1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2009, 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;
35 with Namet; use Namet;
36 with Nmake; use Nmake;
37 with Nlists; use Nlists;
40 with Sem_Aux; use Sem_Aux;
41 with Sem_Cat; use Sem_Cat;
42 with Sem_Ch6; use Sem_Ch6;
43 with Sem_Ch8; use Sem_Ch8;
44 with Sem_Res; use Sem_Res;
45 with Sem_Util; use Sem_Util;
46 with Sem_Type; use Sem_Type;
47 with Sem_Warn; use Sem_Warn;
48 with Sinfo; use Sinfo;
49 with Snames; use Snames;
50 with Stand; use Stand;
51 with Stringt; use Stringt;
52 with Tbuild; use Tbuild;
54 package body Sem_Eval is
56 -----------------------------------------
57 -- Handling of Compile Time Evaluation --
58 -----------------------------------------
60 -- The compile time evaluation of expressions is distributed over several
61 -- Eval_xxx procedures. These procedures are called immediately after
62 -- a subexpression is resolved and is therefore accomplished in a bottom
63 -- up fashion. The flags are synthesized using the following approach.
65 -- Is_Static_Expression is determined by following the detailed rules
66 -- in RM 4.9(4-14). This involves testing the Is_Static_Expression
67 -- flag of the operands in many cases.
69 -- Raises_Constraint_Error is set if any of the operands have the flag
70 -- set or if an attempt to compute the value of the current expression
71 -- results in detection of a runtime constraint error.
73 -- As described in the spec, the requirement is that Is_Static_Expression
74 -- be accurately set, and in addition for nodes for which this flag is set,
75 -- Raises_Constraint_Error must also be set. Furthermore a node which has
76 -- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
77 -- requirement is that the expression value must be precomputed, and the
78 -- node is either a literal, or the name of a constant entity whose value
79 -- is a static expression.
81 -- The general approach is as follows. First compute Is_Static_Expression.
82 -- If the node is not static, then the flag is left off in the node and
83 -- we are all done. Otherwise for a static node, we test if any of the
84 -- operands will raise constraint error, and if so, propagate the flag
85 -- Raises_Constraint_Error to the result node and we are done (since the
86 -- error was already posted at a lower level).
88 -- For the case of a static node whose operands do not raise constraint
89 -- error, we attempt to evaluate the node. If this evaluation succeeds,
90 -- then the node is replaced by the result of this computation. If the
91 -- evaluation raises constraint error, then we rewrite the node with
92 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
93 -- to post appropriate error messages.
99 type Bits is array (Nat range <>) of Boolean;
100 -- Used to convert unsigned (modular) values for folding logical ops
102 -- The following definitions are used to maintain a cache of nodes that
103 -- have compile time known values. The cache is maintained only for
104 -- discrete types (the most common case), and is populated by calls to
105 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
106 -- since it is possible for the status to change (in particular it is
107 -- possible for a node to get replaced by a constraint error node).
109 CV_Bits : constant := 5;
110 -- Number of low order bits of Node_Id value used to reference entries
111 -- in the cache table.
113 CV_Cache_Size : constant Nat := 2 ** CV_Bits;
114 -- Size of cache for compile time values
116 subtype CV_Range is Nat range 0 .. CV_Cache_Size;
118 type CV_Entry is record
123 type CV_Cache_Array is array (CV_Range) of CV_Entry;
125 CV_Cache : CV_Cache_Array := (others => (Node_High_Bound, Uint_0));
126 -- This is the actual cache, with entries consisting of node/value pairs,
127 -- and the impossible value Node_High_Bound used for unset entries.
129 -----------------------
130 -- Local Subprograms --
131 -----------------------
133 function From_Bits (B : Bits; T : Entity_Id) return Uint;
134 -- Converts a bit string of length B'Length to a Uint value to be used
135 -- for a target of type T, which is a modular type. This procedure
136 -- includes the necessary reduction by the modulus in the case of a
137 -- non-binary modulus (for a binary modulus, the bit string is the
138 -- right length any way so all is well).
140 function Get_String_Val (N : Node_Id) return Node_Id;
141 -- Given a tree node for a folded string or character value, returns
142 -- the corresponding string literal or character literal (one of the
143 -- two must be available, or the operand would not have been marked
144 -- as foldable in the earlier analysis of the operation).
146 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean;
147 -- Bits represents the number of bits in an integer value to be computed
148 -- (but the value has not been computed yet). If this value in Bits is
149 -- reasonable, a result of True is returned, with the implication that
150 -- the caller should go ahead and complete the calculation. If the value
151 -- in Bits is unreasonably large, then an error is posted on node N, and
152 -- False is returned (and the caller skips the proposed calculation).
154 procedure Out_Of_Range (N : Node_Id);
155 -- This procedure is called if it is determined that node N, which
156 -- appears in a non-static context, is a compile time known value
157 -- which is outside its range, i.e. the range of Etype. This is used
158 -- in contexts where this is an illegality if N is static, and should
159 -- generate a warning otherwise.
161 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id);
162 -- N and Exp are nodes representing an expression, Exp is known
163 -- to raise CE. N is rewritten in term of Exp in the optimal way.
165 function String_Type_Len (Stype : Entity_Id) return Uint;
166 -- Given a string type, determines the length of the index type, or,
167 -- if this index type is non-static, the length of the base type of
168 -- this index type. Note that if the string type is itself static,
169 -- then the index type is static, so the second case applies only
170 -- if the string type passed is non-static.
172 function Test (Cond : Boolean) return Uint;
173 pragma Inline (Test);
174 -- This function simply returns the appropriate Boolean'Pos value
175 -- corresponding to the value of Cond as a universal integer. It is
176 -- used for producing the result of the static evaluation of the
179 procedure Test_Expression_Is_Foldable
184 -- Tests to see if expression N whose single operand is Op1 is foldable,
185 -- i.e. the operand value is known at compile time. If the operation is
186 -- foldable, then Fold is True on return, and Stat indicates whether
187 -- the result is static (i.e. both operands were static). Note that it
188 -- is quite possible for Fold to be True, and Stat to be False, since
189 -- there are cases in which we know the value of an operand even though
190 -- it is not technically static (e.g. the static lower bound of a range
191 -- whose upper bound is non-static).
193 -- If Stat is set False on return, then Test_Expression_Is_Foldable makes a
194 -- call to Check_Non_Static_Context on the operand. If Fold is False on
195 -- return, then all processing is complete, and the caller should
196 -- return, since there is nothing else to do.
198 -- If Stat is set True on return, then Is_Static_Expression is also set
199 -- true in node N. There are some cases where this is over-enthusiastic,
200 -- e.g. in the two operand case below, for string comaprison, the result
201 -- is not static even though the two operands are static. In such cases,
202 -- the caller must reset the Is_Static_Expression flag in N.
204 procedure Test_Expression_Is_Foldable
210 -- Same processing, except applies to an expression N with two operands
213 procedure To_Bits (U : Uint; B : out Bits);
214 -- Converts a Uint value to a bit string of length B'Length
216 ------------------------------
217 -- Check_Non_Static_Context --
218 ------------------------------
220 procedure Check_Non_Static_Context (N : Node_Id) is
221 T : constant Entity_Id := Etype (N);
222 Checks_On : constant Boolean :=
223 not Index_Checks_Suppressed (T)
224 and not Range_Checks_Suppressed (T);
227 -- Ignore cases of non-scalar types or error types
229 if T = Any_Type or else not Is_Scalar_Type (T) then
233 -- At this stage we have a scalar type. If we have an expression
234 -- that raises CE, then we already issued a warning or error msg
235 -- so there is nothing more to be done in this routine.
237 if Raises_Constraint_Error (N) then
241 -- Now we have a scalar type which is not marked as raising a
242 -- constraint error exception. The main purpose of this routine
243 -- is to deal with static expressions appearing in a non-static
244 -- context. That means that if we do not have a static expression
245 -- then there is not much to do. The one case that we deal with
246 -- here is that if we have a floating-point value that is out of
247 -- range, then we post a warning that an infinity will result.
249 if not Is_Static_Expression (N) then
250 if Is_Floating_Point_Type (T)
251 and then Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True)
254 ("?float value out of range, infinity will be generated", N);
260 -- Here we have the case of outer level static expression of
261 -- scalar type, where the processing of this procedure is needed.
263 -- For real types, this is where we convert the value to a machine
264 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should
265 -- only need to do this if the parent is a constant declaration,
266 -- since in other cases, gigi should do the necessary conversion
267 -- correctly, but experimentation shows that this is not the case
268 -- on all machines, in particular if we do not convert all literals
269 -- to machine values in non-static contexts, then ACVC test C490001
270 -- fails on Sparc/Solaris and SGI/Irix.
272 if Nkind (N) = N_Real_Literal
273 and then not Is_Machine_Number (N)
274 and then not Is_Generic_Type (Etype (N))
275 and then Etype (N) /= Universal_Real
277 -- Check that value is in bounds before converting to machine
278 -- number, so as not to lose case where value overflows in the
279 -- least significant bit or less. See B490001.
281 if Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True) then
286 -- Note: we have to copy the node, to avoid problems with conformance
287 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
289 Rewrite (N, New_Copy (N));
291 if not Is_Floating_Point_Type (T) then
293 (N, Corresponding_Integer_Value (N) * Small_Value (T));
295 elsif not UR_Is_Zero (Realval (N)) then
297 -- Note: even though RM 4.9(38) specifies biased rounding,
298 -- this has been modified by AI-100 in order to prevent
299 -- confusing differences in rounding between static and
300 -- non-static expressions. AI-100 specifies that the effect
301 -- of such rounding is implementation dependent, and in GNAT
302 -- we round to nearest even to match the run-time behavior.
305 (N, Machine (Base_Type (T), Realval (N), Round_Even, N));
308 Set_Is_Machine_Number (N);
311 -- Check for out of range universal integer. This is a non-static
312 -- context, so the integer value must be in range of the runtime
313 -- representation of universal integers.
315 -- We do this only within an expression, because that is the only
316 -- case in which non-static universal integer values can occur, and
317 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
318 -- called in contexts like the expression of a number declaration where
319 -- we certainly want to allow out of range values.
321 if Etype (N) = Universal_Integer
322 and then Nkind (N) = N_Integer_Literal
323 and then Nkind (Parent (N)) in N_Subexpr
325 (Intval (N) < Expr_Value (Type_Low_Bound (Universal_Integer))
327 Intval (N) > Expr_Value (Type_High_Bound (Universal_Integer)))
329 Apply_Compile_Time_Constraint_Error
330 (N, "non-static universal integer value out of range?",
331 CE_Range_Check_Failed);
333 -- Check out of range of base type
335 elsif Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True) then
338 -- Give warning if outside subtype (where one or both of the bounds of
339 -- the subtype is static). This warning is omitted if the expression
340 -- appears in a range that could be null (warnings are handled elsewhere
343 elsif T /= Base_Type (T)
344 and then Nkind (Parent (N)) /= N_Range
346 if Is_In_Range (N, T, Assume_Valid => True) then
349 elsif Is_Out_Of_Range (N, T, Assume_Valid => True) then
350 Apply_Compile_Time_Constraint_Error
351 (N, "value not in range of}?", CE_Range_Check_Failed);
354 Enable_Range_Check (N);
357 Set_Do_Range_Check (N, False);
360 end Check_Non_Static_Context;
362 ---------------------------------
363 -- Check_String_Literal_Length --
364 ---------------------------------
366 procedure Check_String_Literal_Length (N : Node_Id; Ttype : Entity_Id) is
368 if not Raises_Constraint_Error (N)
369 and then Is_Constrained (Ttype)
372 UI_From_Int (String_Length (Strval (N))) /= String_Type_Len (Ttype)
374 Apply_Compile_Time_Constraint_Error
375 (N, "string length wrong for}?",
376 CE_Length_Check_Failed,
381 end Check_String_Literal_Length;
383 --------------------------
384 -- Compile_Time_Compare --
385 --------------------------
387 function Compile_Time_Compare
389 Assume_Valid : Boolean) return Compare_Result
391 Discard : aliased Uint;
393 return Compile_Time_Compare (L, R, Discard'Access, Assume_Valid);
394 end Compile_Time_Compare;
396 function Compile_Time_Compare
399 Assume_Valid : Boolean;
400 Rec : Boolean := False) return Compare_Result
402 Ltyp : Entity_Id := Underlying_Type (Etype (L));
403 Rtyp : Entity_Id := Underlying_Type (Etype (R));
404 -- These get reset to the base type for the case of entities where
405 -- Is_Known_Valid is not set. This takes care of handling possible
406 -- invalid representations using the value of the base type, in
407 -- accordance with RM 13.9.1(10).
409 Discard : aliased Uint;
411 procedure Compare_Decompose
415 -- This procedure decomposes the node N into an expression node and a
416 -- signed offset, so that the value of N is equal to the value of R plus
417 -- the value V (which may be negative). If no such decomposition is
418 -- possible, then on return R is a copy of N, and V is set to zero.
420 function Compare_Fixup (N : Node_Id) return Node_Id;
421 -- This function deals with replacing 'Last and 'First references with
422 -- their corresponding type bounds, which we then can compare. The
423 -- argument is the original node, the result is the identity, unless we
424 -- have a 'Last/'First reference in which case the value returned is the
425 -- appropriate type bound.
427 function Is_Known_Valid_Operand (Opnd : Node_Id) return Boolean;
428 -- Even if the context does not assume that values are valid, some
429 -- simple cases can be recognized.
431 function Is_Same_Value (L, R : Node_Id) return Boolean;
432 -- Returns True iff L and R represent expressions that definitely
433 -- have identical (but not necessarily compile time known) values
434 -- Indeed the caller is expected to have already dealt with the
435 -- cases of compile time known values, so these are not tested here.
437 -----------------------
438 -- Compare_Decompose --
439 -----------------------
441 procedure Compare_Decompose
447 if Nkind (N) = N_Op_Add
448 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
451 V := Intval (Right_Opnd (N));
454 elsif Nkind (N) = N_Op_Subtract
455 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
458 V := UI_Negate (Intval (Right_Opnd (N)));
461 elsif Nkind (N) = N_Attribute_Reference then
462 if Attribute_Name (N) = Name_Succ then
463 R := First (Expressions (N));
467 elsif Attribute_Name (N) = Name_Pred then
468 R := First (Expressions (N));
476 end Compare_Decompose;
482 function Compare_Fixup (N : Node_Id) return Node_Id is
488 if Nkind (N) = N_Attribute_Reference
489 and then (Attribute_Name (N) = Name_First
491 Attribute_Name (N) = Name_Last)
493 Xtyp := Etype (Prefix (N));
495 -- If we have no type, then just abandon the attempt to do
496 -- a fixup, this is probably the result of some other error.
502 -- Dereference an access type
504 if Is_Access_Type (Xtyp) then
505 Xtyp := Designated_Type (Xtyp);
508 -- If we don't have an array type at this stage, something
509 -- is peculiar, e.g. another error, and we abandon the attempt
512 if not Is_Array_Type (Xtyp) then
516 -- Ignore unconstrained array, since bounds are not meaningful
518 if not Is_Constrained (Xtyp) then
522 if Ekind (Xtyp) = E_String_Literal_Subtype then
523 if Attribute_Name (N) = Name_First then
524 return String_Literal_Low_Bound (Xtyp);
526 else -- Attribute_Name (N) = Name_Last
527 return Make_Integer_Literal (Sloc (N),
528 Intval => Intval (String_Literal_Low_Bound (Xtyp))
529 + String_Literal_Length (Xtyp));
533 -- Find correct index type
535 Indx := First_Index (Xtyp);
537 if Present (Expressions (N)) then
538 Subs := UI_To_Int (Expr_Value (First (Expressions (N))));
540 for J in 2 .. Subs loop
541 Indx := Next_Index (Indx);
545 Xtyp := Etype (Indx);
547 if Attribute_Name (N) = Name_First then
548 return Type_Low_Bound (Xtyp);
550 else -- Attribute_Name (N) = Name_Last
551 return Type_High_Bound (Xtyp);
558 ----------------------------
559 -- Is_Known_Valid_Operand --
560 ----------------------------
562 function Is_Known_Valid_Operand (Opnd : Node_Id) return Boolean is
564 return (Is_Entity_Name (Opnd)
566 (Is_Known_Valid (Entity (Opnd))
567 or else Ekind (Entity (Opnd)) = E_In_Parameter
569 (Ekind (Entity (Opnd)) in Object_Kind
570 and then Present (Current_Value (Entity (Opnd))))))
571 or else Is_OK_Static_Expression (Opnd);
572 end Is_Known_Valid_Operand;
578 function Is_Same_Value (L, R : Node_Id) return Boolean is
579 Lf : constant Node_Id := Compare_Fixup (L);
580 Rf : constant Node_Id := Compare_Fixup (R);
582 function Is_Same_Subscript (L, R : List_Id) return Boolean;
583 -- L, R are the Expressions values from two attribute nodes for First
584 -- or Last attributes. Either may be set to No_List if no expressions
585 -- are present (indicating subscript 1). The result is True if both
586 -- expressions represent the same subscript (note one case is where
587 -- one subscript is missing and the other is explicitly set to 1).
589 -----------------------
590 -- Is_Same_Subscript --
591 -----------------------
593 function Is_Same_Subscript (L, R : List_Id) return Boolean is
599 return Expr_Value (First (R)) = Uint_1;
604 return Expr_Value (First (L)) = Uint_1;
606 return Expr_Value (First (L)) = Expr_Value (First (R));
609 end Is_Same_Subscript;
611 -- Start of processing for Is_Same_Value
614 -- Values are the same if they refer to the same entity and the
615 -- entity is non-volatile. This does not however apply to Float
616 -- types, since we may have two NaN values and they should never
619 if Nkind_In (Lf, N_Identifier, N_Expanded_Name)
620 and then Nkind_In (Rf, N_Identifier, N_Expanded_Name)
621 and then Entity (Lf) = Entity (Rf)
622 and then Present (Entity (Lf))
623 and then not Is_Floating_Point_Type (Etype (L))
624 and then not Is_Volatile_Reference (L)
625 and then not Is_Volatile_Reference (R)
629 -- Or if they are compile time known and identical
631 elsif Compile_Time_Known_Value (Lf)
633 Compile_Time_Known_Value (Rf)
634 and then Expr_Value (Lf) = Expr_Value (Rf)
638 -- False if Nkind of the two nodes is different for remaining cases
640 elsif Nkind (Lf) /= Nkind (Rf) then
643 -- True if both 'First or 'Last values applying to the same entity
644 -- (first and last don't change even if value does). Note that we
645 -- need this even with the calls to Compare_Fixup, to handle the
646 -- case of unconstrained array attributes where Compare_Fixup
647 -- cannot find useful bounds.
649 elsif Nkind (Lf) = N_Attribute_Reference
650 and then Attribute_Name (Lf) = Attribute_Name (Rf)
651 and then (Attribute_Name (Lf) = Name_First
653 Attribute_Name (Lf) = Name_Last)
654 and then Nkind_In (Prefix (Lf), N_Identifier, N_Expanded_Name)
655 and then Nkind_In (Prefix (Rf), N_Identifier, N_Expanded_Name)
656 and then Entity (Prefix (Lf)) = Entity (Prefix (Rf))
657 and then Is_Same_Subscript (Expressions (Lf), Expressions (Rf))
661 -- True if the same selected component from the same record
663 elsif Nkind (Lf) = N_Selected_Component
664 and then Selector_Name (Lf) = Selector_Name (Rf)
665 and then Is_Same_Value (Prefix (Lf), Prefix (Rf))
669 -- True if the same unary operator applied to the same operand
671 elsif Nkind (Lf) in N_Unary_Op
672 and then Is_Same_Value (Right_Opnd (Lf), Right_Opnd (Rf))
676 -- True if the same binary operator applied to the same operands
678 elsif Nkind (Lf) in N_Binary_Op
679 and then Is_Same_Value (Left_Opnd (Lf), Left_Opnd (Rf))
680 and then Is_Same_Value (Right_Opnd (Lf), Right_Opnd (Rf))
684 -- All other cases, we can't tell, so return False
691 -- Start of processing for Compile_Time_Compare
696 -- If either operand could raise constraint error, then we cannot
697 -- know the result at compile time (since CE may be raised!)
699 if not (Cannot_Raise_Constraint_Error (L)
701 Cannot_Raise_Constraint_Error (R))
706 -- Identical operands are most certainly equal
711 -- If expressions have no types, then do not attempt to determine if
712 -- they are the same, since something funny is going on. One case in
713 -- which this happens is during generic template analysis, when bounds
714 -- are not fully analyzed.
716 elsif No (Ltyp) or else No (Rtyp) then
719 -- We do not attempt comparisons for packed arrays arrays represented as
720 -- modular types, where the semantics of comparison is quite different.
722 elsif Is_Packed_Array_Type (Ltyp)
723 and then Is_Modular_Integer_Type (Ltyp)
727 -- For access types, the only time we know the result at compile time
728 -- (apart from identical operands, which we handled already) is if we
729 -- know one operand is null and the other is not, or both operands are
732 elsif Is_Access_Type (Ltyp) then
733 if Known_Null (L) then
734 if Known_Null (R) then
736 elsif Known_Non_Null (R) then
742 elsif Known_Non_Null (L) and then Known_Null (R) then
749 -- Case where comparison involves two compile time known values
751 elsif Compile_Time_Known_Value (L)
752 and then Compile_Time_Known_Value (R)
754 -- For the floating-point case, we have to be a little careful, since
755 -- at compile time we are dealing with universal exact values, but at
756 -- runtime, these will be in non-exact target form. That's why the
757 -- returned results are LE and GE below instead of LT and GT.
759 if Is_Floating_Point_Type (Ltyp)
761 Is_Floating_Point_Type (Rtyp)
764 Lo : constant Ureal := Expr_Value_R (L);
765 Hi : constant Ureal := Expr_Value_R (R);
777 -- For string types, we have two string literals and we proceed to
778 -- compare them using the Ada style dictionary string comparison.
780 elsif not Is_Scalar_Type (Ltyp) then
782 Lstring : constant String_Id := Strval (Expr_Value_S (L));
783 Rstring : constant String_Id := Strval (Expr_Value_S (R));
784 Llen : constant Nat := String_Length (Lstring);
785 Rlen : constant Nat := String_Length (Rstring);
788 for J in 1 .. Nat'Min (Llen, Rlen) loop
790 LC : constant Char_Code := Get_String_Char (Lstring, J);
791 RC : constant Char_Code := Get_String_Char (Rstring, J);
803 elsif Llen > Rlen then
810 -- For remaining scalar cases we know exactly (note that this does
811 -- include the fixed-point case, where we know the run time integer
816 Lo : constant Uint := Expr_Value (L);
817 Hi : constant Uint := Expr_Value (R);
834 -- Cases where at least one operand is not known at compile time
837 -- Remaining checks apply only for discrete types
839 if not Is_Discrete_Type (Ltyp)
840 or else not Is_Discrete_Type (Rtyp)
845 -- Defend against generic types, or actually any expressions that
846 -- contain a reference to a generic type from within a generic
847 -- template. We don't want to do any range analysis of such
848 -- expressions for two reasons. First, the bounds of a generic type
849 -- itself are junk and cannot be used for any kind of analysis.
850 -- Second, we may have a case where the range at run time is indeed
851 -- known, but we don't want to do compile time analysis in the
852 -- template based on that range since in an instance the value may be
853 -- static, and able to be elaborated without reference to the bounds
854 -- of types involved. As an example, consider:
856 -- (F'Pos (F'Last) + 1) > Integer'Last
858 -- The expression on the left side of > is Universal_Integer and thus
859 -- acquires the type Integer for evaluation at run time, and at run
860 -- time it is true that this condition is always False, but within
861 -- an instance F may be a type with a static range greater than the
862 -- range of Integer, and the expression statically evaluates to True.
864 if References_Generic_Formal_Type (L)
866 References_Generic_Formal_Type (R)
871 -- Replace types by base types for the case of entities which are
872 -- not known to have valid representations. This takes care of
873 -- properly dealing with invalid representations.
875 if not Assume_Valid and then not Assume_No_Invalid_Values then
876 if Is_Entity_Name (L) and then not Is_Known_Valid (Entity (L)) then
877 Ltyp := Underlying_Type (Base_Type (Ltyp));
880 if Is_Entity_Name (R) and then not Is_Known_Valid (Entity (R)) then
881 Rtyp := Underlying_Type (Base_Type (Rtyp));
885 -- Try range analysis on variables and see if ranges are disjoint
893 Determine_Range (L, LOK, LLo, LHi, Assume_Valid);
894 Determine_Range (R, ROK, RLo, RHi, Assume_Valid);
908 -- If the range includes a single literal and we can assume
909 -- validity then the result is known even if an operand is
924 elsif not Is_Known_Valid_Operand (L)
925 and then not Assume_Valid
927 if Is_Same_Value (L, R) then
936 -- Here is where we check for comparisons against maximum bounds of
937 -- types, where we know that no value can be outside the bounds of
938 -- the subtype. Note that this routine is allowed to assume that all
939 -- expressions are within their subtype bounds. Callers wishing to
940 -- deal with possibly invalid values must in any case take special
941 -- steps (e.g. conversions to larger types) to avoid this kind of
942 -- optimization, which is always considered to be valid. We do not
943 -- attempt this optimization with generic types, since the type
944 -- bounds may not be meaningful in this case.
946 -- We are in danger of an infinite recursion here. It does not seem
947 -- useful to go more than one level deep, so the parameter Rec is
948 -- used to protect ourselves against this infinite recursion.
952 -- See if we can get a decisive check against one operand and
953 -- a bound of the other operand (four possible tests here).
954 -- Note that we avoid testing junk bounds of a generic type.
956 if not Is_Generic_Type (Rtyp) then
957 case Compile_Time_Compare (L, Type_Low_Bound (Rtyp),
959 Assume_Valid, Rec => True)
961 when LT => return LT;
962 when LE => return LE;
963 when EQ => return LE;
967 case Compile_Time_Compare (L, Type_High_Bound (Rtyp),
969 Assume_Valid, Rec => True)
971 when GT => return GT;
972 when GE => return GE;
973 when EQ => return GE;
978 if not Is_Generic_Type (Ltyp) then
979 case Compile_Time_Compare (Type_Low_Bound (Ltyp), R,
981 Assume_Valid, Rec => True)
983 when GT => return GT;
984 when GE => return GE;
985 when EQ => return GE;
989 case Compile_Time_Compare (Type_High_Bound (Ltyp), R,
991 Assume_Valid, Rec => True)
993 when LT => return LT;
994 when LE => return LE;
995 when EQ => return LE;
1001 -- Next attempt is to decompose the expressions to extract
1002 -- a constant offset resulting from the use of any of the forms:
1009 -- Then we see if the two expressions are the same value, and if so
1010 -- the result is obtained by comparing the offsets.
1019 Compare_Decompose (L, Lnode, Loffs);
1020 Compare_Decompose (R, Rnode, Roffs);
1022 if Is_Same_Value (Lnode, Rnode) then
1023 if Loffs = Roffs then
1026 elsif Loffs < Roffs then
1027 Diff.all := Roffs - Loffs;
1031 Diff.all := Loffs - Roffs;
1037 -- Next attempt is to see if we have an entity compared with a
1038 -- compile time known value, where there is a current value
1039 -- conditional for the entity which can tell us the result.
1043 -- Entity variable (left operand)
1046 -- Value (right operand)
1049 -- If False, we have reversed the operands
1052 -- Comparison operator kind from Get_Current_Value_Condition call
1055 -- Value from Get_Current_Value_Condition call
1060 Result : Compare_Result;
1061 -- Known result before inversion
1064 if Is_Entity_Name (L)
1065 and then Compile_Time_Known_Value (R)
1068 Val := Expr_Value (R);
1071 elsif Is_Entity_Name (R)
1072 and then Compile_Time_Known_Value (L)
1075 Val := Expr_Value (L);
1078 -- That was the last chance at finding a compile time result
1084 Get_Current_Value_Condition (Var, Op, Opn);
1086 -- That was the last chance, so if we got nothing return
1092 Opv := Expr_Value (Opn);
1094 -- We got a comparison, so we might have something interesting
1096 -- Convert LE to LT and GE to GT, just so we have fewer cases
1098 if Op = N_Op_Le then
1102 elsif Op = N_Op_Ge then
1107 -- Deal with equality case
1109 if Op = N_Op_Eq then
1112 elsif Opv < Val then
1118 -- Deal with inequality case
1120 elsif Op = N_Op_Ne then
1127 -- Deal with greater than case
1129 elsif Op = N_Op_Gt then
1132 elsif Opv = Val - 1 then
1138 -- Deal with less than case
1140 else pragma Assert (Op = N_Op_Lt);
1143 elsif Opv = Val + 1 then
1150 -- Deal with inverting result
1154 when GT => return LT;
1155 when GE => return LE;
1156 when LT => return GT;
1157 when LE => return GE;
1158 when others => return Result;
1165 end Compile_Time_Compare;
1167 -------------------------------
1168 -- Compile_Time_Known_Bounds --
1169 -------------------------------
1171 function Compile_Time_Known_Bounds (T : Entity_Id) return Boolean is
1176 if not Is_Array_Type (T) then
1180 Indx := First_Index (T);
1181 while Present (Indx) loop
1182 Typ := Underlying_Type (Etype (Indx));
1184 -- Never look at junk bounds of a generic type
1186 if Is_Generic_Type (Typ) then
1190 -- Otherwise check bounds for compile time known
1192 if not Compile_Time_Known_Value (Type_Low_Bound (Typ)) then
1194 elsif not Compile_Time_Known_Value (Type_High_Bound (Typ)) then
1202 end Compile_Time_Known_Bounds;
1204 ------------------------------
1205 -- Compile_Time_Known_Value --
1206 ------------------------------
1208 function Compile_Time_Known_Value (Op : Node_Id) return Boolean is
1209 K : constant Node_Kind := Nkind (Op);
1210 CV_Ent : CV_Entry renames CV_Cache (Nat (Op) mod CV_Cache_Size);
1213 -- Never known at compile time if bad type or raises constraint error
1214 -- or empty (latter case occurs only as a result of a previous error)
1218 or else Etype (Op) = Any_Type
1219 or else Raises_Constraint_Error (Op)
1224 -- If this is not a static expression or a null literal, and we are in
1225 -- configurable run-time mode, then we consider it not known at compile
1226 -- time. This avoids anomalies where whether something is allowed with a
1227 -- given configurable run-time library depends on how good the compiler
1228 -- is at optimizing and knowing that things are constant when they are
1231 if Configurable_Run_Time_Mode
1232 and then K /= N_Null
1233 and then not Is_Static_Expression (Op)
1238 -- If we have an entity name, then see if it is the name of a constant
1239 -- and if so, test the corresponding constant value, or the name of
1240 -- an enumeration literal, which is always a constant.
1242 if Present (Etype (Op)) and then Is_Entity_Name (Op) then
1244 E : constant Entity_Id := Entity (Op);
1248 -- Never known at compile time if it is a packed array value.
1249 -- We might want to try to evaluate these at compile time one
1250 -- day, but we do not make that attempt now.
1252 if Is_Packed_Array_Type (Etype (Op)) then
1256 if Ekind (E) = E_Enumeration_Literal then
1259 elsif Ekind (E) = E_Constant then
1260 V := Constant_Value (E);
1261 return Present (V) and then Compile_Time_Known_Value (V);
1265 -- We have a value, see if it is compile time known
1268 -- Integer literals are worth storing in the cache
1270 if K = N_Integer_Literal then
1272 CV_Ent.V := Intval (Op);
1275 -- Other literals and NULL are known at compile time
1278 K = N_Character_Literal
1282 K = N_String_Literal
1288 -- Any reference to Null_Parameter is known at compile time. No
1289 -- other attribute references (that have not already been folded)
1290 -- are known at compile time.
1292 elsif K = N_Attribute_Reference then
1293 return Attribute_Name (Op) = Name_Null_Parameter;
1297 -- If we fall through, not known at compile time
1301 -- If we get an exception while trying to do this test, then some error
1302 -- has occurred, and we simply say that the value is not known after all
1307 end Compile_Time_Known_Value;
1309 --------------------------------------
1310 -- Compile_Time_Known_Value_Or_Aggr --
1311 --------------------------------------
1313 function Compile_Time_Known_Value_Or_Aggr (Op : Node_Id) return Boolean is
1315 -- If we have an entity name, then see if it is the name of a constant
1316 -- and if so, test the corresponding constant value, or the name of
1317 -- an enumeration literal, which is always a constant.
1319 if Is_Entity_Name (Op) then
1321 E : constant Entity_Id := Entity (Op);
1325 if Ekind (E) = E_Enumeration_Literal then
1328 elsif Ekind (E) /= E_Constant then
1332 V := Constant_Value (E);
1334 and then Compile_Time_Known_Value_Or_Aggr (V);
1338 -- We have a value, see if it is compile time known
1341 if Compile_Time_Known_Value (Op) then
1344 elsif Nkind (Op) = N_Aggregate then
1346 if Present (Expressions (Op)) then
1351 Expr := First (Expressions (Op));
1352 while Present (Expr) loop
1353 if not Compile_Time_Known_Value_Or_Aggr (Expr) then
1362 if Present (Component_Associations (Op)) then
1367 Cass := First (Component_Associations (Op));
1368 while Present (Cass) loop
1370 Compile_Time_Known_Value_Or_Aggr (Expression (Cass))
1382 -- All other types of values are not known at compile time
1389 end Compile_Time_Known_Value_Or_Aggr;
1395 -- This is only called for actuals of functions that are not predefined
1396 -- operators (which have already been rewritten as operators at this
1397 -- stage), so the call can never be folded, and all that needs doing for
1398 -- the actual is to do the check for a non-static context.
1400 procedure Eval_Actual (N : Node_Id) is
1402 Check_Non_Static_Context (N);
1405 --------------------
1406 -- Eval_Allocator --
1407 --------------------
1409 -- Allocators are never static, so all we have to do is to do the
1410 -- check for a non-static context if an expression is present.
1412 procedure Eval_Allocator (N : Node_Id) is
1413 Expr : constant Node_Id := Expression (N);
1416 if Nkind (Expr) = N_Qualified_Expression then
1417 Check_Non_Static_Context (Expression (Expr));
1421 ------------------------
1422 -- Eval_Arithmetic_Op --
1423 ------------------------
1425 -- Arithmetic operations are static functions, so the result is static
1426 -- if both operands are static (RM 4.9(7), 4.9(20)).
1428 procedure Eval_Arithmetic_Op (N : Node_Id) is
1429 Left : constant Node_Id := Left_Opnd (N);
1430 Right : constant Node_Id := Right_Opnd (N);
1431 Ltype : constant Entity_Id := Etype (Left);
1432 Rtype : constant Entity_Id := Etype (Right);
1437 -- If not foldable we are done
1439 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1445 -- Fold for cases where both operands are of integer type
1447 if Is_Integer_Type (Ltype) and then Is_Integer_Type (Rtype) then
1449 Left_Int : constant Uint := Expr_Value (Left);
1450 Right_Int : constant Uint := Expr_Value (Right);
1457 Result := Left_Int + Right_Int;
1459 when N_Op_Subtract =>
1460 Result := Left_Int - Right_Int;
1462 when N_Op_Multiply =>
1465 (Num_Bits (Left_Int) + Num_Bits (Right_Int)))
1467 Result := Left_Int * Right_Int;
1474 -- The exception Constraint_Error is raised by integer
1475 -- division, rem and mod if the right operand is zero.
1477 if Right_Int = 0 then
1478 Apply_Compile_Time_Constraint_Error
1479 (N, "division by zero",
1485 Result := Left_Int / Right_Int;
1490 -- The exception Constraint_Error is raised by integer
1491 -- division, rem and mod if the right operand is zero.
1493 if Right_Int = 0 then
1494 Apply_Compile_Time_Constraint_Error
1495 (N, "mod with zero divisor",
1500 Result := Left_Int mod Right_Int;
1505 -- The exception Constraint_Error is raised by integer
1506 -- division, rem and mod if the right operand is zero.
1508 if Right_Int = 0 then
1509 Apply_Compile_Time_Constraint_Error
1510 (N, "rem with zero divisor",
1516 Result := Left_Int rem Right_Int;
1520 raise Program_Error;
1523 -- Adjust the result by the modulus if the type is a modular type
1525 if Is_Modular_Integer_Type (Ltype) then
1526 Result := Result mod Modulus (Ltype);
1528 -- For a signed integer type, check non-static overflow
1530 elsif (not Stat) and then Is_Signed_Integer_Type (Ltype) then
1532 BT : constant Entity_Id := Base_Type (Ltype);
1533 Lo : constant Uint := Expr_Value (Type_Low_Bound (BT));
1534 Hi : constant Uint := Expr_Value (Type_High_Bound (BT));
1536 if Result < Lo or else Result > Hi then
1537 Apply_Compile_Time_Constraint_Error
1538 (N, "value not in range of }?",
1539 CE_Overflow_Check_Failed,
1546 -- If we get here we can fold the result
1548 Fold_Uint (N, Result, Stat);
1551 -- Cases where at least one operand is a real. We handle the cases
1552 -- of both reals, or mixed/real integer cases (the latter happen
1553 -- only for divide and multiply, and the result is always real).
1555 elsif Is_Real_Type (Ltype) or else Is_Real_Type (Rtype) then
1562 if Is_Real_Type (Ltype) then
1563 Left_Real := Expr_Value_R (Left);
1565 Left_Real := UR_From_Uint (Expr_Value (Left));
1568 if Is_Real_Type (Rtype) then
1569 Right_Real := Expr_Value_R (Right);
1571 Right_Real := UR_From_Uint (Expr_Value (Right));
1574 if Nkind (N) = N_Op_Add then
1575 Result := Left_Real + Right_Real;
1577 elsif Nkind (N) = N_Op_Subtract then
1578 Result := Left_Real - Right_Real;
1580 elsif Nkind (N) = N_Op_Multiply then
1581 Result := Left_Real * Right_Real;
1583 else pragma Assert (Nkind (N) = N_Op_Divide);
1584 if UR_Is_Zero (Right_Real) then
1585 Apply_Compile_Time_Constraint_Error
1586 (N, "division by zero", CE_Divide_By_Zero);
1590 Result := Left_Real / Right_Real;
1593 Fold_Ureal (N, Result, Stat);
1596 end Eval_Arithmetic_Op;
1598 ----------------------------
1599 -- Eval_Character_Literal --
1600 ----------------------------
1602 -- Nothing to be done!
1604 procedure Eval_Character_Literal (N : Node_Id) is
1605 pragma Warnings (Off, N);
1608 end Eval_Character_Literal;
1614 -- Static function calls are either calls to predefined operators
1615 -- with static arguments, or calls to functions that rename a literal.
1616 -- Only the latter case is handled here, predefined operators are
1617 -- constant-folded elsewhere.
1619 -- If the function is itself inherited (see 7423-001) the literal of
1620 -- the parent type must be explicitly converted to the return type
1623 procedure Eval_Call (N : Node_Id) is
1624 Loc : constant Source_Ptr := Sloc (N);
1625 Typ : constant Entity_Id := Etype (N);
1629 if Nkind (N) = N_Function_Call
1630 and then No (Parameter_Associations (N))
1631 and then Is_Entity_Name (Name (N))
1632 and then Present (Alias (Entity (Name (N))))
1633 and then Is_Enumeration_Type (Base_Type (Typ))
1635 Lit := Alias (Entity (Name (N)));
1636 while Present (Alias (Lit)) loop
1640 if Ekind (Lit) = E_Enumeration_Literal then
1641 if Base_Type (Etype (Lit)) /= Base_Type (Typ) then
1643 (N, Convert_To (Typ, New_Occurrence_Of (Lit, Loc)));
1645 Rewrite (N, New_Occurrence_Of (Lit, Loc));
1653 ------------------------
1654 -- Eval_Concatenation --
1655 ------------------------
1657 -- Concatenation is a static function, so the result is static if both
1658 -- operands are static (RM 4.9(7), 4.9(21)).
1660 procedure Eval_Concatenation (N : Node_Id) is
1661 Left : constant Node_Id := Left_Opnd (N);
1662 Right : constant Node_Id := Right_Opnd (N);
1663 C_Typ : constant Entity_Id := Root_Type (Component_Type (Etype (N)));
1668 -- Concatenation is never static in Ada 83, so if Ada 83 check operand
1669 -- non-static context.
1671 if Ada_Version = Ada_83
1672 and then Comes_From_Source (N)
1674 Check_Non_Static_Context (Left);
1675 Check_Non_Static_Context (Right);
1679 -- If not foldable we are done. In principle concatenation that yields
1680 -- any string type is static (i.e. an array type of character types).
1681 -- However, character types can include enumeration literals, and
1682 -- concatenation in that case cannot be described by a literal, so we
1683 -- only consider the operation static if the result is an array of
1684 -- (a descendant of) a predefined character type.
1686 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1688 if not (Is_Standard_Character_Type (C_Typ) and then Fold) then
1689 Set_Is_Static_Expression (N, False);
1693 -- Compile time string concatenation
1695 -- ??? Note that operands that are aggregates can be marked as static,
1696 -- so we should attempt at a later stage to fold concatenations with
1700 Left_Str : constant Node_Id := Get_String_Val (Left);
1702 Right_Str : constant Node_Id := Get_String_Val (Right);
1703 Folded_Val : String_Id;
1706 -- Establish new string literal, and store left operand. We make
1707 -- sure to use the special Start_String that takes an operand if
1708 -- the left operand is a string literal. Since this is optimized
1709 -- in the case where that is the most recently created string
1710 -- literal, we ensure efficient time/space behavior for the
1711 -- case of a concatenation of a series of string literals.
1713 if Nkind (Left_Str) = N_String_Literal then
1714 Left_Len := String_Length (Strval (Left_Str));
1716 -- If the left operand is the empty string, and the right operand
1717 -- is a string literal (the case of "" & "..."), the result is the
1718 -- value of the right operand. This optimization is important when
1719 -- Is_Folded_In_Parser, to avoid copying an enormous right
1722 if Left_Len = 0 and then Nkind (Right_Str) = N_String_Literal then
1723 Folded_Val := Strval (Right_Str);
1725 Start_String (Strval (Left_Str));
1730 Store_String_Char (UI_To_CC (Char_Literal_Value (Left_Str)));
1734 -- Now append the characters of the right operand, unless we
1735 -- optimized the "" & "..." case above.
1737 if Nkind (Right_Str) = N_String_Literal then
1738 if Left_Len /= 0 then
1739 Store_String_Chars (Strval (Right_Str));
1740 Folded_Val := End_String;
1743 Store_String_Char (UI_To_CC (Char_Literal_Value (Right_Str)));
1744 Folded_Val := End_String;
1747 Set_Is_Static_Expression (N, Stat);
1751 -- If left operand is the empty string, the result is the
1752 -- right operand, including its bounds if anomalous.
1755 and then Is_Array_Type (Etype (Right))
1756 and then Etype (Right) /= Any_String
1758 Set_Etype (N, Etype (Right));
1761 Fold_Str (N, Folded_Val, Static => True);
1764 end Eval_Concatenation;
1766 ---------------------------------
1767 -- Eval_Conditional_Expression --
1768 ---------------------------------
1770 -- This GNAT internal construct can never be statically folded, so the
1771 -- only required processing is to do the check for non-static context
1772 -- for the two expression operands.
1774 procedure Eval_Conditional_Expression (N : Node_Id) is
1775 Condition : constant Node_Id := First (Expressions (N));
1776 Then_Expr : constant Node_Id := Next (Condition);
1777 Else_Expr : constant Node_Id := Next (Then_Expr);
1780 Check_Non_Static_Context (Then_Expr);
1781 Check_Non_Static_Context (Else_Expr);
1782 end Eval_Conditional_Expression;
1784 ----------------------
1785 -- Eval_Entity_Name --
1786 ----------------------
1788 -- This procedure is used for identifiers and expanded names other than
1789 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
1790 -- static if they denote a static constant (RM 4.9(6)) or if the name
1791 -- denotes an enumeration literal (RM 4.9(22)).
1793 procedure Eval_Entity_Name (N : Node_Id) is
1794 Def_Id : constant Entity_Id := Entity (N);
1798 -- Enumeration literals are always considered to be constants
1799 -- and cannot raise constraint error (RM 4.9(22)).
1801 if Ekind (Def_Id) = E_Enumeration_Literal then
1802 Set_Is_Static_Expression (N);
1805 -- A name is static if it denotes a static constant (RM 4.9(5)), and
1806 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
1807 -- it does not violate 10.2.1(8) here, since this is not a variable.
1809 elsif Ekind (Def_Id) = E_Constant then
1811 -- Deferred constants must always be treated as nonstatic
1812 -- outside the scope of their full view.
1814 if Present (Full_View (Def_Id))
1815 and then not In_Open_Scopes (Scope (Def_Id))
1819 Val := Constant_Value (Def_Id);
1822 if Present (Val) then
1823 Set_Is_Static_Expression
1824 (N, Is_Static_Expression (Val)
1825 and then Is_Static_Subtype (Etype (Def_Id)));
1826 Set_Raises_Constraint_Error (N, Raises_Constraint_Error (Val));
1828 if not Is_Static_Expression (N)
1829 and then not Is_Generic_Type (Etype (N))
1831 Validate_Static_Object_Name (N);
1838 -- Fall through if the name is not static
1840 Validate_Static_Object_Name (N);
1841 end Eval_Entity_Name;
1843 ----------------------------
1844 -- Eval_Indexed_Component --
1845 ----------------------------
1847 -- Indexed components are never static, so we need to perform the check
1848 -- for non-static context on the index values. Then, we check if the
1849 -- value can be obtained at compile time, even though it is non-static.
1851 procedure Eval_Indexed_Component (N : Node_Id) is
1855 -- Check for non-static context on index values
1857 Expr := First (Expressions (N));
1858 while Present (Expr) loop
1859 Check_Non_Static_Context (Expr);
1863 -- If the indexed component appears in an object renaming declaration
1864 -- then we do not want to try to evaluate it, since in this case we
1865 -- need the identity of the array element.
1867 if Nkind (Parent (N)) = N_Object_Renaming_Declaration then
1870 -- Similarly if the indexed component appears as the prefix of an
1871 -- attribute we don't want to evaluate it, because at least for
1872 -- some cases of attributes we need the identify (e.g. Access, Size)
1874 elsif Nkind (Parent (N)) = N_Attribute_Reference then
1878 -- Note: there are other cases, such as the left side of an assignment,
1879 -- or an OUT parameter for a call, where the replacement results in the
1880 -- illegal use of a constant, But these cases are illegal in the first
1881 -- place, so the replacement, though silly, is harmless.
1883 -- Now see if this is a constant array reference
1885 if List_Length (Expressions (N)) = 1
1886 and then Is_Entity_Name (Prefix (N))
1887 and then Ekind (Entity (Prefix (N))) = E_Constant
1888 and then Present (Constant_Value (Entity (Prefix (N))))
1891 Loc : constant Source_Ptr := Sloc (N);
1892 Arr : constant Node_Id := Constant_Value (Entity (Prefix (N)));
1893 Sub : constant Node_Id := First (Expressions (N));
1899 -- Linear one's origin subscript value for array reference
1902 -- Lower bound of the first array index
1905 -- Value from constant array
1908 Atyp := Etype (Arr);
1910 if Is_Access_Type (Atyp) then
1911 Atyp := Designated_Type (Atyp);
1914 -- If we have an array type (we should have but perhaps there
1915 -- are error cases where this is not the case), then see if we
1916 -- can do a constant evaluation of the array reference.
1918 if Is_Array_Type (Atyp) then
1919 if Ekind (Atyp) = E_String_Literal_Subtype then
1920 Lbd := String_Literal_Low_Bound (Atyp);
1922 Lbd := Type_Low_Bound (Etype (First_Index (Atyp)));
1925 if Compile_Time_Known_Value (Sub)
1926 and then Nkind (Arr) = N_Aggregate
1927 and then Compile_Time_Known_Value (Lbd)
1928 and then Is_Discrete_Type (Component_Type (Atyp))
1930 Lin := UI_To_Int (Expr_Value (Sub) - Expr_Value (Lbd)) + 1;
1932 if List_Length (Expressions (Arr)) >= Lin then
1933 Elm := Pick (Expressions (Arr), Lin);
1935 -- If the resulting expression is compile time known,
1936 -- then we can rewrite the indexed component with this
1937 -- value, being sure to mark the result as non-static.
1938 -- We also reset the Sloc, in case this generates an
1939 -- error later on (e.g. 136'Access).
1941 if Compile_Time_Known_Value (Elm) then
1942 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
1943 Set_Is_Static_Expression (N, False);
1948 -- We can also constant-fold if the prefix is a string literal.
1949 -- This will be useful in an instantiation or an inlining.
1951 elsif Compile_Time_Known_Value (Sub)
1952 and then Nkind (Arr) = N_String_Literal
1953 and then Compile_Time_Known_Value (Lbd)
1954 and then Expr_Value (Lbd) = 1
1955 and then Expr_Value (Sub) <=
1956 String_Literal_Length (Etype (Arr))
1959 C : constant Char_Code :=
1960 Get_String_Char (Strval (Arr),
1961 UI_To_Int (Expr_Value (Sub)));
1963 Set_Character_Literal_Name (C);
1966 Make_Character_Literal (Loc,
1968 Char_Literal_Value => UI_From_CC (C));
1969 Set_Etype (Elm, Component_Type (Atyp));
1970 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
1971 Set_Is_Static_Expression (N, False);
1977 end Eval_Indexed_Component;
1979 --------------------------
1980 -- Eval_Integer_Literal --
1981 --------------------------
1983 -- Numeric literals are static (RM 4.9(1)), and have already been marked
1984 -- as static by the analyzer. The reason we did it that early is to allow
1985 -- the possibility of turning off the Is_Static_Expression flag after
1986 -- analysis, but before resolution, when integer literals are generated
1987 -- in the expander that do not correspond to static expressions.
1989 procedure Eval_Integer_Literal (N : Node_Id) is
1990 T : constant Entity_Id := Etype (N);
1992 function In_Any_Integer_Context return Boolean;
1993 -- If the literal is resolved with a specific type in a context where
1994 -- the expected type is Any_Integer, there are no range checks on the
1995 -- literal. By the time the literal is evaluated, it carries the type
1996 -- imposed by the enclosing expression, and we must recover the context
1997 -- to determine that Any_Integer is meant.
1999 ----------------------------
2000 -- In_Any_Integer_Context --
2001 ----------------------------
2003 function In_Any_Integer_Context return Boolean is
2004 Par : constant Node_Id := Parent (N);
2005 K : constant Node_Kind := Nkind (Par);
2008 -- Any_Integer also appears in digits specifications for real types,
2009 -- but those have bounds smaller that those of any integer base type,
2010 -- so we can safely ignore these cases.
2012 return K = N_Number_Declaration
2013 or else K = N_Attribute_Reference
2014 or else K = N_Attribute_Definition_Clause
2015 or else K = N_Modular_Type_Definition
2016 or else K = N_Signed_Integer_Type_Definition;
2017 end In_Any_Integer_Context;
2019 -- Start of processing for Eval_Integer_Literal
2023 -- If the literal appears in a non-expression context, then it is
2024 -- certainly appearing in a non-static context, so check it. This is
2025 -- actually a redundant check, since Check_Non_Static_Context would
2026 -- check it, but it seems worth while avoiding the call.
2028 if Nkind (Parent (N)) not in N_Subexpr
2029 and then not In_Any_Integer_Context
2031 Check_Non_Static_Context (N);
2034 -- Modular integer literals must be in their base range
2036 if Is_Modular_Integer_Type (T)
2037 and then Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True)
2041 end Eval_Integer_Literal;
2043 ---------------------
2044 -- Eval_Logical_Op --
2045 ---------------------
2047 -- Logical operations are static functions, so the result is potentially
2048 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2050 procedure Eval_Logical_Op (N : Node_Id) is
2051 Left : constant Node_Id := Left_Opnd (N);
2052 Right : constant Node_Id := Right_Opnd (N);
2057 -- If not foldable we are done
2059 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2065 -- Compile time evaluation of logical operation
2068 Left_Int : constant Uint := Expr_Value (Left);
2069 Right_Int : constant Uint := Expr_Value (Right);
2072 if Is_Modular_Integer_Type (Etype (N)) then
2074 Left_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
2075 Right_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
2078 To_Bits (Left_Int, Left_Bits);
2079 To_Bits (Right_Int, Right_Bits);
2081 -- Note: should really be able to use array ops instead of
2082 -- these loops, but they weren't working at the time ???
2084 if Nkind (N) = N_Op_And then
2085 for J in Left_Bits'Range loop
2086 Left_Bits (J) := Left_Bits (J) and Right_Bits (J);
2089 elsif Nkind (N) = N_Op_Or then
2090 for J in Left_Bits'Range loop
2091 Left_Bits (J) := Left_Bits (J) or Right_Bits (J);
2095 pragma Assert (Nkind (N) = N_Op_Xor);
2097 for J in Left_Bits'Range loop
2098 Left_Bits (J) := Left_Bits (J) xor Right_Bits (J);
2102 Fold_Uint (N, From_Bits (Left_Bits, Etype (N)), Stat);
2106 pragma Assert (Is_Boolean_Type (Etype (N)));
2108 if Nkind (N) = N_Op_And then
2110 Test (Is_True (Left_Int) and then Is_True (Right_Int)), Stat);
2112 elsif Nkind (N) = N_Op_Or then
2114 Test (Is_True (Left_Int) or else Is_True (Right_Int)), Stat);
2117 pragma Assert (Nkind (N) = N_Op_Xor);
2119 Test (Is_True (Left_Int) xor Is_True (Right_Int)), Stat);
2123 end Eval_Logical_Op;
2125 ------------------------
2126 -- Eval_Membership_Op --
2127 ------------------------
2129 -- A membership test is potentially static if the expression is static, and
2130 -- the range is a potentially static range, or is a subtype mark denoting a
2131 -- static subtype (RM 4.9(12)).
2133 procedure Eval_Membership_Op (N : Node_Id) is
2134 Left : constant Node_Id := Left_Opnd (N);
2135 Right : constant Node_Id := Right_Opnd (N);
2144 -- Ignore if error in either operand, except to make sure that Any_Type
2145 -- is properly propagated to avoid junk cascaded errors.
2147 if Etype (Left) = Any_Type
2148 or else Etype (Right) = Any_Type
2150 Set_Etype (N, Any_Type);
2154 -- Case of right operand is a subtype name
2156 if Is_Entity_Name (Right) then
2157 Def_Id := Entity (Right);
2159 if (Is_Scalar_Type (Def_Id) or else Is_String_Type (Def_Id))
2160 and then Is_OK_Static_Subtype (Def_Id)
2162 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
2164 if not Fold or else not Stat then
2168 Check_Non_Static_Context (Left);
2172 -- For string membership tests we will check the length further on
2174 if not Is_String_Type (Def_Id) then
2175 Lo := Type_Low_Bound (Def_Id);
2176 Hi := Type_High_Bound (Def_Id);
2183 -- Case of right operand is a range
2186 if Is_Static_Range (Right) then
2187 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
2189 if not Fold or else not Stat then
2192 -- If one bound of range raises CE, then don't try to fold
2194 elsif not Is_OK_Static_Range (Right) then
2195 Check_Non_Static_Context (Left);
2200 Check_Non_Static_Context (Left);
2204 -- Here we know range is an OK static range
2206 Lo := Low_Bound (Right);
2207 Hi := High_Bound (Right);
2210 -- For strings we check that the length of the string expression is
2211 -- compatible with the string subtype if the subtype is constrained,
2212 -- or if unconstrained then the test is always true.
2214 if Is_String_Type (Etype (Right)) then
2215 if not Is_Constrained (Etype (Right)) then
2220 Typlen : constant Uint := String_Type_Len (Etype (Right));
2221 Strlen : constant Uint :=
2222 UI_From_Int (String_Length (Strval (Get_String_Val (Left))));
2224 Result := (Typlen = Strlen);
2228 -- Fold the membership test. We know we have a static range and Lo and
2229 -- Hi are set to the expressions for the end points of this range.
2231 elsif Is_Real_Type (Etype (Right)) then
2233 Leftval : constant Ureal := Expr_Value_R (Left);
2236 Result := Expr_Value_R (Lo) <= Leftval
2237 and then Leftval <= Expr_Value_R (Hi);
2242 Leftval : constant Uint := Expr_Value (Left);
2245 Result := Expr_Value (Lo) <= Leftval
2246 and then Leftval <= Expr_Value (Hi);
2250 if Nkind (N) = N_Not_In then
2251 Result := not Result;
2254 Fold_Uint (N, Test (Result), True);
2255 Warn_On_Known_Condition (N);
2256 end Eval_Membership_Op;
2258 ------------------------
2259 -- Eval_Named_Integer --
2260 ------------------------
2262 procedure Eval_Named_Integer (N : Node_Id) is
2265 Expr_Value (Expression (Declaration_Node (Entity (N)))), True);
2266 end Eval_Named_Integer;
2268 ---------------------
2269 -- Eval_Named_Real --
2270 ---------------------
2272 procedure Eval_Named_Real (N : Node_Id) is
2275 Expr_Value_R (Expression (Declaration_Node (Entity (N)))), True);
2276 end Eval_Named_Real;
2282 -- Exponentiation is a static functions, so the result is potentially
2283 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2285 procedure Eval_Op_Expon (N : Node_Id) is
2286 Left : constant Node_Id := Left_Opnd (N);
2287 Right : constant Node_Id := Right_Opnd (N);
2292 -- If not foldable we are done
2294 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2300 -- Fold exponentiation operation
2303 Right_Int : constant Uint := Expr_Value (Right);
2308 if Is_Integer_Type (Etype (Left)) then
2310 Left_Int : constant Uint := Expr_Value (Left);
2314 -- Exponentiation of an integer raises the exception
2315 -- Constraint_Error for a negative exponent (RM 4.5.6)
2317 if Right_Int < 0 then
2318 Apply_Compile_Time_Constraint_Error
2319 (N, "integer exponent negative",
2320 CE_Range_Check_Failed,
2325 if OK_Bits (N, Num_Bits (Left_Int) * Right_Int) then
2326 Result := Left_Int ** Right_Int;
2331 if Is_Modular_Integer_Type (Etype (N)) then
2332 Result := Result mod Modulus (Etype (N));
2335 Fold_Uint (N, Result, Stat);
2343 Left_Real : constant Ureal := Expr_Value_R (Left);
2346 -- Cannot have a zero base with a negative exponent
2348 if UR_Is_Zero (Left_Real) then
2350 if Right_Int < 0 then
2351 Apply_Compile_Time_Constraint_Error
2352 (N, "zero ** negative integer",
2353 CE_Range_Check_Failed,
2357 Fold_Ureal (N, Ureal_0, Stat);
2361 Fold_Ureal (N, Left_Real ** Right_Int, Stat);
2372 -- The not operation is a static functions, so the result is potentially
2373 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
2375 procedure Eval_Op_Not (N : Node_Id) is
2376 Right : constant Node_Id := Right_Opnd (N);
2381 -- If not foldable we are done
2383 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
2389 -- Fold not operation
2392 Rint : constant Uint := Expr_Value (Right);
2393 Typ : constant Entity_Id := Etype (N);
2396 -- Negation is equivalent to subtracting from the modulus minus one.
2397 -- For a binary modulus this is equivalent to the ones-complement of
2398 -- the original value. For non-binary modulus this is an arbitrary
2399 -- but consistent definition.
2401 if Is_Modular_Integer_Type (Typ) then
2402 Fold_Uint (N, Modulus (Typ) - 1 - Rint, Stat);
2405 pragma Assert (Is_Boolean_Type (Typ));
2406 Fold_Uint (N, Test (not Is_True (Rint)), Stat);
2409 Set_Is_Static_Expression (N, Stat);
2413 -------------------------------
2414 -- Eval_Qualified_Expression --
2415 -------------------------------
2417 -- A qualified expression is potentially static if its subtype mark denotes
2418 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2420 procedure Eval_Qualified_Expression (N : Node_Id) is
2421 Operand : constant Node_Id := Expression (N);
2422 Target_Type : constant Entity_Id := Entity (Subtype_Mark (N));
2429 -- Can only fold if target is string or scalar and subtype is static.
2430 -- Also, do not fold if our parent is an allocator (this is because
2431 -- the qualified expression is really part of the syntactic structure
2432 -- of an allocator, and we do not want to end up with something that
2433 -- corresponds to "new 1" where the 1 is the result of folding a
2434 -- qualified expression).
2436 if not Is_Static_Subtype (Target_Type)
2437 or else Nkind (Parent (N)) = N_Allocator
2439 Check_Non_Static_Context (Operand);
2441 -- If operand is known to raise constraint_error, set the flag on the
2442 -- expression so it does not get optimized away.
2444 if Nkind (Operand) = N_Raise_Constraint_Error then
2445 Set_Raises_Constraint_Error (N);
2451 -- If not foldable we are done
2453 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
2458 -- Don't try fold if target type has constraint error bounds
2460 elsif not Is_OK_Static_Subtype (Target_Type) then
2461 Set_Raises_Constraint_Error (N);
2465 -- Here we will fold, save Print_In_Hex indication
2467 Hex := Nkind (Operand) = N_Integer_Literal
2468 and then Print_In_Hex (Operand);
2470 -- Fold the result of qualification
2472 if Is_Discrete_Type (Target_Type) then
2473 Fold_Uint (N, Expr_Value (Operand), Stat);
2475 -- Preserve Print_In_Hex indication
2477 if Hex and then Nkind (N) = N_Integer_Literal then
2478 Set_Print_In_Hex (N);
2481 elsif Is_Real_Type (Target_Type) then
2482 Fold_Ureal (N, Expr_Value_R (Operand), Stat);
2485 Fold_Str (N, Strval (Get_String_Val (Operand)), Stat);
2488 Set_Is_Static_Expression (N, False);
2490 Check_String_Literal_Length (N, Target_Type);
2496 -- The expression may be foldable but not static
2498 Set_Is_Static_Expression (N, Stat);
2500 if Is_Out_Of_Range (N, Etype (N), Assume_Valid => True) then
2503 end Eval_Qualified_Expression;
2505 -----------------------
2506 -- Eval_Real_Literal --
2507 -----------------------
2509 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2510 -- as static by the analyzer. The reason we did it that early is to allow
2511 -- the possibility of turning off the Is_Static_Expression flag after
2512 -- analysis, but before resolution, when integer literals are generated
2513 -- in the expander that do not correspond to static expressions.
2515 procedure Eval_Real_Literal (N : Node_Id) is
2516 PK : constant Node_Kind := Nkind (Parent (N));
2519 -- If the literal appears in a non-expression context and not as part of
2520 -- a number declaration, then it is appearing in a non-static context,
2523 if PK not in N_Subexpr and then PK /= N_Number_Declaration then
2524 Check_Non_Static_Context (N);
2526 end Eval_Real_Literal;
2528 ------------------------
2529 -- Eval_Relational_Op --
2530 ------------------------
2532 -- Relational operations are static functions, so the result is static
2533 -- if both operands are static (RM 4.9(7), 4.9(20)), except that for
2534 -- strings, the result is never static, even if the operands are.
2536 procedure Eval_Relational_Op (N : Node_Id) is
2537 Left : constant Node_Id := Left_Opnd (N);
2538 Right : constant Node_Id := Right_Opnd (N);
2539 Typ : constant Entity_Id := Etype (Left);
2545 -- One special case to deal with first. If we can tell that the result
2546 -- will be false because the lengths of one or more index subtypes are
2547 -- compile time known and different, then we can replace the entire
2548 -- result by False. We only do this for one dimensional arrays, because
2549 -- the case of multi-dimensional arrays is rare and too much trouble! If
2550 -- one of the operands is an illegal aggregate, its type might still be
2551 -- an arbitrary composite type, so nothing to do.
2553 if Is_Array_Type (Typ)
2554 and then Typ /= Any_Composite
2555 and then Number_Dimensions (Typ) = 1
2556 and then (Nkind (N) = N_Op_Eq or else Nkind (N) = N_Op_Ne)
2558 if Raises_Constraint_Error (Left)
2559 or else Raises_Constraint_Error (Right)
2564 -- OK, we have the case where we may be able to do this fold
2566 Length_Mismatch : declare
2567 procedure Get_Static_Length (Op : Node_Id; Len : out Uint);
2568 -- If Op is an expression for a constrained array with a known at
2569 -- compile time length, then Len is set to this (non-negative
2570 -- length). Otherwise Len is set to minus 1.
2572 -----------------------
2573 -- Get_Static_Length --
2574 -----------------------
2576 procedure Get_Static_Length (Op : Node_Id; Len : out Uint) is
2580 -- First easy case string literal
2582 if Nkind (Op) = N_String_Literal then
2583 Len := UI_From_Int (String_Length (Strval (Op)));
2587 -- Second easy case, not constrained subtype, so no length
2589 if not Is_Constrained (Etype (Op)) then
2590 Len := Uint_Minus_1;
2596 T := Etype (First_Index (Etype (Op)));
2598 -- The simple case, both bounds are known at compile time
2600 if Is_Discrete_Type (T)
2602 Compile_Time_Known_Value (Type_Low_Bound (T))
2604 Compile_Time_Known_Value (Type_High_Bound (T))
2606 Len := UI_Max (Uint_0,
2607 Expr_Value (Type_High_Bound (T)) -
2608 Expr_Value (Type_Low_Bound (T)) + 1);
2612 -- A more complex case, where the bounds are of the form
2613 -- X [+/- K1] .. X [+/- K2]), where X is an expression that is
2614 -- either A'First or A'Last (with A an entity name), or X is an
2615 -- entity name, and the two X's are the same and K1 and K2 are
2616 -- known at compile time, in this case, the length can also be
2617 -- computed at compile time, even though the bounds are not
2618 -- known. A common case of this is e.g. (X'First..X'First+5).
2620 Extract_Length : declare
2621 procedure Decompose_Expr
2623 Ent : out Entity_Id;
2624 Kind : out Character;
2626 -- Given an expression, see if is of the form above,
2627 -- X [+/- K]. If so Ent is set to the entity in X,
2628 -- Kind is 'F','L','E' for 'First/'Last/simple entity,
2629 -- and Cons is the value of K. If the expression is
2630 -- not of the required form, Ent is set to Empty.
2632 --------------------
2633 -- Decompose_Expr --
2634 --------------------
2636 procedure Decompose_Expr
2638 Ent : out Entity_Id;
2639 Kind : out Character;
2645 if Nkind (Expr) = N_Op_Add
2646 and then Compile_Time_Known_Value (Right_Opnd (Expr))
2648 Exp := Left_Opnd (Expr);
2649 Cons := Expr_Value (Right_Opnd (Expr));
2651 elsif Nkind (Expr) = N_Op_Subtract
2652 and then Compile_Time_Known_Value (Right_Opnd (Expr))
2654 Exp := Left_Opnd (Expr);
2655 Cons := -Expr_Value (Right_Opnd (Expr));
2662 -- At this stage Exp is set to the potential X
2664 if Nkind (Exp) = N_Attribute_Reference then
2665 if Attribute_Name (Exp) = Name_First then
2667 elsif Attribute_Name (Exp) = Name_Last then
2674 Exp := Prefix (Exp);
2680 if Is_Entity_Name (Exp)
2681 and then Present (Entity (Exp))
2683 Ent := Entity (Exp);
2691 Ent1, Ent2 : Entity_Id;
2692 Kind1, Kind2 : Character;
2693 Cons1, Cons2 : Uint;
2695 -- Start of processing for Extract_Length
2699 (Original_Node (Type_Low_Bound (T)), Ent1, Kind1, Cons1);
2701 (Original_Node (Type_High_Bound (T)), Ent2, Kind2, Cons2);
2704 and then Kind1 = Kind2
2705 and then Ent1 = Ent2
2707 Len := Cons2 - Cons1 + 1;
2709 Len := Uint_Minus_1;
2712 end Get_Static_Length;
2719 -- Start of processing for Length_Mismatch
2722 Get_Static_Length (Left, Len_L);
2723 Get_Static_Length (Right, Len_R);
2725 if Len_L /= Uint_Minus_1
2726 and then Len_R /= Uint_Minus_1
2727 and then Len_L /= Len_R
2729 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2730 Warn_On_Known_Condition (N);
2733 end Length_Mismatch;
2736 -- Test for expression being foldable
2738 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2740 -- Only comparisons of scalars can give static results. In particular,
2741 -- comparisons of strings never yield a static result, even if both
2742 -- operands are static strings.
2744 if not Is_Scalar_Type (Typ) then
2746 Set_Is_Static_Expression (N, False);
2749 -- For static real type expressions, we cannot use Compile_Time_Compare
2750 -- since it worries about run-time results which are not exact.
2752 if Stat and then Is_Real_Type (Typ) then
2754 Left_Real : constant Ureal := Expr_Value_R (Left);
2755 Right_Real : constant Ureal := Expr_Value_R (Right);
2759 when N_Op_Eq => Result := (Left_Real = Right_Real);
2760 when N_Op_Ne => Result := (Left_Real /= Right_Real);
2761 when N_Op_Lt => Result := (Left_Real < Right_Real);
2762 when N_Op_Le => Result := (Left_Real <= Right_Real);
2763 when N_Op_Gt => Result := (Left_Real > Right_Real);
2764 when N_Op_Ge => Result := (Left_Real >= Right_Real);
2767 raise Program_Error;
2770 Fold_Uint (N, Test (Result), True);
2773 -- For all other cases, we use Compile_Time_Compare to do the compare
2777 CR : constant Compare_Result :=
2778 Compile_Time_Compare (Left, Right, Assume_Valid => False);
2781 if CR = Unknown then
2789 elsif CR = NE or else CR = GT or else CR = LT then
2796 if CR = NE or else CR = GT or else CR = LT then
2807 elsif CR = EQ or else CR = GT or else CR = GE then
2814 if CR = LT or else CR = EQ or else CR = LE then
2825 elsif CR = EQ or else CR = LT or else CR = LE then
2832 if CR = GT or else CR = EQ or else CR = GE then
2841 raise Program_Error;
2845 Fold_Uint (N, Test (Result), Stat);
2848 Warn_On_Known_Condition (N);
2849 end Eval_Relational_Op;
2855 -- Shift operations are intrinsic operations that can never be static,
2856 -- so the only processing required is to perform the required check for
2857 -- a non static context for the two operands.
2859 -- Actually we could do some compile time evaluation here some time ???
2861 procedure Eval_Shift (N : Node_Id) is
2863 Check_Non_Static_Context (Left_Opnd (N));
2864 Check_Non_Static_Context (Right_Opnd (N));
2867 ------------------------
2868 -- Eval_Short_Circuit --
2869 ------------------------
2871 -- A short circuit operation is potentially static if both operands
2872 -- are potentially static (RM 4.9 (13))
2874 procedure Eval_Short_Circuit (N : Node_Id) is
2875 Kind : constant Node_Kind := Nkind (N);
2876 Left : constant Node_Id := Left_Opnd (N);
2877 Right : constant Node_Id := Right_Opnd (N);
2879 Rstat : constant Boolean :=
2880 Is_Static_Expression (Left)
2881 and then Is_Static_Expression (Right);
2884 -- Short circuit operations are never static in Ada 83
2886 if Ada_Version = Ada_83
2887 and then Comes_From_Source (N)
2889 Check_Non_Static_Context (Left);
2890 Check_Non_Static_Context (Right);
2894 -- Now look at the operands, we can't quite use the normal call to
2895 -- Test_Expression_Is_Foldable here because short circuit operations
2896 -- are a special case, they can still be foldable, even if the right
2897 -- operand raises constraint error.
2899 -- If either operand is Any_Type, just propagate to result and
2900 -- do not try to fold, this prevents cascaded errors.
2902 if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
2903 Set_Etype (N, Any_Type);
2906 -- If left operand raises constraint error, then replace node N with
2907 -- the raise constraint error node, and we are obviously not foldable.
2908 -- Is_Static_Expression is set from the two operands in the normal way,
2909 -- and we check the right operand if it is in a non-static context.
2911 elsif Raises_Constraint_Error (Left) then
2913 Check_Non_Static_Context (Right);
2916 Rewrite_In_Raise_CE (N, Left);
2917 Set_Is_Static_Expression (N, Rstat);
2920 -- If the result is not static, then we won't in any case fold
2922 elsif not Rstat then
2923 Check_Non_Static_Context (Left);
2924 Check_Non_Static_Context (Right);
2928 -- Here the result is static, note that, unlike the normal processing
2929 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
2930 -- the right operand raises constraint error, that's because it is not
2931 -- significant if the left operand is decisive.
2933 Set_Is_Static_Expression (N);
2935 -- It does not matter if the right operand raises constraint error if
2936 -- it will not be evaluated. So deal specially with the cases where
2937 -- the right operand is not evaluated. Note that we will fold these
2938 -- cases even if the right operand is non-static, which is fine, but
2939 -- of course in these cases the result is not potentially static.
2941 Left_Int := Expr_Value (Left);
2943 if (Kind = N_And_Then and then Is_False (Left_Int))
2945 (Kind = N_Or_Else and then Is_True (Left_Int))
2947 Fold_Uint (N, Left_Int, Rstat);
2951 -- If first operand not decisive, then it does matter if the right
2952 -- operand raises constraint error, since it will be evaluated, so
2953 -- we simply replace the node with the right operand. Note that this
2954 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
2955 -- (both are set to True in Right).
2957 if Raises_Constraint_Error (Right) then
2958 Rewrite_In_Raise_CE (N, Right);
2959 Check_Non_Static_Context (Left);
2963 -- Otherwise the result depends on the right operand
2965 Fold_Uint (N, Expr_Value (Right), Rstat);
2967 end Eval_Short_Circuit;
2973 -- Slices can never be static, so the only processing required is to
2974 -- check for non-static context if an explicit range is given.
2976 procedure Eval_Slice (N : Node_Id) is
2977 Drange : constant Node_Id := Discrete_Range (N);
2979 if Nkind (Drange) = N_Range then
2980 Check_Non_Static_Context (Low_Bound (Drange));
2981 Check_Non_Static_Context (High_Bound (Drange));
2984 -- A slice of the form A (subtype), when the subtype is the index of
2985 -- the type of A, is redundant, the slice can be replaced with A, and
2986 -- this is worth a warning.
2988 if Is_Entity_Name (Prefix (N)) then
2990 E : constant Entity_Id := Entity (Prefix (N));
2991 T : constant Entity_Id := Etype (E);
2993 if Ekind (E) = E_Constant
2994 and then Is_Array_Type (T)
2995 and then Is_Entity_Name (Drange)
2997 if Is_Entity_Name (Original_Node (First_Index (T)))
2998 and then Entity (Original_Node (First_Index (T)))
3001 if Warn_On_Redundant_Constructs then
3002 Error_Msg_N ("redundant slice denotes whole array?", N);
3005 -- The following might be a useful optimization ????
3007 -- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
3014 -------------------------
3015 -- Eval_String_Literal --
3016 -------------------------
3018 procedure Eval_String_Literal (N : Node_Id) is
3019 Typ : constant Entity_Id := Etype (N);
3020 Bas : constant Entity_Id := Base_Type (Typ);
3026 -- Nothing to do if error type (handles cases like default expressions
3027 -- or generics where we have not yet fully resolved the type)
3029 if Bas = Any_Type or else Bas = Any_String then
3033 -- String literals are static if the subtype is static (RM 4.9(2)), so
3034 -- reset the static expression flag (it was set unconditionally in
3035 -- Analyze_String_Literal) if the subtype is non-static. We tell if
3036 -- the subtype is static by looking at the lower bound.
3038 if Ekind (Typ) = E_String_Literal_Subtype then
3039 if not Is_OK_Static_Expression (String_Literal_Low_Bound (Typ)) then
3040 Set_Is_Static_Expression (N, False);
3044 -- Here if Etype of string literal is normal Etype (not yet possible,
3045 -- but may be possible in future!)
3047 elsif not Is_OK_Static_Expression
3048 (Type_Low_Bound (Etype (First_Index (Typ))))
3050 Set_Is_Static_Expression (N, False);
3054 -- If original node was a type conversion, then result if non-static
3056 if Nkind (Original_Node (N)) = N_Type_Conversion then
3057 Set_Is_Static_Expression (N, False);
3061 -- Test for illegal Ada 95 cases. A string literal is illegal in
3062 -- Ada 95 if its bounds are outside the index base type and this
3063 -- index type is static. This can happen in only two ways. Either
3064 -- the string literal is too long, or it is null, and the lower
3065 -- bound is type'First. In either case it is the upper bound that
3066 -- is out of range of the index type.
3068 if Ada_Version >= Ada_95 then
3069 if Root_Type (Bas) = Standard_String
3071 Root_Type (Bas) = Standard_Wide_String
3073 Xtp := Standard_Positive;
3075 Xtp := Etype (First_Index (Bas));
3078 if Ekind (Typ) = E_String_Literal_Subtype then
3079 Lo := String_Literal_Low_Bound (Typ);
3081 Lo := Type_Low_Bound (Etype (First_Index (Typ)));
3084 Len := String_Length (Strval (N));
3086 if UI_From_Int (Len) > String_Type_Len (Bas) then
3087 Apply_Compile_Time_Constraint_Error
3088 (N, "string literal too long for}", CE_Length_Check_Failed,
3090 Typ => First_Subtype (Bas));
3093 and then not Is_Generic_Type (Xtp)
3095 Expr_Value (Lo) = Expr_Value (Type_Low_Bound (Base_Type (Xtp)))
3097 Apply_Compile_Time_Constraint_Error
3098 (N, "null string literal not allowed for}",
3099 CE_Length_Check_Failed,
3101 Typ => First_Subtype (Bas));
3104 end Eval_String_Literal;
3106 --------------------------
3107 -- Eval_Type_Conversion --
3108 --------------------------
3110 -- A type conversion is potentially static if its subtype mark is for a
3111 -- static scalar subtype, and its operand expression is potentially static
3114 procedure Eval_Type_Conversion (N : Node_Id) is
3115 Operand : constant Node_Id := Expression (N);
3116 Source_Type : constant Entity_Id := Etype (Operand);
3117 Target_Type : constant Entity_Id := Etype (N);
3122 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean;
3123 -- Returns true if type T is an integer type, or if it is a
3124 -- fixed-point type to be treated as an integer (i.e. the flag
3125 -- Conversion_OK is set on the conversion node).
3127 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean;
3128 -- Returns true if type T is a floating-point type, or if it is a
3129 -- fixed-point type that is not to be treated as an integer (i.e. the
3130 -- flag Conversion_OK is not set on the conversion node).
3132 ------------------------------
3133 -- To_Be_Treated_As_Integer --
3134 ------------------------------
3136 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean is
3140 or else (Is_Fixed_Point_Type (T) and then Conversion_OK (N));
3141 end To_Be_Treated_As_Integer;
3143 ---------------------------
3144 -- To_Be_Treated_As_Real --
3145 ---------------------------
3147 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean is
3150 Is_Floating_Point_Type (T)
3151 or else (Is_Fixed_Point_Type (T) and then not Conversion_OK (N));
3152 end To_Be_Treated_As_Real;
3154 -- Start of processing for Eval_Type_Conversion
3157 -- Cannot fold if target type is non-static or if semantic error
3159 if not Is_Static_Subtype (Target_Type) then
3160 Check_Non_Static_Context (Operand);
3163 elsif Error_Posted (N) then
3167 -- If not foldable we are done
3169 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
3174 -- Don't try fold if target type has constraint error bounds
3176 elsif not Is_OK_Static_Subtype (Target_Type) then
3177 Set_Raises_Constraint_Error (N);
3181 -- Remaining processing depends on operand types. Note that in the
3182 -- following type test, fixed-point counts as real unless the flag
3183 -- Conversion_OK is set, in which case it counts as integer.
3185 -- Fold conversion, case of string type. The result is not static
3187 if Is_String_Type (Target_Type) then
3188 Fold_Str (N, Strval (Get_String_Val (Operand)), Static => False);
3192 -- Fold conversion, case of integer target type
3194 elsif To_Be_Treated_As_Integer (Target_Type) then
3199 -- Integer to integer conversion
3201 if To_Be_Treated_As_Integer (Source_Type) then
3202 Result := Expr_Value (Operand);
3204 -- Real to integer conversion
3207 Result := UR_To_Uint (Expr_Value_R (Operand));
3210 -- If fixed-point type (Conversion_OK must be set), then the
3211 -- result is logically an integer, but we must replace the
3212 -- conversion with the corresponding real literal, since the
3213 -- type from a semantic point of view is still fixed-point.
3215 if Is_Fixed_Point_Type (Target_Type) then
3217 (N, UR_From_Uint (Result) * Small_Value (Target_Type), Stat);
3219 -- Otherwise result is integer literal
3222 Fold_Uint (N, Result, Stat);
3226 -- Fold conversion, case of real target type
3228 elsif To_Be_Treated_As_Real (Target_Type) then
3233 if To_Be_Treated_As_Real (Source_Type) then
3234 Result := Expr_Value_R (Operand);
3236 Result := UR_From_Uint (Expr_Value (Operand));
3239 Fold_Ureal (N, Result, Stat);
3242 -- Enumeration types
3245 Fold_Uint (N, Expr_Value (Operand), Stat);
3248 if Is_Out_Of_Range (N, Etype (N), Assume_Valid => True) then
3252 end Eval_Type_Conversion;
3258 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
3259 -- are potentially static if the operand is potentially static (RM 4.9(7))
3261 procedure Eval_Unary_Op (N : Node_Id) is
3262 Right : constant Node_Id := Right_Opnd (N);
3267 -- If not foldable we are done
3269 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
3275 -- Fold for integer case
3277 if Is_Integer_Type (Etype (N)) then
3279 Rint : constant Uint := Expr_Value (Right);
3283 -- In the case of modular unary plus and abs there is no need
3284 -- to adjust the result of the operation since if the original
3285 -- operand was in bounds the result will be in the bounds of the
3286 -- modular type. However, in the case of modular unary minus the
3287 -- result may go out of the bounds of the modular type and needs
3290 if Nkind (N) = N_Op_Plus then
3293 elsif Nkind (N) = N_Op_Minus then
3294 if Is_Modular_Integer_Type (Etype (N)) then
3295 Result := (-Rint) mod Modulus (Etype (N));
3301 pragma Assert (Nkind (N) = N_Op_Abs);
3305 Fold_Uint (N, Result, Stat);
3308 -- Fold for real case
3310 elsif Is_Real_Type (Etype (N)) then
3312 Rreal : constant Ureal := Expr_Value_R (Right);
3316 if Nkind (N) = N_Op_Plus then
3319 elsif Nkind (N) = N_Op_Minus then
3320 Result := UR_Negate (Rreal);
3323 pragma Assert (Nkind (N) = N_Op_Abs);
3324 Result := abs Rreal;
3327 Fold_Ureal (N, Result, Stat);
3332 -------------------------------
3333 -- Eval_Unchecked_Conversion --
3334 -------------------------------
3336 -- Unchecked conversions can never be static, so the only required
3337 -- processing is to check for a non-static context for the operand.
3339 procedure Eval_Unchecked_Conversion (N : Node_Id) is
3341 Check_Non_Static_Context (Expression (N));
3342 end Eval_Unchecked_Conversion;
3344 --------------------
3345 -- Expr_Rep_Value --
3346 --------------------
3348 function Expr_Rep_Value (N : Node_Id) return Uint is
3349 Kind : constant Node_Kind := Nkind (N);
3353 if Is_Entity_Name (N) then
3356 -- An enumeration literal that was either in the source or
3357 -- created as a result of static evaluation.
3359 if Ekind (Ent) = E_Enumeration_Literal then
3360 return Enumeration_Rep (Ent);
3362 -- A user defined static constant
3365 pragma Assert (Ekind (Ent) = E_Constant);
3366 return Expr_Rep_Value (Constant_Value (Ent));
3369 -- An integer literal that was either in the source or created
3370 -- as a result of static evaluation.
3372 elsif Kind = N_Integer_Literal then
3375 -- A real literal for a fixed-point type. This must be the fixed-point
3376 -- case, either the literal is of a fixed-point type, or it is a bound
3377 -- of a fixed-point type, with type universal real. In either case we
3378 -- obtain the desired value from Corresponding_Integer_Value.
3380 elsif Kind = N_Real_Literal then
3381 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
3382 return Corresponding_Integer_Value (N);
3384 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3386 elsif Kind = N_Attribute_Reference
3387 and then Attribute_Name (N) = Name_Null_Parameter
3391 -- Otherwise must be character literal
3394 pragma Assert (Kind = N_Character_Literal);
3397 -- Since Character literals of type Standard.Character don't
3398 -- have any defining character literals built for them, they
3399 -- do not have their Entity set, so just use their Char
3400 -- code. Otherwise for user-defined character literals use
3401 -- their Pos value as usual which is the same as the Rep value.
3404 return Char_Literal_Value (N);
3406 return Enumeration_Rep (Ent);
3415 function Expr_Value (N : Node_Id) return Uint is
3416 Kind : constant Node_Kind := Nkind (N);
3417 CV_Ent : CV_Entry renames CV_Cache (Nat (N) mod CV_Cache_Size);
3422 -- If already in cache, then we know it's compile time known and we can
3423 -- return the value that was previously stored in the cache since
3424 -- compile time known values cannot change.
3426 if CV_Ent.N = N then
3430 -- Otherwise proceed to test value
3432 if Is_Entity_Name (N) then
3435 -- An enumeration literal that was either in the source or
3436 -- created as a result of static evaluation.
3438 if Ekind (Ent) = E_Enumeration_Literal then
3439 Val := Enumeration_Pos (Ent);
3441 -- A user defined static constant
3444 pragma Assert (Ekind (Ent) = E_Constant);
3445 Val := Expr_Value (Constant_Value (Ent));
3448 -- An integer literal that was either in the source or created
3449 -- as a result of static evaluation.
3451 elsif Kind = N_Integer_Literal then
3454 -- A real literal for a fixed-point type. This must be the fixed-point
3455 -- case, either the literal is of a fixed-point type, or it is a bound
3456 -- of a fixed-point type, with type universal real. In either case we
3457 -- obtain the desired value from Corresponding_Integer_Value.
3459 elsif Kind = N_Real_Literal then
3461 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
3462 Val := Corresponding_Integer_Value (N);
3464 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3466 elsif Kind = N_Attribute_Reference
3467 and then Attribute_Name (N) = Name_Null_Parameter
3471 -- Otherwise must be character literal
3474 pragma Assert (Kind = N_Character_Literal);
3477 -- Since Character literals of type Standard.Character don't
3478 -- have any defining character literals built for them, they
3479 -- do not have their Entity set, so just use their Char
3480 -- code. Otherwise for user-defined character literals use
3481 -- their Pos value as usual.
3484 Val := Char_Literal_Value (N);
3486 Val := Enumeration_Pos (Ent);
3490 -- Come here with Val set to value to be returned, set cache
3501 function Expr_Value_E (N : Node_Id) return Entity_Id is
3502 Ent : constant Entity_Id := Entity (N);
3505 if Ekind (Ent) = E_Enumeration_Literal then
3508 pragma Assert (Ekind (Ent) = E_Constant);
3509 return Expr_Value_E (Constant_Value (Ent));
3517 function Expr_Value_R (N : Node_Id) return Ureal is
3518 Kind : constant Node_Kind := Nkind (N);
3523 if Kind = N_Real_Literal then
3526 elsif Kind = N_Identifier or else Kind = N_Expanded_Name then
3528 pragma Assert (Ekind (Ent) = E_Constant);
3529 return Expr_Value_R (Constant_Value (Ent));
3531 elsif Kind = N_Integer_Literal then
3532 return UR_From_Uint (Expr_Value (N));
3534 -- Strange case of VAX literals, which are at this stage transformed
3535 -- into Vax_Type!x_To_y(IEEE_Literal). See Expand_N_Real_Literal in
3536 -- Exp_Vfpt for further details.
3538 elsif Vax_Float (Etype (N))
3539 and then Nkind (N) = N_Unchecked_Type_Conversion
3541 Expr := Expression (N);
3543 if Nkind (Expr) = N_Function_Call
3544 and then Present (Parameter_Associations (Expr))
3546 Expr := First (Parameter_Associations (Expr));
3548 if Nkind (Expr) = N_Real_Literal then
3549 return Realval (Expr);
3553 -- Peculiar VMS case, if we have xxx'Null_Parameter, return 0.0
3555 elsif Kind = N_Attribute_Reference
3556 and then Attribute_Name (N) = Name_Null_Parameter
3561 -- If we fall through, we have a node that cannot be interpreted
3562 -- as a compile time constant. That is definitely an error.
3564 raise Program_Error;
3571 function Expr_Value_S (N : Node_Id) return Node_Id is
3573 if Nkind (N) = N_String_Literal then
3576 pragma Assert (Ekind (Entity (N)) = E_Constant);
3577 return Expr_Value_S (Constant_Value (Entity (N)));
3581 --------------------------
3582 -- Flag_Non_Static_Expr --
3583 --------------------------
3585 procedure Flag_Non_Static_Expr (Msg : String; Expr : Node_Id) is
3587 if Error_Posted (Expr) and then not All_Errors_Mode then
3590 Error_Msg_F (Msg, Expr);
3591 Why_Not_Static (Expr);
3593 end Flag_Non_Static_Expr;
3599 procedure Fold_Str (N : Node_Id; Val : String_Id; Static : Boolean) is
3600 Loc : constant Source_Ptr := Sloc (N);
3601 Typ : constant Entity_Id := Etype (N);
3604 Rewrite (N, Make_String_Literal (Loc, Strval => Val));
3606 -- We now have the literal with the right value, both the actual type
3607 -- and the expected type of this literal are taken from the expression
3608 -- that was evaluated.
3611 Set_Is_Static_Expression (N, Static);
3620 procedure Fold_Uint (N : Node_Id; Val : Uint; Static : Boolean) is
3621 Loc : constant Source_Ptr := Sloc (N);
3622 Typ : Entity_Id := Etype (N);
3626 -- If we are folding a named number, retain the entity in the
3627 -- literal, for ASIS use.
3629 if Is_Entity_Name (N)
3630 and then Ekind (Entity (N)) = E_Named_Integer
3637 if Is_Private_Type (Typ) then
3638 Typ := Full_View (Typ);
3641 -- For a result of type integer, substitute an N_Integer_Literal node
3642 -- for the result of the compile time evaluation of the expression.
3643 -- For ASIS use, set a link to the original named number when not in
3644 -- a generic context.
3646 if Is_Integer_Type (Typ) then
3647 Rewrite (N, Make_Integer_Literal (Loc, Val));
3649 Set_Original_Entity (N, Ent);
3651 -- Otherwise we have an enumeration type, and we substitute either
3652 -- an N_Identifier or N_Character_Literal to represent the enumeration
3653 -- literal corresponding to the given value, which must always be in
3654 -- range, because appropriate tests have already been made for this.
3656 else pragma Assert (Is_Enumeration_Type (Typ));
3657 Rewrite (N, Get_Enum_Lit_From_Pos (Etype (N), Val, Loc));
3660 -- We now have the literal with the right value, both the actual type
3661 -- and the expected type of this literal are taken from the expression
3662 -- that was evaluated.
3665 Set_Is_Static_Expression (N, Static);
3674 procedure Fold_Ureal (N : Node_Id; Val : Ureal; Static : Boolean) is
3675 Loc : constant Source_Ptr := Sloc (N);
3676 Typ : constant Entity_Id := Etype (N);
3680 -- If we are folding a named number, retain the entity in the
3681 -- literal, for ASIS use.
3683 if Is_Entity_Name (N)
3684 and then Ekind (Entity (N)) = E_Named_Real
3691 Rewrite (N, Make_Real_Literal (Loc, Realval => Val));
3693 -- Set link to original named number, for ASIS use
3695 Set_Original_Entity (N, Ent);
3697 -- Both the actual and expected type comes from the original expression
3700 Set_Is_Static_Expression (N, Static);
3709 function From_Bits (B : Bits; T : Entity_Id) return Uint is
3713 for J in 0 .. B'Last loop
3719 if Non_Binary_Modulus (T) then
3720 V := V mod Modulus (T);
3726 --------------------
3727 -- Get_String_Val --
3728 --------------------
3730 function Get_String_Val (N : Node_Id) return Node_Id is
3732 if Nkind (N) = N_String_Literal then
3735 elsif Nkind (N) = N_Character_Literal then
3739 pragma Assert (Is_Entity_Name (N));
3740 return Get_String_Val (Constant_Value (Entity (N)));
3748 procedure Initialize is
3750 CV_Cache := (others => (Node_High_Bound, Uint_0));
3753 --------------------
3754 -- In_Subrange_Of --
3755 --------------------
3757 function In_Subrange_Of
3760 Fixed_Int : Boolean := False) return Boolean
3769 if T1 = T2 or else Is_Subtype_Of (T1, T2) then
3772 -- Never in range if both types are not scalar. Don't know if this can
3773 -- actually happen, but just in case.
3775 elsif not Is_Scalar_Type (T1) or else not Is_Scalar_Type (T1) then
3778 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
3779 -- definitely not compatible with T2.
3781 elsif Is_Floating_Point_Type (T1)
3782 and then Has_Infinities (T1)
3783 and then Is_Floating_Point_Type (T2)
3784 and then not Has_Infinities (T2)
3789 L1 := Type_Low_Bound (T1);
3790 H1 := Type_High_Bound (T1);
3792 L2 := Type_Low_Bound (T2);
3793 H2 := Type_High_Bound (T2);
3795 -- Check bounds to see if comparison possible at compile time
3797 if Compile_Time_Compare (L1, L2, Assume_Valid => True) in Compare_GE
3799 Compile_Time_Compare (H1, H2, Assume_Valid => True) in Compare_LE
3804 -- If bounds not comparable at compile time, then the bounds of T2
3805 -- must be compile time known or we cannot answer the query.
3807 if not Compile_Time_Known_Value (L2)
3808 or else not Compile_Time_Known_Value (H2)
3813 -- If the bounds of T1 are know at compile time then use these
3814 -- ones, otherwise use the bounds of the base type (which are of
3815 -- course always static).
3817 if not Compile_Time_Known_Value (L1) then
3818 L1 := Type_Low_Bound (Base_Type (T1));
3821 if not Compile_Time_Known_Value (H1) then
3822 H1 := Type_High_Bound (Base_Type (T1));
3825 -- Fixed point types should be considered as such only if
3826 -- flag Fixed_Int is set to False.
3828 if Is_Floating_Point_Type (T1) or else Is_Floating_Point_Type (T2)
3829 or else (Is_Fixed_Point_Type (T1) and then not Fixed_Int)
3830 or else (Is_Fixed_Point_Type (T2) and then not Fixed_Int)
3833 Expr_Value_R (L2) <= Expr_Value_R (L1)
3835 Expr_Value_R (H2) >= Expr_Value_R (H1);
3839 Expr_Value (L2) <= Expr_Value (L1)
3841 Expr_Value (H2) >= Expr_Value (H1);
3846 -- If any exception occurs, it means that we have some bug in the compiler
3847 -- possibly triggered by a previous error, or by some unforeseen peculiar
3848 -- occurrence. However, this is only an optimization attempt, so there is
3849 -- really no point in crashing the compiler. Instead we just decide, too
3850 -- bad, we can't figure out the answer in this case after all.
3855 -- Debug flag K disables this behavior (useful for debugging)
3857 if Debug_Flag_K then
3868 function Is_In_Range
3871 Assume_Valid : Boolean := False;
3872 Fixed_Int : Boolean := False;
3873 Int_Real : Boolean := False) return Boolean
3878 pragma Warnings (Off, Assume_Valid);
3879 -- For now Assume_Valid is unreferenced since the current implementation
3880 -- always returns False if N is not a compile time known value, but we
3881 -- keep the parameter to allow for future enhancements in which we try
3882 -- to get the information in the variable case as well.
3885 -- Universal types have no range limits, so always in range
3887 if Typ = Universal_Integer or else Typ = Universal_Real then
3890 -- Never in range if not scalar type. Don't know if this can
3891 -- actually happen, but our spec allows it, so we must check!
3893 elsif not Is_Scalar_Type (Typ) then
3896 -- Never in range unless we have a compile time known value
3898 elsif not Compile_Time_Known_Value (N) then
3901 -- General processing with a known compile time value
3911 Lo := Type_Low_Bound (Typ);
3912 Hi := Type_High_Bound (Typ);
3914 LB_Known := Compile_Time_Known_Value (Lo);
3915 UB_Known := Compile_Time_Known_Value (Hi);
3917 -- Fixed point types should be considered as such only in
3918 -- flag Fixed_Int is set to False.
3920 if Is_Floating_Point_Type (Typ)
3921 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
3924 Valr := Expr_Value_R (N);
3926 if LB_Known and then Valr >= Expr_Value_R (Lo)
3927 and then UB_Known and then Valr <= Expr_Value_R (Hi)
3935 Val := Expr_Value (N);
3937 if LB_Known and then Val >= Expr_Value (Lo)
3938 and then UB_Known and then Val <= Expr_Value (Hi)
3953 function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
3954 Typ : constant Entity_Id := Etype (Lo);
3957 if not Compile_Time_Known_Value (Lo)
3958 or else not Compile_Time_Known_Value (Hi)
3963 if Is_Discrete_Type (Typ) then
3964 return Expr_Value (Lo) > Expr_Value (Hi);
3967 pragma Assert (Is_Real_Type (Typ));
3968 return Expr_Value_R (Lo) > Expr_Value_R (Hi);
3972 -----------------------------
3973 -- Is_OK_Static_Expression --
3974 -----------------------------
3976 function Is_OK_Static_Expression (N : Node_Id) return Boolean is
3978 return Is_Static_Expression (N)
3979 and then not Raises_Constraint_Error (N);
3980 end Is_OK_Static_Expression;
3982 ------------------------
3983 -- Is_OK_Static_Range --
3984 ------------------------
3986 -- A static range is a range whose bounds are static expressions, or a
3987 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
3988 -- We have already converted range attribute references, so we get the
3989 -- "or" part of this rule without needing a special test.
3991 function Is_OK_Static_Range (N : Node_Id) return Boolean is
3993 return Is_OK_Static_Expression (Low_Bound (N))
3994 and then Is_OK_Static_Expression (High_Bound (N));
3995 end Is_OK_Static_Range;
3997 --------------------------
3998 -- Is_OK_Static_Subtype --
3999 --------------------------
4001 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
4002 -- where neither bound raises constraint error when evaluated.
4004 function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean is
4005 Base_T : constant Entity_Id := Base_Type (Typ);
4006 Anc_Subt : Entity_Id;
4009 -- First a quick check on the non static subtype flag. As described
4010 -- in further detail in Einfo, this flag is not decisive in all cases,
4011 -- but if it is set, then the subtype is definitely non-static.
4013 if Is_Non_Static_Subtype (Typ) then
4017 Anc_Subt := Ancestor_Subtype (Typ);
4019 if Anc_Subt = Empty then
4023 if Is_Generic_Type (Root_Type (Base_T))
4024 or else Is_Generic_Actual_Type (Base_T)
4030 elsif Is_String_Type (Typ) then
4032 Ekind (Typ) = E_String_Literal_Subtype
4034 (Is_OK_Static_Subtype (Component_Type (Typ))
4035 and then Is_OK_Static_Subtype (Etype (First_Index (Typ))));
4039 elsif Is_Scalar_Type (Typ) then
4040 if Base_T = Typ then
4044 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so
4045 -- use Get_Type_Low,High_Bound.
4047 return Is_OK_Static_Subtype (Anc_Subt)
4048 and then Is_OK_Static_Expression (Type_Low_Bound (Typ))
4049 and then Is_OK_Static_Expression (Type_High_Bound (Typ));
4052 -- Types other than string and scalar types are never static
4057 end Is_OK_Static_Subtype;
4059 ---------------------
4060 -- Is_Out_Of_Range --
4061 ---------------------
4063 function Is_Out_Of_Range
4066 Assume_Valid : Boolean := False;
4067 Fixed_Int : Boolean := False;
4068 Int_Real : Boolean := False) return Boolean
4073 pragma Warnings (Off, Assume_Valid);
4074 -- For now Assume_Valid is unreferenced since the current implementation
4075 -- always returns False if N is not a compile time known value, but we
4076 -- keep the parameter to allow for future enhancements in which we try
4077 -- to get the information in the variable case as well.
4080 -- Universal types have no range limits, so always in range
4082 if Typ = Universal_Integer or else Typ = Universal_Real then
4085 -- Never out of range if not scalar type. Don't know if this can
4086 -- actually happen, but our spec allows it, so we must check!
4088 elsif not Is_Scalar_Type (Typ) then
4091 -- Never out of range if this is a generic type, since the bounds
4092 -- of generic types are junk. Note that if we only checked for
4093 -- static expressions (instead of compile time known values) below,
4094 -- we would not need this check, because values of a generic type
4095 -- can never be static, but they can be known at compile time.
4097 elsif Is_Generic_Type (Typ) then
4100 -- Never out of range unless we have a compile time known value
4102 elsif not Compile_Time_Known_Value (N) then
4113 Lo := Type_Low_Bound (Typ);
4114 Hi := Type_High_Bound (Typ);
4116 LB_Known := Compile_Time_Known_Value (Lo);
4117 UB_Known := Compile_Time_Known_Value (Hi);
4119 -- Real types (note that fixed-point types are not treated
4120 -- as being of a real type if the flag Fixed_Int is set,
4121 -- since in that case they are regarded as integer types).
4123 if Is_Floating_Point_Type (Typ)
4124 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
4127 Valr := Expr_Value_R (N);
4129 if LB_Known and then Valr < Expr_Value_R (Lo) then
4132 elsif UB_Known and then Expr_Value_R (Hi) < Valr then
4140 Val := Expr_Value (N);
4142 if LB_Known and then Val < Expr_Value (Lo) then
4145 elsif UB_Known and then Expr_Value (Hi) < Val then
4154 end Is_Out_Of_Range;
4156 ---------------------
4157 -- Is_Static_Range --
4158 ---------------------
4160 -- A static range is a range whose bounds are static expressions, or a
4161 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4162 -- We have already converted range attribute references, so we get the
4163 -- "or" part of this rule without needing a special test.
4165 function Is_Static_Range (N : Node_Id) return Boolean is
4167 return Is_Static_Expression (Low_Bound (N))
4168 and then Is_Static_Expression (High_Bound (N));
4169 end Is_Static_Range;
4171 -----------------------
4172 -- Is_Static_Subtype --
4173 -----------------------
4175 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
4177 function Is_Static_Subtype (Typ : Entity_Id) return Boolean is
4178 Base_T : constant Entity_Id := Base_Type (Typ);
4179 Anc_Subt : Entity_Id;
4182 -- First a quick check on the non static subtype flag. As described
4183 -- in further detail in Einfo, this flag is not decisive in all cases,
4184 -- but if it is set, then the subtype is definitely non-static.
4186 if Is_Non_Static_Subtype (Typ) then
4190 Anc_Subt := Ancestor_Subtype (Typ);
4192 if Anc_Subt = Empty then
4196 if Is_Generic_Type (Root_Type (Base_T))
4197 or else Is_Generic_Actual_Type (Base_T)
4203 elsif Is_String_Type (Typ) then
4205 Ekind (Typ) = E_String_Literal_Subtype
4207 (Is_Static_Subtype (Component_Type (Typ))
4208 and then Is_Static_Subtype (Etype (First_Index (Typ))));
4212 elsif Is_Scalar_Type (Typ) then
4213 if Base_T = Typ then
4217 return Is_Static_Subtype (Anc_Subt)
4218 and then Is_Static_Expression (Type_Low_Bound (Typ))
4219 and then Is_Static_Expression (Type_High_Bound (Typ));
4222 -- Types other than string and scalar types are never static
4227 end Is_Static_Subtype;
4229 --------------------
4230 -- Not_Null_Range --
4231 --------------------
4233 function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
4234 Typ : constant Entity_Id := Etype (Lo);
4237 if not Compile_Time_Known_Value (Lo)
4238 or else not Compile_Time_Known_Value (Hi)
4243 if Is_Discrete_Type (Typ) then
4244 return Expr_Value (Lo) <= Expr_Value (Hi);
4247 pragma Assert (Is_Real_Type (Typ));
4249 return Expr_Value_R (Lo) <= Expr_Value_R (Hi);
4257 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean is
4259 -- We allow a maximum of 500,000 bits which seems a reasonable limit
4261 if Bits < 500_000 then
4265 Error_Msg_N ("static value too large, capacity exceeded", N);
4274 procedure Out_Of_Range (N : Node_Id) is
4276 -- If we have the static expression case, then this is an illegality
4277 -- in Ada 95 mode, except that in an instance, we never generate an
4278 -- error (if the error is legitimate, it was already diagnosed in
4279 -- the template). The expression to compute the length of a packed
4280 -- array is attached to the array type itself, and deserves a separate
4283 if Is_Static_Expression (N)
4284 and then not In_Instance
4285 and then not In_Inlined_Body
4286 and then Ada_Version >= Ada_95
4288 if Nkind (Parent (N)) = N_Defining_Identifier
4289 and then Is_Array_Type (Parent (N))
4290 and then Present (Packed_Array_Type (Parent (N)))
4291 and then Present (First_Rep_Item (Parent (N)))
4294 ("length of packed array must not exceed Integer''Last",
4295 First_Rep_Item (Parent (N)));
4296 Rewrite (N, Make_Integer_Literal (Sloc (N), Uint_1));
4299 Apply_Compile_Time_Constraint_Error
4300 (N, "value not in range of}", CE_Range_Check_Failed);
4303 -- Here we generate a warning for the Ada 83 case, or when we are
4304 -- in an instance, or when we have a non-static expression case.
4307 Apply_Compile_Time_Constraint_Error
4308 (N, "value not in range of}?", CE_Range_Check_Failed);
4312 -------------------------
4313 -- Rewrite_In_Raise_CE --
4314 -------------------------
4316 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id) is
4317 Typ : constant Entity_Id := Etype (N);
4320 -- If we want to raise CE in the condition of a raise_CE node
4321 -- we may as well get rid of the condition
4323 if Present (Parent (N))
4324 and then Nkind (Parent (N)) = N_Raise_Constraint_Error
4326 Set_Condition (Parent (N), Empty);
4328 -- If the expression raising CE is a N_Raise_CE node, we can use
4329 -- that one. We just preserve the type of the context
4331 elsif Nkind (Exp) = N_Raise_Constraint_Error then
4335 -- We have to build an explicit raise_ce node
4339 Make_Raise_Constraint_Error (Sloc (Exp),
4340 Reason => CE_Range_Check_Failed));
4341 Set_Raises_Constraint_Error (N);
4344 end Rewrite_In_Raise_CE;
4346 ---------------------
4347 -- String_Type_Len --
4348 ---------------------
4350 function String_Type_Len (Stype : Entity_Id) return Uint is
4351 NT : constant Entity_Id := Etype (First_Index (Stype));
4355 if Is_OK_Static_Subtype (NT) then
4358 T := Base_Type (NT);
4361 return Expr_Value (Type_High_Bound (T)) -
4362 Expr_Value (Type_Low_Bound (T)) + 1;
4363 end String_Type_Len;
4365 ------------------------------------
4366 -- Subtypes_Statically_Compatible --
4367 ------------------------------------
4369 function Subtypes_Statically_Compatible
4371 T2 : Entity_Id) return Boolean
4374 if Is_Scalar_Type (T1) then
4376 -- Definitely compatible if we match
4378 if Subtypes_Statically_Match (T1, T2) then
4381 -- If either subtype is nonstatic then they're not compatible
4383 elsif not Is_Static_Subtype (T1)
4384 or else not Is_Static_Subtype (T2)
4388 -- If either type has constraint error bounds, then consider that
4389 -- they match to avoid junk cascaded errors here.
4391 elsif not Is_OK_Static_Subtype (T1)
4392 or else not Is_OK_Static_Subtype (T2)
4396 -- Base types must match, but we don't check that (should
4397 -- we???) but we do at least check that both types are
4398 -- real, or both types are not real.
4400 elsif Is_Real_Type (T1) /= Is_Real_Type (T2) then
4403 -- Here we check the bounds
4407 LB1 : constant Node_Id := Type_Low_Bound (T1);
4408 HB1 : constant Node_Id := Type_High_Bound (T1);
4409 LB2 : constant Node_Id := Type_Low_Bound (T2);
4410 HB2 : constant Node_Id := Type_High_Bound (T2);
4413 if Is_Real_Type (T1) then
4415 (Expr_Value_R (LB1) > Expr_Value_R (HB1))
4417 (Expr_Value_R (LB2) <= Expr_Value_R (LB1)
4419 Expr_Value_R (HB1) <= Expr_Value_R (HB2));
4423 (Expr_Value (LB1) > Expr_Value (HB1))
4425 (Expr_Value (LB2) <= Expr_Value (LB1)
4427 Expr_Value (HB1) <= Expr_Value (HB2));
4432 elsif Is_Access_Type (T1) then
4433 return not Is_Constrained (T2)
4434 or else Subtypes_Statically_Match
4435 (Designated_Type (T1), Designated_Type (T2));
4438 return (Is_Composite_Type (T1) and then not Is_Constrained (T2))
4439 or else Subtypes_Statically_Match (T1, T2);
4441 end Subtypes_Statically_Compatible;
4443 -------------------------------
4444 -- Subtypes_Statically_Match --
4445 -------------------------------
4447 -- Subtypes statically match if they have statically matching constraints
4448 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
4449 -- they are the same identical constraint, or if they are static and the
4450 -- values match (RM 4.9.1(1)).
4452 function Subtypes_Statically_Match (T1, T2 : Entity_Id) return Boolean is
4454 -- A type always statically matches itself
4461 elsif Is_Scalar_Type (T1) then
4463 -- Base types must be the same
4465 if Base_Type (T1) /= Base_Type (T2) then
4469 -- A constrained numeric subtype never matches an unconstrained
4470 -- subtype, i.e. both types must be constrained or unconstrained.
4472 -- To understand the requirement for this test, see RM 4.9.1(1).
4473 -- As is made clear in RM 3.5.4(11), type Integer, for example
4474 -- is a constrained subtype with constraint bounds matching the
4475 -- bounds of its corresponding unconstrained base type. In this
4476 -- situation, Integer and Integer'Base do not statically match,
4477 -- even though they have the same bounds.
4479 -- We only apply this test to types in Standard and types that
4480 -- appear in user programs. That way, we do not have to be
4481 -- too careful about setting Is_Constrained right for itypes.
4483 if Is_Numeric_Type (T1)
4484 and then (Is_Constrained (T1) /= Is_Constrained (T2))
4485 and then (Scope (T1) = Standard_Standard
4486 or else Comes_From_Source (T1))
4487 and then (Scope (T2) = Standard_Standard
4488 or else Comes_From_Source (T2))
4492 -- A generic scalar type does not statically match its base
4493 -- type (AI-311). In this case we make sure that the formals,
4494 -- which are first subtypes of their bases, are constrained.
4496 elsif Is_Generic_Type (T1)
4497 and then Is_Generic_Type (T2)
4498 and then (Is_Constrained (T1) /= Is_Constrained (T2))
4503 -- If there was an error in either range, then just assume
4504 -- the types statically match to avoid further junk errors
4506 if Error_Posted (Scalar_Range (T1))
4508 Error_Posted (Scalar_Range (T2))
4513 -- Otherwise both types have bound that can be compared
4516 LB1 : constant Node_Id := Type_Low_Bound (T1);
4517 HB1 : constant Node_Id := Type_High_Bound (T1);
4518 LB2 : constant Node_Id := Type_Low_Bound (T2);
4519 HB2 : constant Node_Id := Type_High_Bound (T2);
4522 -- If the bounds are the same tree node, then match
4524 if LB1 = LB2 and then HB1 = HB2 then
4527 -- Otherwise bounds must be static and identical value
4530 if not Is_Static_Subtype (T1)
4531 or else not Is_Static_Subtype (T2)
4535 -- If either type has constraint error bounds, then say
4536 -- that they match to avoid junk cascaded errors here.
4538 elsif not Is_OK_Static_Subtype (T1)
4539 or else not Is_OK_Static_Subtype (T2)
4543 elsif Is_Real_Type (T1) then
4545 (Expr_Value_R (LB1) = Expr_Value_R (LB2))
4547 (Expr_Value_R (HB1) = Expr_Value_R (HB2));
4551 Expr_Value (LB1) = Expr_Value (LB2)
4553 Expr_Value (HB1) = Expr_Value (HB2);
4558 -- Type with discriminants
4560 elsif Has_Discriminants (T1) or else Has_Discriminants (T2) then
4562 -- Because of view exchanges in multiple instantiations, conformance
4563 -- checking might try to match a partial view of a type with no
4564 -- discriminants with a full view that has defaulted discriminants.
4565 -- In such a case, use the discriminant constraint of the full view,
4566 -- which must exist because we know that the two subtypes have the
4569 if Has_Discriminants (T1) /= Has_Discriminants (T2) then
4571 if Is_Private_Type (T2)
4572 and then Present (Full_View (T2))
4573 and then Has_Discriminants (Full_View (T2))
4575 return Subtypes_Statically_Match (T1, Full_View (T2));
4577 elsif Is_Private_Type (T1)
4578 and then Present (Full_View (T1))
4579 and then Has_Discriminants (Full_View (T1))
4581 return Subtypes_Statically_Match (Full_View (T1), T2);
4592 DL1 : constant Elist_Id := Discriminant_Constraint (T1);
4593 DL2 : constant Elist_Id := Discriminant_Constraint (T2);
4601 elsif Is_Constrained (T1) /= Is_Constrained (T2) then
4605 -- Now loop through the discriminant constraints
4607 -- Note: the guard here seems necessary, since it is possible at
4608 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
4610 if Present (DL1) and then Present (DL2) then
4611 DA1 := First_Elmt (DL1);
4612 DA2 := First_Elmt (DL2);
4613 while Present (DA1) loop
4615 Expr1 : constant Node_Id := Node (DA1);
4616 Expr2 : constant Node_Id := Node (DA2);
4619 if not Is_Static_Expression (Expr1)
4620 or else not Is_Static_Expression (Expr2)
4624 -- If either expression raised a constraint error,
4625 -- consider the expressions as matching, since this
4626 -- helps to prevent cascading errors.
4628 elsif Raises_Constraint_Error (Expr1)
4629 or else Raises_Constraint_Error (Expr2)
4633 elsif Expr_Value (Expr1) /= Expr_Value (Expr2) then
4646 -- A definite type does not match an indefinite or classwide type
4647 -- However, a generic type with unknown discriminants may be
4648 -- instantiated with a type with no discriminants, and conformance
4649 -- checking on an inherited operation may compare the actual with
4650 -- the subtype that renames it in the instance.
4653 Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
4656 Is_Generic_Actual_Type (T1) or else Is_Generic_Actual_Type (T2);
4660 elsif Is_Array_Type (T1) then
4662 -- If either subtype is unconstrained then both must be,
4663 -- and if both are unconstrained then no further checking
4666 if not Is_Constrained (T1) or else not Is_Constrained (T2) then
4667 return not (Is_Constrained (T1) or else Is_Constrained (T2));
4670 -- Both subtypes are constrained, so check that the index
4671 -- subtypes statically match.
4674 Index1 : Node_Id := First_Index (T1);
4675 Index2 : Node_Id := First_Index (T2);
4678 while Present (Index1) loop
4680 Subtypes_Statically_Match (Etype (Index1), Etype (Index2))
4685 Next_Index (Index1);
4686 Next_Index (Index2);
4692 elsif Is_Access_Type (T1) then
4693 if Can_Never_Be_Null (T1) /= Can_Never_Be_Null (T2) then
4696 elsif Ekind (T1) = E_Access_Subprogram_Type
4697 or else Ekind (T1) = E_Anonymous_Access_Subprogram_Type
4701 (Designated_Type (T1),
4702 Designated_Type (T2));
4705 Subtypes_Statically_Match
4706 (Designated_Type (T1),
4707 Designated_Type (T2))
4708 and then Is_Access_Constant (T1) = Is_Access_Constant (T2);
4711 -- All other types definitely match
4716 end Subtypes_Statically_Match;
4722 function Test (Cond : Boolean) return Uint is
4731 ---------------------------------
4732 -- Test_Expression_Is_Foldable --
4733 ---------------------------------
4737 procedure Test_Expression_Is_Foldable
4747 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
4751 -- If operand is Any_Type, just propagate to result and do not
4752 -- try to fold, this prevents cascaded errors.
4754 if Etype (Op1) = Any_Type then
4755 Set_Etype (N, Any_Type);
4758 -- If operand raises constraint error, then replace node N with the
4759 -- raise constraint error node, and we are obviously not foldable.
4760 -- Note that this replacement inherits the Is_Static_Expression flag
4761 -- from the operand.
4763 elsif Raises_Constraint_Error (Op1) then
4764 Rewrite_In_Raise_CE (N, Op1);
4767 -- If the operand is not static, then the result is not static, and
4768 -- all we have to do is to check the operand since it is now known
4769 -- to appear in a non-static context.
4771 elsif not Is_Static_Expression (Op1) then
4772 Check_Non_Static_Context (Op1);
4773 Fold := Compile_Time_Known_Value (Op1);
4776 -- An expression of a formal modular type is not foldable because
4777 -- the modulus is unknown.
4779 elsif Is_Modular_Integer_Type (Etype (Op1))
4780 and then Is_Generic_Type (Etype (Op1))
4782 Check_Non_Static_Context (Op1);
4785 -- Here we have the case of an operand whose type is OK, which is
4786 -- static, and which does not raise constraint error, we can fold.
4789 Set_Is_Static_Expression (N);
4793 end Test_Expression_Is_Foldable;
4797 procedure Test_Expression_Is_Foldable
4804 Rstat : constant Boolean := Is_Static_Expression (Op1)
4805 and then Is_Static_Expression (Op2);
4811 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
4815 -- If either operand is Any_Type, just propagate to result and
4816 -- do not try to fold, this prevents cascaded errors.
4818 if Etype (Op1) = Any_Type or else Etype (Op2) = Any_Type then
4819 Set_Etype (N, Any_Type);
4822 -- If left operand raises constraint error, then replace node N with
4823 -- the raise constraint error node, and we are obviously not foldable.
4824 -- Is_Static_Expression is set from the two operands in the normal way,
4825 -- and we check the right operand if it is in a non-static context.
4827 elsif Raises_Constraint_Error (Op1) then
4829 Check_Non_Static_Context (Op2);
4832 Rewrite_In_Raise_CE (N, Op1);
4833 Set_Is_Static_Expression (N, Rstat);
4836 -- Similar processing for the case of the right operand. Note that
4837 -- we don't use this routine for the short-circuit case, so we do
4838 -- not have to worry about that special case here.
4840 elsif Raises_Constraint_Error (Op2) then
4842 Check_Non_Static_Context (Op1);
4845 Rewrite_In_Raise_CE (N, Op2);
4846 Set_Is_Static_Expression (N, Rstat);
4849 -- Exclude expressions of a generic modular type, as above
4851 elsif Is_Modular_Integer_Type (Etype (Op1))
4852 and then Is_Generic_Type (Etype (Op1))
4854 Check_Non_Static_Context (Op1);
4857 -- If result is not static, then check non-static contexts on operands
4858 -- since one of them may be static and the other one may not be static
4860 elsif not Rstat then
4861 Check_Non_Static_Context (Op1);
4862 Check_Non_Static_Context (Op2);
4863 Fold := Compile_Time_Known_Value (Op1)
4864 and then Compile_Time_Known_Value (Op2);
4867 -- Else result is static and foldable. Both operands are static,
4868 -- and neither raises constraint error, so we can definitely fold.
4871 Set_Is_Static_Expression (N);
4876 end Test_Expression_Is_Foldable;
4882 procedure To_Bits (U : Uint; B : out Bits) is
4884 for J in 0 .. B'Last loop
4885 B (J) := (U / (2 ** J)) mod 2 /= 0;
4889 --------------------
4890 -- Why_Not_Static --
4891 --------------------
4893 procedure Why_Not_Static (Expr : Node_Id) is
4894 N : constant Node_Id := Original_Node (Expr);
4898 procedure Why_Not_Static_List (L : List_Id);
4899 -- A version that can be called on a list of expressions. Finds
4900 -- all non-static violations in any element of the list.
4902 -------------------------
4903 -- Why_Not_Static_List --
4904 -------------------------
4906 procedure Why_Not_Static_List (L : List_Id) is
4910 if Is_Non_Empty_List (L) then
4912 while Present (N) loop
4917 end Why_Not_Static_List;
4919 -- Start of processing for Why_Not_Static
4922 -- If in ACATS mode (debug flag 2), then suppress all these
4923 -- messages, this avoids massive updates to the ACATS base line.
4925 if Debug_Flag_2 then
4929 -- Ignore call on error or empty node
4931 if No (Expr) or else Nkind (Expr) = N_Error then
4935 -- Preprocessing for sub expressions
4937 if Nkind (Expr) in N_Subexpr then
4939 -- Nothing to do if expression is static
4941 if Is_OK_Static_Expression (Expr) then
4945 -- Test for constraint error raised
4947 if Raises_Constraint_Error (Expr) then
4949 ("expression raises exception, cannot be static " &
4950 "(RM 4.9(34))!", N);
4954 -- If no type, then something is pretty wrong, so ignore
4956 Typ := Etype (Expr);
4962 -- Type must be scalar or string type
4964 if not Is_Scalar_Type (Typ)
4965 and then not Is_String_Type (Typ)
4968 ("static expression must have scalar or string type " &
4974 -- If we got through those checks, test particular node kind
4977 when N_Expanded_Name | N_Identifier | N_Operator_Symbol =>
4980 if Is_Named_Number (E) then
4983 elsif Ekind (E) = E_Constant then
4984 if not Is_Static_Expression (Constant_Value (E)) then
4986 ("& is not a static constant (RM 4.9(5))!", N, E);
4991 ("& is not static constant or named number " &
4992 "(RM 4.9(5))!", N, E);
4995 when N_Binary_Op | N_Short_Circuit | N_Membership_Test =>
4996 if Nkind (N) in N_Op_Shift then
4998 ("shift functions are never static (RM 4.9(6,18))!", N);
5001 Why_Not_Static (Left_Opnd (N));
5002 Why_Not_Static (Right_Opnd (N));
5006 Why_Not_Static (Right_Opnd (N));
5008 when N_Attribute_Reference =>
5009 Why_Not_Static_List (Expressions (N));
5011 E := Etype (Prefix (N));
5013 if E = Standard_Void_Type then
5017 -- Special case non-scalar'Size since this is a common error
5019 if Attribute_Name (N) = Name_Size then
5021 ("size attribute is only static for scalar type " &
5022 "(RM 4.9(7,8))", N);
5026 elsif Is_Array_Type (E) then
5027 if Attribute_Name (N) /= Name_First
5029 Attribute_Name (N) /= Name_Last
5031 Attribute_Name (N) /= Name_Length
5034 ("static array attribute must be Length, First, or Last " &
5037 -- Since we know the expression is not-static (we already
5038 -- tested for this, must mean array is not static).
5042 ("prefix is non-static array (RM 4.9(8))!", Prefix (N));
5047 -- Special case generic types, since again this is a common
5048 -- source of confusion.
5050 elsif Is_Generic_Actual_Type (E)
5055 ("attribute of generic type is never static " &
5056 "(RM 4.9(7,8))!", N);
5058 elsif Is_Static_Subtype (E) then
5061 elsif Is_Scalar_Type (E) then
5063 ("prefix type for attribute is not static scalar subtype " &
5068 ("static attribute must apply to array/scalar type " &
5069 "(RM 4.9(7,8))!", N);
5072 when N_String_Literal =>
5074 ("subtype of string literal is non-static (RM 4.9(4))!", N);
5076 when N_Explicit_Dereference =>
5078 ("explicit dereference is never static (RM 4.9)!", N);
5080 when N_Function_Call =>
5081 Why_Not_Static_List (Parameter_Associations (N));
5082 Error_Msg_N ("non-static function call (RM 4.9(6,18))!", N);
5084 when N_Parameter_Association =>
5085 Why_Not_Static (Explicit_Actual_Parameter (N));
5087 when N_Indexed_Component =>
5089 ("indexed component is never static (RM 4.9)!", N);
5091 when N_Procedure_Call_Statement =>
5093 ("procedure call is never static (RM 4.9)!", N);
5095 when N_Qualified_Expression =>
5096 Why_Not_Static (Expression (N));
5098 when N_Aggregate | N_Extension_Aggregate =>
5100 ("an aggregate is never static (RM 4.9)!", N);
5103 Why_Not_Static (Low_Bound (N));
5104 Why_Not_Static (High_Bound (N));
5106 when N_Range_Constraint =>
5107 Why_Not_Static (Range_Expression (N));
5109 when N_Subtype_Indication =>
5110 Why_Not_Static (Constraint (N));
5112 when N_Selected_Component =>
5114 ("selected component is never static (RM 4.9)!", N);
5118 ("slice is never static (RM 4.9)!", N);
5120 when N_Type_Conversion =>
5121 Why_Not_Static (Expression (N));
5123 if not Is_Scalar_Type (Etype (Prefix (N)))
5124 or else not Is_Static_Subtype (Etype (Prefix (N)))
5127 ("static conversion requires static scalar subtype result " &
5131 when N_Unchecked_Type_Conversion =>
5133 ("unchecked type conversion is never static (RM 4.9)!", N);