1416 -- If the range includes a single literal and we can assume
1417 -- validity then the result is known even if an operand is
1420 if Assume_Valid
then
1426 elsif LHi
= RLo
then
1429 elsif RHi
= LLo
then
1432 elsif not Is_Known_Valid_Operand
(L
)
1433 and then not Assume_Valid
1435 if Is_Same_Value
(L
, R
) then
1442 -- If the range of either operand cannot be determined, nothing
1443 -- further can be inferred.
1450 -- Here is where we check for comparisons against maximum bounds of
1451 -- types, where we know that no value can be outside the bounds of
1452 -- the subtype. Note that this routine is allowed to assume that all
1453 -- expressions are within their subtype bounds. Callers wishing to
1454 -- deal with possibly invalid values must in any case take special
1455 -- steps (e.g. conversions to larger types) to avoid this kind of
1456 -- optimization, which is always considered to be valid. We do not
1457 -- attempt this optimization with generic types, since the type
1458 -- bounds may not be meaningful in this case.
1460 -- We are in danger of an infinite recursion here. It does not seem
1461 -- useful to go more than one level deep, so the parameter Rec is
1462 -- used to protect ourselves against this infinite recursion.
1466 -- See if we can get a decisive check against one operand and a
1467 -- bound of the other operand (four possible tests here). Note
1468 -- that we avoid testing junk bounds of a generic type.
1470 if not Is_Generic_Type
(Rtyp
) then
1471 case Compile_Time_Compare
(L
, Type_Low_Bound
(Rtyp
),
1473 Assume_Valid
, Rec
=> True)
1475 when LT
=> return LT
;
1476 when LE
=> return LE
;
1477 when EQ
=> return LE
;
1478 when others => null;
1481 case Compile_Time_Compare
(L
, Type_High_Bound
(Rtyp
),
1483 Assume_Valid
, Rec
=> True)
1485 when GT
=> return GT
;
1486 when GE
=> return GE
;
1487 when EQ
=> return GE
;
1488 when others => null;
1492 if not Is_Generic_Type
(Ltyp
) then
1493 case Compile_Time_Compare
(Type_Low_Bound
(Ltyp
), R
,
1495 Assume_Valid
, Rec
=> True)
1497 when GT
=> return GT
;
1498 when GE
=> return GE
;
1499 when EQ
=> return GE
;
1500 when others => null;
1503 case Compile_Time_Compare
(Type_High_Bound
(Ltyp
), R
,
1505 Assume_Valid
, Rec
=> True)
1507 when LT
=> return LT
;
1508 when LE
=> return LE
;
1509 when EQ
=> return LE
;
1510 when others => null;
1515 -- Next attempt is to see if we have an entity compared with a
1516 -- compile-time-known value, where there is a current value
1517 -- conditional for the entity which can tell us the result.
1521 -- Entity variable (left operand)
1524 -- Value (right operand)
1527 -- If False, we have reversed the operands
1530 -- Comparison operator kind from Get_Current_Value_Condition call
1533 -- Value from Get_Current_Value_Condition call
1538 Result
: Compare_Result
;
1539 -- Known result before inversion
1542 if Is_Entity_Name
(L
)
1543 and then Compile_Time_Known_Value
(R
)
1546 Val
:= Expr_Value
(R
);
1549 elsif Is_Entity_Name
(R
)
1550 and then Compile_Time_Known_Value
(L
)
1553 Val
:= Expr_Value
(L
);
1556 -- That was the last chance at finding a compile time result
1562 Get_Current_Value_Condition
(Var
, Op
, Opn
);
1564 -- That was the last chance, so if we got nothing return
1570 Opv
:= Expr_Value
(Opn
);
1572 -- We got a comparison, so we might have something interesting
1574 -- Convert LE to LT and GE to GT, just so we have fewer cases
1576 if Op
= N_Op_Le
then
1580 elsif Op
= N_Op_Ge
then
1585 -- Deal with equality case
1587 if Op
= N_Op_Eq
then
1590 elsif Opv
< Val
then
1596 -- Deal with inequality case
1598 elsif Op
= N_Op_Ne
then
1605 -- Deal with greater than case
1607 elsif Op
= N_Op_Gt
then
1610 elsif Opv
= Val
- 1 then
1616 -- Deal with less than case
1618 else pragma Assert
(Op
= N_Op_Lt
);
1621 elsif Opv
= Val
+ 1 then
1628 -- Deal with inverting result
1632 when GT
=> return LT
;
1633 when GE
=> return LE
;
1634 when LT
=> return GT
;
1635 when LE
=> return GE
;
1636 when others => return Result
;
1643 end Compile_Time_Compare
;
1645 -------------------------------
1646 -- Compile_Time_Known_Bounds --
1647 -------------------------------
1649 function Compile_Time_Known_Bounds
(T
: Entity_Id
) return Boolean is
1654 if T
= Any_Composite
or else not Is_Array_Type
(T
) then
1658 Indx
:= First_Index
(T
);
1659 while Present
(Indx
) loop
1660 Typ
:= Underlying_Type
(Etype
(Indx
));
1662 -- Never look at junk bounds of a generic type
1664 if Is_Generic_Type
(Typ
) then
1668 -- Otherwise check bounds for compile-time-known
1670 if not Compile_Time_Known_Value
(Type_Low_Bound
(Typ
)) then
1672 elsif not Compile_Time_Known_Value
(Type_High_Bound
(Typ
)) then
1680 end Compile_Time_Known_Bounds
;
1682 ------------------------------
1683 -- Compile_Time_Known_Value --
1684 ------------------------------
1686 function Compile_Time_Known_Value
(Op
: Node_Id
) return Boolean is
1687 K
: constant Node_Kind
:= Nkind
(Op
);
1688 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(Op
) mod CV_Cache_Size
);
1691 -- Never known at compile time if bad type or raises Constraint_Error
1692 -- or empty (latter case occurs only as a result of a previous error).
1695 Check_Error_Detected
;
1699 or else Etype
(Op
) = Any_Type
1700 or else Raises_Constraint_Error
(Op
)
1705 -- If we have an entity name, then see if it is the name of a constant
1706 -- and if so, test the corresponding constant value, or the name of an
1707 -- enumeration literal, which is always a constant.
1709 if Present
(Etype
(Op
)) and then Is_Entity_Name
(Op
) then
1711 Ent
: constant Entity_Id
:= Entity
(Op
);
1715 -- Never known at compile time if it is a packed array value. We
1716 -- might want to try to evaluate these at compile time one day,
1717 -- but we do not make that attempt now.
1719 if Is_Packed_Array_Impl_Type
(Etype
(Op
)) then
1722 elsif Ekind
(Ent
) = E_Enumeration_Literal
then
1725 elsif Ekind
(Ent
) = E_Constant
then
1726 Val
:= Constant_Value
(Ent
);
1728 if Present
(Val
) then
1730 -- Guard against an illegal deferred constant whose full
1731 -- view is initialized with a reference to itself. Treat
1732 -- this case as a value not known at compile time.
1734 if Is_Entity_Name
(Val
) and then Entity
(Val
) = Ent
then
1737 return Compile_Time_Known_Value
(Val
);
1740 -- Otherwise, the constant does not have a compile-time-known
1749 -- We have a value, see if it is compile-time-known
1752 -- Integer literals are worth storing in the cache
1754 if K
= N_Integer_Literal
then
1756 CV_Ent
.V
:= Intval
(Op
);
1759 -- Other literals and NULL are known at compile time
1762 Nkind_In
(K
, N_Character_Literal
,
1771 -- If we fall through, not known at compile time
1775 -- If we get an exception while trying to do this test, then some error
1776 -- has occurred, and we simply say that the value is not known after all
1781 end Compile_Time_Known_Value
;
1783 --------------------------------------
1784 -- Compile_Time_Known_Value_Or_Aggr --
1785 --------------------------------------
1787 function Compile_Time_Known_Value_Or_Aggr
(Op
: Node_Id
) return Boolean is
1789 -- If we have an entity name, then see if it is the name of a constant
1790 -- and if so, test the corresponding constant value, or the name of
1791 -- an enumeration literal, which is always a constant.
1793 if Is_Entity_Name
(Op
) then
1795 E
: constant Entity_Id
:= Entity
(Op
);
1799 if Ekind
(E
) = E_Enumeration_Literal
then
1802 elsif Ekind
(E
) /= E_Constant
then
1806 V
:= Constant_Value
(E
);
1808 and then Compile_Time_Known_Value_Or_Aggr
(V
);
1812 -- We have a value, see if it is compile-time-known
1815 if Compile_Time_Known_Value
(Op
) then
1818 elsif Nkind
(Op
) = N_Aggregate
then
1820 if Present
(Expressions
(Op
)) then
1824 Expr
:= First
(Expressions
(Op
));
1825 while Present
(Expr
) loop
1826 if not Compile_Time_Known_Value_Or_Aggr
(Expr
) then
1835 if Present
(Component_Associations
(Op
)) then
1840 Cass
:= First
(Component_Associations
(Op
));
1841 while Present
(Cass
) loop
1843 Compile_Time_Known_Value_Or_Aggr
(Expression
(Cass
))
1855 elsif Nkind
(Op
) = N_Qualified_Expression
then
1856 return Compile_Time_Known_Value_Or_Aggr
(Expression
(Op
));
1858 -- All other types of values are not known at compile time
1865 end Compile_Time_Known_Value_Or_Aggr
;
1867 ---------------------------------------
1868 -- CRT_Safe_Compile_Time_Known_Value --
1869 ---------------------------------------
1871 function CRT_Safe_Compile_Time_Known_Value
(Op
: Node_Id
) return Boolean is
1873 if (Configurable_Run_Time_Mode
or No_Run_Time_Mode
)
1874 and then not Is_OK_Static_Expression
(Op
)
1878 return Compile_Time_Known_Value
(Op
);
1880 end CRT_Safe_Compile_Time_Known_Value
;
1886 -- This is only called for actuals of functions that are not predefined
1887 -- operators (which have already been rewritten as operators at this
1888 -- stage), so the call can never be folded, and all that needs doing for
1889 -- the actual is to do the check for a non-static context.
1891 procedure Eval_Actual
(N
: Node_Id
) is
1893 Check_Non_Static_Context
(N
);
1896 --------------------
1897 -- Eval_Allocator --
1898 --------------------
1900 -- Allocators are never static, so all we have to do is to do the
1901 -- check for a non-static context if an expression is present.
1903 procedure Eval_Allocator
(N
: Node_Id
) is
1904 Expr
: constant Node_Id
:= Expression
(N
);
1906 if Nkind
(Expr
) = N_Qualified_Expression
then
1907 Check_Non_Static_Context
(Expression
(Expr
));
1911 ------------------------
1912 -- Eval_Arithmetic_Op --
1913 ------------------------
1915 -- Arithmetic operations are static functions, so the result is static
1916 -- if both operands are static (RM 4.9(7), 4.9(20)).
1918 procedure Eval_Arithmetic_Op
(N
: Node_Id
) is
1919 Left
: constant Node_Id
:= Left_Opnd
(N
);
1920 Right
: constant Node_Id
:= Right_Opnd
(N
);
1921 Ltype
: constant Entity_Id
:= Etype
(Left
);
1922 Rtype
: constant Entity_Id
:= Etype
(Right
);
1923 Otype
: Entity_Id
:= Empty
;
1928 -- If not foldable we are done
1930 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
1936 -- Otherwise attempt to fold
1938 if Is_Universal_Numeric_Type
(Etype
(Left
))
1940 Is_Universal_Numeric_Type
(Etype
(Right
))
1942 Otype
:= Find_Universal_Operator_Type
(N
);
1945 -- Fold for cases where both operands are of integer type
1947 if Is_Integer_Type
(Ltype
) and then Is_Integer_Type
(Rtype
) then
1949 Left_Int
: constant Uint
:= Expr_Value
(Left
);
1950 Right_Int
: constant Uint
:= Expr_Value
(Right
);
1956 Result
:= Left_Int
+ Right_Int
;
1958 when N_Op_Subtract
=>
1959 Result
:= Left_Int
- Right_Int
;
1961 when N_Op_Multiply
=>
1964 (Num_Bits
(Left_Int
) + Num_Bits
(Right_Int
)))
1966 Result
:= Left_Int
* Right_Int
;
1973 -- The exception Constraint_Error is raised by integer
1974 -- division, rem and mod if the right operand is zero.
1976 if Right_Int
= 0 then
1978 -- When SPARK_Mode is On, force a warning instead of
1979 -- an error in that case, as this likely corresponds
1980 -- to deactivated code.
1982 Apply_Compile_Time_Constraint_Error
1983 (N
, "division by zero", CE_Divide_By_Zero
,
1984 Warn
=> not Stat
or SPARK_Mode
= On
);
1985 Set_Raises_Constraint_Error
(N
);
1988 -- Otherwise we can do the division
1991 Result
:= Left_Int
/ Right_Int
;
1996 -- The exception Constraint_Error is raised by integer
1997 -- division, rem and mod if the right operand is zero.
1999 if Right_Int
= 0 then
2001 -- When SPARK_Mode is On, force a warning instead of
2002 -- an error in that case, as this likely corresponds
2003 -- to deactivated code.
2005 Apply_Compile_Time_Constraint_Error
2006 (N
, "mod with zero divisor", CE_Divide_By_Zero
,
2007 Warn
=> not Stat
or SPARK_Mode
= On
);
2011 Result
:= Left_Int
mod Right_Int
;
2016 -- The exception Constraint_Error is raised by integer
2017 -- division, rem and mod if the right operand is zero.
2019 if Right_Int
= 0 then
2021 -- When SPARK_Mode is On, force a warning instead of
2022 -- an error in that case, as this likely corresponds
2023 -- to deactivated code.
2025 Apply_Compile_Time_Constraint_Error
2026 (N
, "rem with zero divisor", CE_Divide_By_Zero
,
2027 Warn
=> not Stat
or SPARK_Mode
= On
);
2031 Result
:= Left_Int
rem Right_Int
;
2035 raise Program_Error
;
2038 -- Adjust the result by the modulus if the type is a modular type
2040 if Is_Modular_Integer_Type
(Ltype
) then
2041 Result
:= Result
mod Modulus
(Ltype
);
2043 -- For a signed integer type, check non-static overflow
2045 elsif (not Stat
) and then Is_Signed_Integer_Type
(Ltype
) then
2047 BT
: constant Entity_Id
:= Base_Type
(Ltype
);
2048 Lo
: constant Uint
:= Expr_Value
(Type_Low_Bound
(BT
));
2049 Hi
: constant Uint
:= Expr_Value
(Type_High_Bound
(BT
));
2051 if Result
< Lo
or else Result
> Hi
then
2052 Apply_Compile_Time_Constraint_Error
2053 (N
, "value not in range of }??",
2054 CE_Overflow_Check_Failed
,
2061 -- If we get here we can fold the result
2063 Fold_Uint
(N
, Result
, Stat
);
2066 -- Cases where at least one operand is a real. We handle the cases of
2067 -- both reals, or mixed/real integer cases (the latter happen only for
2068 -- divide and multiply, and the result is always real).
2070 elsif Is_Real_Type
(Ltype
) or else Is_Real_Type
(Rtype
) then
2077 if Is_Real_Type
(Ltype
) then
2078 Left_Real
:= Expr_Value_R
(Left
);
2080 Left_Real
:= UR_From_Uint
(Expr_Value
(Left
));
2083 if Is_Real_Type
(Rtype
) then
2084 Right_Real
:= Expr_Value_R
(Right
);
2086 Right_Real
:= UR_From_Uint
(Expr_Value
(Right
));
2089 if Nkind
(N
) = N_Op_Add
then
2090 Result
:= Left_Real
+ Right_Real
;
2092 elsif Nkind
(N
) = N_Op_Subtract
then
2093 Result
:= Left_Real
- Right_Real
;
2095 elsif Nkind
(N
) = N_Op_Multiply
then
2096 Result
:= Left_Real
* Right_Real
;
2098 else pragma Assert
(Nkind
(N
) = N_Op_Divide
);
2099 if UR_Is_Zero
(Right_Real
) then
2100 Apply_Compile_Time_Constraint_Error
2101 (N
, "division by zero", CE_Divide_By_Zero
);
2105 Result
:= Left_Real
/ Right_Real
;
2108 Fold_Ureal
(N
, Result
, Stat
);
2112 -- If the operator was resolved to a specific type, make sure that type
2113 -- is frozen even if the expression is folded into a literal (which has
2114 -- a universal type).
2116 if Present
(Otype
) then
2117 Freeze_Before
(N
, Otype
);
2119 end Eval_Arithmetic_Op
;
2121 ----------------------------
2122 -- Eval_Character_Literal --
2123 ----------------------------
2125 -- Nothing to be done
2127 procedure Eval_Character_Literal
(N
: Node_Id
) is
2128 pragma Warnings
(Off
, N
);
2131 end Eval_Character_Literal
;
2137 -- Static function calls are either calls to predefined operators
2138 -- with static arguments, or calls to functions that rename a literal.
2139 -- Only the latter case is handled here, predefined operators are
2140 -- constant-folded elsewhere.
2142 -- If the function is itself inherited (see 7423-001) the literal of
2143 -- the parent type must be explicitly converted to the return type
2146 procedure Eval_Call
(N
: Node_Id
) is
2147 Loc
: constant Source_Ptr
:= Sloc
(N
);
2148 Typ
: constant Entity_Id
:= Etype
(N
);
2152 if Nkind
(N
) = N_Function_Call
2153 and then No
(Parameter_Associations
(N
))
2154 and then Is_Entity_Name
(Name
(N
))
2155 and then Present
(Alias
(Entity
(Name
(N
))))
2156 and then Is_Enumeration_Type
(Base_Type
(Typ
))
2158 Lit
:= Ultimate_Alias
(Entity
(Name
(N
)));
2160 if Ekind
(Lit
) = E_Enumeration_Literal
then
2161 if Base_Type
(Etype
(Lit
)) /= Base_Type
(Typ
) then
2163 (N
, Convert_To
(Typ
, New_Occurrence_Of
(Lit
, Loc
)));
2165 Rewrite
(N
, New_Occurrence_Of
(Lit
, Loc
));
2173 --------------------------
2174 -- Eval_Case_Expression --
2175 --------------------------
2177 -- A conditional expression is static if all its conditions and dependent
2178 -- expressions are static. Note that we do not care if the dependent
2179 -- expressions raise CE, except for the one that will be selected.
2181 procedure Eval_Case_Expression
(N
: Node_Id
) is
2186 Set_Is_Static_Expression
(N
, False);
2188 if Error_Posted
(Expression
(N
))
2189 or else not Is_Static_Expression
(Expression
(N
))
2191 Check_Non_Static_Context
(Expression
(N
));
2195 -- First loop, make sure all the alternatives are static expressions
2196 -- none of which raise Constraint_Error. We make the Constraint_Error
2197 -- check because part of the legality condition for a correct static
2198 -- case expression is that the cases are covered, like any other case
2199 -- expression. And we can't do that if any of the conditions raise an
2200 -- exception, so we don't even try to evaluate if that is the case.
2202 Alt
:= First
(Alternatives
(N
));
2203 while Present
(Alt
) loop
2205 -- The expression must be static, but we don't care at this stage
2206 -- if it raises Constraint_Error (the alternative might not match,
2207 -- in which case the expression is statically unevaluated anyway).
2209 if not Is_Static_Expression
(Expression
(Alt
)) then
2210 Check_Non_Static_Context
(Expression
(Alt
));
2214 -- The choices of a case always have to be static, and cannot raise
2215 -- an exception. If this condition is not met, then the expression
2216 -- is plain illegal, so just abandon evaluation attempts. No need
2217 -- to check non-static context when we have something illegal anyway.
2219 if not Is_OK_Static_Choice_List
(Discrete_Choices
(Alt
)) then
2226 -- OK, if the above loop gets through it means that all choices are OK
2227 -- static (don't raise exceptions), so the whole case is static, and we
2228 -- can find the matching alternative.
2230 Set_Is_Static_Expression
(N
);
2232 -- Now to deal with propagating a possible Constraint_Error
2234 -- If the selecting expression raises CE, propagate and we are done
2236 if Raises_Constraint_Error
(Expression
(N
)) then
2237 Set_Raises_Constraint_Error
(N
);
2239 -- Otherwise we need to check the alternatives to find the matching
2240 -- one. CE's in other than the matching one are not relevant. But we
2241 -- do need to check the matching one. Unlike the first loop, we do not
2242 -- have to go all the way through, when we find the matching one, quit.
2245 Alt
:= First
(Alternatives
(N
));
2248 -- We must find a match among the alternatives. If not, this must
2249 -- be due to other errors, so just ignore, leaving as non-static.
2252 Set_Is_Static_Expression
(N
, False);
2256 -- Otherwise loop through choices of this alternative
2258 Choice
:= First
(Discrete_Choices
(Alt
));
2259 while Present
(Choice
) loop
2261 -- If we find a matching choice, then the Expression of this
2262 -- alternative replaces N (Raises_Constraint_Error flag is
2263 -- included, so we don't have to special case that).
2265 if Choice_Matches
(Expression
(N
), Choice
) = Match
then
2266 Rewrite
(N
, Relocate_Node
(Expression
(Alt
)));
2276 end Eval_Case_Expression
;
2278 ------------------------
2279 -- Eval_Concatenation --
2280 ------------------------
2282 -- Concatenation is a static function, so the result is static if both
2283 -- operands are static (RM 4.9(7), 4.9(21)).
2285 procedure Eval_Concatenation
(N
: Node_Id
) is
2286 Left
: constant Node_Id
:= Left_Opnd
(N
);
2287 Right
: constant Node_Id
:= Right_Opnd
(N
);
2288 C_Typ
: constant Entity_Id
:= Root_Type
(Component_Type
(Etype
(N
)));
2293 -- Concatenation is never static in Ada 83, so if Ada 83 check operand
2294 -- non-static context.
2296 if Ada_Version
= Ada_83
2297 and then Comes_From_Source
(N
)
2299 Check_Non_Static_Context
(Left
);
2300 Check_Non_Static_Context
(Right
);
2304 -- If not foldable we are done. In principle concatenation that yields
2305 -- any string type is static (i.e. an array type of character types).
2306 -- However, character types can include enumeration literals, and
2307 -- concatenation in that case cannot be described by a literal, so we
2308 -- only consider the operation static if the result is an array of
2309 -- (a descendant of) a predefined character type.
2311 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2313 if not (Is_Standard_Character_Type
(C_Typ
) and then Fold
) then
2314 Set_Is_Static_Expression
(N
, False);
2318 -- Compile time string concatenation
2320 -- ??? Note that operands that are aggregates can be marked as static,
2321 -- so we should attempt at a later stage to fold concatenations with
2325 Left_Str
: constant Node_Id
:= Get_String_Val
(Left
);
2327 Right_Str
: constant Node_Id
:= Get_String_Val
(Right
);
2328 Folded_Val
: String_Id
:= No_String
;
2331 -- Establish new string literal, and store left operand. We make
2332 -- sure to use the special Start_String that takes an operand if
2333 -- the left operand is a string literal. Since this is optimized
2334 -- in the case where that is the most recently created string
2335 -- literal, we ensure efficient time/space behavior for the
2336 -- case of a concatenation of a series of string literals.
2338 if Nkind
(Left_Str
) = N_String_Literal
then
2339 Left_Len
:= String_Length
(Strval
(Left_Str
));
2341 -- If the left operand is the empty string, and the right operand
2342 -- is a string literal (the case of "" & "..."), the result is the
2343 -- value of the right operand. This optimization is important when
2344 -- Is_Folded_In_Parser, to avoid copying an enormous right
2347 if Left_Len
= 0 and then Nkind
(Right_Str
) = N_String_Literal
then
2348 Folded_Val
:= Strval
(Right_Str
);
2350 Start_String
(Strval
(Left_Str
));
2355 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Left_Str
)));
2359 -- Now append the characters of the right operand, unless we
2360 -- optimized the "" & "..." case above.
2362 if Nkind
(Right_Str
) = N_String_Literal
then
2363 if Left_Len
/= 0 then
2364 Store_String_Chars
(Strval
(Right_Str
));
2365 Folded_Val
:= End_String
;
2368 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Right_Str
)));
2369 Folded_Val
:= End_String
;
2372 Set_Is_Static_Expression
(N
, Stat
);
2374 -- If left operand is the empty string, the result is the
2375 -- right operand, including its bounds if anomalous.
2378 and then Is_Array_Type
(Etype
(Right
))
2379 and then Etype
(Right
) /= Any_String
2381 Set_Etype
(N
, Etype
(Right
));
2384 Fold_Str
(N
, Folded_Val
, Static
=> Stat
);
2386 end Eval_Concatenation
;
2388 ----------------------
2389 -- Eval_Entity_Name --
2390 ----------------------
2392 -- This procedure is used for identifiers and expanded names other than
2393 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
2394 -- static if they denote a static constant (RM 4.9(6)) or if the name
2395 -- denotes an enumeration literal (RM 4.9(22)).
2397 procedure Eval_Entity_Name
(N
: Node_Id
) is
2398 Def_Id
: constant Entity_Id
:= Entity
(N
);
2402 -- Enumeration literals are always considered to be constants
2403 -- and cannot raise Constraint_Error (RM 4.9(22)).
2405 if Ekind
(Def_Id
) = E_Enumeration_Literal
then
2406 Set_Is_Static_Expression
(N
);
2409 -- A name is static if it denotes a static constant (RM 4.9(5)), and
2410 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
2411 -- it does not violate 10.2.1(8) here, since this is not a variable.
2413 elsif Ekind
(Def_Id
) = E_Constant
then
2415 -- Deferred constants must always be treated as nonstatic outside the
2416 -- scope of their full view.
2418 if Present
(Full_View
(Def_Id
))
2419 and then not In_Open_Scopes
(Scope
(Def_Id
))
2423 Val
:= Constant_Value
(Def_Id
);
2426 if Present
(Val
) then
2427 Set_Is_Static_Expression
2428 (N
, Is_Static_Expression
(Val
)
2429 and then Is_Static_Subtype
(Etype
(Def_Id
)));
2430 Set_Raises_Constraint_Error
(N
, Raises_Constraint_Error
(Val
));
2432 if not Is_Static_Expression
(N
)
2433 and then not Is_Generic_Type
(Etype
(N
))
2435 Validate_Static_Object_Name
(N
);
2438 -- Mark constant condition in SCOs
2441 and then Comes_From_Source
(N
)
2442 and then Is_Boolean_Type
(Etype
(Def_Id
))
2443 and then Compile_Time_Known_Value
(N
)
2445 Set_SCO_Condition
(N
, Expr_Value_E
(N
) = Standard_True
);
2452 -- Fall through if the name is not static
2454 Validate_Static_Object_Name
(N
);
2455 end Eval_Entity_Name
;
2457 ------------------------
2458 -- Eval_If_Expression --
2459 ------------------------
2461 -- We can fold to a static expression if the condition and both dependent
2462 -- expressions are static. Otherwise, the only required processing is to do
2463 -- the check for non-static context for the then and else expressions.
2465 procedure Eval_If_Expression
(N
: Node_Id
) is
2466 Condition
: constant Node_Id
:= First
(Expressions
(N
));
2467 Then_Expr
: constant Node_Id
:= Next
(Condition
);
2468 Else_Expr
: constant Node_Id
:= Next
(Then_Expr
);
2470 Non_Result
: Node_Id
;
2472 Rstat
: constant Boolean :=
2473 Is_Static_Expression
(Condition
)
2475 Is_Static_Expression
(Then_Expr
)
2477 Is_Static_Expression
(Else_Expr
);
2478 -- True if result is static
2481 -- If result not static, nothing to do, otherwise set static result
2486 Set_Is_Static_Expression
(N
);
2489 -- If any operand is Any_Type, just propagate to result and do not try
2490 -- to fold, this prevents cascaded errors.
2492 if Etype
(Condition
) = Any_Type
or else
2493 Etype
(Then_Expr
) = Any_Type
or else
2494 Etype
(Else_Expr
) = Any_Type
2496 Set_Etype
(N
, Any_Type
);
2497 Set_Is_Static_Expression
(N
, False);
2501 -- If condition raises Constraint_Error then we have already signaled
2502 -- an error, and we just propagate to the result and do not fold.
2504 if Raises_Constraint_Error
(Condition
) then
2505 Set_Raises_Constraint_Error
(N
);
2509 -- Static case where we can fold. Note that we don't try to fold cases
2510 -- where the condition is known at compile time, but the result is
2511 -- non-static. This avoids possible cases of infinite recursion where
2512 -- the expander puts in a redundant test and we remove it. Instead we
2513 -- deal with these cases in the expander.
2515 -- Select result operand
2517 if Is_True
(Expr_Value
(Condition
)) then
2518 Result
:= Then_Expr
;
2519 Non_Result
:= Else_Expr
;
2521 Result
:= Else_Expr
;
2522 Non_Result
:= Then_Expr
;
2525 -- Note that it does not matter if the non-result operand raises a
2526 -- Constraint_Error, but if the result raises Constraint_Error then we
2527 -- replace the node with a raise Constraint_Error. This will properly
2528 -- propagate Raises_Constraint_Error since this flag is set in Result.
2530 if Raises_Constraint_Error
(Result
) then
2531 Rewrite_In_Raise_CE
(N
, Result
);
2532 Check_Non_Static_Context
(Non_Result
);
2534 -- Otherwise the result operand replaces the original node
2537 Rewrite
(N
, Relocate_Node
(Result
));
2538 Set_Is_Static_Expression
(N
);
2540 end Eval_If_Expression
;
2542 ----------------------------
2543 -- Eval_Indexed_Component --
2544 ----------------------------
2546 -- Indexed components are never static, so we need to perform the check
2547 -- for non-static context on the index values. Then, we check if the
2548 -- value can be obtained at compile time, even though it is non-static.
2550 procedure Eval_Indexed_Component
(N
: Node_Id
) is
2554 -- Check for non-static context on index values
2556 Expr
:= First
(Expressions
(N
));
2557 while Present
(Expr
) loop
2558 Check_Non_Static_Context
(Expr
);
2562 -- If the indexed component appears in an object renaming declaration
2563 -- then we do not want to try to evaluate it, since in this case we
2564 -- need the identity of the array element.
2566 if Nkind
(Parent
(N
)) = N_Object_Renaming_Declaration
then
2569 -- Similarly if the indexed component appears as the prefix of an
2570 -- attribute we don't want to evaluate it, because at least for
2571 -- some cases of attributes we need the identify (e.g. Access, Size)
2573 elsif Nkind
(Parent
(N
)) = N_Attribute_Reference
then
2577 -- Note: there are other cases, such as the left side of an assignment,
2578 -- or an OUT parameter for a call, where the replacement results in the
2579 -- illegal use of a constant, But these cases are illegal in the first
2580 -- place, so the replacement, though silly, is harmless.
2582 -- Now see if this is a constant array reference
2584 if List_Length
(Expressions
(N
)) = 1
2585 and then Is_Entity_Name
(Prefix
(N
))
2586 and then Ekind
(Entity
(Prefix
(N
))) = E_Constant
2587 and then Present
(Constant_Value
(Entity
(Prefix
(N
))))
2590 Loc
: constant Source_Ptr
:= Sloc
(N
);
2591 Arr
: constant Node_Id
:= Constant_Value
(Entity
(Prefix
(N
)));
2592 Sub
: constant Node_Id
:= First
(Expressions
(N
));
2598 -- Linear one's origin subscript value for array reference
2601 -- Lower bound of the first array index
2604 -- Value from constant array
2607 Atyp
:= Etype
(Arr
);
2609 if Is_Access_Type
(Atyp
) then
2610 Atyp
:= Designated_Type
(Atyp
);
2613 -- If we have an array type (we should have but perhaps there are
2614 -- error cases where this is not the case), then see if we can do
2615 -- a constant evaluation of the array reference.
2617 if Is_Array_Type
(Atyp
) and then Atyp
/= Any_Composite
then
2618 if Ekind
(Atyp
) = E_String_Literal_Subtype
then
2619 Lbd
:= String_Literal_Low_Bound
(Atyp
);
2621 Lbd
:= Type_Low_Bound
(Etype
(First_Index
(Atyp
)));
2624 if Compile_Time_Known_Value
(Sub
)
2625 and then Nkind
(Arr
) = N_Aggregate
2626 and then Compile_Time_Known_Value
(Lbd
)
2627 and then Is_Discrete_Type
(Component_Type
(Atyp
))
2629 Lin
:= UI_To_Int
(Expr_Value
(Sub
) - Expr_Value
(Lbd
)) + 1;
2631 if List_Length
(Expressions
(Arr
)) >= Lin
then
2632 Elm
:= Pick
(Expressions
(Arr
), Lin
);
2634 -- If the resulting expression is compile-time-known,
2635 -- then we can rewrite the indexed component with this
2636 -- value, being sure to mark the result as non-static.
2637 -- We also reset the Sloc, in case this generates an
2638 -- error later on (e.g. 136'Access).
2640 if Compile_Time_Known_Value
(Elm
) then
2641 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2642 Set_Is_Static_Expression
(N
, False);
2647 -- We can also constant-fold if the prefix is a string literal.
2648 -- This will be useful in an instantiation or an inlining.
2650 elsif Compile_Time_Known_Value
(Sub
)
2651 and then Nkind
(Arr
) = N_String_Literal
2652 and then Compile_Time_Known_Value
(Lbd
)
2653 and then Expr_Value
(Lbd
) = 1
2654 and then Expr_Value
(Sub
) <=
2655 String_Literal_Length
(Etype
(Arr
))
2658 C
: constant Char_Code
:=
2659 Get_String_Char
(Strval
(Arr
),
2660 UI_To_Int
(Expr_Value
(Sub
)));
2662 Set_Character_Literal_Name
(C
);
2665 Make_Character_Literal
(Loc
,
2667 Char_Literal_Value
=> UI_From_CC
(C
));
2668 Set_Etype
(Elm
, Component_Type
(Atyp
));
2669 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2670 Set_Is_Static_Expression
(N
, False);
2676 end Eval_Indexed_Component
;
2678 --------------------------
2679 -- Eval_Integer_Literal --
2680 --------------------------
2682 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2683 -- as static by the analyzer. The reason we did it that early is to allow
2684 -- the possibility of turning off the Is_Static_Expression flag after
2685 -- analysis, but before resolution, when integer literals are generated in
2686 -- the expander that do not correspond to static expressions.
2688 procedure Eval_Integer_Literal
(N
: Node_Id
) is
2689 function In_Any_Integer_Context
(Context
: Node_Id
) return Boolean;
2690 -- If the literal is resolved with a specific type in a context where
2691 -- the expected type is Any_Integer, there are no range checks on the
2692 -- literal. By the time the literal is evaluated, it carries the type
2693 -- imposed by the enclosing expression, and we must recover the context
2694 -- to determine that Any_Integer is meant.
2696 ----------------------------
2697 -- In_Any_Integer_Context --
2698 ----------------------------
2700 function In_Any_Integer_Context
(Context
: Node_Id
) return Boolean is
2702 -- Any_Integer also appears in digits specifications for real types,
2703 -- but those have bounds smaller that those of any integer base type,
2704 -- so we can safely ignore these cases.
2707 Nkind_In
(Context
, N_Attribute_Definition_Clause
,
2708 N_Attribute_Reference
,
2709 N_Modular_Type_Definition
,
2710 N_Number_Declaration
,
2711 N_Signed_Integer_Type_Definition
);
2712 end In_Any_Integer_Context
;
2716 Par
: constant Node_Id
:= Parent
(N
);
2717 Typ
: constant Entity_Id
:= Etype
(N
);
2719 -- Start of processing for Eval_Integer_Literal
2722 -- If the literal appears in a non-expression context, then it is
2723 -- certainly appearing in a non-static context, so check it. This is
2724 -- actually a redundant check, since Check_Non_Static_Context would
2725 -- check it, but it seems worthwhile to optimize out the call.
2727 -- Additionally, when the literal appears within an if or case
2728 -- expression it must be checked as well. However, due to the literal
2729 -- appearing within a conditional statement, expansion greatly changes
2730 -- the nature of its context and performing some of the checks within
2731 -- Check_Non_Static_Context on an expanded literal may lead to spurious
2732 -- and misleading warnings.
2734 if (Nkind_In
(Par
, N_Case_Expression_Alternative
, N_If_Expression
)
2735 or else Nkind
(Parent
(N
)) not in N_Subexpr
)
2736 and then (not Nkind_In
(Par
, N_Case_Expression_Alternative
,
2738 or else Comes_From_Source
(N
))
2739 and then not In_Any_Integer_Context
(Par
)
2741 Check_Non_Static_Context
(N
);
2744 -- Modular integer literals must be in their base range
2746 if Is_Modular_Integer_Type
(Typ
)
2747 and then Is_Out_Of_Range
(N
, Base_Type
(Typ
), Assume_Valid
=> True)
2751 end Eval_Integer_Literal
;
2753 ---------------------
2754 -- Eval_Logical_Op --
2755 ---------------------
2757 -- Logical operations are static functions, so the result is potentially
2758 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2760 procedure Eval_Logical_Op
(N
: Node_Id
) is
2761 Left
: constant Node_Id
:= Left_Opnd
(N
);
2762 Right
: constant Node_Id
:= Right_Opnd
(N
);
2767 -- If not foldable we are done
2769 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2775 -- Compile time evaluation of logical operation
2778 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2779 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2782 if Is_Modular_Integer_Type
(Etype
(N
)) then
2784 Left_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2785 Right_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2788 To_Bits
(Left_Int
, Left_Bits
);
2789 To_Bits
(Right_Int
, Right_Bits
);
2791 -- Note: should really be able to use array ops instead of
2792 -- these loops, but they weren't working at the time ???
2794 if Nkind
(N
) = N_Op_And
then
2795 for J
in Left_Bits
'Range loop
2796 Left_Bits
(J
) := Left_Bits
(J
) and Right_Bits
(J
);
2799 elsif Nkind
(N
) = N_Op_Or
then
2800 for J
in Left_Bits
'Range loop
2801 Left_Bits
(J
) := Left_Bits
(J
) or Right_Bits
(J
);
2805 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2807 for J
in Left_Bits
'Range loop
2808 Left_Bits
(J
) := Left_Bits
(J
) xor Right_Bits
(J
);
2812 Fold_Uint
(N
, From_Bits
(Left_Bits
, Etype
(N
)), Stat
);
2816 pragma Assert
(Is_Boolean_Type
(Etype
(N
)));
2818 if Nkind
(N
) = N_Op_And
then
2820 Test
(Is_True
(Left_Int
) and then Is_True
(Right_Int
)), Stat
);
2822 elsif Nkind
(N
) = N_Op_Or
then
2824 Test
(Is_True
(Left_Int
) or else Is_True
(Right_Int
)), Stat
);
2827 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2829 Test
(Is_True
(Left_Int
) xor Is_True
(Right_Int
)), Stat
);
2833 end Eval_Logical_Op
;
2835 ------------------------
2836 -- Eval_Membership_Op --
2837 ------------------------
2839 -- A membership test is potentially static if the expression is static, and
2840 -- the range is a potentially static range, or is a subtype mark denoting a
2841 -- static subtype (RM 4.9(12)).
2843 procedure Eval_Membership_Op
(N
: Node_Id
) is
2844 Alts
: constant List_Id
:= Alternatives
(N
);
2845 Choice
: constant Node_Id
:= Right_Opnd
(N
);
2846 Expr
: constant Node_Id
:= Left_Opnd
(N
);
2847 Result
: Match_Result
;
2850 -- Ignore if error in either operand, except to make sure that Any_Type
2851 -- is properly propagated to avoid junk cascaded errors.
2853 if Etype
(Expr
) = Any_Type
2854 or else (Present
(Choice
) and then Etype
(Choice
) = Any_Type
)
2856 Set_Etype
(N
, Any_Type
);
2860 -- If left operand non-static, then nothing to do
2862 if not Is_Static_Expression
(Expr
) then
2866 -- If choice is non-static, left operand is in non-static context
2868 if (Present
(Choice
) and then not Is_Static_Choice
(Choice
))
2869 or else (Present
(Alts
) and then not Is_Static_Choice_List
(Alts
))
2871 Check_Non_Static_Context
(Expr
);
2875 -- Otherwise we definitely have a static expression
2877 Set_Is_Static_Expression
(N
);
2879 -- If left operand raises Constraint_Error, propagate and we are done
2881 if Raises_Constraint_Error
(Expr
) then
2882 Set_Raises_Constraint_Error
(N
, True);
2887 if Present
(Choice
) then
2888 Result
:= Choice_Matches
(Expr
, Choice
);
2890 Result
:= Choices_Match
(Expr
, Alts
);
2893 -- If result is Non_Static, it means that we raise Constraint_Error,
2894 -- since we already tested that the operands were themselves static.
2896 if Result
= Non_Static
then
2897 Set_Raises_Constraint_Error
(N
);
2899 -- Otherwise we have our result (flipped if NOT IN case)
2903 (N
, Test
((Result
= Match
) xor (Nkind
(N
) = N_Not_In
)), True);
2904 Warn_On_Known_Condition
(N
);
2907 end Eval_Membership_Op
;
2909 ------------------------
2910 -- Eval_Named_Integer --
2911 ------------------------
2913 procedure Eval_Named_Integer
(N
: Node_Id
) is
2916 Expr_Value
(Expression
(Declaration_Node
(Entity
(N
)))), True);
2917 end Eval_Named_Integer
;
2919 ---------------------
2920 -- Eval_Named_Real --
2921 ---------------------
2923 procedure Eval_Named_Real
(N
: Node_Id
) is
2926 Expr_Value_R
(Expression
(Declaration_Node
(Entity
(N
)))), True);
2927 end Eval_Named_Real
;
2933 -- Exponentiation is a static functions, so the result is potentially
2934 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2936 procedure Eval_Op_Expon
(N
: Node_Id
) is
2937 Left
: constant Node_Id
:= Left_Opnd
(N
);
2938 Right
: constant Node_Id
:= Right_Opnd
(N
);
2943 -- If not foldable we are done
2945 Test_Expression_Is_Foldable
2946 (N
, Left
, Right
, Stat
, Fold
, CRT_Safe
=> True);
2948 -- Return if not foldable
2954 if Configurable_Run_Time_Mode
and not Stat
then
2958 -- Fold exponentiation operation
2961 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2966 if Is_Integer_Type
(Etype
(Left
)) then
2968 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2972 -- Exponentiation of an integer raises Constraint_Error for a
2973 -- negative exponent (RM 4.5.6).
2975 if Right_Int
< 0 then
2976 Apply_Compile_Time_Constraint_Error
2977 (N
, "integer exponent negative", CE_Range_Check_Failed
,
2982 if OK_Bits
(N
, Num_Bits
(Left_Int
) * Right_Int
) then
2983 Result
:= Left_Int
** Right_Int
;
2988 if Is_Modular_Integer_Type
(Etype
(N
)) then
2989 Result
:= Result
mod Modulus
(Etype
(N
));
2992 Fold_Uint
(N
, Result
, Stat
);
3000 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
3003 -- Cannot have a zero base with a negative exponent
3005 if UR_Is_Zero
(Left_Real
) then
3007 if Right_Int
< 0 then
3008 Apply_Compile_Time_Constraint_Error
3009 (N
, "zero ** negative integer", CE_Range_Check_Failed
,
3013 Fold_Ureal
(N
, Ureal_0
, Stat
);
3017 Fold_Ureal
(N
, Left_Real
** Right_Int
, Stat
);
3028 -- The not operation is a static functions, so the result is potentially
3029 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
3031 procedure Eval_Op_Not
(N
: Node_Id
) is
3032 Right
: constant Node_Id
:= Right_Opnd
(N
);
3037 -- If not foldable we are done
3039 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
3045 -- Fold not operation
3048 Rint
: constant Uint
:= Expr_Value
(Right
);
3049 Typ
: constant Entity_Id
:= Etype
(N
);
3052 -- Negation is equivalent to subtracting from the modulus minus one.
3053 -- For a binary modulus this is equivalent to the ones-complement of
3054 -- the original value. For a nonbinary modulus this is an arbitrary
3055 -- but consistent definition.
3057 if Is_Modular_Integer_Type
(Typ
) then
3058 Fold_Uint
(N
, Modulus
(Typ
) - 1 - Rint
, Stat
);
3059 else pragma Assert
(Is_Boolean_Type
(Typ
));
3060 Fold_Uint
(N
, Test
(not Is_True
(Rint
)), Stat
);
3063 Set_Is_Static_Expression
(N
, Stat
);
3067 -------------------------------
3068 -- Eval_Qualified_Expression --
3069 -------------------------------
3071 -- A qualified expression is potentially static if its subtype mark denotes
3072 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
3074 procedure Eval_Qualified_Expression
(N
: Node_Id
) is
3075 Operand
: constant Node_Id
:= Expression
(N
);
3076 Target_Type
: constant Entity_Id
:= Entity
(Subtype_Mark
(N
));
3083 -- Can only fold if target is string or scalar and subtype is static.
3084 -- Also, do not fold if our parent is an allocator (this is because the
3085 -- qualified expression is really part of the syntactic structure of an
3086 -- allocator, and we do not want to end up with something that
3087 -- corresponds to "new 1" where the 1 is the result of folding a
3088 -- qualified expression).
3090 if not Is_Static_Subtype
(Target_Type
)
3091 or else Nkind
(Parent
(N
)) = N_Allocator
3093 Check_Non_Static_Context
(Operand
);
3095 -- If operand is known to raise constraint_error, set the flag on the
3096 -- expression so it does not get optimized away.
3098 if Nkind
(Operand
) = N_Raise_Constraint_Error
then
3099 Set_Raises_Constraint_Error
(N
);
3105 -- If not foldable we are done
3107 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
3112 -- Don't try fold if target type has Constraint_Error bounds
3114 elsif not Is_OK_Static_Subtype
(Target_Type
) then
3115 Set_Raises_Constraint_Error
(N
);
3119 -- Here we will fold, save Print_In_Hex indication
3121 Hex
:= Nkind
(Operand
) = N_Integer_Literal
3122 and then Print_In_Hex
(Operand
);
3124 -- Fold the result of qualification
3126 if Is_Discrete_Type
(Target_Type
) then
3127 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
3129 -- Preserve Print_In_Hex indication
3131 if Hex
and then Nkind
(N
) = N_Integer_Literal
then
3132 Set_Print_In_Hex
(N
);
3135 elsif Is_Real_Type
(Target_Type
) then
3136 Fold_Ureal
(N
, Expr_Value_R
(Operand
), Stat
);
3139 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Stat
);
3142 Set_Is_Static_Expression
(N
, False);
3144 Check_String_Literal_Length
(N
, Target_Type
);
3150 -- The expression may be foldable but not static
3152 Set_Is_Static_Expression
(N
, Stat
);
3154 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
3157 end Eval_Qualified_Expression
;
3159 -----------------------
3160 -- Eval_Real_Literal --
3161 -----------------------
3163 -- Numeric literals are static (RM 4.9(1)), and have already been marked
3164 -- as static by the analyzer. The reason we did it that early is to allow
3165 -- the possibility of turning off the Is_Static_Expression flag after
3166 -- analysis, but before resolution, when integer literals are generated
3167 -- in the expander that do not correspond to static expressions.
3169 procedure Eval_Real_Literal
(N
: Node_Id
) is
3170 PK
: constant Node_Kind
:= Nkind
(Parent
(N
));
3173 -- If the literal appears in a non-expression context and not as part of
3174 -- a number declaration, then it is appearing in a non-static context,
3177 if PK
not in N_Subexpr
and then PK
/= N_Number_Declaration
then
3178 Check_Non_Static_Context
(N
);
3180 end Eval_Real_Literal
;
3182 ------------------------
3183 -- Eval_Relational_Op --
3184 ------------------------
3186 -- Relational operations are static functions, so the result is static if
3187 -- both operands are static (RM 4.9(7), 4.9(20)), except that for strings,
3188 -- the result is never static, even if the operands are.
3190 -- However, for internally generated nodes, we allow string equality and
3191 -- inequality to be static. This is because we rewrite A in "ABC" as an
3192 -- equality test A = "ABC", and the former is definitely static.
3194 procedure Eval_Relational_Op
(N
: Node_Id
) is
3195 Left
: constant Node_Id
:= Left_Opnd
(N
);
3196 Right
: constant Node_Id
:= Right_Opnd
(N
);
3198 procedure Decompose_Expr
3200 Ent
: out Entity_Id
;
3201 Kind
: out Character;
3203 Orig
: Boolean := True);
3204 -- Given expression Expr, see if it is of the form X [+/- K]. If so, Ent
3205 -- is set to the entity in X, Kind is 'F','L','E' for 'First or 'Last or
3206 -- simple entity, and Cons is the value of K. If the expression is not
3207 -- of the required form, Ent is set to Empty.
3209 -- Orig indicates whether Expr is the original expression to consider,
3210 -- or if we are handling a subexpression (e.g. recursive call to
3213 procedure Fold_General_Op
(Is_Static
: Boolean);
3214 -- Attempt to fold arbitrary relational operator N. Flag Is_Static must
3215 -- be set when the operator denotes a static expression.
3217 procedure Fold_Static_Real_Op
;
3218 -- Attempt to fold static real type relational operator N
3220 function Static_Length
(Expr
: Node_Id
) return Uint
;
3221 -- If Expr is an expression for a constrained array whose length is
3222 -- known at compile time, return the non-negative length, otherwise
3225 --------------------
3226 -- Decompose_Expr --
3227 --------------------
3229 procedure Decompose_Expr
3231 Ent
: out Entity_Id
;
3232 Kind
: out Character;
3234 Orig
: Boolean := True)
3239 -- Assume that the expression does not meet the expected form
3245 if Nkind
(Expr
) = N_Op_Add
3246 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
3248 Exp
:= Left_Opnd
(Expr
);
3249 Cons
:= Expr_Value
(Right_Opnd
(Expr
));
3251 elsif Nkind
(Expr
) = N_Op_Subtract
3252 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
3254 Exp
:= Left_Opnd
(Expr
);
3255 Cons
:= -Expr_Value
(Right_Opnd
(Expr
));
3257 -- If the bound is a constant created to remove side effects, recover
3258 -- the original expression to see if it has one of the recognizable
3261 elsif Nkind
(Expr
) = N_Identifier
3262 and then not Comes_From_Source
(Entity
(Expr
))
3263 and then Ekind
(Entity
(Expr
)) = E_Constant
3264 and then Nkind
(Parent
(Entity
(Expr
))) = N_Object_Declaration
3266 Exp
:= Expression
(Parent
(Entity
(Expr
)));
3267 Decompose_Expr
(Exp
, Ent
, Kind
, Cons
, Orig
=> False);
3269 -- If original expression includes an entity, create a reference
3270 -- to it for use below.
3272 if Present
(Ent
) then
3273 Exp
:= New_Occurrence_Of
(Ent
, Sloc
(Ent
));
3279 -- Only consider the case of X + 0 for a full expression, and
3280 -- not when recursing, otherwise we may end up with evaluating
3281 -- expressions not known at compile time to 0.
3291 -- At this stage Exp is set to the potential X
3293 if Nkind
(Exp
) = N_Attribute_Reference
then
3294 if Attribute_Name
(Exp
) = Name_First
then
3296 elsif Attribute_Name
(Exp
) = Name_Last
then
3302 Exp
:= Prefix
(Exp
);
3308 if Is_Entity_Name
(Exp
) and then Present
(Entity
(Exp
)) then
3309 Ent
:= Entity
(Exp
);
3313 ---------------------
3314 -- Fold_General_Op --
3315 ---------------------
3317 procedure Fold_General_Op
(Is_Static
: Boolean) is
3318 CR
: constant Compare_Result
:=
3319 Compile_Time_Compare
(Left
, Right
, Assume_Valid
=> False);
3324 if CR
= Unknown
then
3332 elsif CR
= NE
or else CR
= GT
or else CR
= LT
then
3339 if CR
= GT
or else CR
= EQ
or else CR
= GE
then
3350 elsif CR
= EQ
or else CR
= LT
or else CR
= LE
then
3357 if CR
= LT
or else CR
= EQ
or else CR
= LE
then
3368 elsif CR
= EQ
or else CR
= GT
or else CR
= GE
then
3375 if CR
= NE
or else CR
= GT
or else CR
= LT
then
3384 raise Program_Error
;
3387 -- Determine the potential outcome of the relation assuming the
3388 -- operands are valid and emit a warning when the relation yields
3389 -- True or False only in the presence of invalid values.
3391 Warn_On_Constant_Valid_Condition
(N
);
3393 Fold_Uint
(N
, Test
(Result
), Is_Static
);
3394 end Fold_General_Op
;
3396 -------------------------
3397 -- Fold_Static_Real_Op --
3398 -------------------------
3400 procedure Fold_Static_Real_Op
is
3401 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
3402 Right_Real
: constant Ureal
:= Expr_Value_R
(Right
);
3407 when N_Op_Eq
=> Result
:= (Left_Real
= Right_Real
);
3408 when N_Op_Ge
=> Result
:= (Left_Real
>= Right_Real
);
3409 when N_Op_Gt
=> Result
:= (Left_Real
> Right_Real
);
3410 when N_Op_Le
=> Result
:= (Left_Real
<= Right_Real
);
3411 when N_Op_Lt
=> Result
:= (Left_Real
< Right_Real
);
3412 when N_Op_Ne
=> Result
:= (Left_Real
/= Right_Real
);
3413 when others => raise Program_Error
;
3416 Fold_Uint
(N
, Test
(Result
), True);
3417 end Fold_Static_Real_Op
;
3423 function Static_Length
(Expr
: Node_Id
) return Uint
is
3433 -- First easy case string literal
3435 if Nkind
(Expr
) = N_String_Literal
then
3436 return UI_From_Int
(String_Length
(Strval
(Expr
)));
3438 -- With frontend inlining as performed in GNATprove mode, a variable
3439 -- may be inserted that has a string literal subtype. Deal with this
3440 -- specially as for the previous case.
3442 elsif Ekind
(Etype
(Expr
)) = E_String_Literal_Subtype
then
3443 return String_Literal_Length
(Etype
(Expr
));
3445 -- Second easy case, not constrained subtype, so no length
3447 elsif not Is_Constrained
(Etype
(Expr
)) then
3448 return Uint_Minus_1
;
3453 Typ
:= Etype
(First_Index
(Etype
(Expr
)));
3455 -- The simple case, both bounds are known at compile time
3457 if Is_Discrete_Type
(Typ
)
3458 and then Compile_Time_Known_Value
(Type_Low_Bound
(Typ
))
3459 and then Compile_Time_Known_Value
(Type_High_Bound
(Typ
))
3462 UI_Max
(Uint_0
, Expr_Value
(Type_High_Bound
(Typ
)) -
3463 Expr_Value
(Type_Low_Bound
(Typ
)) + 1);
3466 -- A more complex case, where the bounds are of the form X [+/- K1]
3467 -- .. X [+/- K2]), where X is an expression that is either A'First or
3468 -- A'Last (with A an entity name), or X is an entity name, and the
3469 -- two X's are the same and K1 and K2 are known at compile time, in
3470 -- this case, the length can also be computed at compile time, even
3471 -- though the bounds are not known. A common case of this is e.g.
3472 -- (X'First .. X'First+5).
3475 (Original_Node
(Type_Low_Bound
(Typ
)), Ent1
, Kind1
, Cons1
);
3477 (Original_Node
(Type_High_Bound
(Typ
)), Ent2
, Kind2
, Cons2
);
3479 if Present
(Ent1
) and then Ent1
= Ent2
and then Kind1
= Kind2
then
3480 return Cons2
- Cons1
+ 1;
3482 return Uint_Minus_1
;
3488 Left_Typ
: constant Entity_Id
:= Etype
(Left
);
3489 Right_Typ
: constant Entity_Id
:= Etype
(Right
);
3492 Op_Typ
: Entity_Id
:= Empty
;
3495 Is_Static_Expression
: Boolean;
3497 -- Start of processing for Eval_Relational_Op
3500 -- One special case to deal with first. If we can tell that the result
3501 -- will be false because the lengths of one or more index subtypes are
3502 -- compile-time known and different, then we can replace the entire
3503 -- result by False. We only do this for one-dimensional arrays, because
3504 -- the case of multidimensional arrays is rare and too much trouble. If
3505 -- one of the operands is an illegal aggregate, its type might still be
3506 -- an arbitrary composite type, so nothing to do.
3508 if Is_Array_Type
(Left_Typ
)
3509 and then Left_Typ
/= Any_Composite
3510 and then Number_Dimensions
(Left_Typ
) = 1
3511 and then Nkind_In
(N
, N_Op_Eq
, N_Op_Ne
)
3513 if Raises_Constraint_Error
(Left
)
3515 Raises_Constraint_Error
(Right
)
3519 -- OK, we have the case where we may be able to do this fold
3522 Left_Len
:= Static_Length
(Left
);
3523 Right_Len
:= Static_Length
(Right
);
3525 if Left_Len
/= Uint_Minus_1
3526 and then Right_Len
/= Uint_Minus_1
3527 and then Left_Len
/= Right_Len
3529 Fold_Uint
(N
, Test
(Nkind
(N
) = N_Op_Ne
), False);
3530 Warn_On_Known_Condition
(N
);
3538 -- Initialize the value of Is_Static_Expression. The value of Fold
3539 -- returned by Test_Expression_Is_Foldable is not needed since, even
3540 -- when some operand is a variable, we can still perform the static
3541 -- evaluation of the expression in some cases (for example, for a
3542 -- variable of a subtype of Integer we statically know that any value
3543 -- stored in such variable is smaller than Integer'Last).
3545 Test_Expression_Is_Foldable
3546 (N
, Left
, Right
, Is_Static_Expression
, Fold
);
3548 -- Only comparisons of scalars can give static results. A comparison
3549 -- of strings never yields a static result, even if both operands are
3550 -- static strings, except that as noted above, we allow equality and
3551 -- inequality for strings.
3553 if Is_String_Type
(Left_Typ
)
3554 and then not Comes_From_Source
(N
)
3555 and then Nkind_In
(N
, N_Op_Eq
, N_Op_Ne
)
3559 elsif not Is_Scalar_Type
(Left_Typ
) then
3560 Is_Static_Expression
:= False;
3561 Set_Is_Static_Expression
(N
, False);
3564 -- For operators on universal numeric types called as functions with
3565 -- an explicit scope, determine appropriate specific numeric type,
3566 -- and diagnose possible ambiguity.
3568 if Is_Universal_Numeric_Type
(Left_Typ
)
3570 Is_Universal_Numeric_Type
(Right_Typ
)
3572 Op_Typ
:= Find_Universal_Operator_Type
(N
);
3575 -- Attempt to fold the relational operator
3577 if Is_Static_Expression
and then Is_Real_Type
(Left_Typ
) then
3578 Fold_Static_Real_Op
;
3580 Fold_General_Op
(Is_Static_Expression
);
3584 -- For the case of a folded relational operator on a specific numeric
3585 -- type, freeze the operand type now.
3587 if Present
(Op_Typ
) then
3588 Freeze_Before
(N
, Op_Typ
);
3591 Warn_On_Known_Condition
(N
);
3592 end Eval_Relational_Op
;
3598 -- Shift operations are intrinsic operations that can never be static, so
3599 -- the only processing required is to perform the required check for a non
3600 -- static context for the two operands.
3602 -- Actually we could do some compile time evaluation here some time ???
3604 procedure Eval_Shift
(N
: Node_Id
) is
3606 Check_Non_Static_Context
(Left_Opnd
(N
));
3607 Check_Non_Static_Context
(Right_Opnd
(N
));
3610 ------------------------
3611 -- Eval_Short_Circuit --
3612 ------------------------
3614 -- A short circuit operation is potentially static if both operands are
3615 -- potentially static (RM 4.9 (13)).
3617 procedure Eval_Short_Circuit
(N
: Node_Id
) is
3618 Kind
: constant Node_Kind
:= Nkind
(N
);
3619 Left
: constant Node_Id
:= Left_Opnd
(N
);
3620 Right
: constant Node_Id
:= Right_Opnd
(N
);
3623 Rstat
: constant Boolean :=
3624 Is_Static_Expression
(Left
)
3626 Is_Static_Expression
(Right
);
3629 -- Short circuit operations are never static in Ada 83
3631 if Ada_Version
= Ada_83
and then Comes_From_Source
(N
) then
3632 Check_Non_Static_Context
(Left
);
3633 Check_Non_Static_Context
(Right
);
3637 -- Now look at the operands, we can't quite use the normal call to
3638 -- Test_Expression_Is_Foldable here because short circuit operations
3639 -- are a special case, they can still be foldable, even if the right
3640 -- operand raises Constraint_Error.
3642 -- If either operand is Any_Type, just propagate to result and do not
3643 -- try to fold, this prevents cascaded errors.
3645 if Etype
(Left
) = Any_Type
or else Etype
(Right
) = Any_Type
then
3646 Set_Etype
(N
, Any_Type
);
3649 -- If left operand raises Constraint_Error, then replace node N with
3650 -- the raise Constraint_Error node, and we are obviously not foldable.
3651 -- Is_Static_Expression is set from the two operands in the normal way,
3652 -- and we check the right operand if it is in a non-static context.
3654 elsif Raises_Constraint_Error
(Left
) then
3656 Check_Non_Static_Context
(Right
);
3659 Rewrite_In_Raise_CE
(N
, Left
);
3660 Set_Is_Static_Expression
(N
, Rstat
);
3663 -- If the result is not static, then we won't in any case fold
3665 elsif not Rstat
then
3666 Check_Non_Static_Context
(Left
);
3667 Check_Non_Static_Context
(Right
);
3671 -- Here the result is static, note that, unlike the normal processing
3672 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
3673 -- the right operand raises Constraint_Error, that's because it is not
3674 -- significant if the left operand is decisive.
3676 Set_Is_Static_Expression
(N
);
3678 -- It does not matter if the right operand raises Constraint_Error if
3679 -- it will not be evaluated. So deal specially with the cases where
3680 -- the right operand is not evaluated. Note that we will fold these
3681 -- cases even if the right operand is non-static, which is fine, but
3682 -- of course in these cases the result is not potentially static.
3684 Left_Int
:= Expr_Value
(Left
);
3686 if (Kind
= N_And_Then
and then Is_False
(Left_Int
))
3688 (Kind
= N_Or_Else
and then Is_True
(Left_Int
))
3690 Fold_Uint
(N
, Left_Int
, Rstat
);
3694 -- If first operand not decisive, then it does matter if the right
3695 -- operand raises Constraint_Error, since it will be evaluated, so
3696 -- we simply replace the node with the right operand. Note that this
3697 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
3698 -- (both are set to True in Right).
3700 if Raises_Constraint_Error
(Right
) then
3701 Rewrite_In_Raise_CE
(N
, Right
);
3702 Check_Non_Static_Context
(Left
);
3706 -- Otherwise the result depends on the right operand
3708 Fold_Uint
(N
, Expr_Value
(Right
), Rstat
);
3710 end Eval_Short_Circuit
;
3716 -- Slices can never be static, so the only processing required is to check
3717 -- for non-static context if an explicit range is given.
3719 procedure Eval_Slice
(N
: Node_Id
) is
3720 Drange
: constant Node_Id
:= Discrete_Range
(N
);
3723 if Nkind
(Drange
) = N_Range
then
3724 Check_Non_Static_Context
(Low_Bound
(Drange
));
3725 Check_Non_Static_Context
(High_Bound
(Drange
));
3728 -- A slice of the form A (subtype), when the subtype is the index of
3729 -- the type of A, is redundant, the slice can be replaced with A, and
3730 -- this is worth a warning.
3732 if Is_Entity_Name
(Prefix
(N
)) then
3734 E
: constant Entity_Id
:= Entity
(Prefix
(N
));
3735 T
: constant Entity_Id
:= Etype
(E
);
3738 if Ekind
(E
) = E_Constant
3739 and then Is_Array_Type
(T
)
3740 and then Is_Entity_Name
(Drange
)
3742 if Is_Entity_Name
(Original_Node
(First_Index
(T
)))
3743 and then Entity
(Original_Node
(First_Index
(T
)))
3746 if Warn_On_Redundant_Constructs
then
3747 Error_Msg_N
("redundant slice denotes whole array?r?", N
);
3750 -- The following might be a useful optimization???
3752 -- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
3759 -------------------------
3760 -- Eval_String_Literal --
3761 -------------------------
3763 procedure Eval_String_Literal
(N
: Node_Id
) is
3764 Typ
: constant Entity_Id
:= Etype
(N
);
3765 Bas
: constant Entity_Id
:= Base_Type
(Typ
);
3771 -- Nothing to do if error type (handles cases like default expressions
3772 -- or generics where we have not yet fully resolved the type).
3774 if Bas
= Any_Type
or else Bas
= Any_String
then
3778 -- String literals are static if the subtype is static (RM 4.9(2)), so
3779 -- reset the static expression flag (it was set unconditionally in
3780 -- Analyze_String_Literal) if the subtype is non-static. We tell if
3781 -- the subtype is static by looking at the lower bound.
3783 if Ekind
(Typ
) = E_String_Literal_Subtype
then
3784 if not Is_OK_Static_Expression
(String_Literal_Low_Bound
(Typ
)) then
3785 Set_Is_Static_Expression
(N
, False);
3789 -- Here if Etype of string literal is normal Etype (not yet possible,
3790 -- but may be possible in future).
3792 elsif not Is_OK_Static_Expression
3793 (Type_Low_Bound
(Etype
(First_Index
(Typ
))))
3795 Set_Is_Static_Expression
(N
, False);
3799 -- If original node was a type conversion, then result if non-static
3801 if Nkind
(Original_Node
(N
)) = N_Type_Conversion
then
3802 Set_Is_Static_Expression
(N
, False);
3806 -- Test for illegal Ada 95 cases. A string literal is illegal in Ada 95
3807 -- if its bounds are outside the index base type and this index type is
3808 -- static. This can happen in only two ways. Either the string literal
3809 -- is too long, or it is null, and the lower bound is type'First. Either
3810 -- way it is the upper bound that is out of range of the index type.
3812 if Ada_Version
>= Ada_95
then
3813 if Is_Standard_String_Type
(Bas
) then
3814 Xtp
:= Standard_Positive
;
3816 Xtp
:= Etype
(First_Index
(Bas
));
3819 if Ekind
(Typ
) = E_String_Literal_Subtype
then
3820 Lo
:= String_Literal_Low_Bound
(Typ
);
3822 Lo
:= Type_Low_Bound
(Etype
(First_Index
(Typ
)));
3825 -- Check for string too long
3827 Len
:= String_Length
(Strval
(N
));
3829 if UI_From_Int
(Len
) > String_Type_Len
(Bas
) then
3831 -- Issue message. Note that this message is a warning if the
3832 -- string literal is not marked as static (happens in some cases
3833 -- of folding strings known at compile time, but not static).
3834 -- Furthermore in such cases, we reword the message, since there
3835 -- is no string literal in the source program.
3837 if Is_Static_Expression
(N
) then
3838 Apply_Compile_Time_Constraint_Error
3839 (N
, "string literal too long for}", CE_Length_Check_Failed
,
3841 Typ
=> First_Subtype
(Bas
));
3843 Apply_Compile_Time_Constraint_Error
3844 (N
, "string value too long for}", CE_Length_Check_Failed
,
3846 Typ
=> First_Subtype
(Bas
),
3850 -- Test for null string not allowed
3853 and then not Is_Generic_Type
(Xtp
)
3855 Expr_Value
(Lo
) = Expr_Value
(Type_Low_Bound
(Base_Type
(Xtp
)))
3857 -- Same specialization of message
3859 if Is_Static_Expression
(N
) then
3860 Apply_Compile_Time_Constraint_Error
3861 (N
, "null string literal not allowed for}",
3862 CE_Length_Check_Failed
,
3864 Typ
=> First_Subtype
(Bas
));
3866 Apply_Compile_Time_Constraint_Error
3867 (N
, "null string value not allowed for}",
3868 CE_Length_Check_Failed
,
3870 Typ
=> First_Subtype
(Bas
),
3875 end Eval_String_Literal
;
3877 --------------------------
3878 -- Eval_Type_Conversion --
3879 --------------------------
3881 -- A type conversion is potentially static if its subtype mark is for a
3882 -- static scalar subtype, and its operand expression is potentially static
3885 procedure Eval_Type_Conversion
(N
: Node_Id
) is
3886 Operand
: constant Node_Id
:= Expression
(N
);
3887 Source_Type
: constant Entity_Id
:= Etype
(Operand
);
3888 Target_Type
: constant Entity_Id
:= Etype
(N
);
3890 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean;
3891 -- Returns true if type T is an integer type, or if it is a fixed-point
3892 -- type to be treated as an integer (i.e. the flag Conversion_OK is set
3893 -- on the conversion node).
3895 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean;
3896 -- Returns true if type T is a floating-point type, or if it is a
3897 -- fixed-point type that is not to be treated as an integer (i.e. the
3898 -- flag Conversion_OK is not set on the conversion node).
3900 ------------------------------
3901 -- To_Be_Treated_As_Integer --
3902 ------------------------------
3904 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean is
3908 or else (Is_Fixed_Point_Type
(T
) and then Conversion_OK
(N
));
3909 end To_Be_Treated_As_Integer
;
3911 ---------------------------
3912 -- To_Be_Treated_As_Real --
3913 ---------------------------
3915 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean is
3918 Is_Floating_Point_Type
(T
)
3919 or else (Is_Fixed_Point_Type
(T
) and then not Conversion_OK
(N
));
3920 end To_Be_Treated_As_Real
;
3927 -- Start of processing for Eval_Type_Conversion
3930 -- Cannot fold if target type is non-static or if semantic error
3932 if not Is_Static_Subtype
(Target_Type
) then
3933 Check_Non_Static_Context
(Operand
);
3935 elsif Error_Posted
(N
) then
3939 -- If not foldable we are done
3941 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
3946 -- Don't try fold if target type has Constraint_Error bounds
3948 elsif not Is_OK_Static_Subtype
(Target_Type
) then
3949 Set_Raises_Constraint_Error
(N
);
3953 -- Remaining processing depends on operand types. Note that in the
3954 -- following type test, fixed-point counts as real unless the flag
3955 -- Conversion_OK is set, in which case it counts as integer.
3957 -- Fold conversion, case of string type. The result is not static
3959 if Is_String_Type
(Target_Type
) then
3960 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Static
=> False);
3963 -- Fold conversion, case of integer target type
3965 elsif To_Be_Treated_As_Integer
(Target_Type
) then
3970 -- Integer to integer conversion
3972 if To_Be_Treated_As_Integer
(Source_Type
) then
3973 Result
:= Expr_Value
(Operand
);
3975 -- Real to integer conversion
3978 Result
:= UR_To_Uint
(Expr_Value_R
(Operand
));
3981 -- If fixed-point type (Conversion_OK must be set), then the
3982 -- result is logically an integer, but we must replace the
3983 -- conversion with the corresponding real literal, since the
3984 -- type from a semantic point of view is still fixed-point.
3986 if Is_Fixed_Point_Type
(Target_Type
) then
3988 (N
, UR_From_Uint
(Result
) * Small_Value
(Target_Type
), Stat
);
3990 -- Otherwise result is integer literal
3993 Fold_Uint
(N
, Result
, Stat
);
3997 -- Fold conversion, case of real target type
3999 elsif To_Be_Treated_As_Real
(Target_Type
) then
4004 if To_Be_Treated_As_Real
(Source_Type
) then
4005 Result
:= Expr_Value_R
(Operand
);
4007 Result
:= UR_From_Uint
(Expr_Value
(Operand
));
4010 Fold_Ureal
(N
, Result
, Stat
);
4013 -- Enumeration types
4016 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
4019 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
4023 end Eval_Type_Conversion
;
4029 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
4030 -- are potentially static if the operand is potentially static (RM 4.9(7)).
4032 procedure Eval_Unary_Op
(N
: Node_Id
) is
4033 Right
: constant Node_Id
:= Right_Opnd
(N
);
4034 Otype
: Entity_Id
:= Empty
;
4039 -- If not foldable we are done
4041 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
4047 if Etype
(Right
) = Universal_Integer
4049 Etype
(Right
) = Universal_Real
4051 Otype
:= Find_Universal_Operator_Type
(N
);
4054 -- Fold for integer case
4056 if Is_Integer_Type
(Etype
(N
)) then
4058 Rint
: constant Uint
:= Expr_Value
(Right
);
4062 -- In the case of modular unary plus and abs there is no need
4063 -- to adjust the result of the operation since if the original
4064 -- operand was in bounds the result will be in the bounds of the
4065 -- modular type. However, in the case of modular unary minus the
4066 -- result may go out of the bounds of the modular type and needs
4069 if Nkind
(N
) = N_Op_Plus
then
4072 elsif Nkind
(N
) = N_Op_Minus
then
4073 if Is_Modular_Integer_Type
(Etype
(N
)) then
4074 Result
:= (-Rint
) mod Modulus
(Etype
(N
));
4080 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
4084 Fold_Uint
(N
, Result
, Stat
);
4087 -- Fold for real case
4089 elsif Is_Real_Type
(Etype
(N
)) then
4091 Rreal
: constant Ureal
:= Expr_Value_R
(Right
);
4095 if Nkind
(N
) = N_Op_Plus
then
4097 elsif Nkind
(N
) = N_Op_Minus
then
4098 Result
:= UR_Negate
(Rreal
);
4100 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
4101 Result
:= abs Rreal
;
4104 Fold_Ureal
(N
, Result
, Stat
);
4108 -- If the operator was resolved to a specific type, make sure that type
4109 -- is frozen even if the expression is folded into a literal (which has
4110 -- a universal type).
4112 if Present
(Otype
) then
4113 Freeze_Before
(N
, Otype
);
4117 -------------------------------
4118 -- Eval_Unchecked_Conversion --
4119 -------------------------------
4121 -- Unchecked conversions can never be static, so the only required
4122 -- processing is to check for a non-static context for the operand.
4124 procedure Eval_Unchecked_Conversion
(N
: Node_Id
) is
4126 Check_Non_Static_Context
(Expression
(N
));
4127 end Eval_Unchecked_Conversion
;
4129 --------------------
4130 -- Expr_Rep_Value --
4131 --------------------
4133 function Expr_Rep_Value
(N
: Node_Id
) return Uint
is
4134 Kind
: constant Node_Kind
:= Nkind
(N
);
4138 if Is_Entity_Name
(N
) then
4141 -- An enumeration literal that was either in the source or created
4142 -- as a result of static evaluation.
4144 if Ekind
(Ent
) = E_Enumeration_Literal
then
4145 return Enumeration_Rep
(Ent
);
4147 -- A user defined static constant
4150 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4151 return Expr_Rep_Value
(Constant_Value
(Ent
));
4154 -- An integer literal that was either in the source or created as a
4155 -- result of static evaluation.
4157 elsif Kind
= N_Integer_Literal
then
4160 -- A real literal for a fixed-point type. This must be the fixed-point
4161 -- case, either the literal is of a fixed-point type, or it is a bound
4162 -- of a fixed-point type, with type universal real. In either case we
4163 -- obtain the desired value from Corresponding_Integer_Value.
4165 elsif Kind
= N_Real_Literal
then
4166 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
4167 return Corresponding_Integer_Value
(N
);
4169 -- Otherwise must be character literal
4172 pragma Assert
(Kind
= N_Character_Literal
);
4175 -- Since Character literals of type Standard.Character don't have any
4176 -- defining character literals built for them, they do not have their
4177 -- Entity set, so just use their Char code. Otherwise for user-
4178 -- defined character literals use their Pos value as usual which is
4179 -- the same as the Rep value.
4182 return Char_Literal_Value
(N
);
4184 return Enumeration_Rep
(Ent
);
4193 function Expr_Value
(N
: Node_Id
) return Uint
is
4194 Kind
: constant Node_Kind
:= Nkind
(N
);
4195 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(N
) mod CV_Cache_Size
);
4200 -- If already in cache, then we know it's compile-time-known and we can
4201 -- return the value that was previously stored in the cache since
4202 -- compile-time-known values cannot change.
4204 if CV_Ent
.N
= N
then
4208 -- Otherwise proceed to test value
4210 if Is_Entity_Name
(N
) then
4213 -- An enumeration literal that was either in the source or created as
4214 -- a result of static evaluation.
4216 if Ekind
(Ent
) = E_Enumeration_Literal
then
4217 Val
:= Enumeration_Pos
(Ent
);
4219 -- A user defined static constant
4222 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4223 Val
:= Expr_Value
(Constant_Value
(Ent
));
4226 -- An integer literal that was either in the source or created as a
4227 -- result of static evaluation.
4229 elsif Kind
= N_Integer_Literal
then
4232 -- A real literal for a fixed-point type. This must be the fixed-point
4233 -- case, either the literal is of a fixed-point type, or it is a bound
4234 -- of a fixed-point type, with type universal real. In either case we
4235 -- obtain the desired value from Corresponding_Integer_Value.
4237 elsif Kind
= N_Real_Literal
then
4238 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
4239 Val
:= Corresponding_Integer_Value
(N
);
4241 -- The NULL access value
4243 elsif Kind
= N_Null
then
4244 pragma Assert
(Is_Access_Type
(Underlying_Type
(Etype
(N
))));
4247 -- Otherwise must be character literal
4250 pragma Assert
(Kind
= N_Character_Literal
);
4253 -- Since Character literals of type Standard.Character don't
4254 -- have any defining character literals built for them, they
4255 -- do not have their Entity set, so just use their Char
4256 -- code. Otherwise for user-defined character literals use
4257 -- their Pos value as usual.
4260 Val
:= Char_Literal_Value
(N
);
4262 Val
:= Enumeration_Pos
(Ent
);
4266 -- Come here with Val set to value to be returned, set cache
4277 function Expr_Value_E
(N
: Node_Id
) return Entity_Id
is
4278 Ent
: constant Entity_Id
:= Entity
(N
);
4280 if Ekind
(Ent
) = E_Enumeration_Literal
then
4283 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4284 return Expr_Value_E
(Constant_Value
(Ent
));
4292 function Expr_Value_R
(N
: Node_Id
) return Ureal
is
4293 Kind
: constant Node_Kind
:= Nkind
(N
);
4297 if Kind
= N_Real_Literal
then
4300 elsif Kind
= N_Identifier
or else Kind
= N_Expanded_Name
then
4302 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4303 return Expr_Value_R
(Constant_Value
(Ent
));
4305 elsif Kind
= N_Integer_Literal
then
4306 return UR_From_Uint
(Expr_Value
(N
));
4308 -- Here, we have a node that cannot be interpreted as a compile time
4309 -- constant. That is definitely an error.
4312 raise Program_Error
;
4320 function Expr_Value_S
(N
: Node_Id
) return Node_Id
is
4322 if Nkind
(N
) = N_String_Literal
then
4325 pragma Assert
(Ekind
(Entity
(N
)) = E_Constant
);
4326 return Expr_Value_S
(Constant_Value
(Entity
(N
)));
4330 ----------------------------------
4331 -- Find_Universal_Operator_Type --
4332 ----------------------------------
4334 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
is
4335 PN
: constant Node_Id
:= Parent
(N
);
4336 Call
: constant Node_Id
:= Original_Node
(N
);
4337 Is_Int
: constant Boolean := Is_Integer_Type
(Etype
(N
));
4339 Is_Fix
: constant Boolean :=
4340 Nkind
(N
) in N_Binary_Op
4341 and then Nkind
(Right_Opnd
(N
)) /= Nkind
(Left_Opnd
(N
));
4342 -- A mixed-mode operation in this context indicates the presence of
4343 -- fixed-point type in the designated package.
4345 Is_Relational
: constant Boolean := Etype
(N
) = Standard_Boolean
;
4346 -- Case where N is a relational (or membership) operator (else it is an
4349 In_Membership
: constant Boolean :=
4350 Nkind
(PN
) in N_Membership_Test
4352 Nkind
(Right_Opnd
(PN
)) = N_Range
4354 Is_Universal_Numeric_Type
(Etype
(Left_Opnd
(PN
)))
4356 Is_Universal_Numeric_Type
4357 (Etype
(Low_Bound
(Right_Opnd
(PN
))))
4359 Is_Universal_Numeric_Type
4360 (Etype
(High_Bound
(Right_Opnd
(PN
))));
4361 -- Case where N is part of a membership test with a universal range
4365 Typ1
: Entity_Id
:= Empty
;
4368 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean;
4369 -- Check whether one operand is a mixed-mode operation that requires the
4370 -- presence of a fixed-point type. Given that all operands are universal
4371 -- and have been constant-folded, retrieve the original function call.
4373 ---------------------------
4374 -- Is_Mixed_Mode_Operand --
4375 ---------------------------
4377 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean is
4378 Onod
: constant Node_Id
:= Original_Node
(Op
);
4380 return Nkind
(Onod
) = N_Function_Call
4381 and then Present
(Next_Actual
(First_Actual
(Onod
)))
4382 and then Etype
(First_Actual
(Onod
)) /=
4383 Etype
(Next_Actual
(First_Actual
(Onod
)));
4384 end Is_Mixed_Mode_Operand
;
4386 -- Start of processing for Find_Universal_Operator_Type
4389 if Nkind
(Call
) /= N_Function_Call
4390 or else Nkind
(Name
(Call
)) /= N_Expanded_Name
4394 -- There are several cases where the context does not imply the type of
4396 -- - the universal expression appears in a type conversion;
4397 -- - the expression is a relational operator applied to universal
4399 -- - the expression is a membership test with a universal operand
4400 -- and a range with universal bounds.
4402 elsif Nkind
(Parent
(N
)) = N_Type_Conversion
4403 or else Is_Relational
4404 or else In_Membership
4406 Pack
:= Entity
(Prefix
(Name
(Call
)));
4408 -- If the prefix is a package declared elsewhere, iterate over its
4409 -- visible entities, otherwise iterate over all declarations in the
4410 -- designated scope.
4412 if Ekind
(Pack
) = E_Package
4413 and then not In_Open_Scopes
(Pack
)
4415 Priv_E
:= First_Private_Entity
(Pack
);
4421 E
:= First_Entity
(Pack
);
4422 while Present
(E
) and then E
/= Priv_E
loop
4423 if Is_Numeric_Type
(E
)
4424 and then Nkind
(Parent
(E
)) /= N_Subtype_Declaration
4425 and then Comes_From_Source
(E
)
4426 and then Is_Integer_Type
(E
) = Is_Int
4427 and then (Nkind
(N
) in N_Unary_Op
4428 or else Is_Relational
4429 or else Is_Fixed_Point_Type
(E
) = Is_Fix
)
4434 -- Before emitting an error, check for the presence of a
4435 -- mixed-mode operation that specifies a fixed point type.
4439 (Is_Mixed_Mode_Operand
(Left_Opnd
(N
))
4440 or else Is_Mixed_Mode_Operand
(Right_Opnd
(N
)))
4441 and then Is_Fixed_Point_Type
(E
) /= Is_Fixed_Point_Type
(Typ1
)
4444 if Is_Fixed_Point_Type
(E
) then
4449 -- More than one type of the proper class declared in P
4451 Error_Msg_N
("ambiguous operation", N
);
4452 Error_Msg_Sloc
:= Sloc
(Typ1
);
4453 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4454 Error_Msg_Sloc
:= Sloc
(E
);
4455 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4465 end Find_Universal_Operator_Type
;
4467 --------------------------
4468 -- Flag_Non_Static_Expr --
4469 --------------------------
4471 procedure Flag_Non_Static_Expr
(Msg
: String; Expr
: Node_Id
) is
4473 if Error_Posted
(Expr
) and then not All_Errors_Mode
then
4476 Error_Msg_F
(Msg
, Expr
);
4477 Why_Not_Static
(Expr
);
4479 end Flag_Non_Static_Expr
;
4485 procedure Fold_Str
(N
: Node_Id
; Val
: String_Id
; Static
: Boolean) is
4486 Loc
: constant Source_Ptr
:= Sloc
(N
);
4487 Typ
: constant Entity_Id
:= Etype
(N
);
4490 if Raises_Constraint_Error
(N
) then
4491 Set_Is_Static_Expression
(N
, Static
);
4495 Rewrite
(N
, Make_String_Literal
(Loc
, Strval
=> Val
));
4497 -- We now have the literal with the right value, both the actual type
4498 -- and the expected type of this literal are taken from the expression
4499 -- that was evaluated. So now we do the Analyze and Resolve.
4501 -- Note that we have to reset Is_Static_Expression both after the
4502 -- analyze step (because Resolve will evaluate the literal, which
4503 -- will cause semantic errors if it is marked as static), and after
4504 -- the Resolve step (since Resolve in some cases resets this flag).
4507 Set_Is_Static_Expression
(N
, Static
);
4510 Set_Is_Static_Expression
(N
, Static
);
4517 procedure Fold_Uint
(N
: Node_Id
; Val
: Uint
; Static
: Boolean) is
4518 Loc
: constant Source_Ptr
:= Sloc
(N
);
4519 Typ
: Entity_Id
:= Etype
(N
);
4523 if Raises_Constraint_Error
(N
) then
4524 Set_Is_Static_Expression
(N
, Static
);
4528 -- If we are folding a named number, retain the entity in the literal,
4531 if Is_Entity_Name
(N
) and then Ekind
(Entity
(N
)) = E_Named_Integer
then
4537 if Is_Private_Type
(Typ
) then
4538 Typ
:= Full_View
(Typ
);
4541 -- For a result of type integer, substitute an N_Integer_Literal node
4542 -- for the result of the compile time evaluation of the expression.
4543 -- For ASIS use, set a link to the original named number when not in
4544 -- a generic context.
4546 if Is_Integer_Type
(Typ
) then
4547 Rewrite
(N
, Make_Integer_Literal
(Loc
, Val
));
4548 Set_Original_Entity
(N
, Ent
);
4550 -- Otherwise we have an enumeration type, and we substitute either
4551 -- an N_Identifier or N_Character_Literal to represent the enumeration
4552 -- literal corresponding to the given value, which must always be in
4553 -- range, because appropriate tests have already been made for this.
4555 else pragma Assert
(Is_Enumeration_Type
(Typ
));
4556 Rewrite
(N
, Get_Enum_Lit_From_Pos
(Etype
(N
), Val
, Loc
));
4559 -- We now have the literal with the right value, both the actual type
4560 -- and the expected type of this literal are taken from the expression
4561 -- that was evaluated. So now we do the Analyze and Resolve.
4563 -- Note that we have to reset Is_Static_Expression both after the
4564 -- analyze step (because Resolve will evaluate the literal, which
4565 -- will cause semantic errors if it is marked as static), and after
4566 -- the Resolve step (since Resolve in some cases sets this flag).
4569 Set_Is_Static_Expression
(N
, Static
);
4572 Set_Is_Static_Expression
(N
, Static
);
4579 procedure Fold_Ureal
(N
: Node_Id
; Val
: Ureal
; Static
: Boolean) is
4580 Loc
: constant Source_Ptr
:= Sloc
(N
);
4581 Typ
: constant Entity_Id
:= Etype
(N
);
4585 if Raises_Constraint_Error
(N
) then
4586 Set_Is_Static_Expression
(N
, Static
);
4590 -- If we are folding a named number, retain the entity in the literal,
4593 if Is_Entity_Name
(N
) and then Ekind
(Entity
(N
)) = E_Named_Real
then
4599 Rewrite
(N
, Make_Real_Literal
(Loc
, Realval
=> Val
));
4601 -- Set link to original named number, for ASIS use
4603 Set_Original_Entity
(N
, Ent
);
4605 -- We now have the literal with the right value, both the actual type
4606 -- and the expected type of this literal are taken from the expression
4607 -- that was evaluated. So now we do the Analyze and Resolve.
4609 -- Note that we have to reset Is_Static_Expression both after the
4610 -- analyze step (because Resolve will evaluate the literal, which
4611 -- will cause semantic errors if it is marked as static), and after
4612 -- the Resolve step (since Resolve in some cases sets this flag).
4615 Set_Is_Static_Expression
(N
, Static
);
4618 Set_Is_Static_Expression
(N
, Static
);
4625 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
is
4629 for J
in 0 .. B
'Last loop
4635 if Non_Binary_Modulus
(T
) then
4636 V
:= V
mod Modulus
(T
);
4642 --------------------
4643 -- Get_String_Val --
4644 --------------------
4646 function Get_String_Val
(N
: Node_Id
) return Node_Id
is
4648 if Nkind_In
(N
, N_String_Literal
, N_Character_Literal
) then
4651 pragma Assert
(Is_Entity_Name
(N
));
4652 return Get_String_Val
(Constant_Value
(Entity
(N
)));
4660 procedure Initialize
is
4662 CV_Cache
:= (others => (Node_High_Bound
, Uint_0
));
4665 --------------------
4666 -- In_Subrange_Of --
4667 --------------------
4669 function In_Subrange_Of
4672 Fixed_Int
: Boolean := False) return Boolean
4681 if T1
= T2
or else Is_Subtype_Of
(T1
, T2
) then
4684 -- Never in range if both types are not scalar. Don't know if this can
4685 -- actually happen, but just in case.
4687 elsif not Is_Scalar_Type
(T1
) or else not Is_Scalar_Type
(T2
) then
4690 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
4691 -- definitely not compatible with T2.
4693 elsif Is_Floating_Point_Type
(T1
)
4694 and then Has_Infinities
(T1
)
4695 and then Is_Floating_Point_Type
(T2
)
4696 and then not Has_Infinities
(T2
)
4701 L1
:= Type_Low_Bound
(T1
);
4702 H1
:= Type_High_Bound
(T1
);
4704 L2
:= Type_Low_Bound
(T2
);
4705 H2
:= Type_High_Bound
(T2
);
4707 -- Check bounds to see if comparison possible at compile time
4709 if Compile_Time_Compare
(L1
, L2
, Assume_Valid
=> True) in Compare_GE
4711 Compile_Time_Compare
(H1
, H2
, Assume_Valid
=> True) in Compare_LE
4716 -- If bounds not comparable at compile time, then the bounds of T2
4717 -- must be compile-time-known or we cannot answer the query.
4719 if not Compile_Time_Known_Value
(L2
)
4720 or else not Compile_Time_Known_Value
(H2
)
4725 -- If the bounds of T1 are know at compile time then use these
4726 -- ones, otherwise use the bounds of the base type (which are of
4727 -- course always static).
4729 if not Compile_Time_Known_Value
(L1
) then
4730 L1
:= Type_Low_Bound
(Base_Type
(T1
));
4733 if not Compile_Time_Known_Value
(H1
) then
4734 H1
:= Type_High_Bound
(Base_Type
(T1
));
4737 -- Fixed point types should be considered as such only if
4738 -- flag Fixed_Int is set to False.
4740 if Is_Floating_Point_Type
(T1
) or else Is_Floating_Point_Type
(T2
)
4741 or else (Is_Fixed_Point_Type
(T1
) and then not Fixed_Int
)
4742 or else (Is_Fixed_Point_Type
(T2
) and then not Fixed_Int
)
4745 Expr_Value_R
(L2
) <= Expr_Value_R
(L1
)
4747 Expr_Value_R
(H2
) >= Expr_Value_R
(H1
);
4751 Expr_Value
(L2
) <= Expr_Value
(L1
)
4753 Expr_Value
(H2
) >= Expr_Value
(H1
);
4758 -- If any exception occurs, it means that we have some bug in the compiler
4759 -- possibly triggered by a previous error, or by some unforeseen peculiar
4760 -- occurrence. However, this is only an optimization attempt, so there is
4761 -- really no point in crashing the compiler. Instead we just decide, too
4762 -- bad, we can't figure out the answer in this case after all.
4767 -- Debug flag K disables this behavior (useful for debugging)
4769 if Debug_Flag_K
then
4780 function Is_In_Range
4783 Assume_Valid
: Boolean := False;
4784 Fixed_Int
: Boolean := False;
4785 Int_Real
: Boolean := False) return Boolean
4789 Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
) = In_Range
;
4796 function Is_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
4798 if Compile_Time_Known_Value
(Lo
)
4799 and then Compile_Time_Known_Value
(Hi
)
4802 Typ
: Entity_Id
:= Etype
(Lo
);
4804 -- When called from the frontend, as part of the analysis of
4805 -- potentially static expressions, Typ will be the full view of a
4806 -- type with all the info needed to answer this query. When called
4807 -- from the backend, for example to know whether a range of a loop
4808 -- is null, Typ might be a private type and we need to explicitly
4809 -- switch to its corresponding full view to access the same info.
4811 if Is_Incomplete_Or_Private_Type
(Typ
)
4812 and then Present
(Full_View
(Typ
))
4814 Typ
:= Full_View
(Typ
);
4817 if Is_Discrete_Type
(Typ
) then
4818 return Expr_Value
(Lo
) > Expr_Value
(Hi
);
4819 else pragma Assert
(Is_Real_Type
(Typ
));
4820 return Expr_Value_R
(Lo
) > Expr_Value_R
(Hi
);
4828 -------------------------
4829 -- Is_OK_Static_Choice --
4830 -------------------------
4832 function Is_OK_Static_Choice
(Choice
: Node_Id
) return Boolean is
4834 -- Check various possibilities for choice
4836 -- Note: for membership tests, we test more cases than are possible
4837 -- (in particular subtype indication), but it doesn't matter because
4838 -- it just won't occur (we have already done a syntax check).
4840 if Nkind
(Choice
) = N_Others_Choice
then
4843 elsif Nkind
(Choice
) = N_Range
then
4844 return Is_OK_Static_Range
(Choice
);
4846 elsif Nkind
(Choice
) = N_Subtype_Indication
4847 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
4849 return Is_OK_Static_Subtype
(Etype
(Choice
));
4852 return Is_OK_Static_Expression
(Choice
);
4854 end Is_OK_Static_Choice
;
4856 ------------------------------
4857 -- Is_OK_Static_Choice_List --
4858 ------------------------------
4860 function Is_OK_Static_Choice_List
(Choices
: List_Id
) return Boolean is
4864 if not Is_Static_Choice_List
(Choices
) then
4868 Choice
:= First
(Choices
);
4869 while Present
(Choice
) loop
4870 if not Is_OK_Static_Choice
(Choice
) then
4871 Set_Raises_Constraint_Error
(Choice
);
4879 end Is_OK_Static_Choice_List
;
4881 -----------------------------
4882 -- Is_OK_Static_Expression --
4883 -----------------------------
4885 function Is_OK_Static_Expression
(N
: Node_Id
) return Boolean is
4887 return Is_Static_Expression
(N
) and then not Raises_Constraint_Error
(N
);
4888 end Is_OK_Static_Expression
;
4890 ------------------------
4891 -- Is_OK_Static_Range --
4892 ------------------------
4894 -- A static range is a range whose bounds are static expressions, or a
4895 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4896 -- We have already converted range attribute references, so we get the
4897 -- "or" part of this rule without needing a special test.
4899 function Is_OK_Static_Range
(N
: Node_Id
) return Boolean is
4901 return Is_OK_Static_Expression
(Low_Bound
(N
))
4902 and then Is_OK_Static_Expression
(High_Bound
(N
));
4903 end Is_OK_Static_Range
;
4905 --------------------------
4906 -- Is_OK_Static_Subtype --
4907 --------------------------
4909 -- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
4910 -- neither bound raises Constraint_Error when evaluated.
4912 function Is_OK_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
4913 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
4914 Anc_Subt
: Entity_Id
;
4917 -- First a quick check on the non static subtype flag. As described
4918 -- in further detail in Einfo, this flag is not decisive in all cases,
4919 -- but if it is set, then the subtype is definitely non-static.
4921 if Is_Non_Static_Subtype
(Typ
) then
4925 Anc_Subt
:= Ancestor_Subtype
(Typ
);
4927 if Anc_Subt
= Empty
then
4931 if Is_Generic_Type
(Root_Type
(Base_T
))
4932 or else Is_Generic_Actual_Type
(Base_T
)
4936 elsif Has_Dynamic_Predicate_Aspect
(Typ
) then
4941 elsif Is_String_Type
(Typ
) then
4943 Ekind
(Typ
) = E_String_Literal_Subtype
4945 (Is_OK_Static_Subtype
(Component_Type
(Typ
))
4946 and then Is_OK_Static_Subtype
(Etype
(First_Index
(Typ
))));
4950 elsif Is_Scalar_Type
(Typ
) then
4951 if Base_T
= Typ
then
4955 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
4956 -- Get_Type_{Low,High}_Bound.
4958 return Is_OK_Static_Subtype
(Anc_Subt
)
4959 and then Is_OK_Static_Expression
(Type_Low_Bound
(Typ
))
4960 and then Is_OK_Static_Expression
(Type_High_Bound
(Typ
));
4963 -- Types other than string and scalar types are never static
4968 end Is_OK_Static_Subtype
;
4970 ---------------------
4971 -- Is_Out_Of_Range --
4972 ---------------------
4974 function Is_Out_Of_Range
4977 Assume_Valid
: Boolean := False;
4978 Fixed_Int
: Boolean := False;
4979 Int_Real
: Boolean := False) return Boolean
4982 return Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
) =
4984 end Is_Out_Of_Range
;
4986 ----------------------
4987 -- Is_Static_Choice --
4988 ----------------------
4990 function Is_Static_Choice
(Choice
: Node_Id
) return Boolean is
4992 -- Check various possibilities for choice
4994 -- Note: for membership tests, we test more cases than are possible
4995 -- (in particular subtype indication), but it doesn't matter because
4996 -- it just won't occur (we have already done a syntax check).
4998 if Nkind
(Choice
) = N_Others_Choice
then
5001 elsif Nkind
(Choice
) = N_Range
then
5002 return Is_Static_Range
(Choice
);
5004 elsif Nkind
(Choice
) = N_Subtype_Indication
5005 or else (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
5007 return Is_Static_Subtype
(Etype
(Choice
));
5010 return Is_Static_Expression
(Choice
);
5012 end Is_Static_Choice
;
5014 ---------------------------
5015 -- Is_Static_Choice_List --
5016 ---------------------------
5018 function Is_Static_Choice_List
(Choices
: List_Id
) return Boolean is
5022 Choice
:= First
(Choices
);
5023 while Present
(Choice
) loop
5024 if not Is_Static_Choice
(Choice
) then
5032 end Is_Static_Choice_List
;
5034 ---------------------
5035 -- Is_Static_Range --
5036 ---------------------
5038 -- A static range is a range whose bounds are static expressions, or a
5039 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
5040 -- We have already converted range attribute references, so we get the
5041 -- "or" part of this rule without needing a special test.
5043 function Is_Static_Range
(N
: Node_Id
) return Boolean is
5045 return Is_Static_Expression
(Low_Bound
(N
))
5047 Is_Static_Expression
(High_Bound
(N
));
5048 end Is_Static_Range
;
5050 -----------------------
5051 -- Is_Static_Subtype --
5052 -----------------------
5054 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
5056 function Is_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
5057 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
5058 Anc_Subt
: Entity_Id
;
5061 -- First a quick check on the non static subtype flag. As described
5062 -- in further detail in Einfo, this flag is not decisive in all cases,
5063 -- but if it is set, then the subtype is definitely non-static.
5065 if Is_Non_Static_Subtype
(Typ
) then
5069 Anc_Subt
:= Ancestor_Subtype
(Typ
);
5071 if Anc_Subt
= Empty
then
5075 if Is_Generic_Type
(Root_Type
(Base_T
))
5076 or else Is_Generic_Actual_Type
(Base_T
)
5080 -- If there is a dynamic predicate for the type (declared or inherited)
5081 -- the expression is not static.
5083 elsif Has_Dynamic_Predicate_Aspect
(Typ
)
5084 or else (Is_Derived_Type
(Typ
)
5085 and then Has_Aspect
(Typ
, Aspect_Dynamic_Predicate
))
5091 elsif Is_String_Type
(Typ
) then
5093 Ekind
(Typ
) = E_String_Literal_Subtype
5094 or else (Is_Static_Subtype
(Component_Type
(Typ
))
5095 and then Is_Static_Subtype
(Etype
(First_Index
(Typ
))));
5099 elsif Is_Scalar_Type
(Typ
) then
5100 if Base_T
= Typ
then
5104 return Is_Static_Subtype
(Anc_Subt
)
5105 and then Is_Static_Expression
(Type_Low_Bound
(Typ
))
5106 and then Is_Static_Expression
(Type_High_Bound
(Typ
));
5109 -- Types other than string and scalar types are never static
5114 end Is_Static_Subtype
;
5116 -------------------------------
5117 -- Is_Statically_Unevaluated --
5118 -------------------------------
5120 function Is_Statically_Unevaluated
(Expr
: Node_Id
) return Boolean is
5121 function Check_Case_Expr_Alternative
5122 (CEA
: Node_Id
) return Match_Result
;
5123 -- We have a message emanating from the Expression of a case expression
5124 -- alternative. We examine this alternative, as follows:
5126 -- If the selecting expression of the parent case is non-static, or
5127 -- if any of the discrete choices of the given case alternative are
5128 -- non-static or raise Constraint_Error, return Non_Static.
5130 -- Otherwise check if the selecting expression matches any of the given
5131 -- discrete choices. If so, the alternative is executed and we return
5132 -- Match, otherwise, the alternative can never be executed, and so we
5135 ---------------------------------
5136 -- Check_Case_Expr_Alternative --
5137 ---------------------------------
5139 function Check_Case_Expr_Alternative
5140 (CEA
: Node_Id
) return Match_Result
5142 Case_Exp
: constant Node_Id
:= Parent
(CEA
);
5147 pragma Assert
(Nkind
(Case_Exp
) = N_Case_Expression
);
5149 -- Check that selecting expression is static
5151 if not Is_OK_Static_Expression
(Expression
(Case_Exp
)) then
5155 if not Is_OK_Static_Choice_List
(Discrete_Choices
(CEA
)) then
5159 -- All choices are now known to be static. Now see if alternative
5160 -- matches one of the choices.
5162 Choice
:= First
(Discrete_Choices
(CEA
));
5163 while Present
(Choice
) loop
5165 -- Check various possibilities for choice, returning Match if we
5166 -- find the selecting value matches any of the choices. Note that
5167 -- we know we are the last choice, so we don't have to keep going.
5169 if Nkind
(Choice
) = N_Others_Choice
then
5171 -- Others choice is a bit annoying, it matches if none of the
5172 -- previous alternatives matches (note that we know we are the
5173 -- last alternative in this case, so we can just go backwards
5174 -- from us to see if any previous one matches).
5176 Prev_CEA
:= Prev
(CEA
);
5177 while Present
(Prev_CEA
) loop
5178 if Check_Case_Expr_Alternative
(Prev_CEA
) = Match
then
5187 -- Else we have a normal static choice
5189 elsif Choice_Matches
(Expression
(Case_Exp
), Choice
) = Match
then
5193 -- If we fall through, it means that the discrete choice did not
5194 -- match the selecting expression, so continue.
5199 -- If we get through that loop then all choices were static, and none
5200 -- of them matched the selecting expression. So return No_Match.
5203 end Check_Case_Expr_Alternative
;
5211 -- Start of processing for Is_Statically_Unevaluated
5214 -- The (32.x) references here are from RM section 4.9
5216 -- (32.1) An expression is statically unevaluated if it is part of ...
5218 -- This means we have to climb the tree looking for one of the cases
5225 -- (32.2) The right operand of a static short-circuit control form
5226 -- whose value is determined by its left operand.
5228 -- AND THEN with False as left operand
5230 if Nkind
(P
) = N_And_Then
5231 and then Compile_Time_Known_Value
(Left_Opnd
(P
))
5232 and then Is_False
(Expr_Value
(Left_Opnd
(P
)))
5236 -- OR ELSE with True as left operand
5238 elsif Nkind
(P
) = N_Or_Else
5239 and then Compile_Time_Known_Value
(Left_Opnd
(P
))
5240 and then Is_True
(Expr_Value
(Left_Opnd
(P
)))
5244 -- (32.3) A dependent_expression of an if_expression whose associated
5245 -- condition is static and equals False.
5247 elsif Nkind
(P
) = N_If_Expression
then
5249 Cond
: constant Node_Id
:= First
(Expressions
(P
));
5250 Texp
: constant Node_Id
:= Next
(Cond
);
5251 Fexp
: constant Node_Id
:= Next
(Texp
);
5254 if Compile_Time_Known_Value
(Cond
) then
5256 -- Condition is True and we are in the right operand
5258 if Is_True
(Expr_Value
(Cond
)) and then OldP
= Fexp
then
5261 -- Condition is False and we are in the left operand
5263 elsif Is_False
(Expr_Value
(Cond
)) and then OldP
= Texp
then
5269 -- (32.4) A condition or dependent_expression of an if_expression
5270 -- where the condition corresponding to at least one preceding
5271 -- dependent_expression of the if_expression is static and equals
5274 -- This refers to cases like
5276 -- (if True then 1 elsif 1/0=2 then 2 else 3)
5278 -- But we expand elsif's out anyway, so the above looks like:
5280 -- (if True then 1 else (if 1/0=2 then 2 else 3))
5282 -- So for us this is caught by the above check for the 32.3 case.
5284 -- (32.5) A dependent_expression of a case_expression whose
5285 -- selecting_expression is static and whose value is not covered
5286 -- by the corresponding discrete_choice_list.
5288 elsif Nkind
(P
) = N_Case_Expression_Alternative
then
5290 -- First, we have to be in the expression to suppress messages.
5291 -- If we are within one of the choices, we want the message.
5293 if OldP
= Expression
(P
) then
5295 -- Statically unevaluated if alternative does not match
5297 if Check_Case_Expr_Alternative
(P
) = No_Match
then
5302 -- (32.6) A choice_expression (or a simple_expression of a range
5303 -- that occurs as a membership_choice of a membership_choice_list)
5304 -- of a static membership test that is preceded in the enclosing
5305 -- membership_choice_list by another item whose individual
5306 -- membership test (see (RM 4.5.2)) statically yields True.
5308 elsif Nkind
(P
) in N_Membership_Test
then
5310 -- Only possibly unevaluated if simple expression is static
5312 if not Is_OK_Static_Expression
(Left_Opnd
(P
)) then
5315 -- All members of the choice list must be static
5317 elsif (Present
(Right_Opnd
(P
))
5318 and then not Is_OK_Static_Choice
(Right_Opnd
(P
)))
5319 or else (Present
(Alternatives
(P
))
5321 not Is_OK_Static_Choice_List
(Alternatives
(P
)))
5325 -- If expression is the one and only alternative, then it is
5326 -- definitely not statically unevaluated, so we only have to
5327 -- test the case where there are alternatives present.
5329 elsif Present
(Alternatives
(P
)) then
5331 -- Look for previous matching Choice
5333 Choice
:= First
(Alternatives
(P
));
5334 while Present
(Choice
) loop
5336 -- If we reached us and no previous choices matched, this
5337 -- is not the case where we are statically unevaluated.
5339 exit when OldP
= Choice
;
5341 -- If a previous choice matches, then that is the case where
5342 -- we know our choice is statically unevaluated.
5344 if Choice_Matches
(Left_Opnd
(P
), Choice
) = Match
then
5351 -- If we fall through the loop, we were not one of the choices,
5352 -- we must have been the expression, so that is not covered by
5353 -- this rule, and we keep going.
5359 -- OK, not statically unevaluated at this level, see if we should
5360 -- keep climbing to look for a higher level reason.
5362 -- Special case for component association in aggregates, where
5363 -- we want to keep climbing up to the parent aggregate.
5365 if Nkind
(P
) = N_Component_Association
5366 and then Nkind
(Parent
(P
)) = N_Aggregate
5370 -- All done if not still within subexpression
5373 exit when Nkind
(P
) not in N_Subexpr
;
5377 -- If we fall through the loop, not one of the cases covered!
5380 end Is_Statically_Unevaluated
;
5382 --------------------
5383 -- Not_Null_Range --
5384 --------------------
5386 function Not_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
5388 if Compile_Time_Known_Value
(Lo
)
5389 and then Compile_Time_Known_Value
(Hi
)
5392 Typ
: Entity_Id
:= Etype
(Lo
);
5394 -- When called from the frontend, as part of the analysis of
5395 -- potentially static expressions, Typ will be the full view of a
5396 -- type with all the info needed to answer this query. When called
5397 -- from the backend, for example to know whether a range of a loop
5398 -- is null, Typ might be a private type and we need to explicitly
5399 -- switch to its corresponding full view to access the same info.
5401 if Is_Incomplete_Or_Private_Type
(Typ
)
5402 and then Present
(Full_View
(Typ
))
5404 Typ
:= Full_View
(Typ
);
5407 if Is_Discrete_Type
(Typ
) then
5408 return Expr_Value
(Lo
) <= Expr_Value
(Hi
);
5409 else pragma Assert
(Is_Real_Type
(Typ
));
5410 return Expr_Value_R
(Lo
) <= Expr_Value_R
(Hi
);
5423 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean is
5425 -- We allow a maximum of 500,000 bits which seems a reasonable limit
5427 if Bits
< 500_000
then
5430 -- Error if this maximum is exceeded
5433 Error_Msg_N
("static value too large, capacity exceeded", N
);
5442 procedure Out_Of_Range
(N
: Node_Id
) is
5444 -- If we have the static expression case, then this is an illegality
5445 -- in Ada 95 mode, except that in an instance, we never generate an
5446 -- error (if the error is legitimate, it was already diagnosed in the
5449 if Is_Static_Expression
(N
)
5450 and then not In_Instance
5451 and then not In_Inlined_Body
5452 and then Ada_Version
>= Ada_95
5454 -- No message if we are statically unevaluated
5456 if Is_Statically_Unevaluated
(N
) then
5459 -- The expression to compute the length of a packed array is attached
5460 -- to the array type itself, and deserves a separate message.
5462 elsif Nkind
(Parent
(N
)) = N_Defining_Identifier
5463 and then Is_Array_Type
(Parent
(N
))
5464 and then Present
(Packed_Array_Impl_Type
(Parent
(N
)))
5465 and then Present
(First_Rep_Item
(Parent
(N
)))
5468 ("length of packed array must not exceed Integer''Last",
5469 First_Rep_Item
(Parent
(N
)));
5470 Rewrite
(N
, Make_Integer_Literal
(Sloc
(N
), Uint_1
));
5472 -- All cases except the special array case.
5473 -- No message if we are dealing with System.Priority values in
5474 -- CodePeer mode where the target runtime may have more priorities.
5476 elsif not CodePeer_Mode
or else Etype
(N
) /= RTE
(RE_Priority
) then
5477 Apply_Compile_Time_Constraint_Error
5478 (N
, "value not in range of}", CE_Range_Check_Failed
);
5481 -- Here we generate a warning for the Ada 83 case, or when we are in an
5482 -- instance, or when we have a non-static expression case.
5485 Apply_Compile_Time_Constraint_Error
5486 (N
, "value not in range of}??", CE_Range_Check_Failed
);
5490 ----------------------
5491 -- Predicates_Match --
5492 ----------------------
5494 function Predicates_Match
(T1
, T2
: Entity_Id
) return Boolean is
5499 if Ada_Version
< Ada_2012
then
5502 -- Both types must have predicates or lack them
5504 elsif Has_Predicates
(T1
) /= Has_Predicates
(T2
) then
5507 -- Check matching predicates
5512 (T1
, Name_Static_Predicate
, Check_Parents
=> False);
5515 (T2
, Name_Static_Predicate
, Check_Parents
=> False);
5517 -- Subtypes statically match if the predicate comes from the
5518 -- same declaration, which can only happen if one is a subtype
5519 -- of the other and has no explicit predicate.
5521 -- Suppress warnings on order of actuals, which is otherwise
5522 -- triggered by one of the two calls below.
5524 pragma Warnings
(Off
);
5525 return Pred1
= Pred2
5526 or else (No
(Pred1
) and then Is_Subtype_Of
(T1
, T2
))
5527 or else (No
(Pred2
) and then Is_Subtype_Of
(T2
, T1
));
5528 pragma Warnings
(On
);
5530 end Predicates_Match
;
5532 ---------------------------------------------
5533 -- Real_Or_String_Static_Predicate_Matches --
5534 ---------------------------------------------
5536 function Real_Or_String_Static_Predicate_Matches
5538 Typ
: Entity_Id
) return Boolean
5540 Expr
: constant Node_Id
:= Static_Real_Or_String_Predicate
(Typ
);
5541 -- The predicate expression from the type
5543 Pfun
: constant Entity_Id
:= Predicate_Function
(Typ
);
5544 -- The entity for the predicate function
5546 Ent_Name
: constant Name_Id
:= Chars
(First_Formal
(Pfun
));
5547 -- The name of the formal of the predicate function. Occurrences of the
5548 -- type name in Expr have been rewritten as references to this formal,
5549 -- and it has a unique name, so we can identify references by this name.
5552 -- Copy of the predicate function tree
5554 function Process
(N
: Node_Id
) return Traverse_Result
;
5555 -- Function used to process nodes during the traversal in which we will
5556 -- find occurrences of the entity name, and replace such occurrences
5557 -- by a real literal with the value to be tested.
5559 procedure Traverse
is new Traverse_Proc
(Process
);
5560 -- The actual traversal procedure
5566 function Process
(N
: Node_Id
) return Traverse_Result
is
5568 if Nkind
(N
) = N_Identifier
and then Chars
(N
) = Ent_Name
then
5570 Nod
: constant Node_Id
:= New_Copy
(Val
);
5572 Set_Sloc
(Nod
, Sloc
(N
));
5577 -- The predicate function may contain string-comparison operations
5578 -- that have been converted into calls to run-time array-comparison
5579 -- routines. To evaluate the predicate statically, we recover the
5580 -- original comparison operation and replace the occurrence of the
5581 -- formal by the static string value. The actuals of the generated
5582 -- call are of the form X'Address.
5584 elsif Nkind
(N
) in N_Op_Compare
5585 and then Nkind
(Left_Opnd
(N
)) = N_Function_Call
5588 C
: constant Node_Id
:= Left_Opnd
(N
);
5589 F
: constant Node_Id
:= First
(Parameter_Associations
(C
));
5590 L
: constant Node_Id
:= Prefix
(F
);
5591 R
: constant Node_Id
:= Prefix
(Next
(F
));
5594 -- If an operand is an entity name, it is the formal of the
5595 -- predicate function, so replace it with the string value.
5596 -- It may be either operand in the call. The other operand
5597 -- is a static string from the original predicate.
5599 if Is_Entity_Name
(L
) then
5600 Rewrite
(Left_Opnd
(N
), New_Copy
(Val
));
5601 Rewrite
(Right_Opnd
(N
), New_Copy
(R
));
5604 Rewrite
(Left_Opnd
(N
), New_Copy
(L
));
5605 Rewrite
(Right_Opnd
(N
), New_Copy
(Val
));
5616 -- Start of processing for Real_Or_String_Static_Predicate_Matches
5619 -- First deal with special case of inherited predicate, where the
5620 -- predicate expression looks like:
5622 -- xxPredicate (typ (Ent)) and then Expr
5624 -- where Expr is the predicate expression for this level, and the
5625 -- left operand is the call to evaluate the inherited predicate.
5627 if Nkind
(Expr
) = N_And_Then
5628 and then Nkind
(Left_Opnd
(Expr
)) = N_Function_Call
5629 and then Is_Predicate_Function
(Entity
(Name
(Left_Opnd
(Expr
))))
5631 -- OK we have the inherited case, so make a call to evaluate the
5632 -- inherited predicate. If that fails, so do we!
5635 Real_Or_String_Static_Predicate_Matches
5637 Typ
=> Etype
(First_Formal
(Entity
(Name
(Left_Opnd
(Expr
))))))
5642 -- Use the right operand for the continued processing
5644 Copy
:= Copy_Separate_Tree
(Right_Opnd
(Expr
));
5646 -- Case where call to predicate function appears on its own (this means
5647 -- that the predicate at this level is just inherited from the parent).
5649 elsif Nkind
(Expr
) = N_Function_Call
then
5651 Typ
: constant Entity_Id
:=
5652 Etype
(First_Formal
(Entity
(Name
(Expr
))));
5655 -- If the inherited predicate is dynamic, just ignore it. We can't
5656 -- go trying to evaluate a dynamic predicate as a static one!
5658 if Has_Dynamic_Predicate_Aspect
(Typ
) then
5661 -- Otherwise inherited predicate is static, check for match
5664 return Real_Or_String_Static_Predicate_Matches
(Val
, Typ
);
5668 -- If not just an inherited predicate, copy whole expression
5671 Copy
:= Copy_Separate_Tree
(Expr
);
5674 -- Now we replace occurrences of the entity by the value
5678 -- And analyze the resulting static expression to see if it is True
5680 Analyze_And_Resolve
(Copy
, Standard_Boolean
);
5681 return Is_True
(Expr_Value
(Copy
));
5682 end Real_Or_String_Static_Predicate_Matches
;
5684 -------------------------
5685 -- Rewrite_In_Raise_CE --
5686 -------------------------
5688 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
) is
5689 Stat
: constant Boolean := Is_Static_Expression
(N
);
5690 Typ
: constant Entity_Id
:= Etype
(N
);
5693 -- If we want to raise CE in the condition of a N_Raise_CE node, we
5694 -- can just clear the condition if the reason is appropriate. We do
5695 -- not do this operation if the parent has a reason other than range
5696 -- check failed, because otherwise we would change the reason.
5698 if Present
(Parent
(N
))
5699 and then Nkind
(Parent
(N
)) = N_Raise_Constraint_Error
5700 and then Reason
(Parent
(N
)) =
5701 UI_From_Int
(RT_Exception_Code
'Pos (CE_Range_Check_Failed
))
5703 Set_Condition
(Parent
(N
), Empty
);
5705 -- Else build an explicit N_Raise_CE
5708 if Nkind
(Exp
) = N_Raise_Constraint_Error
then
5710 Make_Raise_Constraint_Error
(Sloc
(Exp
),
5711 Reason
=> Reason
(Exp
)));
5714 Make_Raise_Constraint_Error
(Sloc
(Exp
),
5715 Reason
=> CE_Range_Check_Failed
));
5718 Set_Raises_Constraint_Error
(N
);
5722 -- Set proper flags in result
5724 Set_Raises_Constraint_Error
(N
, True);
5725 Set_Is_Static_Expression
(N
, Stat
);
5726 end Rewrite_In_Raise_CE
;
5728 ---------------------
5729 -- String_Type_Len --
5730 ---------------------
5732 function String_Type_Len
(Stype
: Entity_Id
) return Uint
is
5733 NT
: constant Entity_Id
:= Etype
(First_Index
(Stype
));
5737 if Is_OK_Static_Subtype
(NT
) then
5740 T
:= Base_Type
(NT
);
5743 return Expr_Value
(Type_High_Bound
(T
)) -
5744 Expr_Value
(Type_Low_Bound
(T
)) + 1;
5745 end String_Type_Len
;
5747 ------------------------------------
5748 -- Subtypes_Statically_Compatible --
5749 ------------------------------------
5751 function Subtypes_Statically_Compatible
5754 Formal_Derived_Matching
: Boolean := False) return Boolean
5759 if Is_Scalar_Type
(T1
) then
5761 -- Definitely compatible if we match
5763 if Subtypes_Statically_Match
(T1
, T2
) then
5766 -- If either subtype is nonstatic then they're not compatible
5768 elsif not Is_OK_Static_Subtype
(T1
)
5770 not Is_OK_Static_Subtype
(T2
)
5774 -- Base types must match, but we don't check that (should we???) but
5775 -- we do at least check that both types are real, or both types are
5778 elsif Is_Real_Type
(T1
) /= Is_Real_Type
(T2
) then
5781 -- Here we check the bounds
5785 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
5786 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
5787 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
5788 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
5791 if Is_Real_Type
(T1
) then
5793 Expr_Value_R
(LB1
) > Expr_Value_R
(HB1
)
5795 (Expr_Value_R
(LB2
) <= Expr_Value_R
(LB1
)
5796 and then Expr_Value_R
(HB1
) <= Expr_Value_R
(HB2
));
5800 Expr_Value
(LB1
) > Expr_Value
(HB1
)
5802 (Expr_Value
(LB2
) <= Expr_Value
(LB1
)
5803 and then Expr_Value
(HB1
) <= Expr_Value
(HB2
));
5810 elsif Is_Access_Type
(T1
) then
5812 (not Is_Constrained
(T2
)
5813 or else Subtypes_Statically_Match
5814 (Designated_Type
(T1
), Designated_Type
(T2
)))
5815 and then not (Can_Never_Be_Null
(T2
)
5816 and then not Can_Never_Be_Null
(T1
));
5822 (Is_Composite_Type
(T1
) and then not Is_Constrained
(T2
))
5823 or else Subtypes_Statically_Match
5824 (T1
, T2
, Formal_Derived_Matching
);
5826 end Subtypes_Statically_Compatible
;
5828 -------------------------------
5829 -- Subtypes_Statically_Match --
5830 -------------------------------
5832 -- Subtypes statically match if they have statically matching constraints
5833 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
5834 -- they are the same identical constraint, or if they are static and the
5835 -- values match (RM 4.9.1(1)).
5837 -- In addition, in GNAT, the object size (Esize) values of the types must
5838 -- match if they are set (unless checking an actual for a formal derived
5839 -- type). The use of 'Object_Size can cause this to be false even if the
5840 -- types would otherwise match in the RM sense.
5842 function Subtypes_Statically_Match
5845 Formal_Derived_Matching
: Boolean := False) return Boolean
5848 -- A type always statically matches itself
5853 -- No match if sizes different (from use of 'Object_Size). This test
5854 -- is excluded if Formal_Derived_Matching is True, as the base types
5855 -- can be different in that case and typically have different sizes.
5856 -- ??? Frontend_Layout_On_Target used to set Esizes but this is no
5857 -- longer the case, consider removing the last test below.
5859 elsif not Formal_Derived_Matching
5860 and then Known_Static_Esize
(T1
)
5861 and then Known_Static_Esize
(T2
)
5862 and then Esize
(T1
) /= Esize
(T2
)
5866 -- No match if predicates do not match
5868 elsif not Predicates_Match
(T1
, T2
) then
5873 elsif Is_Scalar_Type
(T1
) then
5875 -- Base types must be the same
5877 if Base_Type
(T1
) /= Base_Type
(T2
) then
5881 -- A constrained numeric subtype never matches an unconstrained
5882 -- subtype, i.e. both types must be constrained or unconstrained.
5884 -- To understand the requirement for this test, see RM 4.9.1(1).
5885 -- As is made clear in RM 3.5.4(11), type Integer, for example is
5886 -- a constrained subtype with constraint bounds matching the bounds
5887 -- of its corresponding unconstrained base type. In this situation,
5888 -- Integer and Integer'Base do not statically match, even though
5889 -- they have the same bounds.
5891 -- We only apply this test to types in Standard and types that appear
5892 -- in user programs. That way, we do not have to be too careful about
5893 -- setting Is_Constrained right for Itypes.
5895 if Is_Numeric_Type
(T1
)
5896 and then (Is_Constrained
(T1
) /= Is_Constrained
(T2
))
5897 and then (Scope
(T1
) = Standard_Standard
5898 or else Comes_From_Source
(T1
))
5899 and then (Scope
(T2
) = Standard_Standard
5900 or else Comes_From_Source
(T2
))
5904 -- A generic scalar type does not statically match its base type
5905 -- (AI-311). In this case we make sure that the formals, which are
5906 -- first subtypes of their bases, are constrained.
5908 elsif Is_Generic_Type
(T1
)
5909 and then Is_Generic_Type
(T2
)
5910 and then (Is_Constrained
(T1
) /= Is_Constrained
(T2
))
5915 -- If there was an error in either range, then just assume the types
5916 -- statically match to avoid further junk errors.
5918 if No
(Scalar_Range
(T1
)) or else No
(Scalar_Range
(T2
))
5919 or else Error_Posted
(Scalar_Range
(T1
))
5920 or else Error_Posted
(Scalar_Range
(T2
))
5925 -- Otherwise both types have bounds that can be compared
5928 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
5929 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
5930 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
5931 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
5934 -- If the bounds are the same tree node, then match (common case)
5936 if LB1
= LB2
and then HB1
= HB2
then
5939 -- Otherwise bounds must be static and identical value
5942 if not Is_OK_Static_Subtype
(T1
)
5944 not Is_OK_Static_Subtype
(T2
)
5948 elsif Is_Real_Type
(T1
) then
5950 Expr_Value_R
(LB1
) = Expr_Value_R
(LB2
)
5952 Expr_Value_R
(HB1
) = Expr_Value_R
(HB2
);
5956 Expr_Value
(LB1
) = Expr_Value
(LB2
)
5958 Expr_Value
(HB1
) = Expr_Value
(HB2
);
5963 -- Type with discriminants
5965 elsif Has_Discriminants
(T1
) or else Has_Discriminants
(T2
) then
5967 -- Because of view exchanges in multiple instantiations, conformance
5968 -- checking might try to match a partial view of a type with no
5969 -- discriminants with a full view that has defaulted discriminants.
5970 -- In such a case, use the discriminant constraint of the full view,
5971 -- which must exist because we know that the two subtypes have the
5974 if Has_Discriminants
(T1
) /= Has_Discriminants
(T2
) then
5975 -- A generic actual type is declared through a subtype declaration
5976 -- and may have an inconsistent indication of the presence of
5977 -- discriminants, so check the type it renames.
5979 if Is_Generic_Actual_Type
(T1
)
5980 and then not Has_Discriminants
(Etype
(T1
))
5981 and then not Has_Discriminants
(T2
)
5985 elsif In_Instance
then
5986 if Is_Private_Type
(T2
)
5987 and then Present
(Full_View
(T2
))
5988 and then Has_Discriminants
(Full_View
(T2
))
5990 return Subtypes_Statically_Match
(T1
, Full_View
(T2
));
5992 elsif Is_Private_Type
(T1
)
5993 and then Present
(Full_View
(T1
))
5994 and then Has_Discriminants
(Full_View
(T1
))
5996 return Subtypes_Statically_Match
(Full_View
(T1
), T2
);
6007 DL1
: constant Elist_Id
:= Discriminant_Constraint
(T1
);
6008 DL2
: constant Elist_Id
:= Discriminant_Constraint
(T2
);
6016 elsif Is_Constrained
(T1
) /= Is_Constrained
(T2
) then
6020 -- Now loop through the discriminant constraints
6022 -- Note: the guard here seems necessary, since it is possible at
6023 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
6025 if Present
(DL1
) and then Present
(DL2
) then
6026 DA1
:= First_Elmt
(DL1
);
6027 DA2
:= First_Elmt
(DL2
);
6028 while Present
(DA1
) loop
6030 Expr1
: constant Node_Id
:= Node
(DA1
);
6031 Expr2
: constant Node_Id
:= Node
(DA2
);
6034 if not Is_OK_Static_Expression
(Expr1
)
6035 or else not Is_OK_Static_Expression
(Expr2
)
6039 -- If either expression raised a Constraint_Error,
6040 -- consider the expressions as matching, since this
6041 -- helps to prevent cascading errors.
6043 elsif Raises_Constraint_Error
(Expr1
)
6044 or else Raises_Constraint_Error
(Expr2
)
6048 elsif Expr_Value
(Expr1
) /= Expr_Value
(Expr2
) then
6061 -- A definite type does not match an indefinite or classwide type.
6062 -- However, a generic type with unknown discriminants may be
6063 -- instantiated with a type with no discriminants, and conformance
6064 -- checking on an inherited operation may compare the actual with the
6065 -- subtype that renames it in the instance.
6067 elsif Has_Unknown_Discriminants
(T1
) /= Has_Unknown_Discriminants
(T2
)
6070 Is_Generic_Actual_Type
(T1
) or else Is_Generic_Actual_Type
(T2
);
6074 elsif Is_Array_Type
(T1
) then
6076 -- If either subtype is unconstrained then both must be, and if both
6077 -- are unconstrained then no further checking is needed.
6079 if not Is_Constrained
(T1
) or else not Is_Constrained
(T2
) then
6080 return not (Is_Constrained
(T1
) or else Is_Constrained
(T2
));
6083 -- Both subtypes are constrained, so check that the index subtypes
6084 -- statically match.
6087 Index1
: Node_Id
:= First_Index
(T1
);
6088 Index2
: Node_Id
:= First_Index
(T2
);
6091 while Present
(Index1
) loop
6093 Subtypes_Statically_Match
(Etype
(Index1
), Etype
(Index2
))
6098 Next_Index
(Index1
);
6099 Next_Index
(Index2
);
6105 elsif Is_Access_Type
(T1
) then
6106 if Can_Never_Be_Null
(T1
) /= Can_Never_Be_Null
(T2
) then
6109 elsif Ekind_In
(T1
, E_Access_Subprogram_Type
,
6110 E_Anonymous_Access_Subprogram_Type
)
6114 (Designated_Type
(T1
),
6115 Designated_Type
(T2
));
6118 Subtypes_Statically_Match
6119 (Designated_Type
(T1
),
6120 Designated_Type
(T2
))
6121 and then Is_Access_Constant
(T1
) = Is_Access_Constant
(T2
);
6124 -- All other types definitely match
6129 end Subtypes_Statically_Match
;
6135 function Test
(Cond
: Boolean) return Uint
is
6144 ---------------------
6145 -- Test_Comparison --
6146 ---------------------
6148 procedure Test_Comparison
6150 Assume_Valid
: Boolean;
6151 True_Result
: out Boolean;
6152 False_Result
: out Boolean)
6154 Left
: constant Node_Id
:= Left_Opnd
(Op
);
6155 Left_Typ
: constant Entity_Id
:= Etype
(Left
);
6156 Orig_Op
: constant Node_Id
:= Original_Node
(Op
);
6158 procedure Replacement_Warning
(Msg
: String);
6159 -- Emit a warning on a comparison that can be replaced by '='
6161 -------------------------
6162 -- Replacement_Warning --
6163 -------------------------
6165 procedure Replacement_Warning
(Msg
: String) is
6167 if Constant_Condition_Warnings
6168 and then Comes_From_Source
(Orig_Op
)
6169 and then Is_Integer_Type
(Left_Typ
)
6170 and then not Error_Posted
(Op
)
6171 and then not Has_Warnings_Off
(Left_Typ
)
6172 and then not In_Instance
6174 Error_Msg_N
(Msg
, Op
);
6176 end Replacement_Warning
;
6180 Res
: constant Compare_Result
:=
6181 Compile_Time_Compare
(Left
, Right_Opnd
(Op
), Assume_Valid
);
6183 -- Start of processing for Test_Comparison
6186 case N_Op_Compare
(Nkind
(Op
)) is
6188 True_Result
:= Res
= EQ
;
6189 False_Result
:= Res
= LT
or else Res
= GT
or else Res
= NE
;
6192 True_Result
:= Res
in Compare_GE
;
6193 False_Result
:= Res
= LT
;
6195 if Res
= LE
and then Nkind
(Orig_Op
) = N_Op_Ge
then
6197 ("can never be greater than, could replace by ""'=""?c?");
6201 True_Result
:= Res
= GT
;
6202 False_Result
:= Res
in Compare_LE
;
6205 True_Result
:= Res
in Compare_LE
;
6206 False_Result
:= Res
= GT
;
6208 if Res
= GE
and then Nkind
(Orig_Op
) = N_Op_Le
then
6210 ("can never be less than, could replace by ""'=""?c?");
6214 True_Result
:= Res
= LT
;
6215 False_Result
:= Res
in Compare_GE
;
6218 True_Result
:= Res
= NE
or else Res
= GT
or else Res
= LT
;
6219 False_Result
:= Res
= EQ
;
6221 end Test_Comparison
;
6223 ---------------------------------
6224 -- Test_Expression_Is_Foldable --
6225 ---------------------------------
6229 procedure Test_Expression_Is_Foldable
6239 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
6243 -- If operand is Any_Type, just propagate to result and do not
6244 -- try to fold, this prevents cascaded errors.
6246 if Etype
(Op1
) = Any_Type
then
6247 Set_Etype
(N
, Any_Type
);
6250 -- If operand raises Constraint_Error, then replace node N with the
6251 -- raise Constraint_Error node, and we are obviously not foldable.
6252 -- Note that this replacement inherits the Is_Static_Expression flag
6253 -- from the operand.
6255 elsif Raises_Constraint_Error
(Op1
) then
6256 Rewrite_In_Raise_CE
(N
, Op1
);
6259 -- If the operand is not static, then the result is not static, and
6260 -- all we have to do is to check the operand since it is now known
6261 -- to appear in a non-static context.
6263 elsif not Is_Static_Expression
(Op1
) then
6264 Check_Non_Static_Context
(Op1
);
6265 Fold
:= Compile_Time_Known_Value
(Op1
);
6268 -- An expression of a formal modular type is not foldable because
6269 -- the modulus is unknown.
6271 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
6272 and then Is_Generic_Type
(Etype
(Op1
))
6274 Check_Non_Static_Context
(Op1
);
6277 -- Here we have the case of an operand whose type is OK, which is
6278 -- static, and which does not raise Constraint_Error, we can fold.
6281 Set_Is_Static_Expression
(N
);
6285 end Test_Expression_Is_Foldable
;
6289 procedure Test_Expression_Is_Foldable
6295 CRT_Safe
: Boolean := False)
6297 Rstat
: constant Boolean := Is_Static_Expression
(Op1
)
6299 Is_Static_Expression
(Op2
);
6305 -- Inhibit folding if -gnatd.f flag set
6307 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
6311 -- If either operand is Any_Type, just propagate to result and
6312 -- do not try to fold, this prevents cascaded errors.
6314 if Etype
(Op1
) = Any_Type
or else Etype
(Op2
) = Any_Type
then
6315 Set_Etype
(N
, Any_Type
);
6318 -- If left operand raises Constraint_Error, then replace node N with the
6319 -- Raise_Constraint_Error node, and we are obviously not foldable.
6320 -- Is_Static_Expression is set from the two operands in the normal way,
6321 -- and we check the right operand if it is in a non-static context.
6323 elsif Raises_Constraint_Error
(Op1
) then
6325 Check_Non_Static_Context
(Op2
);
6328 Rewrite_In_Raise_CE
(N
, Op1
);
6329 Set_Is_Static_Expression
(N
, Rstat
);
6332 -- Similar processing for the case of the right operand. Note that we
6333 -- don't use this routine for the short-circuit case, so we do not have
6334 -- to worry about that special case here.
6336 elsif Raises_Constraint_Error
(Op2
) then
6338 Check_Non_Static_Context
(Op1
);
6341 Rewrite_In_Raise_CE
(N
, Op2
);
6342 Set_Is_Static_Expression
(N
, Rstat
);
6345 -- Exclude expressions of a generic modular type, as above
6347 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
6348 and then Is_Generic_Type
(Etype
(Op1
))
6350 Check_Non_Static_Context
(Op1
);
6353 -- If result is not static, then check non-static contexts on operands
6354 -- since one of them may be static and the other one may not be static.
6356 elsif not Rstat
then
6357 Check_Non_Static_Context
(Op1
);
6358 Check_Non_Static_Context
(Op2
);
6361 Fold
:= CRT_Safe_Compile_Time_Known_Value
(Op1
)
6362 and then CRT_Safe_Compile_Time_Known_Value
(Op2
);
6364 Fold
:= Compile_Time_Known_Value
(Op1
)
6365 and then Compile_Time_Known_Value
(Op2
);
6370 -- Else result is static and foldable. Both operands are static, and
6371 -- neither raises Constraint_Error, so we can definitely fold.
6374 Set_Is_Static_Expression
(N
);
6379 end Test_Expression_Is_Foldable
;
6385 function Test_In_Range
6388 Assume_Valid
: Boolean;
6389 Fixed_Int
: Boolean;
6390 Int_Real
: Boolean) return Range_Membership
6395 pragma Warnings
(Off
, Assume_Valid
);
6396 -- For now Assume_Valid is unreferenced since the current implementation
6397 -- always returns Unknown if N is not a compile-time-known value, but we
6398 -- keep the parameter to allow for future enhancements in which we try
6399 -- to get the information in the variable case as well.
6402 -- If an error was posted on expression, then return Unknown, we do not
6403 -- want cascaded errors based on some false analysis of a junk node.
6405 if Error_Posted
(N
) then
6408 -- Expression that raises Constraint_Error is an odd case. We certainly
6409 -- do not want to consider it to be in range. It might make sense to
6410 -- consider it always out of range, but this causes incorrect error
6411 -- messages about static expressions out of range. So we just return
6412 -- Unknown, which is always safe.
6414 elsif Raises_Constraint_Error
(N
) then
6417 -- Universal types have no range limits, so always in range
6419 elsif Typ
= Universal_Integer
or else Typ
= Universal_Real
then
6422 -- Never known if not scalar type. Don't know if this can actually
6423 -- happen, but our spec allows it, so we must check.
6425 elsif not Is_Scalar_Type
(Typ
) then
6428 -- Never known if this is a generic type, since the bounds of generic
6429 -- types are junk. Note that if we only checked for static expressions
6430 -- (instead of compile-time-known values) below, we would not need this
6431 -- check, because values of a generic type can never be static, but they
6432 -- can be known at compile time.
6434 elsif Is_Generic_Type
(Typ
) then
6437 -- Case of a known compile time value, where we can check if it is in
6438 -- the bounds of the given type.
6440 elsif Compile_Time_Known_Value
(N
) then
6449 Lo
:= Type_Low_Bound
(Typ
);
6450 Hi
:= Type_High_Bound
(Typ
);
6452 LB_Known
:= Compile_Time_Known_Value
(Lo
);
6453 HB_Known
:= Compile_Time_Known_Value
(Hi
);
6455 -- Fixed point types should be considered as such only if flag
6456 -- Fixed_Int is set to False.
6458 if Is_Floating_Point_Type
(Typ
)
6459 or else (Is_Fixed_Point_Type
(Typ
) and then not Fixed_Int
)
6462 Valr
:= Expr_Value_R
(N
);
6464 if LB_Known
and HB_Known
then
6465 if Valr
>= Expr_Value_R
(Lo
)
6467 Valr
<= Expr_Value_R
(Hi
)
6471 return Out_Of_Range
;
6474 elsif (LB_Known
and then Valr
< Expr_Value_R
(Lo
))
6476 (HB_Known
and then Valr
> Expr_Value_R
(Hi
))
6478 return Out_Of_Range
;
6485 Val
:= Expr_Value
(N
);
6487 if LB_Known
and HB_Known
then
6488 if Val
>= Expr_Value
(Lo
) and then Val
<= Expr_Value
(Hi
)
6492 return Out_Of_Range
;
6495 elsif (LB_Known
and then Val
< Expr_Value
(Lo
))
6497 (HB_Known
and then Val
> Expr_Value
(Hi
))
6499 return Out_Of_Range
;
6507 -- Here for value not known at compile time. Case of expression subtype
6508 -- is Typ or is a subtype of Typ, and we can assume expression is valid.
6509 -- In this case we know it is in range without knowing its value.
6512 and then (Etype
(N
) = Typ
or else Is_Subtype_Of
(Etype
(N
), Typ
))
6516 -- Another special case. For signed integer types, if the target type
6517 -- has Is_Known_Valid set, and the source type does not have a larger
6518 -- size, then the source value must be in range. We exclude biased
6519 -- types, because they bizarrely can generate out of range values.
6521 elsif Is_Signed_Integer_Type
(Etype
(N
))
6522 and then Is_Known_Valid
(Typ
)
6523 and then Esize
(Etype
(N
)) <= Esize
(Typ
)
6524 and then not Has_Biased_Representation
(Etype
(N
))
6528 -- For all other cases, result is unknown
6539 procedure To_Bits
(U
: Uint
; B
: out Bits
) is
6541 for J
in 0 .. B
'Last loop
6542 B
(J
) := (U
/ (2 ** J
)) mod 2 /= 0;
6546 --------------------
6547 -- Why_Not_Static --
6548 --------------------
6550 procedure Why_Not_Static
(Expr
: Node_Id
) is
6551 N
: constant Node_Id
:= Original_Node
(Expr
);
6552 Typ
: Entity_Id
:= Empty
;
6557 procedure Why_Not_Static_List
(L
: List_Id
);
6558 -- A version that can be called on a list of expressions. Finds all
6559 -- non-static violations in any element of the list.
6561 -------------------------
6562 -- Why_Not_Static_List --
6563 -------------------------
6565 procedure Why_Not_Static_List
(L
: List_Id
) is
6568 if Is_Non_Empty_List
(L
) then
6570 while Present
(N
) loop
6575 end Why_Not_Static_List
;
6577 -- Start of processing for Why_Not_Static
6580 -- Ignore call on error or empty node
6582 if No
(Expr
) or else Nkind
(Expr
) = N_Error
then
6586 -- Preprocessing for sub expressions
6588 if Nkind
(Expr
) in N_Subexpr
then
6590 -- Nothing to do if expression is static
6592 if Is_OK_Static_Expression
(Expr
) then
6596 -- Test for Constraint_Error raised
6598 if Raises_Constraint_Error
(Expr
) then
6600 -- Special case membership to find out which piece to flag
6602 if Nkind
(N
) in N_Membership_Test
then
6603 if Raises_Constraint_Error
(Left_Opnd
(N
)) then
6604 Why_Not_Static
(Left_Opnd
(N
));
6607 elsif Present
(Right_Opnd
(N
))
6608 and then Raises_Constraint_Error
(Right_Opnd
(N
))
6610 Why_Not_Static
(Right_Opnd
(N
));
6614 pragma Assert
(Present
(Alternatives
(N
)));
6616 Alt
:= First
(Alternatives
(N
));
6617 while Present
(Alt
) loop
6618 if Raises_Constraint_Error
(Alt
) then
6619 Why_Not_Static
(Alt
);
6627 -- Special case a range to find out which bound to flag
6629 elsif Nkind
(N
) = N_Range
then
6630 if Raises_Constraint_Error
(Low_Bound
(N
)) then
6631 Why_Not_Static
(Low_Bound
(N
));
6634 elsif Raises_Constraint_Error
(High_Bound
(N
)) then
6635 Why_Not_Static
(High_Bound
(N
));
6639 -- Special case attribute to see which part to flag
6641 elsif Nkind
(N
) = N_Attribute_Reference
then
6642 if Raises_Constraint_Error
(Prefix
(N
)) then
6643 Why_Not_Static
(Prefix
(N
));
6647 if Present
(Expressions
(N
)) then
6648 Exp
:= First
(Expressions
(N
));
6649 while Present
(Exp
) loop
6650 if Raises_Constraint_Error
(Exp
) then
6651 Why_Not_Static
(Exp
);
6659 -- Special case a subtype name
6661 elsif Is_Entity_Name
(Expr
) and then Is_Type
(Entity
(Expr
)) then
6663 ("!& is not a static subtype (RM 4.9(26))", N
, Entity
(Expr
));
6667 -- End of special cases
6670 ("!expression raises exception, cannot be static (RM 4.9(34))",
6675 -- If no type, then something is pretty wrong, so ignore
6677 Typ
:= Etype
(Expr
);
6683 -- Type must be scalar or string type (but allow Bignum, since this
6684 -- is really a scalar type from our point of view in this diagnosis).
6686 if not Is_Scalar_Type
(Typ
)
6687 and then not Is_String_Type
(Typ
)
6688 and then not Is_RTE
(Typ
, RE_Bignum
)
6691 ("!static expression must have scalar or string type " &
6697 -- If we got through those checks, test particular node kind
6703 when N_Expanded_Name
6709 if Is_Named_Number
(E
) then
6712 elsif Ekind
(E
) = E_Constant
then
6714 -- One case we can give a metter message is when we have a
6715 -- string literal created by concatenating an aggregate with
6716 -- an others expression.
6718 Entity_Case
: declare
6719 CV
: constant Node_Id
:= Constant_Value
(E
);
6720 CO
: constant Node_Id
:= Original_Node
(CV
);
6722 function Is_Aggregate
(N
: Node_Id
) return Boolean;
6723 -- See if node N came from an others aggregate, if so
6724 -- return True and set Error_Msg_Sloc to aggregate.
6730 function Is_Aggregate
(N
: Node_Id
) return Boolean is
6732 if Nkind
(Original_Node
(N
)) = N_Aggregate
then
6733 Error_Msg_Sloc
:= Sloc
(Original_Node
(N
));
6736 elsif Is_Entity_Name
(N
)
6737 and then Ekind
(Entity
(N
)) = E_Constant
6739 Nkind
(Original_Node
(Constant_Value
(Entity
(N
)))) =
6743 Sloc
(Original_Node
(Constant_Value
(Entity
(N
))));
6751 -- Start of processing for Entity_Case
6754 if Is_Aggregate
(CV
)
6755 or else (Nkind
(CO
) = N_Op_Concat
6756 and then (Is_Aggregate
(Left_Opnd
(CO
))
6758 Is_Aggregate
(Right_Opnd
(CO
))))
6760 Error_Msg_N
("!aggregate (#) is never static", N
);
6762 elsif No
(CV
) or else not Is_Static_Expression
(CV
) then
6764 ("!& is not a static constant (RM 4.9(5))", N
, E
);
6768 elsif Is_Type
(E
) then
6770 ("!& is not a static subtype (RM 4.9(26))", N
, E
);
6774 ("!& is not static constant or named number "
6775 & "(RM 4.9(5))", N
, E
);
6784 if Nkind
(N
) in N_Op_Shift
then
6786 ("!shift functions are never static (RM 4.9(6,18))", N
);
6788 Why_Not_Static
(Left_Opnd
(N
));
6789 Why_Not_Static
(Right_Opnd
(N
));
6795 Why_Not_Static
(Right_Opnd
(N
));
6797 -- Attribute reference
6799 when N_Attribute_Reference
=>
6800 Why_Not_Static_List
(Expressions
(N
));
6802 E
:= Etype
(Prefix
(N
));
6804 if E
= Standard_Void_Type
then
6808 -- Special case non-scalar'Size since this is a common error
6810 if Attribute_Name
(N
) = Name_Size
then
6812 ("!size attribute is only static for static scalar type "
6813 & "(RM 4.9(7,8))", N
);
6817 elsif Is_Array_Type
(E
) then
6818 if not Nam_In
(Attribute_Name
(N
), Name_First
,
6823 ("!static array attribute must be Length, First, or Last "
6824 & "(RM 4.9(8))", N
);
6826 -- Since we know the expression is not-static (we already
6827 -- tested for this, must mean array is not static).
6831 ("!prefix is non-static array (RM 4.9(8))", Prefix
(N
));
6836 -- Special case generic types, since again this is a common source
6839 elsif Is_Generic_Actual_Type
(E
) or else Is_Generic_Type
(E
) then
6841 ("!attribute of generic type is never static "
6842 & "(RM 4.9(7,8))", N
);
6844 elsif Is_OK_Static_Subtype
(E
) then
6847 elsif Is_Scalar_Type
(E
) then
6849 ("!prefix type for attribute is not static scalar subtype "
6850 & "(RM 4.9(7))", N
);
6854 ("!static attribute must apply to array/scalar type "
6855 & "(RM 4.9(7,8))", N
);
6860 when N_String_Literal
=>
6862 ("!subtype of string literal is non-static (RM 4.9(4))", N
);
6864 -- Explicit dereference
6866 when N_Explicit_Dereference
=>
6868 ("!explicit dereference is never static (RM 4.9)", N
);
6872 when N_Function_Call
=>
6873 Why_Not_Static_List
(Parameter_Associations
(N
));
6875 -- Complain about non-static function call unless we have Bignum
6876 -- which means that the underlying expression is really some
6877 -- scalar arithmetic operation.
6879 if not Is_RTE
(Typ
, RE_Bignum
) then
6880 Error_Msg_N
("!non-static function call (RM 4.9(6,18))", N
);
6883 -- Parameter assocation (test actual parameter)
6885 when N_Parameter_Association
=>
6886 Why_Not_Static
(Explicit_Actual_Parameter
(N
));
6888 -- Indexed component
6890 when N_Indexed_Component
=>
6891 Error_Msg_N
("!indexed component is never static (RM 4.9)", N
);
6895 when N_Procedure_Call_Statement
=>
6896 Error_Msg_N
("!procedure call is never static (RM 4.9)", N
);
6898 -- Qualified expression (test expression)
6900 when N_Qualified_Expression
=>
6901 Why_Not_Static
(Expression
(N
));
6906 | N_Extension_Aggregate
6908 Error_Msg_N
("!an aggregate is never static (RM 4.9)", N
);
6913 Why_Not_Static
(Low_Bound
(N
));
6914 Why_Not_Static
(High_Bound
(N
));
6916 -- Range constraint, test range expression
6918 when N_Range_Constraint
=>
6919 Why_Not_Static
(Range_Expression
(N
));
6921 -- Subtype indication, test constraint
6923 when N_Subtype_Indication
=>
6924 Why_Not_Static
(Constraint
(N
));
6926 -- Selected component
6928 when N_Selected_Component
=>
6929 Error_Msg_N
("!selected component is never static (RM 4.9)", N
);
6934 Error_Msg_N
("!slice is never static (RM 4.9)", N
);
6936 when N_Type_Conversion
=>
6937 Why_Not_Static
(Expression
(N
));
6939 if not Is_Scalar_Type
(Entity
(Subtype_Mark
(N
)))
6940 or else not Is_OK_Static_Subtype
(Entity
(Subtype_Mark
(N
)))
6943 ("!static conversion requires static scalar subtype result "
6944 & "(RM 4.9(9))", N
);
6947 -- Unchecked type conversion
6949 when N_Unchecked_Type_Conversion
=>
6951 ("!unchecked type conversion is never static (RM 4.9)", N
);
6953 -- All other cases, no reason to give