1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2016, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Checks; use Checks;
28 with Debug; use Debug;
29 with Einfo; use Einfo;
30 with Elists; use Elists;
31 with Errout; use Errout;
32 with Eval_Fat; use Eval_Fat;
33 with Exp_Util; use Exp_Util;
34 with Freeze; use Freeze;
36 with Namet; use Namet;
37 with Nmake; use Nmake;
38 with Nlists; use Nlists;
40 with Par_SCO; use Par_SCO;
41 with Rtsfind; use Rtsfind;
43 with Sem_Aux; use Sem_Aux;
44 with Sem_Cat; use Sem_Cat;
45 with Sem_Ch6; use Sem_Ch6;
46 with Sem_Ch8; use Sem_Ch8;
47 with Sem_Res; use Sem_Res;
48 with Sem_Util; use Sem_Util;
49 with Sem_Type; use Sem_Type;
50 with Sem_Warn; use Sem_Warn;
51 with Sinfo; use Sinfo;
52 with Snames; use Snames;
53 with Stand; use Stand;
54 with Stringt; use Stringt;
55 with Tbuild; use Tbuild;
57 package body Sem_Eval is
59 -----------------------------------------
60 -- Handling of Compile Time Evaluation --
61 -----------------------------------------
63 -- The compile time evaluation of expressions is distributed over several
64 -- Eval_xxx procedures. These procedures are called immediately after
65 -- a subexpression is resolved and is therefore accomplished in a bottom
66 -- up fashion. The flags are synthesized using the following approach.
68 -- Is_Static_Expression is determined by following the detailed rules
69 -- in RM 4.9(4-14). This involves testing the Is_Static_Expression
70 -- flag of the operands in many cases.
72 -- Raises_Constraint_Error is set if any of the operands have the flag
73 -- set or if an attempt to compute the value of the current expression
74 -- results in detection of a runtime constraint error.
76 -- As described in the spec, the requirement is that Is_Static_Expression
77 -- be accurately set, and in addition for nodes for which this flag is set,
78 -- Raises_Constraint_Error must also be set. Furthermore a node which has
79 -- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
80 -- requirement is that the expression value must be precomputed, and the
81 -- node is either a literal, or the name of a constant entity whose value
82 -- is a static expression.
84 -- The general approach is as follows. First compute Is_Static_Expression.
85 -- If the node is not static, then the flag is left off in the node and
86 -- we are all done. Otherwise for a static node, we test if any of the
87 -- operands will raise constraint error, and if so, propagate the flag
88 -- Raises_Constraint_Error to the result node and we are done (since the
89 -- error was already posted at a lower level).
91 -- For the case of a static node whose operands do not raise constraint
92 -- error, we attempt to evaluate the node. If this evaluation succeeds,
93 -- then the node is replaced by the result of this computation. If the
94 -- evaluation raises constraint error, then we rewrite the node with
95 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
96 -- to post appropriate error messages.
102 type Bits is array (Nat range <>) of Boolean;
103 -- Used to convert unsigned (modular) values for folding logical ops
105 -- The following declarations are used to maintain a cache of nodes that
106 -- have compile time known values. The cache is maintained only for
107 -- discrete types (the most common case), and is populated by calls to
108 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
109 -- since it is possible for the status to change (in particular it is
110 -- possible for a node to get replaced by a constraint error node).
112 CV_Bits : constant := 5;
113 -- Number of low order bits of Node_Id value used to reference entries
114 -- in the cache table.
116 CV_Cache_Size : constant Nat := 2 ** CV_Bits;
117 -- Size of cache for compile time values
119 subtype CV_Range is Nat range 0 .. CV_Cache_Size;
121 type CV_Entry is record
126 type Match_Result is (Match, No_Match, Non_Static);
127 -- Result returned from functions that test for a matching result. If the
128 -- operands are not OK_Static then Non_Static will be returned. Otherwise
129 -- Match/No_Match is returned depending on whether the match succeeds.
131 type CV_Cache_Array is array (CV_Range) of CV_Entry;
133 CV_Cache : CV_Cache_Array := (others => (Node_High_Bound, Uint_0));
134 -- This is the actual cache, with entries consisting of node/value pairs,
135 -- and the impossible value Node_High_Bound used for unset entries.
137 type Range_Membership is (In_Range, Out_Of_Range, Unknown);
138 -- Range membership may either be statically known to be in range or out
139 -- of range, or not statically known. Used for Test_In_Range below.
141 -----------------------
142 -- Local Subprograms --
143 -----------------------
145 function Choice_Matches
147 Choice : Node_Id) return Match_Result;
148 -- Determines whether given value Expr matches the given Choice. The Expr
149 -- can be of discrete, real, or string type and must be a compile time
150 -- known value (it is an error to make the call if these conditions are
151 -- not met). The choice can be a range, subtype name, subtype indication,
152 -- or expression. The returned result is Non_Static if Choice is not
153 -- OK_Static, otherwise either Match or No_Match is returned depending
154 -- on whether Choice matches Expr. This is used for case expression
155 -- alternatives, and also for membership tests. In each case, more
156 -- possibilities are tested than the syntax allows (e.g. membership allows
157 -- subtype indications and non-discrete types, and case allows an OTHERS
158 -- choice), but it does not matter, since we have already done a full
159 -- semantic and syntax check of the construct, so the extra possibilities
160 -- just will not arise for correct expressions.
162 -- Note: if Choice_Matches finds that a choice raises Constraint_Error, e.g
163 -- a reference to a type, one of whose bounds raises Constraint_Error, then
164 -- it also sets the Raises_Constraint_Error flag on the Choice itself.
166 function Choices_Match
168 Choices : List_Id) return Match_Result;
169 -- This function applies Choice_Matches to each element of Choices. If the
170 -- result is No_Match, then it continues and checks the next element. If
171 -- the result is Match or Non_Static, this result is immediately given
172 -- as the result without checking the rest of the list. Expr can be of
173 -- discrete, real, or string type and must be a compile time known value
174 -- (it is an error to make the call if these conditions are not met).
176 function Find_Universal_Operator_Type (N : Node_Id) return Entity_Id;
177 -- Check whether an arithmetic operation with universal operands which is a
178 -- rewritten function call with an explicit scope indication is ambiguous:
179 -- P."+" (1, 2) will be ambiguous if there is more than one visible numeric
180 -- type declared in P and the context does not impose a type on the result
181 -- (e.g. in the expression of a type conversion). If ambiguous, emit an
182 -- error and return Empty, else return the result type of the operator.
184 function From_Bits (B : Bits; T : Entity_Id) return Uint;
185 -- Converts a bit string of length B'Length to a Uint value to be used for
186 -- a target of type T, which is a modular type. This procedure includes the
187 -- necessary reduction by the modulus in the case of a nonbinary modulus
188 -- (for a binary modulus, the bit string is the right length any way so all
191 function Get_String_Val (N : Node_Id) return Node_Id;
192 -- Given a tree node for a folded string or character value, returns the
193 -- corresponding string literal or character literal (one of the two must
194 -- be available, or the operand would not have been marked as foldable in
195 -- the earlier analysis of the operation).
197 function Is_OK_Static_Choice (Choice : Node_Id) return Boolean;
198 -- Given a choice (from a case expression or membership test), returns
199 -- True if the choice is static and does not raise a Constraint_Error.
201 function Is_OK_Static_Choice_List (Choices : List_Id) return Boolean;
202 -- Given a choice list (from a case expression or membership test), return
203 -- True if all choices are static in the sense of Is_OK_Static_Choice.
205 function Is_Static_Choice (Choice : Node_Id) return Boolean;
206 -- Given a choice (from a case expression or membership test), returns
207 -- True if the choice is static. No test is made for raising of constraint
208 -- error, so this function is used only for legality tests.
210 function Is_Static_Choice_List (Choices : List_Id) return Boolean;
211 -- Given a choice list (from a case expression or membership test), return
212 -- True if all choices are static in the sense of Is_Static_Choice.
214 function Is_Static_Range (N : Node_Id) return Boolean;
215 -- Determine if range is static, as defined in RM 4.9(26). The only allowed
216 -- argument is an N_Range node (but note that the semantic analysis of
217 -- equivalent range attribute references already turned them into the
218 -- equivalent range). This differs from Is_OK_Static_Range (which is what
219 -- must be used by clients) in that it does not care whether the bounds
220 -- raise Constraint_Error or not. Used for checking whether expressions are
221 -- static in the 4.9 sense (without worrying about exceptions).
223 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean;
224 -- Bits represents the number of bits in an integer value to be computed
225 -- (but the value has not been computed yet). If this value in Bits is
226 -- reasonable, a result of True is returned, with the implication that the
227 -- caller should go ahead and complete the calculation. If the value in
228 -- Bits is unreasonably large, then an error is posted on node N, and
229 -- False is returned (and the caller skips the proposed calculation).
231 procedure Out_Of_Range (N : Node_Id);
232 -- This procedure is called if it is determined that node N, which appears
233 -- in a non-static context, is a compile time known value which is outside
234 -- its range, i.e. the range of Etype. This is used in contexts where
235 -- this is an illegality if N is static, and should generate a warning
238 function Real_Or_String_Static_Predicate_Matches
240 Typ : Entity_Id) return Boolean;
241 -- This is the function used to evaluate real or string static predicates.
242 -- Val is an unanalyzed N_Real_Literal or N_String_Literal node, which
243 -- represents the value to be tested against the predicate. Typ is the
244 -- type with the predicate, from which the predicate expression can be
245 -- extracted. The result returned is True if the given value satisfies
248 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id);
249 -- N and Exp are nodes representing an expression, Exp is known to raise
250 -- CE. N is rewritten in term of Exp in the optimal way.
252 function String_Type_Len (Stype : Entity_Id) return Uint;
253 -- Given a string type, determines the length of the index type, or, if
254 -- this index type is non-static, the length of the base type of this index
255 -- type. Note that if the string type is itself static, then the index type
256 -- is static, so the second case applies only if the string type passed is
259 function Test (Cond : Boolean) return Uint;
260 pragma Inline (Test);
261 -- This function simply returns the appropriate Boolean'Pos value
262 -- corresponding to the value of Cond as a universal integer. It is
263 -- used for producing the result of the static evaluation of the
266 procedure Test_Expression_Is_Foldable
271 -- Tests to see if expression N whose single operand is Op1 is foldable,
272 -- i.e. the operand value is known at compile time. If the operation is
273 -- foldable, then Fold is True on return, and Stat indicates whether the
274 -- result is static (i.e. the operand was static). Note that it is quite
275 -- possible for Fold to be True, and Stat to be False, since there are
276 -- cases in which we know the value of an operand even though it is not
277 -- technically static (e.g. the static lower bound of a range whose upper
278 -- bound is non-static).
280 -- If Stat is set False on return, then Test_Expression_Is_Foldable makes
281 -- a call to Check_Non_Static_Context on the operand. If Fold is False on
282 -- return, then all processing is complete, and the caller should return,
283 -- since there is nothing else to do.
285 -- If Stat is set True on return, then Is_Static_Expression is also set
286 -- true in node N. There are some cases where this is over-enthusiastic,
287 -- e.g. in the two operand case below, for string comparison, the result is
288 -- not static even though the two operands are static. In such cases, the
289 -- caller must reset the Is_Static_Expression flag in N.
291 -- If Fold and Stat are both set to False then this routine performs also
292 -- the following extra actions:
294 -- If either operand is Any_Type then propagate it to result to prevent
297 -- If some operand raises constraint error, then replace the node N
298 -- with the raise constraint error node. This replacement inherits the
299 -- Is_Static_Expression flag from the operands.
301 procedure Test_Expression_Is_Foldable
307 CRT_Safe : Boolean := False);
308 -- Same processing, except applies to an expression N with two operands
309 -- Op1 and Op2. The result is static only if both operands are static. If
310 -- CRT_Safe is set True, then CRT_Safe_Compile_Time_Known_Value is used
311 -- for the tests that the two operands are known at compile time. See
312 -- spec of this routine for further details.
314 function Test_In_Range
317 Assume_Valid : Boolean;
319 Int_Real : Boolean) return Range_Membership;
320 -- Common processing for Is_In_Range and Is_Out_Of_Range: Returns In_Range
321 -- or Out_Of_Range if it can be guaranteed at compile time that expression
322 -- N is known to be in or out of range of the subtype Typ. If not compile
323 -- time known, Unknown is returned. See documentation of Is_In_Range for
324 -- complete description of parameters.
326 procedure To_Bits (U : Uint; B : out Bits);
327 -- Converts a Uint value to a bit string of length B'Length
329 -----------------------------------------------
330 -- Check_Expression_Against_Static_Predicate --
331 -----------------------------------------------
333 procedure Check_Expression_Against_Static_Predicate
338 -- Nothing to do if expression is not known at compile time, or the
339 -- type has no static predicate set (will be the case for all non-scalar
340 -- types, so no need to make a special test for that).
342 if not (Has_Static_Predicate (Typ)
343 and then Compile_Time_Known_Value (Expr))
348 -- Here we have a static predicate (note that it could have arisen from
349 -- an explicitly specified Dynamic_Predicate whose expression met the
350 -- rules for being predicate-static).
352 -- Case of real static predicate
354 if Is_Real_Type (Typ) then
355 if Real_Or_String_Static_Predicate_Matches
356 (Val => Make_Real_Literal (Sloc (Expr), Expr_Value_R (Expr)),
362 -- Case of string static predicate
364 elsif Is_String_Type (Typ) then
365 if Real_Or_String_Static_Predicate_Matches
366 (Val => Expr_Value_S (Expr), Typ => Typ)
371 -- Case of discrete static predicate
374 pragma Assert (Is_Discrete_Type (Typ));
376 -- If static predicate matches, nothing to do
378 if Choices_Match (Expr, Static_Discrete_Predicate (Typ)) = Match then
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)
449 and then Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True)
452 ("??float value out of range, infinity will be generated", N);
458 -- Here we have the case of outer level static expression of scalar
459 -- type, where the processing of this procedure is needed.
461 -- For real types, this is where we convert the value to a machine
462 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should only
463 -- need to do this if the parent is a constant declaration, since in
464 -- other cases, gigi should do the necessary conversion correctly, but
465 -- experimentation shows that this is not the case on all machines, in
466 -- particular if we do not convert all literals to machine values in
467 -- non-static contexts, then ACVC test C490001 fails on Sparc/Solaris
470 -- This conversion is always done by GNATprove on real literals in
471 -- non-static expressions, by calling Check_Non_Static_Context from
472 -- gnat2why, as GNATprove cannot do the conversion later contrary
473 -- to gigi. The frontend computes the information about which
474 -- expressions are static, which is used by gnat2why to call
475 -- Check_Non_Static_Context on exactly those real literals that are
476 -- not sub-expressions of static expressions.
478 if Nkind (N) = N_Real_Literal
479 and then not Is_Machine_Number (N)
480 and then not Is_Generic_Type (Etype (N))
481 and then Etype (N) /= Universal_Real
483 -- Check that value is in bounds before converting to machine
484 -- number, so as not to lose case where value overflows in the
485 -- least significant bit or less. See B490001.
487 if Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True) then
492 -- Note: we have to copy the node, to avoid problems with conformance
493 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
495 Rewrite (N, New_Copy (N));
497 if not Is_Floating_Point_Type (T) then
499 (N, Corresponding_Integer_Value (N) * Small_Value (T));
501 elsif not UR_Is_Zero (Realval (N)) then
503 -- Note: even though RM 4.9(38) specifies biased rounding, this
504 -- has been modified by AI-100 in order to prevent confusing
505 -- differences in rounding between static and non-static
506 -- expressions. AI-100 specifies that the effect of such rounding
507 -- is implementation dependent, and in GNAT we round to nearest
508 -- even to match the run-time behavior. Note that this applies
509 -- to floating point literals, not fixed points ones, even though
510 -- their compiler representation is also as a universal real.
513 (N, Machine (Base_Type (T), Realval (N), Round_Even, N));
514 Set_Is_Machine_Number (N);
519 -- Check for out of range universal integer. This is a non-static
520 -- context, so the integer value must be in range of the runtime
521 -- representation of universal integers.
523 -- We do this only within an expression, because that is the only
524 -- case in which non-static universal integer values can occur, and
525 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
526 -- called in contexts like the expression of a number declaration where
527 -- we certainly want to allow out of range values.
529 if Etype (N) = Universal_Integer
530 and then Nkind (N) = N_Integer_Literal
531 and then Nkind (Parent (N)) in N_Subexpr
533 (Intval (N) < Expr_Value (Type_Low_Bound (Universal_Integer))
535 Intval (N) > Expr_Value (Type_High_Bound (Universal_Integer)))
537 Apply_Compile_Time_Constraint_Error
538 (N, "non-static universal integer value out of range<<",
539 CE_Range_Check_Failed);
541 -- Check out of range of base type
543 elsif Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True) then
546 -- Give warning if outside subtype (where one or both of the bounds of
547 -- the subtype is static). This warning is omitted if the expression
548 -- appears in a range that could be null (warnings are handled elsewhere
551 elsif T /= Base_Type (T) and then Nkind (Parent (N)) /= N_Range then
552 if Is_In_Range (N, T, Assume_Valid => True) then
555 elsif Is_Out_Of_Range (N, T, Assume_Valid => True) then
556 Apply_Compile_Time_Constraint_Error
557 (N, "value not in range of}<<", CE_Range_Check_Failed);
560 Enable_Range_Check (N);
563 Set_Do_Range_Check (N, False);
566 end Check_Non_Static_Context;
568 ---------------------------------
569 -- Check_String_Literal_Length --
570 ---------------------------------
572 procedure Check_String_Literal_Length (N : Node_Id; Ttype : Entity_Id) is
574 if not Raises_Constraint_Error (N) and then Is_Constrained (Ttype) then
575 if UI_From_Int (String_Length (Strval (N))) /= String_Type_Len (Ttype)
577 Apply_Compile_Time_Constraint_Error
578 (N, "string length wrong for}??",
579 CE_Length_Check_Failed,
584 end Check_String_Literal_Length;
590 function Choice_Matches
592 Choice : Node_Id) return Match_Result
594 Etyp : constant Entity_Id := Etype (Expr);
600 pragma Assert (Compile_Time_Known_Value (Expr));
601 pragma Assert (Is_Scalar_Type (Etyp) or else Is_String_Type (Etyp));
603 if not Is_OK_Static_Choice (Choice) then
604 Set_Raises_Constraint_Error (Choice);
607 -- When the choice denotes a subtype with a static predictate, check the
608 -- expression against the predicate values.
610 elsif (Nkind (Choice) = N_Subtype_Indication
611 or else (Is_Entity_Name (Choice)
612 and then Is_Type (Entity (Choice))))
613 and then Has_Predicates (Etype (Choice))
614 and then Has_Static_Predicate (Etype (Choice))
617 Choices_Match (Expr, Static_Discrete_Predicate (Etype (Choice)));
619 -- Discrete type case
621 elsif Is_Discrete_Type (Etyp) then
622 Val := Expr_Value (Expr);
624 if Nkind (Choice) = N_Range then
625 if Val >= Expr_Value (Low_Bound (Choice))
627 Val <= Expr_Value (High_Bound (Choice))
634 elsif Nkind (Choice) = N_Subtype_Indication
635 or else (Is_Entity_Name (Choice) and then Is_Type (Entity (Choice)))
637 if Val >= Expr_Value (Type_Low_Bound (Etype (Choice)))
639 Val <= Expr_Value (Type_High_Bound (Etype (Choice)))
646 elsif Nkind (Choice) = N_Others_Choice then
650 if Val = Expr_Value (Choice) then
659 elsif Is_Real_Type (Etyp) then
660 ValR := Expr_Value_R (Expr);
662 if Nkind (Choice) = N_Range then
663 if ValR >= Expr_Value_R (Low_Bound (Choice))
665 ValR <= Expr_Value_R (High_Bound (Choice))
672 elsif Nkind (Choice) = N_Subtype_Indication
673 or else (Is_Entity_Name (Choice) and then Is_Type (Entity (Choice)))
675 if ValR >= Expr_Value_R (Type_Low_Bound (Etype (Choice)))
677 ValR <= Expr_Value_R (Type_High_Bound (Etype (Choice)))
685 if ValR = Expr_Value_R (Choice) then
695 pragma Assert (Is_String_Type (Etyp));
696 ValS := Expr_Value_S (Expr);
698 if Nkind (Choice) = N_Subtype_Indication
699 or else (Is_Entity_Name (Choice) and then Is_Type (Entity (Choice)))
701 if not Is_Constrained (Etype (Choice)) then
706 Typlen : constant Uint :=
707 String_Type_Len (Etype (Choice));
708 Strlen : constant Uint :=
709 UI_From_Int (String_Length (Strval (ValS)));
711 if Typlen = Strlen then
720 if String_Equal (Strval (ValS), Strval (Expr_Value_S (Choice)))
734 function Choices_Match
736 Choices : List_Id) return Match_Result
739 Result : Match_Result;
742 Choice := First (Choices);
743 while Present (Choice) loop
744 Result := Choice_Matches (Expr, Choice);
746 if Result /= No_Match then
756 --------------------------
757 -- Compile_Time_Compare --
758 --------------------------
760 function Compile_Time_Compare
762 Assume_Valid : Boolean) return Compare_Result
764 Discard : aliased Uint;
766 return Compile_Time_Compare (L, R, Discard'Access, Assume_Valid);
767 end Compile_Time_Compare;
769 function Compile_Time_Compare
772 Assume_Valid : Boolean;
773 Rec : Boolean := False) return Compare_Result
775 Ltyp : Entity_Id := Etype (L);
776 Rtyp : Entity_Id := Etype (R);
778 Discard : aliased Uint;
780 procedure Compare_Decompose
784 -- This procedure decomposes the node N into an expression node and a
785 -- signed offset, so that the value of N is equal to the value of R plus
786 -- the value V (which may be negative). If no such decomposition is
787 -- possible, then on return R is a copy of N, and V is set to zero.
789 function Compare_Fixup (N : Node_Id) return Node_Id;
790 -- This function deals with replacing 'Last and 'First references with
791 -- their corresponding type bounds, which we then can compare. The
792 -- argument is the original node, the result is the identity, unless we
793 -- have a 'Last/'First reference in which case the value returned is the
794 -- appropriate type bound.
796 function Is_Known_Valid_Operand (Opnd : Node_Id) return Boolean;
797 -- Even if the context does not assume that values are valid, some
798 -- simple cases can be recognized.
800 function Is_Same_Value (L, R : Node_Id) return Boolean;
801 -- Returns True iff L and R represent expressions that definitely have
802 -- identical (but not necessarily compile time known) values Indeed the
803 -- caller is expected to have already dealt with the cases of compile
804 -- time known values, so these are not tested here.
806 -----------------------
807 -- Compare_Decompose --
808 -----------------------
810 procedure Compare_Decompose
816 if Nkind (N) = N_Op_Add
817 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
820 V := Intval (Right_Opnd (N));
823 elsif Nkind (N) = N_Op_Subtract
824 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
827 V := UI_Negate (Intval (Right_Opnd (N)));
830 elsif Nkind (N) = N_Attribute_Reference then
831 if Attribute_Name (N) = Name_Succ then
832 R := First (Expressions (N));
836 elsif Attribute_Name (N) = Name_Pred then
837 R := First (Expressions (N));
845 end Compare_Decompose;
851 function Compare_Fixup (N : Node_Id) return Node_Id is
857 -- Fixup only required for First/Last attribute reference
859 if Nkind (N) = N_Attribute_Reference
860 and then Nam_In (Attribute_Name (N), Name_First, Name_Last)
862 Xtyp := Etype (Prefix (N));
864 -- If we have no type, then just abandon the attempt to do
865 -- a fixup, this is probably the result of some other error.
871 -- Dereference an access type
873 if Is_Access_Type (Xtyp) then
874 Xtyp := Designated_Type (Xtyp);
877 -- If we don't have an array type at this stage, something is
878 -- peculiar, e.g. another error, and we abandon the attempt at
881 if not Is_Array_Type (Xtyp) then
885 -- Ignore unconstrained array, since bounds are not meaningful
887 if not Is_Constrained (Xtyp) then
891 if Ekind (Xtyp) = E_String_Literal_Subtype then
892 if Attribute_Name (N) = Name_First then
893 return String_Literal_Low_Bound (Xtyp);
896 Make_Integer_Literal (Sloc (N),
897 Intval => Intval (String_Literal_Low_Bound (Xtyp)) +
898 String_Literal_Length (Xtyp));
902 -- Find correct index type
904 Indx := First_Index (Xtyp);
906 if Present (Expressions (N)) then
907 Subs := UI_To_Int (Expr_Value (First (Expressions (N))));
909 for J in 2 .. Subs loop
910 Indx := Next_Index (Indx);
914 Xtyp := Etype (Indx);
916 if Attribute_Name (N) = Name_First then
917 return Type_Low_Bound (Xtyp);
919 return Type_High_Bound (Xtyp);
926 ----------------------------
927 -- Is_Known_Valid_Operand --
928 ----------------------------
930 function Is_Known_Valid_Operand (Opnd : Node_Id) return Boolean is
932 return (Is_Entity_Name (Opnd)
934 (Is_Known_Valid (Entity (Opnd))
935 or else Ekind (Entity (Opnd)) = E_In_Parameter
937 (Ekind (Entity (Opnd)) in Object_Kind
938 and then Present (Current_Value (Entity (Opnd))))))
939 or else Is_OK_Static_Expression (Opnd);
940 end Is_Known_Valid_Operand;
946 function Is_Same_Value (L, R : Node_Id) return Boolean is
947 Lf : constant Node_Id := Compare_Fixup (L);
948 Rf : constant Node_Id := Compare_Fixup (R);
950 function Is_Same_Subscript (L, R : List_Id) return Boolean;
951 -- L, R are the Expressions values from two attribute nodes for First
952 -- or Last attributes. Either may be set to No_List if no expressions
953 -- are present (indicating subscript 1). The result is True if both
954 -- expressions represent the same subscript (note one case is where
955 -- one subscript is missing and the other is explicitly set to 1).
957 -----------------------
958 -- Is_Same_Subscript --
959 -----------------------
961 function Is_Same_Subscript (L, R : List_Id) return Boolean is
967 return Expr_Value (First (R)) = Uint_1;
972 return Expr_Value (First (L)) = Uint_1;
974 return Expr_Value (First (L)) = Expr_Value (First (R));
977 end Is_Same_Subscript;
979 -- Start of processing for Is_Same_Value
982 -- Values are the same if they refer to the same entity and the
983 -- entity is non-volatile. This does not however apply to Float
984 -- types, since we may have two NaN values and they should never
987 -- If the entity is a discriminant, the two expressions may be bounds
988 -- of components of objects of the same discriminated type. The
989 -- values of the discriminants are not static, and therefore the
990 -- result is unknown.
992 -- It would be better to comment individual branches of this test ???
994 if Nkind_In (Lf, N_Identifier, N_Expanded_Name)
995 and then Nkind_In (Rf, N_Identifier, N_Expanded_Name)
996 and then Entity (Lf) = Entity (Rf)
997 and then Ekind (Entity (Lf)) /= E_Discriminant
998 and then Present (Entity (Lf))
999 and then not Is_Floating_Point_Type (Etype (L))
1000 and then not Is_Volatile_Reference (L)
1001 and then not Is_Volatile_Reference (R)
1005 -- Or if they are compile time known and identical
1007 elsif Compile_Time_Known_Value (Lf)
1009 Compile_Time_Known_Value (Rf)
1010 and then Expr_Value (Lf) = Expr_Value (Rf)
1014 -- False if Nkind of the two nodes is different for remaining cases
1016 elsif Nkind (Lf) /= Nkind (Rf) then
1019 -- True if both 'First or 'Last values applying to the same entity
1020 -- (first and last don't change even if value does). Note that we
1021 -- need this even with the calls to Compare_Fixup, to handle the
1022 -- case of unconstrained array attributes where Compare_Fixup
1023 -- cannot find useful bounds.
1025 elsif Nkind (Lf) = N_Attribute_Reference
1026 and then Attribute_Name (Lf) = Attribute_Name (Rf)
1027 and then Nam_In (Attribute_Name (Lf), Name_First, Name_Last)
1028 and then Nkind_In (Prefix (Lf), N_Identifier, N_Expanded_Name)
1029 and then Nkind_In (Prefix (Rf), N_Identifier, N_Expanded_Name)
1030 and then Entity (Prefix (Lf)) = Entity (Prefix (Rf))
1031 and then Is_Same_Subscript (Expressions (Lf), Expressions (Rf))
1035 -- True if the same selected component from the same record
1037 elsif Nkind (Lf) = N_Selected_Component
1038 and then Selector_Name (Lf) = Selector_Name (Rf)
1039 and then Is_Same_Value (Prefix (Lf), Prefix (Rf))
1043 -- True if the same unary operator applied to the same operand
1045 elsif Nkind (Lf) in N_Unary_Op
1046 and then Is_Same_Value (Right_Opnd (Lf), Right_Opnd (Rf))
1050 -- True if the same binary operator applied to the same operands
1052 elsif Nkind (Lf) in N_Binary_Op
1053 and then Is_Same_Value (Left_Opnd (Lf), Left_Opnd (Rf))
1054 and then Is_Same_Value (Right_Opnd (Lf), Right_Opnd (Rf))
1058 -- All other cases, we can't tell, so return False
1065 -- Start of processing for Compile_Time_Compare
1068 Diff.all := No_Uint;
1070 -- In preanalysis mode, always return Unknown unless the expression
1071 -- is static. It is too early to be thinking we know the result of a
1072 -- comparison, save that judgment for the full analysis. This is
1073 -- particularly important in the case of pre and postconditions, which
1074 -- otherwise can be prematurely collapsed into having True or False
1075 -- conditions when this is inappropriate.
1077 if not (Full_Analysis
1078 or else (Is_OK_Static_Expression (L)
1080 Is_OK_Static_Expression (R)))
1085 -- If either operand could raise constraint error, then we cannot
1086 -- know the result at compile time (since CE may be raised).
1088 if not (Cannot_Raise_Constraint_Error (L)
1090 Cannot_Raise_Constraint_Error (R))
1095 -- Identical operands are most certainly equal
1101 -- If expressions have no types, then do not attempt to determine if
1102 -- they are the same, since something funny is going on. One case in
1103 -- which this happens is during generic template analysis, when bounds
1104 -- are not fully analyzed.
1106 if No (Ltyp) or else No (Rtyp) then
1110 -- These get reset to the base type for the case of entities where
1111 -- Is_Known_Valid is not set. This takes care of handling possible
1112 -- invalid representations using the value of the base type, in
1113 -- accordance with RM 13.9.1(10).
1115 Ltyp := Underlying_Type (Ltyp);
1116 Rtyp := Underlying_Type (Rtyp);
1118 -- Same rationale as above, but for Underlying_Type instead of Etype
1120 if No (Ltyp) or else No (Rtyp) then
1124 -- We do not attempt comparisons for packed arrays arrays represented as
1125 -- modular types, where the semantics of comparison is quite different.
1127 if Is_Packed_Array_Impl_Type (Ltyp)
1128 and then Is_Modular_Integer_Type (Ltyp)
1132 -- For access types, the only time we know the result at compile time
1133 -- (apart from identical operands, which we handled already) is if we
1134 -- know one operand is null and the other is not, or both operands are
1137 elsif Is_Access_Type (Ltyp) then
1138 if Known_Null (L) then
1139 if Known_Null (R) then
1141 elsif Known_Non_Null (R) then
1147 elsif Known_Non_Null (L) and then Known_Null (R) then
1154 -- Case where comparison involves two compile time known values
1156 elsif Compile_Time_Known_Value (L)
1158 Compile_Time_Known_Value (R)
1160 -- For the floating-point case, we have to be a little careful, since
1161 -- at compile time we are dealing with universal exact values, but at
1162 -- runtime, these will be in non-exact target form. That's why the
1163 -- returned results are LE and GE below instead of LT and GT.
1165 if Is_Floating_Point_Type (Ltyp)
1167 Is_Floating_Point_Type (Rtyp)
1170 Lo : constant Ureal := Expr_Value_R (L);
1171 Hi : constant Ureal := Expr_Value_R (R);
1182 -- For string types, we have two string literals and we proceed to
1183 -- compare them using the Ada style dictionary string comparison.
1185 elsif not Is_Scalar_Type (Ltyp) then
1187 Lstring : constant String_Id := Strval (Expr_Value_S (L));
1188 Rstring : constant String_Id := Strval (Expr_Value_S (R));
1189 Llen : constant Nat := String_Length (Lstring);
1190 Rlen : constant Nat := String_Length (Rstring);
1193 for J in 1 .. Nat'Min (Llen, Rlen) loop
1195 LC : constant Char_Code := Get_String_Char (Lstring, J);
1196 RC : constant Char_Code := Get_String_Char (Rstring, J);
1208 elsif Llen > Rlen then
1215 -- For remaining scalar cases we know exactly (note that this does
1216 -- include the fixed-point case, where we know the run time integer
1221 Lo : constant Uint := Expr_Value (L);
1222 Hi : constant Uint := Expr_Value (R);
1225 Diff.all := Hi - Lo;
1230 Diff.all := Lo - Hi;
1236 -- Cases where at least one operand is not known at compile time
1239 -- Remaining checks apply only for discrete types
1241 if not Is_Discrete_Type (Ltyp)
1243 not Is_Discrete_Type (Rtyp)
1248 -- Defend against generic types, or actually any expressions that
1249 -- contain a reference to a generic type from within a generic
1250 -- template. We don't want to do any range analysis of such
1251 -- expressions for two reasons. First, the bounds of a generic type
1252 -- itself are junk and cannot be used for any kind of analysis.
1253 -- Second, we may have a case where the range at run time is indeed
1254 -- known, but we don't want to do compile time analysis in the
1255 -- template based on that range since in an instance the value may be
1256 -- static, and able to be elaborated without reference to the bounds
1257 -- of types involved. As an example, consider:
1259 -- (F'Pos (F'Last) + 1) > Integer'Last
1261 -- The expression on the left side of > is Universal_Integer and thus
1262 -- acquires the type Integer for evaluation at run time, and at run
1263 -- time it is true that this condition is always False, but within
1264 -- an instance F may be a type with a static range greater than the
1265 -- range of Integer, and the expression statically evaluates to True.
1267 if References_Generic_Formal_Type (L)
1269 References_Generic_Formal_Type (R)
1274 -- Replace types by base types for the case of values which are not
1275 -- known to have valid representations. This takes care of properly
1276 -- dealing with invalid representations.
1278 if not Assume_Valid then
1279 if not (Is_Entity_Name (L)
1280 and then (Is_Known_Valid (Entity (L))
1281 or else Assume_No_Invalid_Values))
1283 Ltyp := Underlying_Type (Base_Type (Ltyp));
1286 if not (Is_Entity_Name (R)
1287 and then (Is_Known_Valid (Entity (R))
1288 or else Assume_No_Invalid_Values))
1290 Rtyp := Underlying_Type (Base_Type (Rtyp));
1294 -- First attempt is to decompose the expressions to extract a
1295 -- constant offset resulting from the use of any of the forms:
1302 -- Then we see if the two expressions are the same value, and if so
1303 -- the result is obtained by comparing the offsets.
1305 -- Note: the reason we do this test first is that it returns only
1306 -- decisive results (with diff set), where other tests, like the
1307 -- range test, may not be as so decisive. Consider for example
1308 -- J .. J + 1. This code can conclude LT with a difference of 1,
1309 -- even if the range of J is not known.
1318 Compare_Decompose (L, Lnode, Loffs);
1319 Compare_Decompose (R, Rnode, Roffs);
1321 if Is_Same_Value (Lnode, Rnode) then
1322 if Loffs = Roffs then
1324 elsif Loffs < Roffs then
1325 Diff.all := Roffs - Loffs;
1328 Diff.all := Loffs - Roffs;
1334 -- Next, try range analysis and see if operand ranges are disjoint
1342 -- True if each range is a single point
1345 Determine_Range (L, LOK, LLo, LHi, Assume_Valid);
1346 Determine_Range (R, ROK, RLo, RHi, Assume_Valid);
1349 Single := (LLo = LHi) and then (RLo = RHi);
1352 if Single and Assume_Valid then
1353 Diff.all := RLo - LLo;
1358 elsif RHi < LLo then
1359 if Single and Assume_Valid then
1360 Diff.all := LLo - RLo;
1365 elsif Single and then LLo = RLo then
1367 -- If the range includes a single literal and we can assume
1368 -- validity then the result is known even if an operand is
1371 if Assume_Valid then
1377 elsif LHi = RLo then
1380 elsif RHi = LLo then
1383 elsif not Is_Known_Valid_Operand (L)
1384 and then not Assume_Valid
1386 if Is_Same_Value (L, R) then
1393 -- If the range of either operand cannot be determined, nothing
1394 -- further can be inferred.
1401 -- Here is where we check for comparisons against maximum bounds of
1402 -- types, where we know that no value can be outside the bounds of
1403 -- the subtype. Note that this routine is allowed to assume that all
1404 -- expressions are within their subtype bounds. Callers wishing to
1405 -- deal with possibly invalid values must in any case take special
1406 -- steps (e.g. conversions to larger types) to avoid this kind of
1407 -- optimization, which is always considered to be valid. We do not
1408 -- attempt this optimization with generic types, since the type
1409 -- bounds may not be meaningful in this case.
1411 -- We are in danger of an infinite recursion here. It does not seem
1412 -- useful to go more than one level deep, so the parameter Rec is
1413 -- used to protect ourselves against this infinite recursion.
1417 -- See if we can get a decisive check against one operand and a
1418 -- bound of the other operand (four possible tests here). Note
1419 -- that we avoid testing junk bounds of a generic type.
1421 if not Is_Generic_Type (Rtyp) then
1422 case Compile_Time_Compare (L, Type_Low_Bound (Rtyp),
1424 Assume_Valid, Rec => True)
1426 when LT => return LT;
1427 when LE => return LE;
1428 when EQ => return LE;
1429 when others => null;
1432 case Compile_Time_Compare (L, Type_High_Bound (Rtyp),
1434 Assume_Valid, Rec => True)
1436 when GT => return GT;
1437 when GE => return GE;
1438 when EQ => return GE;
1439 when others => null;
1443 if not Is_Generic_Type (Ltyp) then
1444 case Compile_Time_Compare (Type_Low_Bound (Ltyp), R,
1446 Assume_Valid, Rec => True)
1448 when GT => return GT;
1449 when GE => return GE;
1450 when EQ => return GE;
1451 when others => null;
1454 case Compile_Time_Compare (Type_High_Bound (Ltyp), R,
1456 Assume_Valid, Rec => True)
1458 when LT => return LT;
1459 when LE => return LE;
1460 when EQ => return LE;
1461 when others => null;
1466 -- Next attempt is to see if we have an entity compared with a
1467 -- compile time known value, where there is a current value
1468 -- conditional for the entity which can tell us the result.
1472 -- Entity variable (left operand)
1475 -- Value (right operand)
1478 -- If False, we have reversed the operands
1481 -- Comparison operator kind from Get_Current_Value_Condition call
1484 -- Value from Get_Current_Value_Condition call
1489 Result : Compare_Result;
1490 -- Known result before inversion
1493 if Is_Entity_Name (L)
1494 and then Compile_Time_Known_Value (R)
1497 Val := Expr_Value (R);
1500 elsif Is_Entity_Name (R)
1501 and then Compile_Time_Known_Value (L)
1504 Val := Expr_Value (L);
1507 -- That was the last chance at finding a compile time result
1513 Get_Current_Value_Condition (Var, Op, Opn);
1515 -- That was the last chance, so if we got nothing return
1521 Opv := Expr_Value (Opn);
1523 -- We got a comparison, so we might have something interesting
1525 -- Convert LE to LT and GE to GT, just so we have fewer cases
1527 if Op = N_Op_Le then
1531 elsif Op = N_Op_Ge then
1536 -- Deal with equality case
1538 if Op = N_Op_Eq then
1541 elsif Opv < Val then
1547 -- Deal with inequality case
1549 elsif Op = N_Op_Ne then
1556 -- Deal with greater than case
1558 elsif Op = N_Op_Gt then
1561 elsif Opv = Val - 1 then
1567 -- Deal with less than case
1569 else pragma Assert (Op = N_Op_Lt);
1572 elsif Opv = Val + 1 then
1579 -- Deal with inverting result
1583 when GT => return LT;
1584 when GE => return LE;
1585 when LT => return GT;
1586 when LE => return GE;
1587 when others => return Result;
1594 end Compile_Time_Compare;
1596 -------------------------------
1597 -- Compile_Time_Known_Bounds --
1598 -------------------------------
1600 function Compile_Time_Known_Bounds (T : Entity_Id) return Boolean is
1605 if T = Any_Composite or else not Is_Array_Type (T) then
1609 Indx := First_Index (T);
1610 while Present (Indx) loop
1611 Typ := Underlying_Type (Etype (Indx));
1613 -- Never look at junk bounds of a generic type
1615 if Is_Generic_Type (Typ) then
1619 -- Otherwise check bounds for compile time known
1621 if not Compile_Time_Known_Value (Type_Low_Bound (Typ)) then
1623 elsif not Compile_Time_Known_Value (Type_High_Bound (Typ)) then
1631 end Compile_Time_Known_Bounds;
1633 ------------------------------
1634 -- Compile_Time_Known_Value --
1635 ------------------------------
1637 function Compile_Time_Known_Value (Op : Node_Id) return Boolean is
1638 K : constant Node_Kind := Nkind (Op);
1639 CV_Ent : CV_Entry renames CV_Cache (Nat (Op) mod CV_Cache_Size);
1642 -- Never known at compile time if bad type or raises constraint error
1643 -- or empty (latter case occurs only as a result of a previous error).
1646 Check_Error_Detected;
1650 or else Etype (Op) = Any_Type
1651 or else Raises_Constraint_Error (Op)
1656 -- If we have an entity name, then see if it is the name of a constant
1657 -- and if so, test the corresponding constant value, or the name of
1658 -- an enumeration literal, which is always a constant.
1660 if Present (Etype (Op)) and then Is_Entity_Name (Op) then
1662 E : constant Entity_Id := Entity (Op);
1666 -- Never known at compile time if it is a packed array value.
1667 -- We might want to try to evaluate these at compile time one
1668 -- day, but we do not make that attempt now.
1670 if Is_Packed_Array_Impl_Type (Etype (Op)) then
1674 if Ekind (E) = E_Enumeration_Literal then
1677 elsif Ekind (E) = E_Constant then
1678 V := Constant_Value (E);
1679 return Present (V) and then Compile_Time_Known_Value (V);
1683 -- We have a value, see if it is compile time known
1686 -- Integer literals are worth storing in the cache
1688 if K = N_Integer_Literal then
1690 CV_Ent.V := Intval (Op);
1693 -- Other literals and NULL are known at compile time
1696 Nkind_In (K, N_Character_Literal,
1705 -- If we fall through, not known at compile time
1709 -- If we get an exception while trying to do this test, then some error
1710 -- has occurred, and we simply say that the value is not known after all
1715 end Compile_Time_Known_Value;
1717 --------------------------------------
1718 -- Compile_Time_Known_Value_Or_Aggr --
1719 --------------------------------------
1721 function Compile_Time_Known_Value_Or_Aggr (Op : Node_Id) return Boolean is
1723 -- If we have an entity name, then see if it is the name of a constant
1724 -- and if so, test the corresponding constant value, or the name of
1725 -- an enumeration literal, which is always a constant.
1727 if Is_Entity_Name (Op) then
1729 E : constant Entity_Id := Entity (Op);
1733 if Ekind (E) = E_Enumeration_Literal then
1736 elsif Ekind (E) /= E_Constant then
1740 V := Constant_Value (E);
1742 and then Compile_Time_Known_Value_Or_Aggr (V);
1746 -- We have a value, see if it is compile time known
1749 if Compile_Time_Known_Value (Op) then
1752 elsif Nkind (Op) = N_Aggregate then
1754 if Present (Expressions (Op)) then
1758 Expr := First (Expressions (Op));
1759 while Present (Expr) loop
1760 if not Compile_Time_Known_Value_Or_Aggr (Expr) then
1769 if Present (Component_Associations (Op)) then
1774 Cass := First (Component_Associations (Op));
1775 while Present (Cass) loop
1777 Compile_Time_Known_Value_Or_Aggr (Expression (Cass))
1789 -- All other types of values are not known at compile time
1796 end Compile_Time_Known_Value_Or_Aggr;
1798 ---------------------------------------
1799 -- CRT_Safe_Compile_Time_Known_Value --
1800 ---------------------------------------
1802 function CRT_Safe_Compile_Time_Known_Value (Op : Node_Id) return Boolean is
1804 if (Configurable_Run_Time_Mode or No_Run_Time_Mode)
1805 and then not Is_OK_Static_Expression (Op)
1809 return Compile_Time_Known_Value (Op);
1811 end CRT_Safe_Compile_Time_Known_Value;
1817 -- This is only called for actuals of functions that are not predefined
1818 -- operators (which have already been rewritten as operators at this
1819 -- stage), so the call can never be folded, and all that needs doing for
1820 -- the actual is to do the check for a non-static context.
1822 procedure Eval_Actual (N : Node_Id) is
1824 Check_Non_Static_Context (N);
1827 --------------------
1828 -- Eval_Allocator --
1829 --------------------
1831 -- Allocators are never static, so all we have to do is to do the
1832 -- check for a non-static context if an expression is present.
1834 procedure Eval_Allocator (N : Node_Id) is
1835 Expr : constant Node_Id := Expression (N);
1837 if Nkind (Expr) = N_Qualified_Expression then
1838 Check_Non_Static_Context (Expression (Expr));
1842 ------------------------
1843 -- Eval_Arithmetic_Op --
1844 ------------------------
1846 -- Arithmetic operations are static functions, so the result is static
1847 -- if both operands are static (RM 4.9(7), 4.9(20)).
1849 procedure Eval_Arithmetic_Op (N : Node_Id) is
1850 Left : constant Node_Id := Left_Opnd (N);
1851 Right : constant Node_Id := Right_Opnd (N);
1852 Ltype : constant Entity_Id := Etype (Left);
1853 Rtype : constant Entity_Id := Etype (Right);
1854 Otype : Entity_Id := Empty;
1859 -- If not foldable we are done
1861 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1867 -- Otherwise attempt to fold
1869 if Is_Universal_Numeric_Type (Etype (Left))
1871 Is_Universal_Numeric_Type (Etype (Right))
1873 Otype := Find_Universal_Operator_Type (N);
1876 -- Fold for cases where both operands are of integer type
1878 if Is_Integer_Type (Ltype) and then Is_Integer_Type (Rtype) then
1880 Left_Int : constant Uint := Expr_Value (Left);
1881 Right_Int : constant Uint := Expr_Value (Right);
1887 Result := Left_Int + Right_Int;
1889 when N_Op_Subtract =>
1890 Result := Left_Int - Right_Int;
1892 when N_Op_Multiply =>
1895 (Num_Bits (Left_Int) + Num_Bits (Right_Int)))
1897 Result := Left_Int * Right_Int;
1904 -- The exception Constraint_Error is raised by integer
1905 -- division, rem and mod if the right operand is zero.
1907 if Right_Int = 0 then
1909 -- When SPARK_Mode is On, force a warning instead of
1910 -- an error in that case, as this likely corresponds
1911 -- to deactivated code.
1913 Apply_Compile_Time_Constraint_Error
1914 (N, "division by zero", CE_Divide_By_Zero,
1915 Warn => not Stat or SPARK_Mode = On);
1916 Set_Raises_Constraint_Error (N);
1919 -- Otherwise we can do the division
1922 Result := Left_Int / Right_Int;
1927 -- The exception Constraint_Error is raised by integer
1928 -- division, rem and mod if the right operand is zero.
1930 if Right_Int = 0 then
1932 -- When SPARK_Mode is On, force a warning instead of
1933 -- an error in that case, as this likely corresponds
1934 -- to deactivated code.
1936 Apply_Compile_Time_Constraint_Error
1937 (N, "mod with zero divisor", CE_Divide_By_Zero,
1938 Warn => not Stat or SPARK_Mode = On);
1942 Result := Left_Int mod Right_Int;
1947 -- The exception Constraint_Error is raised by integer
1948 -- division, rem and mod if the right operand is zero.
1950 if Right_Int = 0 then
1952 -- When SPARK_Mode is On, force a warning instead of
1953 -- an error in that case, as this likely corresponds
1954 -- to deactivated code.
1956 Apply_Compile_Time_Constraint_Error
1957 (N, "rem with zero divisor", CE_Divide_By_Zero,
1958 Warn => not Stat or SPARK_Mode = On);
1962 Result := Left_Int rem Right_Int;
1966 raise Program_Error;
1969 -- Adjust the result by the modulus if the type is a modular type
1971 if Is_Modular_Integer_Type (Ltype) then
1972 Result := Result mod Modulus (Ltype);
1974 -- For a signed integer type, check non-static overflow
1976 elsif (not Stat) and then Is_Signed_Integer_Type (Ltype) then
1978 BT : constant Entity_Id := Base_Type (Ltype);
1979 Lo : constant Uint := Expr_Value (Type_Low_Bound (BT));
1980 Hi : constant Uint := Expr_Value (Type_High_Bound (BT));
1982 if Result < Lo or else Result > Hi then
1983 Apply_Compile_Time_Constraint_Error
1984 (N, "value not in range of }??",
1985 CE_Overflow_Check_Failed,
1992 -- If we get here we can fold the result
1994 Fold_Uint (N, Result, Stat);
1997 -- Cases where at least one operand is a real. We handle the cases of
1998 -- both reals, or mixed/real integer cases (the latter happen only for
1999 -- divide and multiply, and the result is always real).
2001 elsif Is_Real_Type (Ltype) or else Is_Real_Type (Rtype) then
2008 if Is_Real_Type (Ltype) then
2009 Left_Real := Expr_Value_R (Left);
2011 Left_Real := UR_From_Uint (Expr_Value (Left));
2014 if Is_Real_Type (Rtype) then
2015 Right_Real := Expr_Value_R (Right);
2017 Right_Real := UR_From_Uint (Expr_Value (Right));
2020 if Nkind (N) = N_Op_Add then
2021 Result := Left_Real + Right_Real;
2023 elsif Nkind (N) = N_Op_Subtract then
2024 Result := Left_Real - Right_Real;
2026 elsif Nkind (N) = N_Op_Multiply then
2027 Result := Left_Real * Right_Real;
2029 else pragma Assert (Nkind (N) = N_Op_Divide);
2030 if UR_Is_Zero (Right_Real) then
2031 Apply_Compile_Time_Constraint_Error
2032 (N, "division by zero", CE_Divide_By_Zero);
2036 Result := Left_Real / Right_Real;
2039 Fold_Ureal (N, Result, Stat);
2043 -- If the operator was resolved to a specific type, make sure that type
2044 -- is frozen even if the expression is folded into a literal (which has
2045 -- a universal type).
2047 if Present (Otype) then
2048 Freeze_Before (N, Otype);
2050 end Eval_Arithmetic_Op;
2052 ----------------------------
2053 -- Eval_Character_Literal --
2054 ----------------------------
2056 -- Nothing to be done
2058 procedure Eval_Character_Literal (N : Node_Id) is
2059 pragma Warnings (Off, N);
2062 end Eval_Character_Literal;
2068 -- Static function calls are either calls to predefined operators
2069 -- with static arguments, or calls to functions that rename a literal.
2070 -- Only the latter case is handled here, predefined operators are
2071 -- constant-folded elsewhere.
2073 -- If the function is itself inherited (see 7423-001) the literal of
2074 -- the parent type must be explicitly converted to the return type
2077 procedure Eval_Call (N : Node_Id) is
2078 Loc : constant Source_Ptr := Sloc (N);
2079 Typ : constant Entity_Id := Etype (N);
2083 if Nkind (N) = N_Function_Call
2084 and then No (Parameter_Associations (N))
2085 and then Is_Entity_Name (Name (N))
2086 and then Present (Alias (Entity (Name (N))))
2087 and then Is_Enumeration_Type (Base_Type (Typ))
2089 Lit := Ultimate_Alias (Entity (Name (N)));
2091 if Ekind (Lit) = E_Enumeration_Literal then
2092 if Base_Type (Etype (Lit)) /= Base_Type (Typ) then
2094 (N, Convert_To (Typ, New_Occurrence_Of (Lit, Loc)));
2096 Rewrite (N, New_Occurrence_Of (Lit, Loc));
2104 --------------------------
2105 -- Eval_Case_Expression --
2106 --------------------------
2108 -- A conditional expression is static if all its conditions and dependent
2109 -- expressions are static. Note that we do not care if the dependent
2110 -- expressions raise CE, except for the one that will be selected.
2112 procedure Eval_Case_Expression (N : Node_Id) is
2117 Set_Is_Static_Expression (N, False);
2119 if not Is_Static_Expression (Expression (N)) then
2120 Check_Non_Static_Context (Expression (N));
2124 -- First loop, make sure all the alternatives are static expressions
2125 -- none of which raise Constraint_Error. We make the constraint error
2126 -- check because part of the legality condition for a correct static
2127 -- case expression is that the cases are covered, like any other case
2128 -- expression. And we can't do that if any of the conditions raise an
2129 -- exception, so we don't even try to evaluate if that is the case.
2131 Alt := First (Alternatives (N));
2132 while Present (Alt) loop
2134 -- The expression must be static, but we don't care at this stage
2135 -- if it raises Constraint_Error (the alternative might not match,
2136 -- in which case the expression is statically unevaluated anyway).
2138 if not Is_Static_Expression (Expression (Alt)) then
2139 Check_Non_Static_Context (Expression (Alt));
2143 -- The choices of a case always have to be static, and cannot raise
2144 -- an exception. If this condition is not met, then the expression
2145 -- is plain illegal, so just abandon evaluation attempts. No need
2146 -- to check non-static context when we have something illegal anyway.
2148 if not Is_OK_Static_Choice_List (Discrete_Choices (Alt)) then
2155 -- OK, if the above loop gets through it means that all choices are OK
2156 -- static (don't raise exceptions), so the whole case is static, and we
2157 -- can find the matching alternative.
2159 Set_Is_Static_Expression (N);
2161 -- Now to deal with propagating a possible constraint error
2163 -- If the selecting expression raises CE, propagate and we are done
2165 if Raises_Constraint_Error (Expression (N)) then
2166 Set_Raises_Constraint_Error (N);
2168 -- Otherwise we need to check the alternatives to find the matching
2169 -- one. CE's in other than the matching one are not relevant. But we
2170 -- do need to check the matching one. Unlike the first loop, we do not
2171 -- have to go all the way through, when we find the matching one, quit.
2174 Alt := First (Alternatives (N));
2177 -- We must find a match among the alternatives. If not, this must
2178 -- be due to other errors, so just ignore, leaving as non-static.
2181 Set_Is_Static_Expression (N, False);
2185 -- Otherwise loop through choices of this alternative
2187 Choice := First (Discrete_Choices (Alt));
2188 while Present (Choice) loop
2190 -- If we find a matching choice, then the Expression of this
2191 -- alternative replaces N (Raises_Constraint_Error flag is
2192 -- included, so we don't have to special case that).
2194 if Choice_Matches (Expression (N), Choice) = Match then
2195 Rewrite (N, Relocate_Node (Expression (Alt)));
2205 end Eval_Case_Expression;
2207 ------------------------
2208 -- Eval_Concatenation --
2209 ------------------------
2211 -- Concatenation is a static function, so the result is static if both
2212 -- operands are static (RM 4.9(7), 4.9(21)).
2214 procedure Eval_Concatenation (N : Node_Id) is
2215 Left : constant Node_Id := Left_Opnd (N);
2216 Right : constant Node_Id := Right_Opnd (N);
2217 C_Typ : constant Entity_Id := Root_Type (Component_Type (Etype (N)));
2222 -- Concatenation is never static in Ada 83, so if Ada 83 check operand
2223 -- non-static context.
2225 if Ada_Version = Ada_83
2226 and then Comes_From_Source (N)
2228 Check_Non_Static_Context (Left);
2229 Check_Non_Static_Context (Right);
2233 -- If not foldable we are done. In principle concatenation that yields
2234 -- any string type is static (i.e. an array type of character types).
2235 -- However, character types can include enumeration literals, and
2236 -- concatenation in that case cannot be described by a literal, so we
2237 -- only consider the operation static if the result is an array of
2238 -- (a descendant of) a predefined character type.
2240 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2242 if not (Is_Standard_Character_Type (C_Typ) and then Fold) then
2243 Set_Is_Static_Expression (N, False);
2247 -- Compile time string concatenation
2249 -- ??? Note that operands that are aggregates can be marked as static,
2250 -- so we should attempt at a later stage to fold concatenations with
2254 Left_Str : constant Node_Id := Get_String_Val (Left);
2256 Right_Str : constant Node_Id := Get_String_Val (Right);
2257 Folded_Val : String_Id;
2260 -- Establish new string literal, and store left operand. We make
2261 -- sure to use the special Start_String that takes an operand if
2262 -- the left operand is a string literal. Since this is optimized
2263 -- in the case where that is the most recently created string
2264 -- literal, we ensure efficient time/space behavior for the
2265 -- case of a concatenation of a series of string literals.
2267 if Nkind (Left_Str) = N_String_Literal then
2268 Left_Len := String_Length (Strval (Left_Str));
2270 -- If the left operand is the empty string, and the right operand
2271 -- is a string literal (the case of "" & "..."), the result is the
2272 -- value of the right operand. This optimization is important when
2273 -- Is_Folded_In_Parser, to avoid copying an enormous right
2276 if Left_Len = 0 and then Nkind (Right_Str) = N_String_Literal then
2277 Folded_Val := Strval (Right_Str);
2279 Start_String (Strval (Left_Str));
2284 Store_String_Char (UI_To_CC (Char_Literal_Value (Left_Str)));
2288 -- Now append the characters of the right operand, unless we
2289 -- optimized the "" & "..." case above.
2291 if Nkind (Right_Str) = N_String_Literal then
2292 if Left_Len /= 0 then
2293 Store_String_Chars (Strval (Right_Str));
2294 Folded_Val := End_String;
2297 Store_String_Char (UI_To_CC (Char_Literal_Value (Right_Str)));
2298 Folded_Val := End_String;
2301 Set_Is_Static_Expression (N, Stat);
2303 -- If left operand is the empty string, the result is the
2304 -- right operand, including its bounds if anomalous.
2307 and then Is_Array_Type (Etype (Right))
2308 and then Etype (Right) /= Any_String
2310 Set_Etype (N, Etype (Right));
2313 Fold_Str (N, Folded_Val, Static => Stat);
2315 end Eval_Concatenation;
2317 ----------------------
2318 -- Eval_Entity_Name --
2319 ----------------------
2321 -- This procedure is used for identifiers and expanded names other than
2322 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
2323 -- static if they denote a static constant (RM 4.9(6)) or if the name
2324 -- denotes an enumeration literal (RM 4.9(22)).
2326 procedure Eval_Entity_Name (N : Node_Id) is
2327 Def_Id : constant Entity_Id := Entity (N);
2331 -- Enumeration literals are always considered to be constants
2332 -- and cannot raise constraint error (RM 4.9(22)).
2334 if Ekind (Def_Id) = E_Enumeration_Literal then
2335 Set_Is_Static_Expression (N);
2338 -- A name is static if it denotes a static constant (RM 4.9(5)), and
2339 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
2340 -- it does not violate 10.2.1(8) here, since this is not a variable.
2342 elsif Ekind (Def_Id) = E_Constant then
2344 -- Deferred constants must always be treated as nonstatic outside the
2345 -- scope of their full view.
2347 if Present (Full_View (Def_Id))
2348 and then not In_Open_Scopes (Scope (Def_Id))
2352 Val := Constant_Value (Def_Id);
2355 if Present (Val) then
2356 Set_Is_Static_Expression
2357 (N, Is_Static_Expression (Val)
2358 and then Is_Static_Subtype (Etype (Def_Id)));
2359 Set_Raises_Constraint_Error (N, Raises_Constraint_Error (Val));
2361 if not Is_Static_Expression (N)
2362 and then not Is_Generic_Type (Etype (N))
2364 Validate_Static_Object_Name (N);
2367 -- Mark constant condition in SCOs
2370 and then Comes_From_Source (N)
2371 and then Is_Boolean_Type (Etype (Def_Id))
2372 and then Compile_Time_Known_Value (N)
2374 Set_SCO_Condition (N, Expr_Value_E (N) = Standard_True);
2381 -- Fall through if the name is not static
2383 Validate_Static_Object_Name (N);
2384 end Eval_Entity_Name;
2386 ------------------------
2387 -- Eval_If_Expression --
2388 ------------------------
2390 -- We can fold to a static expression if the condition and both dependent
2391 -- expressions are static. Otherwise, the only required processing is to do
2392 -- the check for non-static context for the then and else expressions.
2394 procedure Eval_If_Expression (N : Node_Id) is
2395 Condition : constant Node_Id := First (Expressions (N));
2396 Then_Expr : constant Node_Id := Next (Condition);
2397 Else_Expr : constant Node_Id := Next (Then_Expr);
2399 Non_Result : Node_Id;
2401 Rstat : constant Boolean :=
2402 Is_Static_Expression (Condition)
2404 Is_Static_Expression (Then_Expr)
2406 Is_Static_Expression (Else_Expr);
2407 -- True if result is static
2410 -- If result not static, nothing to do, otherwise set static result
2415 Set_Is_Static_Expression (N);
2418 -- If any operand is Any_Type, just propagate to result and do not try
2419 -- to fold, this prevents cascaded errors.
2421 if Etype (Condition) = Any_Type or else
2422 Etype (Then_Expr) = Any_Type or else
2423 Etype (Else_Expr) = Any_Type
2425 Set_Etype (N, Any_Type);
2426 Set_Is_Static_Expression (N, False);
2430 -- If condition raises constraint error then we have already signaled
2431 -- an error, and we just propagate to the result and do not fold.
2433 if Raises_Constraint_Error (Condition) then
2434 Set_Raises_Constraint_Error (N);
2438 -- Static case where we can fold. Note that we don't try to fold cases
2439 -- where the condition is known at compile time, but the result is
2440 -- non-static. This avoids possible cases of infinite recursion where
2441 -- the expander puts in a redundant test and we remove it. Instead we
2442 -- deal with these cases in the expander.
2444 -- Select result operand
2446 if Is_True (Expr_Value (Condition)) then
2447 Result := Then_Expr;
2448 Non_Result := Else_Expr;
2450 Result := Else_Expr;
2451 Non_Result := Then_Expr;
2454 -- Note that it does not matter if the non-result operand raises a
2455 -- Constraint_Error, but if the result raises constraint error then we
2456 -- replace the node with a raise constraint error. This will properly
2457 -- propagate Raises_Constraint_Error since this flag is set in Result.
2459 if Raises_Constraint_Error (Result) then
2460 Rewrite_In_Raise_CE (N, Result);
2461 Check_Non_Static_Context (Non_Result);
2463 -- Otherwise the result operand replaces the original node
2466 Rewrite (N, Relocate_Node (Result));
2467 Set_Is_Static_Expression (N);
2469 end Eval_If_Expression;
2471 ----------------------------
2472 -- Eval_Indexed_Component --
2473 ----------------------------
2475 -- Indexed components are never static, so we need to perform the check
2476 -- for non-static context on the index values. Then, we check if the
2477 -- value can be obtained at compile time, even though it is non-static.
2479 procedure Eval_Indexed_Component (N : Node_Id) is
2483 -- Check for non-static context on index values
2485 Expr := First (Expressions (N));
2486 while Present (Expr) loop
2487 Check_Non_Static_Context (Expr);
2491 -- If the indexed component appears in an object renaming declaration
2492 -- then we do not want to try to evaluate it, since in this case we
2493 -- need the identity of the array element.
2495 if Nkind (Parent (N)) = N_Object_Renaming_Declaration then
2498 -- Similarly if the indexed component appears as the prefix of an
2499 -- attribute we don't want to evaluate it, because at least for
2500 -- some cases of attributes we need the identify (e.g. Access, Size)
2502 elsif Nkind (Parent (N)) = N_Attribute_Reference then
2506 -- Note: there are other cases, such as the left side of an assignment,
2507 -- or an OUT parameter for a call, where the replacement results in the
2508 -- illegal use of a constant, But these cases are illegal in the first
2509 -- place, so the replacement, though silly, is harmless.
2511 -- Now see if this is a constant array reference
2513 if List_Length (Expressions (N)) = 1
2514 and then Is_Entity_Name (Prefix (N))
2515 and then Ekind (Entity (Prefix (N))) = E_Constant
2516 and then Present (Constant_Value (Entity (Prefix (N))))
2519 Loc : constant Source_Ptr := Sloc (N);
2520 Arr : constant Node_Id := Constant_Value (Entity (Prefix (N)));
2521 Sub : constant Node_Id := First (Expressions (N));
2527 -- Linear one's origin subscript value for array reference
2530 -- Lower bound of the first array index
2533 -- Value from constant array
2536 Atyp := Etype (Arr);
2538 if Is_Access_Type (Atyp) then
2539 Atyp := Designated_Type (Atyp);
2542 -- If we have an array type (we should have but perhaps there are
2543 -- error cases where this is not the case), then see if we can do
2544 -- a constant evaluation of the array reference.
2546 if Is_Array_Type (Atyp) and then Atyp /= Any_Composite then
2547 if Ekind (Atyp) = E_String_Literal_Subtype then
2548 Lbd := String_Literal_Low_Bound (Atyp);
2550 Lbd := Type_Low_Bound (Etype (First_Index (Atyp)));
2553 if Compile_Time_Known_Value (Sub)
2554 and then Nkind (Arr) = N_Aggregate
2555 and then Compile_Time_Known_Value (Lbd)
2556 and then Is_Discrete_Type (Component_Type (Atyp))
2558 Lin := UI_To_Int (Expr_Value (Sub) - Expr_Value (Lbd)) + 1;
2560 if List_Length (Expressions (Arr)) >= Lin then
2561 Elm := Pick (Expressions (Arr), Lin);
2563 -- If the resulting expression is compile time known,
2564 -- then we can rewrite the indexed component with this
2565 -- value, being sure to mark the result as non-static.
2566 -- We also reset the Sloc, in case this generates an
2567 -- error later on (e.g. 136'Access).
2569 if Compile_Time_Known_Value (Elm) then
2570 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
2571 Set_Is_Static_Expression (N, False);
2576 -- We can also constant-fold if the prefix is a string literal.
2577 -- This will be useful in an instantiation or an inlining.
2579 elsif Compile_Time_Known_Value (Sub)
2580 and then Nkind (Arr) = N_String_Literal
2581 and then Compile_Time_Known_Value (Lbd)
2582 and then Expr_Value (Lbd) = 1
2583 and then Expr_Value (Sub) <=
2584 String_Literal_Length (Etype (Arr))
2587 C : constant Char_Code :=
2588 Get_String_Char (Strval (Arr),
2589 UI_To_Int (Expr_Value (Sub)));
2591 Set_Character_Literal_Name (C);
2594 Make_Character_Literal (Loc,
2596 Char_Literal_Value => UI_From_CC (C));
2597 Set_Etype (Elm, Component_Type (Atyp));
2598 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
2599 Set_Is_Static_Expression (N, False);
2605 end Eval_Indexed_Component;
2607 --------------------------
2608 -- Eval_Integer_Literal --
2609 --------------------------
2611 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2612 -- as static by the analyzer. The reason we did it that early is to allow
2613 -- the possibility of turning off the Is_Static_Expression flag after
2614 -- analysis, but before resolution, when integer literals are generated in
2615 -- the expander that do not correspond to static expressions.
2617 procedure Eval_Integer_Literal (N : Node_Id) is
2618 T : constant Entity_Id := Etype (N);
2620 function In_Any_Integer_Context return Boolean;
2621 -- If the literal is resolved with a specific type in a context where
2622 -- the expected type is Any_Integer, there are no range checks on the
2623 -- literal. By the time the literal is evaluated, it carries the type
2624 -- imposed by the enclosing expression, and we must recover the context
2625 -- to determine that Any_Integer is meant.
2627 ----------------------------
2628 -- In_Any_Integer_Context --
2629 ----------------------------
2631 function In_Any_Integer_Context return Boolean is
2632 Par : constant Node_Id := Parent (N);
2633 K : constant Node_Kind := Nkind (Par);
2636 -- Any_Integer also appears in digits specifications for real types,
2637 -- but those have bounds smaller that those of any integer base type,
2638 -- so we can safely ignore these cases.
2640 return Nkind_In (K, N_Number_Declaration,
2641 N_Attribute_Reference,
2642 N_Attribute_Definition_Clause,
2643 N_Modular_Type_Definition,
2644 N_Signed_Integer_Type_Definition);
2645 end In_Any_Integer_Context;
2647 -- Start of processing for Eval_Integer_Literal
2651 -- If the literal appears in a non-expression context, then it is
2652 -- certainly appearing in a non-static context, so check it. This is
2653 -- actually a redundant check, since Check_Non_Static_Context would
2654 -- check it, but it seems worth while avoiding the call.
2656 if Nkind (Parent (N)) not in N_Subexpr
2657 and then not In_Any_Integer_Context
2659 Check_Non_Static_Context (N);
2662 -- Modular integer literals must be in their base range
2664 if Is_Modular_Integer_Type (T)
2665 and then Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True)
2669 end Eval_Integer_Literal;
2671 ---------------------
2672 -- Eval_Logical_Op --
2673 ---------------------
2675 -- Logical operations are static functions, so the result is potentially
2676 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2678 procedure Eval_Logical_Op (N : Node_Id) is
2679 Left : constant Node_Id := Left_Opnd (N);
2680 Right : constant Node_Id := Right_Opnd (N);
2685 -- If not foldable we are done
2687 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2693 -- Compile time evaluation of logical operation
2696 Left_Int : constant Uint := Expr_Value (Left);
2697 Right_Int : constant Uint := Expr_Value (Right);
2700 if Is_Modular_Integer_Type (Etype (N)) then
2702 Left_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
2703 Right_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
2706 To_Bits (Left_Int, Left_Bits);
2707 To_Bits (Right_Int, Right_Bits);
2709 -- Note: should really be able to use array ops instead of
2710 -- these loops, but they weren't working at the time ???
2712 if Nkind (N) = N_Op_And then
2713 for J in Left_Bits'Range loop
2714 Left_Bits (J) := Left_Bits (J) and Right_Bits (J);
2717 elsif Nkind (N) = N_Op_Or then
2718 for J in Left_Bits'Range loop
2719 Left_Bits (J) := Left_Bits (J) or Right_Bits (J);
2723 pragma Assert (Nkind (N) = N_Op_Xor);
2725 for J in Left_Bits'Range loop
2726 Left_Bits (J) := Left_Bits (J) xor Right_Bits (J);
2730 Fold_Uint (N, From_Bits (Left_Bits, Etype (N)), Stat);
2734 pragma Assert (Is_Boolean_Type (Etype (N)));
2736 if Nkind (N) = N_Op_And then
2738 Test (Is_True (Left_Int) and then Is_True (Right_Int)), Stat);
2740 elsif Nkind (N) = N_Op_Or then
2742 Test (Is_True (Left_Int) or else Is_True (Right_Int)), Stat);
2745 pragma Assert (Nkind (N) = N_Op_Xor);
2747 Test (Is_True (Left_Int) xor Is_True (Right_Int)), Stat);
2751 end Eval_Logical_Op;
2753 ------------------------
2754 -- Eval_Membership_Op --
2755 ------------------------
2757 -- A membership test is potentially static if the expression is static, and
2758 -- the range is a potentially static range, or is a subtype mark denoting a
2759 -- static subtype (RM 4.9(12)).
2761 procedure Eval_Membership_Op (N : Node_Id) is
2762 Alts : constant List_Id := Alternatives (N);
2763 Choice : constant Node_Id := Right_Opnd (N);
2764 Expr : constant Node_Id := Left_Opnd (N);
2765 Result : Match_Result;
2768 -- Ignore if error in either operand, except to make sure that Any_Type
2769 -- is properly propagated to avoid junk cascaded errors.
2771 if Etype (Expr) = Any_Type
2772 or else (Present (Choice) and then Etype (Choice) = Any_Type)
2774 Set_Etype (N, Any_Type);
2778 -- If left operand non-static, then nothing to do
2780 if not Is_Static_Expression (Expr) then
2784 -- If choice is non-static, left operand is in non-static context
2786 if (Present (Choice) and then not Is_Static_Choice (Choice))
2787 or else (Present (Alts) and then not Is_Static_Choice_List (Alts))
2789 Check_Non_Static_Context (Expr);
2793 -- Otherwise we definitely have a static expression
2795 Set_Is_Static_Expression (N);
2797 -- If left operand raises constraint error, propagate and we are done
2799 if Raises_Constraint_Error (Expr) then
2800 Set_Raises_Constraint_Error (N, True);
2805 if Present (Choice) then
2806 Result := Choice_Matches (Expr, Choice);
2808 Result := Choices_Match (Expr, Alts);
2811 -- If result is Non_Static, it means that we raise Constraint_Error,
2812 -- since we already tested that the operands were themselves static.
2814 if Result = Non_Static then
2815 Set_Raises_Constraint_Error (N);
2817 -- Otherwise we have our result (flipped if NOT IN case)
2821 (N, Test ((Result = Match) xor (Nkind (N) = N_Not_In)), True);
2822 Warn_On_Known_Condition (N);
2825 end Eval_Membership_Op;
2827 ------------------------
2828 -- Eval_Named_Integer --
2829 ------------------------
2831 procedure Eval_Named_Integer (N : Node_Id) is
2834 Expr_Value (Expression (Declaration_Node (Entity (N)))), True);
2835 end Eval_Named_Integer;
2837 ---------------------
2838 -- Eval_Named_Real --
2839 ---------------------
2841 procedure Eval_Named_Real (N : Node_Id) is
2844 Expr_Value_R (Expression (Declaration_Node (Entity (N)))), True);
2845 end Eval_Named_Real;
2851 -- Exponentiation is a static functions, so the result is potentially
2852 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2854 procedure Eval_Op_Expon (N : Node_Id) is
2855 Left : constant Node_Id := Left_Opnd (N);
2856 Right : constant Node_Id := Right_Opnd (N);
2861 -- If not foldable we are done
2863 Test_Expression_Is_Foldable
2864 (N, Left, Right, Stat, Fold, CRT_Safe => True);
2866 -- Return if not foldable
2872 if Configurable_Run_Time_Mode and not Stat then
2876 -- Fold exponentiation operation
2879 Right_Int : constant Uint := Expr_Value (Right);
2884 if Is_Integer_Type (Etype (Left)) then
2886 Left_Int : constant Uint := Expr_Value (Left);
2890 -- Exponentiation of an integer raises Constraint_Error for a
2891 -- negative exponent (RM 4.5.6).
2893 if Right_Int < 0 then
2894 Apply_Compile_Time_Constraint_Error
2895 (N, "integer exponent negative", CE_Range_Check_Failed,
2900 if OK_Bits (N, Num_Bits (Left_Int) * Right_Int) then
2901 Result := Left_Int ** Right_Int;
2906 if Is_Modular_Integer_Type (Etype (N)) then
2907 Result := Result mod Modulus (Etype (N));
2910 Fold_Uint (N, Result, Stat);
2918 Left_Real : constant Ureal := Expr_Value_R (Left);
2921 -- Cannot have a zero base with a negative exponent
2923 if UR_Is_Zero (Left_Real) then
2925 if Right_Int < 0 then
2926 Apply_Compile_Time_Constraint_Error
2927 (N, "zero ** negative integer", CE_Range_Check_Failed,
2931 Fold_Ureal (N, Ureal_0, Stat);
2935 Fold_Ureal (N, Left_Real ** Right_Int, Stat);
2946 -- The not operation is a static functions, so the result is potentially
2947 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
2949 procedure Eval_Op_Not (N : Node_Id) is
2950 Right : constant Node_Id := Right_Opnd (N);
2955 -- If not foldable we are done
2957 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
2963 -- Fold not operation
2966 Rint : constant Uint := Expr_Value (Right);
2967 Typ : constant Entity_Id := Etype (N);
2970 -- Negation is equivalent to subtracting from the modulus minus one.
2971 -- For a binary modulus this is equivalent to the ones-complement of
2972 -- the original value. For a nonbinary modulus this is an arbitrary
2973 -- but consistent definition.
2975 if Is_Modular_Integer_Type (Typ) then
2976 Fold_Uint (N, Modulus (Typ) - 1 - Rint, Stat);
2977 else pragma Assert (Is_Boolean_Type (Typ));
2978 Fold_Uint (N, Test (not Is_True (Rint)), Stat);
2981 Set_Is_Static_Expression (N, Stat);
2985 -------------------------------
2986 -- Eval_Qualified_Expression --
2987 -------------------------------
2989 -- A qualified expression is potentially static if its subtype mark denotes
2990 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2992 procedure Eval_Qualified_Expression (N : Node_Id) is
2993 Operand : constant Node_Id := Expression (N);
2994 Target_Type : constant Entity_Id := Entity (Subtype_Mark (N));
3001 -- Can only fold if target is string or scalar and subtype is static.
3002 -- Also, do not fold if our parent is an allocator (this is because the
3003 -- qualified expression is really part of the syntactic structure of an
3004 -- allocator, and we do not want to end up with something that
3005 -- corresponds to "new 1" where the 1 is the result of folding a
3006 -- qualified expression).
3008 if not Is_Static_Subtype (Target_Type)
3009 or else Nkind (Parent (N)) = N_Allocator
3011 Check_Non_Static_Context (Operand);
3013 -- If operand is known to raise constraint_error, set the flag on the
3014 -- expression so it does not get optimized away.
3016 if Nkind (Operand) = N_Raise_Constraint_Error then
3017 Set_Raises_Constraint_Error (N);
3023 -- If not foldable we are done
3025 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
3030 -- Don't try fold if target type has constraint error bounds
3032 elsif not Is_OK_Static_Subtype (Target_Type) then
3033 Set_Raises_Constraint_Error (N);
3037 -- Here we will fold, save Print_In_Hex indication
3039 Hex := Nkind (Operand) = N_Integer_Literal
3040 and then Print_In_Hex (Operand);
3042 -- Fold the result of qualification
3044 if Is_Discrete_Type (Target_Type) then
3045 Fold_Uint (N, Expr_Value (Operand), Stat);
3047 -- Preserve Print_In_Hex indication
3049 if Hex and then Nkind (N) = N_Integer_Literal then
3050 Set_Print_In_Hex (N);
3053 elsif Is_Real_Type (Target_Type) then
3054 Fold_Ureal (N, Expr_Value_R (Operand), Stat);
3057 Fold_Str (N, Strval (Get_String_Val (Operand)), Stat);
3060 Set_Is_Static_Expression (N, False);
3062 Check_String_Literal_Length (N, Target_Type);
3068 -- The expression may be foldable but not static
3070 Set_Is_Static_Expression (N, Stat);
3072 if Is_Out_Of_Range (N, Etype (N), Assume_Valid => True) then
3075 end Eval_Qualified_Expression;
3077 -----------------------
3078 -- Eval_Real_Literal --
3079 -----------------------
3081 -- Numeric literals are static (RM 4.9(1)), and have already been marked
3082 -- as static by the analyzer. The reason we did it that early is to allow
3083 -- the possibility of turning off the Is_Static_Expression flag after
3084 -- analysis, but before resolution, when integer literals are generated
3085 -- in the expander that do not correspond to static expressions.
3087 procedure Eval_Real_Literal (N : Node_Id) is
3088 PK : constant Node_Kind := Nkind (Parent (N));
3091 -- If the literal appears in a non-expression context and not as part of
3092 -- a number declaration, then it is appearing in a non-static context,
3095 if PK not in N_Subexpr and then PK /= N_Number_Declaration then
3096 Check_Non_Static_Context (N);
3098 end Eval_Real_Literal;
3100 ------------------------
3101 -- Eval_Relational_Op --
3102 ------------------------
3104 -- Relational operations are static functions, so the result is static if
3105 -- both operands are static (RM 4.9(7), 4.9(20)), except that for strings,
3106 -- the result is never static, even if the operands are.
3108 -- However, for internally generated nodes, we allow string equality and
3109 -- inequality to be static. This is because we rewrite A in "ABC" as an
3110 -- equality test A = "ABC", and the former is definitely static.
3112 procedure Eval_Relational_Op (N : Node_Id) is
3113 Left : constant Node_Id := Left_Opnd (N);
3114 Right : constant Node_Id := Right_Opnd (N);
3115 Typ : constant Entity_Id := Etype (Left);
3116 Otype : Entity_Id := Empty;
3120 -- One special case to deal with first. If we can tell that the result
3121 -- will be false because the lengths of one or more index subtypes are
3122 -- compile time known and different, then we can replace the entire
3123 -- result by False. We only do this for one dimensional arrays, because
3124 -- the case of multi-dimensional arrays is rare and too much trouble. If
3125 -- one of the operands is an illegal aggregate, its type might still be
3126 -- an arbitrary composite type, so nothing to do.
3128 if Is_Array_Type (Typ)
3129 and then Typ /= Any_Composite
3130 and then Number_Dimensions (Typ) = 1
3131 and then (Nkind (N) = N_Op_Eq or else Nkind (N) = N_Op_Ne)
3133 if Raises_Constraint_Error (Left)
3135 Raises_Constraint_Error (Right)
3140 -- OK, we have the case where we may be able to do this fold
3142 Length_Mismatch : declare
3143 procedure Get_Static_Length (Op : Node_Id; Len : out Uint);
3144 -- If Op is an expression for a constrained array with a known at
3145 -- compile time length, then Len is set to this (non-negative
3146 -- length). Otherwise Len is set to minus 1.
3148 -----------------------
3149 -- Get_Static_Length --
3150 -----------------------
3152 procedure Get_Static_Length (Op : Node_Id; Len : out Uint) is
3156 -- First easy case string literal
3158 if Nkind (Op) = N_String_Literal then
3159 Len := UI_From_Int (String_Length (Strval (Op)));
3163 -- Second easy case, not constrained subtype, so no length
3165 if not Is_Constrained (Etype (Op)) then
3166 Len := Uint_Minus_1;
3172 T := Etype (First_Index (Etype (Op)));
3174 -- The simple case, both bounds are known at compile time
3176 if Is_Discrete_Type (T)
3177 and then Compile_Time_Known_Value (Type_Low_Bound (T))
3178 and then Compile_Time_Known_Value (Type_High_Bound (T))
3180 Len := UI_Max (Uint_0,
3181 Expr_Value (Type_High_Bound (T)) -
3182 Expr_Value (Type_Low_Bound (T)) + 1);
3186 -- A more complex case, where the bounds are of the form
3187 -- X [+/- K1] .. X [+/- K2]), where X is an expression that is
3188 -- either A'First or A'Last (with A an entity name), or X is an
3189 -- entity name, and the two X's are the same and K1 and K2 are
3190 -- known at compile time, in this case, the length can also be
3191 -- computed at compile time, even though the bounds are not
3192 -- known. A common case of this is e.g. (X'First .. X'First+5).
3194 Extract_Length : declare
3195 procedure Decompose_Expr
3197 Ent : out Entity_Id;
3198 Kind : out Character;
3200 Orig : Boolean := True);
3201 -- Given an expression see if it is of the form given above,
3202 -- X [+/- K]. If so Ent is set to the entity in X, Kind is
3203 -- 'F','L','E' for 'First/'Last/simple entity, and Cons is
3204 -- the value of K. If the expression is not of the required
3205 -- form, Ent is set to Empty.
3207 -- Orig indicates whether Expr is the original expression
3208 -- to consider, or if we are handling a sub-expression
3209 -- (e.g. recursive call to Decompose_Expr).
3211 --------------------
3212 -- Decompose_Expr --
3213 --------------------
3215 procedure Decompose_Expr
3217 Ent : out Entity_Id;
3218 Kind : out Character;
3220 Orig : Boolean := True)
3232 if Nkind (Expr) = N_Op_Add
3233 and then Compile_Time_Known_Value (Right_Opnd (Expr))
3235 Exp := Left_Opnd (Expr);
3236 Cons := Expr_Value (Right_Opnd (Expr));
3238 elsif Nkind (Expr) = N_Op_Subtract
3239 and then Compile_Time_Known_Value (Right_Opnd (Expr))
3241 Exp := Left_Opnd (Expr);
3242 Cons := -Expr_Value (Right_Opnd (Expr));
3244 -- If the bound is a constant created to remove side
3245 -- effects, recover original expression to see if it has
3246 -- one of the recognizable forms.
3248 elsif Nkind (Expr) = N_Identifier
3249 and then not Comes_From_Source (Entity (Expr))
3250 and then Ekind (Entity (Expr)) = E_Constant
3252 Nkind (Parent (Entity (Expr))) = N_Object_Declaration
3254 Exp := Expression (Parent (Entity (Expr)));
3255 Decompose_Expr (Exp, Ent, Kind, Cons, Orig => False);
3257 -- If original expression includes an entity, create a
3258 -- reference to it for use below.
3260 if Present (Ent) then
3261 Exp := New_Occurrence_Of (Ent, Sloc (Ent));
3267 -- Only consider the case of X + 0 for a full
3268 -- expression, and not when recursing, otherwise we
3269 -- may end up with evaluating expressions not known
3270 -- at compile time to 0.
3280 -- At this stage Exp is set to the potential X
3282 if Nkind (Exp) = N_Attribute_Reference then
3283 if Attribute_Name (Exp) = Name_First then
3285 elsif Attribute_Name (Exp) = Name_Last then
3291 Exp := Prefix (Exp);
3297 if Is_Entity_Name (Exp)
3298 and then Present (Entity (Exp))
3300 Ent := Entity (Exp);
3306 Ent1, Ent2 : Entity_Id;
3307 Kind1, Kind2 : Character;
3308 Cons1, Cons2 : Uint;
3310 -- Start of processing for Extract_Length
3314 (Original_Node (Type_Low_Bound (T)), Ent1, Kind1, Cons1);
3316 (Original_Node (Type_High_Bound (T)), Ent2, Kind2, Cons2);
3319 and then Ent1 = Ent2
3320 and then Kind1 = Kind2
3322 Len := Cons2 - Cons1 + 1;
3324 Len := Uint_Minus_1;
3327 end Get_Static_Length;
3334 -- Start of processing for Length_Mismatch
3337 Get_Static_Length (Left, Len_L);
3338 Get_Static_Length (Right, Len_R);
3340 if Len_L /= Uint_Minus_1
3341 and then Len_R /= Uint_Minus_1
3342 and then Len_L /= Len_R
3344 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
3345 Warn_On_Known_Condition (N);
3348 end Length_Mismatch;
3352 Is_Static_Expression : Boolean;
3354 Is_Foldable : Boolean;
3355 pragma Unreferenced (Is_Foldable);
3358 -- Initialize the value of Is_Static_Expression. The value of
3359 -- Is_Foldable returned by Test_Expression_Is_Foldable is not needed
3360 -- since, even when some operand is a variable, we can still perform
3361 -- the static evaluation of the expression in some cases (for
3362 -- example, for a variable of a subtype of Integer we statically
3363 -- know that any value stored in such variable is smaller than
3366 Test_Expression_Is_Foldable
3367 (N, Left, Right, Is_Static_Expression, Is_Foldable);
3369 -- Only comparisons of scalars can give static results. In
3370 -- particular, comparisons of strings never yield a static
3371 -- result, even if both operands are static strings, except that
3372 -- as noted above, we allow equality/inequality for strings.
3374 if Is_String_Type (Typ)
3375 and then not Comes_From_Source (N)
3376 and then Nkind_In (N, N_Op_Eq, N_Op_Ne)
3380 elsif not Is_Scalar_Type (Typ) then
3381 Is_Static_Expression := False;
3382 Set_Is_Static_Expression (N, False);
3385 -- For operators on universal numeric types called as functions with
3386 -- an explicit scope, determine appropriate specific numeric type,
3387 -- and diagnose possible ambiguity.
3389 if Is_Universal_Numeric_Type (Etype (Left))
3391 Is_Universal_Numeric_Type (Etype (Right))
3393 Otype := Find_Universal_Operator_Type (N);
3396 -- For static real type expressions, do not use Compile_Time_Compare
3397 -- since it worries about run-time results which are not exact.
3399 if Is_Static_Expression and then Is_Real_Type (Typ) then
3401 Left_Real : constant Ureal := Expr_Value_R (Left);
3402 Right_Real : constant Ureal := Expr_Value_R (Right);
3406 when N_Op_Eq => Result := (Left_Real = Right_Real);
3407 when N_Op_Ne => Result := (Left_Real /= Right_Real);
3408 when N_Op_Lt => Result := (Left_Real < Right_Real);
3409 when N_Op_Le => Result := (Left_Real <= Right_Real);
3410 when N_Op_Gt => Result := (Left_Real > Right_Real);
3411 when N_Op_Ge => Result := (Left_Real >= Right_Real);
3414 raise Program_Error;
3417 Fold_Uint (N, Test (Result), True);
3420 -- For all other cases, we use Compile_Time_Compare to do the compare
3424 CR : constant Compare_Result :=
3425 Compile_Time_Compare
3426 (Left, Right, Assume_Valid => False);
3429 if CR = Unknown then
3437 elsif CR = NE or else CR = GT or else CR = LT then
3444 if CR = NE or else CR = GT or else CR = LT then
3455 elsif CR = EQ or else CR = GT or else CR = GE then
3462 if CR = LT or else CR = EQ or else CR = LE then
3473 elsif CR = EQ or else CR = LT or else CR = LE then
3480 if CR = GT or else CR = EQ or else CR = GE then
3489 raise Program_Error;
3493 Fold_Uint (N, Test (Result), Is_Static_Expression);
3497 -- For the case of a folded relational operator on a specific numeric
3498 -- type, freeze operand type now.
3500 if Present (Otype) then
3501 Freeze_Before (N, Otype);
3504 Warn_On_Known_Condition (N);
3505 end Eval_Relational_Op;
3511 -- Shift operations are intrinsic operations that can never be static, so
3512 -- the only processing required is to perform the required check for a non
3513 -- static context for the two operands.
3515 -- Actually we could do some compile time evaluation here some time ???
3517 procedure Eval_Shift (N : Node_Id) is
3519 Check_Non_Static_Context (Left_Opnd (N));
3520 Check_Non_Static_Context (Right_Opnd (N));
3523 ------------------------
3524 -- Eval_Short_Circuit --
3525 ------------------------
3527 -- A short circuit operation is potentially static if both operands are
3528 -- potentially static (RM 4.9 (13)).
3530 procedure Eval_Short_Circuit (N : Node_Id) is
3531 Kind : constant Node_Kind := Nkind (N);
3532 Left : constant Node_Id := Left_Opnd (N);
3533 Right : constant Node_Id := Right_Opnd (N);
3536 Rstat : constant Boolean :=
3537 Is_Static_Expression (Left)
3539 Is_Static_Expression (Right);
3542 -- Short circuit operations are never static in Ada 83
3544 if Ada_Version = Ada_83 and then Comes_From_Source (N) then
3545 Check_Non_Static_Context (Left);
3546 Check_Non_Static_Context (Right);
3550 -- Now look at the operands, we can't quite use the normal call to
3551 -- Test_Expression_Is_Foldable here because short circuit operations
3552 -- are a special case, they can still be foldable, even if the right
3553 -- operand raises constraint error.
3555 -- If either operand is Any_Type, just propagate to result and do not
3556 -- try to fold, this prevents cascaded errors.
3558 if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
3559 Set_Etype (N, Any_Type);
3562 -- If left operand raises constraint error, then replace node N with
3563 -- the raise constraint error node, and we are obviously not foldable.
3564 -- Is_Static_Expression is set from the two operands in the normal way,
3565 -- and we check the right operand if it is in a non-static context.
3567 elsif Raises_Constraint_Error (Left) then
3569 Check_Non_Static_Context (Right);
3572 Rewrite_In_Raise_CE (N, Left);
3573 Set_Is_Static_Expression (N, Rstat);
3576 -- If the result is not static, then we won't in any case fold
3578 elsif not Rstat then
3579 Check_Non_Static_Context (Left);
3580 Check_Non_Static_Context (Right);
3584 -- Here the result is static, note that, unlike the normal processing
3585 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
3586 -- the right operand raises constraint error, that's because it is not
3587 -- significant if the left operand is decisive.
3589 Set_Is_Static_Expression (N);
3591 -- It does not matter if the right operand raises constraint error if
3592 -- it will not be evaluated. So deal specially with the cases where
3593 -- the right operand is not evaluated. Note that we will fold these
3594 -- cases even if the right operand is non-static, which is fine, but
3595 -- of course in these cases the result is not potentially static.
3597 Left_Int := Expr_Value (Left);
3599 if (Kind = N_And_Then and then Is_False (Left_Int))
3601 (Kind = N_Or_Else and then Is_True (Left_Int))
3603 Fold_Uint (N, Left_Int, Rstat);
3607 -- If first operand not decisive, then it does matter if the right
3608 -- operand raises constraint error, since it will be evaluated, so
3609 -- we simply replace the node with the right operand. Note that this
3610 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
3611 -- (both are set to True in Right).
3613 if Raises_Constraint_Error (Right) then
3614 Rewrite_In_Raise_CE (N, Right);
3615 Check_Non_Static_Context (Left);
3619 -- Otherwise the result depends on the right operand
3621 Fold_Uint (N, Expr_Value (Right), Rstat);
3623 end Eval_Short_Circuit;
3629 -- Slices can never be static, so the only processing required is to check
3630 -- for non-static context if an explicit range is given.
3632 procedure Eval_Slice (N : Node_Id) is
3633 Drange : constant Node_Id := Discrete_Range (N);
3636 if Nkind (Drange) = N_Range then
3637 Check_Non_Static_Context (Low_Bound (Drange));
3638 Check_Non_Static_Context (High_Bound (Drange));
3641 -- A slice of the form A (subtype), when the subtype is the index of
3642 -- the type of A, is redundant, the slice can be replaced with A, and
3643 -- this is worth a warning.
3645 if Is_Entity_Name (Prefix (N)) then
3647 E : constant Entity_Id := Entity (Prefix (N));
3648 T : constant Entity_Id := Etype (E);
3651 if Ekind (E) = E_Constant
3652 and then Is_Array_Type (T)
3653 and then Is_Entity_Name (Drange)
3655 if Is_Entity_Name (Original_Node (First_Index (T)))
3656 and then Entity (Original_Node (First_Index (T)))
3659 if Warn_On_Redundant_Constructs then
3660 Error_Msg_N ("redundant slice denotes whole array?r?", N);
3663 -- The following might be a useful optimization???
3665 -- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
3672 -------------------------
3673 -- Eval_String_Literal --
3674 -------------------------
3676 procedure Eval_String_Literal (N : Node_Id) is
3677 Typ : constant Entity_Id := Etype (N);
3678 Bas : constant Entity_Id := Base_Type (Typ);
3684 -- Nothing to do if error type (handles cases like default expressions
3685 -- or generics where we have not yet fully resolved the type).
3687 if Bas = Any_Type or else Bas = Any_String then
3691 -- String literals are static if the subtype is static (RM 4.9(2)), so
3692 -- reset the static expression flag (it was set unconditionally in
3693 -- Analyze_String_Literal) if the subtype is non-static. We tell if
3694 -- the subtype is static by looking at the lower bound.
3696 if Ekind (Typ) = E_String_Literal_Subtype then
3697 if not Is_OK_Static_Expression (String_Literal_Low_Bound (Typ)) then
3698 Set_Is_Static_Expression (N, False);
3702 -- Here if Etype of string literal is normal Etype (not yet possible,
3703 -- but may be possible in future).
3705 elsif not Is_OK_Static_Expression
3706 (Type_Low_Bound (Etype (First_Index (Typ))))
3708 Set_Is_Static_Expression (N, False);
3712 -- If original node was a type conversion, then result if non-static
3714 if Nkind (Original_Node (N)) = N_Type_Conversion then
3715 Set_Is_Static_Expression (N, False);
3719 -- Test for illegal Ada 95 cases. A string literal is illegal in Ada 95
3720 -- if its bounds are outside the index base type and this index type is
3721 -- static. This can happen in only two ways. Either the string literal
3722 -- is too long, or it is null, and the lower bound is type'First. Either
3723 -- way it is the upper bound that is out of range of the index type.
3725 if Ada_Version >= Ada_95 then
3726 if Is_Standard_String_Type (Bas) then
3727 Xtp := Standard_Positive;
3729 Xtp := Etype (First_Index (Bas));
3732 if Ekind (Typ) = E_String_Literal_Subtype then
3733 Lo := String_Literal_Low_Bound (Typ);
3735 Lo := Type_Low_Bound (Etype (First_Index (Typ)));
3738 -- Check for string too long
3740 Len := String_Length (Strval (N));
3742 if UI_From_Int (Len) > String_Type_Len (Bas) then
3744 -- Issue message. Note that this message is a warning if the
3745 -- string literal is not marked as static (happens in some cases
3746 -- of folding strings known at compile time, but not static).
3747 -- Furthermore in such cases, we reword the message, since there
3748 -- is no string literal in the source program.
3750 if Is_Static_Expression (N) then
3751 Apply_Compile_Time_Constraint_Error
3752 (N, "string literal too long for}", CE_Length_Check_Failed,
3754 Typ => First_Subtype (Bas));
3756 Apply_Compile_Time_Constraint_Error
3757 (N, "string value too long for}", CE_Length_Check_Failed,
3759 Typ => First_Subtype (Bas),
3763 -- Test for null string not allowed
3766 and then not Is_Generic_Type (Xtp)
3768 Expr_Value (Lo) = Expr_Value (Type_Low_Bound (Base_Type (Xtp)))
3770 -- Same specialization of message
3772 if Is_Static_Expression (N) then
3773 Apply_Compile_Time_Constraint_Error
3774 (N, "null string literal not allowed for}",
3775 CE_Length_Check_Failed,
3777 Typ => First_Subtype (Bas));
3779 Apply_Compile_Time_Constraint_Error
3780 (N, "null string value not allowed for}",
3781 CE_Length_Check_Failed,
3783 Typ => First_Subtype (Bas),
3788 end Eval_String_Literal;
3790 --------------------------
3791 -- Eval_Type_Conversion --
3792 --------------------------
3794 -- A type conversion is potentially static if its subtype mark is for a
3795 -- static scalar subtype, and its operand expression is potentially static
3798 procedure Eval_Type_Conversion (N : Node_Id) is
3799 Operand : constant Node_Id := Expression (N);
3800 Source_Type : constant Entity_Id := Etype (Operand);
3801 Target_Type : constant Entity_Id := Etype (N);
3803 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean;
3804 -- Returns true if type T is an integer type, or if it is a fixed-point
3805 -- type to be treated as an integer (i.e. the flag Conversion_OK is set
3806 -- on the conversion node).
3808 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean;
3809 -- Returns true if type T is a floating-point type, or if it is a
3810 -- fixed-point type that is not to be treated as an integer (i.e. the
3811 -- flag Conversion_OK is not set on the conversion node).
3813 ------------------------------
3814 -- To_Be_Treated_As_Integer --
3815 ------------------------------
3817 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean is
3821 or else (Is_Fixed_Point_Type (T) and then Conversion_OK (N));
3822 end To_Be_Treated_As_Integer;
3824 ---------------------------
3825 -- To_Be_Treated_As_Real --
3826 ---------------------------
3828 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean is
3831 Is_Floating_Point_Type (T)
3832 or else (Is_Fixed_Point_Type (T) and then not Conversion_OK (N));
3833 end To_Be_Treated_As_Real;
3840 -- Start of processing for Eval_Type_Conversion
3843 -- Cannot fold if target type is non-static or if semantic error
3845 if not Is_Static_Subtype (Target_Type) then
3846 Check_Non_Static_Context (Operand);
3848 elsif Error_Posted (N) then
3852 -- If not foldable we are done
3854 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
3859 -- Don't try fold if target type has constraint error bounds
3861 elsif not Is_OK_Static_Subtype (Target_Type) then
3862 Set_Raises_Constraint_Error (N);
3866 -- Remaining processing depends on operand types. Note that in the
3867 -- following type test, fixed-point counts as real unless the flag
3868 -- Conversion_OK is set, in which case it counts as integer.
3870 -- Fold conversion, case of string type. The result is not static
3872 if Is_String_Type (Target_Type) then
3873 Fold_Str (N, Strval (Get_String_Val (Operand)), Static => False);
3876 -- Fold conversion, case of integer target type
3878 elsif To_Be_Treated_As_Integer (Target_Type) then
3883 -- Integer to integer conversion
3885 if To_Be_Treated_As_Integer (Source_Type) then
3886 Result := Expr_Value (Operand);
3888 -- Real to integer conversion
3891 Result := UR_To_Uint (Expr_Value_R (Operand));
3894 -- If fixed-point type (Conversion_OK must be set), then the
3895 -- result is logically an integer, but we must replace the
3896 -- conversion with the corresponding real literal, since the
3897 -- type from a semantic point of view is still fixed-point.
3899 if Is_Fixed_Point_Type (Target_Type) then
3901 (N, UR_From_Uint (Result) * Small_Value (Target_Type), Stat);
3903 -- Otherwise result is integer literal
3906 Fold_Uint (N, Result, Stat);
3910 -- Fold conversion, case of real target type
3912 elsif To_Be_Treated_As_Real (Target_Type) then
3917 if To_Be_Treated_As_Real (Source_Type) then
3918 Result := Expr_Value_R (Operand);
3920 Result := UR_From_Uint (Expr_Value (Operand));
3923 Fold_Ureal (N, Result, Stat);
3926 -- Enumeration types
3929 Fold_Uint (N, Expr_Value (Operand), Stat);
3932 if Is_Out_Of_Range (N, Etype (N), Assume_Valid => True) then
3936 end Eval_Type_Conversion;
3942 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
3943 -- are potentially static if the operand is potentially static (RM 4.9(7)).
3945 procedure Eval_Unary_Op (N : Node_Id) is
3946 Right : constant Node_Id := Right_Opnd (N);
3947 Otype : Entity_Id := Empty;
3952 -- If not foldable we are done
3954 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
3960 if Etype (Right) = Universal_Integer
3962 Etype (Right) = Universal_Real
3964 Otype := Find_Universal_Operator_Type (N);
3967 -- Fold for integer case
3969 if Is_Integer_Type (Etype (N)) then
3971 Rint : constant Uint := Expr_Value (Right);
3975 -- In the case of modular unary plus and abs there is no need
3976 -- to adjust the result of the operation since if the original
3977 -- operand was in bounds the result will be in the bounds of the
3978 -- modular type. However, in the case of modular unary minus the
3979 -- result may go out of the bounds of the modular type and needs
3982 if Nkind (N) = N_Op_Plus then
3985 elsif Nkind (N) = N_Op_Minus then
3986 if Is_Modular_Integer_Type (Etype (N)) then
3987 Result := (-Rint) mod Modulus (Etype (N));
3993 pragma Assert (Nkind (N) = N_Op_Abs);
3997 Fold_Uint (N, Result, Stat);
4000 -- Fold for real case
4002 elsif Is_Real_Type (Etype (N)) then
4004 Rreal : constant Ureal := Expr_Value_R (Right);
4008 if Nkind (N) = N_Op_Plus then
4010 elsif Nkind (N) = N_Op_Minus then
4011 Result := UR_Negate (Rreal);
4013 pragma Assert (Nkind (N) = N_Op_Abs);
4014 Result := abs Rreal;
4017 Fold_Ureal (N, Result, Stat);
4021 -- If the operator was resolved to a specific type, make sure that type
4022 -- is frozen even if the expression is folded into a literal (which has
4023 -- a universal type).
4025 if Present (Otype) then
4026 Freeze_Before (N, Otype);
4030 -------------------------------
4031 -- Eval_Unchecked_Conversion --
4032 -------------------------------
4034 -- Unchecked conversions can never be static, so the only required
4035 -- processing is to check for a non-static context for the operand.
4037 procedure Eval_Unchecked_Conversion (N : Node_Id) is
4039 Check_Non_Static_Context (Expression (N));
4040 end Eval_Unchecked_Conversion;
4042 --------------------
4043 -- Expr_Rep_Value --
4044 --------------------
4046 function Expr_Rep_Value (N : Node_Id) return Uint is
4047 Kind : constant Node_Kind := Nkind (N);
4051 if Is_Entity_Name (N) then
4054 -- An enumeration literal that was either in the source or created
4055 -- as a result of static evaluation.
4057 if Ekind (Ent) = E_Enumeration_Literal then
4058 return Enumeration_Rep (Ent);
4060 -- A user defined static constant
4063 pragma Assert (Ekind (Ent) = E_Constant);
4064 return Expr_Rep_Value (Constant_Value (Ent));
4067 -- An integer literal that was either in the source or created as a
4068 -- result of static evaluation.
4070 elsif Kind = N_Integer_Literal then
4073 -- A real literal for a fixed-point type. This must be the fixed-point
4074 -- case, either the literal is of a fixed-point type, or it is a bound
4075 -- of a fixed-point type, with type universal real. In either case we
4076 -- obtain the desired value from Corresponding_Integer_Value.
4078 elsif Kind = N_Real_Literal then
4079 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
4080 return Corresponding_Integer_Value (N);
4082 -- Otherwise must be character literal
4085 pragma Assert (Kind = N_Character_Literal);
4088 -- Since Character literals of type Standard.Character don't have any
4089 -- defining character literals built for them, they do not have their
4090 -- Entity set, so just use their Char code. Otherwise for user-
4091 -- defined character literals use their Pos value as usual which is
4092 -- the same as the Rep value.
4095 return Char_Literal_Value (N);
4097 return Enumeration_Rep (Ent);
4106 function Expr_Value (N : Node_Id) return Uint is
4107 Kind : constant Node_Kind := Nkind (N);
4108 CV_Ent : CV_Entry renames CV_Cache (Nat (N) mod CV_Cache_Size);
4113 -- If already in cache, then we know it's compile time known and we can
4114 -- return the value that was previously stored in the cache since
4115 -- compile time known values cannot change.
4117 if CV_Ent.N = N then
4121 -- Otherwise proceed to test value
4123 if Is_Entity_Name (N) then
4126 -- An enumeration literal that was either in the source or created as
4127 -- a result of static evaluation.
4129 if Ekind (Ent) = E_Enumeration_Literal then
4130 Val := Enumeration_Pos (Ent);
4132 -- A user defined static constant
4135 pragma Assert (Ekind (Ent) = E_Constant);
4136 Val := Expr_Value (Constant_Value (Ent));
4139 -- An integer literal that was either in the source or created as a
4140 -- result of static evaluation.
4142 elsif Kind = N_Integer_Literal then
4145 -- A real literal for a fixed-point type. This must be the fixed-point
4146 -- case, either the literal is of a fixed-point type, or it is a bound
4147 -- of a fixed-point type, with type universal real. In either case we
4148 -- obtain the desired value from Corresponding_Integer_Value.
4150 elsif Kind = N_Real_Literal then
4151 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
4152 Val := Corresponding_Integer_Value (N);
4154 -- Otherwise must be character literal
4157 pragma Assert (Kind = N_Character_Literal);
4160 -- Since Character literals of type Standard.Character don't
4161 -- have any defining character literals built for them, they
4162 -- do not have their Entity set, so just use their Char
4163 -- code. Otherwise for user-defined character literals use
4164 -- their Pos value as usual.
4167 Val := Char_Literal_Value (N);
4169 Val := Enumeration_Pos (Ent);
4173 -- Come here with Val set to value to be returned, set cache
4184 function Expr_Value_E (N : Node_Id) return Entity_Id is
4185 Ent : constant Entity_Id := Entity (N);
4187 if Ekind (Ent) = E_Enumeration_Literal then
4190 pragma Assert (Ekind (Ent) = E_Constant);
4191 return Expr_Value_E (Constant_Value (Ent));
4199 function Expr_Value_R (N : Node_Id) return Ureal is
4200 Kind : constant Node_Kind := Nkind (N);
4204 if Kind = N_Real_Literal then
4207 elsif Kind = N_Identifier or else Kind = N_Expanded_Name then
4209 pragma Assert (Ekind (Ent) = E_Constant);
4210 return Expr_Value_R (Constant_Value (Ent));
4212 elsif Kind = N_Integer_Literal then
4213 return UR_From_Uint (Expr_Value (N));
4215 -- Here, we have a node that cannot be interpreted as a compile time
4216 -- constant. That is definitely an error.
4219 raise Program_Error;
4227 function Expr_Value_S (N : Node_Id) return Node_Id is
4229 if Nkind (N) = N_String_Literal then
4232 pragma Assert (Ekind (Entity (N)) = E_Constant);
4233 return Expr_Value_S (Constant_Value (Entity (N)));
4237 ----------------------------------
4238 -- Find_Universal_Operator_Type --
4239 ----------------------------------
4241 function Find_Universal_Operator_Type (N : Node_Id) return Entity_Id is
4242 PN : constant Node_Id := Parent (N);
4243 Call : constant Node_Id := Original_Node (N);
4244 Is_Int : constant Boolean := Is_Integer_Type (Etype (N));
4246 Is_Fix : constant Boolean :=
4247 Nkind (N) in N_Binary_Op
4248 and then Nkind (Right_Opnd (N)) /= Nkind (Left_Opnd (N));
4249 -- A mixed-mode operation in this context indicates the presence of
4250 -- fixed-point type in the designated package.
4252 Is_Relational : constant Boolean := Etype (N) = Standard_Boolean;
4253 -- Case where N is a relational (or membership) operator (else it is an
4256 In_Membership : constant Boolean :=
4257 Nkind (PN) in N_Membership_Test
4259 Nkind (Right_Opnd (PN)) = N_Range
4261 Is_Universal_Numeric_Type (Etype (Left_Opnd (PN)))
4263 Is_Universal_Numeric_Type
4264 (Etype (Low_Bound (Right_Opnd (PN))))
4266 Is_Universal_Numeric_Type
4267 (Etype (High_Bound (Right_Opnd (PN))));
4268 -- Case where N is part of a membership test with a universal range
4272 Typ1 : Entity_Id := Empty;
4275 function Is_Mixed_Mode_Operand (Op : Node_Id) return Boolean;
4276 -- Check whether one operand is a mixed-mode operation that requires the
4277 -- presence of a fixed-point type. Given that all operands are universal
4278 -- and have been constant-folded, retrieve the original function call.
4280 ---------------------------
4281 -- Is_Mixed_Mode_Operand --
4282 ---------------------------
4284 function Is_Mixed_Mode_Operand (Op : Node_Id) return Boolean is
4285 Onod : constant Node_Id := Original_Node (Op);
4287 return Nkind (Onod) = N_Function_Call
4288 and then Present (Next_Actual (First_Actual (Onod)))
4289 and then Etype (First_Actual (Onod)) /=
4290 Etype (Next_Actual (First_Actual (Onod)));
4291 end Is_Mixed_Mode_Operand;
4293 -- Start of processing for Find_Universal_Operator_Type
4296 if Nkind (Call) /= N_Function_Call
4297 or else Nkind (Name (Call)) /= N_Expanded_Name
4301 -- There are several cases where the context does not imply the type of
4303 -- - the universal expression appears in a type conversion;
4304 -- - the expression is a relational operator applied to universal
4306 -- - the expression is a membership test with a universal operand
4307 -- and a range with universal bounds.
4309 elsif Nkind (Parent (N)) = N_Type_Conversion
4310 or else Is_Relational
4311 or else In_Membership
4313 Pack := Entity (Prefix (Name (Call)));
4315 -- If the prefix is a package declared elsewhere, iterate over its
4316 -- visible entities, otherwise iterate over all declarations in the
4317 -- designated scope.
4319 if Ekind (Pack) = E_Package
4320 and then not In_Open_Scopes (Pack)
4322 Priv_E := First_Private_Entity (Pack);
4328 E := First_Entity (Pack);
4329 while Present (E) and then E /= Priv_E loop
4330 if Is_Numeric_Type (E)
4331 and then Nkind (Parent (E)) /= N_Subtype_Declaration
4332 and then Comes_From_Source (E)
4333 and then Is_Integer_Type (E) = Is_Int
4334 and then (Nkind (N) in N_Unary_Op
4335 or else Is_Relational
4336 or else Is_Fixed_Point_Type (E) = Is_Fix)
4341 -- Before emitting an error, check for the presence of a
4342 -- mixed-mode operation that specifies a fixed point type.
4346 (Is_Mixed_Mode_Operand (Left_Opnd (N))
4347 or else Is_Mixed_Mode_Operand (Right_Opnd (N)))
4348 and then Is_Fixed_Point_Type (E) /= Is_Fixed_Point_Type (Typ1)
4351 if Is_Fixed_Point_Type (E) then
4356 -- More than one type of the proper class declared in P
4358 Error_Msg_N ("ambiguous operation", N);
4359 Error_Msg_Sloc := Sloc (Typ1);
4360 Error_Msg_N ("\possible interpretation (inherited)#", N);
4361 Error_Msg_Sloc := Sloc (E);
4362 Error_Msg_N ("\possible interpretation (inherited)#", N);
4372 end Find_Universal_Operator_Type;
4374 --------------------------
4375 -- Flag_Non_Static_Expr --
4376 --------------------------
4378 procedure Flag_Non_Static_Expr (Msg : String; Expr : Node_Id) is
4380 if Error_Posted (Expr) and then not All_Errors_Mode then
4383 Error_Msg_F (Msg, Expr);
4384 Why_Not_Static (Expr);
4386 end Flag_Non_Static_Expr;
4392 procedure Fold_Str (N : Node_Id; Val : String_Id; Static : Boolean) is
4393 Loc : constant Source_Ptr := Sloc (N);
4394 Typ : constant Entity_Id := Etype (N);
4397 if Raises_Constraint_Error (N) then
4398 Set_Is_Static_Expression (N, Static);
4402 Rewrite (N, Make_String_Literal (Loc, Strval => Val));
4404 -- We now have the literal with the right value, both the actual type
4405 -- and the expected type of this literal are taken from the expression
4406 -- that was evaluated. So now we do the Analyze and Resolve.
4408 -- Note that we have to reset Is_Static_Expression both after the
4409 -- analyze step (because Resolve will evaluate the literal, which
4410 -- will cause semantic errors if it is marked as static), and after
4411 -- the Resolve step (since Resolve in some cases resets this flag).
4414 Set_Is_Static_Expression (N, Static);
4417 Set_Is_Static_Expression (N, Static);
4424 procedure Fold_Uint (N : Node_Id; Val : Uint; Static : Boolean) is
4425 Loc : constant Source_Ptr := Sloc (N);
4426 Typ : Entity_Id := Etype (N);
4430 if Raises_Constraint_Error (N) then
4431 Set_Is_Static_Expression (N, Static);
4435 -- If we are folding a named number, retain the entity in the literal,
4438 if Is_Entity_Name (N) and then Ekind (Entity (N)) = E_Named_Integer then
4444 if Is_Private_Type (Typ) then
4445 Typ := Full_View (Typ);
4448 -- For a result of type integer, substitute an N_Integer_Literal node
4449 -- for the result of the compile time evaluation of the expression.
4450 -- For ASIS use, set a link to the original named number when not in
4451 -- a generic context.
4453 if Is_Integer_Type (Typ) then
4454 Rewrite (N, Make_Integer_Literal (Loc, Val));
4455 Set_Original_Entity (N, Ent);
4457 -- Otherwise we have an enumeration type, and we substitute either
4458 -- an N_Identifier or N_Character_Literal to represent the enumeration
4459 -- literal corresponding to the given value, which must always be in
4460 -- range, because appropriate tests have already been made for this.
4462 else pragma Assert (Is_Enumeration_Type (Typ));
4463 Rewrite (N, Get_Enum_Lit_From_Pos (Etype (N), Val, Loc));
4466 -- We now have the literal with the right value, both the actual type
4467 -- and the expected type of this literal are taken from the expression
4468 -- that was evaluated. So now we do the Analyze and Resolve.
4470 -- Note that we have to reset Is_Static_Expression both after the
4471 -- analyze step (because Resolve will evaluate the literal, which
4472 -- will cause semantic errors if it is marked as static), and after
4473 -- the Resolve step (since Resolve in some cases sets this flag).
4476 Set_Is_Static_Expression (N, Static);
4479 Set_Is_Static_Expression (N, Static);
4486 procedure Fold_Ureal (N : Node_Id; Val : Ureal; Static : Boolean) is
4487 Loc : constant Source_Ptr := Sloc (N);
4488 Typ : constant Entity_Id := Etype (N);
4492 if Raises_Constraint_Error (N) then
4493 Set_Is_Static_Expression (N, Static);
4497 -- If we are folding a named number, retain the entity in the literal,
4500 if Is_Entity_Name (N) and then Ekind (Entity (N)) = E_Named_Real then
4506 Rewrite (N, Make_Real_Literal (Loc, Realval => Val));
4508 -- Set link to original named number, for ASIS use
4510 Set_Original_Entity (N, Ent);
4512 -- We now have the literal with the right value, both the actual type
4513 -- and the expected type of this literal are taken from the expression
4514 -- that was evaluated. So now we do the Analyze and Resolve.
4516 -- Note that we have to reset Is_Static_Expression both after the
4517 -- analyze step (because Resolve will evaluate the literal, which
4518 -- will cause semantic errors if it is marked as static), and after
4519 -- the Resolve step (since Resolve in some cases sets this flag).
4522 Set_Is_Static_Expression (N, Static);
4525 Set_Is_Static_Expression (N, Static);
4532 function From_Bits (B : Bits; T : Entity_Id) return Uint is
4536 for J in 0 .. B'Last loop
4542 if Non_Binary_Modulus (T) then
4543 V := V mod Modulus (T);
4549 --------------------
4550 -- Get_String_Val --
4551 --------------------
4553 function Get_String_Val (N : Node_Id) return Node_Id is
4555 if Nkind_In (N, N_String_Literal, N_Character_Literal) then
4558 pragma Assert (Is_Entity_Name (N));
4559 return Get_String_Val (Constant_Value (Entity (N)));
4567 procedure Initialize is
4569 CV_Cache := (others => (Node_High_Bound, Uint_0));
4572 --------------------
4573 -- In_Subrange_Of --
4574 --------------------
4576 function In_Subrange_Of
4579 Fixed_Int : Boolean := False) return Boolean
4588 if T1 = T2 or else Is_Subtype_Of (T1, T2) then
4591 -- Never in range if both types are not scalar. Don't know if this can
4592 -- actually happen, but just in case.
4594 elsif not Is_Scalar_Type (T1) or else not Is_Scalar_Type (T2) then
4597 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
4598 -- definitely not compatible with T2.
4600 elsif Is_Floating_Point_Type (T1)
4601 and then Has_Infinities (T1)
4602 and then Is_Floating_Point_Type (T2)
4603 and then not Has_Infinities (T2)
4608 L1 := Type_Low_Bound (T1);
4609 H1 := Type_High_Bound (T1);
4611 L2 := Type_Low_Bound (T2);
4612 H2 := Type_High_Bound (T2);
4614 -- Check bounds to see if comparison possible at compile time
4616 if Compile_Time_Compare (L1, L2, Assume_Valid => True) in Compare_GE
4618 Compile_Time_Compare (H1, H2, Assume_Valid => True) in Compare_LE
4623 -- If bounds not comparable at compile time, then the bounds of T2
4624 -- must be compile time known or we cannot answer the query.
4626 if not Compile_Time_Known_Value (L2)
4627 or else not Compile_Time_Known_Value (H2)
4632 -- If the bounds of T1 are know at compile time then use these
4633 -- ones, otherwise use the bounds of the base type (which are of
4634 -- course always static).
4636 if not Compile_Time_Known_Value (L1) then
4637 L1 := Type_Low_Bound (Base_Type (T1));
4640 if not Compile_Time_Known_Value (H1) then
4641 H1 := Type_High_Bound (Base_Type (T1));
4644 -- Fixed point types should be considered as such only if
4645 -- flag Fixed_Int is set to False.
4647 if Is_Floating_Point_Type (T1) or else Is_Floating_Point_Type (T2)
4648 or else (Is_Fixed_Point_Type (T1) and then not Fixed_Int)
4649 or else (Is_Fixed_Point_Type (T2) and then not Fixed_Int)
4652 Expr_Value_R (L2) <= Expr_Value_R (L1)
4654 Expr_Value_R (H2) >= Expr_Value_R (H1);
4658 Expr_Value (L2) <= Expr_Value (L1)
4660 Expr_Value (H2) >= Expr_Value (H1);
4665 -- If any exception occurs, it means that we have some bug in the compiler
4666 -- possibly triggered by a previous error, or by some unforeseen peculiar
4667 -- occurrence. However, this is only an optimization attempt, so there is
4668 -- really no point in crashing the compiler. Instead we just decide, too
4669 -- bad, we can't figure out the answer in this case after all.
4674 -- Debug flag K disables this behavior (useful for debugging)
4676 if Debug_Flag_K then
4687 function Is_In_Range
4690 Assume_Valid : Boolean := False;
4691 Fixed_Int : Boolean := False;
4692 Int_Real : Boolean := False) return Boolean
4696 Test_In_Range (N, Typ, Assume_Valid, Fixed_Int, Int_Real) = In_Range;
4703 function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
4704 Typ : constant Entity_Id := Etype (Lo);
4707 if not Compile_Time_Known_Value (Lo)
4708 or else not Compile_Time_Known_Value (Hi)
4713 if Is_Discrete_Type (Typ) then
4714 return Expr_Value (Lo) > Expr_Value (Hi);
4715 else pragma Assert (Is_Real_Type (Typ));
4716 return Expr_Value_R (Lo) > Expr_Value_R (Hi);
4720 -------------------------
4721 -- Is_OK_Static_Choice --
4722 -------------------------
4724 function Is_OK_Static_Choice (Choice : Node_Id) return Boolean is
4726 -- Check various possibilities for choice
4728 -- Note: for membership tests, we test more cases than are possible
4729 -- (in particular subtype indication), but it doesn't matter because
4730 -- it just won't occur (we have already done a syntax check).
4732 if Nkind (Choice) = N_Others_Choice then
4735 elsif Nkind (Choice) = N_Range then
4736 return Is_OK_Static_Range (Choice);
4738 elsif Nkind (Choice) = N_Subtype_Indication
4739 or else (Is_Entity_Name (Choice) and then Is_Type (Entity (Choice)))
4741 return Is_OK_Static_Subtype (Etype (Choice));
4744 return Is_OK_Static_Expression (Choice);
4746 end Is_OK_Static_Choice;
4748 ------------------------------
4749 -- Is_OK_Static_Choice_List --
4750 ------------------------------
4752 function Is_OK_Static_Choice_List (Choices : List_Id) return Boolean is
4756 if not Is_Static_Choice_List (Choices) then
4760 Choice := First (Choices);
4761 while Present (Choice) loop
4762 if not Is_OK_Static_Choice (Choice) then
4763 Set_Raises_Constraint_Error (Choice);
4771 end Is_OK_Static_Choice_List;
4773 -----------------------------
4774 -- Is_OK_Static_Expression --
4775 -----------------------------
4777 function Is_OK_Static_Expression (N : Node_Id) return Boolean is
4779 return Is_Static_Expression (N) and then not Raises_Constraint_Error (N);
4780 end Is_OK_Static_Expression;
4782 ------------------------
4783 -- Is_OK_Static_Range --
4784 ------------------------
4786 -- A static range is a range whose bounds are static expressions, or a
4787 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4788 -- We have already converted range attribute references, so we get the
4789 -- "or" part of this rule without needing a special test.
4791 function Is_OK_Static_Range (N : Node_Id) return Boolean is
4793 return Is_OK_Static_Expression (Low_Bound (N))
4794 and then Is_OK_Static_Expression (High_Bound (N));
4795 end Is_OK_Static_Range;
4797 --------------------------
4798 -- Is_OK_Static_Subtype --
4799 --------------------------
4801 -- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
4802 -- neither bound raises constraint error when evaluated.
4804 function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean is
4805 Base_T : constant Entity_Id := Base_Type (Typ);
4806 Anc_Subt : Entity_Id;
4809 -- First a quick check on the non static subtype flag. As described
4810 -- in further detail in Einfo, this flag is not decisive in all cases,
4811 -- but if it is set, then the subtype is definitely non-static.
4813 if Is_Non_Static_Subtype (Typ) then
4817 Anc_Subt := Ancestor_Subtype (Typ);
4819 if Anc_Subt = Empty then
4823 if Is_Generic_Type (Root_Type (Base_T))
4824 or else Is_Generic_Actual_Type (Base_T)
4828 elsif Has_Dynamic_Predicate_Aspect (Typ) then
4833 elsif Is_String_Type (Typ) then
4835 Ekind (Typ) = E_String_Literal_Subtype
4837 (Is_OK_Static_Subtype (Component_Type (Typ))
4838 and then Is_OK_Static_Subtype (Etype (First_Index (Typ))));
4842 elsif Is_Scalar_Type (Typ) then
4843 if Base_T = Typ then
4847 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
4848 -- Get_Type_{Low,High}_Bound.
4850 return Is_OK_Static_Subtype (Anc_Subt)
4851 and then Is_OK_Static_Expression (Type_Low_Bound (Typ))
4852 and then Is_OK_Static_Expression (Type_High_Bound (Typ));
4855 -- Types other than string and scalar types are never static
4860 end Is_OK_Static_Subtype;
4862 ---------------------
4863 -- Is_Out_Of_Range --
4864 ---------------------
4866 function Is_Out_Of_Range
4869 Assume_Valid : Boolean := False;
4870 Fixed_Int : Boolean := False;
4871 Int_Real : Boolean := False) return Boolean
4874 return Test_In_Range (N, Typ, Assume_Valid, Fixed_Int, Int_Real) =
4876 end Is_Out_Of_Range;
4878 ----------------------
4879 -- Is_Static_Choice --
4880 ----------------------
4882 function Is_Static_Choice (Choice : Node_Id) return Boolean is
4884 -- Check various possibilities for choice
4886 -- Note: for membership tests, we test more cases than are possible
4887 -- (in particular subtype indication), but it doesn't matter because
4888 -- it just won't occur (we have already done a syntax check).
4890 if Nkind (Choice) = N_Others_Choice then
4893 elsif Nkind (Choice) = N_Range then
4894 return Is_Static_Range (Choice);
4896 elsif Nkind (Choice) = N_Subtype_Indication
4897 or else (Is_Entity_Name (Choice) and then Is_Type (Entity (Choice)))
4899 return Is_Static_Subtype (Etype (Choice));
4902 return Is_Static_Expression (Choice);
4904 end Is_Static_Choice;
4906 ---------------------------
4907 -- Is_Static_Choice_List --
4908 ---------------------------
4910 function Is_Static_Choice_List (Choices : List_Id) return Boolean is
4914 Choice := First (Choices);
4915 while Present (Choice) loop
4916 if not Is_Static_Choice (Choice) then
4924 end Is_Static_Choice_List;
4926 ---------------------
4927 -- Is_Static_Range --
4928 ---------------------
4930 -- A static range is a range whose bounds are static expressions, or a
4931 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4932 -- We have already converted range attribute references, so we get the
4933 -- "or" part of this rule without needing a special test.
4935 function Is_Static_Range (N : Node_Id) return Boolean is
4937 return Is_Static_Expression (Low_Bound (N))
4939 Is_Static_Expression (High_Bound (N));
4940 end Is_Static_Range;
4942 -----------------------
4943 -- Is_Static_Subtype --
4944 -----------------------
4946 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
4948 function Is_Static_Subtype (Typ : Entity_Id) return Boolean is
4949 Base_T : constant Entity_Id := Base_Type (Typ);
4950 Anc_Subt : Entity_Id;
4953 -- First a quick check on the non static subtype flag. As described
4954 -- in further detail in Einfo, this flag is not decisive in all cases,
4955 -- but if it is set, then the subtype is definitely non-static.
4957 if Is_Non_Static_Subtype (Typ) then
4961 Anc_Subt := Ancestor_Subtype (Typ);
4963 if Anc_Subt = Empty then
4967 if Is_Generic_Type (Root_Type (Base_T))
4968 or else Is_Generic_Actual_Type (Base_T)
4972 elsif Has_Dynamic_Predicate_Aspect (Typ) then
4977 elsif Is_String_Type (Typ) then
4979 Ekind (Typ) = E_String_Literal_Subtype
4980 or else (Is_Static_Subtype (Component_Type (Typ))
4981 and then Is_Static_Subtype (Etype (First_Index (Typ))));
4985 elsif Is_Scalar_Type (Typ) then
4986 if Base_T = Typ then
4990 return Is_Static_Subtype (Anc_Subt)
4991 and then Is_Static_Expression (Type_Low_Bound (Typ))
4992 and then Is_Static_Expression (Type_High_Bound (Typ));
4995 -- Types other than string and scalar types are never static
5000 end Is_Static_Subtype;
5002 -------------------------------
5003 -- Is_Statically_Unevaluated --
5004 -------------------------------
5006 function Is_Statically_Unevaluated (Expr : Node_Id) return Boolean is
5007 function Check_Case_Expr_Alternative
5008 (CEA : Node_Id) return Match_Result;
5009 -- We have a message emanating from the Expression of a case expression
5010 -- alternative. We examine this alternative, as follows:
5012 -- If the selecting expression of the parent case is non-static, or
5013 -- if any of the discrete choices of the given case alternative are
5014 -- non-static or raise Constraint_Error, return Non_Static.
5016 -- Otherwise check if the selecting expression matches any of the given
5017 -- discrete choices. If so, the alternative is executed and we return
5018 -- Match, otherwise, the alternative can never be executed, and so we
5021 ---------------------------------
5022 -- Check_Case_Expr_Alternative --
5023 ---------------------------------
5025 function Check_Case_Expr_Alternative
5026 (CEA : Node_Id) return Match_Result
5028 Case_Exp : constant Node_Id := Parent (CEA);
5033 pragma Assert (Nkind (Case_Exp) = N_Case_Expression);
5035 -- Check that selecting expression is static
5037 if not Is_OK_Static_Expression (Expression (Case_Exp)) then
5041 if not Is_OK_Static_Choice_List (Discrete_Choices (CEA)) then
5045 -- All choices are now known to be static. Now see if alternative
5046 -- matches one of the choices.
5048 Choice := First (Discrete_Choices (CEA));
5049 while Present (Choice) loop
5051 -- Check various possibilities for choice, returning Match if we
5052 -- find the selecting value matches any of the choices. Note that
5053 -- we know we are the last choice, so we don't have to keep going.
5055 if Nkind (Choice) = N_Others_Choice then
5057 -- Others choice is a bit annoying, it matches if none of the
5058 -- previous alternatives matches (note that we know we are the
5059 -- last alternative in this case, so we can just go backwards
5060 -- from us to see if any previous one matches).
5062 Prev_CEA := Prev (CEA);
5063 while Present (Prev_CEA) loop
5064 if Check_Case_Expr_Alternative (Prev_CEA) = Match then
5073 -- Else we have a normal static choice
5075 elsif Choice_Matches (Expression (Case_Exp), Choice) = Match then
5079 -- If we fall through, it means that the discrete choice did not
5080 -- match the selecting expression, so continue.
5085 -- If we get through that loop then all choices were static, and none
5086 -- of them matched the selecting expression. So return No_Match.
5089 end Check_Case_Expr_Alternative;
5097 -- Start of processing for Is_Statically_Unevaluated
5100 -- The (32.x) references here are from RM section 4.9
5102 -- (32.1) An expression is statically unevaluated if it is part of ...
5104 -- This means we have to climb the tree looking for one of the cases
5111 -- (32.2) The right operand of a static short-circuit control form
5112 -- whose value is determined by its left operand.
5114 -- AND THEN with False as left operand
5116 if Nkind (P) = N_And_Then
5117 and then Compile_Time_Known_Value (Left_Opnd (P))
5118 and then Is_False (Expr_Value (Left_Opnd (P)))
5122 -- OR ELSE with True as left operand
5124 elsif Nkind (P) = N_Or_Else
5125 and then Compile_Time_Known_Value (Left_Opnd (P))
5126 and then Is_True (Expr_Value (Left_Opnd (P)))
5130 -- (32.3) A dependent_expression of an if_expression whose associated
5131 -- condition is static and equals False.
5133 elsif Nkind (P) = N_If_Expression then
5135 Cond : constant Node_Id := First (Expressions (P));
5136 Texp : constant Node_Id := Next (Cond);
5137 Fexp : constant Node_Id := Next (Texp);
5140 if Compile_Time_Known_Value (Cond) then
5142 -- Condition is True and we are in the right operand
5144 if Is_True (Expr_Value (Cond)) and then OldP = Fexp then
5147 -- Condition is False and we are in the left operand
5149 elsif Is_False (Expr_Value (Cond)) and then OldP = Texp then
5155 -- (32.4) A condition or dependent_expression of an if_expression
5156 -- where the condition corresponding to at least one preceding
5157 -- dependent_expression of the if_expression is static and equals
5160 -- This refers to cases like
5162 -- (if True then 1 elsif 1/0=2 then 2 else 3)
5164 -- But we expand elsif's out anyway, so the above looks like:
5166 -- (if True then 1 else (if 1/0=2 then 2 else 3))
5168 -- So for us this is caught by the above check for the 32.3 case.
5170 -- (32.5) A dependent_expression of a case_expression whose
5171 -- selecting_expression is static and whose value is not covered
5172 -- by the corresponding discrete_choice_list.
5174 elsif Nkind (P) = N_Case_Expression_Alternative then
5176 -- First, we have to be in the expression to suppress messages.
5177 -- If we are within one of the choices, we want the message.
5179 if OldP = Expression (P) then
5181 -- Statically unevaluated if alternative does not match
5183 if Check_Case_Expr_Alternative (P) = No_Match then
5188 -- (32.6) A choice_expression (or a simple_expression of a range
5189 -- that occurs as a membership_choice of a membership_choice_list)
5190 -- of a static membership test that is preceded in the enclosing
5191 -- membership_choice_list by another item whose individual
5192 -- membership test (see (RM 4.5.2)) statically yields True.
5194 elsif Nkind (P) in N_Membership_Test then
5196 -- Only possibly unevaluated if simple expression is static
5198 if not Is_OK_Static_Expression (Left_Opnd (P)) then
5201 -- All members of the choice list must be static
5203 elsif (Present (Right_Opnd (P))
5204 and then not Is_OK_Static_Choice (Right_Opnd (P)))
5205 or else (Present (Alternatives (P))
5207 not Is_OK_Static_Choice_List (Alternatives (P)))
5211 -- If expression is the one and only alternative, then it is
5212 -- definitely not statically unevaluated, so we only have to
5213 -- test the case where there are alternatives present.
5215 elsif Present (Alternatives (P)) then
5217 -- Look for previous matching Choice
5219 Choice := First (Alternatives (P));
5220 while Present (Choice) loop
5222 -- If we reached us and no previous choices matched, this
5223 -- is not the case where we are statically unevaluated.
5225 exit when OldP = Choice;
5227 -- If a previous choice matches, then that is the case where
5228 -- we know our choice is statically unevaluated.
5230 if Choice_Matches (Left_Opnd (P), Choice) = Match then
5237 -- If we fall through the loop, we were not one of the choices,
5238 -- we must have been the expression, so that is not covered by
5239 -- this rule, and we keep going.
5245 -- OK, not statically unevaluated at this level, see if we should
5246 -- keep climbing to look for a higher level reason.
5248 -- Special case for component association in aggregates, where
5249 -- we want to keep climbing up to the parent aggregate.
5251 if Nkind (P) = N_Component_Association
5252 and then Nkind (Parent (P)) = N_Aggregate
5256 -- All done if not still within subexpression
5259 exit when Nkind (P) not in N_Subexpr;
5263 -- If we fall through the loop, not one of the cases covered!
5266 end Is_Statically_Unevaluated;
5268 --------------------
5269 -- Not_Null_Range --
5270 --------------------
5272 function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
5273 Typ : constant Entity_Id := Etype (Lo);
5276 if not Compile_Time_Known_Value (Lo)
5277 or else not Compile_Time_Known_Value (Hi)
5282 if Is_Discrete_Type (Typ) then
5283 return Expr_Value (Lo) <= Expr_Value (Hi);
5284 else pragma Assert (Is_Real_Type (Typ));
5285 return Expr_Value_R (Lo) <= Expr_Value_R (Hi);
5293 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean is
5295 -- We allow a maximum of 500,000 bits which seems a reasonable limit
5297 if Bits < 500_000 then
5300 -- Error if this maximum is exceeded
5303 Error_Msg_N ("static value too large, capacity exceeded", N);
5312 procedure Out_Of_Range (N : Node_Id) is
5314 -- If we have the static expression case, then this is an illegality
5315 -- in Ada 95 mode, except that in an instance, we never generate an
5316 -- error (if the error is legitimate, it was already diagnosed in the
5319 if Is_Static_Expression (N)
5320 and then not In_Instance
5321 and then not In_Inlined_Body
5322 and then Ada_Version >= Ada_95
5324 -- No message if we are statically unevaluated
5326 if Is_Statically_Unevaluated (N) then
5329 -- The expression to compute the length of a packed array is attached
5330 -- to the array type itself, and deserves a separate message.
5332 elsif Nkind (Parent (N)) = N_Defining_Identifier
5333 and then Is_Array_Type (Parent (N))
5334 and then Present (Packed_Array_Impl_Type (Parent (N)))
5335 and then Present (First_Rep_Item (Parent (N)))
5338 ("length of packed array must not exceed Integer''Last",
5339 First_Rep_Item (Parent (N)));
5340 Rewrite (N, Make_Integer_Literal (Sloc (N), Uint_1));
5342 -- All cases except the special array case
5345 Apply_Compile_Time_Constraint_Error
5346 (N, "value not in range of}", CE_Range_Check_Failed);
5349 -- Here we generate a warning for the Ada 83 case, or when we are in an
5350 -- instance, or when we have a non-static expression case.
5353 Apply_Compile_Time_Constraint_Error
5354 (N, "value not in range of}??", CE_Range_Check_Failed);
5358 ----------------------
5359 -- Predicates_Match --
5360 ----------------------
5362 function Predicates_Match (T1, T2 : Entity_Id) return Boolean is
5367 if Ada_Version < Ada_2012 then
5370 -- Both types must have predicates or lack them
5372 elsif Has_Predicates (T1) /= Has_Predicates (T2) then
5375 -- Check matching predicates
5380 (T1, Name_Static_Predicate, Check_Parents => False);
5383 (T2, Name_Static_Predicate, Check_Parents => False);
5385 -- Subtypes statically match if the predicate comes from the
5386 -- same declaration, which can only happen if one is a subtype
5387 -- of the other and has no explicit predicate.
5389 -- Suppress warnings on order of actuals, which is otherwise
5390 -- triggered by one of the two calls below.
5392 pragma Warnings (Off);
5393 return Pred1 = Pred2
5394 or else (No (Pred1) and then Is_Subtype_Of (T1, T2))
5395 or else (No (Pred2) and then Is_Subtype_Of (T2, T1));
5396 pragma Warnings (On);
5398 end Predicates_Match;
5400 ---------------------------------------------
5401 -- Real_Or_String_Static_Predicate_Matches --
5402 ---------------------------------------------
5404 function Real_Or_String_Static_Predicate_Matches
5406 Typ : Entity_Id) return Boolean
5408 Expr : constant Node_Id := Static_Real_Or_String_Predicate (Typ);
5409 -- The predicate expression from the type
5411 Pfun : constant Entity_Id := Predicate_Function (Typ);
5412 -- The entity for the predicate function
5414 Ent_Name : constant Name_Id := Chars (First_Formal (Pfun));
5415 -- The name of the formal of the predicate function. Occurrences of the
5416 -- type name in Expr have been rewritten as references to this formal,
5417 -- and it has a unique name, so we can identify references by this name.
5420 -- Copy of the predicate function tree
5422 function Process (N : Node_Id) return Traverse_Result;
5423 -- Function used to process nodes during the traversal in which we will
5424 -- find occurrences of the entity name, and replace such occurrences
5425 -- by a real literal with the value to be tested.
5427 procedure Traverse is new Traverse_Proc (Process);
5428 -- The actual traversal procedure
5434 function Process (N : Node_Id) return Traverse_Result is
5436 if Nkind (N) = N_Identifier and then Chars (N) = Ent_Name then
5438 Nod : constant Node_Id := New_Copy (Val);
5440 Set_Sloc (Nod, Sloc (N));
5450 -- Start of processing for Real_Or_String_Static_Predicate_Matches
5453 -- First deal with special case of inherited predicate, where the
5454 -- predicate expression looks like:
5456 -- xxPredicate (typ (Ent)) and then Expr
5458 -- where Expr is the predicate expression for this level, and the
5459 -- left operand is the call to evaluate the inherited predicate.
5461 if Nkind (Expr) = N_And_Then
5462 and then Nkind (Left_Opnd (Expr)) = N_Function_Call
5463 and then Is_Predicate_Function (Entity (Name (Left_Opnd (Expr))))
5465 -- OK we have the inherited case, so make a call to evaluate the
5466 -- inherited predicate. If that fails, so do we!
5469 Real_Or_String_Static_Predicate_Matches
5471 Typ => Etype (First_Formal (Entity (Name (Left_Opnd (Expr))))))
5476 -- Use the right operand for the continued processing
5478 Copy := Copy_Separate_Tree (Right_Opnd (Expr));
5480 -- Case where call to predicate function appears on its own (this means
5481 -- that the predicate at this level is just inherited from the parent).
5483 elsif Nkind (Expr) = N_Function_Call then
5485 Typ : constant Entity_Id :=
5486 Etype (First_Formal (Entity (Name (Expr))));
5489 -- If the inherited predicate is dynamic, just ignore it. We can't
5490 -- go trying to evaluate a dynamic predicate as a static one!
5492 if Has_Dynamic_Predicate_Aspect (Typ) then
5495 -- Otherwise inherited predicate is static, check for match
5498 return Real_Or_String_Static_Predicate_Matches (Val, Typ);
5502 -- If not just an inherited predicate, copy whole expression
5505 Copy := Copy_Separate_Tree (Expr);
5508 -- Now we replace occurrences of the entity by the value
5512 -- And analyze the resulting static expression to see if it is True
5514 Analyze_And_Resolve (Copy, Standard_Boolean);
5515 return Is_True (Expr_Value (Copy));
5516 end Real_Or_String_Static_Predicate_Matches;
5518 -------------------------
5519 -- Rewrite_In_Raise_CE --
5520 -------------------------
5522 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id) is
5523 Typ : constant Entity_Id := Etype (N);
5524 Stat : constant Boolean := Is_Static_Expression (N);
5527 -- If we want to raise CE in the condition of a N_Raise_CE node, we
5528 -- can just clear the condition if the reason is appropriate. We do
5529 -- not do this operation if the parent has a reason other than range
5530 -- check failed, because otherwise we would change the reason.
5532 if Present (Parent (N))
5533 and then Nkind (Parent (N)) = N_Raise_Constraint_Error
5534 and then Reason (Parent (N)) =
5535 UI_From_Int (RT_Exception_Code'Pos (CE_Range_Check_Failed))
5537 Set_Condition (Parent (N), Empty);
5539 -- Else build an explicit N_Raise_CE
5543 Make_Raise_Constraint_Error (Sloc (Exp),
5544 Reason => CE_Range_Check_Failed));
5545 Set_Raises_Constraint_Error (N);
5549 -- Set proper flags in result
5551 Set_Raises_Constraint_Error (N, True);
5552 Set_Is_Static_Expression (N, Stat);
5553 end Rewrite_In_Raise_CE;
5555 ---------------------
5556 -- String_Type_Len --
5557 ---------------------
5559 function String_Type_Len (Stype : Entity_Id) return Uint is
5560 NT : constant Entity_Id := Etype (First_Index (Stype));
5564 if Is_OK_Static_Subtype (NT) then
5567 T := Base_Type (NT);
5570 return Expr_Value (Type_High_Bound (T)) -
5571 Expr_Value (Type_Low_Bound (T)) + 1;
5572 end String_Type_Len;
5574 ------------------------------------
5575 -- Subtypes_Statically_Compatible --
5576 ------------------------------------
5578 function Subtypes_Statically_Compatible
5581 Formal_Derived_Matching : Boolean := False) return Boolean
5586 if Is_Scalar_Type (T1) then
5588 -- Definitely compatible if we match
5590 if Subtypes_Statically_Match (T1, T2) then
5593 -- If either subtype is nonstatic then they're not compatible
5595 elsif not Is_OK_Static_Subtype (T1)
5597 not Is_OK_Static_Subtype (T2)
5601 -- If either type has constraint error bounds, then consider that
5602 -- they match to avoid junk cascaded errors here.
5604 elsif not Is_OK_Static_Subtype (T1)
5605 or else not Is_OK_Static_Subtype (T2)
5609 -- Base types must match, but we don't check that (should we???) but
5610 -- we do at least check that both types are real, or both types are
5613 elsif Is_Real_Type (T1) /= Is_Real_Type (T2) then
5616 -- Here we check the bounds
5620 LB1 : constant Node_Id := Type_Low_Bound (T1);
5621 HB1 : constant Node_Id := Type_High_Bound (T1);
5622 LB2 : constant Node_Id := Type_Low_Bound (T2);
5623 HB2 : constant Node_Id := Type_High_Bound (T2);
5626 if Is_Real_Type (T1) then
5628 (Expr_Value_R (LB1) > Expr_Value_R (HB1))
5630 (Expr_Value_R (LB2) <= Expr_Value_R (LB1)
5632 Expr_Value_R (HB1) <= Expr_Value_R (HB2));
5636 (Expr_Value (LB1) > Expr_Value (HB1))
5638 (Expr_Value (LB2) <= Expr_Value (LB1)
5640 Expr_Value (HB1) <= Expr_Value (HB2));
5647 elsif Is_Access_Type (T1) then
5648 return (not Is_Constrained (T2)
5649 or else (Subtypes_Statically_Match
5650 (Designated_Type (T1), Designated_Type (T2))))
5651 and then not (Can_Never_Be_Null (T2)
5652 and then not Can_Never_Be_Null (T1));
5657 return (Is_Composite_Type (T1) and then not Is_Constrained (T2))
5658 or else Subtypes_Statically_Match (T1, T2, Formal_Derived_Matching);
5660 end Subtypes_Statically_Compatible;
5662 -------------------------------
5663 -- Subtypes_Statically_Match --
5664 -------------------------------
5666 -- Subtypes statically match if they have statically matching constraints
5667 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
5668 -- they are the same identical constraint, or if they are static and the
5669 -- values match (RM 4.9.1(1)).
5671 -- In addition, in GNAT, the object size (Esize) values of the types must
5672 -- match if they are set (unless checking an actual for a formal derived
5673 -- type). The use of 'Object_Size can cause this to be false even if the
5674 -- types would otherwise match in the RM sense.
5676 function Subtypes_Statically_Match
5679 Formal_Derived_Matching : Boolean := False) return Boolean
5682 -- A type always statically matches itself
5687 -- No match if sizes different (from use of 'Object_Size). This test
5688 -- is excluded if Formal_Derived_Matching is True, as the base types
5689 -- can be different in that case and typically have different sizes
5690 -- (and Esizes can be set when Frontend_Layout_On_Target is True).
5692 elsif not Formal_Derived_Matching
5693 and then Known_Static_Esize (T1)
5694 and then Known_Static_Esize (T2)
5695 and then Esize (T1) /= Esize (T2)
5699 -- No match if predicates do not match
5701 elsif not Predicates_Match (T1, T2) then
5706 elsif Is_Scalar_Type (T1) then
5708 -- Base types must be the same
5710 if Base_Type (T1) /= Base_Type (T2) then
5714 -- A constrained numeric subtype never matches an unconstrained
5715 -- subtype, i.e. both types must be constrained or unconstrained.
5717 -- To understand the requirement for this test, see RM 4.9.1(1).
5718 -- As is made clear in RM 3.5.4(11), type Integer, for example is
5719 -- a constrained subtype with constraint bounds matching the bounds
5720 -- of its corresponding unconstrained base type. In this situation,
5721 -- Integer and Integer'Base do not statically match, even though
5722 -- they have the same bounds.
5724 -- We only apply this test to types in Standard and types that appear
5725 -- in user programs. That way, we do not have to be too careful about
5726 -- setting Is_Constrained right for Itypes.
5728 if Is_Numeric_Type (T1)
5729 and then (Is_Constrained (T1) /= Is_Constrained (T2))
5730 and then (Scope (T1) = Standard_Standard
5731 or else Comes_From_Source (T1))
5732 and then (Scope (T2) = Standard_Standard
5733 or else Comes_From_Source (T2))
5737 -- A generic scalar type does not statically match its base type
5738 -- (AI-311). In this case we make sure that the formals, which are
5739 -- first subtypes of their bases, are constrained.
5741 elsif Is_Generic_Type (T1)
5742 and then Is_Generic_Type (T2)
5743 and then (Is_Constrained (T1) /= Is_Constrained (T2))
5748 -- If there was an error in either range, then just assume the types
5749 -- statically match to avoid further junk errors.
5751 if No (Scalar_Range (T1)) or else No (Scalar_Range (T2))
5752 or else Error_Posted (Scalar_Range (T1))
5753 or else Error_Posted (Scalar_Range (T2))
5758 -- Otherwise both types have bounds that can be compared
5761 LB1 : constant Node_Id := Type_Low_Bound (T1);
5762 HB1 : constant Node_Id := Type_High_Bound (T1);
5763 LB2 : constant Node_Id := Type_Low_Bound (T2);
5764 HB2 : constant Node_Id := Type_High_Bound (T2);
5767 -- If the bounds are the same tree node, then match (common case)
5769 if LB1 = LB2 and then HB1 = HB2 then
5772 -- Otherwise bounds must be static and identical value
5775 if not Is_OK_Static_Subtype (T1)
5776 or else not Is_OK_Static_Subtype (T2)
5780 -- If either type has constraint error bounds, then say that
5781 -- they match to avoid junk cascaded errors here.
5783 elsif not Is_OK_Static_Subtype (T1)
5784 or else not Is_OK_Static_Subtype (T2)
5788 elsif Is_Real_Type (T1) then
5790 (Expr_Value_R (LB1) = Expr_Value_R (LB2))
5792 (Expr_Value_R (HB1) = Expr_Value_R (HB2));
5796 Expr_Value (LB1) = Expr_Value (LB2)
5798 Expr_Value (HB1) = Expr_Value (HB2);
5803 -- Type with discriminants
5805 elsif Has_Discriminants (T1) or else Has_Discriminants (T2) then
5807 -- Because of view exchanges in multiple instantiations, conformance
5808 -- checking might try to match a partial view of a type with no
5809 -- discriminants with a full view that has defaulted discriminants.
5810 -- In such a case, use the discriminant constraint of the full view,
5811 -- which must exist because we know that the two subtypes have the
5814 if Has_Discriminants (T1) /= Has_Discriminants (T2) then
5815 -- A generic actual type is declared through a subtype declaration
5816 -- and may have an inconsistent indication of the presence of
5817 -- discriminants, so check the type it renames.
5819 if Is_Generic_Actual_Type (T1)
5820 and then not Has_Discriminants (Etype (T1))
5821 and then not Has_Discriminants (T2)
5825 elsif In_Instance then
5826 if Is_Private_Type (T2)
5827 and then Present (Full_View (T2))
5828 and then Has_Discriminants (Full_View (T2))
5830 return Subtypes_Statically_Match (T1, Full_View (T2));
5832 elsif Is_Private_Type (T1)
5833 and then Present (Full_View (T1))
5834 and then Has_Discriminants (Full_View (T1))
5836 return Subtypes_Statically_Match (Full_View (T1), T2);
5847 DL1 : constant Elist_Id := Discriminant_Constraint (T1);
5848 DL2 : constant Elist_Id := Discriminant_Constraint (T2);
5856 elsif Is_Constrained (T1) /= Is_Constrained (T2) then
5860 -- Now loop through the discriminant constraints
5862 -- Note: the guard here seems necessary, since it is possible at
5863 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
5865 if Present (DL1) and then Present (DL2) then
5866 DA1 := First_Elmt (DL1);
5867 DA2 := First_Elmt (DL2);
5868 while Present (DA1) loop
5870 Expr1 : constant Node_Id := Node (DA1);
5871 Expr2 : constant Node_Id := Node (DA2);
5874 if not Is_OK_Static_Expression (Expr1)
5875 or else not Is_OK_Static_Expression (Expr2)
5879 -- If either expression raised a constraint error,
5880 -- consider the expressions as matching, since this
5881 -- helps to prevent cascading errors.
5883 elsif Raises_Constraint_Error (Expr1)
5884 or else Raises_Constraint_Error (Expr2)
5888 elsif Expr_Value (Expr1) /= Expr_Value (Expr2) then
5901 -- A definite type does not match an indefinite or classwide type.
5902 -- However, a generic type with unknown discriminants may be
5903 -- instantiated with a type with no discriminants, and conformance
5904 -- checking on an inherited operation may compare the actual with the
5905 -- subtype that renames it in the instance.
5907 elsif Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
5910 Is_Generic_Actual_Type (T1) or else Is_Generic_Actual_Type (T2);
5914 elsif Is_Array_Type (T1) then
5916 -- If either subtype is unconstrained then both must be, and if both
5917 -- are unconstrained then no further checking is needed.
5919 if not Is_Constrained (T1) or else not Is_Constrained (T2) then
5920 return not (Is_Constrained (T1) or else Is_Constrained (T2));
5923 -- Both subtypes are constrained, so check that the index subtypes
5924 -- statically match.
5927 Index1 : Node_Id := First_Index (T1);
5928 Index2 : Node_Id := First_Index (T2);
5931 while Present (Index1) loop
5933 Subtypes_Statically_Match (Etype (Index1), Etype (Index2))
5938 Next_Index (Index1);
5939 Next_Index (Index2);
5945 elsif Is_Access_Type (T1) then
5946 if Can_Never_Be_Null (T1) /= Can_Never_Be_Null (T2) then
5949 elsif Ekind_In (T1, E_Access_Subprogram_Type,
5950 E_Anonymous_Access_Subprogram_Type)
5954 (Designated_Type (T1),
5955 Designated_Type (T2));
5958 Subtypes_Statically_Match
5959 (Designated_Type (T1),
5960 Designated_Type (T2))
5961 and then Is_Access_Constant (T1) = Is_Access_Constant (T2);
5964 -- All other types definitely match
5969 end Subtypes_Statically_Match;
5975 function Test (Cond : Boolean) return Uint is
5984 ---------------------------------
5985 -- Test_Expression_Is_Foldable --
5986 ---------------------------------
5990 procedure Test_Expression_Is_Foldable
6000 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
6004 -- If operand is Any_Type, just propagate to result and do not
6005 -- try to fold, this prevents cascaded errors.
6007 if Etype (Op1) = Any_Type then
6008 Set_Etype (N, Any_Type);
6011 -- If operand raises constraint error, then replace node N with the
6012 -- raise constraint error node, and we are obviously not foldable.
6013 -- Note that this replacement inherits the Is_Static_Expression flag
6014 -- from the operand.
6016 elsif Raises_Constraint_Error (Op1) then
6017 Rewrite_In_Raise_CE (N, Op1);
6020 -- If the operand is not static, then the result is not static, and
6021 -- all we have to do is to check the operand since it is now known
6022 -- to appear in a non-static context.
6024 elsif not Is_Static_Expression (Op1) then
6025 Check_Non_Static_Context (Op1);
6026 Fold := Compile_Time_Known_Value (Op1);
6029 -- An expression of a formal modular type is not foldable because
6030 -- the modulus is unknown.
6032 elsif Is_Modular_Integer_Type (Etype (Op1))
6033 and then Is_Generic_Type (Etype (Op1))
6035 Check_Non_Static_Context (Op1);
6038 -- Here we have the case of an operand whose type is OK, which is
6039 -- static, and which does not raise constraint error, we can fold.
6042 Set_Is_Static_Expression (N);
6046 end Test_Expression_Is_Foldable;
6050 procedure Test_Expression_Is_Foldable
6056 CRT_Safe : Boolean := False)
6058 Rstat : constant Boolean := Is_Static_Expression (Op1)
6060 Is_Static_Expression (Op2);
6066 -- Inhibit folding if -gnatd.f flag set
6068 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
6072 -- If either operand is Any_Type, just propagate to result and
6073 -- do not try to fold, this prevents cascaded errors.
6075 if Etype (Op1) = Any_Type or else Etype (Op2) = Any_Type then
6076 Set_Etype (N, Any_Type);
6079 -- If left operand raises constraint error, then replace node N with the
6080 -- Raise_Constraint_Error node, and we are obviously not foldable.
6081 -- Is_Static_Expression is set from the two operands in the normal way,
6082 -- and we check the right operand if it is in a non-static context.
6084 elsif Raises_Constraint_Error (Op1) then
6086 Check_Non_Static_Context (Op2);
6089 Rewrite_In_Raise_CE (N, Op1);
6090 Set_Is_Static_Expression (N, Rstat);
6093 -- Similar processing for the case of the right operand. Note that we
6094 -- don't use this routine for the short-circuit case, so we do not have
6095 -- to worry about that special case here.
6097 elsif Raises_Constraint_Error (Op2) then
6099 Check_Non_Static_Context (Op1);
6102 Rewrite_In_Raise_CE (N, Op2);
6103 Set_Is_Static_Expression (N, Rstat);
6106 -- Exclude expressions of a generic modular type, as above
6108 elsif Is_Modular_Integer_Type (Etype (Op1))
6109 and then Is_Generic_Type (Etype (Op1))
6111 Check_Non_Static_Context (Op1);
6114 -- If result is not static, then check non-static contexts on operands
6115 -- since one of them may be static and the other one may not be static.
6117 elsif not Rstat then
6118 Check_Non_Static_Context (Op1);
6119 Check_Non_Static_Context (Op2);
6122 Fold := CRT_Safe_Compile_Time_Known_Value (Op1)
6123 and then CRT_Safe_Compile_Time_Known_Value (Op2);
6125 Fold := Compile_Time_Known_Value (Op1)
6126 and then Compile_Time_Known_Value (Op2);
6131 -- Else result is static and foldable. Both operands are static, and
6132 -- neither raises constraint error, so we can definitely fold.
6135 Set_Is_Static_Expression (N);
6140 end Test_Expression_Is_Foldable;
6146 function Test_In_Range
6149 Assume_Valid : Boolean;
6150 Fixed_Int : Boolean;
6151 Int_Real : Boolean) return Range_Membership
6156 pragma Warnings (Off, Assume_Valid);
6157 -- For now Assume_Valid is unreferenced since the current implementation
6158 -- always returns Unknown if N is not a compile time known value, but we
6159 -- keep the parameter to allow for future enhancements in which we try
6160 -- to get the information in the variable case as well.
6163 -- If an error was posted on expression, then return Unknown, we do not
6164 -- want cascaded errors based on some false analysis of a junk node.
6166 if Error_Posted (N) then
6169 -- Expression that raises constraint error is an odd case. We certainly
6170 -- do not want to consider it to be in range. It might make sense to
6171 -- consider it always out of range, but this causes incorrect error
6172 -- messages about static expressions out of range. So we just return
6173 -- Unknown, which is always safe.
6175 elsif Raises_Constraint_Error (N) then
6178 -- Universal types have no range limits, so always in range
6180 elsif Typ = Universal_Integer or else Typ = Universal_Real then
6183 -- Never known if not scalar type. Don't know if this can actually
6184 -- happen, but our spec allows it, so we must check.
6186 elsif not Is_Scalar_Type (Typ) then
6189 -- Never known if this is a generic type, since the bounds of generic
6190 -- types are junk. Note that if we only checked for static expressions
6191 -- (instead of compile time known values) below, we would not need this
6192 -- check, because values of a generic type can never be static, but they
6193 -- can be known at compile time.
6195 elsif Is_Generic_Type (Typ) then
6198 -- Case of a known compile time value, where we can check if it is in
6199 -- the bounds of the given type.
6201 elsif Compile_Time_Known_Value (N) then
6210 Lo := Type_Low_Bound (Typ);
6211 Hi := Type_High_Bound (Typ);
6213 LB_Known := Compile_Time_Known_Value (Lo);
6214 HB_Known := Compile_Time_Known_Value (Hi);
6216 -- Fixed point types should be considered as such only if flag
6217 -- Fixed_Int is set to False.
6219 if Is_Floating_Point_Type (Typ)
6220 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
6223 Valr := Expr_Value_R (N);
6225 if LB_Known and HB_Known then
6226 if Valr >= Expr_Value_R (Lo)
6228 Valr <= Expr_Value_R (Hi)
6232 return Out_Of_Range;
6235 elsif (LB_Known and then Valr < Expr_Value_R (Lo))
6237 (HB_Known and then Valr > Expr_Value_R (Hi))
6239 return Out_Of_Range;
6246 Val := Expr_Value (N);
6248 if LB_Known and HB_Known then
6249 if Val >= Expr_Value (Lo) and then Val <= Expr_Value (Hi)
6253 return Out_Of_Range;
6256 elsif (LB_Known and then Val < Expr_Value (Lo))
6258 (HB_Known and then Val > Expr_Value (Hi))
6260 return Out_Of_Range;
6268 -- Here for value not known at compile time. Case of expression subtype
6269 -- is Typ or is a subtype of Typ, and we can assume expression is valid.
6270 -- In this case we know it is in range without knowing its value.
6273 and then (Etype (N) = Typ or else Is_Subtype_Of (Etype (N), Typ))
6277 -- Another special case. For signed integer types, if the target type
6278 -- has Is_Known_Valid set, and the source type does not have a larger
6279 -- size, then the source value must be in range. We exclude biased
6280 -- types, because they bizarrely can generate out of range values.
6282 elsif Is_Signed_Integer_Type (Etype (N))
6283 and then Is_Known_Valid (Typ)
6284 and then Esize (Etype (N)) <= Esize (Typ)
6285 and then not Has_Biased_Representation (Etype (N))
6289 -- For all other cases, result is unknown
6300 procedure To_Bits (U : Uint; B : out Bits) is
6302 for J in 0 .. B'Last loop
6303 B (J) := (U / (2 ** J)) mod 2 /= 0;
6307 --------------------
6308 -- Why_Not_Static --
6309 --------------------
6311 procedure Why_Not_Static (Expr : Node_Id) is
6312 N : constant Node_Id := Original_Node (Expr);
6318 procedure Why_Not_Static_List (L : List_Id);
6319 -- A version that can be called on a list of expressions. Finds all
6320 -- non-static violations in any element of the list.
6322 -------------------------
6323 -- Why_Not_Static_List --
6324 -------------------------
6326 procedure Why_Not_Static_List (L : List_Id) is
6329 if Is_Non_Empty_List (L) then
6331 while Present (N) loop
6336 end Why_Not_Static_List;
6338 -- Start of processing for Why_Not_Static
6341 -- Ignore call on error or empty node
6343 if No (Expr) or else Nkind (Expr) = N_Error then
6347 -- Preprocessing for sub expressions
6349 if Nkind (Expr) in N_Subexpr then
6351 -- Nothing to do if expression is static
6353 if Is_OK_Static_Expression (Expr) then
6357 -- Test for constraint error raised
6359 if Raises_Constraint_Error (Expr) then
6361 -- Special case membership to find out which piece to flag
6363 if Nkind (N) in N_Membership_Test then
6364 if Raises_Constraint_Error (Left_Opnd (N)) then
6365 Why_Not_Static (Left_Opnd (N));
6368 elsif Present (Right_Opnd (N))
6369 and then Raises_Constraint_Error (Right_Opnd (N))
6371 Why_Not_Static (Right_Opnd (N));
6375 pragma Assert (Present (Alternatives (N)));
6377 Alt := First (Alternatives (N));
6378 while Present (Alt) loop
6379 if Raises_Constraint_Error (Alt) then
6380 Why_Not_Static (Alt);
6388 -- Special case a range to find out which bound to flag
6390 elsif Nkind (N) = N_Range then
6391 if Raises_Constraint_Error (Low_Bound (N)) then
6392 Why_Not_Static (Low_Bound (N));
6395 elsif Raises_Constraint_Error (High_Bound (N)) then
6396 Why_Not_Static (High_Bound (N));
6400 -- Special case attribute to see which part to flag
6402 elsif Nkind (N) = N_Attribute_Reference then
6403 if Raises_Constraint_Error (Prefix (N)) then
6404 Why_Not_Static (Prefix (N));
6408 if Present (Expressions (N)) then
6409 Exp := First (Expressions (N));
6410 while Present (Exp) loop
6411 if Raises_Constraint_Error (Exp) then
6412 Why_Not_Static (Exp);
6420 -- Special case a subtype name
6422 elsif Is_Entity_Name (Expr) and then Is_Type (Entity (Expr)) then
6424 ("!& is not a static subtype (RM 4.9(26))", N, Entity (Expr));
6428 -- End of special cases
6431 ("!expression raises exception, cannot be static (RM 4.9(34))",
6436 -- If no type, then something is pretty wrong, so ignore
6438 Typ := Etype (Expr);
6444 -- Type must be scalar or string type (but allow Bignum, since this
6445 -- is really a scalar type from our point of view in this diagnosis).
6447 if not Is_Scalar_Type (Typ)
6448 and then not Is_String_Type (Typ)
6449 and then not Is_RTE (Typ, RE_Bignum)
6452 ("!static expression must have scalar or string type " &
6458 -- If we got through those checks, test particular node kind
6464 when N_Expanded_Name | N_Identifier | N_Operator_Symbol =>
6467 if Is_Named_Number (E) then
6470 elsif Ekind (E) = E_Constant then
6472 -- One case we can give a metter message is when we have a
6473 -- string literal created by concatenating an aggregate with
6474 -- an others expression.
6476 Entity_Case : declare
6477 CV : constant Node_Id := Constant_Value (E);
6478 CO : constant Node_Id := Original_Node (CV);
6480 function Is_Aggregate (N : Node_Id) return Boolean;
6481 -- See if node N came from an others aggregate, if so
6482 -- return True and set Error_Msg_Sloc to aggregate.
6488 function Is_Aggregate (N : Node_Id) return Boolean is
6490 if Nkind (Original_Node (N)) = N_Aggregate then
6491 Error_Msg_Sloc := Sloc (Original_Node (N));
6494 elsif Is_Entity_Name (N)
6495 and then Ekind (Entity (N)) = E_Constant
6497 Nkind (Original_Node (Constant_Value (Entity (N)))) =
6501 Sloc (Original_Node (Constant_Value (Entity (N))));
6509 -- Start of processing for Entity_Case
6512 if Is_Aggregate (CV)
6513 or else (Nkind (CO) = N_Op_Concat
6514 and then (Is_Aggregate (Left_Opnd (CO))
6516 Is_Aggregate (Right_Opnd (CO))))
6518 Error_Msg_N ("!aggregate (#) is never static", N);
6520 elsif No (CV) or else not Is_Static_Expression (CV) then
6522 ("!& is not a static constant (RM 4.9(5))", N, E);
6526 elsif Is_Type (E) then
6528 ("!& is not a static subtype (RM 4.9(26))", N, E);
6532 ("!& is not static constant or named number "
6533 & "(RM 4.9(5))", N, E);
6538 when N_Binary_Op | N_Short_Circuit | N_Membership_Test =>
6539 if Nkind (N) in N_Op_Shift then
6541 ("!shift functions are never static (RM 4.9(6,18))", N);
6543 Why_Not_Static (Left_Opnd (N));
6544 Why_Not_Static (Right_Opnd (N));
6550 Why_Not_Static (Right_Opnd (N));
6552 -- Attribute reference
6554 when N_Attribute_Reference =>
6555 Why_Not_Static_List (Expressions (N));
6557 E := Etype (Prefix (N));
6559 if E = Standard_Void_Type then
6563 -- Special case non-scalar'Size since this is a common error
6565 if Attribute_Name (N) = Name_Size then
6567 ("!size attribute is only static for static scalar type "
6568 & "(RM 4.9(7,8))", N);
6572 elsif Is_Array_Type (E) then
6573 if not Nam_In (Attribute_Name (N), Name_First,
6578 ("!static array attribute must be Length, First, or Last "
6579 & "(RM 4.9(8))", N);
6581 -- Since we know the expression is not-static (we already
6582 -- tested for this, must mean array is not static).
6586 ("!prefix is non-static array (RM 4.9(8))", Prefix (N));
6591 -- Special case generic types, since again this is a common source
6594 elsif Is_Generic_Actual_Type (E) or else Is_Generic_Type (E) then
6596 ("!attribute of generic type is never static "
6597 & "(RM 4.9(7,8))", N);
6599 elsif Is_OK_Static_Subtype (E) then
6602 elsif Is_Scalar_Type (E) then
6604 ("!prefix type for attribute is not static scalar subtype "
6605 & "(RM 4.9(7))", N);
6609 ("!static attribute must apply to array/scalar type "
6610 & "(RM 4.9(7,8))", N);
6615 when N_String_Literal =>
6617 ("!subtype of string literal is non-static (RM 4.9(4))", N);
6619 -- Explicit dereference
6621 when N_Explicit_Dereference =>
6623 ("!explicit dereference is never static (RM 4.9)", N);
6627 when N_Function_Call =>
6628 Why_Not_Static_List (Parameter_Associations (N));
6630 -- Complain about non-static function call unless we have Bignum
6631 -- which means that the underlying expression is really some
6632 -- scalar arithmetic operation.
6634 if not Is_RTE (Typ, RE_Bignum) then
6635 Error_Msg_N ("!non-static function call (RM 4.9(6,18))", N);
6638 -- Parameter assocation (test actual parameter)
6640 when N_Parameter_Association =>
6641 Why_Not_Static (Explicit_Actual_Parameter (N));
6643 -- Indexed component
6645 when N_Indexed_Component =>
6646 Error_Msg_N ("!indexed component is never static (RM 4.9)", N);
6650 when N_Procedure_Call_Statement =>
6651 Error_Msg_N ("!procedure call is never static (RM 4.9)", N);
6653 -- Qualified expression (test expression)
6655 when N_Qualified_Expression =>
6656 Why_Not_Static (Expression (N));
6660 when N_Aggregate | N_Extension_Aggregate =>
6661 Error_Msg_N ("!an aggregate is never static (RM 4.9)", N);
6666 Why_Not_Static (Low_Bound (N));
6667 Why_Not_Static (High_Bound (N));
6669 -- Range constraint, test range expression
6671 when N_Range_Constraint =>
6672 Why_Not_Static (Range_Expression (N));
6674 -- Subtype indication, test constraint
6676 when N_Subtype_Indication =>
6677 Why_Not_Static (Constraint (N));
6679 -- Selected component
6681 when N_Selected_Component =>
6682 Error_Msg_N ("!selected component is never static (RM 4.9)", N);
6687 Error_Msg_N ("!slice is never static (RM 4.9)", N);
6689 when N_Type_Conversion =>
6690 Why_Not_Static (Expression (N));
6692 if not Is_Scalar_Type (Entity (Subtype_Mark (N)))
6693 or else not Is_OK_Static_Subtype (Entity (Subtype_Mark (N)))
6696 ("!static conversion requires static scalar subtype result "
6697 & "(RM 4.9(9))", N);
6700 -- Unchecked type conversion
6702 when N_Unchecked_Type_Conversion =>
6704 ("!unchecked type conversion is never static (RM 4.9)", N);
6706 -- All other cases, no reason to give