1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2019, 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).
4614 -- We mark the node as analyzed so that its type is not erased by
4615 -- calling Analyze_Real_Literal.
4618 Set_Is_Static_Expression (N, Static);
4622 Set_Is_Static_Expression (N, Static);
4629 function From_Bits (B : Bits; T : Entity_Id) return Uint is
4633 for J in 0 .. B'Last loop
4639 if Non_Binary_Modulus (T) then
4640 V := V mod Modulus (T);
4646 --------------------
4647 -- Get_String_Val --
4648 --------------------
4650 function Get_String_Val (N : Node_Id) return Node_Id is
4652 if Nkind_In (N, N_String_Literal, N_Character_Literal) then
4655 pragma Assert (Is_Entity_Name (N));
4656 return Get_String_Val (Constant_Value (Entity (N)));
4664 procedure Initialize is
4666 CV_Cache := (others => (Node_High_Bound, Uint_0));
4669 --------------------
4670 -- In_Subrange_Of --
4671 --------------------
4673 function In_Subrange_Of
4676 Fixed_Int : Boolean := False) return Boolean
4685 if T1 = T2 or else Is_Subtype_Of (T1, T2) then
4688 -- Never in range if both types are not scalar. Don't know if this can
4689 -- actually happen, but just in case.
4691 elsif not Is_Scalar_Type (T1) or else not Is_Scalar_Type (T2) then
4694 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
4695 -- definitely not compatible with T2.
4697 elsif Is_Floating_Point_Type (T1)
4698 and then Has_Infinities (T1)
4699 and then Is_Floating_Point_Type (T2)
4700 and then not Has_Infinities (T2)
4705 L1 := Type_Low_Bound (T1);
4706 H1 := Type_High_Bound (T1);
4708 L2 := Type_Low_Bound (T2);
4709 H2 := Type_High_Bound (T2);
4711 -- Check bounds to see if comparison possible at compile time
4713 if Compile_Time_Compare (L1, L2, Assume_Valid => True) in Compare_GE
4715 Compile_Time_Compare (H1, H2, Assume_Valid => True) in Compare_LE
4720 -- If bounds not comparable at compile time, then the bounds of T2
4721 -- must be compile-time-known or we cannot answer the query.
4723 if not Compile_Time_Known_Value (L2)
4724 or else not Compile_Time_Known_Value (H2)
4729 -- If the bounds of T1 are know at compile time then use these
4730 -- ones, otherwise use the bounds of the base type (which are of
4731 -- course always static).
4733 if not Compile_Time_Known_Value (L1) then
4734 L1 := Type_Low_Bound (Base_Type (T1));
4737 if not Compile_Time_Known_Value (H1) then
4738 H1 := Type_High_Bound (Base_Type (T1));
4741 -- Fixed point types should be considered as such only if
4742 -- flag Fixed_Int is set to False.
4744 if Is_Floating_Point_Type (T1) or else Is_Floating_Point_Type (T2)
4745 or else (Is_Fixed_Point_Type (T1) and then not Fixed_Int)
4746 or else (Is_Fixed_Point_Type (T2) and then not Fixed_Int)
4749 Expr_Value_R (L2) <= Expr_Value_R (L1)
4751 Expr_Value_R (H2) >= Expr_Value_R (H1);
4755 Expr_Value (L2) <= Expr_Value (L1)
4757 Expr_Value (H2) >= Expr_Value (H1);
4762 -- If any exception occurs, it means that we have some bug in the compiler
4763 -- possibly triggered by a previous error, or by some unforeseen peculiar
4764 -- occurrence. However, this is only an optimization attempt, so there is
4765 -- really no point in crashing the compiler. Instead we just decide, too
4766 -- bad, we can't figure out the answer in this case after all.
4771 -- Debug flag K disables this behavior (useful for debugging)
4773 if Debug_Flag_K then
4784 function Is_In_Range
4787 Assume_Valid : Boolean := False;
4788 Fixed_Int : Boolean := False;
4789 Int_Real : Boolean := False) return Boolean
4793 Test_In_Range (N, Typ, Assume_Valid, Fixed_Int, Int_Real) = In_Range;
4800 function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
4802 if Compile_Time_Known_Value (Lo)
4803 and then Compile_Time_Known_Value (Hi)
4806 Typ : Entity_Id := Etype (Lo);
4808 -- When called from the frontend, as part of the analysis of
4809 -- potentially static expressions, Typ will be the full view of a
4810 -- type with all the info needed to answer this query. When called
4811 -- from the backend, for example to know whether a range of a loop
4812 -- is null, Typ might be a private type and we need to explicitly
4813 -- switch to its corresponding full view to access the same info.
4815 if Is_Incomplete_Or_Private_Type (Typ)
4816 and then Present (Full_View (Typ))
4818 Typ := Full_View (Typ);
4821 if Is_Discrete_Type (Typ) then
4822 return Expr_Value (Lo) > Expr_Value (Hi);
4823 else pragma Assert (Is_Real_Type (Typ));
4824 return Expr_Value_R (Lo) > Expr_Value_R (Hi);
4832 -------------------------
4833 -- Is_OK_Static_Choice --
4834 -------------------------
4836 function Is_OK_Static_Choice (Choice : Node_Id) return Boolean is
4838 -- Check various possibilities for choice
4840 -- Note: for membership tests, we test more cases than are possible
4841 -- (in particular subtype indication), but it doesn't matter because
4842 -- it just won't occur (we have already done a syntax check).
4844 if Nkind (Choice) = N_Others_Choice then
4847 elsif Nkind (Choice) = N_Range then
4848 return Is_OK_Static_Range (Choice);
4850 elsif Nkind (Choice) = N_Subtype_Indication
4851 or else (Is_Entity_Name (Choice) and then Is_Type (Entity (Choice)))
4853 return Is_OK_Static_Subtype (Etype (Choice));
4856 return Is_OK_Static_Expression (Choice);
4858 end Is_OK_Static_Choice;
4860 ------------------------------
4861 -- Is_OK_Static_Choice_List --
4862 ------------------------------
4864 function Is_OK_Static_Choice_List (Choices : List_Id) return Boolean is
4868 if not Is_Static_Choice_List (Choices) then
4872 Choice := First (Choices);
4873 while Present (Choice) loop
4874 if not Is_OK_Static_Choice (Choice) then
4875 Set_Raises_Constraint_Error (Choice);
4883 end Is_OK_Static_Choice_List;
4885 -----------------------------
4886 -- Is_OK_Static_Expression --
4887 -----------------------------
4889 function Is_OK_Static_Expression (N : Node_Id) return Boolean is
4891 return Is_Static_Expression (N) and then not Raises_Constraint_Error (N);
4892 end Is_OK_Static_Expression;
4894 ------------------------
4895 -- Is_OK_Static_Range --
4896 ------------------------
4898 -- A static range is a range whose bounds are static expressions, or a
4899 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4900 -- We have already converted range attribute references, so we get the
4901 -- "or" part of this rule without needing a special test.
4903 function Is_OK_Static_Range (N : Node_Id) return Boolean is
4905 return Is_OK_Static_Expression (Low_Bound (N))
4906 and then Is_OK_Static_Expression (High_Bound (N));
4907 end Is_OK_Static_Range;
4909 --------------------------
4910 -- Is_OK_Static_Subtype --
4911 --------------------------
4913 -- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
4914 -- neither bound raises Constraint_Error when evaluated.
4916 function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean is
4917 Base_T : constant Entity_Id := Base_Type (Typ);
4918 Anc_Subt : Entity_Id;
4921 -- First a quick check on the non static subtype flag. As described
4922 -- in further detail in Einfo, this flag is not decisive in all cases,
4923 -- but if it is set, then the subtype is definitely non-static.
4925 if Is_Non_Static_Subtype (Typ) then
4929 Anc_Subt := Ancestor_Subtype (Typ);
4931 if Anc_Subt = Empty then
4935 if Is_Generic_Type (Root_Type (Base_T))
4936 or else Is_Generic_Actual_Type (Base_T)
4940 elsif Has_Dynamic_Predicate_Aspect (Typ) then
4945 elsif Is_String_Type (Typ) then
4947 Ekind (Typ) = E_String_Literal_Subtype
4949 (Is_OK_Static_Subtype (Component_Type (Typ))
4950 and then Is_OK_Static_Subtype (Etype (First_Index (Typ))));
4954 elsif Is_Scalar_Type (Typ) then
4955 if Base_T = Typ then
4959 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
4960 -- Get_Type_{Low,High}_Bound.
4962 return Is_OK_Static_Subtype (Anc_Subt)
4963 and then Is_OK_Static_Expression (Type_Low_Bound (Typ))
4964 and then Is_OK_Static_Expression (Type_High_Bound (Typ));
4967 -- Types other than string and scalar types are never static
4972 end Is_OK_Static_Subtype;
4974 ---------------------
4975 -- Is_Out_Of_Range --
4976 ---------------------
4978 function Is_Out_Of_Range
4981 Assume_Valid : Boolean := False;
4982 Fixed_Int : Boolean := False;
4983 Int_Real : Boolean := False) return Boolean
4986 return Test_In_Range (N, Typ, Assume_Valid, Fixed_Int, Int_Real) =
4988 end Is_Out_Of_Range;
4990 ----------------------
4991 -- Is_Static_Choice --
4992 ----------------------
4994 function Is_Static_Choice (Choice : Node_Id) return Boolean is
4996 -- Check various possibilities for choice
4998 -- Note: for membership tests, we test more cases than are possible
4999 -- (in particular subtype indication), but it doesn't matter because
5000 -- it just won't occur (we have already done a syntax check).
5002 if Nkind (Choice) = N_Others_Choice then
5005 elsif Nkind (Choice) = N_Range then
5006 return Is_Static_Range (Choice);
5008 elsif Nkind (Choice) = N_Subtype_Indication
5009 or else (Is_Entity_Name (Choice) and then Is_Type (Entity (Choice)))
5011 return Is_Static_Subtype (Etype (Choice));
5014 return Is_Static_Expression (Choice);
5016 end Is_Static_Choice;
5018 ---------------------------
5019 -- Is_Static_Choice_List --
5020 ---------------------------
5022 function Is_Static_Choice_List (Choices : List_Id) return Boolean is
5026 Choice := First (Choices);
5027 while Present (Choice) loop
5028 if not Is_Static_Choice (Choice) then
5036 end Is_Static_Choice_List;
5038 ---------------------
5039 -- Is_Static_Range --
5040 ---------------------
5042 -- A static range is a range whose bounds are static expressions, or a
5043 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
5044 -- We have already converted range attribute references, so we get the
5045 -- "or" part of this rule without needing a special test.
5047 function Is_Static_Range (N : Node_Id) return Boolean is
5049 return Is_Static_Expression (Low_Bound (N))
5051 Is_Static_Expression (High_Bound (N));
5052 end Is_Static_Range;
5054 -----------------------
5055 -- Is_Static_Subtype --
5056 -----------------------
5058 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
5060 function Is_Static_Subtype (Typ : Entity_Id) return Boolean is
5061 Base_T : constant Entity_Id := Base_Type (Typ);
5062 Anc_Subt : Entity_Id;
5065 -- First a quick check on the non static subtype flag. As described
5066 -- in further detail in Einfo, this flag is not decisive in all cases,
5067 -- but if it is set, then the subtype is definitely non-static.
5069 if Is_Non_Static_Subtype (Typ) then
5073 Anc_Subt := Ancestor_Subtype (Typ);
5075 if Anc_Subt = Empty then
5079 if Is_Generic_Type (Root_Type (Base_T))
5080 or else Is_Generic_Actual_Type (Base_T)
5084 -- If there is a dynamic predicate for the type (declared or inherited)
5085 -- the expression is not static.
5087 elsif Has_Dynamic_Predicate_Aspect (Typ)
5088 or else (Is_Derived_Type (Typ)
5089 and then Has_Aspect (Typ, Aspect_Dynamic_Predicate))
5095 elsif Is_String_Type (Typ) then
5097 Ekind (Typ) = E_String_Literal_Subtype
5098 or else (Is_Static_Subtype (Component_Type (Typ))
5099 and then Is_Static_Subtype (Etype (First_Index (Typ))));
5103 elsif Is_Scalar_Type (Typ) then
5104 if Base_T = Typ then
5108 return Is_Static_Subtype (Anc_Subt)
5109 and then Is_Static_Expression (Type_Low_Bound (Typ))
5110 and then Is_Static_Expression (Type_High_Bound (Typ));
5113 -- Types other than string and scalar types are never static
5118 end Is_Static_Subtype;
5120 -------------------------------
5121 -- Is_Statically_Unevaluated --
5122 -------------------------------
5124 function Is_Statically_Unevaluated (Expr : Node_Id) return Boolean is
5125 function Check_Case_Expr_Alternative
5126 (CEA : Node_Id) return Match_Result;
5127 -- We have a message emanating from the Expression of a case expression
5128 -- alternative. We examine this alternative, as follows:
5130 -- If the selecting expression of the parent case is non-static, or
5131 -- if any of the discrete choices of the given case alternative are
5132 -- non-static or raise Constraint_Error, return Non_Static.
5134 -- Otherwise check if the selecting expression matches any of the given
5135 -- discrete choices. If so, the alternative is executed and we return
5136 -- Match, otherwise, the alternative can never be executed, and so we
5139 ---------------------------------
5140 -- Check_Case_Expr_Alternative --
5141 ---------------------------------
5143 function Check_Case_Expr_Alternative
5144 (CEA : Node_Id) return Match_Result
5146 Case_Exp : constant Node_Id := Parent (CEA);
5151 pragma Assert (Nkind (Case_Exp) = N_Case_Expression);
5153 -- Check that selecting expression is static
5155 if not Is_OK_Static_Expression (Expression (Case_Exp)) then
5159 if not Is_OK_Static_Choice_List (Discrete_Choices (CEA)) then
5163 -- All choices are now known to be static. Now see if alternative
5164 -- matches one of the choices.
5166 Choice := First (Discrete_Choices (CEA));
5167 while Present (Choice) loop
5169 -- Check various possibilities for choice, returning Match if we
5170 -- find the selecting value matches any of the choices. Note that
5171 -- we know we are the last choice, so we don't have to keep going.
5173 if Nkind (Choice) = N_Others_Choice then
5175 -- Others choice is a bit annoying, it matches if none of the
5176 -- previous alternatives matches (note that we know we are the
5177 -- last alternative in this case, so we can just go backwards
5178 -- from us to see if any previous one matches).
5180 Prev_CEA := Prev (CEA);
5181 while Present (Prev_CEA) loop
5182 if Check_Case_Expr_Alternative (Prev_CEA) = Match then
5191 -- Else we have a normal static choice
5193 elsif Choice_Matches (Expression (Case_Exp), Choice) = Match then
5197 -- If we fall through, it means that the discrete choice did not
5198 -- match the selecting expression, so continue.
5203 -- If we get through that loop then all choices were static, and none
5204 -- of them matched the selecting expression. So return No_Match.
5207 end Check_Case_Expr_Alternative;
5215 -- Start of processing for Is_Statically_Unevaluated
5218 -- The (32.x) references here are from RM section 4.9
5220 -- (32.1) An expression is statically unevaluated if it is part of ...
5222 -- This means we have to climb the tree looking for one of the cases
5229 -- (32.2) The right operand of a static short-circuit control form
5230 -- whose value is determined by its left operand.
5232 -- AND THEN with False as left operand
5234 if Nkind (P) = N_And_Then
5235 and then Compile_Time_Known_Value (Left_Opnd (P))
5236 and then Is_False (Expr_Value (Left_Opnd (P)))
5240 -- OR ELSE with True as left operand
5242 elsif Nkind (P) = N_Or_Else
5243 and then Compile_Time_Known_Value (Left_Opnd (P))
5244 and then Is_True (Expr_Value (Left_Opnd (P)))
5248 -- (32.3) A dependent_expression of an if_expression whose associated
5249 -- condition is static and equals False.
5251 elsif Nkind (P) = N_If_Expression then
5253 Cond : constant Node_Id := First (Expressions (P));
5254 Texp : constant Node_Id := Next (Cond);
5255 Fexp : constant Node_Id := Next (Texp);
5258 if Compile_Time_Known_Value (Cond) then
5260 -- Condition is True and we are in the right operand
5262 if Is_True (Expr_Value (Cond)) and then OldP = Fexp then
5265 -- Condition is False and we are in the left operand
5267 elsif Is_False (Expr_Value (Cond)) and then OldP = Texp then
5273 -- (32.4) A condition or dependent_expression of an if_expression
5274 -- where the condition corresponding to at least one preceding
5275 -- dependent_expression of the if_expression is static and equals
5278 -- This refers to cases like
5280 -- (if True then 1 elsif 1/0=2 then 2 else 3)
5282 -- But we expand elsif's out anyway, so the above looks like:
5284 -- (if True then 1 else (if 1/0=2 then 2 else 3))
5286 -- So for us this is caught by the above check for the 32.3 case.
5288 -- (32.5) A dependent_expression of a case_expression whose
5289 -- selecting_expression is static and whose value is not covered
5290 -- by the corresponding discrete_choice_list.
5292 elsif Nkind (P) = N_Case_Expression_Alternative then
5294 -- First, we have to be in the expression to suppress messages.
5295 -- If we are within one of the choices, we want the message.
5297 if OldP = Expression (P) then
5299 -- Statically unevaluated if alternative does not match
5301 if Check_Case_Expr_Alternative (P) = No_Match then
5306 -- (32.6) A choice_expression (or a simple_expression of a range
5307 -- that occurs as a membership_choice of a membership_choice_list)
5308 -- of a static membership test that is preceded in the enclosing
5309 -- membership_choice_list by another item whose individual
5310 -- membership test (see (RM 4.5.2)) statically yields True.
5312 elsif Nkind (P) in N_Membership_Test then
5314 -- Only possibly unevaluated if simple expression is static
5316 if not Is_OK_Static_Expression (Left_Opnd (P)) then
5319 -- All members of the choice list must be static
5321 elsif (Present (Right_Opnd (P))
5322 and then not Is_OK_Static_Choice (Right_Opnd (P)))
5323 or else (Present (Alternatives (P))
5325 not Is_OK_Static_Choice_List (Alternatives (P)))
5329 -- If expression is the one and only alternative, then it is
5330 -- definitely not statically unevaluated, so we only have to
5331 -- test the case where there are alternatives present.
5333 elsif Present (Alternatives (P)) then
5335 -- Look for previous matching Choice
5337 Choice := First (Alternatives (P));
5338 while Present (Choice) loop
5340 -- If we reached us and no previous choices matched, this
5341 -- is not the case where we are statically unevaluated.
5343 exit when OldP = Choice;
5345 -- If a previous choice matches, then that is the case where
5346 -- we know our choice is statically unevaluated.
5348 if Choice_Matches (Left_Opnd (P), Choice) = Match then
5355 -- If we fall through the loop, we were not one of the choices,
5356 -- we must have been the expression, so that is not covered by
5357 -- this rule, and we keep going.
5363 -- OK, not statically unevaluated at this level, see if we should
5364 -- keep climbing to look for a higher level reason.
5366 -- Special case for component association in aggregates, where
5367 -- we want to keep climbing up to the parent aggregate.
5369 if Nkind (P) = N_Component_Association
5370 and then Nkind (Parent (P)) = N_Aggregate
5374 -- All done if not still within subexpression
5377 exit when Nkind (P) not in N_Subexpr;
5381 -- If we fall through the loop, not one of the cases covered!
5384 end Is_Statically_Unevaluated;
5386 --------------------
5387 -- Not_Null_Range --
5388 --------------------
5390 function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
5392 if Compile_Time_Known_Value (Lo)
5393 and then Compile_Time_Known_Value (Hi)
5396 Typ : Entity_Id := Etype (Lo);
5398 -- When called from the frontend, as part of the analysis of
5399 -- potentially static expressions, Typ will be the full view of a
5400 -- type with all the info needed to answer this query. When called
5401 -- from the backend, for example to know whether a range of a loop
5402 -- is null, Typ might be a private type and we need to explicitly
5403 -- switch to its corresponding full view to access the same info.
5405 if Is_Incomplete_Or_Private_Type (Typ)
5406 and then Present (Full_View (Typ))
5408 Typ := Full_View (Typ);
5411 if Is_Discrete_Type (Typ) then
5412 return Expr_Value (Lo) <= Expr_Value (Hi);
5413 else pragma Assert (Is_Real_Type (Typ));
5414 return Expr_Value_R (Lo) <= Expr_Value_R (Hi);
5427 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean is
5429 -- We allow a maximum of 500,000 bits which seems a reasonable limit
5431 if Bits < 500_000 then
5434 -- Error if this maximum is exceeded
5437 Error_Msg_N ("static value too large, capacity exceeded", N);
5446 procedure Out_Of_Range (N : Node_Id) is
5448 -- If we have the static expression case, then this is an illegality
5449 -- in Ada 95 mode, except that in an instance, we never generate an
5450 -- error (if the error is legitimate, it was already diagnosed in the
5453 if Is_Static_Expression (N)
5454 and then not In_Instance
5455 and then not In_Inlined_Body
5456 and then Ada_Version >= Ada_95
5458 -- No message if we are statically unevaluated
5460 if Is_Statically_Unevaluated (N) then
5463 -- The expression to compute the length of a packed array is attached
5464 -- to the array type itself, and deserves a separate message.
5466 elsif Nkind (Parent (N)) = N_Defining_Identifier
5467 and then Is_Array_Type (Parent (N))
5468 and then Present (Packed_Array_Impl_Type (Parent (N)))
5469 and then Present (First_Rep_Item (Parent (N)))
5472 ("length of packed array must not exceed Integer''Last",
5473 First_Rep_Item (Parent (N)));
5474 Rewrite (N, Make_Integer_Literal (Sloc (N), Uint_1));
5476 -- All cases except the special array case.
5477 -- No message if we are dealing with System.Priority values in
5478 -- CodePeer mode where the target runtime may have more priorities.
5480 elsif not CodePeer_Mode or else Etype (N) /= RTE (RE_Priority) then
5481 Apply_Compile_Time_Constraint_Error
5482 (N, "value not in range of}", CE_Range_Check_Failed);
5485 -- Here we generate a warning for the Ada 83 case, or when we are in an
5486 -- instance, or when we have a non-static expression case.
5489 Apply_Compile_Time_Constraint_Error
5490 (N, "value not in range of}??", CE_Range_Check_Failed);
5494 ----------------------
5495 -- Predicates_Match --
5496 ----------------------
5498 function Predicates_Match (T1, T2 : Entity_Id) return Boolean is
5503 if Ada_Version < Ada_2012 then
5506 -- Both types must have predicates or lack them
5508 elsif Has_Predicates (T1) /= Has_Predicates (T2) then
5511 -- Check matching predicates
5516 (T1, Name_Static_Predicate, Check_Parents => False);
5519 (T2, Name_Static_Predicate, Check_Parents => False);
5521 -- Subtypes statically match if the predicate comes from the
5522 -- same declaration, which can only happen if one is a subtype
5523 -- of the other and has no explicit predicate.
5525 -- Suppress warnings on order of actuals, which is otherwise
5526 -- triggered by one of the two calls below.
5528 pragma Warnings (Off);
5529 return Pred1 = Pred2
5530 or else (No (Pred1) and then Is_Subtype_Of (T1, T2))
5531 or else (No (Pred2) and then Is_Subtype_Of (T2, T1));
5532 pragma Warnings (On);
5534 end Predicates_Match;
5536 ---------------------------------------------
5537 -- Real_Or_String_Static_Predicate_Matches --
5538 ---------------------------------------------
5540 function Real_Or_String_Static_Predicate_Matches
5542 Typ : Entity_Id) return Boolean
5544 Expr : constant Node_Id := Static_Real_Or_String_Predicate (Typ);
5545 -- The predicate expression from the type
5547 Pfun : constant Entity_Id := Predicate_Function (Typ);
5548 -- The entity for the predicate function
5550 Ent_Name : constant Name_Id := Chars (First_Formal (Pfun));
5551 -- The name of the formal of the predicate function. Occurrences of the
5552 -- type name in Expr have been rewritten as references to this formal,
5553 -- and it has a unique name, so we can identify references by this name.
5556 -- Copy of the predicate function tree
5558 function Process (N : Node_Id) return Traverse_Result;
5559 -- Function used to process nodes during the traversal in which we will
5560 -- find occurrences of the entity name, and replace such occurrences
5561 -- by a real literal with the value to be tested.
5563 procedure Traverse is new Traverse_Proc (Process);
5564 -- The actual traversal procedure
5570 function Process (N : Node_Id) return Traverse_Result is
5572 if Nkind (N) = N_Identifier and then Chars (N) = Ent_Name then
5574 Nod : constant Node_Id := New_Copy (Val);
5576 Set_Sloc (Nod, Sloc (N));
5581 -- The predicate function may contain string-comparison operations
5582 -- that have been converted into calls to run-time array-comparison
5583 -- routines. To evaluate the predicate statically, we recover the
5584 -- original comparison operation and replace the occurrence of the
5585 -- formal by the static string value. The actuals of the generated
5586 -- call are of the form X'Address.
5588 elsif Nkind (N) in N_Op_Compare
5589 and then Nkind (Left_Opnd (N)) = N_Function_Call
5592 C : constant Node_Id := Left_Opnd (N);
5593 F : constant Node_Id := First (Parameter_Associations (C));
5594 L : constant Node_Id := Prefix (F);
5595 R : constant Node_Id := Prefix (Next (F));
5598 -- If an operand is an entity name, it is the formal of the
5599 -- predicate function, so replace it with the string value.
5600 -- It may be either operand in the call. The other operand
5601 -- is a static string from the original predicate.
5603 if Is_Entity_Name (L) then
5604 Rewrite (Left_Opnd (N), New_Copy (Val));
5605 Rewrite (Right_Opnd (N), New_Copy (R));
5608 Rewrite (Left_Opnd (N), New_Copy (L));
5609 Rewrite (Right_Opnd (N), New_Copy (Val));
5620 -- Start of processing for Real_Or_String_Static_Predicate_Matches
5623 -- First deal with special case of inherited predicate, where the
5624 -- predicate expression looks like:
5626 -- xxPredicate (typ (Ent)) and then Expr
5628 -- where Expr is the predicate expression for this level, and the
5629 -- left operand is the call to evaluate the inherited predicate.
5631 if Nkind (Expr) = N_And_Then
5632 and then Nkind (Left_Opnd (Expr)) = N_Function_Call
5633 and then Is_Predicate_Function (Entity (Name (Left_Opnd (Expr))))
5635 -- OK we have the inherited case, so make a call to evaluate the
5636 -- inherited predicate. If that fails, so do we!
5639 Real_Or_String_Static_Predicate_Matches
5641 Typ => Etype (First_Formal (Entity (Name (Left_Opnd (Expr))))))
5646 -- Use the right operand for the continued processing
5648 Copy := Copy_Separate_Tree (Right_Opnd (Expr));
5650 -- Case where call to predicate function appears on its own (this means
5651 -- that the predicate at this level is just inherited from the parent).
5653 elsif Nkind (Expr) = N_Function_Call then
5655 Typ : constant Entity_Id :=
5656 Etype (First_Formal (Entity (Name (Expr))));
5659 -- If the inherited predicate is dynamic, just ignore it. We can't
5660 -- go trying to evaluate a dynamic predicate as a static one!
5662 if Has_Dynamic_Predicate_Aspect (Typ) then
5665 -- Otherwise inherited predicate is static, check for match
5668 return Real_Or_String_Static_Predicate_Matches (Val, Typ);
5672 -- If not just an inherited predicate, copy whole expression
5675 Copy := Copy_Separate_Tree (Expr);
5678 -- Now we replace occurrences of the entity by the value
5682 -- And analyze the resulting static expression to see if it is True
5684 Analyze_And_Resolve (Copy, Standard_Boolean);
5685 return Is_True (Expr_Value (Copy));
5686 end Real_Or_String_Static_Predicate_Matches;
5688 -------------------------
5689 -- Rewrite_In_Raise_CE --
5690 -------------------------
5692 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id) is
5693 Stat : constant Boolean := Is_Static_Expression (N);
5694 Typ : constant Entity_Id := Etype (N);
5697 -- If we want to raise CE in the condition of a N_Raise_CE node, we
5698 -- can just clear the condition if the reason is appropriate. We do
5699 -- not do this operation if the parent has a reason other than range
5700 -- check failed, because otherwise we would change the reason.
5702 if Present (Parent (N))
5703 and then Nkind (Parent (N)) = N_Raise_Constraint_Error
5704 and then Reason (Parent (N)) =
5705 UI_From_Int (RT_Exception_Code'Pos (CE_Range_Check_Failed))
5707 Set_Condition (Parent (N), Empty);
5709 -- Else build an explicit N_Raise_CE
5712 if Nkind (Exp) = N_Raise_Constraint_Error then
5714 Make_Raise_Constraint_Error (Sloc (Exp),
5715 Reason => Reason (Exp)));
5718 Make_Raise_Constraint_Error (Sloc (Exp),
5719 Reason => CE_Range_Check_Failed));
5722 Set_Raises_Constraint_Error (N);
5726 -- Set proper flags in result
5728 Set_Raises_Constraint_Error (N, True);
5729 Set_Is_Static_Expression (N, Stat);
5730 end Rewrite_In_Raise_CE;
5732 ---------------------
5733 -- String_Type_Len --
5734 ---------------------
5736 function String_Type_Len (Stype : Entity_Id) return Uint is
5737 NT : constant Entity_Id := Etype (First_Index (Stype));
5741 if Is_OK_Static_Subtype (NT) then
5744 T := Base_Type (NT);
5747 return Expr_Value (Type_High_Bound (T)) -
5748 Expr_Value (Type_Low_Bound (T)) + 1;
5749 end String_Type_Len;
5751 ------------------------------------
5752 -- Subtypes_Statically_Compatible --
5753 ------------------------------------
5755 function Subtypes_Statically_Compatible
5758 Formal_Derived_Matching : Boolean := False) return Boolean
5763 if Is_Scalar_Type (T1) then
5765 -- Definitely compatible if we match
5767 if Subtypes_Statically_Match (T1, T2) then
5770 -- If either subtype is nonstatic then they're not compatible
5772 elsif not Is_OK_Static_Subtype (T1)
5774 not Is_OK_Static_Subtype (T2)
5778 -- Base types must match, but we don't check that (should we???) but
5779 -- we do at least check that both types are real, or both types are
5782 elsif Is_Real_Type (T1) /= Is_Real_Type (T2) then
5785 -- Here we check the bounds
5789 LB1 : constant Node_Id := Type_Low_Bound (T1);
5790 HB1 : constant Node_Id := Type_High_Bound (T1);
5791 LB2 : constant Node_Id := Type_Low_Bound (T2);
5792 HB2 : constant Node_Id := Type_High_Bound (T2);
5795 if Is_Real_Type (T1) then
5797 Expr_Value_R (LB1) > Expr_Value_R (HB1)
5799 (Expr_Value_R (LB2) <= Expr_Value_R (LB1)
5800 and then Expr_Value_R (HB1) <= Expr_Value_R (HB2));
5804 Expr_Value (LB1) > Expr_Value (HB1)
5806 (Expr_Value (LB2) <= Expr_Value (LB1)
5807 and then Expr_Value (HB1) <= Expr_Value (HB2));
5814 elsif Is_Access_Type (T1) then
5816 (not Is_Constrained (T2)
5817 or else Subtypes_Statically_Match
5818 (Designated_Type (T1), Designated_Type (T2)))
5819 and then not (Can_Never_Be_Null (T2)
5820 and then not Can_Never_Be_Null (T1));
5826 (Is_Composite_Type (T1) and then not Is_Constrained (T2))
5827 or else Subtypes_Statically_Match
5828 (T1, T2, Formal_Derived_Matching);
5830 end Subtypes_Statically_Compatible;
5832 -------------------------------
5833 -- Subtypes_Statically_Match --
5834 -------------------------------
5836 -- Subtypes statically match if they have statically matching constraints
5837 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
5838 -- they are the same identical constraint, or if they are static and the
5839 -- values match (RM 4.9.1(1)).
5841 -- In addition, in GNAT, the object size (Esize) values of the types must
5842 -- match if they are set (unless checking an actual for a formal derived
5843 -- type). The use of 'Object_Size can cause this to be false even if the
5844 -- types would otherwise match in the RM sense.
5846 function Subtypes_Statically_Match
5849 Formal_Derived_Matching : Boolean := False) return Boolean
5852 -- A type always statically matches itself
5857 -- No match if sizes different (from use of 'Object_Size). This test
5858 -- is excluded if Formal_Derived_Matching is True, as the base types
5859 -- can be different in that case and typically have different sizes.
5860 -- ??? Frontend_Layout_On_Target used to set Esizes but this is no
5861 -- longer the case, consider removing the last test below.
5863 elsif not Formal_Derived_Matching
5864 and then Known_Static_Esize (T1)
5865 and then Known_Static_Esize (T2)
5866 and then Esize (T1) /= Esize (T2)
5870 -- No match if predicates do not match
5872 elsif not Predicates_Match (T1, T2) then
5877 elsif Is_Scalar_Type (T1) then
5879 -- Base types must be the same
5881 if Base_Type (T1) /= Base_Type (T2) then
5885 -- A constrained numeric subtype never matches an unconstrained
5886 -- subtype, i.e. both types must be constrained or unconstrained.
5888 -- To understand the requirement for this test, see RM 4.9.1(1).
5889 -- As is made clear in RM 3.5.4(11), type Integer, for example is
5890 -- a constrained subtype with constraint bounds matching the bounds
5891 -- of its corresponding unconstrained base type. In this situation,
5892 -- Integer and Integer'Base do not statically match, even though
5893 -- they have the same bounds.
5895 -- We only apply this test to types in Standard and types that appear
5896 -- in user programs. That way, we do not have to be too careful about
5897 -- setting Is_Constrained right for Itypes.
5899 if Is_Numeric_Type (T1)
5900 and then (Is_Constrained (T1) /= Is_Constrained (T2))
5901 and then (Scope (T1) = Standard_Standard
5902 or else Comes_From_Source (T1))
5903 and then (Scope (T2) = Standard_Standard
5904 or else Comes_From_Source (T2))
5908 -- A generic scalar type does not statically match its base type
5909 -- (AI-311). In this case we make sure that the formals, which are
5910 -- first subtypes of their bases, are constrained.
5912 elsif Is_Generic_Type (T1)
5913 and then Is_Generic_Type (T2)
5914 and then (Is_Constrained (T1) /= Is_Constrained (T2))
5919 -- If there was an error in either range, then just assume the types
5920 -- statically match to avoid further junk errors.
5922 if No (Scalar_Range (T1)) or else No (Scalar_Range (T2))
5923 or else Error_Posted (Scalar_Range (T1))
5924 or else Error_Posted (Scalar_Range (T2))
5929 -- Otherwise both types have bounds that can be compared
5932 LB1 : constant Node_Id := Type_Low_Bound (T1);
5933 HB1 : constant Node_Id := Type_High_Bound (T1);
5934 LB2 : constant Node_Id := Type_Low_Bound (T2);
5935 HB2 : constant Node_Id := Type_High_Bound (T2);
5938 -- If the bounds are the same tree node, then match (common case)
5940 if LB1 = LB2 and then HB1 = HB2 then
5943 -- Otherwise bounds must be static and identical value
5946 if not Is_OK_Static_Subtype (T1)
5948 not Is_OK_Static_Subtype (T2)
5952 elsif Is_Real_Type (T1) then
5954 Expr_Value_R (LB1) = Expr_Value_R (LB2)
5956 Expr_Value_R (HB1) = Expr_Value_R (HB2);
5960 Expr_Value (LB1) = Expr_Value (LB2)
5962 Expr_Value (HB1) = Expr_Value (HB2);
5967 -- Type with discriminants
5969 elsif Has_Discriminants (T1) or else Has_Discriminants (T2) then
5971 -- Because of view exchanges in multiple instantiations, conformance
5972 -- checking might try to match a partial view of a type with no
5973 -- discriminants with a full view that has defaulted discriminants.
5974 -- In such a case, use the discriminant constraint of the full view,
5975 -- which must exist because we know that the two subtypes have the
5978 if Has_Discriminants (T1) /= Has_Discriminants (T2) then
5979 -- A generic actual type is declared through a subtype declaration
5980 -- and may have an inconsistent indication of the presence of
5981 -- discriminants, so check the type it renames.
5983 if Is_Generic_Actual_Type (T1)
5984 and then not Has_Discriminants (Etype (T1))
5985 and then not Has_Discriminants (T2)
5989 elsif In_Instance then
5990 if Is_Private_Type (T2)
5991 and then Present (Full_View (T2))
5992 and then Has_Discriminants (Full_View (T2))
5994 return Subtypes_Statically_Match (T1, Full_View (T2));
5996 elsif Is_Private_Type (T1)
5997 and then Present (Full_View (T1))
5998 and then Has_Discriminants (Full_View (T1))
6000 return Subtypes_Statically_Match (Full_View (T1), T2);
6011 DL1 : constant Elist_Id := Discriminant_Constraint (T1);
6012 DL2 : constant Elist_Id := Discriminant_Constraint (T2);
6020 elsif Is_Constrained (T1) /= Is_Constrained (T2) then
6024 -- Now loop through the discriminant constraints
6026 -- Note: the guard here seems necessary, since it is possible at
6027 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
6029 if Present (DL1) and then Present (DL2) then
6030 DA1 := First_Elmt (DL1);
6031 DA2 := First_Elmt (DL2);
6032 while Present (DA1) loop
6034 Expr1 : constant Node_Id := Node (DA1);
6035 Expr2 : constant Node_Id := Node (DA2);
6038 if not Is_OK_Static_Expression (Expr1)
6039 or else not Is_OK_Static_Expression (Expr2)
6043 -- If either expression raised a Constraint_Error,
6044 -- consider the expressions as matching, since this
6045 -- helps to prevent cascading errors.
6047 elsif Raises_Constraint_Error (Expr1)
6048 or else Raises_Constraint_Error (Expr2)
6052 elsif Expr_Value (Expr1) /= Expr_Value (Expr2) then
6065 -- A definite type does not match an indefinite or classwide type.
6066 -- However, a generic type with unknown discriminants may be
6067 -- instantiated with a type with no discriminants, and conformance
6068 -- checking on an inherited operation may compare the actual with the
6069 -- subtype that renames it in the instance.
6071 elsif Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
6074 Is_Generic_Actual_Type (T1) or else Is_Generic_Actual_Type (T2);
6078 elsif Is_Array_Type (T1) then
6080 -- If either subtype is unconstrained then both must be, and if both
6081 -- are unconstrained then no further checking is needed.
6083 if not Is_Constrained (T1) or else not Is_Constrained (T2) then
6084 return not (Is_Constrained (T1) or else Is_Constrained (T2));
6087 -- Both subtypes are constrained, so check that the index subtypes
6088 -- statically match.
6091 Index1 : Node_Id := First_Index (T1);
6092 Index2 : Node_Id := First_Index (T2);
6095 while Present (Index1) loop
6097 Subtypes_Statically_Match (Etype (Index1), Etype (Index2))
6102 Next_Index (Index1);
6103 Next_Index (Index2);
6109 elsif Is_Access_Type (T1) then
6110 if Can_Never_Be_Null (T1) /= Can_Never_Be_Null (T2) then
6113 elsif Ekind_In (T1, E_Access_Subprogram_Type,
6114 E_Anonymous_Access_Subprogram_Type)
6118 (Designated_Type (T1),
6119 Designated_Type (T2));
6122 Subtypes_Statically_Match
6123 (Designated_Type (T1),
6124 Designated_Type (T2))
6125 and then Is_Access_Constant (T1) = Is_Access_Constant (T2);
6128 -- All other types definitely match
6133 end Subtypes_Statically_Match;
6139 function Test (Cond : Boolean) return Uint is
6148 ---------------------
6149 -- Test_Comparison --
6150 ---------------------
6152 procedure Test_Comparison
6154 Assume_Valid : Boolean;
6155 True_Result : out Boolean;
6156 False_Result : out Boolean)
6158 Left : constant Node_Id := Left_Opnd (Op);
6159 Left_Typ : constant Entity_Id := Etype (Left);
6160 Orig_Op : constant Node_Id := Original_Node (Op);
6162 procedure Replacement_Warning (Msg : String);
6163 -- Emit a warning on a comparison that can be replaced by '='
6165 -------------------------
6166 -- Replacement_Warning --
6167 -------------------------
6169 procedure Replacement_Warning (Msg : String) is
6171 if Constant_Condition_Warnings
6172 and then Comes_From_Source (Orig_Op)
6173 and then Is_Integer_Type (Left_Typ)
6174 and then not Error_Posted (Op)
6175 and then not Has_Warnings_Off (Left_Typ)
6176 and then not In_Instance
6178 Error_Msg_N (Msg, Op);
6180 end Replacement_Warning;
6184 Res : constant Compare_Result :=
6185 Compile_Time_Compare (Left, Right_Opnd (Op), Assume_Valid);
6187 -- Start of processing for Test_Comparison
6190 case N_Op_Compare (Nkind (Op)) is
6192 True_Result := Res = EQ;
6193 False_Result := Res = LT or else Res = GT or else Res = NE;
6196 True_Result := Res in Compare_GE;
6197 False_Result := Res = LT;
6199 if Res = LE and then Nkind (Orig_Op) = N_Op_Ge then
6201 ("can never be greater than, could replace by ""'=""?c?");
6205 True_Result := Res = GT;
6206 False_Result := Res in Compare_LE;
6209 True_Result := Res in Compare_LE;
6210 False_Result := Res = GT;
6212 if Res = GE and then Nkind (Orig_Op) = N_Op_Le then
6214 ("can never be less than, could replace by ""'=""?c?");
6218 True_Result := Res = LT;
6219 False_Result := Res in Compare_GE;
6222 True_Result := Res = NE or else Res = GT or else Res = LT;
6223 False_Result := Res = EQ;
6225 end Test_Comparison;
6227 ---------------------------------
6228 -- Test_Expression_Is_Foldable --
6229 ---------------------------------
6233 procedure Test_Expression_Is_Foldable
6243 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
6247 -- If operand is Any_Type, just propagate to result and do not
6248 -- try to fold, this prevents cascaded errors.
6250 if Etype (Op1) = Any_Type then
6251 Set_Etype (N, Any_Type);
6254 -- If operand raises Constraint_Error, then replace node N with the
6255 -- raise Constraint_Error node, and we are obviously not foldable.
6256 -- Note that this replacement inherits the Is_Static_Expression flag
6257 -- from the operand.
6259 elsif Raises_Constraint_Error (Op1) then
6260 Rewrite_In_Raise_CE (N, Op1);
6263 -- If the operand is not static, then the result is not static, and
6264 -- all we have to do is to check the operand since it is now known
6265 -- to appear in a non-static context.
6267 elsif not Is_Static_Expression (Op1) then
6268 Check_Non_Static_Context (Op1);
6269 Fold := Compile_Time_Known_Value (Op1);
6272 -- An expression of a formal modular type is not foldable because
6273 -- the modulus is unknown.
6275 elsif Is_Modular_Integer_Type (Etype (Op1))
6276 and then Is_Generic_Type (Etype (Op1))
6278 Check_Non_Static_Context (Op1);
6281 -- Here we have the case of an operand whose type is OK, which is
6282 -- static, and which does not raise Constraint_Error, we can fold.
6285 Set_Is_Static_Expression (N);
6289 end Test_Expression_Is_Foldable;
6293 procedure Test_Expression_Is_Foldable
6299 CRT_Safe : Boolean := False)
6301 Rstat : constant Boolean := Is_Static_Expression (Op1)
6303 Is_Static_Expression (Op2);
6309 -- Inhibit folding if -gnatd.f flag set
6311 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
6315 -- If either operand is Any_Type, just propagate to result and
6316 -- do not try to fold, this prevents cascaded errors.
6318 if Etype (Op1) = Any_Type or else Etype (Op2) = Any_Type then
6319 Set_Etype (N, Any_Type);
6322 -- If left operand raises Constraint_Error, then replace node N with the
6323 -- Raise_Constraint_Error node, and we are obviously not foldable.
6324 -- Is_Static_Expression is set from the two operands in the normal way,
6325 -- and we check the right operand if it is in a non-static context.
6327 elsif Raises_Constraint_Error (Op1) then
6329 Check_Non_Static_Context (Op2);
6332 Rewrite_In_Raise_CE (N, Op1);
6333 Set_Is_Static_Expression (N, Rstat);
6336 -- Similar processing for the case of the right operand. Note that we
6337 -- don't use this routine for the short-circuit case, so we do not have
6338 -- to worry about that special case here.
6340 elsif Raises_Constraint_Error (Op2) then
6342 Check_Non_Static_Context (Op1);
6345 Rewrite_In_Raise_CE (N, Op2);
6346 Set_Is_Static_Expression (N, Rstat);
6349 -- Exclude expressions of a generic modular type, as above
6351 elsif Is_Modular_Integer_Type (Etype (Op1))
6352 and then Is_Generic_Type (Etype (Op1))
6354 Check_Non_Static_Context (Op1);
6357 -- If result is not static, then check non-static contexts on operands
6358 -- since one of them may be static and the other one may not be static.
6360 elsif not Rstat then
6361 Check_Non_Static_Context (Op1);
6362 Check_Non_Static_Context (Op2);
6365 Fold := CRT_Safe_Compile_Time_Known_Value (Op1)
6366 and then CRT_Safe_Compile_Time_Known_Value (Op2);
6368 Fold := Compile_Time_Known_Value (Op1)
6369 and then Compile_Time_Known_Value (Op2);
6374 -- Else result is static and foldable. Both operands are static, and
6375 -- neither raises Constraint_Error, so we can definitely fold.
6378 Set_Is_Static_Expression (N);
6383 end Test_Expression_Is_Foldable;
6389 function Test_In_Range
6392 Assume_Valid : Boolean;
6393 Fixed_Int : Boolean;
6394 Int_Real : Boolean) return Range_Membership
6399 pragma Warnings (Off, Assume_Valid);
6400 -- For now Assume_Valid is unreferenced since the current implementation
6401 -- always returns Unknown if N is not a compile-time-known value, but we
6402 -- keep the parameter to allow for future enhancements in which we try
6403 -- to get the information in the variable case as well.
6406 -- If an error was posted on expression, then return Unknown, we do not
6407 -- want cascaded errors based on some false analysis of a junk node.
6409 if Error_Posted (N) then
6412 -- Expression that raises Constraint_Error is an odd case. We certainly
6413 -- do not want to consider it to be in range. It might make sense to
6414 -- consider it always out of range, but this causes incorrect error
6415 -- messages about static expressions out of range. So we just return
6416 -- Unknown, which is always safe.
6418 elsif Raises_Constraint_Error (N) then
6421 -- Universal types have no range limits, so always in range
6423 elsif Typ = Universal_Integer or else Typ = Universal_Real then
6426 -- Never known if not scalar type. Don't know if this can actually
6427 -- happen, but our spec allows it, so we must check.
6429 elsif not Is_Scalar_Type (Typ) then
6432 -- Never known if this is a generic type, since the bounds of generic
6433 -- types are junk. Note that if we only checked for static expressions
6434 -- (instead of compile-time-known values) below, we would not need this
6435 -- check, because values of a generic type can never be static, but they
6436 -- can be known at compile time.
6438 elsif Is_Generic_Type (Typ) then
6441 -- Case of a known compile time value, where we can check if it is in
6442 -- the bounds of the given type.
6444 elsif Compile_Time_Known_Value (N) then
6453 Lo := Type_Low_Bound (Typ);
6454 Hi := Type_High_Bound (Typ);
6456 LB_Known := Compile_Time_Known_Value (Lo);
6457 HB_Known := Compile_Time_Known_Value (Hi);
6459 -- Fixed point types should be considered as such only if flag
6460 -- Fixed_Int is set to False.
6462 if Is_Floating_Point_Type (Typ)
6463 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
6466 Valr := Expr_Value_R (N);
6468 if LB_Known and HB_Known then
6469 if Valr >= Expr_Value_R (Lo)
6471 Valr <= Expr_Value_R (Hi)
6475 return Out_Of_Range;
6478 elsif (LB_Known and then Valr < Expr_Value_R (Lo))
6480 (HB_Known and then Valr > Expr_Value_R (Hi))
6482 return Out_Of_Range;
6489 Val := Expr_Value (N);
6491 if LB_Known and HB_Known then
6492 if Val >= Expr_Value (Lo) and then Val <= Expr_Value (Hi)
6496 return Out_Of_Range;
6499 elsif (LB_Known and then Val < Expr_Value (Lo))
6501 (HB_Known and then Val > Expr_Value (Hi))
6503 return Out_Of_Range;
6511 -- Here for value not known at compile time. Case of expression subtype
6512 -- is Typ or is a subtype of Typ, and we can assume expression is valid.
6513 -- In this case we know it is in range without knowing its value.
6516 and then (Etype (N) = Typ or else Is_Subtype_Of (Etype (N), Typ))
6520 -- Another special case. For signed integer types, if the target type
6521 -- has Is_Known_Valid set, and the source type does not have a larger
6522 -- size, then the source value must be in range. We exclude biased
6523 -- types, because they bizarrely can generate out of range values.
6525 elsif Is_Signed_Integer_Type (Etype (N))
6526 and then Is_Known_Valid (Typ)
6527 and then Esize (Etype (N)) <= Esize (Typ)
6528 and then not Has_Biased_Representation (Etype (N))
6532 -- For all other cases, result is unknown
6543 procedure To_Bits (U : Uint; B : out Bits) is
6545 for J in 0 .. B'Last loop
6546 B (J) := (U / (2 ** J)) mod 2 /= 0;
6550 --------------------
6551 -- Why_Not_Static --
6552 --------------------
6554 procedure Why_Not_Static (Expr : Node_Id) is
6555 N : constant Node_Id := Original_Node (Expr);
6556 Typ : Entity_Id := Empty;
6561 procedure Why_Not_Static_List (L : List_Id);
6562 -- A version that can be called on a list of expressions. Finds all
6563 -- non-static violations in any element of the list.
6565 -------------------------
6566 -- Why_Not_Static_List --
6567 -------------------------
6569 procedure Why_Not_Static_List (L : List_Id) is
6572 if Is_Non_Empty_List (L) then
6574 while Present (N) loop
6579 end Why_Not_Static_List;
6581 -- Start of processing for Why_Not_Static
6584 -- Ignore call on error or empty node
6586 if No (Expr) or else Nkind (Expr) = N_Error then
6590 -- Preprocessing for sub expressions
6592 if Nkind (Expr) in N_Subexpr then
6594 -- Nothing to do if expression is static
6596 if Is_OK_Static_Expression (Expr) then
6600 -- Test for Constraint_Error raised
6602 if Raises_Constraint_Error (Expr) then
6604 -- Special case membership to find out which piece to flag
6606 if Nkind (N) in N_Membership_Test then
6607 if Raises_Constraint_Error (Left_Opnd (N)) then
6608 Why_Not_Static (Left_Opnd (N));
6611 elsif Present (Right_Opnd (N))
6612 and then Raises_Constraint_Error (Right_Opnd (N))
6614 Why_Not_Static (Right_Opnd (N));
6618 pragma Assert (Present (Alternatives (N)));
6620 Alt := First (Alternatives (N));
6621 while Present (Alt) loop
6622 if Raises_Constraint_Error (Alt) then
6623 Why_Not_Static (Alt);
6631 -- Special case a range to find out which bound to flag
6633 elsif Nkind (N) = N_Range then
6634 if Raises_Constraint_Error (Low_Bound (N)) then
6635 Why_Not_Static (Low_Bound (N));
6638 elsif Raises_Constraint_Error (High_Bound (N)) then
6639 Why_Not_Static (High_Bound (N));
6643 -- Special case attribute to see which part to flag
6645 elsif Nkind (N) = N_Attribute_Reference then
6646 if Raises_Constraint_Error (Prefix (N)) then
6647 Why_Not_Static (Prefix (N));
6651 if Present (Expressions (N)) then
6652 Exp := First (Expressions (N));
6653 while Present (Exp) loop
6654 if Raises_Constraint_Error (Exp) then
6655 Why_Not_Static (Exp);
6663 -- Special case a subtype name
6665 elsif Is_Entity_Name (Expr) and then Is_Type (Entity (Expr)) then
6667 ("!& is not a static subtype (RM 4.9(26))", N, Entity (Expr));
6671 -- End of special cases
6674 ("!expression raises exception, cannot be static (RM 4.9(34))",
6679 -- If no type, then something is pretty wrong, so ignore
6681 Typ := Etype (Expr);
6687 -- Type must be scalar or string type (but allow Bignum, since this
6688 -- is really a scalar type from our point of view in this diagnosis).
6690 if not Is_Scalar_Type (Typ)
6691 and then not Is_String_Type (Typ)
6692 and then not Is_RTE (Typ, RE_Bignum)
6695 ("!static expression must have scalar or string type " &
6701 -- If we got through those checks, test particular node kind
6707 when N_Expanded_Name
6713 if Is_Named_Number (E) then
6716 elsif Ekind (E) = E_Constant then
6718 -- One case we can give a metter message is when we have a
6719 -- string literal created by concatenating an aggregate with
6720 -- an others expression.
6722 Entity_Case : declare
6723 CV : constant Node_Id := Constant_Value (E);
6724 CO : constant Node_Id := Original_Node (CV);
6726 function Is_Aggregate (N : Node_Id) return Boolean;
6727 -- See if node N came from an others aggregate, if so
6728 -- return True and set Error_Msg_Sloc to aggregate.
6734 function Is_Aggregate (N : Node_Id) return Boolean is
6736 if Nkind (Original_Node (N)) = N_Aggregate then
6737 Error_Msg_Sloc := Sloc (Original_Node (N));
6740 elsif Is_Entity_Name (N)
6741 and then Ekind (Entity (N)) = E_Constant
6743 Nkind (Original_Node (Constant_Value (Entity (N)))) =
6747 Sloc (Original_Node (Constant_Value (Entity (N))));
6755 -- Start of processing for Entity_Case
6758 if Is_Aggregate (CV)
6759 or else (Nkind (CO) = N_Op_Concat
6760 and then (Is_Aggregate (Left_Opnd (CO))
6762 Is_Aggregate (Right_Opnd (CO))))
6764 Error_Msg_N ("!aggregate (#) is never static", N);
6766 elsif No (CV) or else not Is_Static_Expression (CV) then
6768 ("!& is not a static constant (RM 4.9(5))", N, E);
6772 elsif Is_Type (E) then
6774 ("!& is not a static subtype (RM 4.9(26))", N, E);
6778 ("!& is not static constant or named number "
6779 & "(RM 4.9(5))", N, E);
6788 if Nkind (N) in N_Op_Shift then
6790 ("!shift functions are never static (RM 4.9(6,18))", N);
6792 Why_Not_Static (Left_Opnd (N));
6793 Why_Not_Static (Right_Opnd (N));
6799 Why_Not_Static (Right_Opnd (N));
6801 -- Attribute reference
6803 when N_Attribute_Reference =>
6804 Why_Not_Static_List (Expressions (N));
6806 E := Etype (Prefix (N));
6808 if E = Standard_Void_Type then
6812 -- Special case non-scalar'Size since this is a common error
6814 if Attribute_Name (N) = Name_Size then
6816 ("!size attribute is only static for static scalar type "
6817 & "(RM 4.9(7,8))", N);
6821 elsif Is_Array_Type (E) then
6822 if not Nam_In (Attribute_Name (N), Name_First,
6827 ("!static array attribute must be Length, First, or Last "
6828 & "(RM 4.9(8))", N);
6830 -- Since we know the expression is not-static (we already
6831 -- tested for this, must mean array is not static).
6835 ("!prefix is non-static array (RM 4.9(8))", Prefix (N));
6840 -- Special case generic types, since again this is a common source
6843 elsif Is_Generic_Actual_Type (E) or else Is_Generic_Type (E) then
6845 ("!attribute of generic type is never static "
6846 & "(RM 4.9(7,8))", N);
6848 elsif Is_OK_Static_Subtype (E) then
6851 elsif Is_Scalar_Type (E) then
6853 ("!prefix type for attribute is not static scalar subtype "
6854 & "(RM 4.9(7))", N);
6858 ("!static attribute must apply to array/scalar type "
6859 & "(RM 4.9(7,8))", N);
6864 when N_String_Literal =>
6866 ("!subtype of string literal is non-static (RM 4.9(4))", N);
6868 -- Explicit dereference
6870 when N_Explicit_Dereference =>
6872 ("!explicit dereference is never static (RM 4.9)", N);
6876 when N_Function_Call =>
6877 Why_Not_Static_List (Parameter_Associations (N));
6879 -- Complain about non-static function call unless we have Bignum
6880 -- which means that the underlying expression is really some
6881 -- scalar arithmetic operation.
6883 if not Is_RTE (Typ, RE_Bignum) then
6884 Error_Msg_N ("!non-static function call (RM 4.9(6,18))", N);
6887 -- Parameter assocation (test actual parameter)
6889 when N_Parameter_Association =>
6890 Why_Not_Static (Explicit_Actual_Parameter (N));
6892 -- Indexed component
6894 when N_Indexed_Component =>
6895 Error_Msg_N ("!indexed component is never static (RM 4.9)", N);
6899 when N_Procedure_Call_Statement =>
6900 Error_Msg_N ("!procedure call is never static (RM 4.9)", N);
6902 -- Qualified expression (test expression)
6904 when N_Qualified_Expression =>
6905 Why_Not_Static (Expression (N));
6910 | N_Extension_Aggregate
6912 Error_Msg_N ("!an aggregate is never static (RM 4.9)", N);
6917 Why_Not_Static (Low_Bound (N));
6918 Why_Not_Static (High_Bound (N));
6920 -- Range constraint, test range expression
6922 when N_Range_Constraint =>
6923 Why_Not_Static (Range_Expression (N));
6925 -- Subtype indication, test constraint
6927 when N_Subtype_Indication =>
6928 Why_Not_Static (Constraint (N));
6930 -- Selected component
6932 when N_Selected_Component =>
6933 Error_Msg_N ("!selected component is never static (RM 4.9)", N);
6938 Error_Msg_N ("!slice is never static (RM 4.9)", N);
6940 when N_Type_Conversion =>
6941 Why_Not_Static (Expression (N));
6943 if not Is_Scalar_Type (Entity (Subtype_Mark (N)))
6944 or else not Is_OK_Static_Subtype (Entity (Subtype_Mark (N)))
6947 ("!static conversion requires static scalar subtype result "
6948 & "(RM 4.9(9))", N);
6951 -- Unchecked type conversion
6953 when N_Unchecked_Type_Conversion =>
6955 ("!unchecked type conversion is never static (RM 4.9)", N);
6957 -- All other cases, no reason to give