1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2005 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, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, 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;
35 with Nmake; use Nmake;
36 with Nlists; use Nlists;
39 with Sem_Cat; use Sem_Cat;
40 with Sem_Ch8; use Sem_Ch8;
41 with Sem_Res; use Sem_Res;
42 with Sem_Util; use Sem_Util;
43 with Sem_Type; use Sem_Type;
44 with Sem_Warn; use Sem_Warn;
45 with Sinfo; use Sinfo;
46 with Snames; use Snames;
47 with Stand; use Stand;
48 with Stringt; use Stringt;
49 with Tbuild; use Tbuild;
51 package body Sem_Eval is
53 -----------------------------------------
54 -- Handling of Compile Time Evaluation --
55 -----------------------------------------
57 -- The compile time evaluation of expressions is distributed over several
58 -- Eval_xxx procedures. These procedures are called immediatedly after
59 -- a subexpression is resolved and is therefore accomplished in a bottom
60 -- up fashion. The flags are synthesized using the following approach.
62 -- Is_Static_Expression is determined by following the detailed rules
63 -- in RM 4.9(4-14). This involves testing the Is_Static_Expression
64 -- flag of the operands in many cases.
66 -- Raises_Constraint_Error is set if any of the operands have the flag
67 -- set or if an attempt to compute the value of the current expression
68 -- results in detection of a runtime constraint error.
70 -- As described in the spec, the requirement is that Is_Static_Expression
71 -- be accurately set, and in addition for nodes for which this flag is set,
72 -- Raises_Constraint_Error must also be set. Furthermore a node which has
73 -- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
74 -- requirement is that the expression value must be precomputed, and the
75 -- node is either a literal, or the name of a constant entity whose value
76 -- is a static expression.
78 -- The general approach is as follows. First compute Is_Static_Expression.
79 -- If the node is not static, then the flag is left off in the node and
80 -- we are all done. Otherwise for a static node, we test if any of the
81 -- operands will raise constraint error, and if so, propagate the flag
82 -- Raises_Constraint_Error to the result node and we are done (since the
83 -- error was already posted at a lower level).
85 -- For the case of a static node whose operands do not raise constraint
86 -- error, we attempt to evaluate the node. If this evaluation succeeds,
87 -- then the node is replaced by the result of this computation. If the
88 -- evaluation raises constraint error, then we rewrite the node with
89 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
90 -- to post appropriate error messages.
96 type Bits is array (Nat range <>) of Boolean;
97 -- Used to convert unsigned (modular) values for folding logical ops
99 -- The following definitions are used to maintain a cache of nodes that
100 -- have compile time known values. The cache is maintained only for
101 -- discrete types (the most common case), and is populated by calls to
102 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
103 -- since it is possible for the status to change (in particular it is
104 -- possible for a node to get replaced by a constraint error node).
106 CV_Bits : constant := 5;
107 -- Number of low order bits of Node_Id value used to reference entries
108 -- in the cache table.
110 CV_Cache_Size : constant Nat := 2 ** CV_Bits;
111 -- Size of cache for compile time values
113 subtype CV_Range is Nat range 0 .. CV_Cache_Size;
115 type CV_Entry is record
120 type CV_Cache_Array is array (CV_Range) of CV_Entry;
122 CV_Cache : CV_Cache_Array := (others => (Node_High_Bound, Uint_0));
123 -- This is the actual cache, with entries consisting of node/value pairs,
124 -- and the impossible value Node_High_Bound used for unset entries.
126 -----------------------
127 -- Local Subprograms --
128 -----------------------
130 function From_Bits (B : Bits; T : Entity_Id) return Uint;
131 -- Converts a bit string of length B'Length to a Uint value to be used
132 -- for a target of type T, which is a modular type. This procedure
133 -- includes the necessary reduction by the modulus in the case of a
134 -- non-binary modulus (for a binary modulus, the bit string is the
135 -- right length any way so all is well).
137 function Get_String_Val (N : Node_Id) return Node_Id;
138 -- Given a tree node for a folded string or character value, returns
139 -- the corresponding string literal or character literal (one of the
140 -- two must be available, or the operand would not have been marked
141 -- as foldable in the earlier analysis of the operation).
143 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean;
144 -- Bits represents the number of bits in an integer value to be computed
145 -- (but the value has not been computed yet). If this value in Bits is
146 -- reasonable, a result of True is returned, with the implication that
147 -- the caller should go ahead and complete the calculation. If the value
148 -- in Bits is unreasonably large, then an error is posted on node N, and
149 -- False is returned (and the caller skips the proposed calculation).
151 procedure Out_Of_Range (N : Node_Id);
152 -- This procedure is called if it is determined that node N, which
153 -- appears in a non-static context, is a compile time known value
154 -- which is outside its range, i.e. the range of Etype. This is used
155 -- in contexts where this is an illegality if N is static, and should
156 -- generate a warning otherwise.
158 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id);
159 -- N and Exp are nodes representing an expression, Exp is known
160 -- to raise CE. N is rewritten in term of Exp in the optimal way.
162 function String_Type_Len (Stype : Entity_Id) return Uint;
163 -- Given a string type, determines the length of the index type, or,
164 -- if this index type is non-static, the length of the base type of
165 -- this index type. Note that if the string type is itself static,
166 -- then the index type is static, so the second case applies only
167 -- if the string type passed is non-static.
169 function Test (Cond : Boolean) return Uint;
170 pragma Inline (Test);
171 -- This function simply returns the appropriate Boolean'Pos value
172 -- corresponding to the value of Cond as a universal integer. It is
173 -- used for producing the result of the static evaluation of the
176 procedure Test_Expression_Is_Foldable
181 -- Tests to see if expression N whose single operand is Op1 is foldable,
182 -- i.e. the operand value is known at compile time. If the operation is
183 -- foldable, then Fold is True on return, and Stat indicates whether
184 -- the result is static (i.e. both operands were static). Note that it
185 -- is quite possible for Fold to be True, and Stat to be False, since
186 -- there are cases in which we know the value of an operand even though
187 -- it is not technically static (e.g. the static lower bound of a range
188 -- whose upper bound is non-static).
190 -- If Stat is set False on return, then Expression_Is_Foldable makes a
191 -- call to Check_Non_Static_Context on the operand. If Fold is False on
192 -- return, then all processing is complete, and the caller should
193 -- return, since there is nothing else to do.
195 procedure Test_Expression_Is_Foldable
201 -- Same processing, except applies to an expression N with two operands
204 procedure To_Bits (U : Uint; B : out Bits);
205 -- Converts a Uint value to a bit string of length B'Length
207 ------------------------------
208 -- Check_Non_Static_Context --
209 ------------------------------
211 procedure Check_Non_Static_Context (N : Node_Id) is
212 T : constant Entity_Id := Etype (N);
213 Checks_On : constant Boolean :=
214 not Index_Checks_Suppressed (T)
215 and not Range_Checks_Suppressed (T);
218 -- Ignore cases of non-scalar types or error types
220 if T = Any_Type or else not Is_Scalar_Type (T) then
224 -- At this stage we have a scalar type. If we have an expression
225 -- that raises CE, then we already issued a warning or error msg
226 -- so there is nothing more to be done in this routine.
228 if Raises_Constraint_Error (N) then
232 -- Now we have a scalar type which is not marked as raising a
233 -- constraint error exception. The main purpose of this routine
234 -- is to deal with static expressions appearing in a non-static
235 -- context. That means that if we do not have a static expression
236 -- then there is not much to do. The one case that we deal with
237 -- here is that if we have a floating-point value that is out of
238 -- range, then we post a warning that an infinity will result.
240 if not Is_Static_Expression (N) then
241 if Is_Floating_Point_Type (T)
242 and then Is_Out_Of_Range (N, Base_Type (T))
245 ("?float value out of range, infinity will be generated", N);
251 -- Here we have the case of outer level static expression of
252 -- scalar type, where the processing of this procedure is needed.
254 -- For real types, this is where we convert the value to a machine
255 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should
256 -- only need to do this if the parent is a constant declaration,
257 -- since in other cases, gigi should do the necessary conversion
258 -- correctly, but experimentation shows that this is not the case
259 -- on all machines, in particular if we do not convert all literals
260 -- to machine values in non-static contexts, then ACVC test C490001
261 -- fails on Sparc/Solaris and SGI/Irix.
263 if Nkind (N) = N_Real_Literal
264 and then not Is_Machine_Number (N)
265 and then not Is_Generic_Type (Etype (N))
266 and then Etype (N) /= Universal_Real
268 -- Check that value is in bounds before converting to machine
269 -- number, so as not to lose case where value overflows in the
270 -- least significant bit or less. See B490001.
272 if Is_Out_Of_Range (N, Base_Type (T)) then
277 -- Note: we have to copy the node, to avoid problems with conformance
278 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
280 Rewrite (N, New_Copy (N));
282 if not Is_Floating_Point_Type (T) then
284 (N, Corresponding_Integer_Value (N) * Small_Value (T));
286 elsif not UR_Is_Zero (Realval (N)) then
288 -- Note: even though RM 4.9(38) specifies biased rounding,
289 -- this has been modified by AI-100 in order to prevent
290 -- confusing differences in rounding between static and
291 -- non-static expressions. AI-100 specifies that the effect
292 -- of such rounding is implementation dependent, and in GNAT
293 -- we round to nearest even to match the run-time behavior.
296 (N, Machine (Base_Type (T), Realval (N), Round_Even, N));
299 Set_Is_Machine_Number (N);
302 -- Check for out of range universal integer. This is a non-static
303 -- context, so the integer value must be in range of the runtime
304 -- representation of universal integers.
306 -- We do this only within an expression, because that is the only
307 -- case in which non-static universal integer values can occur, and
308 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
309 -- called in contexts like the expression of a number declaration where
310 -- we certainly want to allow out of range values.
312 if Etype (N) = Universal_Integer
313 and then Nkind (N) = N_Integer_Literal
314 and then Nkind (Parent (N)) in N_Subexpr
316 (Intval (N) < Expr_Value (Type_Low_Bound (Universal_Integer))
318 Intval (N) > Expr_Value (Type_High_Bound (Universal_Integer)))
320 Apply_Compile_Time_Constraint_Error
321 (N, "non-static universal integer value out of range?",
322 CE_Range_Check_Failed);
324 -- Check out of range of base type
326 elsif Is_Out_Of_Range (N, Base_Type (T)) then
329 -- Give warning if outside subtype (where one or both of the
330 -- bounds of the subtype is static). This warning is omitted
331 -- if the expression appears in a range that could be null
332 -- (warnings are handled elsewhere for this case).
334 elsif T /= Base_Type (T)
335 and then Nkind (Parent (N)) /= N_Range
337 if Is_In_Range (N, T) then
340 elsif Is_Out_Of_Range (N, T) then
341 Apply_Compile_Time_Constraint_Error
342 (N, "value not in range of}?", CE_Range_Check_Failed);
345 Enable_Range_Check (N);
348 Set_Do_Range_Check (N, False);
351 end Check_Non_Static_Context;
353 ---------------------------------
354 -- Check_String_Literal_Length --
355 ---------------------------------
357 procedure Check_String_Literal_Length (N : Node_Id; Ttype : Entity_Id) is
359 if not Raises_Constraint_Error (N)
360 and then Is_Constrained (Ttype)
363 UI_From_Int (String_Length (Strval (N))) /= String_Type_Len (Ttype)
365 Apply_Compile_Time_Constraint_Error
366 (N, "string length wrong for}?",
367 CE_Length_Check_Failed,
372 end Check_String_Literal_Length;
374 --------------------------
375 -- Compile_Time_Compare --
376 --------------------------
378 function Compile_Time_Compare
380 Rec : Boolean := False) return Compare_Result
382 Ltyp : constant Entity_Id := Etype (L);
383 Rtyp : constant Entity_Id := Etype (R);
385 procedure Compare_Decompose
389 -- This procedure decomposes the node N into an expression node
390 -- and a signed offset, so that the value of N is equal to the
391 -- value of R plus the value V (which may be negative). If no
392 -- such decomposition is possible, then on return R is a copy
393 -- of N, and V is set to zero.
395 function Compare_Fixup (N : Node_Id) return Node_Id;
396 -- This function deals with replacing 'Last and 'First references
397 -- with their corresponding type bounds, which we then can compare.
398 -- The argument is the original node, the result is the identity,
399 -- unless we have a 'Last/'First reference in which case the value
400 -- returned is the appropriate type bound.
402 function Is_Same_Value (L, R : Node_Id) return Boolean;
403 -- Returns True iff L and R represent expressions that definitely
404 -- have identical (but not necessarily compile time known) values
405 -- Indeed the caller is expected to have already dealt with the
406 -- cases of compile time known values, so these are not tested here.
408 -----------------------
409 -- Compare_Decompose --
410 -----------------------
412 procedure Compare_Decompose
418 if Nkind (N) = N_Op_Add
419 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
422 V := Intval (Right_Opnd (N));
425 elsif Nkind (N) = N_Op_Subtract
426 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
429 V := UI_Negate (Intval (Right_Opnd (N)));
432 elsif Nkind (N) = N_Attribute_Reference then
434 if Attribute_Name (N) = Name_Succ then
435 R := First (Expressions (N));
439 elsif Attribute_Name (N) = Name_Pred then
440 R := First (Expressions (N));
448 end Compare_Decompose;
454 function Compare_Fixup (N : Node_Id) return Node_Id is
460 if Nkind (N) = N_Attribute_Reference
461 and then (Attribute_Name (N) = Name_First
463 Attribute_Name (N) = Name_Last)
465 Xtyp := Etype (Prefix (N));
467 -- If we have no type, then just abandon the attempt to do
468 -- a fixup, this is probably the result of some other error.
474 -- Dereference an access type
476 if Is_Access_Type (Xtyp) then
477 Xtyp := Designated_Type (Xtyp);
480 -- If we don't have an array type at this stage, something
481 -- is peculiar, e.g. another error, and we abandon the attempt
484 if not Is_Array_Type (Xtyp) then
488 -- Ignore unconstrained array, since bounds are not meaningful
490 if not Is_Constrained (Xtyp) then
494 if Ekind (Xtyp) = E_String_Literal_Subtype then
495 if Attribute_Name (N) = Name_First then
496 return String_Literal_Low_Bound (Xtyp);
498 else -- Attribute_Name (N) = Name_Last
499 return Make_Integer_Literal (Sloc (N),
500 Intval => Intval (String_Literal_Low_Bound (Xtyp))
501 + String_Literal_Length (Xtyp));
505 -- Find correct index type
507 Indx := First_Index (Xtyp);
509 if Present (Expressions (N)) then
510 Subs := UI_To_Int (Expr_Value (First (Expressions (N))));
512 for J in 2 .. Subs loop
513 Indx := Next_Index (Indx);
517 Xtyp := Etype (Indx);
519 if Attribute_Name (N) = Name_First then
520 return Type_Low_Bound (Xtyp);
522 else -- Attribute_Name (N) = Name_Last
523 return Type_High_Bound (Xtyp);
534 function Is_Same_Value (L, R : Node_Id) return Boolean is
535 Lf : constant Node_Id := Compare_Fixup (L);
536 Rf : constant Node_Id := Compare_Fixup (R);
538 function Is_Same_Subscript (L, R : List_Id) return Boolean;
539 -- L, R are the Expressions values from two attribute nodes
540 -- for First or Last attributes. Either may be set to No_List
541 -- if no expressions are present (indicating subscript 1).
542 -- The result is True if both expressions represent the same
543 -- subscript (note that one case is where one subscript is
544 -- missing and the other is explicitly set to 1).
546 -----------------------
547 -- Is_Same_Subscript --
548 -----------------------
550 function Is_Same_Subscript (L, R : List_Id) return Boolean is
556 return Expr_Value (First (R)) = Uint_1;
561 return Expr_Value (First (L)) = Uint_1;
563 return Expr_Value (First (L)) = Expr_Value (First (R));
566 end Is_Same_Subscript;
568 -- Start of processing for Is_Same_Value
571 -- Values are the same if they are the same identifier and the
572 -- identifier refers to a constant object (E_Constant). This
573 -- does not however apply to Float types, since we may have two
574 -- NaN values and they should never compare equal.
576 if Nkind (Lf) = N_Identifier and then Nkind (Rf) = N_Identifier
577 and then Entity (Lf) = Entity (Rf)
578 and then not Is_Floating_Point_Type (Etype (L))
579 and then (Ekind (Entity (Lf)) = E_Constant or else
580 Ekind (Entity (Lf)) = E_In_Parameter or else
581 Ekind (Entity (Lf)) = E_Loop_Parameter)
585 -- Or if they are compile time known and identical
587 elsif Compile_Time_Known_Value (Lf)
589 Compile_Time_Known_Value (Rf)
590 and then Expr_Value (Lf) = Expr_Value (Rf)
594 -- Or if they are both 'First or 'Last values applying to the
595 -- same entity (first and last don't change even if value does)
597 elsif Nkind (Lf) = N_Attribute_Reference
599 Nkind (Rf) = N_Attribute_Reference
600 and then Attribute_Name (Lf) = Attribute_Name (Rf)
601 and then (Attribute_Name (Lf) = Name_First
603 Attribute_Name (Lf) = Name_Last)
604 and then Is_Entity_Name (Prefix (Lf))
605 and then Is_Entity_Name (Prefix (Rf))
606 and then Entity (Prefix (Lf)) = Entity (Prefix (Rf))
607 and then Is_Same_Subscript (Expressions (Lf), Expressions (Rf))
611 -- All other cases, we can't tell
618 -- Start of processing for Compile_Time_Compare
621 -- If either operand could raise constraint error, then we cannot
622 -- know the result at compile time (since CE may be raised!)
624 if not (Cannot_Raise_Constraint_Error (L)
626 Cannot_Raise_Constraint_Error (R))
631 -- Identical operands are most certainly equal
636 -- If expressions have no types, then do not attempt to determine
637 -- if they are the same, since something funny is going on. One
638 -- case in which this happens is during generic template analysis,
639 -- when bounds are not fully analyzed.
641 elsif No (Ltyp) or else No (Rtyp) then
644 -- We only attempt compile time analysis for scalar values, and
645 -- not for packed arrays represented as modular types, where the
646 -- semantics of comparison is quite different.
648 elsif not Is_Scalar_Type (Ltyp)
649 or else Is_Packed_Array_Type (Ltyp)
653 -- Case where comparison involves two compile time known values
655 elsif Compile_Time_Known_Value (L)
656 and then Compile_Time_Known_Value (R)
658 -- For the floating-point case, we have to be a little careful, since
659 -- at compile time we are dealing with universal exact values, but at
660 -- runtime, these will be in non-exact target form. That's why the
661 -- returned results are LE and GE below instead of LT and GT.
663 if Is_Floating_Point_Type (Ltyp)
665 Is_Floating_Point_Type (Rtyp)
668 Lo : constant Ureal := Expr_Value_R (L);
669 Hi : constant Ureal := Expr_Value_R (R);
681 -- For the integer case we know exactly (note that this includes the
682 -- fixed-point case, where we know the run time integer values now)
686 Lo : constant Uint := Expr_Value (L);
687 Hi : constant Uint := Expr_Value (R);
700 -- Cases where at least one operand is not known at compile time
703 -- Here is where we check for comparisons against maximum bounds of
704 -- types, where we know that no value can be outside the bounds of
705 -- the subtype. Note that this routine is allowed to assume that all
706 -- expressions are within their subtype bounds. Callers wishing to
707 -- deal with possibly invalid values must in any case take special
708 -- steps (e.g. conversions to larger types) to avoid this kind of
709 -- optimization, which is always considered to be valid. We do not
710 -- attempt this optimization with generic types, since the type
711 -- bounds may not be meaningful in this case.
713 -- We are in danger of an infinite recursion here. It does not seem
714 -- useful to go more than one level deep, so the parameter Rec is
715 -- used to protect ourselves against this infinite recursion.
718 and then Is_Discrete_Type (Ltyp)
719 and then Is_Discrete_Type (Rtyp)
720 and then not Is_Generic_Type (Ltyp)
721 and then not Is_Generic_Type (Rtyp)
723 -- See if we can get a decisive check against one operand and
724 -- a bound of the other operand (four possible tests here).
726 case Compile_Time_Compare (L, Type_Low_Bound (Rtyp), True) is
727 when LT => return LT;
728 when LE => return LE;
729 when EQ => return LE;
733 case Compile_Time_Compare (L, Type_High_Bound (Rtyp), True) is
734 when GT => return GT;
735 when GE => return GE;
736 when EQ => return GE;
740 case Compile_Time_Compare (Type_Low_Bound (Ltyp), R, True) is
741 when GT => return GT;
742 when GE => return GE;
743 when EQ => return GE;
747 case Compile_Time_Compare (Type_High_Bound (Ltyp), R, True) is
748 when LT => return LT;
749 when LE => return LE;
750 when EQ => return LE;
755 -- Next attempt is to decompose the expressions to extract
756 -- a constant offset resulting from the use of any of the forms:
763 -- Then we see if the two expressions are the same value, and if so
764 -- the result is obtained by comparing the offsets.
773 Compare_Decompose (L, Lnode, Loffs);
774 Compare_Decompose (R, Rnode, Roffs);
776 if Is_Same_Value (Lnode, Rnode) then
777 if Loffs = Roffs then
780 elsif Loffs < Roffs then
787 -- If the expressions are different, we cannot say at compile
788 -- time how they compare, so we return the Unknown indication.
795 end Compile_Time_Compare;
797 -------------------------------
798 -- Compile_Time_Known_Bounds --
799 -------------------------------
801 function Compile_Time_Known_Bounds (T : Entity_Id) return Boolean is
806 if not Is_Array_Type (T) then
810 Indx := First_Index (T);
811 while Present (Indx) loop
812 Typ := Underlying_Type (Etype (Indx));
813 if not Compile_Time_Known_Value (Type_Low_Bound (Typ)) then
815 elsif not Compile_Time_Known_Value (Type_High_Bound (Typ)) then
823 end Compile_Time_Known_Bounds;
825 ------------------------------
826 -- Compile_Time_Known_Value --
827 ------------------------------
829 function Compile_Time_Known_Value (Op : Node_Id) return Boolean is
830 K : constant Node_Kind := Nkind (Op);
831 CV_Ent : CV_Entry renames CV_Cache (Nat (Op) mod CV_Cache_Size);
834 -- Never known at compile time if bad type or raises constraint error
835 -- or empty (latter case occurs only as a result of a previous error)
839 or else Etype (Op) = Any_Type
840 or else Raises_Constraint_Error (Op)
845 -- If this is not a static expression and we are in configurable run
846 -- time mode, then we consider it not known at compile time. This
847 -- avoids anomalies where whether something is permitted with a given
848 -- configurable run-time library depends on how good the compiler is
849 -- at optimizing and knowing that things are constant when they
852 if Configurable_Run_Time_Mode and then not Is_Static_Expression (Op) then
856 -- If we have an entity name, then see if it is the name of a constant
857 -- and if so, test the corresponding constant value, or the name of
858 -- an enumeration literal, which is always a constant.
860 if Present (Etype (Op)) and then Is_Entity_Name (Op) then
862 E : constant Entity_Id := Entity (Op);
866 -- Never known at compile time if it is a packed array value.
867 -- We might want to try to evaluate these at compile time one
868 -- day, but we do not make that attempt now.
870 if Is_Packed_Array_Type (Etype (Op)) then
874 if Ekind (E) = E_Enumeration_Literal then
877 elsif Ekind (E) = E_Constant then
878 V := Constant_Value (E);
879 return Present (V) and then Compile_Time_Known_Value (V);
883 -- We have a value, see if it is compile time known
886 -- Integer literals are worth storing in the cache
888 if K = N_Integer_Literal then
890 CV_Ent.V := Intval (Op);
893 -- Other literals and NULL are known at compile time
896 K = N_Character_Literal
906 -- Any reference to Null_Parameter is known at compile time. No
907 -- other attribute references (that have not already been folded)
908 -- are known at compile time.
910 elsif K = N_Attribute_Reference then
911 return Attribute_Name (Op) = Name_Null_Parameter;
915 -- If we fall through, not known at compile time
919 -- If we get an exception while trying to do this test, then some error
920 -- has occurred, and we simply say that the value is not known after all
925 end Compile_Time_Known_Value;
927 --------------------------------------
928 -- Compile_Time_Known_Value_Or_Aggr --
929 --------------------------------------
931 function Compile_Time_Known_Value_Or_Aggr (Op : Node_Id) return Boolean is
933 -- If we have an entity name, then see if it is the name of a constant
934 -- and if so, test the corresponding constant value, or the name of
935 -- an enumeration literal, which is always a constant.
937 if Is_Entity_Name (Op) then
939 E : constant Entity_Id := Entity (Op);
943 if Ekind (E) = E_Enumeration_Literal then
946 elsif Ekind (E) /= E_Constant then
950 V := Constant_Value (E);
952 and then Compile_Time_Known_Value_Or_Aggr (V);
956 -- We have a value, see if it is compile time known
959 if Compile_Time_Known_Value (Op) then
962 elsif Nkind (Op) = N_Aggregate then
964 if Present (Expressions (Op)) then
969 Expr := First (Expressions (Op));
970 while Present (Expr) loop
971 if not Compile_Time_Known_Value_Or_Aggr (Expr) then
980 if Present (Component_Associations (Op)) then
985 Cass := First (Component_Associations (Op));
986 while Present (Cass) loop
988 Compile_Time_Known_Value_Or_Aggr (Expression (Cass))
1000 -- All other types of values are not known at compile time
1007 end Compile_Time_Known_Value_Or_Aggr;
1013 -- This is only called for actuals of functions that are not predefined
1014 -- operators (which have already been rewritten as operators at this
1015 -- stage), so the call can never be folded, and all that needs doing for
1016 -- the actual is to do the check for a non-static context.
1018 procedure Eval_Actual (N : Node_Id) is
1020 Check_Non_Static_Context (N);
1023 --------------------
1024 -- Eval_Allocator --
1025 --------------------
1027 -- Allocators are never static, so all we have to do is to do the
1028 -- check for a non-static context if an expression is present.
1030 procedure Eval_Allocator (N : Node_Id) is
1031 Expr : constant Node_Id := Expression (N);
1034 if Nkind (Expr) = N_Qualified_Expression then
1035 Check_Non_Static_Context (Expression (Expr));
1039 ------------------------
1040 -- Eval_Arithmetic_Op --
1041 ------------------------
1043 -- Arithmetic operations are static functions, so the result is static
1044 -- if both operands are static (RM 4.9(7), 4.9(20)).
1046 procedure Eval_Arithmetic_Op (N : Node_Id) is
1047 Left : constant Node_Id := Left_Opnd (N);
1048 Right : constant Node_Id := Right_Opnd (N);
1049 Ltype : constant Entity_Id := Etype (Left);
1050 Rtype : constant Entity_Id := Etype (Right);
1055 -- If not foldable we are done
1057 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1063 -- Fold for cases where both operands are of integer type
1065 if Is_Integer_Type (Ltype) and then Is_Integer_Type (Rtype) then
1067 Left_Int : constant Uint := Expr_Value (Left);
1068 Right_Int : constant Uint := Expr_Value (Right);
1075 Result := Left_Int + Right_Int;
1077 when N_Op_Subtract =>
1078 Result := Left_Int - Right_Int;
1080 when N_Op_Multiply =>
1083 (Num_Bits (Left_Int) + Num_Bits (Right_Int)))
1085 Result := Left_Int * Right_Int;
1092 -- The exception Constraint_Error is raised by integer
1093 -- division, rem and mod if the right operand is zero.
1095 if Right_Int = 0 then
1096 Apply_Compile_Time_Constraint_Error
1097 (N, "division by zero",
1103 Result := Left_Int / Right_Int;
1108 -- The exception Constraint_Error is raised by integer
1109 -- division, rem and mod if the right operand is zero.
1111 if Right_Int = 0 then
1112 Apply_Compile_Time_Constraint_Error
1113 (N, "mod with zero divisor",
1118 Result := Left_Int mod Right_Int;
1123 -- The exception Constraint_Error is raised by integer
1124 -- division, rem and mod if the right operand is zero.
1126 if Right_Int = 0 then
1127 Apply_Compile_Time_Constraint_Error
1128 (N, "rem with zero divisor",
1134 Result := Left_Int rem Right_Int;
1138 raise Program_Error;
1141 -- Adjust the result by the modulus if the type is a modular type
1143 if Is_Modular_Integer_Type (Ltype) then
1144 Result := Result mod Modulus (Ltype);
1146 -- For a signed integer type, check non-static overflow
1148 elsif (not Stat) and then Is_Signed_Integer_Type (Ltype) then
1150 BT : constant Entity_Id := Base_Type (Ltype);
1151 Lo : constant Uint := Expr_Value (Type_Low_Bound (BT));
1152 Hi : constant Uint := Expr_Value (Type_High_Bound (BT));
1154 if Result < Lo or else Result > Hi then
1155 Apply_Compile_Time_Constraint_Error
1156 (N, "value not in range of }?",
1157 CE_Overflow_Check_Failed,
1164 -- If we get here we can fold the result
1166 Fold_Uint (N, Result, Stat);
1169 -- Cases where at least one operand is a real. We handle the cases
1170 -- of both reals, or mixed/real integer cases (the latter happen
1171 -- only for divide and multiply, and the result is always real).
1173 elsif Is_Real_Type (Ltype) or else Is_Real_Type (Rtype) then
1180 if Is_Real_Type (Ltype) then
1181 Left_Real := Expr_Value_R (Left);
1183 Left_Real := UR_From_Uint (Expr_Value (Left));
1186 if Is_Real_Type (Rtype) then
1187 Right_Real := Expr_Value_R (Right);
1189 Right_Real := UR_From_Uint (Expr_Value (Right));
1192 if Nkind (N) = N_Op_Add then
1193 Result := Left_Real + Right_Real;
1195 elsif Nkind (N) = N_Op_Subtract then
1196 Result := Left_Real - Right_Real;
1198 elsif Nkind (N) = N_Op_Multiply then
1199 Result := Left_Real * Right_Real;
1201 else pragma Assert (Nkind (N) = N_Op_Divide);
1202 if UR_Is_Zero (Right_Real) then
1203 Apply_Compile_Time_Constraint_Error
1204 (N, "division by zero", CE_Divide_By_Zero);
1208 Result := Left_Real / Right_Real;
1211 Fold_Ureal (N, Result, Stat);
1214 end Eval_Arithmetic_Op;
1216 ----------------------------
1217 -- Eval_Character_Literal --
1218 ----------------------------
1220 -- Nothing to be done!
1222 procedure Eval_Character_Literal (N : Node_Id) is
1223 pragma Warnings (Off, N);
1226 end Eval_Character_Literal;
1232 -- Static function calls are either calls to predefined operators
1233 -- with static arguments, or calls to functions that rename a literal.
1234 -- Only the latter case is handled here, predefined operators are
1235 -- constant-folded elsewhere.
1236 -- If the function is itself inherited (see 7423-001) the literal of
1237 -- the parent type must be explicitly converted to the return type
1240 procedure Eval_Call (N : Node_Id) is
1241 Loc : constant Source_Ptr := Sloc (N);
1242 Typ : constant Entity_Id := Etype (N);
1246 if Nkind (N) = N_Function_Call
1247 and then No (Parameter_Associations (N))
1248 and then Is_Entity_Name (Name (N))
1249 and then Present (Alias (Entity (Name (N))))
1250 and then Is_Enumeration_Type (Base_Type (Typ))
1252 Lit := Alias (Entity (Name (N)));
1254 while Present (Alias (Lit)) loop
1258 if Ekind (Lit) = E_Enumeration_Literal then
1259 if Base_Type (Etype (Lit)) /= Base_Type (Typ) then
1261 (N, Convert_To (Typ, New_Occurrence_Of (Lit, Loc)));
1263 Rewrite (N, New_Occurrence_Of (Lit, Loc));
1271 ------------------------
1272 -- Eval_Concatenation --
1273 ------------------------
1275 -- Concatenation is a static function, so the result is static if
1276 -- both operands are static (RM 4.9(7), 4.9(21)).
1278 procedure Eval_Concatenation (N : Node_Id) is
1279 Left : constant Node_Id := Left_Opnd (N);
1280 Right : constant Node_Id := Right_Opnd (N);
1281 C_Typ : constant Entity_Id := Root_Type (Component_Type (Etype (N)));
1286 -- Concatenation is never static in Ada 83, so if Ada 83
1287 -- check operand non-static context
1289 if Ada_Version = Ada_83
1290 and then Comes_From_Source (N)
1292 Check_Non_Static_Context (Left);
1293 Check_Non_Static_Context (Right);
1297 -- If not foldable we are done. In principle concatenation that yields
1298 -- any string type is static (i.e. an array type of character types).
1299 -- However, character types can include enumeration literals, and
1300 -- concatenation in that case cannot be described by a literal, so we
1301 -- only consider the operation static if the result is an array of
1302 -- (a descendant of) a predefined character type.
1304 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1306 if (C_Typ = Standard_Character
1307 or else C_Typ = Standard_Wide_Character
1308 or else C_Typ = Standard_Wide_Wide_Character)
1313 Set_Is_Static_Expression (N, False);
1317 -- Compile time string concatenation
1319 -- ??? Note that operands that are aggregates can be marked as
1320 -- static, so we should attempt at a later stage to fold
1321 -- concatenations with such aggregates.
1324 Left_Str : constant Node_Id := Get_String_Val (Left);
1326 Right_Str : constant Node_Id := Get_String_Val (Right);
1329 -- Establish new string literal, and store left operand. We make
1330 -- sure to use the special Start_String that takes an operand if
1331 -- the left operand is a string literal. Since this is optimized
1332 -- in the case where that is the most recently created string
1333 -- literal, we ensure efficient time/space behavior for the
1334 -- case of a concatenation of a series of string literals.
1336 if Nkind (Left_Str) = N_String_Literal then
1337 Left_Len := String_Length (Strval (Left_Str));
1338 Start_String (Strval (Left_Str));
1341 Store_String_Char (UI_To_CC (Char_Literal_Value (Left_Str)));
1345 -- Now append the characters of the right operand
1347 if Nkind (Right_Str) = N_String_Literal then
1349 S : constant String_Id := Strval (Right_Str);
1352 for J in 1 .. String_Length (S) loop
1353 Store_String_Char (Get_String_Char (S, J));
1357 Store_String_Char (UI_To_CC (Char_Literal_Value (Right_Str)));
1360 Set_Is_Static_Expression (N, Stat);
1364 -- If left operand is the empty string, the result is the
1365 -- right operand, including its bounds if anomalous.
1368 and then Is_Array_Type (Etype (Right))
1369 and then Etype (Right) /= Any_String
1371 Set_Etype (N, Etype (Right));
1374 Fold_Str (N, End_String, True);
1377 end Eval_Concatenation;
1379 ---------------------------------
1380 -- Eval_Conditional_Expression --
1381 ---------------------------------
1383 -- This GNAT internal construct can never be statically folded, so the
1384 -- only required processing is to do the check for non-static context
1385 -- for the two expression operands.
1387 procedure Eval_Conditional_Expression (N : Node_Id) is
1388 Condition : constant Node_Id := First (Expressions (N));
1389 Then_Expr : constant Node_Id := Next (Condition);
1390 Else_Expr : constant Node_Id := Next (Then_Expr);
1393 Check_Non_Static_Context (Then_Expr);
1394 Check_Non_Static_Context (Else_Expr);
1395 end Eval_Conditional_Expression;
1397 ----------------------
1398 -- Eval_Entity_Name --
1399 ----------------------
1401 -- This procedure is used for identifiers and expanded names other than
1402 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
1403 -- static if they denote a static constant (RM 4.9(6)) or if the name
1404 -- denotes an enumeration literal (RM 4.9(22)).
1406 procedure Eval_Entity_Name (N : Node_Id) is
1407 Def_Id : constant Entity_Id := Entity (N);
1411 -- Enumeration literals are always considered to be constants
1412 -- and cannot raise constraint error (RM 4.9(22)).
1414 if Ekind (Def_Id) = E_Enumeration_Literal then
1415 Set_Is_Static_Expression (N);
1418 -- A name is static if it denotes a static constant (RM 4.9(5)), and
1419 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
1420 -- it does not violate 10.2.1(8) here, since this is not a variable.
1422 elsif Ekind (Def_Id) = E_Constant then
1424 -- Deferred constants must always be treated as nonstatic
1425 -- outside the scope of their full view.
1427 if Present (Full_View (Def_Id))
1428 and then not In_Open_Scopes (Scope (Def_Id))
1432 Val := Constant_Value (Def_Id);
1435 if Present (Val) then
1436 Set_Is_Static_Expression
1437 (N, Is_Static_Expression (Val)
1438 and then Is_Static_Subtype (Etype (Def_Id)));
1439 Set_Raises_Constraint_Error (N, Raises_Constraint_Error (Val));
1441 if not Is_Static_Expression (N)
1442 and then not Is_Generic_Type (Etype (N))
1444 Validate_Static_Object_Name (N);
1451 -- Fall through if the name is not static
1453 Validate_Static_Object_Name (N);
1454 end Eval_Entity_Name;
1456 ----------------------------
1457 -- Eval_Indexed_Component --
1458 ----------------------------
1460 -- Indexed components are never static, so we need to perform the check
1461 -- for non-static context on the index values. Then, we check if the
1462 -- value can be obtained at compile time, even though it is non-static.
1464 procedure Eval_Indexed_Component (N : Node_Id) is
1468 -- Check for non-static context on index values
1470 Expr := First (Expressions (N));
1471 while Present (Expr) loop
1472 Check_Non_Static_Context (Expr);
1476 -- If the indexed component appears in an object renaming declaration
1477 -- then we do not want to try to evaluate it, since in this case we
1478 -- need the identity of the array element.
1480 if Nkind (Parent (N)) = N_Object_Renaming_Declaration then
1483 -- Similarly if the indexed component appears as the prefix of an
1484 -- attribute we don't want to evaluate it, because at least for
1485 -- some cases of attributes we need the identify (e.g. Access, Size)
1487 elsif Nkind (Parent (N)) = N_Attribute_Reference then
1491 -- Note: there are other cases, such as the left side of an assignment,
1492 -- or an OUT parameter for a call, where the replacement results in the
1493 -- illegal use of a constant, But these cases are illegal in the first
1494 -- place, so the replacement, though silly, is harmless.
1496 -- Now see if this is a constant array reference
1498 if List_Length (Expressions (N)) = 1
1499 and then Is_Entity_Name (Prefix (N))
1500 and then Ekind (Entity (Prefix (N))) = E_Constant
1501 and then Present (Constant_Value (Entity (Prefix (N))))
1504 Loc : constant Source_Ptr := Sloc (N);
1505 Arr : constant Node_Id := Constant_Value (Entity (Prefix (N)));
1506 Sub : constant Node_Id := First (Expressions (N));
1512 -- Linear one's origin subscript value for array reference
1515 -- Lower bound of the first array index
1518 -- Value from constant array
1521 Atyp := Etype (Arr);
1523 if Is_Access_Type (Atyp) then
1524 Atyp := Designated_Type (Atyp);
1527 -- If we have an array type (we should have but perhaps there
1528 -- are error cases where this is not the case), then see if we
1529 -- can do a constant evaluation of the array reference.
1531 if Is_Array_Type (Atyp) then
1532 if Ekind (Atyp) = E_String_Literal_Subtype then
1533 Lbd := String_Literal_Low_Bound (Atyp);
1535 Lbd := Type_Low_Bound (Etype (First_Index (Atyp)));
1538 if Compile_Time_Known_Value (Sub)
1539 and then Nkind (Arr) = N_Aggregate
1540 and then Compile_Time_Known_Value (Lbd)
1541 and then Is_Discrete_Type (Component_Type (Atyp))
1543 Lin := UI_To_Int (Expr_Value (Sub) - Expr_Value (Lbd)) + 1;
1545 if List_Length (Expressions (Arr)) >= Lin then
1546 Elm := Pick (Expressions (Arr), Lin);
1548 -- If the resulting expression is compile time known,
1549 -- then we can rewrite the indexed component with this
1550 -- value, being sure to mark the result as non-static.
1551 -- We also reset the Sloc, in case this generates an
1552 -- error later on (e.g. 136'Access).
1554 if Compile_Time_Known_Value (Elm) then
1555 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
1556 Set_Is_Static_Expression (N, False);
1564 end Eval_Indexed_Component;
1566 --------------------------
1567 -- Eval_Integer_Literal --
1568 --------------------------
1570 -- Numeric literals are static (RM 4.9(1)), and have already been marked
1571 -- as static by the analyzer. The reason we did it that early is to allow
1572 -- the possibility of turning off the Is_Static_Expression flag after
1573 -- analysis, but before resolution, when integer literals are generated
1574 -- in the expander that do not correspond to static expressions.
1576 procedure Eval_Integer_Literal (N : Node_Id) is
1577 T : constant Entity_Id := Etype (N);
1579 function In_Any_Integer_Context return Boolean;
1580 -- If the literal is resolved with a specific type in a context
1581 -- where the expected type is Any_Integer, there are no range checks
1582 -- on the literal. By the time the literal is evaluated, it carries
1583 -- the type imposed by the enclosing expression, and we must recover
1584 -- the context to determine that Any_Integer is meant.
1586 ----------------------------
1587 -- To_Any_Integer_Context --
1588 ----------------------------
1590 function In_Any_Integer_Context return Boolean is
1591 Par : constant Node_Id := Parent (N);
1592 K : constant Node_Kind := Nkind (Par);
1595 -- Any_Integer also appears in digits specifications for real types,
1596 -- but those have bounds smaller that those of any integer base
1597 -- type, so we can safely ignore these cases.
1599 return K = N_Number_Declaration
1600 or else K = N_Attribute_Reference
1601 or else K = N_Attribute_Definition_Clause
1602 or else K = N_Modular_Type_Definition
1603 or else K = N_Signed_Integer_Type_Definition;
1604 end In_Any_Integer_Context;
1606 -- Start of processing for Eval_Integer_Literal
1610 -- If the literal appears in a non-expression context, then it is
1611 -- certainly appearing in a non-static context, so check it. This
1612 -- is actually a redundant check, since Check_Non_Static_Context
1613 -- would check it, but it seems worth while avoiding the call.
1615 if Nkind (Parent (N)) not in N_Subexpr
1616 and then not In_Any_Integer_Context
1618 Check_Non_Static_Context (N);
1621 -- Modular integer literals must be in their base range
1623 if Is_Modular_Integer_Type (T)
1624 and then Is_Out_Of_Range (N, Base_Type (T))
1628 end Eval_Integer_Literal;
1630 ---------------------
1631 -- Eval_Logical_Op --
1632 ---------------------
1634 -- Logical operations are static functions, so the result is potentially
1635 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
1637 procedure Eval_Logical_Op (N : Node_Id) is
1638 Left : constant Node_Id := Left_Opnd (N);
1639 Right : constant Node_Id := Right_Opnd (N);
1644 -- If not foldable we are done
1646 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1652 -- Compile time evaluation of logical operation
1655 Left_Int : constant Uint := Expr_Value (Left);
1656 Right_Int : constant Uint := Expr_Value (Right);
1659 if Is_Modular_Integer_Type (Etype (N)) then
1661 Left_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
1662 Right_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
1665 To_Bits (Left_Int, Left_Bits);
1666 To_Bits (Right_Int, Right_Bits);
1668 -- Note: should really be able to use array ops instead of
1669 -- these loops, but they weren't working at the time ???
1671 if Nkind (N) = N_Op_And then
1672 for J in Left_Bits'Range loop
1673 Left_Bits (J) := Left_Bits (J) and Right_Bits (J);
1676 elsif Nkind (N) = N_Op_Or then
1677 for J in Left_Bits'Range loop
1678 Left_Bits (J) := Left_Bits (J) or Right_Bits (J);
1682 pragma Assert (Nkind (N) = N_Op_Xor);
1684 for J in Left_Bits'Range loop
1685 Left_Bits (J) := Left_Bits (J) xor Right_Bits (J);
1689 Fold_Uint (N, From_Bits (Left_Bits, Etype (N)), Stat);
1693 pragma Assert (Is_Boolean_Type (Etype (N)));
1695 if Nkind (N) = N_Op_And then
1697 Test (Is_True (Left_Int) and then Is_True (Right_Int)), Stat);
1699 elsif Nkind (N) = N_Op_Or then
1701 Test (Is_True (Left_Int) or else Is_True (Right_Int)), Stat);
1704 pragma Assert (Nkind (N) = N_Op_Xor);
1706 Test (Is_True (Left_Int) xor Is_True (Right_Int)), Stat);
1710 end Eval_Logical_Op;
1712 ------------------------
1713 -- Eval_Membership_Op --
1714 ------------------------
1716 -- A membership test is potentially static if the expression is static,
1717 -- and the range is a potentially static range, or is a subtype mark
1718 -- denoting a static subtype (RM 4.9(12)).
1720 procedure Eval_Membership_Op (N : Node_Id) is
1721 Left : constant Node_Id := Left_Opnd (N);
1722 Right : constant Node_Id := Right_Opnd (N);
1731 -- Ignore if error in either operand, except to make sure that
1732 -- Any_Type is properly propagated to avoid junk cascaded errors.
1734 if Etype (Left) = Any_Type
1735 or else Etype (Right) = Any_Type
1737 Set_Etype (N, Any_Type);
1741 -- Case of right operand is a subtype name
1743 if Is_Entity_Name (Right) then
1744 Def_Id := Entity (Right);
1746 if (Is_Scalar_Type (Def_Id) or else Is_String_Type (Def_Id))
1747 and then Is_OK_Static_Subtype (Def_Id)
1749 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
1751 if not Fold or else not Stat then
1755 Check_Non_Static_Context (Left);
1759 -- For string membership tests we will check the length
1762 if not Is_String_Type (Def_Id) then
1763 Lo := Type_Low_Bound (Def_Id);
1764 Hi := Type_High_Bound (Def_Id);
1771 -- Case of right operand is a range
1774 if Is_Static_Range (Right) then
1775 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
1777 if not Fold or else not Stat then
1780 -- If one bound of range raises CE, then don't try to fold
1782 elsif not Is_OK_Static_Range (Right) then
1783 Check_Non_Static_Context (Left);
1788 Check_Non_Static_Context (Left);
1792 -- Here we know range is an OK static range
1794 Lo := Low_Bound (Right);
1795 Hi := High_Bound (Right);
1798 -- For strings we check that the length of the string expression is
1799 -- compatible with the string subtype if the subtype is constrained,
1800 -- or if unconstrained then the test is always true.
1802 if Is_String_Type (Etype (Right)) then
1803 if not Is_Constrained (Etype (Right)) then
1808 Typlen : constant Uint := String_Type_Len (Etype (Right));
1809 Strlen : constant Uint :=
1810 UI_From_Int (String_Length (Strval (Get_String_Val (Left))));
1812 Result := (Typlen = Strlen);
1816 -- Fold the membership test. We know we have a static range and Lo
1817 -- and Hi are set to the expressions for the end points of this range.
1819 elsif Is_Real_Type (Etype (Right)) then
1821 Leftval : constant Ureal := Expr_Value_R (Left);
1824 Result := Expr_Value_R (Lo) <= Leftval
1825 and then Leftval <= Expr_Value_R (Hi);
1830 Leftval : constant Uint := Expr_Value (Left);
1833 Result := Expr_Value (Lo) <= Leftval
1834 and then Leftval <= Expr_Value (Hi);
1838 if Nkind (N) = N_Not_In then
1839 Result := not Result;
1842 Fold_Uint (N, Test (Result), True);
1843 Warn_On_Known_Condition (N);
1844 end Eval_Membership_Op;
1846 ------------------------
1847 -- Eval_Named_Integer --
1848 ------------------------
1850 procedure Eval_Named_Integer (N : Node_Id) is
1853 Expr_Value (Expression (Declaration_Node (Entity (N)))), True);
1854 end Eval_Named_Integer;
1856 ---------------------
1857 -- Eval_Named_Real --
1858 ---------------------
1860 procedure Eval_Named_Real (N : Node_Id) is
1863 Expr_Value_R (Expression (Declaration_Node (Entity (N)))), True);
1864 end Eval_Named_Real;
1870 -- Exponentiation is a static functions, so the result is potentially
1871 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
1873 procedure Eval_Op_Expon (N : Node_Id) is
1874 Left : constant Node_Id := Left_Opnd (N);
1875 Right : constant Node_Id := Right_Opnd (N);
1880 -- If not foldable we are done
1882 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1888 -- Fold exponentiation operation
1891 Right_Int : constant Uint := Expr_Value (Right);
1896 if Is_Integer_Type (Etype (Left)) then
1898 Left_Int : constant Uint := Expr_Value (Left);
1902 -- Exponentiation of an integer raises the exception
1903 -- Constraint_Error for a negative exponent (RM 4.5.6)
1905 if Right_Int < 0 then
1906 Apply_Compile_Time_Constraint_Error
1907 (N, "integer exponent negative",
1908 CE_Range_Check_Failed,
1913 if OK_Bits (N, Num_Bits (Left_Int) * Right_Int) then
1914 Result := Left_Int ** Right_Int;
1919 if Is_Modular_Integer_Type (Etype (N)) then
1920 Result := Result mod Modulus (Etype (N));
1923 Fold_Uint (N, Result, Stat);
1931 Left_Real : constant Ureal := Expr_Value_R (Left);
1934 -- Cannot have a zero base with a negative exponent
1936 if UR_Is_Zero (Left_Real) then
1938 if Right_Int < 0 then
1939 Apply_Compile_Time_Constraint_Error
1940 (N, "zero ** negative integer",
1941 CE_Range_Check_Failed,
1945 Fold_Ureal (N, Ureal_0, Stat);
1949 Fold_Ureal (N, Left_Real ** Right_Int, Stat);
1960 -- The not operation is a static functions, so the result is potentially
1961 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
1963 procedure Eval_Op_Not (N : Node_Id) is
1964 Right : constant Node_Id := Right_Opnd (N);
1969 -- If not foldable we are done
1971 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
1977 -- Fold not operation
1980 Rint : constant Uint := Expr_Value (Right);
1981 Typ : constant Entity_Id := Etype (N);
1984 -- Negation is equivalent to subtracting from the modulus minus
1985 -- one. For a binary modulus this is equivalent to the ones-
1986 -- component of the original value. For non-binary modulus this
1987 -- is an arbitrary but consistent definition.
1989 if Is_Modular_Integer_Type (Typ) then
1990 Fold_Uint (N, Modulus (Typ) - 1 - Rint, Stat);
1993 pragma Assert (Is_Boolean_Type (Typ));
1994 Fold_Uint (N, Test (not Is_True (Rint)), Stat);
1997 Set_Is_Static_Expression (N, Stat);
2001 -------------------------------
2002 -- Eval_Qualified_Expression --
2003 -------------------------------
2005 -- A qualified expression is potentially static if its subtype mark denotes
2006 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2008 procedure Eval_Qualified_Expression (N : Node_Id) is
2009 Operand : constant Node_Id := Expression (N);
2010 Target_Type : constant Entity_Id := Entity (Subtype_Mark (N));
2017 -- Can only fold if target is string or scalar and subtype is static
2018 -- Also, do not fold if our parent is an allocator (this is because
2019 -- the qualified expression is really part of the syntactic structure
2020 -- of an allocator, and we do not want to end up with something that
2021 -- corresponds to "new 1" where the 1 is the result of folding a
2022 -- qualified expression).
2024 if not Is_Static_Subtype (Target_Type)
2025 or else Nkind (Parent (N)) = N_Allocator
2027 Check_Non_Static_Context (Operand);
2029 -- If operand is known to raise constraint_error, set the
2030 -- flag on the expression so it does not get optimized away.
2032 if Nkind (Operand) = N_Raise_Constraint_Error then
2033 Set_Raises_Constraint_Error (N);
2039 -- If not foldable we are done
2041 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
2046 -- Don't try fold if target type has constraint error bounds
2048 elsif not Is_OK_Static_Subtype (Target_Type) then
2049 Set_Raises_Constraint_Error (N);
2053 -- Here we will fold, save Print_In_Hex indication
2055 Hex := Nkind (Operand) = N_Integer_Literal
2056 and then Print_In_Hex (Operand);
2058 -- Fold the result of qualification
2060 if Is_Discrete_Type (Target_Type) then
2061 Fold_Uint (N, Expr_Value (Operand), Stat);
2063 -- Preserve Print_In_Hex indication
2065 if Hex and then Nkind (N) = N_Integer_Literal then
2066 Set_Print_In_Hex (N);
2069 elsif Is_Real_Type (Target_Type) then
2070 Fold_Ureal (N, Expr_Value_R (Operand), Stat);
2073 Fold_Str (N, Strval (Get_String_Val (Operand)), Stat);
2076 Set_Is_Static_Expression (N, False);
2078 Check_String_Literal_Length (N, Target_Type);
2084 -- The expression may be foldable but not static
2086 Set_Is_Static_Expression (N, Stat);
2088 if Is_Out_Of_Range (N, Etype (N)) then
2091 end Eval_Qualified_Expression;
2093 -----------------------
2094 -- Eval_Real_Literal --
2095 -----------------------
2097 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2098 -- as static by the analyzer. The reason we did it that early is to allow
2099 -- the possibility of turning off the Is_Static_Expression flag after
2100 -- analysis, but before resolution, when integer literals are generated
2101 -- in the expander that do not correspond to static expressions.
2103 procedure Eval_Real_Literal (N : Node_Id) is
2105 -- If the literal appears in a non-expression context, then it is
2106 -- certainly appearing in a non-static context, so check it.
2108 if Nkind (Parent (N)) not in N_Subexpr then
2109 Check_Non_Static_Context (N);
2112 end Eval_Real_Literal;
2114 ------------------------
2115 -- Eval_Relational_Op --
2116 ------------------------
2118 -- Relational operations are static functions, so the result is static
2119 -- if both operands are static (RM 4.9(7), 4.9(20)).
2121 procedure Eval_Relational_Op (N : Node_Id) is
2122 Left : constant Node_Id := Left_Opnd (N);
2123 Right : constant Node_Id := Right_Opnd (N);
2124 Typ : constant Entity_Id := Etype (Left);
2130 -- One special case to deal with first. If we can tell that
2131 -- the result will be false because the lengths of one or
2132 -- more index subtypes are compile time known and different,
2133 -- then we can replace the entire result by False. We only
2134 -- do this for one dimensional arrays, because the case of
2135 -- multi-dimensional arrays is rare and too much trouble!
2137 if Is_Array_Type (Typ)
2138 and then Number_Dimensions (Typ) = 1
2139 and then (Nkind (N) = N_Op_Eq
2140 or else Nkind (N) = N_Op_Ne)
2142 if Raises_Constraint_Error (Left)
2143 or else Raises_Constraint_Error (Right)
2149 procedure Get_Static_Length (Op : Node_Id; Len : out Uint);
2150 -- If Op is an expression for a constrained array with a
2151 -- known at compile time length, then Len is set to this
2152 -- (non-negative length). Otherwise Len is set to minus 1.
2154 -----------------------
2155 -- Get_Static_Length --
2156 -----------------------
2158 procedure Get_Static_Length (Op : Node_Id; Len : out Uint) is
2162 if Nkind (Op) = N_String_Literal then
2163 Len := UI_From_Int (String_Length (Strval (Op)));
2165 elsif not Is_Constrained (Etype (Op)) then
2166 Len := Uint_Minus_1;
2169 T := Etype (First_Index (Etype (Op)));
2171 if Is_Discrete_Type (T)
2173 Compile_Time_Known_Value (Type_Low_Bound (T))
2175 Compile_Time_Known_Value (Type_High_Bound (T))
2177 Len := UI_Max (Uint_0,
2178 Expr_Value (Type_High_Bound (T)) -
2179 Expr_Value (Type_Low_Bound (T)) + 1);
2181 Len := Uint_Minus_1;
2184 end Get_Static_Length;
2190 Get_Static_Length (Left, Len_L);
2191 Get_Static_Length (Right, Len_R);
2193 if Len_L /= Uint_Minus_1
2194 and then Len_R /= Uint_Minus_1
2195 and then Len_L /= Len_R
2197 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2198 Warn_On_Known_Condition (N);
2204 -- Can only fold if type is scalar (don't fold string ops)
2206 if not Is_Scalar_Type (Typ) then
2207 Check_Non_Static_Context (Left);
2208 Check_Non_Static_Context (Right);
2212 -- If not foldable we are done
2214 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2220 -- Integer and Enumeration (discrete) type cases
2222 if Is_Discrete_Type (Typ) then
2224 Left_Int : constant Uint := Expr_Value (Left);
2225 Right_Int : constant Uint := Expr_Value (Right);
2229 when N_Op_Eq => Result := Left_Int = Right_Int;
2230 when N_Op_Ne => Result := Left_Int /= Right_Int;
2231 when N_Op_Lt => Result := Left_Int < Right_Int;
2232 when N_Op_Le => Result := Left_Int <= Right_Int;
2233 when N_Op_Gt => Result := Left_Int > Right_Int;
2234 when N_Op_Ge => Result := Left_Int >= Right_Int;
2237 raise Program_Error;
2240 Fold_Uint (N, Test (Result), Stat);
2246 pragma Assert (Is_Real_Type (Typ));
2249 Left_Real : constant Ureal := Expr_Value_R (Left);
2250 Right_Real : constant Ureal := Expr_Value_R (Right);
2254 when N_Op_Eq => Result := (Left_Real = Right_Real);
2255 when N_Op_Ne => Result := (Left_Real /= Right_Real);
2256 when N_Op_Lt => Result := (Left_Real < Right_Real);
2257 when N_Op_Le => Result := (Left_Real <= Right_Real);
2258 when N_Op_Gt => Result := (Left_Real > Right_Real);
2259 when N_Op_Ge => Result := (Left_Real >= Right_Real);
2262 raise Program_Error;
2265 Fold_Uint (N, Test (Result), Stat);
2269 Warn_On_Known_Condition (N);
2270 end Eval_Relational_Op;
2276 -- Shift operations are intrinsic operations that can never be static,
2277 -- so the only processing required is to perform the required check for
2278 -- a non static context for the two operands.
2280 -- Actually we could do some compile time evaluation here some time ???
2282 procedure Eval_Shift (N : Node_Id) is
2284 Check_Non_Static_Context (Left_Opnd (N));
2285 Check_Non_Static_Context (Right_Opnd (N));
2288 ------------------------
2289 -- Eval_Short_Circuit --
2290 ------------------------
2292 -- A short circuit operation is potentially static if both operands
2293 -- are potentially static (RM 4.9 (13))
2295 procedure Eval_Short_Circuit (N : Node_Id) is
2296 Kind : constant Node_Kind := Nkind (N);
2297 Left : constant Node_Id := Left_Opnd (N);
2298 Right : constant Node_Id := Right_Opnd (N);
2300 Rstat : constant Boolean :=
2301 Is_Static_Expression (Left)
2302 and then Is_Static_Expression (Right);
2305 -- Short circuit operations are never static in Ada 83
2307 if Ada_Version = Ada_83
2308 and then Comes_From_Source (N)
2310 Check_Non_Static_Context (Left);
2311 Check_Non_Static_Context (Right);
2315 -- Now look at the operands, we can't quite use the normal call to
2316 -- Test_Expression_Is_Foldable here because short circuit operations
2317 -- are a special case, they can still be foldable, even if the right
2318 -- operand raises constraint error.
2320 -- If either operand is Any_Type, just propagate to result and
2321 -- do not try to fold, this prevents cascaded errors.
2323 if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
2324 Set_Etype (N, Any_Type);
2327 -- If left operand raises constraint error, then replace node N with
2328 -- the raise constraint error node, and we are obviously not foldable.
2329 -- Is_Static_Expression is set from the two operands in the normal way,
2330 -- and we check the right operand if it is in a non-static context.
2332 elsif Raises_Constraint_Error (Left) then
2334 Check_Non_Static_Context (Right);
2337 Rewrite_In_Raise_CE (N, Left);
2338 Set_Is_Static_Expression (N, Rstat);
2341 -- If the result is not static, then we won't in any case fold
2343 elsif not Rstat then
2344 Check_Non_Static_Context (Left);
2345 Check_Non_Static_Context (Right);
2349 -- Here the result is static, note that, unlike the normal processing
2350 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
2351 -- the right operand raises constraint error, that's because it is not
2352 -- significant if the left operand is decisive.
2354 Set_Is_Static_Expression (N);
2356 -- It does not matter if the right operand raises constraint error if
2357 -- it will not be evaluated. So deal specially with the cases where
2358 -- the right operand is not evaluated. Note that we will fold these
2359 -- cases even if the right operand is non-static, which is fine, but
2360 -- of course in these cases the result is not potentially static.
2362 Left_Int := Expr_Value (Left);
2364 if (Kind = N_And_Then and then Is_False (Left_Int))
2365 or else (Kind = N_Or_Else and Is_True (Left_Int))
2367 Fold_Uint (N, Left_Int, Rstat);
2371 -- If first operand not decisive, then it does matter if the right
2372 -- operand raises constraint error, since it will be evaluated, so
2373 -- we simply replace the node with the right operand. Note that this
2374 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
2375 -- (both are set to True in Right).
2377 if Raises_Constraint_Error (Right) then
2378 Rewrite_In_Raise_CE (N, Right);
2379 Check_Non_Static_Context (Left);
2383 -- Otherwise the result depends on the right operand
2385 Fold_Uint (N, Expr_Value (Right), Rstat);
2387 end Eval_Short_Circuit;
2393 -- Slices can never be static, so the only processing required is to
2394 -- check for non-static context if an explicit range is given.
2396 procedure Eval_Slice (N : Node_Id) is
2397 Drange : constant Node_Id := Discrete_Range (N);
2400 if Nkind (Drange) = N_Range then
2401 Check_Non_Static_Context (Low_Bound (Drange));
2402 Check_Non_Static_Context (High_Bound (Drange));
2406 -------------------------
2407 -- Eval_String_Literal --
2408 -------------------------
2410 procedure Eval_String_Literal (N : Node_Id) is
2411 Typ : constant Entity_Id := Etype (N);
2412 Bas : constant Entity_Id := Base_Type (Typ);
2418 -- Nothing to do if error type (handles cases like default expressions
2419 -- or generics where we have not yet fully resolved the type)
2421 if Bas = Any_Type or else Bas = Any_String then
2425 -- String literals are static if the subtype is static (RM 4.9(2)), so
2426 -- reset the static expression flag (it was set unconditionally in
2427 -- Analyze_String_Literal) if the subtype is non-static. We tell if
2428 -- the subtype is static by looking at the lower bound.
2430 if Ekind (Typ) = E_String_Literal_Subtype then
2431 if not Is_OK_Static_Expression (String_Literal_Low_Bound (Typ)) then
2432 Set_Is_Static_Expression (N, False);
2436 -- Here if Etype of string literal is normal Etype (not yet possible,
2437 -- but may be possible in future!)
2439 elsif not Is_OK_Static_Expression
2440 (Type_Low_Bound (Etype (First_Index (Typ))))
2442 Set_Is_Static_Expression (N, False);
2446 -- If original node was a type conversion, then result if non-static
2448 if Nkind (Original_Node (N)) = N_Type_Conversion then
2449 Set_Is_Static_Expression (N, False);
2453 -- Test for illegal Ada 95 cases. A string literal is illegal in
2454 -- Ada 95 if its bounds are outside the index base type and this
2455 -- index type is static. This can happen in only two ways. Either
2456 -- the string literal is too long, or it is null, and the lower
2457 -- bound is type'First. In either case it is the upper bound that
2458 -- is out of range of the index type.
2460 if Ada_Version >= Ada_95 then
2461 if Root_Type (Bas) = Standard_String
2463 Root_Type (Bas) = Standard_Wide_String
2465 Xtp := Standard_Positive;
2467 Xtp := Etype (First_Index (Bas));
2470 if Ekind (Typ) = E_String_Literal_Subtype then
2471 Lo := String_Literal_Low_Bound (Typ);
2473 Lo := Type_Low_Bound (Etype (First_Index (Typ)));
2476 Len := String_Length (Strval (N));
2478 if UI_From_Int (Len) > String_Type_Len (Bas) then
2479 Apply_Compile_Time_Constraint_Error
2480 (N, "string literal too long for}", CE_Length_Check_Failed,
2482 Typ => First_Subtype (Bas));
2485 and then not Is_Generic_Type (Xtp)
2487 Expr_Value (Lo) = Expr_Value (Type_Low_Bound (Base_Type (Xtp)))
2489 Apply_Compile_Time_Constraint_Error
2490 (N, "null string literal not allowed for}",
2491 CE_Length_Check_Failed,
2493 Typ => First_Subtype (Bas));
2496 end Eval_String_Literal;
2498 --------------------------
2499 -- Eval_Type_Conversion --
2500 --------------------------
2502 -- A type conversion is potentially static if its subtype mark is for a
2503 -- static scalar subtype, and its operand expression is potentially static
2506 procedure Eval_Type_Conversion (N : Node_Id) is
2507 Operand : constant Node_Id := Expression (N);
2508 Source_Type : constant Entity_Id := Etype (Operand);
2509 Target_Type : constant Entity_Id := Etype (N);
2514 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean;
2515 -- Returns true if type T is an integer type, or if it is a
2516 -- fixed-point type to be treated as an integer (i.e. the flag
2517 -- Conversion_OK is set on the conversion node).
2519 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean;
2520 -- Returns true if type T is a floating-point type, or if it is a
2521 -- fixed-point type that is not to be treated as an integer (i.e. the
2522 -- flag Conversion_OK is not set on the conversion node).
2524 ------------------------------
2525 -- To_Be_Treated_As_Integer --
2526 ------------------------------
2528 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean is
2532 or else (Is_Fixed_Point_Type (T) and then Conversion_OK (N));
2533 end To_Be_Treated_As_Integer;
2535 ---------------------------
2536 -- To_Be_Treated_As_Real --
2537 ---------------------------
2539 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean is
2542 Is_Floating_Point_Type (T)
2543 or else (Is_Fixed_Point_Type (T) and then not Conversion_OK (N));
2544 end To_Be_Treated_As_Real;
2546 -- Start of processing for Eval_Type_Conversion
2549 -- Cannot fold if target type is non-static or if semantic error
2551 if not Is_Static_Subtype (Target_Type) then
2552 Check_Non_Static_Context (Operand);
2555 elsif Error_Posted (N) then
2559 -- If not foldable we are done
2561 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
2566 -- Don't try fold if target type has constraint error bounds
2568 elsif not Is_OK_Static_Subtype (Target_Type) then
2569 Set_Raises_Constraint_Error (N);
2573 -- Remaining processing depends on operand types. Note that in the
2574 -- following type test, fixed-point counts as real unless the flag
2575 -- Conversion_OK is set, in which case it counts as integer.
2577 -- Fold conversion, case of string type. The result is not static
2579 if Is_String_Type (Target_Type) then
2580 Fold_Str (N, Strval (Get_String_Val (Operand)), False);
2584 -- Fold conversion, case of integer target type
2586 elsif To_Be_Treated_As_Integer (Target_Type) then
2591 -- Integer to integer conversion
2593 if To_Be_Treated_As_Integer (Source_Type) then
2594 Result := Expr_Value (Operand);
2596 -- Real to integer conversion
2599 Result := UR_To_Uint (Expr_Value_R (Operand));
2602 -- If fixed-point type (Conversion_OK must be set), then the
2603 -- result is logically an integer, but we must replace the
2604 -- conversion with the corresponding real literal, since the
2605 -- type from a semantic point of view is still fixed-point.
2607 if Is_Fixed_Point_Type (Target_Type) then
2609 (N, UR_From_Uint (Result) * Small_Value (Target_Type), Stat);
2611 -- Otherwise result is integer literal
2614 Fold_Uint (N, Result, Stat);
2618 -- Fold conversion, case of real target type
2620 elsif To_Be_Treated_As_Real (Target_Type) then
2625 if To_Be_Treated_As_Real (Source_Type) then
2626 Result := Expr_Value_R (Operand);
2628 Result := UR_From_Uint (Expr_Value (Operand));
2631 Fold_Ureal (N, Result, Stat);
2634 -- Enumeration types
2637 Fold_Uint (N, Expr_Value (Operand), Stat);
2640 if Is_Out_Of_Range (N, Etype (N)) then
2644 end Eval_Type_Conversion;
2650 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
2651 -- are potentially static if the operand is potentially static (RM 4.9(7))
2653 procedure Eval_Unary_Op (N : Node_Id) is
2654 Right : constant Node_Id := Right_Opnd (N);
2659 -- If not foldable we are done
2661 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
2667 -- Fold for integer case
2669 if Is_Integer_Type (Etype (N)) then
2671 Rint : constant Uint := Expr_Value (Right);
2675 -- In the case of modular unary plus and abs there is no need
2676 -- to adjust the result of the operation since if the original
2677 -- operand was in bounds the result will be in the bounds of the
2678 -- modular type. However, in the case of modular unary minus the
2679 -- result may go out of the bounds of the modular type and needs
2682 if Nkind (N) = N_Op_Plus then
2685 elsif Nkind (N) = N_Op_Minus then
2686 if Is_Modular_Integer_Type (Etype (N)) then
2687 Result := (-Rint) mod Modulus (Etype (N));
2693 pragma Assert (Nkind (N) = N_Op_Abs);
2697 Fold_Uint (N, Result, Stat);
2700 -- Fold for real case
2702 elsif Is_Real_Type (Etype (N)) then
2704 Rreal : constant Ureal := Expr_Value_R (Right);
2708 if Nkind (N) = N_Op_Plus then
2711 elsif Nkind (N) = N_Op_Minus then
2712 Result := UR_Negate (Rreal);
2715 pragma Assert (Nkind (N) = N_Op_Abs);
2716 Result := abs Rreal;
2719 Fold_Ureal (N, Result, Stat);
2724 -------------------------------
2725 -- Eval_Unchecked_Conversion --
2726 -------------------------------
2728 -- Unchecked conversions can never be static, so the only required
2729 -- processing is to check for a non-static context for the operand.
2731 procedure Eval_Unchecked_Conversion (N : Node_Id) is
2733 Check_Non_Static_Context (Expression (N));
2734 end Eval_Unchecked_Conversion;
2736 --------------------
2737 -- Expr_Rep_Value --
2738 --------------------
2740 function Expr_Rep_Value (N : Node_Id) return Uint is
2741 Kind : constant Node_Kind := Nkind (N);
2745 if Is_Entity_Name (N) then
2748 -- An enumeration literal that was either in the source or
2749 -- created as a result of static evaluation.
2751 if Ekind (Ent) = E_Enumeration_Literal then
2752 return Enumeration_Rep (Ent);
2754 -- A user defined static constant
2757 pragma Assert (Ekind (Ent) = E_Constant);
2758 return Expr_Rep_Value (Constant_Value (Ent));
2761 -- An integer literal that was either in the source or created
2762 -- as a result of static evaluation.
2764 elsif Kind = N_Integer_Literal then
2767 -- A real literal for a fixed-point type. This must be the fixed-point
2768 -- case, either the literal is of a fixed-point type, or it is a bound
2769 -- of a fixed-point type, with type universal real. In either case we
2770 -- obtain the desired value from Corresponding_Integer_Value.
2772 elsif Kind = N_Real_Literal then
2773 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
2774 return Corresponding_Integer_Value (N);
2776 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
2778 elsif Kind = N_Attribute_Reference
2779 and then Attribute_Name (N) = Name_Null_Parameter
2783 -- Otherwise must be character literal
2786 pragma Assert (Kind = N_Character_Literal);
2789 -- Since Character literals of type Standard.Character don't
2790 -- have any defining character literals built for them, they
2791 -- do not have their Entity set, so just use their Char
2792 -- code. Otherwise for user-defined character literals use
2793 -- their Pos value as usual which is the same as the Rep value.
2796 return Char_Literal_Value (N);
2798 return Enumeration_Rep (Ent);
2807 function Expr_Value (N : Node_Id) return Uint is
2808 Kind : constant Node_Kind := Nkind (N);
2809 CV_Ent : CV_Entry renames CV_Cache (Nat (N) mod CV_Cache_Size);
2814 -- If already in cache, then we know it's compile time known and
2815 -- we can return the value that was previously stored in the cache
2816 -- since compile time known values cannot change :-)
2818 if CV_Ent.N = N then
2822 -- Otherwise proceed to test value
2824 if Is_Entity_Name (N) then
2827 -- An enumeration literal that was either in the source or
2828 -- created as a result of static evaluation.
2830 if Ekind (Ent) = E_Enumeration_Literal then
2831 Val := Enumeration_Pos (Ent);
2833 -- A user defined static constant
2836 pragma Assert (Ekind (Ent) = E_Constant);
2837 Val := Expr_Value (Constant_Value (Ent));
2840 -- An integer literal that was either in the source or created
2841 -- as a result of static evaluation.
2843 elsif Kind = N_Integer_Literal then
2846 -- A real literal for a fixed-point type. This must be the fixed-point
2847 -- case, either the literal is of a fixed-point type, or it is a bound
2848 -- of a fixed-point type, with type universal real. In either case we
2849 -- obtain the desired value from Corresponding_Integer_Value.
2851 elsif Kind = N_Real_Literal then
2853 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
2854 Val := Corresponding_Integer_Value (N);
2856 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
2858 elsif Kind = N_Attribute_Reference
2859 and then Attribute_Name (N) = Name_Null_Parameter
2863 -- Otherwise must be character literal
2866 pragma Assert (Kind = N_Character_Literal);
2869 -- Since Character literals of type Standard.Character don't
2870 -- have any defining character literals built for them, they
2871 -- do not have their Entity set, so just use their Char
2872 -- code. Otherwise for user-defined character literals use
2873 -- their Pos value as usual.
2876 Val := Char_Literal_Value (N);
2878 Val := Enumeration_Pos (Ent);
2882 -- Come here with Val set to value to be returned, set cache
2893 function Expr_Value_E (N : Node_Id) return Entity_Id is
2894 Ent : constant Entity_Id := Entity (N);
2897 if Ekind (Ent) = E_Enumeration_Literal then
2900 pragma Assert (Ekind (Ent) = E_Constant);
2901 return Expr_Value_E (Constant_Value (Ent));
2909 function Expr_Value_R (N : Node_Id) return Ureal is
2910 Kind : constant Node_Kind := Nkind (N);
2915 if Kind = N_Real_Literal then
2918 elsif Kind = N_Identifier or else Kind = N_Expanded_Name then
2920 pragma Assert (Ekind (Ent) = E_Constant);
2921 return Expr_Value_R (Constant_Value (Ent));
2923 elsif Kind = N_Integer_Literal then
2924 return UR_From_Uint (Expr_Value (N));
2926 -- Strange case of VAX literals, which are at this stage transformed
2927 -- into Vax_Type!x_To_y(IEEE_Literal). See Expand_N_Real_Literal in
2928 -- Exp_Vfpt for further details.
2930 elsif Vax_Float (Etype (N))
2931 and then Nkind (N) = N_Unchecked_Type_Conversion
2933 Expr := Expression (N);
2935 if Nkind (Expr) = N_Function_Call
2936 and then Present (Parameter_Associations (Expr))
2938 Expr := First (Parameter_Associations (Expr));
2940 if Nkind (Expr) = N_Real_Literal then
2941 return Realval (Expr);
2945 -- Peculiar VMS case, if we have xxx'Null_Parameter, return 0.0
2947 elsif Kind = N_Attribute_Reference
2948 and then Attribute_Name (N) = Name_Null_Parameter
2953 -- If we fall through, we have a node that cannot be interepreted
2954 -- as a compile time constant. That is definitely an error.
2956 raise Program_Error;
2963 function Expr_Value_S (N : Node_Id) return Node_Id is
2965 if Nkind (N) = N_String_Literal then
2968 pragma Assert (Ekind (Entity (N)) = E_Constant);
2969 return Expr_Value_S (Constant_Value (Entity (N)));
2973 --------------------------
2974 -- Flag_Non_Static_Expr --
2975 --------------------------
2977 procedure Flag_Non_Static_Expr (Msg : String; Expr : Node_Id) is
2979 if Error_Posted (Expr) and then not All_Errors_Mode then
2982 Error_Msg_F (Msg, Expr);
2983 Why_Not_Static (Expr);
2985 end Flag_Non_Static_Expr;
2991 procedure Fold_Str (N : Node_Id; Val : String_Id; Static : Boolean) is
2992 Loc : constant Source_Ptr := Sloc (N);
2993 Typ : constant Entity_Id := Etype (N);
2996 Rewrite (N, Make_String_Literal (Loc, Strval => Val));
2998 -- We now have the literal with the right value, both the actual type
2999 -- and the expected type of this literal are taken from the expression
3000 -- that was evaluated.
3003 Set_Is_Static_Expression (N, Static);
3012 procedure Fold_Uint (N : Node_Id; Val : Uint; Static : Boolean) is
3013 Loc : constant Source_Ptr := Sloc (N);
3014 Typ : Entity_Id := Etype (N);
3018 -- If we are folding a named number, retain the entity in the
3019 -- literal, for ASIS use.
3021 if Is_Entity_Name (N)
3022 and then Ekind (Entity (N)) = E_Named_Integer
3029 if Is_Private_Type (Typ) then
3030 Typ := Full_View (Typ);
3033 -- For a result of type integer, subsitute an N_Integer_Literal node
3034 -- for the result of the compile time evaluation of the expression.
3036 if Is_Integer_Type (Typ) then
3037 Rewrite (N, Make_Integer_Literal (Loc, Val));
3038 Set_Original_Entity (N, Ent);
3040 -- Otherwise we have an enumeration type, and we substitute either
3041 -- an N_Identifier or N_Character_Literal to represent the enumeration
3042 -- literal corresponding to the given value, which must always be in
3043 -- range, because appropriate tests have already been made for this.
3045 else pragma Assert (Is_Enumeration_Type (Typ));
3046 Rewrite (N, Get_Enum_Lit_From_Pos (Etype (N), Val, Loc));
3049 -- We now have the literal with the right value, both the actual type
3050 -- and the expected type of this literal are taken from the expression
3051 -- that was evaluated.
3054 Set_Is_Static_Expression (N, Static);
3063 procedure Fold_Ureal (N : Node_Id; Val : Ureal; Static : Boolean) is
3064 Loc : constant Source_Ptr := Sloc (N);
3065 Typ : constant Entity_Id := Etype (N);
3069 -- If we are folding a named number, retain the entity in the
3070 -- literal, for ASIS use.
3072 if Is_Entity_Name (N)
3073 and then Ekind (Entity (N)) = E_Named_Real
3080 Rewrite (N, Make_Real_Literal (Loc, Realval => Val));
3081 Set_Original_Entity (N, Ent);
3083 -- Both the actual and expected type comes from the original expression
3086 Set_Is_Static_Expression (N, Static);
3095 function From_Bits (B : Bits; T : Entity_Id) return Uint is
3099 for J in 0 .. B'Last loop
3105 if Non_Binary_Modulus (T) then
3106 V := V mod Modulus (T);
3112 --------------------
3113 -- Get_String_Val --
3114 --------------------
3116 function Get_String_Val (N : Node_Id) return Node_Id is
3118 if Nkind (N) = N_String_Literal then
3121 elsif Nkind (N) = N_Character_Literal then
3125 pragma Assert (Is_Entity_Name (N));
3126 return Get_String_Val (Constant_Value (Entity (N)));
3134 procedure Initialize is
3136 CV_Cache := (others => (Node_High_Bound, Uint_0));
3139 --------------------
3140 -- In_Subrange_Of --
3141 --------------------
3143 function In_Subrange_Of
3146 Fixed_Int : Boolean := False) return Boolean
3155 if T1 = T2 or else Is_Subtype_Of (T1, T2) then
3158 -- Never in range if both types are not scalar. Don't know if this can
3159 -- actually happen, but just in case.
3161 elsif not Is_Scalar_Type (T1) or else not Is_Scalar_Type (T1) then
3165 L1 := Type_Low_Bound (T1);
3166 H1 := Type_High_Bound (T1);
3168 L2 := Type_Low_Bound (T2);
3169 H2 := Type_High_Bound (T2);
3171 -- Check bounds to see if comparison possible at compile time
3173 if Compile_Time_Compare (L1, L2) in Compare_GE
3175 Compile_Time_Compare (H1, H2) in Compare_LE
3180 -- If bounds not comparable at compile time, then the bounds of T2
3181 -- must be compile time known or we cannot answer the query.
3183 if not Compile_Time_Known_Value (L2)
3184 or else not Compile_Time_Known_Value (H2)
3189 -- If the bounds of T1 are know at compile time then use these
3190 -- ones, otherwise use the bounds of the base type (which are of
3191 -- course always static).
3193 if not Compile_Time_Known_Value (L1) then
3194 L1 := Type_Low_Bound (Base_Type (T1));
3197 if not Compile_Time_Known_Value (H1) then
3198 H1 := Type_High_Bound (Base_Type (T1));
3201 -- Fixed point types should be considered as such only if
3202 -- flag Fixed_Int is set to False.
3204 if Is_Floating_Point_Type (T1) or else Is_Floating_Point_Type (T2)
3205 or else (Is_Fixed_Point_Type (T1) and then not Fixed_Int)
3206 or else (Is_Fixed_Point_Type (T2) and then not Fixed_Int)
3209 Expr_Value_R (L2) <= Expr_Value_R (L1)
3211 Expr_Value_R (H2) >= Expr_Value_R (H1);
3215 Expr_Value (L2) <= Expr_Value (L1)
3217 Expr_Value (H2) >= Expr_Value (H1);
3222 -- If any exception occurs, it means that we have some bug in the compiler
3223 -- possibly triggered by a previous error, or by some unforseen peculiar
3224 -- occurrence. However, this is only an optimization attempt, so there is
3225 -- really no point in crashing the compiler. Instead we just decide, too
3226 -- bad, we can't figure out the answer in this case after all.
3231 -- Debug flag K disables this behavior (useful for debugging)
3233 if Debug_Flag_K then
3244 function Is_In_Range
3247 Fixed_Int : Boolean := False;
3248 Int_Real : Boolean := False) return Boolean
3254 -- Universal types have no range limits, so always in range
3256 if Typ = Universal_Integer or else Typ = Universal_Real then
3259 -- Never in range if not scalar type. Don't know if this can
3260 -- actually happen, but our spec allows it, so we must check!
3262 elsif not Is_Scalar_Type (Typ) then
3265 -- Never in range unless we have a compile time known value
3267 elsif not Compile_Time_Known_Value (N) then
3272 Lo : constant Node_Id := Type_Low_Bound (Typ);
3273 Hi : constant Node_Id := Type_High_Bound (Typ);
3274 LB_Known : constant Boolean := Compile_Time_Known_Value (Lo);
3275 UB_Known : constant Boolean := Compile_Time_Known_Value (Hi);
3278 -- Fixed point types should be considered as such only in
3279 -- flag Fixed_Int is set to False.
3281 if Is_Floating_Point_Type (Typ)
3282 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
3285 Valr := Expr_Value_R (N);
3287 if LB_Known and then Valr >= Expr_Value_R (Lo)
3288 and then UB_Known and then Valr <= Expr_Value_R (Hi)
3296 Val := Expr_Value (N);
3298 if LB_Known and then Val >= Expr_Value (Lo)
3299 and then UB_Known and then Val <= Expr_Value (Hi)
3314 function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
3315 Typ : constant Entity_Id := Etype (Lo);
3318 if not Compile_Time_Known_Value (Lo)
3319 or else not Compile_Time_Known_Value (Hi)
3324 if Is_Discrete_Type (Typ) then
3325 return Expr_Value (Lo) > Expr_Value (Hi);
3328 pragma Assert (Is_Real_Type (Typ));
3329 return Expr_Value_R (Lo) > Expr_Value_R (Hi);
3333 -----------------------------
3334 -- Is_OK_Static_Expression --
3335 -----------------------------
3337 function Is_OK_Static_Expression (N : Node_Id) return Boolean is
3339 return Is_Static_Expression (N)
3340 and then not Raises_Constraint_Error (N);
3341 end Is_OK_Static_Expression;
3343 ------------------------
3344 -- Is_OK_Static_Range --
3345 ------------------------
3347 -- A static range is a range whose bounds are static expressions, or a
3348 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
3349 -- We have already converted range attribute references, so we get the
3350 -- "or" part of this rule without needing a special test.
3352 function Is_OK_Static_Range (N : Node_Id) return Boolean is
3354 return Is_OK_Static_Expression (Low_Bound (N))
3355 and then Is_OK_Static_Expression (High_Bound (N));
3356 end Is_OK_Static_Range;
3358 --------------------------
3359 -- Is_OK_Static_Subtype --
3360 --------------------------
3362 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
3363 -- where neither bound raises constraint error when evaluated.
3365 function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean is
3366 Base_T : constant Entity_Id := Base_Type (Typ);
3367 Anc_Subt : Entity_Id;
3370 -- First a quick check on the non static subtype flag. As described
3371 -- in further detail in Einfo, this flag is not decisive in all cases,
3372 -- but if it is set, then the subtype is definitely non-static.
3374 if Is_Non_Static_Subtype (Typ) then
3378 Anc_Subt := Ancestor_Subtype (Typ);
3380 if Anc_Subt = Empty then
3384 if Is_Generic_Type (Root_Type (Base_T))
3385 or else Is_Generic_Actual_Type (Base_T)
3391 elsif Is_String_Type (Typ) then
3393 Ekind (Typ) = E_String_Literal_Subtype
3395 (Is_OK_Static_Subtype (Component_Type (Typ))
3396 and then Is_OK_Static_Subtype (Etype (First_Index (Typ))));
3400 elsif Is_Scalar_Type (Typ) then
3401 if Base_T = Typ then
3405 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so
3406 -- use Get_Type_Low,High_Bound.
3408 return Is_OK_Static_Subtype (Anc_Subt)
3409 and then Is_OK_Static_Expression (Type_Low_Bound (Typ))
3410 and then Is_OK_Static_Expression (Type_High_Bound (Typ));
3413 -- Types other than string and scalar types are never static
3418 end Is_OK_Static_Subtype;
3420 ---------------------
3421 -- Is_Out_Of_Range --
3422 ---------------------
3424 function Is_Out_Of_Range
3427 Fixed_Int : Boolean := False;
3428 Int_Real : Boolean := False) return Boolean
3434 -- Universal types have no range limits, so always in range
3436 if Typ = Universal_Integer or else Typ = Universal_Real then
3439 -- Never out of range if not scalar type. Don't know if this can
3440 -- actually happen, but our spec allows it, so we must check!
3442 elsif not Is_Scalar_Type (Typ) then
3445 -- Never out of range if this is a generic type, since the bounds
3446 -- of generic types are junk. Note that if we only checked for
3447 -- static expressions (instead of compile time known values) below,
3448 -- we would not need this check, because values of a generic type
3449 -- can never be static, but they can be known at compile time.
3451 elsif Is_Generic_Type (Typ) then
3454 -- Never out of range unless we have a compile time known value
3456 elsif not Compile_Time_Known_Value (N) then
3461 Lo : constant Node_Id := Type_Low_Bound (Typ);
3462 Hi : constant Node_Id := Type_High_Bound (Typ);
3463 LB_Known : constant Boolean := Compile_Time_Known_Value (Lo);
3464 UB_Known : constant Boolean := Compile_Time_Known_Value (Hi);
3467 -- Real types (note that fixed-point types are not treated
3468 -- as being of a real type if the flag Fixed_Int is set,
3469 -- since in that case they are regarded as integer types).
3471 if Is_Floating_Point_Type (Typ)
3472 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
3475 Valr := Expr_Value_R (N);
3477 if LB_Known and then Valr < Expr_Value_R (Lo) then
3480 elsif UB_Known and then Expr_Value_R (Hi) < Valr then
3488 Val := Expr_Value (N);
3490 if LB_Known and then Val < Expr_Value (Lo) then
3493 elsif UB_Known and then Expr_Value (Hi) < Val then
3502 end Is_Out_Of_Range;
3504 ---------------------
3505 -- Is_Static_Range --
3506 ---------------------
3508 -- A static range is a range whose bounds are static expressions, or a
3509 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
3510 -- We have already converted range attribute references, so we get the
3511 -- "or" part of this rule without needing a special test.
3513 function Is_Static_Range (N : Node_Id) return Boolean is
3515 return Is_Static_Expression (Low_Bound (N))
3516 and then Is_Static_Expression (High_Bound (N));
3517 end Is_Static_Range;
3519 -----------------------
3520 -- Is_Static_Subtype --
3521 -----------------------
3523 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
3525 function Is_Static_Subtype (Typ : Entity_Id) return Boolean is
3526 Base_T : constant Entity_Id := Base_Type (Typ);
3527 Anc_Subt : Entity_Id;
3530 -- First a quick check on the non static subtype flag. As described
3531 -- in further detail in Einfo, this flag is not decisive in all cases,
3532 -- but if it is set, then the subtype is definitely non-static.
3534 if Is_Non_Static_Subtype (Typ) then
3538 Anc_Subt := Ancestor_Subtype (Typ);
3540 if Anc_Subt = Empty then
3544 if Is_Generic_Type (Root_Type (Base_T))
3545 or else Is_Generic_Actual_Type (Base_T)
3551 elsif Is_String_Type (Typ) then
3553 Ekind (Typ) = E_String_Literal_Subtype
3555 (Is_Static_Subtype (Component_Type (Typ))
3556 and then Is_Static_Subtype (Etype (First_Index (Typ))));
3560 elsif Is_Scalar_Type (Typ) then
3561 if Base_T = Typ then
3565 return Is_Static_Subtype (Anc_Subt)
3566 and then Is_Static_Expression (Type_Low_Bound (Typ))
3567 and then Is_Static_Expression (Type_High_Bound (Typ));
3570 -- Types other than string and scalar types are never static
3575 end Is_Static_Subtype;
3577 --------------------
3578 -- Not_Null_Range --
3579 --------------------
3581 function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
3582 Typ : constant Entity_Id := Etype (Lo);
3585 if not Compile_Time_Known_Value (Lo)
3586 or else not Compile_Time_Known_Value (Hi)
3591 if Is_Discrete_Type (Typ) then
3592 return Expr_Value (Lo) <= Expr_Value (Hi);
3595 pragma Assert (Is_Real_Type (Typ));
3597 return Expr_Value_R (Lo) <= Expr_Value_R (Hi);
3605 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean is
3607 -- We allow a maximum of 500,000 bits which seems a reasonable limit
3609 if Bits < 500_000 then
3613 Error_Msg_N ("static value too large, capacity exceeded", N);
3622 procedure Out_Of_Range (N : Node_Id) is
3624 -- If we have the static expression case, then this is an illegality
3625 -- in Ada 95 mode, except that in an instance, we never generate an
3626 -- error (if the error is legitimate, it was already diagnosed in
3627 -- the template). The expression to compute the length of a packed
3628 -- array is attached to the array type itself, and deserves a separate
3631 if Is_Static_Expression (N)
3632 and then not In_Instance
3633 and then not In_Inlined_Body
3634 and then Ada_Version >= Ada_95
3636 if Nkind (Parent (N)) = N_Defining_Identifier
3637 and then Is_Array_Type (Parent (N))
3638 and then Present (Packed_Array_Type (Parent (N)))
3639 and then Present (First_Rep_Item (Parent (N)))
3642 ("length of packed array must not exceed Integer''Last",
3643 First_Rep_Item (Parent (N)));
3644 Rewrite (N, Make_Integer_Literal (Sloc (N), Uint_1));
3647 Apply_Compile_Time_Constraint_Error
3648 (N, "value not in range of}", CE_Range_Check_Failed);
3651 -- Here we generate a warning for the Ada 83 case, or when we are
3652 -- in an instance, or when we have a non-static expression case.
3655 Apply_Compile_Time_Constraint_Error
3656 (N, "value not in range of}?", CE_Range_Check_Failed);
3660 -------------------------
3661 -- Rewrite_In_Raise_CE --
3662 -------------------------
3664 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id) is
3665 Typ : constant Entity_Id := Etype (N);
3668 -- If we want to raise CE in the condition of a raise_CE node
3669 -- we may as well get rid of the condition
3671 if Present (Parent (N))
3672 and then Nkind (Parent (N)) = N_Raise_Constraint_Error
3674 Set_Condition (Parent (N), Empty);
3676 -- If the expression raising CE is a N_Raise_CE node, we can use
3677 -- that one. We just preserve the type of the context
3679 elsif Nkind (Exp) = N_Raise_Constraint_Error then
3683 -- We have to build an explicit raise_ce node
3687 Make_Raise_Constraint_Error (Sloc (Exp),
3688 Reason => CE_Range_Check_Failed));
3689 Set_Raises_Constraint_Error (N);
3692 end Rewrite_In_Raise_CE;
3694 ---------------------
3695 -- String_Type_Len --
3696 ---------------------
3698 function String_Type_Len (Stype : Entity_Id) return Uint is
3699 NT : constant Entity_Id := Etype (First_Index (Stype));
3703 if Is_OK_Static_Subtype (NT) then
3706 T := Base_Type (NT);
3709 return Expr_Value (Type_High_Bound (T)) -
3710 Expr_Value (Type_Low_Bound (T)) + 1;
3711 end String_Type_Len;
3713 ------------------------------------
3714 -- Subtypes_Statically_Compatible --
3715 ------------------------------------
3717 function Subtypes_Statically_Compatible
3719 T2 : Entity_Id) return Boolean
3722 if Is_Scalar_Type (T1) then
3724 -- Definitely compatible if we match
3726 if Subtypes_Statically_Match (T1, T2) then
3729 -- If either subtype is nonstatic then they're not compatible
3731 elsif not Is_Static_Subtype (T1)
3732 or else not Is_Static_Subtype (T2)
3736 -- If either type has constraint error bounds, then consider that
3737 -- they match to avoid junk cascaded errors here.
3739 elsif not Is_OK_Static_Subtype (T1)
3740 or else not Is_OK_Static_Subtype (T2)
3744 -- Base types must match, but we don't check that (should
3745 -- we???) but we do at least check that both types are
3746 -- real, or both types are not real.
3748 elsif Is_Real_Type (T1) /= Is_Real_Type (T2) then
3751 -- Here we check the bounds
3755 LB1 : constant Node_Id := Type_Low_Bound (T1);
3756 HB1 : constant Node_Id := Type_High_Bound (T1);
3757 LB2 : constant Node_Id := Type_Low_Bound (T2);
3758 HB2 : constant Node_Id := Type_High_Bound (T2);
3761 if Is_Real_Type (T1) then
3763 (Expr_Value_R (LB1) > Expr_Value_R (HB1))
3765 (Expr_Value_R (LB2) <= Expr_Value_R (LB1)
3767 Expr_Value_R (HB1) <= Expr_Value_R (HB2));
3771 (Expr_Value (LB1) > Expr_Value (HB1))
3773 (Expr_Value (LB2) <= Expr_Value (LB1)
3775 Expr_Value (HB1) <= Expr_Value (HB2));
3780 elsif Is_Access_Type (T1) then
3781 return not Is_Constrained (T2)
3782 or else Subtypes_Statically_Match
3783 (Designated_Type (T1), Designated_Type (T2));
3786 return (Is_Composite_Type (T1) and then not Is_Constrained (T2))
3787 or else Subtypes_Statically_Match (T1, T2);
3789 end Subtypes_Statically_Compatible;
3791 -------------------------------
3792 -- Subtypes_Statically_Match --
3793 -------------------------------
3795 -- Subtypes statically match if they have statically matching constraints
3796 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
3797 -- they are the same identical constraint, or if they are static and the
3798 -- values match (RM 4.9.1(1)).
3800 function Subtypes_Statically_Match (T1, T2 : Entity_Id) return Boolean is
3802 -- A type always statically matches itself
3809 elsif Is_Scalar_Type (T1) then
3811 -- Base types must be the same
3813 if Base_Type (T1) /= Base_Type (T2) then
3817 -- A constrained numeric subtype never matches an unconstrained
3818 -- subtype, i.e. both types must be constrained or unconstrained.
3820 -- To understand the requirement for this test, see RM 4.9.1(1).
3821 -- As is made clear in RM 3.5.4(11), type Integer, for example
3822 -- is a constrained subtype with constraint bounds matching the
3823 -- bounds of its corresponding uncontrained base type. In this
3824 -- situation, Integer and Integer'Base do not statically match,
3825 -- even though they have the same bounds.
3827 -- We only apply this test to types in Standard and types that
3828 -- appear in user programs. That way, we do not have to be
3829 -- too careful about setting Is_Constrained right for itypes.
3831 if Is_Numeric_Type (T1)
3832 and then (Is_Constrained (T1) /= Is_Constrained (T2))
3833 and then (Scope (T1) = Standard_Standard
3834 or else Comes_From_Source (T1))
3835 and then (Scope (T2) = Standard_Standard
3836 or else Comes_From_Source (T2))
3840 -- A generic scalar type does not statically match its base
3841 -- type (AI-311). In this case we make sure that the formals,
3842 -- which are first subtypes of their bases, are constrained.
3844 elsif Is_Generic_Type (T1)
3845 and then Is_Generic_Type (T2)
3846 and then (Is_Constrained (T1) /= Is_Constrained (T2))
3851 -- If there was an error in either range, then just assume
3852 -- the types statically match to avoid further junk errors
3854 if Error_Posted (Scalar_Range (T1))
3856 Error_Posted (Scalar_Range (T2))
3861 -- Otherwise both types have bound that can be compared
3864 LB1 : constant Node_Id := Type_Low_Bound (T1);
3865 HB1 : constant Node_Id := Type_High_Bound (T1);
3866 LB2 : constant Node_Id := Type_Low_Bound (T2);
3867 HB2 : constant Node_Id := Type_High_Bound (T2);
3870 -- If the bounds are the same tree node, then match
3872 if LB1 = LB2 and then HB1 = HB2 then
3875 -- Otherwise bounds must be static and identical value
3878 if not Is_Static_Subtype (T1)
3879 or else not Is_Static_Subtype (T2)
3883 -- If either type has constraint error bounds, then say
3884 -- that they match to avoid junk cascaded errors here.
3886 elsif not Is_OK_Static_Subtype (T1)
3887 or else not Is_OK_Static_Subtype (T2)
3891 elsif Is_Real_Type (T1) then
3893 (Expr_Value_R (LB1) = Expr_Value_R (LB2))
3895 (Expr_Value_R (HB1) = Expr_Value_R (HB2));
3899 Expr_Value (LB1) = Expr_Value (LB2)
3901 Expr_Value (HB1) = Expr_Value (HB2);
3906 -- Type with discriminants
3908 elsif Has_Discriminants (T1) or else Has_Discriminants (T2) then
3909 if Has_Discriminants (T1) /= Has_Discriminants (T2) then
3914 DL1 : constant Elist_Id := Discriminant_Constraint (T1);
3915 DL2 : constant Elist_Id := Discriminant_Constraint (T2);
3917 DA1 : Elmt_Id := First_Elmt (DL1);
3918 DA2 : Elmt_Id := First_Elmt (DL2);
3924 elsif Is_Constrained (T1) /= Is_Constrained (T2) then
3928 while Present (DA1) loop
3930 Expr1 : constant Node_Id := Node (DA1);
3931 Expr2 : constant Node_Id := Node (DA2);
3934 if not Is_Static_Expression (Expr1)
3935 or else not Is_Static_Expression (Expr2)
3939 -- If either expression raised a constraint error,
3940 -- consider the expressions as matching, since this
3941 -- helps to prevent cascading errors.
3943 elsif Raises_Constraint_Error (Expr1)
3944 or else Raises_Constraint_Error (Expr2)
3948 elsif Expr_Value (Expr1) /= Expr_Value (Expr2) then
3960 -- A definite type does not match an indefinite or classwide type
3963 Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
3969 elsif Is_Array_Type (T1) then
3971 -- If either subtype is unconstrained then both must be,
3972 -- and if both are unconstrained then no further checking
3975 if not Is_Constrained (T1) or else not Is_Constrained (T2) then
3976 return not (Is_Constrained (T1) or else Is_Constrained (T2));
3979 -- Both subtypes are constrained, so check that the index
3980 -- subtypes statically match.
3983 Index1 : Node_Id := First_Index (T1);
3984 Index2 : Node_Id := First_Index (T2);
3987 while Present (Index1) loop
3989 Subtypes_Statically_Match (Etype (Index1), Etype (Index2))
3994 Next_Index (Index1);
3995 Next_Index (Index2);
4001 elsif Is_Access_Type (T1) then
4002 return Subtypes_Statically_Match
4003 (Designated_Type (T1),
4004 Designated_Type (T2));
4006 -- All other types definitely match
4011 end Subtypes_Statically_Match;
4017 function Test (Cond : Boolean) return Uint is
4026 ---------------------------------
4027 -- Test_Expression_Is_Foldable --
4028 ---------------------------------
4032 procedure Test_Expression_Is_Foldable
4041 -- If operand is Any_Type, just propagate to result and do not
4042 -- try to fold, this prevents cascaded errors.
4044 if Etype (Op1) = Any_Type then
4045 Set_Etype (N, Any_Type);
4049 -- If operand raises constraint error, then replace node N with the
4050 -- raise constraint error node, and we are obviously not foldable.
4051 -- Note that this replacement inherits the Is_Static_Expression flag
4052 -- from the operand.
4054 elsif Raises_Constraint_Error (Op1) then
4055 Rewrite_In_Raise_CE (N, Op1);
4059 -- If the operand is not static, then the result is not static, and
4060 -- all we have to do is to check the operand since it is now known
4061 -- to appear in a non-static context.
4063 elsif not Is_Static_Expression (Op1) then
4064 Check_Non_Static_Context (Op1);
4065 Fold := Compile_Time_Known_Value (Op1);
4068 -- An expression of a formal modular type is not foldable because
4069 -- the modulus is unknown.
4071 elsif Is_Modular_Integer_Type (Etype (Op1))
4072 and then Is_Generic_Type (Etype (Op1))
4074 Check_Non_Static_Context (Op1);
4078 -- Here we have the case of an operand whose type is OK, which is
4079 -- static, and which does not raise constraint error, we can fold.
4082 Set_Is_Static_Expression (N);
4086 end Test_Expression_Is_Foldable;
4090 procedure Test_Expression_Is_Foldable
4097 Rstat : constant Boolean := Is_Static_Expression (Op1)
4098 and then Is_Static_Expression (Op2);
4103 -- If either operand is Any_Type, just propagate to result and
4104 -- do not try to fold, this prevents cascaded errors.
4106 if Etype (Op1) = Any_Type or else Etype (Op2) = Any_Type then
4107 Set_Etype (N, Any_Type);
4111 -- If left operand raises constraint error, then replace node N with
4112 -- the raise constraint error node, and we are obviously not foldable.
4113 -- Is_Static_Expression is set from the two operands in the normal way,
4114 -- and we check the right operand if it is in a non-static context.
4116 elsif Raises_Constraint_Error (Op1) then
4118 Check_Non_Static_Context (Op2);
4121 Rewrite_In_Raise_CE (N, Op1);
4122 Set_Is_Static_Expression (N, Rstat);
4126 -- Similar processing for the case of the right operand. Note that
4127 -- we don't use this routine for the short-circuit case, so we do
4128 -- not have to worry about that special case here.
4130 elsif Raises_Constraint_Error (Op2) then
4132 Check_Non_Static_Context (Op1);
4135 Rewrite_In_Raise_CE (N, Op2);
4136 Set_Is_Static_Expression (N, Rstat);
4140 -- Exclude expressions of a generic modular type, as above
4142 elsif Is_Modular_Integer_Type (Etype (Op1))
4143 and then Is_Generic_Type (Etype (Op1))
4145 Check_Non_Static_Context (Op1);
4149 -- If result is not static, then check non-static contexts on operands
4150 -- since one of them may be static and the other one may not be static
4152 elsif not Rstat then
4153 Check_Non_Static_Context (Op1);
4154 Check_Non_Static_Context (Op2);
4155 Fold := Compile_Time_Known_Value (Op1)
4156 and then Compile_Time_Known_Value (Op2);
4159 -- Else result is static and foldable. Both operands are static,
4160 -- and neither raises constraint error, so we can definitely fold.
4163 Set_Is_Static_Expression (N);
4168 end Test_Expression_Is_Foldable;
4174 procedure To_Bits (U : Uint; B : out Bits) is
4176 for J in 0 .. B'Last loop
4177 B (J) := (U / (2 ** J)) mod 2 /= 0;
4181 --------------------
4182 -- Why_Not_Static --
4183 --------------------
4185 procedure Why_Not_Static (Expr : Node_Id) is
4186 N : constant Node_Id := Original_Node (Expr);
4190 procedure Why_Not_Static_List (L : List_Id);
4191 -- A version that can be called on a list of expressions. Finds
4192 -- all non-static violations in any element of the list.
4194 -------------------------
4195 -- Why_Not_Static_List --
4196 -------------------------
4198 procedure Why_Not_Static_List (L : List_Id) is
4202 if Is_Non_Empty_List (L) then
4204 while Present (N) loop
4209 end Why_Not_Static_List;
4211 -- Start of processing for Why_Not_Static
4214 -- If in ACATS mode (debug flag 2), then suppress all these
4215 -- messages, this avoids massive updates to the ACATS base line.
4217 if Debug_Flag_2 then
4221 -- Ignore call on error or empty node
4223 if No (Expr) or else Nkind (Expr) = N_Error then
4227 -- Preprocessing for sub expressions
4229 if Nkind (Expr) in N_Subexpr then
4231 -- Nothing to do if expression is static
4233 if Is_OK_Static_Expression (Expr) then
4237 -- Test for constraint error raised
4239 if Raises_Constraint_Error (Expr) then
4241 ("expression raises exception, cannot be static " &
4242 "('R'M 4.9(34))!", N);
4246 -- If no type, then something is pretty wrong, so ignore
4248 Typ := Etype (Expr);
4254 -- Type must be scalar or string type
4256 if not Is_Scalar_Type (Typ)
4257 and then not Is_String_Type (Typ)
4260 ("static expression must have scalar or string type " &
4261 "('R'M 4.9(2))!", N);
4266 -- If we got through those checks, test particular node kind
4269 when N_Expanded_Name | N_Identifier | N_Operator_Symbol =>
4272 if Is_Named_Number (E) then
4275 elsif Ekind (E) = E_Constant then
4276 if not Is_Static_Expression (Constant_Value (E)) then
4278 ("& is not a static constant ('R'M 4.9(5))!", N, E);
4283 ("& is not static constant or named number " &
4284 "('R'M 4.9(5))!", N, E);
4287 when N_Binary_Op | N_And_Then | N_Or_Else | N_In | N_Not_In =>
4288 if Nkind (N) in N_Op_Shift then
4290 ("shift functions are never static ('R'M 4.9(6,18))!", N);
4293 Why_Not_Static (Left_Opnd (N));
4294 Why_Not_Static (Right_Opnd (N));
4298 Why_Not_Static (Right_Opnd (N));
4300 when N_Attribute_Reference =>
4301 Why_Not_Static_List (Expressions (N));
4303 E := Etype (Prefix (N));
4305 if E = Standard_Void_Type then
4309 -- Special case non-scalar'Size since this is a common error
4311 if Attribute_Name (N) = Name_Size then
4313 ("size attribute is only static for scalar type " &
4314 "('R'M 4.9(7,8))", N);
4318 elsif Is_Array_Type (E) then
4319 if Attribute_Name (N) /= Name_First
4321 Attribute_Name (N) /= Name_Last
4323 Attribute_Name (N) /= Name_Length
4326 ("static array attribute must be Length, First, or Last " &
4327 "('R'M 4.9(8))!", N);
4329 -- Since we know the expression is not-static (we already
4330 -- tested for this, must mean array is not static).
4334 ("prefix is non-static array ('R'M 4.9(8))!", Prefix (N));
4339 -- Special case generic types, since again this is a common
4340 -- source of confusion.
4342 elsif Is_Generic_Actual_Type (E)
4347 ("attribute of generic type is never static " &
4348 "('R'M 4.9(7,8))!", N);
4350 elsif Is_Static_Subtype (E) then
4353 elsif Is_Scalar_Type (E) then
4355 ("prefix type for attribute is not static scalar subtype " &
4356 "('R'M 4.9(7))!", N);
4360 ("static attribute must apply to array/scalar type " &
4361 "('R'M 4.9(7,8))!", N);
4364 when N_String_Literal =>
4366 ("subtype of string literal is non-static ('R'M 4.9(4))!", N);
4368 when N_Explicit_Dereference =>
4370 ("explicit dereference is never static ('R'M 4.9)!", N);
4372 when N_Function_Call =>
4373 Why_Not_Static_List (Parameter_Associations (N));
4374 Error_Msg_N ("non-static function call ('R'M 4.9(6,18))!", N);
4376 when N_Parameter_Association =>
4377 Why_Not_Static (Explicit_Actual_Parameter (N));
4379 when N_Indexed_Component =>
4381 ("indexed component is never static ('R'M 4.9)!", N);
4383 when N_Procedure_Call_Statement =>
4385 ("procedure call is never static ('R'M 4.9)!", N);
4387 when N_Qualified_Expression =>
4388 Why_Not_Static (Expression (N));
4390 when N_Aggregate | N_Extension_Aggregate =>
4392 ("an aggregate is never static ('R'M 4.9)!", N);
4395 Why_Not_Static (Low_Bound (N));
4396 Why_Not_Static (High_Bound (N));
4398 when N_Range_Constraint =>
4399 Why_Not_Static (Range_Expression (N));
4401 when N_Subtype_Indication =>
4402 Why_Not_Static (Constraint (N));
4404 when N_Selected_Component =>
4406 ("selected component is never static ('R'M 4.9)!", N);
4410 ("slice is never static ('R'M 4.9)!", N);
4412 when N_Type_Conversion =>
4413 Why_Not_Static (Expression (N));
4415 if not Is_Scalar_Type (Etype (Prefix (N)))
4416 or else not Is_Static_Subtype (Etype (Prefix (N)))
4419 ("static conversion requires static scalar subtype result " &
4420 "('R'M 4.9(9))!", N);
4423 when N_Unchecked_Type_Conversion =>
4425 ("unchecked type conversion is never static ('R'M 4.9)!", N);