1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2006, 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 2, 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 COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree; use Atree;
28 with Checks; use Checks;
29 with Debug; use Debug;
30 with Einfo; use Einfo;
31 with Elists; use Elists;
32 with Errout; use Errout;
33 with Eval_Fat; use Eval_Fat;
34 with Exp_Util; use Exp_Util;
36 with Nmake; use Nmake;
37 with Nlists; use Nlists;
40 with Sem_Cat; use Sem_Cat;
41 with Sem_Ch6; use Sem_Ch6;
42 with Sem_Ch8; use Sem_Ch8;
43 with Sem_Res; use Sem_Res;
44 with Sem_Util; use Sem_Util;
45 with Sem_Type; use Sem_Type;
46 with Sem_Warn; use Sem_Warn;
47 with Sinfo; use Sinfo;
48 with Snames; use Snames;
49 with Stand; use Stand;
50 with Stringt; use Stringt;
51 with Tbuild; use Tbuild;
53 package body Sem_Eval is
55 -----------------------------------------
56 -- Handling of Compile Time Evaluation --
57 -----------------------------------------
59 -- The compile time evaluation of expressions is distributed over several
60 -- Eval_xxx procedures. These procedures are called immediatedly after
61 -- a subexpression is resolved and is therefore accomplished in a bottom
62 -- up fashion. The flags are synthesized using the following approach.
64 -- Is_Static_Expression is determined by following the detailed rules
65 -- in RM 4.9(4-14). This involves testing the Is_Static_Expression
66 -- flag of the operands in many cases.
68 -- Raises_Constraint_Error is set if any of the operands have the flag
69 -- set or if an attempt to compute the value of the current expression
70 -- results in detection of a runtime constraint error.
72 -- As described in the spec, the requirement is that Is_Static_Expression
73 -- be accurately set, and in addition for nodes for which this flag is set,
74 -- Raises_Constraint_Error must also be set. Furthermore a node which has
75 -- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
76 -- requirement is that the expression value must be precomputed, and the
77 -- node is either a literal, or the name of a constant entity whose value
78 -- is a static expression.
80 -- The general approach is as follows. First compute Is_Static_Expression.
81 -- If the node is not static, then the flag is left off in the node and
82 -- we are all done. Otherwise for a static node, we test if any of the
83 -- operands will raise constraint error, and if so, propagate the flag
84 -- Raises_Constraint_Error to the result node and we are done (since the
85 -- error was already posted at a lower level).
87 -- For the case of a static node whose operands do not raise constraint
88 -- error, we attempt to evaluate the node. If this evaluation succeeds,
89 -- then the node is replaced by the result of this computation. If the
90 -- evaluation raises constraint error, then we rewrite the node with
91 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
92 -- to post appropriate error messages.
98 type Bits is array (Nat range <>) of Boolean;
99 -- Used to convert unsigned (modular) values for folding logical ops
101 -- The following definitions are used to maintain a cache of nodes that
102 -- have compile time known values. The cache is maintained only for
103 -- discrete types (the most common case), and is populated by calls to
104 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
105 -- since it is possible for the status to change (in particular it is
106 -- possible for a node to get replaced by a constraint error node).
108 CV_Bits : constant := 5;
109 -- Number of low order bits of Node_Id value used to reference entries
110 -- in the cache table.
112 CV_Cache_Size : constant Nat := 2 ** CV_Bits;
113 -- Size of cache for compile time values
115 subtype CV_Range is Nat range 0 .. CV_Cache_Size;
117 type CV_Entry is record
122 type CV_Cache_Array is array (CV_Range) of CV_Entry;
124 CV_Cache : CV_Cache_Array := (others => (Node_High_Bound, Uint_0));
125 -- This is the actual cache, with entries consisting of node/value pairs,
126 -- and the impossible value Node_High_Bound used for unset entries.
128 -----------------------
129 -- Local Subprograms --
130 -----------------------
132 function From_Bits (B : Bits; T : Entity_Id) return Uint;
133 -- Converts a bit string of length B'Length to a Uint value to be used
134 -- for a target of type T, which is a modular type. This procedure
135 -- includes the necessary reduction by the modulus in the case of a
136 -- non-binary modulus (for a binary modulus, the bit string is the
137 -- right length any way so all is well).
139 function Get_String_Val (N : Node_Id) return Node_Id;
140 -- Given a tree node for a folded string or character value, returns
141 -- the corresponding string literal or character literal (one of the
142 -- two must be available, or the operand would not have been marked
143 -- as foldable in the earlier analysis of the operation).
145 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean;
146 -- Bits represents the number of bits in an integer value to be computed
147 -- (but the value has not been computed yet). If this value in Bits is
148 -- reasonable, a result of True is returned, with the implication that
149 -- the caller should go ahead and complete the calculation. If the value
150 -- in Bits is unreasonably large, then an error is posted on node N, and
151 -- False is returned (and the caller skips the proposed calculation).
153 procedure Out_Of_Range (N : Node_Id);
154 -- This procedure is called if it is determined that node N, which
155 -- appears in a non-static context, is a compile time known value
156 -- which is outside its range, i.e. the range of Etype. This is used
157 -- in contexts where this is an illegality if N is static, and should
158 -- generate a warning otherwise.
160 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id);
161 -- N and Exp are nodes representing an expression, Exp is known
162 -- to raise CE. N is rewritten in term of Exp in the optimal way.
164 function String_Type_Len (Stype : Entity_Id) return Uint;
165 -- Given a string type, determines the length of the index type, or,
166 -- if this index type is non-static, the length of the base type of
167 -- this index type. Note that if the string type is itself static,
168 -- then the index type is static, so the second case applies only
169 -- if the string type passed is non-static.
171 function Test (Cond : Boolean) return Uint;
172 pragma Inline (Test);
173 -- This function simply returns the appropriate Boolean'Pos value
174 -- corresponding to the value of Cond as a universal integer. It is
175 -- used for producing the result of the static evaluation of the
178 procedure Test_Expression_Is_Foldable
183 -- Tests to see if expression N whose single operand is Op1 is foldable,
184 -- i.e. the operand value is known at compile time. If the operation is
185 -- foldable, then Fold is True on return, and Stat indicates whether
186 -- the result is static (i.e. both operands were static). Note that it
187 -- is quite possible for Fold to be True, and Stat to be False, since
188 -- there are cases in which we know the value of an operand even though
189 -- it is not technically static (e.g. the static lower bound of a range
190 -- whose upper bound is non-static).
192 -- If Stat is set False on return, then Expression_Is_Foldable makes a
193 -- call to Check_Non_Static_Context on the operand. If Fold is False on
194 -- return, then all processing is complete, and the caller should
195 -- return, since there is nothing else to do.
197 procedure Test_Expression_Is_Foldable
203 -- Same processing, except applies to an expression N with two operands
206 procedure To_Bits (U : Uint; B : out Bits);
207 -- Converts a Uint value to a bit string of length B'Length
209 ------------------------------
210 -- Check_Non_Static_Context --
211 ------------------------------
213 procedure Check_Non_Static_Context (N : Node_Id) is
214 T : constant Entity_Id := Etype (N);
215 Checks_On : constant Boolean :=
216 not Index_Checks_Suppressed (T)
217 and not Range_Checks_Suppressed (T);
220 -- Ignore cases of non-scalar types or error types
222 if T = Any_Type or else not Is_Scalar_Type (T) then
226 -- At this stage we have a scalar type. If we have an expression
227 -- that raises CE, then we already issued a warning or error msg
228 -- so there is nothing more to be done in this routine.
230 if Raises_Constraint_Error (N) then
234 -- Now we have a scalar type which is not marked as raising a
235 -- constraint error exception. The main purpose of this routine
236 -- is to deal with static expressions appearing in a non-static
237 -- context. That means that if we do not have a static expression
238 -- then there is not much to do. The one case that we deal with
239 -- here is that if we have a floating-point value that is out of
240 -- range, then we post a warning that an infinity will result.
242 if not Is_Static_Expression (N) then
243 if Is_Floating_Point_Type (T)
244 and then Is_Out_Of_Range (N, Base_Type (T))
247 ("?float value out of range, infinity will be generated", N);
253 -- Here we have the case of outer level static expression of
254 -- scalar type, where the processing of this procedure is needed.
256 -- For real types, this is where we convert the value to a machine
257 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should
258 -- only need to do this if the parent is a constant declaration,
259 -- since in other cases, gigi should do the necessary conversion
260 -- correctly, but experimentation shows that this is not the case
261 -- on all machines, in particular if we do not convert all literals
262 -- to machine values in non-static contexts, then ACVC test C490001
263 -- fails on Sparc/Solaris and SGI/Irix.
265 if Nkind (N) = N_Real_Literal
266 and then not Is_Machine_Number (N)
267 and then not Is_Generic_Type (Etype (N))
268 and then Etype (N) /= Universal_Real
270 -- Check that value is in bounds before converting to machine
271 -- number, so as not to lose case where value overflows in the
272 -- least significant bit or less. See B490001.
274 if Is_Out_Of_Range (N, Base_Type (T)) then
279 -- Note: we have to copy the node, to avoid problems with conformance
280 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
282 Rewrite (N, New_Copy (N));
284 if not Is_Floating_Point_Type (T) then
286 (N, Corresponding_Integer_Value (N) * Small_Value (T));
288 elsif not UR_Is_Zero (Realval (N)) then
290 -- Note: even though RM 4.9(38) specifies biased rounding,
291 -- this has been modified by AI-100 in order to prevent
292 -- confusing differences in rounding between static and
293 -- non-static expressions. AI-100 specifies that the effect
294 -- of such rounding is implementation dependent, and in GNAT
295 -- we round to nearest even to match the run-time behavior.
298 (N, Machine (Base_Type (T), Realval (N), Round_Even, N));
301 Set_Is_Machine_Number (N);
304 -- Check for out of range universal integer. This is a non-static
305 -- context, so the integer value must be in range of the runtime
306 -- representation of universal integers.
308 -- We do this only within an expression, because that is the only
309 -- case in which non-static universal integer values can occur, and
310 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
311 -- called in contexts like the expression of a number declaration where
312 -- we certainly want to allow out of range values.
314 if Etype (N) = Universal_Integer
315 and then Nkind (N) = N_Integer_Literal
316 and then Nkind (Parent (N)) in N_Subexpr
318 (Intval (N) < Expr_Value (Type_Low_Bound (Universal_Integer))
320 Intval (N) > Expr_Value (Type_High_Bound (Universal_Integer)))
322 Apply_Compile_Time_Constraint_Error
323 (N, "non-static universal integer value out of range?",
324 CE_Range_Check_Failed);
326 -- Check out of range of base type
328 elsif Is_Out_Of_Range (N, Base_Type (T)) then
331 -- Give warning if outside subtype (where one or both of the
332 -- bounds of the subtype is static). This warning is omitted
333 -- if the expression appears in a range that could be null
334 -- (warnings are handled elsewhere for this case).
336 elsif T /= Base_Type (T)
337 and then Nkind (Parent (N)) /= N_Range
339 if Is_In_Range (N, T) then
342 elsif Is_Out_Of_Range (N, T) then
343 Apply_Compile_Time_Constraint_Error
344 (N, "value not in range of}?", CE_Range_Check_Failed);
347 Enable_Range_Check (N);
350 Set_Do_Range_Check (N, False);
353 end Check_Non_Static_Context;
355 ---------------------------------
356 -- Check_String_Literal_Length --
357 ---------------------------------
359 procedure Check_String_Literal_Length (N : Node_Id; Ttype : Entity_Id) is
361 if not Raises_Constraint_Error (N)
362 and then Is_Constrained (Ttype)
365 UI_From_Int (String_Length (Strval (N))) /= String_Type_Len (Ttype)
367 Apply_Compile_Time_Constraint_Error
368 (N, "string length wrong for}?",
369 CE_Length_Check_Failed,
374 end Check_String_Literal_Length;
376 --------------------------
377 -- Compile_Time_Compare --
378 --------------------------
380 function Compile_Time_Compare
382 Rec : Boolean := False) return Compare_Result
384 Ltyp : constant Entity_Id := Etype (L);
385 Rtyp : constant Entity_Id := Etype (R);
387 procedure Compare_Decompose
391 -- This procedure decomposes the node N into an expression node
392 -- and a signed offset, so that the value of N is equal to the
393 -- value of R plus the value V (which may be negative). If no
394 -- such decomposition is possible, then on return R is a copy
395 -- of N, and V is set to zero.
397 function Compare_Fixup (N : Node_Id) return Node_Id;
398 -- This function deals with replacing 'Last and 'First references
399 -- with their corresponding type bounds, which we then can compare.
400 -- The argument is the original node, the result is the identity,
401 -- unless we have a 'Last/'First reference in which case the value
402 -- returned is the appropriate type bound.
404 function Is_Same_Value (L, R : Node_Id) return Boolean;
405 -- Returns True iff L and R represent expressions that definitely
406 -- have identical (but not necessarily compile time known) values
407 -- Indeed the caller is expected to have already dealt with the
408 -- cases of compile time known values, so these are not tested here.
410 -----------------------
411 -- Compare_Decompose --
412 -----------------------
414 procedure Compare_Decompose
420 if Nkind (N) = N_Op_Add
421 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
424 V := Intval (Right_Opnd (N));
427 elsif Nkind (N) = N_Op_Subtract
428 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
431 V := UI_Negate (Intval (Right_Opnd (N)));
434 elsif Nkind (N) = N_Attribute_Reference then
436 if Attribute_Name (N) = Name_Succ then
437 R := First (Expressions (N));
441 elsif Attribute_Name (N) = Name_Pred then
442 R := First (Expressions (N));
450 end Compare_Decompose;
456 function Compare_Fixup (N : Node_Id) return Node_Id is
462 if Nkind (N) = N_Attribute_Reference
463 and then (Attribute_Name (N) = Name_First
465 Attribute_Name (N) = Name_Last)
467 Xtyp := Etype (Prefix (N));
469 -- If we have no type, then just abandon the attempt to do
470 -- a fixup, this is probably the result of some other error.
476 -- Dereference an access type
478 if Is_Access_Type (Xtyp) then
479 Xtyp := Designated_Type (Xtyp);
482 -- If we don't have an array type at this stage, something
483 -- is peculiar, e.g. another error, and we abandon the attempt
486 if not Is_Array_Type (Xtyp) then
490 -- Ignore unconstrained array, since bounds are not meaningful
492 if not Is_Constrained (Xtyp) then
496 if Ekind (Xtyp) = E_String_Literal_Subtype then
497 if Attribute_Name (N) = Name_First then
498 return String_Literal_Low_Bound (Xtyp);
500 else -- Attribute_Name (N) = Name_Last
501 return Make_Integer_Literal (Sloc (N),
502 Intval => Intval (String_Literal_Low_Bound (Xtyp))
503 + String_Literal_Length (Xtyp));
507 -- Find correct index type
509 Indx := First_Index (Xtyp);
511 if Present (Expressions (N)) then
512 Subs := UI_To_Int (Expr_Value (First (Expressions (N))));
514 for J in 2 .. Subs loop
515 Indx := Next_Index (Indx);
519 Xtyp := Etype (Indx);
521 if Attribute_Name (N) = Name_First then
522 return Type_Low_Bound (Xtyp);
524 else -- Attribute_Name (N) = Name_Last
525 return Type_High_Bound (Xtyp);
536 function Is_Same_Value (L, R : Node_Id) return Boolean is
537 Lf : constant Node_Id := Compare_Fixup (L);
538 Rf : constant Node_Id := Compare_Fixup (R);
540 function Is_Same_Subscript (L, R : List_Id) return Boolean;
541 -- L, R are the Expressions values from two attribute nodes
542 -- for First or Last attributes. Either may be set to No_List
543 -- if no expressions are present (indicating subscript 1).
544 -- The result is True if both expressions represent the same
545 -- subscript (note that one case is where one subscript is
546 -- missing and the other is explicitly set to 1).
548 -----------------------
549 -- Is_Same_Subscript --
550 -----------------------
552 function Is_Same_Subscript (L, R : List_Id) return Boolean is
558 return Expr_Value (First (R)) = Uint_1;
563 return Expr_Value (First (L)) = Uint_1;
565 return Expr_Value (First (L)) = Expr_Value (First (R));
568 end Is_Same_Subscript;
570 -- Start of processing for Is_Same_Value
573 -- Values are the same if they are the same identifier and the
574 -- identifier refers to a constant object (E_Constant). This
575 -- does not however apply to Float types, since we may have two
576 -- NaN values and they should never compare equal.
578 if Nkind (Lf) = N_Identifier and then Nkind (Rf) = N_Identifier
579 and then Entity (Lf) = Entity (Rf)
580 and then not Is_Floating_Point_Type (Etype (L))
581 and then (Ekind (Entity (Lf)) = E_Constant or else
582 Ekind (Entity (Lf)) = E_In_Parameter or else
583 Ekind (Entity (Lf)) = E_Loop_Parameter)
587 -- Or if they are compile time known and identical
589 elsif Compile_Time_Known_Value (Lf)
591 Compile_Time_Known_Value (Rf)
592 and then Expr_Value (Lf) = Expr_Value (Rf)
596 -- Or if they are both 'First or 'Last values applying to the
597 -- same entity (first and last don't change even if value does)
599 elsif Nkind (Lf) = N_Attribute_Reference
601 Nkind (Rf) = N_Attribute_Reference
602 and then Attribute_Name (Lf) = Attribute_Name (Rf)
603 and then (Attribute_Name (Lf) = Name_First
605 Attribute_Name (Lf) = Name_Last)
606 and then Is_Entity_Name (Prefix (Lf))
607 and then Is_Entity_Name (Prefix (Rf))
608 and then Entity (Prefix (Lf)) = Entity (Prefix (Rf))
609 and then Is_Same_Subscript (Expressions (Lf), Expressions (Rf))
613 -- All other cases, we can't tell
620 -- Start of processing for Compile_Time_Compare
623 -- If either operand could raise constraint error, then we cannot
624 -- know the result at compile time (since CE may be raised!)
626 if not (Cannot_Raise_Constraint_Error (L)
628 Cannot_Raise_Constraint_Error (R))
633 -- Identical operands are most certainly equal
638 -- If expressions have no types, then do not attempt to determine
639 -- if they are the same, since something funny is going on. One
640 -- case in which this happens is during generic template analysis,
641 -- when bounds are not fully analyzed.
643 elsif No (Ltyp) or else No (Rtyp) then
646 -- We only attempt compile time analysis for scalar values, and
647 -- not for packed arrays represented as modular types, where the
648 -- semantics of comparison is quite different.
650 elsif not Is_Scalar_Type (Ltyp)
651 or else Is_Packed_Array_Type (Ltyp)
655 -- Case where comparison involves two compile time known values
657 elsif Compile_Time_Known_Value (L)
658 and then Compile_Time_Known_Value (R)
660 -- For the floating-point case, we have to be a little careful, since
661 -- at compile time we are dealing with universal exact values, but at
662 -- runtime, these will be in non-exact target form. That's why the
663 -- returned results are LE and GE below instead of LT and GT.
665 if Is_Floating_Point_Type (Ltyp)
667 Is_Floating_Point_Type (Rtyp)
670 Lo : constant Ureal := Expr_Value_R (L);
671 Hi : constant Ureal := Expr_Value_R (R);
683 -- For the integer case we know exactly (note that this includes the
684 -- fixed-point case, where we know the run time integer values now)
688 Lo : constant Uint := Expr_Value (L);
689 Hi : constant Uint := Expr_Value (R);
702 -- Cases where at least one operand is not known at compile time
705 -- Remaining checks apply only for non-generic discrete types
707 if not Is_Discrete_Type (Ltyp)
708 or else not Is_Discrete_Type (Rtyp)
709 or else Is_Generic_Type (Ltyp)
710 or else Is_Generic_Type (Rtyp)
715 -- Here is where we check for comparisons against maximum bounds of
716 -- types, where we know that no value can be outside the bounds of
717 -- the subtype. Note that this routine is allowed to assume that all
718 -- expressions are within their subtype bounds. Callers wishing to
719 -- deal with possibly invalid values must in any case take special
720 -- steps (e.g. conversions to larger types) to avoid this kind of
721 -- optimization, which is always considered to be valid. We do not
722 -- attempt this optimization with generic types, since the type
723 -- bounds may not be meaningful in this case.
725 -- We are in danger of an infinite recursion here. It does not seem
726 -- useful to go more than one level deep, so the parameter Rec is
727 -- used to protect ourselves against this infinite recursion.
731 -- See if we can get a decisive check against one operand and
732 -- a bound of the other operand (four possible tests here).
734 case Compile_Time_Compare (L, Type_Low_Bound (Rtyp), True) is
735 when LT => return LT;
736 when LE => return LE;
737 when EQ => return LE;
741 case Compile_Time_Compare (L, Type_High_Bound (Rtyp), True) is
742 when GT => return GT;
743 when GE => return GE;
744 when EQ => return GE;
748 case Compile_Time_Compare (Type_Low_Bound (Ltyp), R, True) is
749 when GT => return GT;
750 when GE => return GE;
751 when EQ => return GE;
755 case Compile_Time_Compare (Type_High_Bound (Ltyp), R, True) is
756 when LT => return LT;
757 when LE => return LE;
758 when EQ => return LE;
763 -- Next attempt is to decompose the expressions to extract
764 -- a constant offset resulting from the use of any of the forms:
771 -- Then we see if the two expressions are the same value, and if so
772 -- the result is obtained by comparing the offsets.
781 Compare_Decompose (L, Lnode, Loffs);
782 Compare_Decompose (R, Rnode, Roffs);
784 if Is_Same_Value (Lnode, Rnode) then
785 if Loffs = Roffs then
788 elsif Loffs < Roffs then
797 -- Next attempt is to see if we have an entity compared with a
798 -- compile time known value, where there is a current value
799 -- conditional for the entity which can tell us the result.
803 -- Entity variable (left operand)
806 -- Value (right operand)
809 -- If False, we have reversed the operands
812 -- Comparison operator kind from Get_Current_Value_Condition call
815 -- Value from Get_Current_Value_Condition call
820 Result : Compare_Result;
821 -- Known result before inversion
824 if Is_Entity_Name (L)
825 and then Compile_Time_Known_Value (R)
828 Val := Expr_Value (R);
831 elsif Is_Entity_Name (R)
832 and then Compile_Time_Known_Value (L)
835 Val := Expr_Value (L);
838 -- That was the last chance at finding a compile time result
844 Get_Current_Value_Condition (Var, Op, Opn);
846 -- That was the last chance, so if we got nothing return
852 Opv := Expr_Value (Opn);
854 -- We got a comparison, so we might have something interesting
856 -- Convert LE to LT and GE to GT, just so we have fewer cases
861 elsif Op = N_Op_Ge then
866 -- Deal with equality case
877 -- Deal with inequality case
879 elsif Op = N_Op_Ne then
886 -- Deal with greater than case
888 elsif Op = N_Op_Gt then
891 elsif Opv = Val - 1 then
897 -- Deal with less than case
899 else pragma Assert (Op = N_Op_Lt);
902 elsif Opv = Val + 1 then
909 -- Deal with inverting result
913 when GT => return LT;
914 when GE => return LE;
915 when LT => return GT;
916 when LE => return GE;
917 when others => return Result;
924 end Compile_Time_Compare;
926 -------------------------------
927 -- Compile_Time_Known_Bounds --
928 -------------------------------
930 function Compile_Time_Known_Bounds (T : Entity_Id) return Boolean is
935 if not Is_Array_Type (T) then
939 Indx := First_Index (T);
940 while Present (Indx) loop
941 Typ := Underlying_Type (Etype (Indx));
942 if not Compile_Time_Known_Value (Type_Low_Bound (Typ)) then
944 elsif not Compile_Time_Known_Value (Type_High_Bound (Typ)) then
952 end Compile_Time_Known_Bounds;
954 ------------------------------
955 -- Compile_Time_Known_Value --
956 ------------------------------
958 function Compile_Time_Known_Value (Op : Node_Id) return Boolean is
959 K : constant Node_Kind := Nkind (Op);
960 CV_Ent : CV_Entry renames CV_Cache (Nat (Op) mod CV_Cache_Size);
963 -- Never known at compile time if bad type or raises constraint error
964 -- or empty (latter case occurs only as a result of a previous error)
968 or else Etype (Op) = Any_Type
969 or else Raises_Constraint_Error (Op)
974 -- If this is not a static expression and we are in configurable run
975 -- time mode, then we consider it not known at compile time. This
976 -- avoids anomalies where whether something is permitted with a given
977 -- configurable run-time library depends on how good the compiler is
978 -- at optimizing and knowing that things are constant when they
981 if Configurable_Run_Time_Mode and then not Is_Static_Expression (Op) then
985 -- If we have an entity name, then see if it is the name of a constant
986 -- and if so, test the corresponding constant value, or the name of
987 -- an enumeration literal, which is always a constant.
989 if Present (Etype (Op)) and then Is_Entity_Name (Op) then
991 E : constant Entity_Id := Entity (Op);
995 -- Never known at compile time if it is a packed array value.
996 -- We might want to try to evaluate these at compile time one
997 -- day, but we do not make that attempt now.
999 if Is_Packed_Array_Type (Etype (Op)) then
1003 if Ekind (E) = E_Enumeration_Literal then
1006 elsif Ekind (E) = E_Constant then
1007 V := Constant_Value (E);
1008 return Present (V) and then Compile_Time_Known_Value (V);
1012 -- We have a value, see if it is compile time known
1015 -- Integer literals are worth storing in the cache
1017 if K = N_Integer_Literal then
1019 CV_Ent.V := Intval (Op);
1022 -- Other literals and NULL are known at compile time
1025 K = N_Character_Literal
1029 K = N_String_Literal
1035 -- Any reference to Null_Parameter is known at compile time. No
1036 -- other attribute references (that have not already been folded)
1037 -- are known at compile time.
1039 elsif K = N_Attribute_Reference then
1040 return Attribute_Name (Op) = Name_Null_Parameter;
1044 -- If we fall through, not known at compile time
1048 -- If we get an exception while trying to do this test, then some error
1049 -- has occurred, and we simply say that the value is not known after all
1054 end Compile_Time_Known_Value;
1056 --------------------------------------
1057 -- Compile_Time_Known_Value_Or_Aggr --
1058 --------------------------------------
1060 function Compile_Time_Known_Value_Or_Aggr (Op : Node_Id) return Boolean is
1062 -- If we have an entity name, then see if it is the name of a constant
1063 -- and if so, test the corresponding constant value, or the name of
1064 -- an enumeration literal, which is always a constant.
1066 if Is_Entity_Name (Op) then
1068 E : constant Entity_Id := Entity (Op);
1072 if Ekind (E) = E_Enumeration_Literal then
1075 elsif Ekind (E) /= E_Constant then
1079 V := Constant_Value (E);
1081 and then Compile_Time_Known_Value_Or_Aggr (V);
1085 -- We have a value, see if it is compile time known
1088 if Compile_Time_Known_Value (Op) then
1091 elsif Nkind (Op) = N_Aggregate then
1093 if Present (Expressions (Op)) then
1098 Expr := First (Expressions (Op));
1099 while Present (Expr) loop
1100 if not Compile_Time_Known_Value_Or_Aggr (Expr) then
1109 if Present (Component_Associations (Op)) then
1114 Cass := First (Component_Associations (Op));
1115 while Present (Cass) loop
1117 Compile_Time_Known_Value_Or_Aggr (Expression (Cass))
1129 -- All other types of values are not known at compile time
1136 end Compile_Time_Known_Value_Or_Aggr;
1142 -- This is only called for actuals of functions that are not predefined
1143 -- operators (which have already been rewritten as operators at this
1144 -- stage), so the call can never be folded, and all that needs doing for
1145 -- the actual is to do the check for a non-static context.
1147 procedure Eval_Actual (N : Node_Id) is
1149 Check_Non_Static_Context (N);
1152 --------------------
1153 -- Eval_Allocator --
1154 --------------------
1156 -- Allocators are never static, so all we have to do is to do the
1157 -- check for a non-static context if an expression is present.
1159 procedure Eval_Allocator (N : Node_Id) is
1160 Expr : constant Node_Id := Expression (N);
1163 if Nkind (Expr) = N_Qualified_Expression then
1164 Check_Non_Static_Context (Expression (Expr));
1168 ------------------------
1169 -- Eval_Arithmetic_Op --
1170 ------------------------
1172 -- Arithmetic operations are static functions, so the result is static
1173 -- if both operands are static (RM 4.9(7), 4.9(20)).
1175 procedure Eval_Arithmetic_Op (N : Node_Id) is
1176 Left : constant Node_Id := Left_Opnd (N);
1177 Right : constant Node_Id := Right_Opnd (N);
1178 Ltype : constant Entity_Id := Etype (Left);
1179 Rtype : constant Entity_Id := Etype (Right);
1184 -- If not foldable we are done
1186 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1192 -- Fold for cases where both operands are of integer type
1194 if Is_Integer_Type (Ltype) and then Is_Integer_Type (Rtype) then
1196 Left_Int : constant Uint := Expr_Value (Left);
1197 Right_Int : constant Uint := Expr_Value (Right);
1204 Result := Left_Int + Right_Int;
1206 when N_Op_Subtract =>
1207 Result := Left_Int - Right_Int;
1209 when N_Op_Multiply =>
1212 (Num_Bits (Left_Int) + Num_Bits (Right_Int)))
1214 Result := Left_Int * Right_Int;
1221 -- The exception Constraint_Error is raised by integer
1222 -- division, rem and mod if the right operand is zero.
1224 if Right_Int = 0 then
1225 Apply_Compile_Time_Constraint_Error
1226 (N, "division by zero",
1232 Result := Left_Int / Right_Int;
1237 -- The exception Constraint_Error is raised by integer
1238 -- division, rem and mod if the right operand is zero.
1240 if Right_Int = 0 then
1241 Apply_Compile_Time_Constraint_Error
1242 (N, "mod with zero divisor",
1247 Result := Left_Int mod Right_Int;
1252 -- The exception Constraint_Error is raised by integer
1253 -- division, rem and mod if the right operand is zero.
1255 if Right_Int = 0 then
1256 Apply_Compile_Time_Constraint_Error
1257 (N, "rem with zero divisor",
1263 Result := Left_Int rem Right_Int;
1267 raise Program_Error;
1270 -- Adjust the result by the modulus if the type is a modular type
1272 if Is_Modular_Integer_Type (Ltype) then
1273 Result := Result mod Modulus (Ltype);
1275 -- For a signed integer type, check non-static overflow
1277 elsif (not Stat) and then Is_Signed_Integer_Type (Ltype) then
1279 BT : constant Entity_Id := Base_Type (Ltype);
1280 Lo : constant Uint := Expr_Value (Type_Low_Bound (BT));
1281 Hi : constant Uint := Expr_Value (Type_High_Bound (BT));
1283 if Result < Lo or else Result > Hi then
1284 Apply_Compile_Time_Constraint_Error
1285 (N, "value not in range of }?",
1286 CE_Overflow_Check_Failed,
1293 -- If we get here we can fold the result
1295 Fold_Uint (N, Result, Stat);
1298 -- Cases where at least one operand is a real. We handle the cases
1299 -- of both reals, or mixed/real integer cases (the latter happen
1300 -- only for divide and multiply, and the result is always real).
1302 elsif Is_Real_Type (Ltype) or else Is_Real_Type (Rtype) then
1309 if Is_Real_Type (Ltype) then
1310 Left_Real := Expr_Value_R (Left);
1312 Left_Real := UR_From_Uint (Expr_Value (Left));
1315 if Is_Real_Type (Rtype) then
1316 Right_Real := Expr_Value_R (Right);
1318 Right_Real := UR_From_Uint (Expr_Value (Right));
1321 if Nkind (N) = N_Op_Add then
1322 Result := Left_Real + Right_Real;
1324 elsif Nkind (N) = N_Op_Subtract then
1325 Result := Left_Real - Right_Real;
1327 elsif Nkind (N) = N_Op_Multiply then
1328 Result := Left_Real * Right_Real;
1330 else pragma Assert (Nkind (N) = N_Op_Divide);
1331 if UR_Is_Zero (Right_Real) then
1332 Apply_Compile_Time_Constraint_Error
1333 (N, "division by zero", CE_Divide_By_Zero);
1337 Result := Left_Real / Right_Real;
1340 Fold_Ureal (N, Result, Stat);
1343 end Eval_Arithmetic_Op;
1345 ----------------------------
1346 -- Eval_Character_Literal --
1347 ----------------------------
1349 -- Nothing to be done!
1351 procedure Eval_Character_Literal (N : Node_Id) is
1352 pragma Warnings (Off, N);
1355 end Eval_Character_Literal;
1361 -- Static function calls are either calls to predefined operators
1362 -- with static arguments, or calls to functions that rename a literal.
1363 -- Only the latter case is handled here, predefined operators are
1364 -- constant-folded elsewhere.
1366 -- If the function is itself inherited (see 7423-001) the literal of
1367 -- the parent type must be explicitly converted to the return type
1370 procedure Eval_Call (N : Node_Id) is
1371 Loc : constant Source_Ptr := Sloc (N);
1372 Typ : constant Entity_Id := Etype (N);
1376 if Nkind (N) = N_Function_Call
1377 and then No (Parameter_Associations (N))
1378 and then Is_Entity_Name (Name (N))
1379 and then Present (Alias (Entity (Name (N))))
1380 and then Is_Enumeration_Type (Base_Type (Typ))
1382 Lit := Alias (Entity (Name (N)));
1383 while Present (Alias (Lit)) loop
1387 if Ekind (Lit) = E_Enumeration_Literal then
1388 if Base_Type (Etype (Lit)) /= Base_Type (Typ) then
1390 (N, Convert_To (Typ, New_Occurrence_Of (Lit, Loc)));
1392 Rewrite (N, New_Occurrence_Of (Lit, Loc));
1400 ------------------------
1401 -- Eval_Concatenation --
1402 ------------------------
1404 -- Concatenation is a static function, so the result is static if
1405 -- both operands are static (RM 4.9(7), 4.9(21)).
1407 procedure Eval_Concatenation (N : Node_Id) is
1408 Left : constant Node_Id := Left_Opnd (N);
1409 Right : constant Node_Id := Right_Opnd (N);
1410 C_Typ : constant Entity_Id := Root_Type (Component_Type (Etype (N)));
1415 -- Concatenation is never static in Ada 83, so if Ada 83
1416 -- check operand non-static context
1418 if Ada_Version = Ada_83
1419 and then Comes_From_Source (N)
1421 Check_Non_Static_Context (Left);
1422 Check_Non_Static_Context (Right);
1426 -- If not foldable we are done. In principle concatenation that yields
1427 -- any string type is static (i.e. an array type of character types).
1428 -- However, character types can include enumeration literals, and
1429 -- concatenation in that case cannot be described by a literal, so we
1430 -- only consider the operation static if the result is an array of
1431 -- (a descendant of) a predefined character type.
1433 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1435 if (C_Typ = Standard_Character
1436 or else C_Typ = Standard_Wide_Character
1437 or else C_Typ = Standard_Wide_Wide_Character)
1442 Set_Is_Static_Expression (N, False);
1446 -- Compile time string concatenation
1448 -- ??? Note that operands that are aggregates can be marked as
1449 -- static, so we should attempt at a later stage to fold
1450 -- concatenations with such aggregates.
1453 Left_Str : constant Node_Id := Get_String_Val (Left);
1455 Right_Str : constant Node_Id := Get_String_Val (Right);
1458 -- Establish new string literal, and store left operand. We make
1459 -- sure to use the special Start_String that takes an operand if
1460 -- the left operand is a string literal. Since this is optimized
1461 -- in the case where that is the most recently created string
1462 -- literal, we ensure efficient time/space behavior for the
1463 -- case of a concatenation of a series of string literals.
1465 if Nkind (Left_Str) = N_String_Literal then
1466 Left_Len := String_Length (Strval (Left_Str));
1467 Start_String (Strval (Left_Str));
1470 Store_String_Char (UI_To_CC (Char_Literal_Value (Left_Str)));
1474 -- Now append the characters of the right operand
1476 if Nkind (Right_Str) = N_String_Literal then
1478 S : constant String_Id := Strval (Right_Str);
1481 for J in 1 .. String_Length (S) loop
1482 Store_String_Char (Get_String_Char (S, J));
1486 Store_String_Char (UI_To_CC (Char_Literal_Value (Right_Str)));
1489 Set_Is_Static_Expression (N, Stat);
1493 -- If left operand is the empty string, the result is the
1494 -- right operand, including its bounds if anomalous.
1497 and then Is_Array_Type (Etype (Right))
1498 and then Etype (Right) /= Any_String
1500 Set_Etype (N, Etype (Right));
1503 Fold_Str (N, End_String, True);
1506 end Eval_Concatenation;
1508 ---------------------------------
1509 -- Eval_Conditional_Expression --
1510 ---------------------------------
1512 -- This GNAT internal construct can never be statically folded, so the
1513 -- only required processing is to do the check for non-static context
1514 -- for the two expression operands.
1516 procedure Eval_Conditional_Expression (N : Node_Id) is
1517 Condition : constant Node_Id := First (Expressions (N));
1518 Then_Expr : constant Node_Id := Next (Condition);
1519 Else_Expr : constant Node_Id := Next (Then_Expr);
1522 Check_Non_Static_Context (Then_Expr);
1523 Check_Non_Static_Context (Else_Expr);
1524 end Eval_Conditional_Expression;
1526 ----------------------
1527 -- Eval_Entity_Name --
1528 ----------------------
1530 -- This procedure is used for identifiers and expanded names other than
1531 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
1532 -- static if they denote a static constant (RM 4.9(6)) or if the name
1533 -- denotes an enumeration literal (RM 4.9(22)).
1535 procedure Eval_Entity_Name (N : Node_Id) is
1536 Def_Id : constant Entity_Id := Entity (N);
1540 -- Enumeration literals are always considered to be constants
1541 -- and cannot raise constraint error (RM 4.9(22)).
1543 if Ekind (Def_Id) = E_Enumeration_Literal then
1544 Set_Is_Static_Expression (N);
1547 -- A name is static if it denotes a static constant (RM 4.9(5)), and
1548 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
1549 -- it does not violate 10.2.1(8) here, since this is not a variable.
1551 elsif Ekind (Def_Id) = E_Constant then
1553 -- Deferred constants must always be treated as nonstatic
1554 -- outside the scope of their full view.
1556 if Present (Full_View (Def_Id))
1557 and then not In_Open_Scopes (Scope (Def_Id))
1561 Val := Constant_Value (Def_Id);
1564 if Present (Val) then
1565 Set_Is_Static_Expression
1566 (N, Is_Static_Expression (Val)
1567 and then Is_Static_Subtype (Etype (Def_Id)));
1568 Set_Raises_Constraint_Error (N, Raises_Constraint_Error (Val));
1570 if not Is_Static_Expression (N)
1571 and then not Is_Generic_Type (Etype (N))
1573 Validate_Static_Object_Name (N);
1580 -- Fall through if the name is not static
1582 Validate_Static_Object_Name (N);
1583 end Eval_Entity_Name;
1585 ----------------------------
1586 -- Eval_Indexed_Component --
1587 ----------------------------
1589 -- Indexed components are never static, so we need to perform the check
1590 -- for non-static context on the index values. Then, we check if the
1591 -- value can be obtained at compile time, even though it is non-static.
1593 procedure Eval_Indexed_Component (N : Node_Id) is
1597 -- Check for non-static context on index values
1599 Expr := First (Expressions (N));
1600 while Present (Expr) loop
1601 Check_Non_Static_Context (Expr);
1605 -- If the indexed component appears in an object renaming declaration
1606 -- then we do not want to try to evaluate it, since in this case we
1607 -- need the identity of the array element.
1609 if Nkind (Parent (N)) = N_Object_Renaming_Declaration then
1612 -- Similarly if the indexed component appears as the prefix of an
1613 -- attribute we don't want to evaluate it, because at least for
1614 -- some cases of attributes we need the identify (e.g. Access, Size)
1616 elsif Nkind (Parent (N)) = N_Attribute_Reference then
1620 -- Note: there are other cases, such as the left side of an assignment,
1621 -- or an OUT parameter for a call, where the replacement results in the
1622 -- illegal use of a constant, But these cases are illegal in the first
1623 -- place, so the replacement, though silly, is harmless.
1625 -- Now see if this is a constant array reference
1627 if List_Length (Expressions (N)) = 1
1628 and then Is_Entity_Name (Prefix (N))
1629 and then Ekind (Entity (Prefix (N))) = E_Constant
1630 and then Present (Constant_Value (Entity (Prefix (N))))
1633 Loc : constant Source_Ptr := Sloc (N);
1634 Arr : constant Node_Id := Constant_Value (Entity (Prefix (N)));
1635 Sub : constant Node_Id := First (Expressions (N));
1641 -- Linear one's origin subscript value for array reference
1644 -- Lower bound of the first array index
1647 -- Value from constant array
1650 Atyp := Etype (Arr);
1652 if Is_Access_Type (Atyp) then
1653 Atyp := Designated_Type (Atyp);
1656 -- If we have an array type (we should have but perhaps there
1657 -- are error cases where this is not the case), then see if we
1658 -- can do a constant evaluation of the array reference.
1660 if Is_Array_Type (Atyp) then
1661 if Ekind (Atyp) = E_String_Literal_Subtype then
1662 Lbd := String_Literal_Low_Bound (Atyp);
1664 Lbd := Type_Low_Bound (Etype (First_Index (Atyp)));
1667 if Compile_Time_Known_Value (Sub)
1668 and then Nkind (Arr) = N_Aggregate
1669 and then Compile_Time_Known_Value (Lbd)
1670 and then Is_Discrete_Type (Component_Type (Atyp))
1672 Lin := UI_To_Int (Expr_Value (Sub) - Expr_Value (Lbd)) + 1;
1674 if List_Length (Expressions (Arr)) >= Lin then
1675 Elm := Pick (Expressions (Arr), Lin);
1677 -- If the resulting expression is compile time known,
1678 -- then we can rewrite the indexed component with this
1679 -- value, being sure to mark the result as non-static.
1680 -- We also reset the Sloc, in case this generates an
1681 -- error later on (e.g. 136'Access).
1683 if Compile_Time_Known_Value (Elm) then
1684 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
1685 Set_Is_Static_Expression (N, False);
1693 end Eval_Indexed_Component;
1695 --------------------------
1696 -- Eval_Integer_Literal --
1697 --------------------------
1699 -- Numeric literals are static (RM 4.9(1)), and have already been marked
1700 -- as static by the analyzer. The reason we did it that early is to allow
1701 -- the possibility of turning off the Is_Static_Expression flag after
1702 -- analysis, but before resolution, when integer literals are generated
1703 -- in the expander that do not correspond to static expressions.
1705 procedure Eval_Integer_Literal (N : Node_Id) is
1706 T : constant Entity_Id := Etype (N);
1708 function In_Any_Integer_Context return Boolean;
1709 -- If the literal is resolved with a specific type in a context
1710 -- where the expected type is Any_Integer, there are no range checks
1711 -- on the literal. By the time the literal is evaluated, it carries
1712 -- the type imposed by the enclosing expression, and we must recover
1713 -- the context to determine that Any_Integer is meant.
1715 ----------------------------
1716 -- To_Any_Integer_Context --
1717 ----------------------------
1719 function In_Any_Integer_Context return Boolean is
1720 Par : constant Node_Id := Parent (N);
1721 K : constant Node_Kind := Nkind (Par);
1724 -- Any_Integer also appears in digits specifications for real types,
1725 -- but those have bounds smaller that those of any integer base
1726 -- type, so we can safely ignore these cases.
1728 return K = N_Number_Declaration
1729 or else K = N_Attribute_Reference
1730 or else K = N_Attribute_Definition_Clause
1731 or else K = N_Modular_Type_Definition
1732 or else K = N_Signed_Integer_Type_Definition;
1733 end In_Any_Integer_Context;
1735 -- Start of processing for Eval_Integer_Literal
1739 -- If the literal appears in a non-expression context, then it is
1740 -- certainly appearing in a non-static context, so check it. This
1741 -- is actually a redundant check, since Check_Non_Static_Context
1742 -- would check it, but it seems worth while avoiding the call.
1744 if Nkind (Parent (N)) not in N_Subexpr
1745 and then not In_Any_Integer_Context
1747 Check_Non_Static_Context (N);
1750 -- Modular integer literals must be in their base range
1752 if Is_Modular_Integer_Type (T)
1753 and then Is_Out_Of_Range (N, Base_Type (T))
1757 end Eval_Integer_Literal;
1759 ---------------------
1760 -- Eval_Logical_Op --
1761 ---------------------
1763 -- Logical operations are static functions, so the result is potentially
1764 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
1766 procedure Eval_Logical_Op (N : Node_Id) is
1767 Left : constant Node_Id := Left_Opnd (N);
1768 Right : constant Node_Id := Right_Opnd (N);
1773 -- If not foldable we are done
1775 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1781 -- Compile time evaluation of logical operation
1784 Left_Int : constant Uint := Expr_Value (Left);
1785 Right_Int : constant Uint := Expr_Value (Right);
1788 if Is_Modular_Integer_Type (Etype (N)) then
1790 Left_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
1791 Right_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
1794 To_Bits (Left_Int, Left_Bits);
1795 To_Bits (Right_Int, Right_Bits);
1797 -- Note: should really be able to use array ops instead of
1798 -- these loops, but they weren't working at the time ???
1800 if Nkind (N) = N_Op_And then
1801 for J in Left_Bits'Range loop
1802 Left_Bits (J) := Left_Bits (J) and Right_Bits (J);
1805 elsif Nkind (N) = N_Op_Or then
1806 for J in Left_Bits'Range loop
1807 Left_Bits (J) := Left_Bits (J) or Right_Bits (J);
1811 pragma Assert (Nkind (N) = N_Op_Xor);
1813 for J in Left_Bits'Range loop
1814 Left_Bits (J) := Left_Bits (J) xor Right_Bits (J);
1818 Fold_Uint (N, From_Bits (Left_Bits, Etype (N)), Stat);
1822 pragma Assert (Is_Boolean_Type (Etype (N)));
1824 if Nkind (N) = N_Op_And then
1826 Test (Is_True (Left_Int) and then Is_True (Right_Int)), Stat);
1828 elsif Nkind (N) = N_Op_Or then
1830 Test (Is_True (Left_Int) or else Is_True (Right_Int)), Stat);
1833 pragma Assert (Nkind (N) = N_Op_Xor);
1835 Test (Is_True (Left_Int) xor Is_True (Right_Int)), Stat);
1839 end Eval_Logical_Op;
1841 ------------------------
1842 -- Eval_Membership_Op --
1843 ------------------------
1845 -- A membership test is potentially static if the expression is static,
1846 -- and the range is a potentially static range, or is a subtype mark
1847 -- denoting a static subtype (RM 4.9(12)).
1849 procedure Eval_Membership_Op (N : Node_Id) is
1850 Left : constant Node_Id := Left_Opnd (N);
1851 Right : constant Node_Id := Right_Opnd (N);
1860 -- Ignore if error in either operand, except to make sure that
1861 -- Any_Type is properly propagated to avoid junk cascaded errors.
1863 if Etype (Left) = Any_Type
1864 or else Etype (Right) = Any_Type
1866 Set_Etype (N, Any_Type);
1870 -- Case of right operand is a subtype name
1872 if Is_Entity_Name (Right) then
1873 Def_Id := Entity (Right);
1875 if (Is_Scalar_Type (Def_Id) or else Is_String_Type (Def_Id))
1876 and then Is_OK_Static_Subtype (Def_Id)
1878 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
1880 if not Fold or else not Stat then
1884 Check_Non_Static_Context (Left);
1888 -- For string membership tests we will check the length
1891 if not Is_String_Type (Def_Id) then
1892 Lo := Type_Low_Bound (Def_Id);
1893 Hi := Type_High_Bound (Def_Id);
1900 -- Case of right operand is a range
1903 if Is_Static_Range (Right) then
1904 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
1906 if not Fold or else not Stat then
1909 -- If one bound of range raises CE, then don't try to fold
1911 elsif not Is_OK_Static_Range (Right) then
1912 Check_Non_Static_Context (Left);
1917 Check_Non_Static_Context (Left);
1921 -- Here we know range is an OK static range
1923 Lo := Low_Bound (Right);
1924 Hi := High_Bound (Right);
1927 -- For strings we check that the length of the string expression is
1928 -- compatible with the string subtype if the subtype is constrained,
1929 -- or if unconstrained then the test is always true.
1931 if Is_String_Type (Etype (Right)) then
1932 if not Is_Constrained (Etype (Right)) then
1937 Typlen : constant Uint := String_Type_Len (Etype (Right));
1938 Strlen : constant Uint :=
1939 UI_From_Int (String_Length (Strval (Get_String_Val (Left))));
1941 Result := (Typlen = Strlen);
1945 -- Fold the membership test. We know we have a static range and Lo
1946 -- and Hi are set to the expressions for the end points of this range.
1948 elsif Is_Real_Type (Etype (Right)) then
1950 Leftval : constant Ureal := Expr_Value_R (Left);
1953 Result := Expr_Value_R (Lo) <= Leftval
1954 and then Leftval <= Expr_Value_R (Hi);
1959 Leftval : constant Uint := Expr_Value (Left);
1962 Result := Expr_Value (Lo) <= Leftval
1963 and then Leftval <= Expr_Value (Hi);
1967 if Nkind (N) = N_Not_In then
1968 Result := not Result;
1971 Fold_Uint (N, Test (Result), True);
1972 Warn_On_Known_Condition (N);
1973 end Eval_Membership_Op;
1975 ------------------------
1976 -- Eval_Named_Integer --
1977 ------------------------
1979 procedure Eval_Named_Integer (N : Node_Id) is
1982 Expr_Value (Expression (Declaration_Node (Entity (N)))), True);
1983 end Eval_Named_Integer;
1985 ---------------------
1986 -- Eval_Named_Real --
1987 ---------------------
1989 procedure Eval_Named_Real (N : Node_Id) is
1992 Expr_Value_R (Expression (Declaration_Node (Entity (N)))), True);
1993 end Eval_Named_Real;
1999 -- Exponentiation is a static functions, so the result is potentially
2000 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2002 procedure Eval_Op_Expon (N : Node_Id) is
2003 Left : constant Node_Id := Left_Opnd (N);
2004 Right : constant Node_Id := Right_Opnd (N);
2009 -- If not foldable we are done
2011 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2017 -- Fold exponentiation operation
2020 Right_Int : constant Uint := Expr_Value (Right);
2025 if Is_Integer_Type (Etype (Left)) then
2027 Left_Int : constant Uint := Expr_Value (Left);
2031 -- Exponentiation of an integer raises the exception
2032 -- Constraint_Error for a negative exponent (RM 4.5.6)
2034 if Right_Int < 0 then
2035 Apply_Compile_Time_Constraint_Error
2036 (N, "integer exponent negative",
2037 CE_Range_Check_Failed,
2042 if OK_Bits (N, Num_Bits (Left_Int) * Right_Int) then
2043 Result := Left_Int ** Right_Int;
2048 if Is_Modular_Integer_Type (Etype (N)) then
2049 Result := Result mod Modulus (Etype (N));
2052 Fold_Uint (N, Result, Stat);
2060 Left_Real : constant Ureal := Expr_Value_R (Left);
2063 -- Cannot have a zero base with a negative exponent
2065 if UR_Is_Zero (Left_Real) then
2067 if Right_Int < 0 then
2068 Apply_Compile_Time_Constraint_Error
2069 (N, "zero ** negative integer",
2070 CE_Range_Check_Failed,
2074 Fold_Ureal (N, Ureal_0, Stat);
2078 Fold_Ureal (N, Left_Real ** Right_Int, Stat);
2089 -- The not operation is a static functions, so the result is potentially
2090 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
2092 procedure Eval_Op_Not (N : Node_Id) is
2093 Right : constant Node_Id := Right_Opnd (N);
2098 -- If not foldable we are done
2100 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
2106 -- Fold not operation
2109 Rint : constant Uint := Expr_Value (Right);
2110 Typ : constant Entity_Id := Etype (N);
2113 -- Negation is equivalent to subtracting from the modulus minus
2114 -- one. For a binary modulus this is equivalent to the ones-
2115 -- component of the original value. For non-binary modulus this
2116 -- is an arbitrary but consistent definition.
2118 if Is_Modular_Integer_Type (Typ) then
2119 Fold_Uint (N, Modulus (Typ) - 1 - Rint, Stat);
2122 pragma Assert (Is_Boolean_Type (Typ));
2123 Fold_Uint (N, Test (not Is_True (Rint)), Stat);
2126 Set_Is_Static_Expression (N, Stat);
2130 -------------------------------
2131 -- Eval_Qualified_Expression --
2132 -------------------------------
2134 -- A qualified expression is potentially static if its subtype mark denotes
2135 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2137 procedure Eval_Qualified_Expression (N : Node_Id) is
2138 Operand : constant Node_Id := Expression (N);
2139 Target_Type : constant Entity_Id := Entity (Subtype_Mark (N));
2146 -- Can only fold if target is string or scalar and subtype is static
2147 -- Also, do not fold if our parent is an allocator (this is because
2148 -- the qualified expression is really part of the syntactic structure
2149 -- of an allocator, and we do not want to end up with something that
2150 -- corresponds to "new 1" where the 1 is the result of folding a
2151 -- qualified expression).
2153 if not Is_Static_Subtype (Target_Type)
2154 or else Nkind (Parent (N)) = N_Allocator
2156 Check_Non_Static_Context (Operand);
2158 -- If operand is known to raise constraint_error, set the
2159 -- flag on the expression so it does not get optimized away.
2161 if Nkind (Operand) = N_Raise_Constraint_Error then
2162 Set_Raises_Constraint_Error (N);
2168 -- If not foldable we are done
2170 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
2175 -- Don't try fold if target type has constraint error bounds
2177 elsif not Is_OK_Static_Subtype (Target_Type) then
2178 Set_Raises_Constraint_Error (N);
2182 -- Here we will fold, save Print_In_Hex indication
2184 Hex := Nkind (Operand) = N_Integer_Literal
2185 and then Print_In_Hex (Operand);
2187 -- Fold the result of qualification
2189 if Is_Discrete_Type (Target_Type) then
2190 Fold_Uint (N, Expr_Value (Operand), Stat);
2192 -- Preserve Print_In_Hex indication
2194 if Hex and then Nkind (N) = N_Integer_Literal then
2195 Set_Print_In_Hex (N);
2198 elsif Is_Real_Type (Target_Type) then
2199 Fold_Ureal (N, Expr_Value_R (Operand), Stat);
2202 Fold_Str (N, Strval (Get_String_Val (Operand)), Stat);
2205 Set_Is_Static_Expression (N, False);
2207 Check_String_Literal_Length (N, Target_Type);
2213 -- The expression may be foldable but not static
2215 Set_Is_Static_Expression (N, Stat);
2217 if Is_Out_Of_Range (N, Etype (N)) then
2220 end Eval_Qualified_Expression;
2222 -----------------------
2223 -- Eval_Real_Literal --
2224 -----------------------
2226 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2227 -- as static by the analyzer. The reason we did it that early is to allow
2228 -- the possibility of turning off the Is_Static_Expression flag after
2229 -- analysis, but before resolution, when integer literals are generated
2230 -- in the expander that do not correspond to static expressions.
2232 procedure Eval_Real_Literal (N : Node_Id) is
2234 -- If the literal appears in a non-expression context, then it is
2235 -- certainly appearing in a non-static context, so check it.
2237 if Nkind (Parent (N)) not in N_Subexpr then
2238 Check_Non_Static_Context (N);
2241 end Eval_Real_Literal;
2243 ------------------------
2244 -- Eval_Relational_Op --
2245 ------------------------
2247 -- Relational operations are static functions, so the result is static
2248 -- if both operands are static (RM 4.9(7), 4.9(20)).
2250 procedure Eval_Relational_Op (N : Node_Id) is
2251 Left : constant Node_Id := Left_Opnd (N);
2252 Right : constant Node_Id := Right_Opnd (N);
2253 Typ : constant Entity_Id := Etype (Left);
2259 -- One special case to deal with first. If we can tell that
2260 -- the result will be false because the lengths of one or
2261 -- more index subtypes are compile time known and different,
2262 -- then we can replace the entire result by False. We only
2263 -- do this for one dimensional arrays, because the case of
2264 -- multi-dimensional arrays is rare and too much trouble!
2266 if Is_Array_Type (Typ)
2267 and then Number_Dimensions (Typ) = 1
2268 and then (Nkind (N) = N_Op_Eq
2269 or else Nkind (N) = N_Op_Ne)
2271 if Raises_Constraint_Error (Left)
2272 or else Raises_Constraint_Error (Right)
2278 procedure Get_Static_Length (Op : Node_Id; Len : out Uint);
2279 -- If Op is an expression for a constrained array with a
2280 -- known at compile time length, then Len is set to this
2281 -- (non-negative length). Otherwise Len is set to minus 1.
2283 -----------------------
2284 -- Get_Static_Length --
2285 -----------------------
2287 procedure Get_Static_Length (Op : Node_Id; Len : out Uint) is
2291 if Nkind (Op) = N_String_Literal then
2292 Len := UI_From_Int (String_Length (Strval (Op)));
2294 elsif not Is_Constrained (Etype (Op)) then
2295 Len := Uint_Minus_1;
2298 T := Etype (First_Index (Etype (Op)));
2300 if Is_Discrete_Type (T)
2302 Compile_Time_Known_Value (Type_Low_Bound (T))
2304 Compile_Time_Known_Value (Type_High_Bound (T))
2306 Len := UI_Max (Uint_0,
2307 Expr_Value (Type_High_Bound (T)) -
2308 Expr_Value (Type_Low_Bound (T)) + 1);
2310 Len := Uint_Minus_1;
2313 end Get_Static_Length;
2319 Get_Static_Length (Left, Len_L);
2320 Get_Static_Length (Right, Len_R);
2322 if Len_L /= Uint_Minus_1
2323 and then Len_R /= Uint_Minus_1
2324 and then Len_L /= Len_R
2326 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2327 Warn_On_Known_Condition (N);
2332 -- Another special case: comparisons of access types, where one or both
2333 -- operands are known to be null, so the result can be determined.
2335 elsif Is_Access_Type (Typ) then
2336 if Known_Null (Left) then
2337 if Known_Null (Right) then
2338 Fold_Uint (N, Test (Nkind (N) = N_Op_Eq), False);
2339 Warn_On_Known_Condition (N);
2342 elsif Known_Non_Null (Right) then
2343 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2344 Warn_On_Known_Condition (N);
2348 elsif Known_Non_Null (Left) then
2349 if Known_Null (Right) then
2350 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2351 Warn_On_Known_Condition (N);
2357 -- Can only fold if type is scalar (don't fold string ops)
2359 if not Is_Scalar_Type (Typ) then
2360 Check_Non_Static_Context (Left);
2361 Check_Non_Static_Context (Right);
2365 -- If not foldable we are done
2367 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2373 -- Integer and Enumeration (discrete) type cases
2375 if Is_Discrete_Type (Typ) then
2377 Left_Int : constant Uint := Expr_Value (Left);
2378 Right_Int : constant Uint := Expr_Value (Right);
2382 when N_Op_Eq => Result := Left_Int = Right_Int;
2383 when N_Op_Ne => Result := Left_Int /= Right_Int;
2384 when N_Op_Lt => Result := Left_Int < Right_Int;
2385 when N_Op_Le => Result := Left_Int <= Right_Int;
2386 when N_Op_Gt => Result := Left_Int > Right_Int;
2387 when N_Op_Ge => Result := Left_Int >= Right_Int;
2390 raise Program_Error;
2393 Fold_Uint (N, Test (Result), Stat);
2399 pragma Assert (Is_Real_Type (Typ));
2402 Left_Real : constant Ureal := Expr_Value_R (Left);
2403 Right_Real : constant Ureal := Expr_Value_R (Right);
2407 when N_Op_Eq => Result := (Left_Real = Right_Real);
2408 when N_Op_Ne => Result := (Left_Real /= Right_Real);
2409 when N_Op_Lt => Result := (Left_Real < Right_Real);
2410 when N_Op_Le => Result := (Left_Real <= Right_Real);
2411 when N_Op_Gt => Result := (Left_Real > Right_Real);
2412 when N_Op_Ge => Result := (Left_Real >= Right_Real);
2415 raise Program_Error;
2418 Fold_Uint (N, Test (Result), Stat);
2422 Warn_On_Known_Condition (N);
2423 end Eval_Relational_Op;
2429 -- Shift operations are intrinsic operations that can never be static,
2430 -- so the only processing required is to perform the required check for
2431 -- a non static context for the two operands.
2433 -- Actually we could do some compile time evaluation here some time ???
2435 procedure Eval_Shift (N : Node_Id) is
2437 Check_Non_Static_Context (Left_Opnd (N));
2438 Check_Non_Static_Context (Right_Opnd (N));
2441 ------------------------
2442 -- Eval_Short_Circuit --
2443 ------------------------
2445 -- A short circuit operation is potentially static if both operands
2446 -- are potentially static (RM 4.9 (13))
2448 procedure Eval_Short_Circuit (N : Node_Id) is
2449 Kind : constant Node_Kind := Nkind (N);
2450 Left : constant Node_Id := Left_Opnd (N);
2451 Right : constant Node_Id := Right_Opnd (N);
2453 Rstat : constant Boolean :=
2454 Is_Static_Expression (Left)
2455 and then Is_Static_Expression (Right);
2458 -- Short circuit operations are never static in Ada 83
2460 if Ada_Version = Ada_83
2461 and then Comes_From_Source (N)
2463 Check_Non_Static_Context (Left);
2464 Check_Non_Static_Context (Right);
2468 -- Now look at the operands, we can't quite use the normal call to
2469 -- Test_Expression_Is_Foldable here because short circuit operations
2470 -- are a special case, they can still be foldable, even if the right
2471 -- operand raises constraint error.
2473 -- If either operand is Any_Type, just propagate to result and
2474 -- do not try to fold, this prevents cascaded errors.
2476 if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
2477 Set_Etype (N, Any_Type);
2480 -- If left operand raises constraint error, then replace node N with
2481 -- the raise constraint error node, and we are obviously not foldable.
2482 -- Is_Static_Expression is set from the two operands in the normal way,
2483 -- and we check the right operand if it is in a non-static context.
2485 elsif Raises_Constraint_Error (Left) then
2487 Check_Non_Static_Context (Right);
2490 Rewrite_In_Raise_CE (N, Left);
2491 Set_Is_Static_Expression (N, Rstat);
2494 -- If the result is not static, then we won't in any case fold
2496 elsif not Rstat then
2497 Check_Non_Static_Context (Left);
2498 Check_Non_Static_Context (Right);
2502 -- Here the result is static, note that, unlike the normal processing
2503 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
2504 -- the right operand raises constraint error, that's because it is not
2505 -- significant if the left operand is decisive.
2507 Set_Is_Static_Expression (N);
2509 -- It does not matter if the right operand raises constraint error if
2510 -- it will not be evaluated. So deal specially with the cases where
2511 -- the right operand is not evaluated. Note that we will fold these
2512 -- cases even if the right operand is non-static, which is fine, but
2513 -- of course in these cases the result is not potentially static.
2515 Left_Int := Expr_Value (Left);
2517 if (Kind = N_And_Then and then Is_False (Left_Int))
2518 or else (Kind = N_Or_Else and Is_True (Left_Int))
2520 Fold_Uint (N, Left_Int, Rstat);
2524 -- If first operand not decisive, then it does matter if the right
2525 -- operand raises constraint error, since it will be evaluated, so
2526 -- we simply replace the node with the right operand. Note that this
2527 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
2528 -- (both are set to True in Right).
2530 if Raises_Constraint_Error (Right) then
2531 Rewrite_In_Raise_CE (N, Right);
2532 Check_Non_Static_Context (Left);
2536 -- Otherwise the result depends on the right operand
2538 Fold_Uint (N, Expr_Value (Right), Rstat);
2540 end Eval_Short_Circuit;
2546 -- Slices can never be static, so the only processing required is to
2547 -- check for non-static context if an explicit range is given.
2549 procedure Eval_Slice (N : Node_Id) is
2550 Drange : constant Node_Id := Discrete_Range (N);
2552 if Nkind (Drange) = N_Range then
2553 Check_Non_Static_Context (Low_Bound (Drange));
2554 Check_Non_Static_Context (High_Bound (Drange));
2558 -------------------------
2559 -- Eval_String_Literal --
2560 -------------------------
2562 procedure Eval_String_Literal (N : Node_Id) is
2563 Typ : constant Entity_Id := Etype (N);
2564 Bas : constant Entity_Id := Base_Type (Typ);
2570 -- Nothing to do if error type (handles cases like default expressions
2571 -- or generics where we have not yet fully resolved the type)
2573 if Bas = Any_Type or else Bas = Any_String then
2577 -- String literals are static if the subtype is static (RM 4.9(2)), so
2578 -- reset the static expression flag (it was set unconditionally in
2579 -- Analyze_String_Literal) if the subtype is non-static. We tell if
2580 -- the subtype is static by looking at the lower bound.
2582 if Ekind (Typ) = E_String_Literal_Subtype then
2583 if not Is_OK_Static_Expression (String_Literal_Low_Bound (Typ)) then
2584 Set_Is_Static_Expression (N, False);
2588 -- Here if Etype of string literal is normal Etype (not yet possible,
2589 -- but may be possible in future!)
2591 elsif not Is_OK_Static_Expression
2592 (Type_Low_Bound (Etype (First_Index (Typ))))
2594 Set_Is_Static_Expression (N, False);
2598 -- If original node was a type conversion, then result if non-static
2600 if Nkind (Original_Node (N)) = N_Type_Conversion then
2601 Set_Is_Static_Expression (N, False);
2605 -- Test for illegal Ada 95 cases. A string literal is illegal in
2606 -- Ada 95 if its bounds are outside the index base type and this
2607 -- index type is static. This can happen in only two ways. Either
2608 -- the string literal is too long, or it is null, and the lower
2609 -- bound is type'First. In either case it is the upper bound that
2610 -- is out of range of the index type.
2612 if Ada_Version >= Ada_95 then
2613 if Root_Type (Bas) = Standard_String
2615 Root_Type (Bas) = Standard_Wide_String
2617 Xtp := Standard_Positive;
2619 Xtp := Etype (First_Index (Bas));
2622 if Ekind (Typ) = E_String_Literal_Subtype then
2623 Lo := String_Literal_Low_Bound (Typ);
2625 Lo := Type_Low_Bound (Etype (First_Index (Typ)));
2628 Len := String_Length (Strval (N));
2630 if UI_From_Int (Len) > String_Type_Len (Bas) then
2631 Apply_Compile_Time_Constraint_Error
2632 (N, "string literal too long for}", CE_Length_Check_Failed,
2634 Typ => First_Subtype (Bas));
2637 and then not Is_Generic_Type (Xtp)
2639 Expr_Value (Lo) = Expr_Value (Type_Low_Bound (Base_Type (Xtp)))
2641 Apply_Compile_Time_Constraint_Error
2642 (N, "null string literal not allowed for}",
2643 CE_Length_Check_Failed,
2645 Typ => First_Subtype (Bas));
2648 end Eval_String_Literal;
2650 --------------------------
2651 -- Eval_Type_Conversion --
2652 --------------------------
2654 -- A type conversion is potentially static if its subtype mark is for a
2655 -- static scalar subtype, and its operand expression is potentially static
2658 procedure Eval_Type_Conversion (N : Node_Id) is
2659 Operand : constant Node_Id := Expression (N);
2660 Source_Type : constant Entity_Id := Etype (Operand);
2661 Target_Type : constant Entity_Id := Etype (N);
2666 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean;
2667 -- Returns true if type T is an integer type, or if it is a
2668 -- fixed-point type to be treated as an integer (i.e. the flag
2669 -- Conversion_OK is set on the conversion node).
2671 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean;
2672 -- Returns true if type T is a floating-point type, or if it is a
2673 -- fixed-point type that is not to be treated as an integer (i.e. the
2674 -- flag Conversion_OK is not set on the conversion node).
2676 ------------------------------
2677 -- To_Be_Treated_As_Integer --
2678 ------------------------------
2680 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean is
2684 or else (Is_Fixed_Point_Type (T) and then Conversion_OK (N));
2685 end To_Be_Treated_As_Integer;
2687 ---------------------------
2688 -- To_Be_Treated_As_Real --
2689 ---------------------------
2691 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean is
2694 Is_Floating_Point_Type (T)
2695 or else (Is_Fixed_Point_Type (T) and then not Conversion_OK (N));
2696 end To_Be_Treated_As_Real;
2698 -- Start of processing for Eval_Type_Conversion
2701 -- Cannot fold if target type is non-static or if semantic error
2703 if not Is_Static_Subtype (Target_Type) then
2704 Check_Non_Static_Context (Operand);
2707 elsif Error_Posted (N) then
2711 -- If not foldable we are done
2713 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
2718 -- Don't try fold if target type has constraint error bounds
2720 elsif not Is_OK_Static_Subtype (Target_Type) then
2721 Set_Raises_Constraint_Error (N);
2725 -- Remaining processing depends on operand types. Note that in the
2726 -- following type test, fixed-point counts as real unless the flag
2727 -- Conversion_OK is set, in which case it counts as integer.
2729 -- Fold conversion, case of string type. The result is not static
2731 if Is_String_Type (Target_Type) then
2732 Fold_Str (N, Strval (Get_String_Val (Operand)), False);
2736 -- Fold conversion, case of integer target type
2738 elsif To_Be_Treated_As_Integer (Target_Type) then
2743 -- Integer to integer conversion
2745 if To_Be_Treated_As_Integer (Source_Type) then
2746 Result := Expr_Value (Operand);
2748 -- Real to integer conversion
2751 Result := UR_To_Uint (Expr_Value_R (Operand));
2754 -- If fixed-point type (Conversion_OK must be set), then the
2755 -- result is logically an integer, but we must replace the
2756 -- conversion with the corresponding real literal, since the
2757 -- type from a semantic point of view is still fixed-point.
2759 if Is_Fixed_Point_Type (Target_Type) then
2761 (N, UR_From_Uint (Result) * Small_Value (Target_Type), Stat);
2763 -- Otherwise result is integer literal
2766 Fold_Uint (N, Result, Stat);
2770 -- Fold conversion, case of real target type
2772 elsif To_Be_Treated_As_Real (Target_Type) then
2777 if To_Be_Treated_As_Real (Source_Type) then
2778 Result := Expr_Value_R (Operand);
2780 Result := UR_From_Uint (Expr_Value (Operand));
2783 Fold_Ureal (N, Result, Stat);
2786 -- Enumeration types
2789 Fold_Uint (N, Expr_Value (Operand), Stat);
2792 if Is_Out_Of_Range (N, Etype (N)) then
2796 end Eval_Type_Conversion;
2802 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
2803 -- are potentially static if the operand is potentially static (RM 4.9(7))
2805 procedure Eval_Unary_Op (N : Node_Id) is
2806 Right : constant Node_Id := Right_Opnd (N);
2811 -- If not foldable we are done
2813 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
2819 -- Fold for integer case
2821 if Is_Integer_Type (Etype (N)) then
2823 Rint : constant Uint := Expr_Value (Right);
2827 -- In the case of modular unary plus and abs there is no need
2828 -- to adjust the result of the operation since if the original
2829 -- operand was in bounds the result will be in the bounds of the
2830 -- modular type. However, in the case of modular unary minus the
2831 -- result may go out of the bounds of the modular type and needs
2834 if Nkind (N) = N_Op_Plus then
2837 elsif Nkind (N) = N_Op_Minus then
2838 if Is_Modular_Integer_Type (Etype (N)) then
2839 Result := (-Rint) mod Modulus (Etype (N));
2845 pragma Assert (Nkind (N) = N_Op_Abs);
2849 Fold_Uint (N, Result, Stat);
2852 -- Fold for real case
2854 elsif Is_Real_Type (Etype (N)) then
2856 Rreal : constant Ureal := Expr_Value_R (Right);
2860 if Nkind (N) = N_Op_Plus then
2863 elsif Nkind (N) = N_Op_Minus then
2864 Result := UR_Negate (Rreal);
2867 pragma Assert (Nkind (N) = N_Op_Abs);
2868 Result := abs Rreal;
2871 Fold_Ureal (N, Result, Stat);
2876 -------------------------------
2877 -- Eval_Unchecked_Conversion --
2878 -------------------------------
2880 -- Unchecked conversions can never be static, so the only required
2881 -- processing is to check for a non-static context for the operand.
2883 procedure Eval_Unchecked_Conversion (N : Node_Id) is
2885 Check_Non_Static_Context (Expression (N));
2886 end Eval_Unchecked_Conversion;
2888 --------------------
2889 -- Expr_Rep_Value --
2890 --------------------
2892 function Expr_Rep_Value (N : Node_Id) return Uint is
2893 Kind : constant Node_Kind := Nkind (N);
2897 if Is_Entity_Name (N) then
2900 -- An enumeration literal that was either in the source or
2901 -- created as a result of static evaluation.
2903 if Ekind (Ent) = E_Enumeration_Literal then
2904 return Enumeration_Rep (Ent);
2906 -- A user defined static constant
2909 pragma Assert (Ekind (Ent) = E_Constant);
2910 return Expr_Rep_Value (Constant_Value (Ent));
2913 -- An integer literal that was either in the source or created
2914 -- as a result of static evaluation.
2916 elsif Kind = N_Integer_Literal then
2919 -- A real literal for a fixed-point type. This must be the fixed-point
2920 -- case, either the literal is of a fixed-point type, or it is a bound
2921 -- of a fixed-point type, with type universal real. In either case we
2922 -- obtain the desired value from Corresponding_Integer_Value.
2924 elsif Kind = N_Real_Literal then
2925 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
2926 return Corresponding_Integer_Value (N);
2928 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
2930 elsif Kind = N_Attribute_Reference
2931 and then Attribute_Name (N) = Name_Null_Parameter
2935 -- Otherwise must be character literal
2938 pragma Assert (Kind = N_Character_Literal);
2941 -- Since Character literals of type Standard.Character don't
2942 -- have any defining character literals built for them, they
2943 -- do not have their Entity set, so just use their Char
2944 -- code. Otherwise for user-defined character literals use
2945 -- their Pos value as usual which is the same as the Rep value.
2948 return Char_Literal_Value (N);
2950 return Enumeration_Rep (Ent);
2959 function Expr_Value (N : Node_Id) return Uint is
2960 Kind : constant Node_Kind := Nkind (N);
2961 CV_Ent : CV_Entry renames CV_Cache (Nat (N) mod CV_Cache_Size);
2966 -- If already in cache, then we know it's compile time known and
2967 -- we can return the value that was previously stored in the cache
2968 -- since compile time known values cannot change :-)
2970 if CV_Ent.N = N then
2974 -- Otherwise proceed to test value
2976 if Is_Entity_Name (N) then
2979 -- An enumeration literal that was either in the source or
2980 -- created as a result of static evaluation.
2982 if Ekind (Ent) = E_Enumeration_Literal then
2983 Val := Enumeration_Pos (Ent);
2985 -- A user defined static constant
2988 pragma Assert (Ekind (Ent) = E_Constant);
2989 Val := Expr_Value (Constant_Value (Ent));
2992 -- An integer literal that was either in the source or created
2993 -- as a result of static evaluation.
2995 elsif Kind = N_Integer_Literal then
2998 -- A real literal for a fixed-point type. This must be the fixed-point
2999 -- case, either the literal is of a fixed-point type, or it is a bound
3000 -- of a fixed-point type, with type universal real. In either case we
3001 -- obtain the desired value from Corresponding_Integer_Value.
3003 elsif Kind = N_Real_Literal then
3005 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
3006 Val := Corresponding_Integer_Value (N);
3008 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3010 elsif Kind = N_Attribute_Reference
3011 and then Attribute_Name (N) = Name_Null_Parameter
3015 -- Otherwise must be character literal
3018 pragma Assert (Kind = N_Character_Literal);
3021 -- Since Character literals of type Standard.Character don't
3022 -- have any defining character literals built for them, they
3023 -- do not have their Entity set, so just use their Char
3024 -- code. Otherwise for user-defined character literals use
3025 -- their Pos value as usual.
3028 Val := Char_Literal_Value (N);
3030 Val := Enumeration_Pos (Ent);
3034 -- Come here with Val set to value to be returned, set cache
3045 function Expr_Value_E (N : Node_Id) return Entity_Id is
3046 Ent : constant Entity_Id := Entity (N);
3049 if Ekind (Ent) = E_Enumeration_Literal then
3052 pragma Assert (Ekind (Ent) = E_Constant);
3053 return Expr_Value_E (Constant_Value (Ent));
3061 function Expr_Value_R (N : Node_Id) return Ureal is
3062 Kind : constant Node_Kind := Nkind (N);
3067 if Kind = N_Real_Literal then
3070 elsif Kind = N_Identifier or else Kind = N_Expanded_Name then
3072 pragma Assert (Ekind (Ent) = E_Constant);
3073 return Expr_Value_R (Constant_Value (Ent));
3075 elsif Kind = N_Integer_Literal then
3076 return UR_From_Uint (Expr_Value (N));
3078 -- Strange case of VAX literals, which are at this stage transformed
3079 -- into Vax_Type!x_To_y(IEEE_Literal). See Expand_N_Real_Literal in
3080 -- Exp_Vfpt for further details.
3082 elsif Vax_Float (Etype (N))
3083 and then Nkind (N) = N_Unchecked_Type_Conversion
3085 Expr := Expression (N);
3087 if Nkind (Expr) = N_Function_Call
3088 and then Present (Parameter_Associations (Expr))
3090 Expr := First (Parameter_Associations (Expr));
3092 if Nkind (Expr) = N_Real_Literal then
3093 return Realval (Expr);
3097 -- Peculiar VMS case, if we have xxx'Null_Parameter, return 0.0
3099 elsif Kind = N_Attribute_Reference
3100 and then Attribute_Name (N) = Name_Null_Parameter
3105 -- If we fall through, we have a node that cannot be interepreted
3106 -- as a compile time constant. That is definitely an error.
3108 raise Program_Error;
3115 function Expr_Value_S (N : Node_Id) return Node_Id is
3117 if Nkind (N) = N_String_Literal then
3120 pragma Assert (Ekind (Entity (N)) = E_Constant);
3121 return Expr_Value_S (Constant_Value (Entity (N)));
3125 --------------------------
3126 -- Flag_Non_Static_Expr --
3127 --------------------------
3129 procedure Flag_Non_Static_Expr (Msg : String; Expr : Node_Id) is
3131 if Error_Posted (Expr) and then not All_Errors_Mode then
3134 Error_Msg_F (Msg, Expr);
3135 Why_Not_Static (Expr);
3137 end Flag_Non_Static_Expr;
3143 procedure Fold_Str (N : Node_Id; Val : String_Id; Static : Boolean) is
3144 Loc : constant Source_Ptr := Sloc (N);
3145 Typ : constant Entity_Id := Etype (N);
3148 Rewrite (N, Make_String_Literal (Loc, Strval => Val));
3150 -- We now have the literal with the right value, both the actual type
3151 -- and the expected type of this literal are taken from the expression
3152 -- that was evaluated.
3155 Set_Is_Static_Expression (N, Static);
3164 procedure Fold_Uint (N : Node_Id; Val : Uint; Static : Boolean) is
3165 Loc : constant Source_Ptr := Sloc (N);
3166 Typ : Entity_Id := Etype (N);
3170 -- If we are folding a named number, retain the entity in the
3171 -- literal, for ASIS use.
3173 if Is_Entity_Name (N)
3174 and then Ekind (Entity (N)) = E_Named_Integer
3181 if Is_Private_Type (Typ) then
3182 Typ := Full_View (Typ);
3185 -- For a result of type integer, subsitute an N_Integer_Literal node
3186 -- for the result of the compile time evaluation of the expression.
3188 if Is_Integer_Type (Typ) then
3189 Rewrite (N, Make_Integer_Literal (Loc, Val));
3190 Set_Original_Entity (N, Ent);
3192 -- Otherwise we have an enumeration type, and we substitute either
3193 -- an N_Identifier or N_Character_Literal to represent the enumeration
3194 -- literal corresponding to the given value, which must always be in
3195 -- range, because appropriate tests have already been made for this.
3197 else pragma Assert (Is_Enumeration_Type (Typ));
3198 Rewrite (N, Get_Enum_Lit_From_Pos (Etype (N), Val, Loc));
3201 -- We now have the literal with the right value, both the actual type
3202 -- and the expected type of this literal are taken from the expression
3203 -- that was evaluated.
3206 Set_Is_Static_Expression (N, Static);
3215 procedure Fold_Ureal (N : Node_Id; Val : Ureal; Static : Boolean) is
3216 Loc : constant Source_Ptr := Sloc (N);
3217 Typ : constant Entity_Id := Etype (N);
3221 -- If we are folding a named number, retain the entity in the
3222 -- literal, for ASIS use.
3224 if Is_Entity_Name (N)
3225 and then Ekind (Entity (N)) = E_Named_Real
3232 Rewrite (N, Make_Real_Literal (Loc, Realval => Val));
3233 Set_Original_Entity (N, Ent);
3235 -- Both the actual and expected type comes from the original expression
3238 Set_Is_Static_Expression (N, Static);
3247 function From_Bits (B : Bits; T : Entity_Id) return Uint is
3251 for J in 0 .. B'Last loop
3257 if Non_Binary_Modulus (T) then
3258 V := V mod Modulus (T);
3264 --------------------
3265 -- Get_String_Val --
3266 --------------------
3268 function Get_String_Val (N : Node_Id) return Node_Id is
3270 if Nkind (N) = N_String_Literal then
3273 elsif Nkind (N) = N_Character_Literal then
3277 pragma Assert (Is_Entity_Name (N));
3278 return Get_String_Val (Constant_Value (Entity (N)));
3286 procedure Initialize is
3288 CV_Cache := (others => (Node_High_Bound, Uint_0));
3291 --------------------
3292 -- In_Subrange_Of --
3293 --------------------
3295 function In_Subrange_Of
3298 Fixed_Int : Boolean := False) return Boolean
3307 if T1 = T2 or else Is_Subtype_Of (T1, T2) then
3310 -- Never in range if both types are not scalar. Don't know if this can
3311 -- actually happen, but just in case.
3313 elsif not Is_Scalar_Type (T1) or else not Is_Scalar_Type (T1) then
3317 L1 := Type_Low_Bound (T1);
3318 H1 := Type_High_Bound (T1);
3320 L2 := Type_Low_Bound (T2);
3321 H2 := Type_High_Bound (T2);
3323 -- Check bounds to see if comparison possible at compile time
3325 if Compile_Time_Compare (L1, L2) in Compare_GE
3327 Compile_Time_Compare (H1, H2) in Compare_LE
3332 -- If bounds not comparable at compile time, then the bounds of T2
3333 -- must be compile time known or we cannot answer the query.
3335 if not Compile_Time_Known_Value (L2)
3336 or else not Compile_Time_Known_Value (H2)
3341 -- If the bounds of T1 are know at compile time then use these
3342 -- ones, otherwise use the bounds of the base type (which are of
3343 -- course always static).
3345 if not Compile_Time_Known_Value (L1) then
3346 L1 := Type_Low_Bound (Base_Type (T1));
3349 if not Compile_Time_Known_Value (H1) then
3350 H1 := Type_High_Bound (Base_Type (T1));
3353 -- Fixed point types should be considered as such only if
3354 -- flag Fixed_Int is set to False.
3356 if Is_Floating_Point_Type (T1) or else Is_Floating_Point_Type (T2)
3357 or else (Is_Fixed_Point_Type (T1) and then not Fixed_Int)
3358 or else (Is_Fixed_Point_Type (T2) and then not Fixed_Int)
3361 Expr_Value_R (L2) <= Expr_Value_R (L1)
3363 Expr_Value_R (H2) >= Expr_Value_R (H1);
3367 Expr_Value (L2) <= Expr_Value (L1)
3369 Expr_Value (H2) >= Expr_Value (H1);
3374 -- If any exception occurs, it means that we have some bug in the compiler
3375 -- possibly triggered by a previous error, or by some unforseen peculiar
3376 -- occurrence. However, this is only an optimization attempt, so there is
3377 -- really no point in crashing the compiler. Instead we just decide, too
3378 -- bad, we can't figure out the answer in this case after all.
3383 -- Debug flag K disables this behavior (useful for debugging)
3385 if Debug_Flag_K then
3396 function Is_In_Range
3399 Fixed_Int : Boolean := False;
3400 Int_Real : Boolean := False) return Boolean
3406 -- Universal types have no range limits, so always in range
3408 if Typ = Universal_Integer or else Typ = Universal_Real then
3411 -- Never in range if not scalar type. Don't know if this can
3412 -- actually happen, but our spec allows it, so we must check!
3414 elsif not Is_Scalar_Type (Typ) then
3417 -- Never in range unless we have a compile time known value
3419 elsif not Compile_Time_Known_Value (N) then
3424 Lo : constant Node_Id := Type_Low_Bound (Typ);
3425 Hi : constant Node_Id := Type_High_Bound (Typ);
3426 LB_Known : constant Boolean := Compile_Time_Known_Value (Lo);
3427 UB_Known : constant Boolean := Compile_Time_Known_Value (Hi);
3430 -- Fixed point types should be considered as such only in
3431 -- flag Fixed_Int is set to False.
3433 if Is_Floating_Point_Type (Typ)
3434 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
3437 Valr := Expr_Value_R (N);
3439 if LB_Known and then Valr >= Expr_Value_R (Lo)
3440 and then UB_Known and then Valr <= Expr_Value_R (Hi)
3448 Val := Expr_Value (N);
3450 if LB_Known and then Val >= Expr_Value (Lo)
3451 and then UB_Known and then Val <= Expr_Value (Hi)
3466 function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
3467 Typ : constant Entity_Id := Etype (Lo);
3470 if not Compile_Time_Known_Value (Lo)
3471 or else not Compile_Time_Known_Value (Hi)
3476 if Is_Discrete_Type (Typ) then
3477 return Expr_Value (Lo) > Expr_Value (Hi);
3480 pragma Assert (Is_Real_Type (Typ));
3481 return Expr_Value_R (Lo) > Expr_Value_R (Hi);
3485 -----------------------------
3486 -- Is_OK_Static_Expression --
3487 -----------------------------
3489 function Is_OK_Static_Expression (N : Node_Id) return Boolean is
3491 return Is_Static_Expression (N)
3492 and then not Raises_Constraint_Error (N);
3493 end Is_OK_Static_Expression;
3495 ------------------------
3496 -- Is_OK_Static_Range --
3497 ------------------------
3499 -- A static range is a range whose bounds are static expressions, or a
3500 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
3501 -- We have already converted range attribute references, so we get the
3502 -- "or" part of this rule without needing a special test.
3504 function Is_OK_Static_Range (N : Node_Id) return Boolean is
3506 return Is_OK_Static_Expression (Low_Bound (N))
3507 and then Is_OK_Static_Expression (High_Bound (N));
3508 end Is_OK_Static_Range;
3510 --------------------------
3511 -- Is_OK_Static_Subtype --
3512 --------------------------
3514 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
3515 -- where neither bound raises constraint error when evaluated.
3517 function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean is
3518 Base_T : constant Entity_Id := Base_Type (Typ);
3519 Anc_Subt : Entity_Id;
3522 -- First a quick check on the non static subtype flag. As described
3523 -- in further detail in Einfo, this flag is not decisive in all cases,
3524 -- but if it is set, then the subtype is definitely non-static.
3526 if Is_Non_Static_Subtype (Typ) then
3530 Anc_Subt := Ancestor_Subtype (Typ);
3532 if Anc_Subt = Empty then
3536 if Is_Generic_Type (Root_Type (Base_T))
3537 or else Is_Generic_Actual_Type (Base_T)
3543 elsif Is_String_Type (Typ) then
3545 Ekind (Typ) = E_String_Literal_Subtype
3547 (Is_OK_Static_Subtype (Component_Type (Typ))
3548 and then Is_OK_Static_Subtype (Etype (First_Index (Typ))));
3552 elsif Is_Scalar_Type (Typ) then
3553 if Base_T = Typ then
3557 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so
3558 -- use Get_Type_Low,High_Bound.
3560 return Is_OK_Static_Subtype (Anc_Subt)
3561 and then Is_OK_Static_Expression (Type_Low_Bound (Typ))
3562 and then Is_OK_Static_Expression (Type_High_Bound (Typ));
3565 -- Types other than string and scalar types are never static
3570 end Is_OK_Static_Subtype;
3572 ---------------------
3573 -- Is_Out_Of_Range --
3574 ---------------------
3576 function Is_Out_Of_Range
3579 Fixed_Int : Boolean := False;
3580 Int_Real : Boolean := False) return Boolean
3586 -- Universal types have no range limits, so always in range
3588 if Typ = Universal_Integer or else Typ = Universal_Real then
3591 -- Never out of range if not scalar type. Don't know if this can
3592 -- actually happen, but our spec allows it, so we must check!
3594 elsif not Is_Scalar_Type (Typ) then
3597 -- Never out of range if this is a generic type, since the bounds
3598 -- of generic types are junk. Note that if we only checked for
3599 -- static expressions (instead of compile time known values) below,
3600 -- we would not need this check, because values of a generic type
3601 -- can never be static, but they can be known at compile time.
3603 elsif Is_Generic_Type (Typ) then
3606 -- Never out of range unless we have a compile time known value
3608 elsif not Compile_Time_Known_Value (N) then
3613 Lo : constant Node_Id := Type_Low_Bound (Typ);
3614 Hi : constant Node_Id := Type_High_Bound (Typ);
3615 LB_Known : constant Boolean := Compile_Time_Known_Value (Lo);
3616 UB_Known : constant Boolean := Compile_Time_Known_Value (Hi);
3619 -- Real types (note that fixed-point types are not treated
3620 -- as being of a real type if the flag Fixed_Int is set,
3621 -- since in that case they are regarded as integer types).
3623 if Is_Floating_Point_Type (Typ)
3624 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
3627 Valr := Expr_Value_R (N);
3629 if LB_Known and then Valr < Expr_Value_R (Lo) then
3632 elsif UB_Known and then Expr_Value_R (Hi) < Valr then
3640 Val := Expr_Value (N);
3642 if LB_Known and then Val < Expr_Value (Lo) then
3645 elsif UB_Known and then Expr_Value (Hi) < Val then
3654 end Is_Out_Of_Range;
3656 ---------------------
3657 -- Is_Static_Range --
3658 ---------------------
3660 -- A static range is a range whose bounds are static expressions, or a
3661 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
3662 -- We have already converted range attribute references, so we get the
3663 -- "or" part of this rule without needing a special test.
3665 function Is_Static_Range (N : Node_Id) return Boolean is
3667 return Is_Static_Expression (Low_Bound (N))
3668 and then Is_Static_Expression (High_Bound (N));
3669 end Is_Static_Range;
3671 -----------------------
3672 -- Is_Static_Subtype --
3673 -----------------------
3675 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
3677 function Is_Static_Subtype (Typ : Entity_Id) return Boolean is
3678 Base_T : constant Entity_Id := Base_Type (Typ);
3679 Anc_Subt : Entity_Id;
3682 -- First a quick check on the non static subtype flag. As described
3683 -- in further detail in Einfo, this flag is not decisive in all cases,
3684 -- but if it is set, then the subtype is definitely non-static.
3686 if Is_Non_Static_Subtype (Typ) then
3690 Anc_Subt := Ancestor_Subtype (Typ);
3692 if Anc_Subt = Empty then
3696 if Is_Generic_Type (Root_Type (Base_T))
3697 or else Is_Generic_Actual_Type (Base_T)
3703 elsif Is_String_Type (Typ) then
3705 Ekind (Typ) = E_String_Literal_Subtype
3707 (Is_Static_Subtype (Component_Type (Typ))
3708 and then Is_Static_Subtype (Etype (First_Index (Typ))));
3712 elsif Is_Scalar_Type (Typ) then
3713 if Base_T = Typ then
3717 return Is_Static_Subtype (Anc_Subt)
3718 and then Is_Static_Expression (Type_Low_Bound (Typ))
3719 and then Is_Static_Expression (Type_High_Bound (Typ));
3722 -- Types other than string and scalar types are never static
3727 end Is_Static_Subtype;
3729 --------------------
3730 -- Not_Null_Range --
3731 --------------------
3733 function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
3734 Typ : constant Entity_Id := Etype (Lo);
3737 if not Compile_Time_Known_Value (Lo)
3738 or else not Compile_Time_Known_Value (Hi)
3743 if Is_Discrete_Type (Typ) then
3744 return Expr_Value (Lo) <= Expr_Value (Hi);
3747 pragma Assert (Is_Real_Type (Typ));
3749 return Expr_Value_R (Lo) <= Expr_Value_R (Hi);
3757 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean is
3759 -- We allow a maximum of 500,000 bits which seems a reasonable limit
3761 if Bits < 500_000 then
3765 Error_Msg_N ("static value too large, capacity exceeded", N);
3774 procedure Out_Of_Range (N : Node_Id) is
3776 -- If we have the static expression case, then this is an illegality
3777 -- in Ada 95 mode, except that in an instance, we never generate an
3778 -- error (if the error is legitimate, it was already diagnosed in
3779 -- the template). The expression to compute the length of a packed
3780 -- array is attached to the array type itself, and deserves a separate
3783 if Is_Static_Expression (N)
3784 and then not In_Instance
3785 and then not In_Inlined_Body
3786 and then Ada_Version >= Ada_95
3788 if Nkind (Parent (N)) = N_Defining_Identifier
3789 and then Is_Array_Type (Parent (N))
3790 and then Present (Packed_Array_Type (Parent (N)))
3791 and then Present (First_Rep_Item (Parent (N)))
3794 ("length of packed array must not exceed Integer''Last",
3795 First_Rep_Item (Parent (N)));
3796 Rewrite (N, Make_Integer_Literal (Sloc (N), Uint_1));
3799 Apply_Compile_Time_Constraint_Error
3800 (N, "value not in range of}", CE_Range_Check_Failed);
3803 -- Here we generate a warning for the Ada 83 case, or when we are
3804 -- in an instance, or when we have a non-static expression case.
3807 Apply_Compile_Time_Constraint_Error
3808 (N, "value not in range of}?", CE_Range_Check_Failed);
3812 -------------------------
3813 -- Rewrite_In_Raise_CE --
3814 -------------------------
3816 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id) is
3817 Typ : constant Entity_Id := Etype (N);
3820 -- If we want to raise CE in the condition of a raise_CE node
3821 -- we may as well get rid of the condition
3823 if Present (Parent (N))
3824 and then Nkind (Parent (N)) = N_Raise_Constraint_Error
3826 Set_Condition (Parent (N), Empty);
3828 -- If the expression raising CE is a N_Raise_CE node, we can use
3829 -- that one. We just preserve the type of the context
3831 elsif Nkind (Exp) = N_Raise_Constraint_Error then
3835 -- We have to build an explicit raise_ce node
3839 Make_Raise_Constraint_Error (Sloc (Exp),
3840 Reason => CE_Range_Check_Failed));
3841 Set_Raises_Constraint_Error (N);
3844 end Rewrite_In_Raise_CE;
3846 ---------------------
3847 -- String_Type_Len --
3848 ---------------------
3850 function String_Type_Len (Stype : Entity_Id) return Uint is
3851 NT : constant Entity_Id := Etype (First_Index (Stype));
3855 if Is_OK_Static_Subtype (NT) then
3858 T := Base_Type (NT);
3861 return Expr_Value (Type_High_Bound (T)) -
3862 Expr_Value (Type_Low_Bound (T)) + 1;
3863 end String_Type_Len;
3865 ------------------------------------
3866 -- Subtypes_Statically_Compatible --
3867 ------------------------------------
3869 function Subtypes_Statically_Compatible
3871 T2 : Entity_Id) return Boolean
3874 if Is_Scalar_Type (T1) then
3876 -- Definitely compatible if we match
3878 if Subtypes_Statically_Match (T1, T2) then
3881 -- If either subtype is nonstatic then they're not compatible
3883 elsif not Is_Static_Subtype (T1)
3884 or else not Is_Static_Subtype (T2)
3888 -- If either type has constraint error bounds, then consider that
3889 -- they match to avoid junk cascaded errors here.
3891 elsif not Is_OK_Static_Subtype (T1)
3892 or else not Is_OK_Static_Subtype (T2)
3896 -- Base types must match, but we don't check that (should
3897 -- we???) but we do at least check that both types are
3898 -- real, or both types are not real.
3900 elsif Is_Real_Type (T1) /= Is_Real_Type (T2) then
3903 -- Here we check the bounds
3907 LB1 : constant Node_Id := Type_Low_Bound (T1);
3908 HB1 : constant Node_Id := Type_High_Bound (T1);
3909 LB2 : constant Node_Id := Type_Low_Bound (T2);
3910 HB2 : constant Node_Id := Type_High_Bound (T2);
3913 if Is_Real_Type (T1) then
3915 (Expr_Value_R (LB1) > Expr_Value_R (HB1))
3917 (Expr_Value_R (LB2) <= Expr_Value_R (LB1)
3919 Expr_Value_R (HB1) <= Expr_Value_R (HB2));
3923 (Expr_Value (LB1) > Expr_Value (HB1))
3925 (Expr_Value (LB2) <= Expr_Value (LB1)
3927 Expr_Value (HB1) <= Expr_Value (HB2));
3932 elsif Is_Access_Type (T1) then
3933 return not Is_Constrained (T2)
3934 or else Subtypes_Statically_Match
3935 (Designated_Type (T1), Designated_Type (T2));
3938 return (Is_Composite_Type (T1) and then not Is_Constrained (T2))
3939 or else Subtypes_Statically_Match (T1, T2);
3941 end Subtypes_Statically_Compatible;
3943 -------------------------------
3944 -- Subtypes_Statically_Match --
3945 -------------------------------
3947 -- Subtypes statically match if they have statically matching constraints
3948 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
3949 -- they are the same identical constraint, or if they are static and the
3950 -- values match (RM 4.9.1(1)).
3952 function Subtypes_Statically_Match (T1, T2 : Entity_Id) return Boolean is
3954 -- A type always statically matches itself
3961 elsif Is_Scalar_Type (T1) then
3963 -- Base types must be the same
3965 if Base_Type (T1) /= Base_Type (T2) then
3969 -- A constrained numeric subtype never matches an unconstrained
3970 -- subtype, i.e. both types must be constrained or unconstrained.
3972 -- To understand the requirement for this test, see RM 4.9.1(1).
3973 -- As is made clear in RM 3.5.4(11), type Integer, for example
3974 -- is a constrained subtype with constraint bounds matching the
3975 -- bounds of its corresponding uncontrained base type. In this
3976 -- situation, Integer and Integer'Base do not statically match,
3977 -- even though they have the same bounds.
3979 -- We only apply this test to types in Standard and types that
3980 -- appear in user programs. That way, we do not have to be
3981 -- too careful about setting Is_Constrained right for itypes.
3983 if Is_Numeric_Type (T1)
3984 and then (Is_Constrained (T1) /= Is_Constrained (T2))
3985 and then (Scope (T1) = Standard_Standard
3986 or else Comes_From_Source (T1))
3987 and then (Scope (T2) = Standard_Standard
3988 or else Comes_From_Source (T2))
3992 -- A generic scalar type does not statically match its base
3993 -- type (AI-311). In this case we make sure that the formals,
3994 -- which are first subtypes of their bases, are constrained.
3996 elsif Is_Generic_Type (T1)
3997 and then Is_Generic_Type (T2)
3998 and then (Is_Constrained (T1) /= Is_Constrained (T2))
4003 -- If there was an error in either range, then just assume
4004 -- the types statically match to avoid further junk errors
4006 if Error_Posted (Scalar_Range (T1))
4008 Error_Posted (Scalar_Range (T2))
4013 -- Otherwise both types have bound that can be compared
4016 LB1 : constant Node_Id := Type_Low_Bound (T1);
4017 HB1 : constant Node_Id := Type_High_Bound (T1);
4018 LB2 : constant Node_Id := Type_Low_Bound (T2);
4019 HB2 : constant Node_Id := Type_High_Bound (T2);
4022 -- If the bounds are the same tree node, then match
4024 if LB1 = LB2 and then HB1 = HB2 then
4027 -- Otherwise bounds must be static and identical value
4030 if not Is_Static_Subtype (T1)
4031 or else not Is_Static_Subtype (T2)
4035 -- If either type has constraint error bounds, then say
4036 -- that they match to avoid junk cascaded errors here.
4038 elsif not Is_OK_Static_Subtype (T1)
4039 or else not Is_OK_Static_Subtype (T2)
4043 elsif Is_Real_Type (T1) then
4045 (Expr_Value_R (LB1) = Expr_Value_R (LB2))
4047 (Expr_Value_R (HB1) = Expr_Value_R (HB2));
4051 Expr_Value (LB1) = Expr_Value (LB2)
4053 Expr_Value (HB1) = Expr_Value (HB2);
4058 -- Type with discriminants
4060 elsif Has_Discriminants (T1) or else Has_Discriminants (T2) then
4062 -- Because of view exchanges in multiple instantiations, conformance
4063 -- checking might try to match a partial view of a type with no
4064 -- discriminants with a full view that has defaulted discriminants.
4065 -- In such a case, use the discriminant constraint of the full view,
4066 -- which must exist because we know that the two subtypes have the
4069 if Has_Discriminants (T1) /= Has_Discriminants (T2) then
4071 if Is_Private_Type (T2)
4072 and then Present (Full_View (T2))
4073 and then Has_Discriminants (Full_View (T2))
4075 return Subtypes_Statically_Match (T1, Full_View (T2));
4077 elsif Is_Private_Type (T1)
4078 and then Present (Full_View (T1))
4079 and then Has_Discriminants (Full_View (T1))
4081 return Subtypes_Statically_Match (Full_View (T1), T2);
4092 DL1 : constant Elist_Id := Discriminant_Constraint (T1);
4093 DL2 : constant Elist_Id := Discriminant_Constraint (T2);
4095 DA1 : Elmt_Id := First_Elmt (DL1);
4096 DA2 : Elmt_Id := First_Elmt (DL2);
4102 elsif Is_Constrained (T1) /= Is_Constrained (T2) then
4106 while Present (DA1) loop
4108 Expr1 : constant Node_Id := Node (DA1);
4109 Expr2 : constant Node_Id := Node (DA2);
4112 if not Is_Static_Expression (Expr1)
4113 or else not Is_Static_Expression (Expr2)
4117 -- If either expression raised a constraint error,
4118 -- consider the expressions as matching, since this
4119 -- helps to prevent cascading errors.
4121 elsif Raises_Constraint_Error (Expr1)
4122 or else Raises_Constraint_Error (Expr2)
4126 elsif Expr_Value (Expr1) /= Expr_Value (Expr2) then
4138 -- A definite type does not match an indefinite or classwide type
4139 -- However, a generic type with unknown discriminants may be
4140 -- instantiated with a type with no discriminants, and conformance
4141 -- checking on an inherited operation may compare the actual with
4142 -- the subtype that renames it in the instance.
4145 Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
4148 Is_Generic_Actual_Type (T1) or else Is_Generic_Actual_Type (T2);
4152 elsif Is_Array_Type (T1) then
4154 -- If either subtype is unconstrained then both must be,
4155 -- and if both are unconstrained then no further checking
4158 if not Is_Constrained (T1) or else not Is_Constrained (T2) then
4159 return not (Is_Constrained (T1) or else Is_Constrained (T2));
4162 -- Both subtypes are constrained, so check that the index
4163 -- subtypes statically match.
4166 Index1 : Node_Id := First_Index (T1);
4167 Index2 : Node_Id := First_Index (T2);
4170 while Present (Index1) loop
4172 Subtypes_Statically_Match (Etype (Index1), Etype (Index2))
4177 Next_Index (Index1);
4178 Next_Index (Index2);
4184 elsif Is_Access_Type (T1) then
4185 if Can_Never_Be_Null (T1) /= Can_Never_Be_Null (T2) then
4188 elsif Ekind (T1) = E_Access_Subprogram_Type
4189 or else Ekind (T1) = E_Anonymous_Access_Subprogram_Type
4193 (Designated_Type (T1),
4194 Designated_Type (T2));
4197 Subtypes_Statically_Match
4198 (Designated_Type (T1),
4199 Designated_Type (T2))
4200 and then Is_Access_Constant (T1) = Is_Access_Constant (T2);
4203 -- All other types definitely match
4208 end Subtypes_Statically_Match;
4214 function Test (Cond : Boolean) return Uint is
4223 ---------------------------------
4224 -- Test_Expression_Is_Foldable --
4225 ---------------------------------
4229 procedure Test_Expression_Is_Foldable
4239 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
4243 -- If operand is Any_Type, just propagate to result and do not
4244 -- try to fold, this prevents cascaded errors.
4246 if Etype (Op1) = Any_Type then
4247 Set_Etype (N, Any_Type);
4250 -- If operand raises constraint error, then replace node N with the
4251 -- raise constraint error node, and we are obviously not foldable.
4252 -- Note that this replacement inherits the Is_Static_Expression flag
4253 -- from the operand.
4255 elsif Raises_Constraint_Error (Op1) then
4256 Rewrite_In_Raise_CE (N, Op1);
4259 -- If the operand is not static, then the result is not static, and
4260 -- all we have to do is to check the operand since it is now known
4261 -- to appear in a non-static context.
4263 elsif not Is_Static_Expression (Op1) then
4264 Check_Non_Static_Context (Op1);
4265 Fold := Compile_Time_Known_Value (Op1);
4268 -- An expression of a formal modular type is not foldable because
4269 -- the modulus is unknown.
4271 elsif Is_Modular_Integer_Type (Etype (Op1))
4272 and then Is_Generic_Type (Etype (Op1))
4274 Check_Non_Static_Context (Op1);
4277 -- Here we have the case of an operand whose type is OK, which is
4278 -- static, and which does not raise constraint error, we can fold.
4281 Set_Is_Static_Expression (N);
4285 end Test_Expression_Is_Foldable;
4289 procedure Test_Expression_Is_Foldable
4296 Rstat : constant Boolean := Is_Static_Expression (Op1)
4297 and then Is_Static_Expression (Op2);
4303 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
4307 -- If either operand is Any_Type, just propagate to result and
4308 -- do not try to fold, this prevents cascaded errors.
4310 if Etype (Op1) = Any_Type or else Etype (Op2) = Any_Type then
4311 Set_Etype (N, Any_Type);
4314 -- If left operand raises constraint error, then replace node N with
4315 -- the raise constraint error node, and we are obviously not foldable.
4316 -- Is_Static_Expression is set from the two operands in the normal way,
4317 -- and we check the right operand if it is in a non-static context.
4319 elsif Raises_Constraint_Error (Op1) then
4321 Check_Non_Static_Context (Op2);
4324 Rewrite_In_Raise_CE (N, Op1);
4325 Set_Is_Static_Expression (N, Rstat);
4328 -- Similar processing for the case of the right operand. Note that
4329 -- we don't use this routine for the short-circuit case, so we do
4330 -- not have to worry about that special case here.
4332 elsif Raises_Constraint_Error (Op2) then
4334 Check_Non_Static_Context (Op1);
4337 Rewrite_In_Raise_CE (N, Op2);
4338 Set_Is_Static_Expression (N, Rstat);
4341 -- Exclude expressions of a generic modular type, as above
4343 elsif Is_Modular_Integer_Type (Etype (Op1))
4344 and then Is_Generic_Type (Etype (Op1))
4346 Check_Non_Static_Context (Op1);
4349 -- If result is not static, then check non-static contexts on operands
4350 -- since one of them may be static and the other one may not be static
4352 elsif not Rstat then
4353 Check_Non_Static_Context (Op1);
4354 Check_Non_Static_Context (Op2);
4355 Fold := Compile_Time_Known_Value (Op1)
4356 and then Compile_Time_Known_Value (Op2);
4359 -- Else result is static and foldable. Both operands are static,
4360 -- and neither raises constraint error, so we can definitely fold.
4363 Set_Is_Static_Expression (N);
4368 end Test_Expression_Is_Foldable;
4374 procedure To_Bits (U : Uint; B : out Bits) is
4376 for J in 0 .. B'Last loop
4377 B (J) := (U / (2 ** J)) mod 2 /= 0;
4381 --------------------
4382 -- Why_Not_Static --
4383 --------------------
4385 procedure Why_Not_Static (Expr : Node_Id) is
4386 N : constant Node_Id := Original_Node (Expr);
4390 procedure Why_Not_Static_List (L : List_Id);
4391 -- A version that can be called on a list of expressions. Finds
4392 -- all non-static violations in any element of the list.
4394 -------------------------
4395 -- Why_Not_Static_List --
4396 -------------------------
4398 procedure Why_Not_Static_List (L : List_Id) is
4402 if Is_Non_Empty_List (L) then
4404 while Present (N) loop
4409 end Why_Not_Static_List;
4411 -- Start of processing for Why_Not_Static
4414 -- If in ACATS mode (debug flag 2), then suppress all these
4415 -- messages, this avoids massive updates to the ACATS base line.
4417 if Debug_Flag_2 then
4421 -- Ignore call on error or empty node
4423 if No (Expr) or else Nkind (Expr) = N_Error then
4427 -- Preprocessing for sub expressions
4429 if Nkind (Expr) in N_Subexpr then
4431 -- Nothing to do if expression is static
4433 if Is_OK_Static_Expression (Expr) then
4437 -- Test for constraint error raised
4439 if Raises_Constraint_Error (Expr) then
4441 ("expression raises exception, cannot be static " &
4442 "('R'M 4.9(34))!", N);
4446 -- If no type, then something is pretty wrong, so ignore
4448 Typ := Etype (Expr);
4454 -- Type must be scalar or string type
4456 if not Is_Scalar_Type (Typ)
4457 and then not Is_String_Type (Typ)
4460 ("static expression must have scalar or string type " &
4461 "('R'M 4.9(2))!", N);
4466 -- If we got through those checks, test particular node kind
4469 when N_Expanded_Name | N_Identifier | N_Operator_Symbol =>
4472 if Is_Named_Number (E) then
4475 elsif Ekind (E) = E_Constant then
4476 if not Is_Static_Expression (Constant_Value (E)) then
4478 ("& is not a static constant ('R'M 4.9(5))!", N, E);
4483 ("& is not static constant or named number " &
4484 "('R'M 4.9(5))!", N, E);
4487 when N_Binary_Op | N_And_Then | N_Or_Else | N_Membership_Test =>
4488 if Nkind (N) in N_Op_Shift then
4490 ("shift functions are never static ('R'M 4.9(6,18))!", N);
4493 Why_Not_Static (Left_Opnd (N));
4494 Why_Not_Static (Right_Opnd (N));
4498 Why_Not_Static (Right_Opnd (N));
4500 when N_Attribute_Reference =>
4501 Why_Not_Static_List (Expressions (N));
4503 E := Etype (Prefix (N));
4505 if E = Standard_Void_Type then
4509 -- Special case non-scalar'Size since this is a common error
4511 if Attribute_Name (N) = Name_Size then
4513 ("size attribute is only static for scalar type " &
4514 "('R'M 4.9(7,8))", N);
4518 elsif Is_Array_Type (E) then
4519 if Attribute_Name (N) /= Name_First
4521 Attribute_Name (N) /= Name_Last
4523 Attribute_Name (N) /= Name_Length
4526 ("static array attribute must be Length, First, or Last " &
4527 "('R'M 4.9(8))!", N);
4529 -- Since we know the expression is not-static (we already
4530 -- tested for this, must mean array is not static).
4534 ("prefix is non-static array ('R'M 4.9(8))!", Prefix (N));
4539 -- Special case generic types, since again this is a common
4540 -- source of confusion.
4542 elsif Is_Generic_Actual_Type (E)
4547 ("attribute of generic type is never static " &
4548 "('R'M 4.9(7,8))!", N);
4550 elsif Is_Static_Subtype (E) then
4553 elsif Is_Scalar_Type (E) then
4555 ("prefix type for attribute is not static scalar subtype " &
4556 "('R'M 4.9(7))!", N);
4560 ("static attribute must apply to array/scalar type " &
4561 "('R'M 4.9(7,8))!", N);
4564 when N_String_Literal =>
4566 ("subtype of string literal is non-static ('R'M 4.9(4))!", N);
4568 when N_Explicit_Dereference =>
4570 ("explicit dereference is never static ('R'M 4.9)!", N);
4572 when N_Function_Call =>
4573 Why_Not_Static_List (Parameter_Associations (N));
4574 Error_Msg_N ("non-static function call ('R'M 4.9(6,18))!", N);
4576 when N_Parameter_Association =>
4577 Why_Not_Static (Explicit_Actual_Parameter (N));
4579 when N_Indexed_Component =>
4581 ("indexed component is never static ('R'M 4.9)!", N);
4583 when N_Procedure_Call_Statement =>
4585 ("procedure call is never static ('R'M 4.9)!", N);
4587 when N_Qualified_Expression =>
4588 Why_Not_Static (Expression (N));
4590 when N_Aggregate | N_Extension_Aggregate =>
4592 ("an aggregate is never static ('R'M 4.9)!", N);
4595 Why_Not_Static (Low_Bound (N));
4596 Why_Not_Static (High_Bound (N));
4598 when N_Range_Constraint =>
4599 Why_Not_Static (Range_Expression (N));
4601 when N_Subtype_Indication =>
4602 Why_Not_Static (Constraint (N));
4604 when N_Selected_Component =>
4606 ("selected component is never static ('R'M 4.9)!", N);
4610 ("slice is never static ('R'M 4.9)!", N);
4612 when N_Type_Conversion =>
4613 Why_Not_Static (Expression (N));
4615 if not Is_Scalar_Type (Etype (Prefix (N)))
4616 or else not Is_Static_Subtype (Etype (Prefix (N)))
4619 ("static conversion requires static scalar subtype result " &
4620 "('R'M 4.9(9))!", N);
4623 when N_Unchecked_Type_Conversion =>
4625 ("unchecked type conversion is never static ('R'M 4.9)!", N);