1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2011, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Checks; use Checks;
28 with Debug; use Debug;
29 with Einfo; use Einfo;
30 with Elists; use Elists;
31 with Errout; use Errout;
32 with Eval_Fat; use Eval_Fat;
33 with Exp_Util; use Exp_Util;
34 with Freeze; use Freeze;
36 with Namet; use Namet;
37 with Nmake; use Nmake;
38 with Nlists; use Nlists;
41 with Sem_Aux; use Sem_Aux;
42 with Sem_Cat; use Sem_Cat;
43 with Sem_Ch6; use Sem_Ch6;
44 with Sem_Ch8; use Sem_Ch8;
45 with Sem_Res; use Sem_Res;
46 with Sem_Util; use Sem_Util;
47 with Sem_Type; use Sem_Type;
48 with Sem_Warn; use Sem_Warn;
49 with Sinfo; use Sinfo;
50 with Snames; use Snames;
51 with Stand; use Stand;
52 with Stringt; use Stringt;
53 with Tbuild; use Tbuild;
55 package body Sem_Eval is
57 -----------------------------------------
58 -- Handling of Compile Time Evaluation --
59 -----------------------------------------
61 -- The compile time evaluation of expressions is distributed over several
62 -- Eval_xxx procedures. These procedures are called immediately after
63 -- a subexpression is resolved and is therefore accomplished in a bottom
64 -- up fashion. The flags are synthesized using the following approach.
66 -- Is_Static_Expression is determined by following the detailed rules
67 -- in RM 4.9(4-14). This involves testing the Is_Static_Expression
68 -- flag of the operands in many cases.
70 -- Raises_Constraint_Error is set if any of the operands have the flag
71 -- set or if an attempt to compute the value of the current expression
72 -- results in detection of a runtime constraint error.
74 -- As described in the spec, the requirement is that Is_Static_Expression
75 -- be accurately set, and in addition for nodes for which this flag is set,
76 -- Raises_Constraint_Error must also be set. Furthermore a node which has
77 -- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
78 -- requirement is that the expression value must be precomputed, and the
79 -- node is either a literal, or the name of a constant entity whose value
80 -- is a static expression.
82 -- The general approach is as follows. First compute Is_Static_Expression.
83 -- If the node is not static, then the flag is left off in the node and
84 -- we are all done. Otherwise for a static node, we test if any of the
85 -- operands will raise constraint error, and if so, propagate the flag
86 -- Raises_Constraint_Error to the result node and we are done (since the
87 -- error was already posted at a lower level).
89 -- For the case of a static node whose operands do not raise constraint
90 -- error, we attempt to evaluate the node. If this evaluation succeeds,
91 -- then the node is replaced by the result of this computation. If the
92 -- evaluation raises constraint error, then we rewrite the node with
93 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
94 -- to post appropriate error messages.
100 type Bits is array (Nat range <>) of Boolean;
101 -- Used to convert unsigned (modular) values for folding logical ops
103 -- The following definitions are used to maintain a cache of nodes that
104 -- have compile time known values. The cache is maintained only for
105 -- discrete types (the most common case), and is populated by calls to
106 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
107 -- since it is possible for the status to change (in particular it is
108 -- possible for a node to get replaced by a constraint error node).
110 CV_Bits : constant := 5;
111 -- Number of low order bits of Node_Id value used to reference entries
112 -- in the cache table.
114 CV_Cache_Size : constant Nat := 2 ** CV_Bits;
115 -- Size of cache for compile time values
117 subtype CV_Range is Nat range 0 .. CV_Cache_Size;
119 type CV_Entry is record
124 type CV_Cache_Array is array (CV_Range) of CV_Entry;
126 CV_Cache : CV_Cache_Array := (others => (Node_High_Bound, Uint_0));
127 -- This is the actual cache, with entries consisting of node/value pairs,
128 -- and the impossible value Node_High_Bound used for unset entries.
130 type Range_Membership is (In_Range, Out_Of_Range, Unknown);
131 -- Range membership may either be statically known to be in range or out
132 -- of range, or not statically known. Used for Test_In_Range below.
134 -----------------------
135 -- Local Subprograms --
136 -----------------------
138 function From_Bits (B : Bits; T : Entity_Id) return Uint;
139 -- Converts a bit string of length B'Length to a Uint value to be used
140 -- for a target of type T, which is a modular type. This procedure
141 -- includes the necessary reduction by the modulus in the case of a
142 -- non-binary modulus (for a binary modulus, the bit string is the
143 -- right length any way so all is well).
145 function Get_String_Val (N : Node_Id) return Node_Id;
146 -- Given a tree node for a folded string or character value, returns
147 -- the corresponding string literal or character literal (one of the
148 -- two must be available, or the operand would not have been marked
149 -- as foldable in the earlier analysis of the operation).
151 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean;
152 -- Bits represents the number of bits in an integer value to be computed
153 -- (but the value has not been computed yet). If this value in Bits is
154 -- reasonable, a result of True is returned, with the implication that
155 -- the caller should go ahead and complete the calculation. If the value
156 -- in Bits is unreasonably large, then an error is posted on node N, and
157 -- False is returned (and the caller skips the proposed calculation).
159 procedure Out_Of_Range (N : Node_Id);
160 -- This procedure is called if it is determined that node N, which
161 -- appears in a non-static context, is a compile time known value
162 -- which is outside its range, i.e. the range of Etype. This is used
163 -- in contexts where this is an illegality if N is static, and should
164 -- generate a warning otherwise.
166 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id);
167 -- N and Exp are nodes representing an expression, Exp is known
168 -- to raise CE. N is rewritten in term of Exp in the optimal way.
170 function String_Type_Len (Stype : Entity_Id) return Uint;
171 -- Given a string type, determines the length of the index type, or,
172 -- if this index type is non-static, the length of the base type of
173 -- this index type. Note that if the string type is itself static,
174 -- then the index type is static, so the second case applies only
175 -- if the string type passed is non-static.
177 function Test (Cond : Boolean) return Uint;
178 pragma Inline (Test);
179 -- This function simply returns the appropriate Boolean'Pos value
180 -- corresponding to the value of Cond as a universal integer. It is
181 -- used for producing the result of the static evaluation of the
184 function Find_Universal_Operator_Type (N : Node_Id) return Entity_Id;
185 -- Check whether an arithmetic operation with universal operands which
186 -- is a rewritten function call with an explicit scope indication is
187 -- ambiguous: P."+" (1, 2) will be ambiguous if there is more than one
188 -- visible numeric type declared in P and the context does not impose a
189 -- type on the result (e.g. in the expression of a type conversion).
190 -- If ambiguous, emit an error and return Empty, else return the result
191 -- type of the operator.
193 procedure Test_Expression_Is_Foldable
198 -- Tests to see if expression N whose single operand is Op1 is foldable,
199 -- i.e. the operand value is known at compile time. If the operation is
200 -- foldable, then Fold is True on return, and Stat indicates whether
201 -- the result is static (i.e. both operands were static). Note that it
202 -- is quite possible for Fold to be True, and Stat to be False, since
203 -- there are cases in which we know the value of an operand even though
204 -- it is not technically static (e.g. the static lower bound of a range
205 -- whose upper bound is non-static).
207 -- If Stat is set False on return, then Test_Expression_Is_Foldable makes a
208 -- call to Check_Non_Static_Context on the operand. If Fold is False on
209 -- return, then all processing is complete, and the caller should
210 -- return, since there is nothing else to do.
212 -- If Stat is set True on return, then Is_Static_Expression is also set
213 -- true in node N. There are some cases where this is over-enthusiastic,
214 -- e.g. in the two operand case below, for string comparison, the result
215 -- is not static even though the two operands are static. In such cases,
216 -- the caller must reset the Is_Static_Expression flag in N.
218 procedure Test_Expression_Is_Foldable
224 -- Same processing, except applies to an expression N with two operands
227 function Test_In_Range
230 Assume_Valid : Boolean;
232 Int_Real : Boolean) return Range_Membership;
233 -- Common processing for Is_In_Range and Is_Out_Of_Range:
234 -- Returns In_Range or Out_Of_Range if it can be guaranteed at compile time
235 -- that expression N is known to be in or out of range of the subtype Typ.
236 -- If not compile time known, Unknown is returned.
237 -- See documentation of Is_In_Range for complete description of parameters.
239 procedure To_Bits (U : Uint; B : out Bits);
240 -- Converts a Uint value to a bit string of length B'Length
242 ------------------------------
243 -- Check_Non_Static_Context --
244 ------------------------------
246 procedure Check_Non_Static_Context (N : Node_Id) is
247 T : constant Entity_Id := Etype (N);
248 Checks_On : constant Boolean :=
249 not Index_Checks_Suppressed (T)
250 and not Range_Checks_Suppressed (T);
253 -- Ignore cases of non-scalar types or error types
255 if T = Any_Type or else not Is_Scalar_Type (T) then
259 -- At this stage we have a scalar type. If we have an expression
260 -- that raises CE, then we already issued a warning or error msg
261 -- so there is nothing more to be done in this routine.
263 if Raises_Constraint_Error (N) then
267 -- Now we have a scalar type which is not marked as raising a
268 -- constraint error exception. The main purpose of this routine
269 -- is to deal with static expressions appearing in a non-static
270 -- context. That means that if we do not have a static expression
271 -- then there is not much to do. The one case that we deal with
272 -- here is that if we have a floating-point value that is out of
273 -- range, then we post a warning that an infinity will result.
275 if not Is_Static_Expression (N) then
276 if Is_Floating_Point_Type (T)
277 and then Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True)
280 ("?float value out of range, infinity will be generated", N);
286 -- Here we have the case of outer level static expression of
287 -- scalar type, where the processing of this procedure is needed.
289 -- For real types, this is where we convert the value to a machine
290 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should
291 -- only need to do this if the parent is a constant declaration,
292 -- since in other cases, gigi should do the necessary conversion
293 -- correctly, but experimentation shows that this is not the case
294 -- on all machines, in particular if we do not convert all literals
295 -- to machine values in non-static contexts, then ACVC test C490001
296 -- fails on Sparc/Solaris and SGI/Irix.
298 if Nkind (N) = N_Real_Literal
299 and then not Is_Machine_Number (N)
300 and then not Is_Generic_Type (Etype (N))
301 and then Etype (N) /= Universal_Real
303 -- Check that value is in bounds before converting to machine
304 -- number, so as not to lose case where value overflows in the
305 -- least significant bit or less. See B490001.
307 if Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True) then
312 -- Note: we have to copy the node, to avoid problems with conformance
313 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
315 Rewrite (N, New_Copy (N));
317 if not Is_Floating_Point_Type (T) then
319 (N, Corresponding_Integer_Value (N) * Small_Value (T));
321 elsif not UR_Is_Zero (Realval (N)) then
323 -- Note: even though RM 4.9(38) specifies biased rounding,
324 -- this has been modified by AI-100 in order to prevent
325 -- confusing differences in rounding between static and
326 -- non-static expressions. AI-100 specifies that the effect
327 -- of such rounding is implementation dependent, and in GNAT
328 -- we round to nearest even to match the run-time behavior.
331 (N, Machine (Base_Type (T), Realval (N), Round_Even, N));
334 Set_Is_Machine_Number (N);
337 -- Check for out of range universal integer. This is a non-static
338 -- context, so the integer value must be in range of the runtime
339 -- representation of universal integers.
341 -- We do this only within an expression, because that is the only
342 -- case in which non-static universal integer values can occur, and
343 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
344 -- called in contexts like the expression of a number declaration where
345 -- we certainly want to allow out of range values.
347 if Etype (N) = Universal_Integer
348 and then Nkind (N) = N_Integer_Literal
349 and then Nkind (Parent (N)) in N_Subexpr
351 (Intval (N) < Expr_Value (Type_Low_Bound (Universal_Integer))
353 Intval (N) > Expr_Value (Type_High_Bound (Universal_Integer)))
355 Apply_Compile_Time_Constraint_Error
356 (N, "non-static universal integer value out of range?",
357 CE_Range_Check_Failed);
359 -- Check out of range of base type
361 elsif Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True) then
364 -- Give warning if outside subtype (where one or both of the bounds of
365 -- the subtype is static). This warning is omitted if the expression
366 -- appears in a range that could be null (warnings are handled elsewhere
369 elsif T /= Base_Type (T)
370 and then Nkind (Parent (N)) /= N_Range
372 if Is_In_Range (N, T, Assume_Valid => True) then
375 elsif Is_Out_Of_Range (N, T, Assume_Valid => True) then
376 Apply_Compile_Time_Constraint_Error
377 (N, "value not in range of}?", CE_Range_Check_Failed);
380 Enable_Range_Check (N);
383 Set_Do_Range_Check (N, False);
386 end Check_Non_Static_Context;
388 ---------------------------------
389 -- Check_String_Literal_Length --
390 ---------------------------------
392 procedure Check_String_Literal_Length (N : Node_Id; Ttype : Entity_Id) is
394 if not Raises_Constraint_Error (N)
395 and then Is_Constrained (Ttype)
398 UI_From_Int (String_Length (Strval (N))) /= String_Type_Len (Ttype)
400 Apply_Compile_Time_Constraint_Error
401 (N, "string length wrong for}?",
402 CE_Length_Check_Failed,
407 end Check_String_Literal_Length;
409 --------------------------
410 -- Compile_Time_Compare --
411 --------------------------
413 function Compile_Time_Compare
415 Assume_Valid : Boolean) return Compare_Result
417 Discard : aliased Uint;
419 return Compile_Time_Compare (L, R, Discard'Access, Assume_Valid);
420 end Compile_Time_Compare;
422 function Compile_Time_Compare
425 Assume_Valid : Boolean;
426 Rec : Boolean := False) return Compare_Result
428 Ltyp : Entity_Id := Underlying_Type (Etype (L));
429 Rtyp : Entity_Id := Underlying_Type (Etype (R));
430 -- These get reset to the base type for the case of entities where
431 -- Is_Known_Valid is not set. This takes care of handling possible
432 -- invalid representations using the value of the base type, in
433 -- accordance with RM 13.9.1(10).
435 Discard : aliased Uint;
437 procedure Compare_Decompose
441 -- This procedure decomposes the node N into an expression node and a
442 -- signed offset, so that the value of N is equal to the value of R plus
443 -- the value V (which may be negative). If no such decomposition is
444 -- possible, then on return R is a copy of N, and V is set to zero.
446 function Compare_Fixup (N : Node_Id) return Node_Id;
447 -- This function deals with replacing 'Last and 'First references with
448 -- their corresponding type bounds, which we then can compare. The
449 -- argument is the original node, the result is the identity, unless we
450 -- have a 'Last/'First reference in which case the value returned is the
451 -- appropriate type bound.
453 function Is_Known_Valid_Operand (Opnd : Node_Id) return Boolean;
454 -- Even if the context does not assume that values are valid, some
455 -- simple cases can be recognized.
457 function Is_Same_Value (L, R : Node_Id) return Boolean;
458 -- Returns True iff L and R represent expressions that definitely
459 -- have identical (but not necessarily compile time known) values
460 -- Indeed the caller is expected to have already dealt with the
461 -- cases of compile time known values, so these are not tested here.
463 -----------------------
464 -- Compare_Decompose --
465 -----------------------
467 procedure Compare_Decompose
473 if Nkind (N) = N_Op_Add
474 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
477 V := Intval (Right_Opnd (N));
480 elsif Nkind (N) = N_Op_Subtract
481 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
484 V := UI_Negate (Intval (Right_Opnd (N)));
487 elsif Nkind (N) = N_Attribute_Reference then
488 if Attribute_Name (N) = Name_Succ then
489 R := First (Expressions (N));
493 elsif Attribute_Name (N) = Name_Pred then
494 R := First (Expressions (N));
502 end Compare_Decompose;
508 function Compare_Fixup (N : Node_Id) return Node_Id is
514 if Nkind (N) = N_Attribute_Reference
515 and then (Attribute_Name (N) = Name_First
517 Attribute_Name (N) = Name_Last)
519 Xtyp := Etype (Prefix (N));
521 -- If we have no type, then just abandon the attempt to do
522 -- a fixup, this is probably the result of some other error.
528 -- Dereference an access type
530 if Is_Access_Type (Xtyp) then
531 Xtyp := Designated_Type (Xtyp);
534 -- If we don't have an array type at this stage, something
535 -- is peculiar, e.g. another error, and we abandon the attempt
538 if not Is_Array_Type (Xtyp) then
542 -- Ignore unconstrained array, since bounds are not meaningful
544 if not Is_Constrained (Xtyp) then
548 if Ekind (Xtyp) = E_String_Literal_Subtype then
549 if Attribute_Name (N) = Name_First then
550 return String_Literal_Low_Bound (Xtyp);
552 else -- Attribute_Name (N) = Name_Last
553 return Make_Integer_Literal (Sloc (N),
554 Intval => Intval (String_Literal_Low_Bound (Xtyp))
555 + String_Literal_Length (Xtyp));
559 -- Find correct index type
561 Indx := First_Index (Xtyp);
563 if Present (Expressions (N)) then
564 Subs := UI_To_Int (Expr_Value (First (Expressions (N))));
566 for J in 2 .. Subs loop
567 Indx := Next_Index (Indx);
571 Xtyp := Etype (Indx);
573 if Attribute_Name (N) = Name_First then
574 return Type_Low_Bound (Xtyp);
576 else -- Attribute_Name (N) = Name_Last
577 return Type_High_Bound (Xtyp);
584 ----------------------------
585 -- Is_Known_Valid_Operand --
586 ----------------------------
588 function Is_Known_Valid_Operand (Opnd : Node_Id) return Boolean is
590 return (Is_Entity_Name (Opnd)
592 (Is_Known_Valid (Entity (Opnd))
593 or else Ekind (Entity (Opnd)) = E_In_Parameter
595 (Ekind (Entity (Opnd)) in Object_Kind
596 and then Present (Current_Value (Entity (Opnd))))))
597 or else Is_OK_Static_Expression (Opnd);
598 end Is_Known_Valid_Operand;
604 function Is_Same_Value (L, R : Node_Id) return Boolean is
605 Lf : constant Node_Id := Compare_Fixup (L);
606 Rf : constant Node_Id := Compare_Fixup (R);
608 function Is_Same_Subscript (L, R : List_Id) return Boolean;
609 -- L, R are the Expressions values from two attribute nodes for First
610 -- or Last attributes. Either may be set to No_List if no expressions
611 -- are present (indicating subscript 1). The result is True if both
612 -- expressions represent the same subscript (note one case is where
613 -- one subscript is missing and the other is explicitly set to 1).
615 -----------------------
616 -- Is_Same_Subscript --
617 -----------------------
619 function Is_Same_Subscript (L, R : List_Id) return Boolean is
625 return Expr_Value (First (R)) = Uint_1;
630 return Expr_Value (First (L)) = Uint_1;
632 return Expr_Value (First (L)) = Expr_Value (First (R));
635 end Is_Same_Subscript;
637 -- Start of processing for Is_Same_Value
640 -- Values are the same if they refer to the same entity and the
641 -- entity is non-volatile. This does not however apply to Float
642 -- types, since we may have two NaN values and they should never
645 -- If the entity is a discriminant, the two expressions may be bounds
646 -- of components of objects of the same discriminated type. The
647 -- values of the discriminants are not static, and therefore the
648 -- result is unknown.
650 -- It would be better to comment individual branches of this test ???
652 if Nkind_In (Lf, N_Identifier, N_Expanded_Name)
653 and then Nkind_In (Rf, N_Identifier, N_Expanded_Name)
654 and then Entity (Lf) = Entity (Rf)
655 and then Ekind (Entity (Lf)) /= E_Discriminant
656 and then Present (Entity (Lf))
657 and then not Is_Floating_Point_Type (Etype (L))
658 and then not Is_Volatile_Reference (L)
659 and then not Is_Volatile_Reference (R)
663 -- Or if they are compile time known and identical
665 elsif Compile_Time_Known_Value (Lf)
667 Compile_Time_Known_Value (Rf)
668 and then Expr_Value (Lf) = Expr_Value (Rf)
672 -- False if Nkind of the two nodes is different for remaining cases
674 elsif Nkind (Lf) /= Nkind (Rf) then
677 -- True if both 'First or 'Last values applying to the same entity
678 -- (first and last don't change even if value does). Note that we
679 -- need this even with the calls to Compare_Fixup, to handle the
680 -- case of unconstrained array attributes where Compare_Fixup
681 -- cannot find useful bounds.
683 elsif Nkind (Lf) = N_Attribute_Reference
684 and then Attribute_Name (Lf) = Attribute_Name (Rf)
685 and then (Attribute_Name (Lf) = Name_First
687 Attribute_Name (Lf) = Name_Last)
688 and then Nkind_In (Prefix (Lf), N_Identifier, N_Expanded_Name)
689 and then Nkind_In (Prefix (Rf), N_Identifier, N_Expanded_Name)
690 and then Entity (Prefix (Lf)) = Entity (Prefix (Rf))
691 and then Is_Same_Subscript (Expressions (Lf), Expressions (Rf))
695 -- True if the same selected component from the same record
697 elsif Nkind (Lf) = N_Selected_Component
698 and then Selector_Name (Lf) = Selector_Name (Rf)
699 and then Is_Same_Value (Prefix (Lf), Prefix (Rf))
703 -- True if the same unary operator applied to the same operand
705 elsif Nkind (Lf) in N_Unary_Op
706 and then Is_Same_Value (Right_Opnd (Lf), Right_Opnd (Rf))
710 -- True if the same binary operator applied to the same operands
712 elsif Nkind (Lf) in N_Binary_Op
713 and then Is_Same_Value (Left_Opnd (Lf), Left_Opnd (Rf))
714 and then Is_Same_Value (Right_Opnd (Lf), Right_Opnd (Rf))
718 -- All other cases, we can't tell, so return False
725 -- Start of processing for Compile_Time_Compare
730 -- If either operand could raise constraint error, then we cannot
731 -- know the result at compile time (since CE may be raised!)
733 if not (Cannot_Raise_Constraint_Error (L)
735 Cannot_Raise_Constraint_Error (R))
740 -- Identical operands are most certainly equal
745 -- If expressions have no types, then do not attempt to determine if
746 -- they are the same, since something funny is going on. One case in
747 -- which this happens is during generic template analysis, when bounds
748 -- are not fully analyzed.
750 elsif No (Ltyp) or else No (Rtyp) then
753 -- We do not attempt comparisons for packed arrays arrays represented as
754 -- modular types, where the semantics of comparison is quite different.
756 elsif Is_Packed_Array_Type (Ltyp)
757 and then Is_Modular_Integer_Type (Ltyp)
761 -- For access types, the only time we know the result at compile time
762 -- (apart from identical operands, which we handled already) is if we
763 -- know one operand is null and the other is not, or both operands are
766 elsif Is_Access_Type (Ltyp) then
767 if Known_Null (L) then
768 if Known_Null (R) then
770 elsif Known_Non_Null (R) then
776 elsif Known_Non_Null (L) and then Known_Null (R) then
783 -- Case where comparison involves two compile time known values
785 elsif Compile_Time_Known_Value (L)
786 and then Compile_Time_Known_Value (R)
788 -- For the floating-point case, we have to be a little careful, since
789 -- at compile time we are dealing with universal exact values, but at
790 -- runtime, these will be in non-exact target form. That's why the
791 -- returned results are LE and GE below instead of LT and GT.
793 if Is_Floating_Point_Type (Ltyp)
795 Is_Floating_Point_Type (Rtyp)
798 Lo : constant Ureal := Expr_Value_R (L);
799 Hi : constant Ureal := Expr_Value_R (R);
811 -- For string types, we have two string literals and we proceed to
812 -- compare them using the Ada style dictionary string comparison.
814 elsif not Is_Scalar_Type (Ltyp) then
816 Lstring : constant String_Id := Strval (Expr_Value_S (L));
817 Rstring : constant String_Id := Strval (Expr_Value_S (R));
818 Llen : constant Nat := String_Length (Lstring);
819 Rlen : constant Nat := String_Length (Rstring);
822 for J in 1 .. Nat'Min (Llen, Rlen) loop
824 LC : constant Char_Code := Get_String_Char (Lstring, J);
825 RC : constant Char_Code := Get_String_Char (Rstring, J);
837 elsif Llen > Rlen then
844 -- For remaining scalar cases we know exactly (note that this does
845 -- include the fixed-point case, where we know the run time integer
850 Lo : constant Uint := Expr_Value (L);
851 Hi : constant Uint := Expr_Value (R);
868 -- Cases where at least one operand is not known at compile time
871 -- Remaining checks apply only for discrete types
873 if not Is_Discrete_Type (Ltyp)
874 or else not Is_Discrete_Type (Rtyp)
879 -- Defend against generic types, or actually any expressions that
880 -- contain a reference to a generic type from within a generic
881 -- template. We don't want to do any range analysis of such
882 -- expressions for two reasons. First, the bounds of a generic type
883 -- itself are junk and cannot be used for any kind of analysis.
884 -- Second, we may have a case where the range at run time is indeed
885 -- known, but we don't want to do compile time analysis in the
886 -- template based on that range since in an instance the value may be
887 -- static, and able to be elaborated without reference to the bounds
888 -- of types involved. As an example, consider:
890 -- (F'Pos (F'Last) + 1) > Integer'Last
892 -- The expression on the left side of > is Universal_Integer and thus
893 -- acquires the type Integer for evaluation at run time, and at run
894 -- time it is true that this condition is always False, but within
895 -- an instance F may be a type with a static range greater than the
896 -- range of Integer, and the expression statically evaluates to True.
898 if References_Generic_Formal_Type (L)
900 References_Generic_Formal_Type (R)
905 -- Replace types by base types for the case of entities which are
906 -- not known to have valid representations. This takes care of
907 -- properly dealing with invalid representations.
909 if not Assume_Valid and then not Assume_No_Invalid_Values then
910 if Is_Entity_Name (L) and then not Is_Known_Valid (Entity (L)) then
911 Ltyp := Underlying_Type (Base_Type (Ltyp));
914 if Is_Entity_Name (R) and then not Is_Known_Valid (Entity (R)) then
915 Rtyp := Underlying_Type (Base_Type (Rtyp));
919 -- Try range analysis on variables and see if ranges are disjoint
927 Determine_Range (L, LOK, LLo, LHi, Assume_Valid);
928 Determine_Range (R, ROK, RLo, RHi, Assume_Valid);
942 -- If the range includes a single literal and we can assume
943 -- validity then the result is known even if an operand is
958 elsif not Is_Known_Valid_Operand (L)
959 and then not Assume_Valid
961 if Is_Same_Value (L, R) then
968 -- If the range of either operand cannot be determined, nothing
969 -- further can be inferred.
976 -- Here is where we check for comparisons against maximum bounds of
977 -- types, where we know that no value can be outside the bounds of
978 -- the subtype. Note that this routine is allowed to assume that all
979 -- expressions are within their subtype bounds. Callers wishing to
980 -- deal with possibly invalid values must in any case take special
981 -- steps (e.g. conversions to larger types) to avoid this kind of
982 -- optimization, which is always considered to be valid. We do not
983 -- attempt this optimization with generic types, since the type
984 -- bounds may not be meaningful in this case.
986 -- We are in danger of an infinite recursion here. It does not seem
987 -- useful to go more than one level deep, so the parameter Rec is
988 -- used to protect ourselves against this infinite recursion.
992 -- See if we can get a decisive check against one operand and
993 -- a bound of the other operand (four possible tests here).
994 -- Note that we avoid testing junk bounds of a generic type.
996 if not Is_Generic_Type (Rtyp) then
997 case Compile_Time_Compare (L, Type_Low_Bound (Rtyp),
999 Assume_Valid, Rec => True)
1001 when LT => return LT;
1002 when LE => return LE;
1003 when EQ => return LE;
1004 when others => null;
1007 case Compile_Time_Compare (L, Type_High_Bound (Rtyp),
1009 Assume_Valid, Rec => True)
1011 when GT => return GT;
1012 when GE => return GE;
1013 when EQ => return GE;
1014 when others => null;
1018 if not Is_Generic_Type (Ltyp) then
1019 case Compile_Time_Compare (Type_Low_Bound (Ltyp), R,
1021 Assume_Valid, Rec => True)
1023 when GT => return GT;
1024 when GE => return GE;
1025 when EQ => return GE;
1026 when others => null;
1029 case Compile_Time_Compare (Type_High_Bound (Ltyp), R,
1031 Assume_Valid, Rec => True)
1033 when LT => return LT;
1034 when LE => return LE;
1035 when EQ => return LE;
1036 when others => null;
1041 -- Next attempt is to decompose the expressions to extract
1042 -- a constant offset resulting from the use of any of the forms:
1049 -- Then we see if the two expressions are the same value, and if so
1050 -- the result is obtained by comparing the offsets.
1059 Compare_Decompose (L, Lnode, Loffs);
1060 Compare_Decompose (R, Rnode, Roffs);
1062 if Is_Same_Value (Lnode, Rnode) then
1063 if Loffs = Roffs then
1066 elsif Loffs < Roffs then
1067 Diff.all := Roffs - Loffs;
1071 Diff.all := Loffs - Roffs;
1077 -- Next attempt is to see if we have an entity compared with a
1078 -- compile time known value, where there is a current value
1079 -- conditional for the entity which can tell us the result.
1083 -- Entity variable (left operand)
1086 -- Value (right operand)
1089 -- If False, we have reversed the operands
1092 -- Comparison operator kind from Get_Current_Value_Condition call
1095 -- Value from Get_Current_Value_Condition call
1100 Result : Compare_Result;
1101 -- Known result before inversion
1104 if Is_Entity_Name (L)
1105 and then Compile_Time_Known_Value (R)
1108 Val := Expr_Value (R);
1111 elsif Is_Entity_Name (R)
1112 and then Compile_Time_Known_Value (L)
1115 Val := Expr_Value (L);
1118 -- That was the last chance at finding a compile time result
1124 Get_Current_Value_Condition (Var, Op, Opn);
1126 -- That was the last chance, so if we got nothing return
1132 Opv := Expr_Value (Opn);
1134 -- We got a comparison, so we might have something interesting
1136 -- Convert LE to LT and GE to GT, just so we have fewer cases
1138 if Op = N_Op_Le then
1142 elsif Op = N_Op_Ge then
1147 -- Deal with equality case
1149 if Op = N_Op_Eq then
1152 elsif Opv < Val then
1158 -- Deal with inequality case
1160 elsif Op = N_Op_Ne then
1167 -- Deal with greater than case
1169 elsif Op = N_Op_Gt then
1172 elsif Opv = Val - 1 then
1178 -- Deal with less than case
1180 else pragma Assert (Op = N_Op_Lt);
1183 elsif Opv = Val + 1 then
1190 -- Deal with inverting result
1194 when GT => return LT;
1195 when GE => return LE;
1196 when LT => return GT;
1197 when LE => return GE;
1198 when others => return Result;
1205 end Compile_Time_Compare;
1207 -------------------------------
1208 -- Compile_Time_Known_Bounds --
1209 -------------------------------
1211 function Compile_Time_Known_Bounds (T : Entity_Id) return Boolean is
1216 if not Is_Array_Type (T) then
1220 Indx := First_Index (T);
1221 while Present (Indx) loop
1222 Typ := Underlying_Type (Etype (Indx));
1224 -- Never look at junk bounds of a generic type
1226 if Is_Generic_Type (Typ) then
1230 -- Otherwise check bounds for compile time known
1232 if not Compile_Time_Known_Value (Type_Low_Bound (Typ)) then
1234 elsif not Compile_Time_Known_Value (Type_High_Bound (Typ)) then
1242 end Compile_Time_Known_Bounds;
1244 ------------------------------
1245 -- Compile_Time_Known_Value --
1246 ------------------------------
1248 function Compile_Time_Known_Value (Op : Node_Id) return Boolean is
1249 K : constant Node_Kind := Nkind (Op);
1250 CV_Ent : CV_Entry renames CV_Cache (Nat (Op) mod CV_Cache_Size);
1253 -- Never known at compile time if bad type or raises constraint error
1254 -- or empty (latter case occurs only as a result of a previous error)
1258 or else Etype (Op) = Any_Type
1259 or else Raises_Constraint_Error (Op)
1264 -- If this is not a static expression or a null literal, and we are in
1265 -- configurable run-time mode, then we consider it not known at compile
1266 -- time. This avoids anomalies where whether something is allowed with a
1267 -- given configurable run-time library depends on how good the compiler
1268 -- is at optimizing and knowing that things are constant when they are
1271 if Configurable_Run_Time_Mode
1272 and then K /= N_Null
1273 and then not Is_Static_Expression (Op)
1278 -- If we have an entity name, then see if it is the name of a constant
1279 -- and if so, test the corresponding constant value, or the name of
1280 -- an enumeration literal, which is always a constant.
1282 if Present (Etype (Op)) and then Is_Entity_Name (Op) then
1284 E : constant Entity_Id := Entity (Op);
1288 -- Never known at compile time if it is a packed array value.
1289 -- We might want to try to evaluate these at compile time one
1290 -- day, but we do not make that attempt now.
1292 if Is_Packed_Array_Type (Etype (Op)) then
1296 if Ekind (E) = E_Enumeration_Literal then
1299 elsif Ekind (E) = E_Constant then
1300 V := Constant_Value (E);
1301 return Present (V) and then Compile_Time_Known_Value (V);
1305 -- We have a value, see if it is compile time known
1308 -- Integer literals are worth storing in the cache
1310 if K = N_Integer_Literal then
1312 CV_Ent.V := Intval (Op);
1315 -- Other literals and NULL are known at compile time
1318 K = N_Character_Literal
1322 K = N_String_Literal
1328 -- Any reference to Null_Parameter is known at compile time. No
1329 -- other attribute references (that have not already been folded)
1330 -- are known at compile time.
1332 elsif K = N_Attribute_Reference then
1333 return Attribute_Name (Op) = Name_Null_Parameter;
1337 -- If we fall through, not known at compile time
1341 -- If we get an exception while trying to do this test, then some error
1342 -- has occurred, and we simply say that the value is not known after all
1347 end Compile_Time_Known_Value;
1349 --------------------------------------
1350 -- Compile_Time_Known_Value_Or_Aggr --
1351 --------------------------------------
1353 function Compile_Time_Known_Value_Or_Aggr (Op : Node_Id) return Boolean is
1355 -- If we have an entity name, then see if it is the name of a constant
1356 -- and if so, test the corresponding constant value, or the name of
1357 -- an enumeration literal, which is always a constant.
1359 if Is_Entity_Name (Op) then
1361 E : constant Entity_Id := Entity (Op);
1365 if Ekind (E) = E_Enumeration_Literal then
1368 elsif Ekind (E) /= E_Constant then
1372 V := Constant_Value (E);
1374 and then Compile_Time_Known_Value_Or_Aggr (V);
1378 -- We have a value, see if it is compile time known
1381 if Compile_Time_Known_Value (Op) then
1384 elsif Nkind (Op) = N_Aggregate then
1386 if Present (Expressions (Op)) then
1391 Expr := First (Expressions (Op));
1392 while Present (Expr) loop
1393 if not Compile_Time_Known_Value_Or_Aggr (Expr) then
1402 if Present (Component_Associations (Op)) then
1407 Cass := First (Component_Associations (Op));
1408 while Present (Cass) loop
1410 Compile_Time_Known_Value_Or_Aggr (Expression (Cass))
1422 -- All other types of values are not known at compile time
1429 end Compile_Time_Known_Value_Or_Aggr;
1435 -- This is only called for actuals of functions that are not predefined
1436 -- operators (which have already been rewritten as operators at this
1437 -- stage), so the call can never be folded, and all that needs doing for
1438 -- the actual is to do the check for a non-static context.
1440 procedure Eval_Actual (N : Node_Id) is
1442 Check_Non_Static_Context (N);
1445 --------------------
1446 -- Eval_Allocator --
1447 --------------------
1449 -- Allocators are never static, so all we have to do is to do the
1450 -- check for a non-static context if an expression is present.
1452 procedure Eval_Allocator (N : Node_Id) is
1453 Expr : constant Node_Id := Expression (N);
1456 if Nkind (Expr) = N_Qualified_Expression then
1457 Check_Non_Static_Context (Expression (Expr));
1461 ------------------------
1462 -- Eval_Arithmetic_Op --
1463 ------------------------
1465 -- Arithmetic operations are static functions, so the result is static
1466 -- if both operands are static (RM 4.9(7), 4.9(20)).
1468 procedure Eval_Arithmetic_Op (N : Node_Id) is
1469 Left : constant Node_Id := Left_Opnd (N);
1470 Right : constant Node_Id := Right_Opnd (N);
1471 Ltype : constant Entity_Id := Etype (Left);
1472 Rtype : constant Entity_Id := Etype (Right);
1473 Otype : Entity_Id := Empty;
1478 -- If not foldable we are done
1480 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1486 if Is_Universal_Numeric_Type (Etype (Left))
1488 Is_Universal_Numeric_Type (Etype (Right))
1490 Otype := Find_Universal_Operator_Type (N);
1493 -- Fold for cases where both operands are of integer type
1495 if Is_Integer_Type (Ltype) and then Is_Integer_Type (Rtype) then
1497 Left_Int : constant Uint := Expr_Value (Left);
1498 Right_Int : constant Uint := Expr_Value (Right);
1505 Result := Left_Int + Right_Int;
1507 when N_Op_Subtract =>
1508 Result := Left_Int - Right_Int;
1510 when N_Op_Multiply =>
1513 (Num_Bits (Left_Int) + Num_Bits (Right_Int)))
1515 Result := Left_Int * Right_Int;
1522 -- The exception Constraint_Error is raised by integer
1523 -- division, rem and mod if the right operand is zero.
1525 if Right_Int = 0 then
1526 Apply_Compile_Time_Constraint_Error
1527 (N, "division by zero",
1533 Result := Left_Int / Right_Int;
1538 -- The exception Constraint_Error is raised by integer
1539 -- division, rem and mod if the right operand is zero.
1541 if Right_Int = 0 then
1542 Apply_Compile_Time_Constraint_Error
1543 (N, "mod with zero divisor",
1548 Result := Left_Int mod Right_Int;
1553 -- The exception Constraint_Error is raised by integer
1554 -- division, rem and mod if the right operand is zero.
1556 if Right_Int = 0 then
1557 Apply_Compile_Time_Constraint_Error
1558 (N, "rem with zero divisor",
1564 Result := Left_Int rem Right_Int;
1568 raise Program_Error;
1571 -- Adjust the result by the modulus if the type is a modular type
1573 if Is_Modular_Integer_Type (Ltype) then
1574 Result := Result mod Modulus (Ltype);
1576 -- For a signed integer type, check non-static overflow
1578 elsif (not Stat) and then Is_Signed_Integer_Type (Ltype) then
1580 BT : constant Entity_Id := Base_Type (Ltype);
1581 Lo : constant Uint := Expr_Value (Type_Low_Bound (BT));
1582 Hi : constant Uint := Expr_Value (Type_High_Bound (BT));
1584 if Result < Lo or else Result > Hi then
1585 Apply_Compile_Time_Constraint_Error
1586 (N, "value not in range of }?",
1587 CE_Overflow_Check_Failed,
1594 -- If we get here we can fold the result
1596 Fold_Uint (N, Result, Stat);
1599 -- Cases where at least one operand is a real. We handle the cases of
1600 -- both reals, or mixed/real integer cases (the latter happen only for
1601 -- divide and multiply, and the result is always real).
1603 elsif Is_Real_Type (Ltype) or else Is_Real_Type (Rtype) then
1610 if Is_Real_Type (Ltype) then
1611 Left_Real := Expr_Value_R (Left);
1613 Left_Real := UR_From_Uint (Expr_Value (Left));
1616 if Is_Real_Type (Rtype) then
1617 Right_Real := Expr_Value_R (Right);
1619 Right_Real := UR_From_Uint (Expr_Value (Right));
1622 if Nkind (N) = N_Op_Add then
1623 Result := Left_Real + Right_Real;
1625 elsif Nkind (N) = N_Op_Subtract then
1626 Result := Left_Real - Right_Real;
1628 elsif Nkind (N) = N_Op_Multiply then
1629 Result := Left_Real * Right_Real;
1631 else pragma Assert (Nkind (N) = N_Op_Divide);
1632 if UR_Is_Zero (Right_Real) then
1633 Apply_Compile_Time_Constraint_Error
1634 (N, "division by zero", CE_Divide_By_Zero);
1638 Result := Left_Real / Right_Real;
1641 Fold_Ureal (N, Result, Stat);
1645 -- If the operator was resolved to a specific type, make sure that type
1646 -- is frozen even if the expression is folded into a literal (which has
1647 -- a universal type).
1649 if Present (Otype) then
1650 Freeze_Before (N, Otype);
1652 end Eval_Arithmetic_Op;
1654 ----------------------------
1655 -- Eval_Character_Literal --
1656 ----------------------------
1658 -- Nothing to be done!
1660 procedure Eval_Character_Literal (N : Node_Id) is
1661 pragma Warnings (Off, N);
1664 end Eval_Character_Literal;
1670 -- Static function calls are either calls to predefined operators
1671 -- with static arguments, or calls to functions that rename a literal.
1672 -- Only the latter case is handled here, predefined operators are
1673 -- constant-folded elsewhere.
1675 -- If the function is itself inherited (see 7423-001) the literal of
1676 -- the parent type must be explicitly converted to the return type
1679 procedure Eval_Call (N : Node_Id) is
1680 Loc : constant Source_Ptr := Sloc (N);
1681 Typ : constant Entity_Id := Etype (N);
1685 if Nkind (N) = N_Function_Call
1686 and then No (Parameter_Associations (N))
1687 and then Is_Entity_Name (Name (N))
1688 and then Present (Alias (Entity (Name (N))))
1689 and then Is_Enumeration_Type (Base_Type (Typ))
1691 Lit := Ultimate_Alias (Entity (Name (N)));
1693 if Ekind (Lit) = E_Enumeration_Literal then
1694 if Base_Type (Etype (Lit)) /= Base_Type (Typ) then
1696 (N, Convert_To (Typ, New_Occurrence_Of (Lit, Loc)));
1698 Rewrite (N, New_Occurrence_Of (Lit, Loc));
1706 --------------------------
1707 -- Eval_Case_Expression --
1708 --------------------------
1710 -- Right now we do not attempt folding of any case expressions, and the
1711 -- language does not require it, so the only required processing is to
1712 -- do the check for all expressions appearing in the case expression.
1714 procedure Eval_Case_Expression (N : Node_Id) is
1718 Check_Non_Static_Context (Expression (N));
1720 Alt := First (Alternatives (N));
1721 while Present (Alt) loop
1722 Check_Non_Static_Context (Expression (Alt));
1725 end Eval_Case_Expression;
1727 ------------------------
1728 -- Eval_Concatenation --
1729 ------------------------
1731 -- Concatenation is a static function, so the result is static if both
1732 -- operands are static (RM 4.9(7), 4.9(21)).
1734 procedure Eval_Concatenation (N : Node_Id) is
1735 Left : constant Node_Id := Left_Opnd (N);
1736 Right : constant Node_Id := Right_Opnd (N);
1737 C_Typ : constant Entity_Id := Root_Type (Component_Type (Etype (N)));
1742 -- Concatenation is never static in Ada 83, so if Ada 83 check operand
1743 -- non-static context.
1745 if Ada_Version = Ada_83
1746 and then Comes_From_Source (N)
1748 Check_Non_Static_Context (Left);
1749 Check_Non_Static_Context (Right);
1753 -- If not foldable we are done. In principle concatenation that yields
1754 -- any string type is static (i.e. an array type of character types).
1755 -- However, character types can include enumeration literals, and
1756 -- concatenation in that case cannot be described by a literal, so we
1757 -- only consider the operation static if the result is an array of
1758 -- (a descendant of) a predefined character type.
1760 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1762 if not (Is_Standard_Character_Type (C_Typ) and then Fold) then
1763 Set_Is_Static_Expression (N, False);
1767 -- Compile time string concatenation
1769 -- ??? Note that operands that are aggregates can be marked as static,
1770 -- so we should attempt at a later stage to fold concatenations with
1774 Left_Str : constant Node_Id := Get_String_Val (Left);
1776 Right_Str : constant Node_Id := Get_String_Val (Right);
1777 Folded_Val : String_Id;
1780 -- Establish new string literal, and store left operand. We make
1781 -- sure to use the special Start_String that takes an operand if
1782 -- the left operand is a string literal. Since this is optimized
1783 -- in the case where that is the most recently created string
1784 -- literal, we ensure efficient time/space behavior for the
1785 -- case of a concatenation of a series of string literals.
1787 if Nkind (Left_Str) = N_String_Literal then
1788 Left_Len := String_Length (Strval (Left_Str));
1790 -- If the left operand is the empty string, and the right operand
1791 -- is a string literal (the case of "" & "..."), the result is the
1792 -- value of the right operand. This optimization is important when
1793 -- Is_Folded_In_Parser, to avoid copying an enormous right
1796 if Left_Len = 0 and then Nkind (Right_Str) = N_String_Literal then
1797 Folded_Val := Strval (Right_Str);
1799 Start_String (Strval (Left_Str));
1804 Store_String_Char (UI_To_CC (Char_Literal_Value (Left_Str)));
1808 -- Now append the characters of the right operand, unless we
1809 -- optimized the "" & "..." case above.
1811 if Nkind (Right_Str) = N_String_Literal then
1812 if Left_Len /= 0 then
1813 Store_String_Chars (Strval (Right_Str));
1814 Folded_Val := End_String;
1817 Store_String_Char (UI_To_CC (Char_Literal_Value (Right_Str)));
1818 Folded_Val := End_String;
1821 Set_Is_Static_Expression (N, Stat);
1825 -- If left operand is the empty string, the result is the
1826 -- right operand, including its bounds if anomalous.
1829 and then Is_Array_Type (Etype (Right))
1830 and then Etype (Right) /= Any_String
1832 Set_Etype (N, Etype (Right));
1835 Fold_Str (N, Folded_Val, Static => True);
1838 end Eval_Concatenation;
1840 ---------------------------------
1841 -- Eval_Conditional_Expression --
1842 ---------------------------------
1844 -- We can fold to a static expression if the condition and both constituent
1845 -- expressions are static. Otherwise, the only required processing is to do
1846 -- the check for non-static context for the then and else expressions.
1848 procedure Eval_Conditional_Expression (N : Node_Id) is
1849 Condition : constant Node_Id := First (Expressions (N));
1850 Then_Expr : constant Node_Id := Next (Condition);
1851 Else_Expr : constant Node_Id := Next (Then_Expr);
1853 Non_Result : Node_Id;
1855 Rstat : constant Boolean :=
1856 Is_Static_Expression (Condition)
1858 Is_Static_Expression (Then_Expr)
1860 Is_Static_Expression (Else_Expr);
1863 -- If any operand is Any_Type, just propagate to result and do not try
1864 -- to fold, this prevents cascaded errors.
1866 if Etype (Condition) = Any_Type or else
1867 Etype (Then_Expr) = Any_Type or else
1868 Etype (Else_Expr) = Any_Type
1870 Set_Etype (N, Any_Type);
1871 Set_Is_Static_Expression (N, False);
1874 -- Static case where we can fold. Note that we don't try to fold cases
1875 -- where the condition is known at compile time, but the result is
1876 -- non-static. This avoids possible cases of infinite recursion where
1877 -- the expander puts in a redundant test and we remove it. Instead we
1878 -- deal with these cases in the expander.
1882 -- Select result operand
1884 if Is_True (Expr_Value (Condition)) then
1885 Result := Then_Expr;
1886 Non_Result := Else_Expr;
1888 Result := Else_Expr;
1889 Non_Result := Then_Expr;
1892 -- Note that it does not matter if the non-result operand raises a
1893 -- Constraint_Error, but if the result raises constraint error then
1894 -- we replace the node with a raise constraint error. This will
1895 -- properly propagate Raises_Constraint_Error since this flag is
1898 if Raises_Constraint_Error (Result) then
1899 Rewrite_In_Raise_CE (N, Result);
1900 Check_Non_Static_Context (Non_Result);
1902 -- Otherwise the result operand replaces the original node
1905 Rewrite (N, Relocate_Node (Result));
1908 -- Case of condition not known at compile time
1911 Check_Non_Static_Context (Condition);
1912 Check_Non_Static_Context (Then_Expr);
1913 Check_Non_Static_Context (Else_Expr);
1916 Set_Is_Static_Expression (N, Rstat);
1917 end Eval_Conditional_Expression;
1919 ----------------------
1920 -- Eval_Entity_Name --
1921 ----------------------
1923 -- This procedure is used for identifiers and expanded names other than
1924 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
1925 -- static if they denote a static constant (RM 4.9(6)) or if the name
1926 -- denotes an enumeration literal (RM 4.9(22)).
1928 procedure Eval_Entity_Name (N : Node_Id) is
1929 Def_Id : constant Entity_Id := Entity (N);
1933 -- Enumeration literals are always considered to be constants
1934 -- and cannot raise constraint error (RM 4.9(22)).
1936 if Ekind (Def_Id) = E_Enumeration_Literal then
1937 Set_Is_Static_Expression (N);
1940 -- A name is static if it denotes a static constant (RM 4.9(5)), and
1941 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
1942 -- it does not violate 10.2.1(8) here, since this is not a variable.
1944 elsif Ekind (Def_Id) = E_Constant then
1946 -- Deferred constants must always be treated as nonstatic
1947 -- outside the scope of their full view.
1949 if Present (Full_View (Def_Id))
1950 and then not In_Open_Scopes (Scope (Def_Id))
1954 Val := Constant_Value (Def_Id);
1957 if Present (Val) then
1958 Set_Is_Static_Expression
1959 (N, Is_Static_Expression (Val)
1960 and then Is_Static_Subtype (Etype (Def_Id)));
1961 Set_Raises_Constraint_Error (N, Raises_Constraint_Error (Val));
1963 if not Is_Static_Expression (N)
1964 and then not Is_Generic_Type (Etype (N))
1966 Validate_Static_Object_Name (N);
1973 -- Fall through if the name is not static
1975 Validate_Static_Object_Name (N);
1976 end Eval_Entity_Name;
1978 ----------------------------
1979 -- Eval_Indexed_Component --
1980 ----------------------------
1982 -- Indexed components are never static, so we need to perform the check
1983 -- for non-static context on the index values. Then, we check if the
1984 -- value can be obtained at compile time, even though it is non-static.
1986 procedure Eval_Indexed_Component (N : Node_Id) is
1990 -- Check for non-static context on index values
1992 Expr := First (Expressions (N));
1993 while Present (Expr) loop
1994 Check_Non_Static_Context (Expr);
1998 -- If the indexed component appears in an object renaming declaration
1999 -- then we do not want to try to evaluate it, since in this case we
2000 -- need the identity of the array element.
2002 if Nkind (Parent (N)) = N_Object_Renaming_Declaration then
2005 -- Similarly if the indexed component appears as the prefix of an
2006 -- attribute we don't want to evaluate it, because at least for
2007 -- some cases of attributes we need the identify (e.g. Access, Size)
2009 elsif Nkind (Parent (N)) = N_Attribute_Reference then
2013 -- Note: there are other cases, such as the left side of an assignment,
2014 -- or an OUT parameter for a call, where the replacement results in the
2015 -- illegal use of a constant, But these cases are illegal in the first
2016 -- place, so the replacement, though silly, is harmless.
2018 -- Now see if this is a constant array reference
2020 if List_Length (Expressions (N)) = 1
2021 and then Is_Entity_Name (Prefix (N))
2022 and then Ekind (Entity (Prefix (N))) = E_Constant
2023 and then Present (Constant_Value (Entity (Prefix (N))))
2026 Loc : constant Source_Ptr := Sloc (N);
2027 Arr : constant Node_Id := Constant_Value (Entity (Prefix (N)));
2028 Sub : constant Node_Id := First (Expressions (N));
2034 -- Linear one's origin subscript value for array reference
2037 -- Lower bound of the first array index
2040 -- Value from constant array
2043 Atyp := Etype (Arr);
2045 if Is_Access_Type (Atyp) then
2046 Atyp := Designated_Type (Atyp);
2049 -- If we have an array type (we should have but perhaps there are
2050 -- error cases where this is not the case), then see if we can do
2051 -- a constant evaluation of the array reference.
2053 if Is_Array_Type (Atyp) and then Atyp /= Any_Composite then
2054 if Ekind (Atyp) = E_String_Literal_Subtype then
2055 Lbd := String_Literal_Low_Bound (Atyp);
2057 Lbd := Type_Low_Bound (Etype (First_Index (Atyp)));
2060 if Compile_Time_Known_Value (Sub)
2061 and then Nkind (Arr) = N_Aggregate
2062 and then Compile_Time_Known_Value (Lbd)
2063 and then Is_Discrete_Type (Component_Type (Atyp))
2065 Lin := UI_To_Int (Expr_Value (Sub) - Expr_Value (Lbd)) + 1;
2067 if List_Length (Expressions (Arr)) >= Lin then
2068 Elm := Pick (Expressions (Arr), Lin);
2070 -- If the resulting expression is compile time known,
2071 -- then we can rewrite the indexed component with this
2072 -- value, being sure to mark the result as non-static.
2073 -- We also reset the Sloc, in case this generates an
2074 -- error later on (e.g. 136'Access).
2076 if Compile_Time_Known_Value (Elm) then
2077 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
2078 Set_Is_Static_Expression (N, False);
2083 -- We can also constant-fold if the prefix is a string literal.
2084 -- This will be useful in an instantiation or an inlining.
2086 elsif Compile_Time_Known_Value (Sub)
2087 and then Nkind (Arr) = N_String_Literal
2088 and then Compile_Time_Known_Value (Lbd)
2089 and then Expr_Value (Lbd) = 1
2090 and then Expr_Value (Sub) <=
2091 String_Literal_Length (Etype (Arr))
2094 C : constant Char_Code :=
2095 Get_String_Char (Strval (Arr),
2096 UI_To_Int (Expr_Value (Sub)));
2098 Set_Character_Literal_Name (C);
2101 Make_Character_Literal (Loc,
2103 Char_Literal_Value => UI_From_CC (C));
2104 Set_Etype (Elm, Component_Type (Atyp));
2105 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
2106 Set_Is_Static_Expression (N, False);
2112 end Eval_Indexed_Component;
2114 --------------------------
2115 -- Eval_Integer_Literal --
2116 --------------------------
2118 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2119 -- as static by the analyzer. The reason we did it that early is to allow
2120 -- the possibility of turning off the Is_Static_Expression flag after
2121 -- analysis, but before resolution, when integer literals are generated in
2122 -- the expander that do not correspond to static expressions.
2124 procedure Eval_Integer_Literal (N : Node_Id) is
2125 T : constant Entity_Id := Etype (N);
2127 function In_Any_Integer_Context return Boolean;
2128 -- If the literal is resolved with a specific type in a context where
2129 -- the expected type is Any_Integer, there are no range checks on the
2130 -- literal. By the time the literal is evaluated, it carries the type
2131 -- imposed by the enclosing expression, and we must recover the context
2132 -- to determine that Any_Integer is meant.
2134 ----------------------------
2135 -- In_Any_Integer_Context --
2136 ----------------------------
2138 function In_Any_Integer_Context return Boolean is
2139 Par : constant Node_Id := Parent (N);
2140 K : constant Node_Kind := Nkind (Par);
2143 -- Any_Integer also appears in digits specifications for real types,
2144 -- but those have bounds smaller that those of any integer base type,
2145 -- so we can safely ignore these cases.
2147 return K = N_Number_Declaration
2148 or else K = N_Attribute_Reference
2149 or else K = N_Attribute_Definition_Clause
2150 or else K = N_Modular_Type_Definition
2151 or else K = N_Signed_Integer_Type_Definition;
2152 end In_Any_Integer_Context;
2154 -- Start of processing for Eval_Integer_Literal
2158 -- If the literal appears in a non-expression context, then it is
2159 -- certainly appearing in a non-static context, so check it. This is
2160 -- actually a redundant check, since Check_Non_Static_Context would
2161 -- check it, but it seems worth while avoiding the call.
2163 if Nkind (Parent (N)) not in N_Subexpr
2164 and then not In_Any_Integer_Context
2166 Check_Non_Static_Context (N);
2169 -- Modular integer literals must be in their base range
2171 if Is_Modular_Integer_Type (T)
2172 and then Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True)
2176 end Eval_Integer_Literal;
2178 ---------------------
2179 -- Eval_Logical_Op --
2180 ---------------------
2182 -- Logical operations are static functions, so the result is potentially
2183 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2185 procedure Eval_Logical_Op (N : Node_Id) is
2186 Left : constant Node_Id := Left_Opnd (N);
2187 Right : constant Node_Id := Right_Opnd (N);
2192 -- If not foldable we are done
2194 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2200 -- Compile time evaluation of logical operation
2203 Left_Int : constant Uint := Expr_Value (Left);
2204 Right_Int : constant Uint := Expr_Value (Right);
2207 -- VMS includes bitwise operations on signed types
2209 if Is_Modular_Integer_Type (Etype (N))
2210 or else Is_VMS_Operator (Entity (N))
2213 Left_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
2214 Right_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
2217 To_Bits (Left_Int, Left_Bits);
2218 To_Bits (Right_Int, Right_Bits);
2220 -- Note: should really be able to use array ops instead of
2221 -- these loops, but they weren't working at the time ???
2223 if Nkind (N) = N_Op_And then
2224 for J in Left_Bits'Range loop
2225 Left_Bits (J) := Left_Bits (J) and Right_Bits (J);
2228 elsif Nkind (N) = N_Op_Or then
2229 for J in Left_Bits'Range loop
2230 Left_Bits (J) := Left_Bits (J) or Right_Bits (J);
2234 pragma Assert (Nkind (N) = N_Op_Xor);
2236 for J in Left_Bits'Range loop
2237 Left_Bits (J) := Left_Bits (J) xor Right_Bits (J);
2241 Fold_Uint (N, From_Bits (Left_Bits, Etype (N)), Stat);
2245 pragma Assert (Is_Boolean_Type (Etype (N)));
2247 if Nkind (N) = N_Op_And then
2249 Test (Is_True (Left_Int) and then Is_True (Right_Int)), Stat);
2251 elsif Nkind (N) = N_Op_Or then
2253 Test (Is_True (Left_Int) or else Is_True (Right_Int)), Stat);
2256 pragma Assert (Nkind (N) = N_Op_Xor);
2258 Test (Is_True (Left_Int) xor Is_True (Right_Int)), Stat);
2262 end Eval_Logical_Op;
2264 ------------------------
2265 -- Eval_Membership_Op --
2266 ------------------------
2268 -- A membership test is potentially static if the expression is static, and
2269 -- the range is a potentially static range, or is a subtype mark denoting a
2270 -- static subtype (RM 4.9(12)).
2272 procedure Eval_Membership_Op (N : Node_Id) is
2273 Left : constant Node_Id := Left_Opnd (N);
2274 Right : constant Node_Id := Right_Opnd (N);
2283 -- Ignore if error in either operand, except to make sure that Any_Type
2284 -- is properly propagated to avoid junk cascaded errors.
2286 if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
2287 Set_Etype (N, Any_Type);
2291 -- Ignore if types involved have predicates
2293 if Present (Predicate_Function (Etype (Left)))
2295 Present (Predicate_Function (Etype (Right)))
2300 -- Case of right operand is a subtype name
2302 if Is_Entity_Name (Right) then
2303 Def_Id := Entity (Right);
2305 if (Is_Scalar_Type (Def_Id) or else Is_String_Type (Def_Id))
2306 and then Is_OK_Static_Subtype (Def_Id)
2308 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
2310 if not Fold or else not Stat then
2314 Check_Non_Static_Context (Left);
2318 -- For string membership tests we will check the length further on
2320 if not Is_String_Type (Def_Id) then
2321 Lo := Type_Low_Bound (Def_Id);
2322 Hi := Type_High_Bound (Def_Id);
2329 -- Case of right operand is a range
2332 if Is_Static_Range (Right) then
2333 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
2335 if not Fold or else not Stat then
2338 -- If one bound of range raises CE, then don't try to fold
2340 elsif not Is_OK_Static_Range (Right) then
2341 Check_Non_Static_Context (Left);
2346 Check_Non_Static_Context (Left);
2350 -- Here we know range is an OK static range
2352 Lo := Low_Bound (Right);
2353 Hi := High_Bound (Right);
2356 -- For strings we check that the length of the string expression is
2357 -- compatible with the string subtype if the subtype is constrained,
2358 -- or if unconstrained then the test is always true.
2360 if Is_String_Type (Etype (Right)) then
2361 if not Is_Constrained (Etype (Right)) then
2366 Typlen : constant Uint := String_Type_Len (Etype (Right));
2367 Strlen : constant Uint :=
2369 (String_Length (Strval (Get_String_Val (Left))));
2371 Result := (Typlen = Strlen);
2375 -- Fold the membership test. We know we have a static range and Lo and
2376 -- Hi are set to the expressions for the end points of this range.
2378 elsif Is_Real_Type (Etype (Right)) then
2380 Leftval : constant Ureal := Expr_Value_R (Left);
2383 Result := Expr_Value_R (Lo) <= Leftval
2384 and then Leftval <= Expr_Value_R (Hi);
2389 Leftval : constant Uint := Expr_Value (Left);
2392 Result := Expr_Value (Lo) <= Leftval
2393 and then Leftval <= Expr_Value (Hi);
2397 if Nkind (N) = N_Not_In then
2398 Result := not Result;
2401 Fold_Uint (N, Test (Result), True);
2403 Warn_On_Known_Condition (N);
2404 end Eval_Membership_Op;
2406 ------------------------
2407 -- Eval_Named_Integer --
2408 ------------------------
2410 procedure Eval_Named_Integer (N : Node_Id) is
2413 Expr_Value (Expression (Declaration_Node (Entity (N)))), True);
2414 end Eval_Named_Integer;
2416 ---------------------
2417 -- Eval_Named_Real --
2418 ---------------------
2420 procedure Eval_Named_Real (N : Node_Id) is
2423 Expr_Value_R (Expression (Declaration_Node (Entity (N)))), True);
2424 end Eval_Named_Real;
2430 -- Exponentiation is a static functions, so the result is potentially
2431 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2433 procedure Eval_Op_Expon (N : Node_Id) is
2434 Left : constant Node_Id := Left_Opnd (N);
2435 Right : constant Node_Id := Right_Opnd (N);
2440 -- If not foldable we are done
2442 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2448 -- Fold exponentiation operation
2451 Right_Int : constant Uint := Expr_Value (Right);
2456 if Is_Integer_Type (Etype (Left)) then
2458 Left_Int : constant Uint := Expr_Value (Left);
2462 -- Exponentiation of an integer raises Constraint_Error for a
2463 -- negative exponent (RM 4.5.6).
2465 if Right_Int < 0 then
2466 Apply_Compile_Time_Constraint_Error
2467 (N, "integer exponent negative",
2468 CE_Range_Check_Failed,
2473 if OK_Bits (N, Num_Bits (Left_Int) * Right_Int) then
2474 Result := Left_Int ** Right_Int;
2479 if Is_Modular_Integer_Type (Etype (N)) then
2480 Result := Result mod Modulus (Etype (N));
2483 Fold_Uint (N, Result, Stat);
2491 Left_Real : constant Ureal := Expr_Value_R (Left);
2494 -- Cannot have a zero base with a negative exponent
2496 if UR_Is_Zero (Left_Real) then
2498 if Right_Int < 0 then
2499 Apply_Compile_Time_Constraint_Error
2500 (N, "zero ** negative integer",
2501 CE_Range_Check_Failed,
2505 Fold_Ureal (N, Ureal_0, Stat);
2509 Fold_Ureal (N, Left_Real ** Right_Int, Stat);
2520 -- The not operation is a static functions, so the result is potentially
2521 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
2523 procedure Eval_Op_Not (N : Node_Id) is
2524 Right : constant Node_Id := Right_Opnd (N);
2529 -- If not foldable we are done
2531 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
2537 -- Fold not operation
2540 Rint : constant Uint := Expr_Value (Right);
2541 Typ : constant Entity_Id := Etype (N);
2544 -- Negation is equivalent to subtracting from the modulus minus one.
2545 -- For a binary modulus this is equivalent to the ones-complement of
2546 -- the original value. For non-binary modulus this is an arbitrary
2547 -- but consistent definition.
2549 if Is_Modular_Integer_Type (Typ) then
2550 Fold_Uint (N, Modulus (Typ) - 1 - Rint, Stat);
2553 pragma Assert (Is_Boolean_Type (Typ));
2554 Fold_Uint (N, Test (not Is_True (Rint)), Stat);
2557 Set_Is_Static_Expression (N, Stat);
2561 -------------------------------
2562 -- Eval_Qualified_Expression --
2563 -------------------------------
2565 -- A qualified expression is potentially static if its subtype mark denotes
2566 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2568 procedure Eval_Qualified_Expression (N : Node_Id) is
2569 Operand : constant Node_Id := Expression (N);
2570 Target_Type : constant Entity_Id := Entity (Subtype_Mark (N));
2577 -- Can only fold if target is string or scalar and subtype is static.
2578 -- Also, do not fold if our parent is an allocator (this is because the
2579 -- qualified expression is really part of the syntactic structure of an
2580 -- allocator, and we do not want to end up with something that
2581 -- corresponds to "new 1" where the 1 is the result of folding a
2582 -- qualified expression).
2584 if not Is_Static_Subtype (Target_Type)
2585 or else Nkind (Parent (N)) = N_Allocator
2587 Check_Non_Static_Context (Operand);
2589 -- If operand is known to raise constraint_error, set the flag on the
2590 -- expression so it does not get optimized away.
2592 if Nkind (Operand) = N_Raise_Constraint_Error then
2593 Set_Raises_Constraint_Error (N);
2599 -- If not foldable we are done
2601 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
2606 -- Don't try fold if target type has constraint error bounds
2608 elsif not Is_OK_Static_Subtype (Target_Type) then
2609 Set_Raises_Constraint_Error (N);
2613 -- Here we will fold, save Print_In_Hex indication
2615 Hex := Nkind (Operand) = N_Integer_Literal
2616 and then Print_In_Hex (Operand);
2618 -- Fold the result of qualification
2620 if Is_Discrete_Type (Target_Type) then
2621 Fold_Uint (N, Expr_Value (Operand), Stat);
2623 -- Preserve Print_In_Hex indication
2625 if Hex and then Nkind (N) = N_Integer_Literal then
2626 Set_Print_In_Hex (N);
2629 elsif Is_Real_Type (Target_Type) then
2630 Fold_Ureal (N, Expr_Value_R (Operand), Stat);
2633 Fold_Str (N, Strval (Get_String_Val (Operand)), Stat);
2636 Set_Is_Static_Expression (N, False);
2638 Check_String_Literal_Length (N, Target_Type);
2644 -- The expression may be foldable but not static
2646 Set_Is_Static_Expression (N, Stat);
2648 if Is_Out_Of_Range (N, Etype (N), Assume_Valid => True) then
2651 end Eval_Qualified_Expression;
2653 -----------------------
2654 -- Eval_Real_Literal --
2655 -----------------------
2657 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2658 -- as static by the analyzer. The reason we did it that early is to allow
2659 -- the possibility of turning off the Is_Static_Expression flag after
2660 -- analysis, but before resolution, when integer literals are generated
2661 -- in the expander that do not correspond to static expressions.
2663 procedure Eval_Real_Literal (N : Node_Id) is
2664 PK : constant Node_Kind := Nkind (Parent (N));
2667 -- If the literal appears in a non-expression context and not as part of
2668 -- a number declaration, then it is appearing in a non-static context,
2671 if PK not in N_Subexpr and then PK /= N_Number_Declaration then
2672 Check_Non_Static_Context (N);
2674 end Eval_Real_Literal;
2676 ------------------------
2677 -- Eval_Relational_Op --
2678 ------------------------
2680 -- Relational operations are static functions, so the result is static if
2681 -- both operands are static (RM 4.9(7), 4.9(20)), except that for strings,
2682 -- the result is never static, even if the operands are.
2684 procedure Eval_Relational_Op (N : Node_Id) is
2685 Left : constant Node_Id := Left_Opnd (N);
2686 Right : constant Node_Id := Right_Opnd (N);
2687 Typ : constant Entity_Id := Etype (Left);
2688 Otype : Entity_Id := Empty;
2694 -- One special case to deal with first. If we can tell that the result
2695 -- will be false because the lengths of one or more index subtypes are
2696 -- compile time known and different, then we can replace the entire
2697 -- result by False. We only do this for one dimensional arrays, because
2698 -- the case of multi-dimensional arrays is rare and too much trouble! If
2699 -- one of the operands is an illegal aggregate, its type might still be
2700 -- an arbitrary composite type, so nothing to do.
2702 if Is_Array_Type (Typ)
2703 and then Typ /= Any_Composite
2704 and then Number_Dimensions (Typ) = 1
2705 and then (Nkind (N) = N_Op_Eq or else Nkind (N) = N_Op_Ne)
2707 if Raises_Constraint_Error (Left)
2708 or else Raises_Constraint_Error (Right)
2713 -- OK, we have the case where we may be able to do this fold
2715 Length_Mismatch : declare
2716 procedure Get_Static_Length (Op : Node_Id; Len : out Uint);
2717 -- If Op is an expression for a constrained array with a known at
2718 -- compile time length, then Len is set to this (non-negative
2719 -- length). Otherwise Len is set to minus 1.
2721 -----------------------
2722 -- Get_Static_Length --
2723 -----------------------
2725 procedure Get_Static_Length (Op : Node_Id; Len : out Uint) is
2729 -- First easy case string literal
2731 if Nkind (Op) = N_String_Literal then
2732 Len := UI_From_Int (String_Length (Strval (Op)));
2736 -- Second easy case, not constrained subtype, so no length
2738 if not Is_Constrained (Etype (Op)) then
2739 Len := Uint_Minus_1;
2745 T := Etype (First_Index (Etype (Op)));
2747 -- The simple case, both bounds are known at compile time
2749 if Is_Discrete_Type (T)
2751 Compile_Time_Known_Value (Type_Low_Bound (T))
2753 Compile_Time_Known_Value (Type_High_Bound (T))
2755 Len := UI_Max (Uint_0,
2756 Expr_Value (Type_High_Bound (T)) -
2757 Expr_Value (Type_Low_Bound (T)) + 1);
2761 -- A more complex case, where the bounds are of the form
2762 -- X [+/- K1] .. X [+/- K2]), where X is an expression that is
2763 -- either A'First or A'Last (with A an entity name), or X is an
2764 -- entity name, and the two X's are the same and K1 and K2 are
2765 -- known at compile time, in this case, the length can also be
2766 -- computed at compile time, even though the bounds are not
2767 -- known. A common case of this is e.g. (X'First .. X'First+5).
2769 Extract_Length : declare
2770 procedure Decompose_Expr
2772 Ent : out Entity_Id;
2773 Kind : out Character;
2775 -- Given an expression, see if is of the form above,
2776 -- X [+/- K]. If so Ent is set to the entity in X,
2777 -- Kind is 'F','L','E' for 'First/'Last/simple entity,
2778 -- and Cons is the value of K. If the expression is
2779 -- not of the required form, Ent is set to Empty.
2781 --------------------
2782 -- Decompose_Expr --
2783 --------------------
2785 procedure Decompose_Expr
2787 Ent : out Entity_Id;
2788 Kind : out Character;
2794 if Nkind (Expr) = N_Op_Add
2795 and then Compile_Time_Known_Value (Right_Opnd (Expr))
2797 Exp := Left_Opnd (Expr);
2798 Cons := Expr_Value (Right_Opnd (Expr));
2800 elsif Nkind (Expr) = N_Op_Subtract
2801 and then Compile_Time_Known_Value (Right_Opnd (Expr))
2803 Exp := Left_Opnd (Expr);
2804 Cons := -Expr_Value (Right_Opnd (Expr));
2806 -- If the bound is a constant created to remove side
2807 -- effects, recover original expression to see if it has
2808 -- one of the recognizable forms.
2810 elsif Nkind (Expr) = N_Identifier
2811 and then not Comes_From_Source (Entity (Expr))
2812 and then Ekind (Entity (Expr)) = E_Constant
2814 Nkind (Parent (Entity (Expr))) = N_Object_Declaration
2816 Exp := Expression (Parent (Entity (Expr)));
2817 Decompose_Expr (Exp, Ent, Kind, Cons);
2819 -- If original expression includes an entity, create a
2820 -- reference to it for use below.
2822 if Present (Ent) then
2823 Exp := New_Occurrence_Of (Ent, Sloc (Ent));
2831 -- At this stage Exp is set to the potential X
2833 if Nkind (Exp) = N_Attribute_Reference then
2834 if Attribute_Name (Exp) = Name_First then
2837 elsif Attribute_Name (Exp) = Name_Last then
2845 Exp := Prefix (Exp);
2851 if Is_Entity_Name (Exp)
2852 and then Present (Entity (Exp))
2854 Ent := Entity (Exp);
2862 Ent1, Ent2 : Entity_Id;
2863 Kind1, Kind2 : Character;
2864 Cons1, Cons2 : Uint;
2866 -- Start of processing for Extract_Length
2870 (Original_Node (Type_Low_Bound (T)), Ent1, Kind1, Cons1);
2872 (Original_Node (Type_High_Bound (T)), Ent2, Kind2, Cons2);
2875 and then Kind1 = Kind2
2876 and then Ent1 = Ent2
2878 Len := Cons2 - Cons1 + 1;
2880 Len := Uint_Minus_1;
2883 end Get_Static_Length;
2890 -- Start of processing for Length_Mismatch
2893 Get_Static_Length (Left, Len_L);
2894 Get_Static_Length (Right, Len_R);
2896 if Len_L /= Uint_Minus_1
2897 and then Len_R /= Uint_Minus_1
2898 and then Len_L /= Len_R
2900 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2901 Warn_On_Known_Condition (N);
2904 end Length_Mismatch;
2907 -- Test for expression being foldable
2909 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2911 -- Only comparisons of scalars can give static results. In particular,
2912 -- comparisons of strings never yield a static result, even if both
2913 -- operands are static strings.
2915 if not Is_Scalar_Type (Typ) then
2917 Set_Is_Static_Expression (N, False);
2920 -- For operators on universal numeric types called as functions with
2921 -- an explicit scope, determine appropriate specific numeric type, and
2922 -- diagnose possible ambiguity.
2924 if Is_Universal_Numeric_Type (Etype (Left))
2926 Is_Universal_Numeric_Type (Etype (Right))
2928 Otype := Find_Universal_Operator_Type (N);
2931 -- For static real type expressions, we cannot use Compile_Time_Compare
2932 -- since it worries about run-time results which are not exact.
2934 if Stat and then Is_Real_Type (Typ) then
2936 Left_Real : constant Ureal := Expr_Value_R (Left);
2937 Right_Real : constant Ureal := Expr_Value_R (Right);
2941 when N_Op_Eq => Result := (Left_Real = Right_Real);
2942 when N_Op_Ne => Result := (Left_Real /= Right_Real);
2943 when N_Op_Lt => Result := (Left_Real < Right_Real);
2944 when N_Op_Le => Result := (Left_Real <= Right_Real);
2945 when N_Op_Gt => Result := (Left_Real > Right_Real);
2946 when N_Op_Ge => Result := (Left_Real >= Right_Real);
2949 raise Program_Error;
2952 Fold_Uint (N, Test (Result), True);
2955 -- For all other cases, we use Compile_Time_Compare to do the compare
2959 CR : constant Compare_Result :=
2960 Compile_Time_Compare (Left, Right, Assume_Valid => False);
2963 if CR = Unknown then
2971 elsif CR = NE or else CR = GT or else CR = LT then
2978 if CR = NE or else CR = GT or else CR = LT then
2989 elsif CR = EQ or else CR = GT or else CR = GE then
2996 if CR = LT or else CR = EQ or else CR = LE then
3007 elsif CR = EQ or else CR = LT or else CR = LE then
3014 if CR = GT or else CR = EQ or else CR = GE then
3023 raise Program_Error;
3027 Fold_Uint (N, Test (Result), Stat);
3030 -- For the case of a folded relational operator on a specific numeric
3031 -- type, freeze operand type now.
3033 if Present (Otype) then
3034 Freeze_Before (N, Otype);
3037 Warn_On_Known_Condition (N);
3038 end Eval_Relational_Op;
3044 -- Shift operations are intrinsic operations that can never be static, so
3045 -- the only processing required is to perform the required check for a non
3046 -- static context for the two operands.
3048 -- Actually we could do some compile time evaluation here some time ???
3050 procedure Eval_Shift (N : Node_Id) is
3052 Check_Non_Static_Context (Left_Opnd (N));
3053 Check_Non_Static_Context (Right_Opnd (N));
3056 ------------------------
3057 -- Eval_Short_Circuit --
3058 ------------------------
3060 -- A short circuit operation is potentially static if both operands are
3061 -- potentially static (RM 4.9 (13)).
3063 procedure Eval_Short_Circuit (N : Node_Id) is
3064 Kind : constant Node_Kind := Nkind (N);
3065 Left : constant Node_Id := Left_Opnd (N);
3066 Right : constant Node_Id := Right_Opnd (N);
3069 Rstat : constant Boolean :=
3070 Is_Static_Expression (Left)
3072 Is_Static_Expression (Right);
3075 -- Short circuit operations are never static in Ada 83
3077 if Ada_Version = Ada_83 and then Comes_From_Source (N) then
3078 Check_Non_Static_Context (Left);
3079 Check_Non_Static_Context (Right);
3083 -- Now look at the operands, we can't quite use the normal call to
3084 -- Test_Expression_Is_Foldable here because short circuit operations
3085 -- are a special case, they can still be foldable, even if the right
3086 -- operand raises constraint error.
3088 -- If either operand is Any_Type, just propagate to result and do not
3089 -- try to fold, this prevents cascaded errors.
3091 if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
3092 Set_Etype (N, Any_Type);
3095 -- If left operand raises constraint error, then replace node N with
3096 -- the raise constraint error node, and we are obviously not foldable.
3097 -- Is_Static_Expression is set from the two operands in the normal way,
3098 -- and we check the right operand if it is in a non-static context.
3100 elsif Raises_Constraint_Error (Left) then
3102 Check_Non_Static_Context (Right);
3105 Rewrite_In_Raise_CE (N, Left);
3106 Set_Is_Static_Expression (N, Rstat);
3109 -- If the result is not static, then we won't in any case fold
3111 elsif not Rstat then
3112 Check_Non_Static_Context (Left);
3113 Check_Non_Static_Context (Right);
3117 -- Here the result is static, note that, unlike the normal processing
3118 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
3119 -- the right operand raises constraint error, that's because it is not
3120 -- significant if the left operand is decisive.
3122 Set_Is_Static_Expression (N);
3124 -- It does not matter if the right operand raises constraint error if
3125 -- it will not be evaluated. So deal specially with the cases where
3126 -- the right operand is not evaluated. Note that we will fold these
3127 -- cases even if the right operand is non-static, which is fine, but
3128 -- of course in these cases the result is not potentially static.
3130 Left_Int := Expr_Value (Left);
3132 if (Kind = N_And_Then and then Is_False (Left_Int))
3134 (Kind = N_Or_Else and then Is_True (Left_Int))
3136 Fold_Uint (N, Left_Int, Rstat);
3140 -- If first operand not decisive, then it does matter if the right
3141 -- operand raises constraint error, since it will be evaluated, so
3142 -- we simply replace the node with the right operand. Note that this
3143 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
3144 -- (both are set to True in Right).
3146 if Raises_Constraint_Error (Right) then
3147 Rewrite_In_Raise_CE (N, Right);
3148 Check_Non_Static_Context (Left);
3152 -- Otherwise the result depends on the right operand
3154 Fold_Uint (N, Expr_Value (Right), Rstat);
3156 end Eval_Short_Circuit;
3162 -- Slices can never be static, so the only processing required is to check
3163 -- for non-static context if an explicit range is given.
3165 procedure Eval_Slice (N : Node_Id) is
3166 Drange : constant Node_Id := Discrete_Range (N);
3168 if Nkind (Drange) = N_Range then
3169 Check_Non_Static_Context (Low_Bound (Drange));
3170 Check_Non_Static_Context (High_Bound (Drange));
3173 -- A slice of the form A (subtype), when the subtype is the index of
3174 -- the type of A, is redundant, the slice can be replaced with A, and
3175 -- this is worth a warning.
3177 if Is_Entity_Name (Prefix (N)) then
3179 E : constant Entity_Id := Entity (Prefix (N));
3180 T : constant Entity_Id := Etype (E);
3182 if Ekind (E) = E_Constant
3183 and then Is_Array_Type (T)
3184 and then Is_Entity_Name (Drange)
3186 if Is_Entity_Name (Original_Node (First_Index (T)))
3187 and then Entity (Original_Node (First_Index (T)))
3190 if Warn_On_Redundant_Constructs then
3191 Error_Msg_N ("redundant slice denotes whole array?", N);
3194 -- The following might be a useful optimization????
3196 -- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
3203 -------------------------
3204 -- Eval_String_Literal --
3205 -------------------------
3207 procedure Eval_String_Literal (N : Node_Id) is
3208 Typ : constant Entity_Id := Etype (N);
3209 Bas : constant Entity_Id := Base_Type (Typ);
3215 -- Nothing to do if error type (handles cases like default expressions
3216 -- or generics where we have not yet fully resolved the type).
3218 if Bas = Any_Type or else Bas = Any_String then
3222 -- String literals are static if the subtype is static (RM 4.9(2)), so
3223 -- reset the static expression flag (it was set unconditionally in
3224 -- Analyze_String_Literal) if the subtype is non-static. We tell if
3225 -- the subtype is static by looking at the lower bound.
3227 if Ekind (Typ) = E_String_Literal_Subtype then
3228 if not Is_OK_Static_Expression (String_Literal_Low_Bound (Typ)) then
3229 Set_Is_Static_Expression (N, False);
3233 -- Here if Etype of string literal is normal Etype (not yet possible,
3234 -- but may be possible in future).
3236 elsif not Is_OK_Static_Expression
3237 (Type_Low_Bound (Etype (First_Index (Typ))))
3239 Set_Is_Static_Expression (N, False);
3243 -- If original node was a type conversion, then result if non-static
3245 if Nkind (Original_Node (N)) = N_Type_Conversion then
3246 Set_Is_Static_Expression (N, False);
3250 -- Test for illegal Ada 95 cases. A string literal is illegal in Ada 95
3251 -- if its bounds are outside the index base type and this index type is
3252 -- static. This can happen in only two ways. Either the string literal
3253 -- is too long, or it is null, and the lower bound is type'First. In
3254 -- either case it is the upper bound that is out of range of the index
3257 if Ada_Version >= Ada_95 then
3258 if Root_Type (Bas) = Standard_String
3260 Root_Type (Bas) = Standard_Wide_String
3262 Xtp := Standard_Positive;
3264 Xtp := Etype (First_Index (Bas));
3267 if Ekind (Typ) = E_String_Literal_Subtype then
3268 Lo := String_Literal_Low_Bound (Typ);
3270 Lo := Type_Low_Bound (Etype (First_Index (Typ)));
3273 Len := String_Length (Strval (N));
3275 if UI_From_Int (Len) > String_Type_Len (Bas) then
3276 Apply_Compile_Time_Constraint_Error
3277 (N, "string literal too long for}", CE_Length_Check_Failed,
3279 Typ => First_Subtype (Bas));
3282 and then not Is_Generic_Type (Xtp)
3284 Expr_Value (Lo) = Expr_Value (Type_Low_Bound (Base_Type (Xtp)))
3286 Apply_Compile_Time_Constraint_Error
3287 (N, "null string literal not allowed for}",
3288 CE_Length_Check_Failed,
3290 Typ => First_Subtype (Bas));
3293 end Eval_String_Literal;
3295 --------------------------
3296 -- Eval_Type_Conversion --
3297 --------------------------
3299 -- A type conversion is potentially static if its subtype mark is for a
3300 -- static scalar subtype, and its operand expression is potentially static
3303 procedure Eval_Type_Conversion (N : Node_Id) is
3304 Operand : constant Node_Id := Expression (N);
3305 Source_Type : constant Entity_Id := Etype (Operand);
3306 Target_Type : constant Entity_Id := Etype (N);
3311 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean;
3312 -- Returns true if type T is an integer type, or if it is a fixed-point
3313 -- type to be treated as an integer (i.e. the flag Conversion_OK is set
3314 -- on the conversion node).
3316 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean;
3317 -- Returns true if type T is a floating-point type, or if it is a
3318 -- fixed-point type that is not to be treated as an integer (i.e. the
3319 -- flag Conversion_OK is not set on the conversion node).
3321 ------------------------------
3322 -- To_Be_Treated_As_Integer --
3323 ------------------------------
3325 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean is
3329 or else (Is_Fixed_Point_Type (T) and then Conversion_OK (N));
3330 end To_Be_Treated_As_Integer;
3332 ---------------------------
3333 -- To_Be_Treated_As_Real --
3334 ---------------------------
3336 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean is
3339 Is_Floating_Point_Type (T)
3340 or else (Is_Fixed_Point_Type (T) and then not Conversion_OK (N));
3341 end To_Be_Treated_As_Real;
3343 -- Start of processing for Eval_Type_Conversion
3346 -- Cannot fold if target type is non-static or if semantic error
3348 if not Is_Static_Subtype (Target_Type) then
3349 Check_Non_Static_Context (Operand);
3352 elsif Error_Posted (N) then
3356 -- If not foldable we are done
3358 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
3363 -- Don't try fold if target type has constraint error bounds
3365 elsif not Is_OK_Static_Subtype (Target_Type) then
3366 Set_Raises_Constraint_Error (N);
3370 -- Remaining processing depends on operand types. Note that in the
3371 -- following type test, fixed-point counts as real unless the flag
3372 -- Conversion_OK is set, in which case it counts as integer.
3374 -- Fold conversion, case of string type. The result is not static
3376 if Is_String_Type (Target_Type) then
3377 Fold_Str (N, Strval (Get_String_Val (Operand)), Static => False);
3381 -- Fold conversion, case of integer target type
3383 elsif To_Be_Treated_As_Integer (Target_Type) then
3388 -- Integer to integer conversion
3390 if To_Be_Treated_As_Integer (Source_Type) then
3391 Result := Expr_Value (Operand);
3393 -- Real to integer conversion
3396 Result := UR_To_Uint (Expr_Value_R (Operand));
3399 -- If fixed-point type (Conversion_OK must be set), then the
3400 -- result is logically an integer, but we must replace the
3401 -- conversion with the corresponding real literal, since the
3402 -- type from a semantic point of view is still fixed-point.
3404 if Is_Fixed_Point_Type (Target_Type) then
3406 (N, UR_From_Uint (Result) * Small_Value (Target_Type), Stat);
3408 -- Otherwise result is integer literal
3411 Fold_Uint (N, Result, Stat);
3415 -- Fold conversion, case of real target type
3417 elsif To_Be_Treated_As_Real (Target_Type) then
3422 if To_Be_Treated_As_Real (Source_Type) then
3423 Result := Expr_Value_R (Operand);
3425 Result := UR_From_Uint (Expr_Value (Operand));
3428 Fold_Ureal (N, Result, Stat);
3431 -- Enumeration types
3434 Fold_Uint (N, Expr_Value (Operand), Stat);
3437 if Is_Out_Of_Range (N, Etype (N), Assume_Valid => True) then
3441 end Eval_Type_Conversion;
3447 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
3448 -- are potentially static if the operand is potentially static (RM 4.9(7)).
3450 procedure Eval_Unary_Op (N : Node_Id) is
3451 Right : constant Node_Id := Right_Opnd (N);
3452 Otype : Entity_Id := Empty;
3457 -- If not foldable we are done
3459 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
3465 if Etype (Right) = Universal_Integer
3467 Etype (Right) = Universal_Real
3469 Otype := Find_Universal_Operator_Type (N);
3472 -- Fold for integer case
3474 if Is_Integer_Type (Etype (N)) then
3476 Rint : constant Uint := Expr_Value (Right);
3480 -- In the case of modular unary plus and abs there is no need
3481 -- to adjust the result of the operation since if the original
3482 -- operand was in bounds the result will be in the bounds of the
3483 -- modular type. However, in the case of modular unary minus the
3484 -- result may go out of the bounds of the modular type and needs
3487 if Nkind (N) = N_Op_Plus then
3490 elsif Nkind (N) = N_Op_Minus then
3491 if Is_Modular_Integer_Type (Etype (N)) then
3492 Result := (-Rint) mod Modulus (Etype (N));
3498 pragma Assert (Nkind (N) = N_Op_Abs);
3502 Fold_Uint (N, Result, Stat);
3505 -- Fold for real case
3507 elsif Is_Real_Type (Etype (N)) then
3509 Rreal : constant Ureal := Expr_Value_R (Right);
3513 if Nkind (N) = N_Op_Plus then
3516 elsif Nkind (N) = N_Op_Minus then
3517 Result := UR_Negate (Rreal);
3520 pragma Assert (Nkind (N) = N_Op_Abs);
3521 Result := abs Rreal;
3524 Fold_Ureal (N, Result, Stat);
3528 -- If the operator was resolved to a specific type, make sure that type
3529 -- is frozen even if the expression is folded into a literal (which has
3530 -- a universal type).
3532 if Present (Otype) then
3533 Freeze_Before (N, Otype);
3537 -------------------------------
3538 -- Eval_Unchecked_Conversion --
3539 -------------------------------
3541 -- Unchecked conversions can never be static, so the only required
3542 -- processing is to check for a non-static context for the operand.
3544 procedure Eval_Unchecked_Conversion (N : Node_Id) is
3546 Check_Non_Static_Context (Expression (N));
3547 end Eval_Unchecked_Conversion;
3549 --------------------
3550 -- Expr_Rep_Value --
3551 --------------------
3553 function Expr_Rep_Value (N : Node_Id) return Uint is
3554 Kind : constant Node_Kind := Nkind (N);
3558 if Is_Entity_Name (N) then
3561 -- An enumeration literal that was either in the source or created
3562 -- as a result of static evaluation.
3564 if Ekind (Ent) = E_Enumeration_Literal then
3565 return Enumeration_Rep (Ent);
3567 -- A user defined static constant
3570 pragma Assert (Ekind (Ent) = E_Constant);
3571 return Expr_Rep_Value (Constant_Value (Ent));
3574 -- An integer literal that was either in the source or created as a
3575 -- result of static evaluation.
3577 elsif Kind = N_Integer_Literal then
3580 -- A real literal for a fixed-point type. This must be the fixed-point
3581 -- case, either the literal is of a fixed-point type, or it is a bound
3582 -- of a fixed-point type, with type universal real. In either case we
3583 -- obtain the desired value from Corresponding_Integer_Value.
3585 elsif Kind = N_Real_Literal then
3586 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
3587 return Corresponding_Integer_Value (N);
3589 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3591 elsif Kind = N_Attribute_Reference
3592 and then Attribute_Name (N) = Name_Null_Parameter
3596 -- Otherwise must be character literal
3599 pragma Assert (Kind = N_Character_Literal);
3602 -- Since Character literals of type Standard.Character don't have any
3603 -- defining character literals built for them, they do not have their
3604 -- Entity set, so just use their Char code. Otherwise for user-
3605 -- defined character literals use their Pos value as usual which is
3606 -- the same as the Rep value.
3609 return Char_Literal_Value (N);
3611 return Enumeration_Rep (Ent);
3620 function Expr_Value (N : Node_Id) return Uint is
3621 Kind : constant Node_Kind := Nkind (N);
3622 CV_Ent : CV_Entry renames CV_Cache (Nat (N) mod CV_Cache_Size);
3627 -- If already in cache, then we know it's compile time known and we can
3628 -- return the value that was previously stored in the cache since
3629 -- compile time known values cannot change.
3631 if CV_Ent.N = N then
3635 -- Otherwise proceed to test value
3637 if Is_Entity_Name (N) then
3640 -- An enumeration literal that was either in the source or created as
3641 -- a result of static evaluation.
3643 if Ekind (Ent) = E_Enumeration_Literal then
3644 Val := Enumeration_Pos (Ent);
3646 -- A user defined static constant
3649 pragma Assert (Ekind (Ent) = E_Constant);
3650 Val := Expr_Value (Constant_Value (Ent));
3653 -- An integer literal that was either in the source or created as a
3654 -- result of static evaluation.
3656 elsif Kind = N_Integer_Literal then
3659 -- A real literal for a fixed-point type. This must be the fixed-point
3660 -- case, either the literal is of a fixed-point type, or it is a bound
3661 -- of a fixed-point type, with type universal real. In either case we
3662 -- obtain the desired value from Corresponding_Integer_Value.
3664 elsif Kind = N_Real_Literal then
3666 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
3667 Val := Corresponding_Integer_Value (N);
3669 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3671 elsif Kind = N_Attribute_Reference
3672 and then Attribute_Name (N) = Name_Null_Parameter
3676 -- Otherwise must be character literal
3679 pragma Assert (Kind = N_Character_Literal);
3682 -- Since Character literals of type Standard.Character don't
3683 -- have any defining character literals built for them, they
3684 -- do not have their Entity set, so just use their Char
3685 -- code. Otherwise for user-defined character literals use
3686 -- their Pos value as usual.
3689 Val := Char_Literal_Value (N);
3691 Val := Enumeration_Pos (Ent);
3695 -- Come here with Val set to value to be returned, set cache
3706 function Expr_Value_E (N : Node_Id) return Entity_Id is
3707 Ent : constant Entity_Id := Entity (N);
3710 if Ekind (Ent) = E_Enumeration_Literal then
3713 pragma Assert (Ekind (Ent) = E_Constant);
3714 return Expr_Value_E (Constant_Value (Ent));
3722 function Expr_Value_R (N : Node_Id) return Ureal is
3723 Kind : constant Node_Kind := Nkind (N);
3728 if Kind = N_Real_Literal then
3731 elsif Kind = N_Identifier or else Kind = N_Expanded_Name then
3733 pragma Assert (Ekind (Ent) = E_Constant);
3734 return Expr_Value_R (Constant_Value (Ent));
3736 elsif Kind = N_Integer_Literal then
3737 return UR_From_Uint (Expr_Value (N));
3739 -- Strange case of VAX literals, which are at this stage transformed
3740 -- into Vax_Type!x_To_y(IEEE_Literal). See Expand_N_Real_Literal in
3741 -- Exp_Vfpt for further details.
3743 elsif Vax_Float (Etype (N))
3744 and then Nkind (N) = N_Unchecked_Type_Conversion
3746 Expr := Expression (N);
3748 if Nkind (Expr) = N_Function_Call
3749 and then Present (Parameter_Associations (Expr))
3751 Expr := First (Parameter_Associations (Expr));
3753 if Nkind (Expr) = N_Real_Literal then
3754 return Realval (Expr);
3758 -- Peculiar VMS case, if we have xxx'Null_Parameter, return 0.0
3760 elsif Kind = N_Attribute_Reference
3761 and then Attribute_Name (N) = Name_Null_Parameter
3766 -- If we fall through, we have a node that cannot be interpreted as a
3767 -- compile time constant. That is definitely an error.
3769 raise Program_Error;
3776 function Expr_Value_S (N : Node_Id) return Node_Id is
3778 if Nkind (N) = N_String_Literal then
3781 pragma Assert (Ekind (Entity (N)) = E_Constant);
3782 return Expr_Value_S (Constant_Value (Entity (N)));
3786 ----------------------------------
3787 -- Find_Universal_Operator_Type --
3788 ----------------------------------
3790 function Find_Universal_Operator_Type (N : Node_Id) return Entity_Id is
3791 PN : constant Node_Id := Parent (N);
3792 Call : constant Node_Id := Original_Node (N);
3793 Is_Int : constant Boolean := Is_Integer_Type (Etype (N));
3795 Is_Fix : constant Boolean :=
3796 Nkind (N) in N_Binary_Op
3797 and then Nkind (Right_Opnd (N)) /= Nkind (Left_Opnd (N));
3798 -- A mixed-mode operation in this context indicates the presence of
3799 -- fixed-point type in the designated package.
3801 Is_Relational : constant Boolean := Etype (N) = Standard_Boolean;
3802 -- Case where N is a relational (or membership) operator (else it is an
3805 In_Membership : constant Boolean :=
3806 Nkind (PN) in N_Membership_Test
3808 Nkind (Right_Opnd (PN)) = N_Range
3810 Is_Universal_Numeric_Type (Etype (Left_Opnd (PN)))
3812 Is_Universal_Numeric_Type
3813 (Etype (Low_Bound (Right_Opnd (PN))))
3815 Is_Universal_Numeric_Type
3816 (Etype (High_Bound (Right_Opnd (PN))));
3817 -- Case where N is part of a membership test with a universal range
3821 Typ1 : Entity_Id := Empty;
3824 function Is_Mixed_Mode_Operand (Op : Node_Id) return Boolean;
3825 -- Check whether one operand is a mixed-mode operation that requires the
3826 -- presence of a fixed-point type. Given that all operands are universal
3827 -- and have been constant-folded, retrieve the original function call.
3829 ---------------------------
3830 -- Is_Mixed_Mode_Operand --
3831 ---------------------------
3833 function Is_Mixed_Mode_Operand (Op : Node_Id) return Boolean is
3834 Onod : constant Node_Id := Original_Node (Op);
3836 return Nkind (Onod) = N_Function_Call
3837 and then Present (Next_Actual (First_Actual (Onod)))
3838 and then Etype (First_Actual (Onod)) /=
3839 Etype (Next_Actual (First_Actual (Onod)));
3840 end Is_Mixed_Mode_Operand;
3842 -- Start of processing for Find_Universal_Operator_Type
3845 if Nkind (Call) /= N_Function_Call
3846 or else Nkind (Name (Call)) /= N_Expanded_Name
3850 -- There are several cases where the context does not imply the type of
3852 -- - the universal expression appears in a type conversion;
3853 -- - the expression is a relational operator applied to universal
3855 -- - the expression is a membership test with a universal operand
3856 -- and a range with universal bounds.
3858 elsif Nkind (Parent (N)) = N_Type_Conversion
3859 or else Is_Relational
3860 or else In_Membership
3862 Pack := Entity (Prefix (Name (Call)));
3864 -- If the prefix is a package declared elsewhere, iterate over its
3865 -- visible entities, otherwise iterate over all declarations in the
3866 -- designated scope.
3868 if Ekind (Pack) = E_Package
3869 and then not In_Open_Scopes (Pack)
3871 Priv_E := First_Private_Entity (Pack);
3877 E := First_Entity (Pack);
3878 while Present (E) and then E /= Priv_E loop
3879 if Is_Numeric_Type (E)
3880 and then Nkind (Parent (E)) /= N_Subtype_Declaration
3881 and then Comes_From_Source (E)
3882 and then Is_Integer_Type (E) = Is_Int
3884 (Nkind (N) in N_Unary_Op
3885 or else Is_Relational
3886 or else Is_Fixed_Point_Type (E) = Is_Fix)
3891 -- Before emitting an error, check for the presence of a
3892 -- mixed-mode operation that specifies a fixed point type.
3896 (Is_Mixed_Mode_Operand (Left_Opnd (N))
3897 or else Is_Mixed_Mode_Operand (Right_Opnd (N)))
3898 and then Is_Fixed_Point_Type (E) /= Is_Fixed_Point_Type (Typ1)
3901 if Is_Fixed_Point_Type (E) then
3906 -- More than one type of the proper class declared in P
3908 Error_Msg_N ("ambiguous operation", N);
3909 Error_Msg_Sloc := Sloc (Typ1);
3910 Error_Msg_N ("\possible interpretation (inherited)#", N);
3911 Error_Msg_Sloc := Sloc (E);
3912 Error_Msg_N ("\possible interpretation (inherited)#", N);
3922 end Find_Universal_Operator_Type;
3924 --------------------------
3925 -- Flag_Non_Static_Expr --
3926 --------------------------
3928 procedure Flag_Non_Static_Expr (Msg : String; Expr : Node_Id) is
3930 if Error_Posted (Expr) and then not All_Errors_Mode then
3933 Error_Msg_F (Msg, Expr);
3934 Why_Not_Static (Expr);
3936 end Flag_Non_Static_Expr;
3942 procedure Fold_Str (N : Node_Id; Val : String_Id; Static : Boolean) is
3943 Loc : constant Source_Ptr := Sloc (N);
3944 Typ : constant Entity_Id := Etype (N);
3947 Rewrite (N, Make_String_Literal (Loc, Strval => Val));
3949 -- We now have the literal with the right value, both the actual type
3950 -- and the expected type of this literal are taken from the expression
3951 -- that was evaluated.
3954 Set_Is_Static_Expression (N, Static);
3963 procedure Fold_Uint (N : Node_Id; Val : Uint; Static : Boolean) is
3964 Loc : constant Source_Ptr := Sloc (N);
3965 Typ : Entity_Id := Etype (N);
3969 -- If we are folding a named number, retain the entity in the literal,
3972 if Is_Entity_Name (N)
3973 and then Ekind (Entity (N)) = E_Named_Integer
3980 if Is_Private_Type (Typ) then
3981 Typ := Full_View (Typ);
3984 -- For a result of type integer, substitute an N_Integer_Literal node
3985 -- for the result of the compile time evaluation of the expression.
3986 -- For ASIS use, set a link to the original named number when not in
3987 -- a generic context.
3989 if Is_Integer_Type (Typ) then
3990 Rewrite (N, Make_Integer_Literal (Loc, Val));
3992 Set_Original_Entity (N, Ent);
3994 -- Otherwise we have an enumeration type, and we substitute either
3995 -- an N_Identifier or N_Character_Literal to represent the enumeration
3996 -- literal corresponding to the given value, which must always be in
3997 -- range, because appropriate tests have already been made for this.
3999 else pragma Assert (Is_Enumeration_Type (Typ));
4000 Rewrite (N, Get_Enum_Lit_From_Pos (Etype (N), Val, Loc));
4003 -- We now have the literal with the right value, both the actual type
4004 -- and the expected type of this literal are taken from the expression
4005 -- that was evaluated.
4008 Set_Is_Static_Expression (N, Static);
4017 procedure Fold_Ureal (N : Node_Id; Val : Ureal; Static : Boolean) is
4018 Loc : constant Source_Ptr := Sloc (N);
4019 Typ : constant Entity_Id := Etype (N);
4023 -- If we are folding a named number, retain the entity in the literal,
4026 if Is_Entity_Name (N)
4027 and then Ekind (Entity (N)) = E_Named_Real
4034 Rewrite (N, Make_Real_Literal (Loc, Realval => Val));
4036 -- Set link to original named number, for ASIS use
4038 Set_Original_Entity (N, Ent);
4040 -- Both the actual and expected type comes from the original expression
4043 Set_Is_Static_Expression (N, Static);
4052 function From_Bits (B : Bits; T : Entity_Id) return Uint is
4056 for J in 0 .. B'Last loop
4062 if Non_Binary_Modulus (T) then
4063 V := V mod Modulus (T);
4069 --------------------
4070 -- Get_String_Val --
4071 --------------------
4073 function Get_String_Val (N : Node_Id) return Node_Id is
4075 if Nkind (N) = N_String_Literal then
4078 elsif Nkind (N) = N_Character_Literal then
4082 pragma Assert (Is_Entity_Name (N));
4083 return Get_String_Val (Constant_Value (Entity (N)));
4091 procedure Initialize is
4093 CV_Cache := (others => (Node_High_Bound, Uint_0));
4096 --------------------
4097 -- In_Subrange_Of --
4098 --------------------
4100 function In_Subrange_Of
4103 Fixed_Int : Boolean := False) return Boolean
4112 if T1 = T2 or else Is_Subtype_Of (T1, T2) then
4115 -- Never in range if both types are not scalar. Don't know if this can
4116 -- actually happen, but just in case.
4118 elsif not Is_Scalar_Type (T1) or else not Is_Scalar_Type (T1) then
4121 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
4122 -- definitely not compatible with T2.
4124 elsif Is_Floating_Point_Type (T1)
4125 and then Has_Infinities (T1)
4126 and then Is_Floating_Point_Type (T2)
4127 and then not Has_Infinities (T2)
4132 L1 := Type_Low_Bound (T1);
4133 H1 := Type_High_Bound (T1);
4135 L2 := Type_Low_Bound (T2);
4136 H2 := Type_High_Bound (T2);
4138 -- Check bounds to see if comparison possible at compile time
4140 if Compile_Time_Compare (L1, L2, Assume_Valid => True) in Compare_GE
4142 Compile_Time_Compare (H1, H2, Assume_Valid => True) in Compare_LE
4147 -- If bounds not comparable at compile time, then the bounds of T2
4148 -- must be compile time known or we cannot answer the query.
4150 if not Compile_Time_Known_Value (L2)
4151 or else not Compile_Time_Known_Value (H2)
4156 -- If the bounds of T1 are know at compile time then use these
4157 -- ones, otherwise use the bounds of the base type (which are of
4158 -- course always static).
4160 if not Compile_Time_Known_Value (L1) then
4161 L1 := Type_Low_Bound (Base_Type (T1));
4164 if not Compile_Time_Known_Value (H1) then
4165 H1 := Type_High_Bound (Base_Type (T1));
4168 -- Fixed point types should be considered as such only if
4169 -- flag Fixed_Int is set to False.
4171 if Is_Floating_Point_Type (T1) or else Is_Floating_Point_Type (T2)
4172 or else (Is_Fixed_Point_Type (T1) and then not Fixed_Int)
4173 or else (Is_Fixed_Point_Type (T2) and then not Fixed_Int)
4176 Expr_Value_R (L2) <= Expr_Value_R (L1)
4178 Expr_Value_R (H2) >= Expr_Value_R (H1);
4182 Expr_Value (L2) <= Expr_Value (L1)
4184 Expr_Value (H2) >= Expr_Value (H1);
4189 -- If any exception occurs, it means that we have some bug in the compiler
4190 -- possibly triggered by a previous error, or by some unforeseen peculiar
4191 -- occurrence. However, this is only an optimization attempt, so there is
4192 -- really no point in crashing the compiler. Instead we just decide, too
4193 -- bad, we can't figure out the answer in this case after all.
4198 -- Debug flag K disables this behavior (useful for debugging)
4200 if Debug_Flag_K then
4211 function Is_In_Range
4214 Assume_Valid : Boolean := False;
4215 Fixed_Int : Boolean := False;
4216 Int_Real : Boolean := False) return Boolean
4219 return Test_In_Range (N, Typ, Assume_Valid, Fixed_Int, Int_Real)
4227 function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
4228 Typ : constant Entity_Id := Etype (Lo);
4231 if not Compile_Time_Known_Value (Lo)
4232 or else not Compile_Time_Known_Value (Hi)
4237 if Is_Discrete_Type (Typ) then
4238 return Expr_Value (Lo) > Expr_Value (Hi);
4241 pragma Assert (Is_Real_Type (Typ));
4242 return Expr_Value_R (Lo) > Expr_Value_R (Hi);
4246 -----------------------------
4247 -- Is_OK_Static_Expression --
4248 -----------------------------
4250 function Is_OK_Static_Expression (N : Node_Id) return Boolean is
4252 return Is_Static_Expression (N)
4253 and then not Raises_Constraint_Error (N);
4254 end Is_OK_Static_Expression;
4256 ------------------------
4257 -- Is_OK_Static_Range --
4258 ------------------------
4260 -- A static range is a range whose bounds are static expressions, or a
4261 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4262 -- We have already converted range attribute references, so we get the
4263 -- "or" part of this rule without needing a special test.
4265 function Is_OK_Static_Range (N : Node_Id) return Boolean is
4267 return Is_OK_Static_Expression (Low_Bound (N))
4268 and then Is_OK_Static_Expression (High_Bound (N));
4269 end Is_OK_Static_Range;
4271 --------------------------
4272 -- Is_OK_Static_Subtype --
4273 --------------------------
4275 -- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
4276 -- neither bound raises constraint error when evaluated.
4278 function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean is
4279 Base_T : constant Entity_Id := Base_Type (Typ);
4280 Anc_Subt : Entity_Id;
4283 -- First a quick check on the non static subtype flag. As described
4284 -- in further detail in Einfo, this flag is not decisive in all cases,
4285 -- but if it is set, then the subtype is definitely non-static.
4287 if Is_Non_Static_Subtype (Typ) then
4291 Anc_Subt := Ancestor_Subtype (Typ);
4293 if Anc_Subt = Empty then
4297 if Is_Generic_Type (Root_Type (Base_T))
4298 or else Is_Generic_Actual_Type (Base_T)
4304 elsif Is_String_Type (Typ) then
4306 Ekind (Typ) = E_String_Literal_Subtype
4308 (Is_OK_Static_Subtype (Component_Type (Typ))
4309 and then Is_OK_Static_Subtype (Etype (First_Index (Typ))));
4313 elsif Is_Scalar_Type (Typ) then
4314 if Base_T = Typ then
4318 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
4319 -- Get_Type_{Low,High}_Bound.
4321 return Is_OK_Static_Subtype (Anc_Subt)
4322 and then Is_OK_Static_Expression (Type_Low_Bound (Typ))
4323 and then Is_OK_Static_Expression (Type_High_Bound (Typ));
4326 -- Types other than string and scalar types are never static
4331 end Is_OK_Static_Subtype;
4333 ---------------------
4334 -- Is_Out_Of_Range --
4335 ---------------------
4337 function Is_Out_Of_Range
4340 Assume_Valid : Boolean := False;
4341 Fixed_Int : Boolean := False;
4342 Int_Real : Boolean := False) return Boolean
4345 return Test_In_Range (N, Typ, Assume_Valid, Fixed_Int, Int_Real)
4347 end Is_Out_Of_Range;
4349 ---------------------
4350 -- Is_Static_Range --
4351 ---------------------
4353 -- A static range is a range whose bounds are static expressions, or a
4354 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4355 -- We have already converted range attribute references, so we get the
4356 -- "or" part of this rule without needing a special test.
4358 function Is_Static_Range (N : Node_Id) return Boolean is
4360 return Is_Static_Expression (Low_Bound (N))
4361 and then Is_Static_Expression (High_Bound (N));
4362 end Is_Static_Range;
4364 -----------------------
4365 -- Is_Static_Subtype --
4366 -----------------------
4368 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
4370 function Is_Static_Subtype (Typ : Entity_Id) return Boolean is
4371 Base_T : constant Entity_Id := Base_Type (Typ);
4372 Anc_Subt : Entity_Id;
4375 -- First a quick check on the non static subtype flag. As described
4376 -- in further detail in Einfo, this flag is not decisive in all cases,
4377 -- but if it is set, then the subtype is definitely non-static.
4379 if Is_Non_Static_Subtype (Typ) then
4383 Anc_Subt := Ancestor_Subtype (Typ);
4385 if Anc_Subt = Empty then
4389 if Is_Generic_Type (Root_Type (Base_T))
4390 or else Is_Generic_Actual_Type (Base_T)
4396 elsif Is_String_Type (Typ) then
4398 Ekind (Typ) = E_String_Literal_Subtype
4400 (Is_Static_Subtype (Component_Type (Typ))
4401 and then Is_Static_Subtype (Etype (First_Index (Typ))));
4405 elsif Is_Scalar_Type (Typ) then
4406 if Base_T = Typ then
4410 return Is_Static_Subtype (Anc_Subt)
4411 and then Is_Static_Expression (Type_Low_Bound (Typ))
4412 and then Is_Static_Expression (Type_High_Bound (Typ));
4415 -- Types other than string and scalar types are never static
4420 end Is_Static_Subtype;
4422 --------------------
4423 -- Not_Null_Range --
4424 --------------------
4426 function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
4427 Typ : constant Entity_Id := Etype (Lo);
4430 if not Compile_Time_Known_Value (Lo)
4431 or else not Compile_Time_Known_Value (Hi)
4436 if Is_Discrete_Type (Typ) then
4437 return Expr_Value (Lo) <= Expr_Value (Hi);
4440 pragma Assert (Is_Real_Type (Typ));
4442 return Expr_Value_R (Lo) <= Expr_Value_R (Hi);
4450 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean is
4452 -- We allow a maximum of 500,000 bits which seems a reasonable limit
4454 if Bits < 500_000 then
4458 Error_Msg_N ("static value too large, capacity exceeded", N);
4467 procedure Out_Of_Range (N : Node_Id) is
4469 -- If we have the static expression case, then this is an illegality
4470 -- in Ada 95 mode, except that in an instance, we never generate an
4471 -- error (if the error is legitimate, it was already diagnosed in the
4472 -- template). The expression to compute the length of a packed array is
4473 -- attached to the array type itself, and deserves a separate message.
4475 if Is_Static_Expression (N)
4476 and then not In_Instance
4477 and then not In_Inlined_Body
4478 and then Ada_Version >= Ada_95
4480 if Nkind (Parent (N)) = N_Defining_Identifier
4481 and then Is_Array_Type (Parent (N))
4482 and then Present (Packed_Array_Type (Parent (N)))
4483 and then Present (First_Rep_Item (Parent (N)))
4486 ("length of packed array must not exceed Integer''Last",
4487 First_Rep_Item (Parent (N)));
4488 Rewrite (N, Make_Integer_Literal (Sloc (N), Uint_1));
4491 Apply_Compile_Time_Constraint_Error
4492 (N, "value not in range of}", CE_Range_Check_Failed);
4495 -- Here we generate a warning for the Ada 83 case, or when we are in an
4496 -- instance, or when we have a non-static expression case.
4499 Apply_Compile_Time_Constraint_Error
4500 (N, "value not in range of}?", CE_Range_Check_Failed);
4504 -------------------------
4505 -- Rewrite_In_Raise_CE --
4506 -------------------------
4508 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id) is
4509 Typ : constant Entity_Id := Etype (N);
4512 -- If we want to raise CE in the condition of a N_Raise_CE node
4513 -- we may as well get rid of the condition.
4515 if Present (Parent (N))
4516 and then Nkind (Parent (N)) = N_Raise_Constraint_Error
4518 Set_Condition (Parent (N), Empty);
4520 -- If the expression raising CE is a N_Raise_CE node, we can use that
4521 -- one. We just preserve the type of the context.
4523 elsif Nkind (Exp) = N_Raise_Constraint_Error then
4527 -- Else build an explcit N_Raise_CE
4531 Make_Raise_Constraint_Error (Sloc (Exp),
4532 Reason => CE_Range_Check_Failed));
4533 Set_Raises_Constraint_Error (N);
4536 end Rewrite_In_Raise_CE;
4538 ---------------------
4539 -- String_Type_Len --
4540 ---------------------
4542 function String_Type_Len (Stype : Entity_Id) return Uint is
4543 NT : constant Entity_Id := Etype (First_Index (Stype));
4547 if Is_OK_Static_Subtype (NT) then
4550 T := Base_Type (NT);
4553 return Expr_Value (Type_High_Bound (T)) -
4554 Expr_Value (Type_Low_Bound (T)) + 1;
4555 end String_Type_Len;
4557 ------------------------------------
4558 -- Subtypes_Statically_Compatible --
4559 ------------------------------------
4561 function Subtypes_Statically_Compatible
4563 T2 : Entity_Id) return Boolean
4568 if Is_Scalar_Type (T1) then
4570 -- Definitely compatible if we match
4572 if Subtypes_Statically_Match (T1, T2) then
4575 -- If either subtype is nonstatic then they're not compatible
4577 elsif not Is_Static_Subtype (T1)
4578 or else not Is_Static_Subtype (T2)
4582 -- If either type has constraint error bounds, then consider that
4583 -- they match to avoid junk cascaded errors here.
4585 elsif not Is_OK_Static_Subtype (T1)
4586 or else not Is_OK_Static_Subtype (T2)
4590 -- Base types must match, but we don't check that (should we???) but
4591 -- we do at least check that both types are real, or both types are
4594 elsif Is_Real_Type (T1) /= Is_Real_Type (T2) then
4597 -- Here we check the bounds
4601 LB1 : constant Node_Id := Type_Low_Bound (T1);
4602 HB1 : constant Node_Id := Type_High_Bound (T1);
4603 LB2 : constant Node_Id := Type_Low_Bound (T2);
4604 HB2 : constant Node_Id := Type_High_Bound (T2);
4607 if Is_Real_Type (T1) then
4609 (Expr_Value_R (LB1) > Expr_Value_R (HB1))
4611 (Expr_Value_R (LB2) <= Expr_Value_R (LB1)
4613 Expr_Value_R (HB1) <= Expr_Value_R (HB2));
4617 (Expr_Value (LB1) > Expr_Value (HB1))
4619 (Expr_Value (LB2) <= Expr_Value (LB1)
4621 Expr_Value (HB1) <= Expr_Value (HB2));
4628 elsif Is_Access_Type (T1) then
4629 return (not Is_Constrained (T2)
4630 or else (Subtypes_Statically_Match
4631 (Designated_Type (T1), Designated_Type (T2))))
4632 and then not (Can_Never_Be_Null (T2)
4633 and then not Can_Never_Be_Null (T1));
4638 return (Is_Composite_Type (T1) and then not Is_Constrained (T2))
4639 or else Subtypes_Statically_Match (T1, T2);
4641 end Subtypes_Statically_Compatible;
4643 -------------------------------
4644 -- Subtypes_Statically_Match --
4645 -------------------------------
4647 -- Subtypes statically match if they have statically matching constraints
4648 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
4649 -- they are the same identical constraint, or if they are static and the
4650 -- values match (RM 4.9.1(1)).
4652 function Subtypes_Statically_Match (T1, T2 : Entity_Id) return Boolean is
4654 -- A type always statically matches itself
4661 elsif Is_Scalar_Type (T1) then
4663 -- Base types must be the same
4665 if Base_Type (T1) /= Base_Type (T2) then
4669 -- A constrained numeric subtype never matches an unconstrained
4670 -- subtype, i.e. both types must be constrained or unconstrained.
4672 -- To understand the requirement for this test, see RM 4.9.1(1).
4673 -- As is made clear in RM 3.5.4(11), type Integer, for example is
4674 -- a constrained subtype with constraint bounds matching the bounds
4675 -- of its corresponding unconstrained base type. In this situation,
4676 -- Integer and Integer'Base do not statically match, even though
4677 -- they have the same bounds.
4679 -- We only apply this test to types in Standard and types that appear
4680 -- in user programs. That way, we do not have to be too careful about
4681 -- setting Is_Constrained right for Itypes.
4683 if Is_Numeric_Type (T1)
4684 and then (Is_Constrained (T1) /= Is_Constrained (T2))
4685 and then (Scope (T1) = Standard_Standard
4686 or else Comes_From_Source (T1))
4687 and then (Scope (T2) = Standard_Standard
4688 or else Comes_From_Source (T2))
4692 -- A generic scalar type does not statically match its base type
4693 -- (AI-311). In this case we make sure that the formals, which are
4694 -- first subtypes of their bases, are constrained.
4696 elsif Is_Generic_Type (T1)
4697 and then Is_Generic_Type (T2)
4698 and then (Is_Constrained (T1) /= Is_Constrained (T2))
4703 -- If there was an error in either range, then just assume the types
4704 -- statically match to avoid further junk errors.
4706 if No (Scalar_Range (T1)) or else No (Scalar_Range (T2))
4707 or else Error_Posted (Scalar_Range (T1))
4708 or else Error_Posted (Scalar_Range (T2))
4713 -- Otherwise both types have bound that can be compared
4716 LB1 : constant Node_Id := Type_Low_Bound (T1);
4717 HB1 : constant Node_Id := Type_High_Bound (T1);
4718 LB2 : constant Node_Id := Type_Low_Bound (T2);
4719 HB2 : constant Node_Id := Type_High_Bound (T2);
4722 -- If the bounds are the same tree node, then match
4724 if LB1 = LB2 and then HB1 = HB2 then
4727 -- Otherwise bounds must be static and identical value
4730 if not Is_Static_Subtype (T1)
4731 or else not Is_Static_Subtype (T2)
4735 -- If either type has constraint error bounds, then say that
4736 -- they match to avoid junk cascaded errors here.
4738 elsif not Is_OK_Static_Subtype (T1)
4739 or else not Is_OK_Static_Subtype (T2)
4743 elsif Is_Real_Type (T1) then
4745 (Expr_Value_R (LB1) = Expr_Value_R (LB2))
4747 (Expr_Value_R (HB1) = Expr_Value_R (HB2));
4751 Expr_Value (LB1) = Expr_Value (LB2)
4753 Expr_Value (HB1) = Expr_Value (HB2);
4758 -- Type with discriminants
4760 elsif Has_Discriminants (T1) or else Has_Discriminants (T2) then
4762 -- Because of view exchanges in multiple instantiations, conformance
4763 -- checking might try to match a partial view of a type with no
4764 -- discriminants with a full view that has defaulted discriminants.
4765 -- In such a case, use the discriminant constraint of the full view,
4766 -- which must exist because we know that the two subtypes have the
4769 if Has_Discriminants (T1) /= Has_Discriminants (T2) then
4771 if Is_Private_Type (T2)
4772 and then Present (Full_View (T2))
4773 and then Has_Discriminants (Full_View (T2))
4775 return Subtypes_Statically_Match (T1, Full_View (T2));
4777 elsif Is_Private_Type (T1)
4778 and then Present (Full_View (T1))
4779 and then Has_Discriminants (Full_View (T1))
4781 return Subtypes_Statically_Match (Full_View (T1), T2);
4792 DL1 : constant Elist_Id := Discriminant_Constraint (T1);
4793 DL2 : constant Elist_Id := Discriminant_Constraint (T2);
4801 elsif Is_Constrained (T1) /= Is_Constrained (T2) then
4805 -- Now loop through the discriminant constraints
4807 -- Note: the guard here seems necessary, since it is possible at
4808 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
4810 if Present (DL1) and then Present (DL2) then
4811 DA1 := First_Elmt (DL1);
4812 DA2 := First_Elmt (DL2);
4813 while Present (DA1) loop
4815 Expr1 : constant Node_Id := Node (DA1);
4816 Expr2 : constant Node_Id := Node (DA2);
4819 if not Is_Static_Expression (Expr1)
4820 or else not Is_Static_Expression (Expr2)
4824 -- If either expression raised a constraint error,
4825 -- consider the expressions as matching, since this
4826 -- helps to prevent cascading errors.
4828 elsif Raises_Constraint_Error (Expr1)
4829 or else Raises_Constraint_Error (Expr2)
4833 elsif Expr_Value (Expr1) /= Expr_Value (Expr2) then
4846 -- A definite type does not match an indefinite or classwide type.
4847 -- However, a generic type with unknown discriminants may be
4848 -- instantiated with a type with no discriminants, and conformance
4849 -- checking on an inherited operation may compare the actual with the
4850 -- subtype that renames it in the instance.
4853 Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
4856 Is_Generic_Actual_Type (T1) or else Is_Generic_Actual_Type (T2);
4860 elsif Is_Array_Type (T1) then
4862 -- If either subtype is unconstrained then both must be, and if both
4863 -- are unconstrained then no further checking is needed.
4865 if not Is_Constrained (T1) or else not Is_Constrained (T2) then
4866 return not (Is_Constrained (T1) or else Is_Constrained (T2));
4869 -- Both subtypes are constrained, so check that the index subtypes
4870 -- statically match.
4873 Index1 : Node_Id := First_Index (T1);
4874 Index2 : Node_Id := First_Index (T2);
4877 while Present (Index1) loop
4879 Subtypes_Statically_Match (Etype (Index1), Etype (Index2))
4884 Next_Index (Index1);
4885 Next_Index (Index2);
4891 elsif Is_Access_Type (T1) then
4892 if Can_Never_Be_Null (T1) /= Can_Never_Be_Null (T2) then
4895 elsif Ekind_In (T1, E_Access_Subprogram_Type,
4896 E_Anonymous_Access_Subprogram_Type)
4900 (Designated_Type (T1),
4901 Designated_Type (T2));
4904 Subtypes_Statically_Match
4905 (Designated_Type (T1),
4906 Designated_Type (T2))
4907 and then Is_Access_Constant (T1) = Is_Access_Constant (T2);
4910 -- All other types definitely match
4915 end Subtypes_Statically_Match;
4921 function Test (Cond : Boolean) return Uint is
4930 ---------------------------------
4931 -- Test_Expression_Is_Foldable --
4932 ---------------------------------
4936 procedure Test_Expression_Is_Foldable
4946 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
4950 -- If operand is Any_Type, just propagate to result and do not
4951 -- try to fold, this prevents cascaded errors.
4953 if Etype (Op1) = Any_Type then
4954 Set_Etype (N, Any_Type);
4957 -- If operand raises constraint error, then replace node N with the
4958 -- raise constraint error node, and we are obviously not foldable.
4959 -- Note that this replacement inherits the Is_Static_Expression flag
4960 -- from the operand.
4962 elsif Raises_Constraint_Error (Op1) then
4963 Rewrite_In_Raise_CE (N, Op1);
4966 -- If the operand is not static, then the result is not static, and
4967 -- all we have to do is to check the operand since it is now known
4968 -- to appear in a non-static context.
4970 elsif not Is_Static_Expression (Op1) then
4971 Check_Non_Static_Context (Op1);
4972 Fold := Compile_Time_Known_Value (Op1);
4975 -- An expression of a formal modular type is not foldable because
4976 -- the modulus is unknown.
4978 elsif Is_Modular_Integer_Type (Etype (Op1))
4979 and then Is_Generic_Type (Etype (Op1))
4981 Check_Non_Static_Context (Op1);
4984 -- Here we have the case of an operand whose type is OK, which is
4985 -- static, and which does not raise constraint error, we can fold.
4988 Set_Is_Static_Expression (N);
4992 end Test_Expression_Is_Foldable;
4996 procedure Test_Expression_Is_Foldable
5003 Rstat : constant Boolean := Is_Static_Expression (Op1)
5004 and then Is_Static_Expression (Op2);
5010 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
5014 -- If either operand is Any_Type, just propagate to result and
5015 -- do not try to fold, this prevents cascaded errors.
5017 if Etype (Op1) = Any_Type or else Etype (Op2) = Any_Type then
5018 Set_Etype (N, Any_Type);
5021 -- If left operand raises constraint error, then replace node N with the
5022 -- Raise_Constraint_Error node, and we are obviously not foldable.
5023 -- Is_Static_Expression is set from the two operands in the normal way,
5024 -- and we check the right operand if it is in a non-static context.
5026 elsif Raises_Constraint_Error (Op1) then
5028 Check_Non_Static_Context (Op2);
5031 Rewrite_In_Raise_CE (N, Op1);
5032 Set_Is_Static_Expression (N, Rstat);
5035 -- Similar processing for the case of the right operand. Note that we
5036 -- don't use this routine for the short-circuit case, so we do not have
5037 -- to worry about that special case here.
5039 elsif Raises_Constraint_Error (Op2) then
5041 Check_Non_Static_Context (Op1);
5044 Rewrite_In_Raise_CE (N, Op2);
5045 Set_Is_Static_Expression (N, Rstat);
5048 -- Exclude expressions of a generic modular type, as above
5050 elsif Is_Modular_Integer_Type (Etype (Op1))
5051 and then Is_Generic_Type (Etype (Op1))
5053 Check_Non_Static_Context (Op1);
5056 -- If result is not static, then check non-static contexts on operands
5057 -- since one of them may be static and the other one may not be static.
5059 elsif not Rstat then
5060 Check_Non_Static_Context (Op1);
5061 Check_Non_Static_Context (Op2);
5062 Fold := Compile_Time_Known_Value (Op1)
5063 and then Compile_Time_Known_Value (Op2);
5066 -- Else result is static and foldable. Both operands are static, and
5067 -- neither raises constraint error, so we can definitely fold.
5070 Set_Is_Static_Expression (N);
5075 end Test_Expression_Is_Foldable;
5081 function Test_In_Range
5084 Assume_Valid : Boolean;
5085 Fixed_Int : Boolean;
5086 Int_Real : Boolean) return Range_Membership
5091 pragma Warnings (Off, Assume_Valid);
5092 -- For now Assume_Valid is unreferenced since the current implementation
5093 -- always returns Unknown if N is not a compile time known value, but we
5094 -- keep the parameter to allow for future enhancements in which we try
5095 -- to get the information in the variable case as well.
5098 -- Universal types have no range limits, so always in range
5100 if Typ = Universal_Integer or else Typ = Universal_Real then
5103 -- Never known if not scalar type. Don't know if this can actually
5104 -- happen, but our spec allows it, so we must check!
5106 elsif not Is_Scalar_Type (Typ) then
5109 -- Never known if this is a generic type, since the bounds of generic
5110 -- types are junk. Note that if we only checked for static expressions
5111 -- (instead of compile time known values) below, we would not need this
5112 -- check, because values of a generic type can never be static, but they
5113 -- can be known at compile time.
5115 elsif Is_Generic_Type (Typ) then
5118 -- Never known unless we have a compile time known value
5120 elsif not Compile_Time_Known_Value (N) then
5123 -- General processing with a known compile time value
5134 Lo := Type_Low_Bound (Typ);
5135 Hi := Type_High_Bound (Typ);
5137 LB_Known := Compile_Time_Known_Value (Lo);
5138 HB_Known := Compile_Time_Known_Value (Hi);
5140 -- Fixed point types should be considered as such only if flag
5141 -- Fixed_Int is set to False.
5143 if Is_Floating_Point_Type (Typ)
5144 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
5147 Valr := Expr_Value_R (N);
5149 if LB_Known and HB_Known then
5150 if Valr >= Expr_Value_R (Lo)
5152 Valr <= Expr_Value_R (Hi)
5156 return Out_Of_Range;
5159 elsif (LB_Known and then Valr < Expr_Value_R (Lo))
5161 (HB_Known and then Valr > Expr_Value_R (Hi))
5163 return Out_Of_Range;
5170 Val := Expr_Value (N);
5172 if LB_Known and HB_Known then
5173 if Val >= Expr_Value (Lo)
5175 Val <= Expr_Value (Hi)
5179 return Out_Of_Range;
5182 elsif (LB_Known and then Val < Expr_Value (Lo))
5184 (HB_Known and then Val > Expr_Value (Hi))
5186 return Out_Of_Range;
5200 procedure To_Bits (U : Uint; B : out Bits) is
5202 for J in 0 .. B'Last loop
5203 B (J) := (U / (2 ** J)) mod 2 /= 0;
5207 --------------------
5208 -- Why_Not_Static --
5209 --------------------
5211 procedure Why_Not_Static (Expr : Node_Id) is
5212 N : constant Node_Id := Original_Node (Expr);
5216 procedure Why_Not_Static_List (L : List_Id);
5217 -- A version that can be called on a list of expressions. Finds all
5218 -- non-static violations in any element of the list.
5220 -------------------------
5221 -- Why_Not_Static_List --
5222 -------------------------
5224 procedure Why_Not_Static_List (L : List_Id) is
5228 if Is_Non_Empty_List (L) then
5230 while Present (N) loop
5235 end Why_Not_Static_List;
5237 -- Start of processing for Why_Not_Static
5240 -- If in ACATS mode (debug flag 2), then suppress all these messages,
5241 -- this avoids massive updates to the ACATS base line.
5243 if Debug_Flag_2 then
5247 -- Ignore call on error or empty node
5249 if No (Expr) or else Nkind (Expr) = N_Error then
5253 -- Preprocessing for sub expressions
5255 if Nkind (Expr) in N_Subexpr then
5257 -- Nothing to do if expression is static
5259 if Is_OK_Static_Expression (Expr) then
5263 -- Test for constraint error raised
5265 if Raises_Constraint_Error (Expr) then
5267 ("expression raises exception, cannot be static " &
5268 "(RM 4.9(34))!", N);
5272 -- If no type, then something is pretty wrong, so ignore
5274 Typ := Etype (Expr);
5280 -- Type must be scalar or string type
5282 if not Is_Scalar_Type (Typ)
5283 and then not Is_String_Type (Typ)
5286 ("static expression must have scalar or string type " &
5292 -- If we got through those checks, test particular node kind
5295 when N_Expanded_Name | N_Identifier | N_Operator_Symbol =>
5298 if Is_Named_Number (E) then
5301 elsif Ekind (E) = E_Constant then
5302 if not Is_Static_Expression (Constant_Value (E)) then
5304 ("& is not a static constant (RM 4.9(5))!", N, E);
5309 ("& is not static constant or named number " &
5310 "(RM 4.9(5))!", N, E);
5313 when N_Binary_Op | N_Short_Circuit | N_Membership_Test =>
5314 if Nkind (N) in N_Op_Shift then
5316 ("shift functions are never static (RM 4.9(6,18))!", N);
5319 Why_Not_Static (Left_Opnd (N));
5320 Why_Not_Static (Right_Opnd (N));
5324 Why_Not_Static (Right_Opnd (N));
5326 when N_Attribute_Reference =>
5327 Why_Not_Static_List (Expressions (N));
5329 E := Etype (Prefix (N));
5331 if E = Standard_Void_Type then
5335 -- Special case non-scalar'Size since this is a common error
5337 if Attribute_Name (N) = Name_Size then
5339 ("size attribute is only static for static scalar type " &
5340 "(RM 4.9(7,8))", N);
5344 elsif Is_Array_Type (E) then
5345 if Attribute_Name (N) /= Name_First
5347 Attribute_Name (N) /= Name_Last
5349 Attribute_Name (N) /= Name_Length
5352 ("static array attribute must be Length, First, or Last " &
5355 -- Since we know the expression is not-static (we already
5356 -- tested for this, must mean array is not static).
5360 ("prefix is non-static array (RM 4.9(8))!", Prefix (N));
5365 -- Special case generic types, since again this is a common source
5368 elsif Is_Generic_Actual_Type (E)
5373 ("attribute of generic type is never static " &
5374 "(RM 4.9(7,8))!", N);
5376 elsif Is_Static_Subtype (E) then
5379 elsif Is_Scalar_Type (E) then
5381 ("prefix type for attribute is not static scalar subtype " &
5386 ("static attribute must apply to array/scalar type " &
5387 "(RM 4.9(7,8))!", N);
5390 when N_String_Literal =>
5392 ("subtype of string literal is non-static (RM 4.9(4))!", N);
5394 when N_Explicit_Dereference =>
5396 ("explicit dereference is never static (RM 4.9)!", N);
5398 when N_Function_Call =>
5399 Why_Not_Static_List (Parameter_Associations (N));
5400 Error_Msg_N ("non-static function call (RM 4.9(6,18))!", N);
5402 when N_Parameter_Association =>
5403 Why_Not_Static (Explicit_Actual_Parameter (N));
5405 when N_Indexed_Component =>
5407 ("indexed component is never static (RM 4.9)!", N);
5409 when N_Procedure_Call_Statement =>
5411 ("procedure call is never static (RM 4.9)!", N);
5413 when N_Qualified_Expression =>
5414 Why_Not_Static (Expression (N));
5416 when N_Aggregate | N_Extension_Aggregate =>
5418 ("an aggregate is never static (RM 4.9)!", N);
5421 Why_Not_Static (Low_Bound (N));
5422 Why_Not_Static (High_Bound (N));
5424 when N_Range_Constraint =>
5425 Why_Not_Static (Range_Expression (N));
5427 when N_Subtype_Indication =>
5428 Why_Not_Static (Constraint (N));
5430 when N_Selected_Component =>
5432 ("selected component is never static (RM 4.9)!", N);
5436 ("slice is never static (RM 4.9)!", N);
5438 when N_Type_Conversion =>
5439 Why_Not_Static (Expression (N));
5441 if not Is_Scalar_Type (Entity (Subtype_Mark (N)))
5442 or else not Is_Static_Subtype (Entity (Subtype_Mark (N)))
5445 ("static conversion requires static scalar subtype result " &
5449 when N_Unchecked_Type_Conversion =>
5451 ("unchecked type conversion is never static (RM 4.9)!", N);