1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree
; use Atree
;
27 with Checks
; use Checks
;
28 with Debug
; use Debug
;
29 with Einfo
; use Einfo
;
30 with Elists
; use Elists
;
31 with Errout
; use Errout
;
32 with Eval_Fat
; use Eval_Fat
;
33 with Exp_Util
; use Exp_Util
;
34 with Freeze
; use Freeze
;
36 with Namet
; use Namet
;
37 with Nmake
; use Nmake
;
38 with Nlists
; use Nlists
;
40 with Rtsfind
; use Rtsfind
;
42 with Sem_Aux
; use Sem_Aux
;
43 with Sem_Cat
; use Sem_Cat
;
44 with Sem_Ch6
; use Sem_Ch6
;
45 with Sem_Ch8
; use Sem_Ch8
;
46 with Sem_Res
; use Sem_Res
;
47 with Sem_Util
; use Sem_Util
;
48 with Sem_Type
; use Sem_Type
;
49 with Sem_Warn
; use Sem_Warn
;
50 with Sinfo
; use Sinfo
;
51 with Snames
; use Snames
;
52 with Stand
; use Stand
;
53 with Stringt
; use Stringt
;
54 with Tbuild
; use Tbuild
;
56 package body Sem_Eval
is
58 -----------------------------------------
59 -- Handling of Compile Time Evaluation --
60 -----------------------------------------
62 -- The compile time evaluation of expressions is distributed over several
63 -- Eval_xxx procedures. These procedures are called immediately after
64 -- a subexpression is resolved and is therefore accomplished in a bottom
65 -- up fashion. The flags are synthesized using the following approach.
67 -- Is_Static_Expression is determined by following the detailed rules
68 -- in RM 4.9(4-14). This involves testing the Is_Static_Expression
69 -- flag of the operands in many cases.
71 -- Raises_Constraint_Error is set if any of the operands have the flag
72 -- set or if an attempt to compute the value of the current expression
73 -- results in detection of a runtime constraint error.
75 -- As described in the spec, the requirement is that Is_Static_Expression
76 -- be accurately set, and in addition for nodes for which this flag is set,
77 -- Raises_Constraint_Error must also be set. Furthermore a node which has
78 -- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
79 -- requirement is that the expression value must be precomputed, and the
80 -- node is either a literal, or the name of a constant entity whose value
81 -- is a static expression.
83 -- The general approach is as follows. First compute Is_Static_Expression.
84 -- If the node is not static, then the flag is left off in the node and
85 -- we are all done. Otherwise for a static node, we test if any of the
86 -- operands will raise constraint error, and if so, propagate the flag
87 -- Raises_Constraint_Error to the result node and we are done (since the
88 -- error was already posted at a lower level).
90 -- For the case of a static node whose operands do not raise constraint
91 -- error, we attempt to evaluate the node. If this evaluation succeeds,
92 -- then the node is replaced by the result of this computation. If the
93 -- evaluation raises constraint error, then we rewrite the node with
94 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
95 -- to post appropriate error messages.
101 type Bits
is array (Nat
range <>) of Boolean;
102 -- Used to convert unsigned (modular) values for folding logical ops
104 -- The following definitions are used to maintain a cache of nodes that
105 -- have compile time known values. The cache is maintained only for
106 -- discrete types (the most common case), and is populated by calls to
107 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
108 -- since it is possible for the status to change (in particular it is
109 -- possible for a node to get replaced by a constraint error node).
111 CV_Bits
: constant := 5;
112 -- Number of low order bits of Node_Id value used to reference entries
113 -- in the cache table.
115 CV_Cache_Size
: constant Nat
:= 2 ** CV_Bits
;
116 -- Size of cache for compile time values
118 subtype CV_Range
is Nat
range 0 .. CV_Cache_Size
;
120 type CV_Entry
is record
125 type CV_Cache_Array
is array (CV_Range
) of CV_Entry
;
127 CV_Cache
: CV_Cache_Array
:= (others => (Node_High_Bound
, Uint_0
));
128 -- This is the actual cache, with entries consisting of node/value pairs,
129 -- and the impossible value Node_High_Bound used for unset entries.
131 type Range_Membership
is (In_Range
, Out_Of_Range
, Unknown
);
132 -- Range membership may either be statically known to be in range or out
133 -- of range, or not statically known. Used for Test_In_Range below.
135 -----------------------
136 -- Local Subprograms --
137 -----------------------
139 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
;
140 -- Converts a bit string of length B'Length to a Uint value to be used
141 -- for a target of type T, which is a modular type. This procedure
142 -- includes the necessary reduction by the modulus in the case of a
143 -- non-binary modulus (for a binary modulus, the bit string is the
144 -- right length any way so all is well).
146 function Get_String_Val
(N
: Node_Id
) return Node_Id
;
147 -- Given a tree node for a folded string or character value, returns
148 -- the corresponding string literal or character literal (one of the
149 -- two must be available, or the operand would not have been marked
150 -- as foldable in the earlier analysis of the operation).
152 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean;
153 -- Bits represents the number of bits in an integer value to be computed
154 -- (but the value has not been computed yet). If this value in Bits is
155 -- reasonable, a result of True is returned, with the implication that
156 -- the caller should go ahead and complete the calculation. If the value
157 -- in Bits is unreasonably large, then an error is posted on node N, and
158 -- False is returned (and the caller skips the proposed calculation).
160 procedure Out_Of_Range
(N
: Node_Id
);
161 -- This procedure is called if it is determined that node N, which
162 -- appears in a non-static context, is a compile time known value
163 -- which is outside its range, i.e. the range of Etype. This is used
164 -- in contexts where this is an illegality if N is static, and should
165 -- generate a warning otherwise.
167 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
);
168 -- N and Exp are nodes representing an expression, Exp is known
169 -- to raise CE. N is rewritten in term of Exp in the optimal way.
171 function String_Type_Len
(Stype
: Entity_Id
) return Uint
;
172 -- Given a string type, determines the length of the index type, or,
173 -- if this index type is non-static, the length of the base type of
174 -- this index type. Note that if the string type is itself static,
175 -- then the index type is static, so the second case applies only
176 -- if the string type passed is non-static.
178 function Test
(Cond
: Boolean) return Uint
;
179 pragma Inline
(Test
);
180 -- This function simply returns the appropriate Boolean'Pos value
181 -- corresponding to the value of Cond as a universal integer. It is
182 -- used for producing the result of the static evaluation of the
185 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
;
186 -- Check whether an arithmetic operation with universal operands which
187 -- is a rewritten function call with an explicit scope indication is
188 -- ambiguous: P."+" (1, 2) will be ambiguous if there is more than one
189 -- visible numeric type declared in P and the context does not impose a
190 -- type on the result (e.g. in the expression of a type conversion).
191 -- If ambiguous, emit an error and return Empty, else return the result
192 -- type of the operator.
194 procedure Test_Expression_Is_Foldable
199 -- Tests to see if expression N whose single operand is Op1 is foldable,
200 -- i.e. the operand value is known at compile time. If the operation is
201 -- foldable, then Fold is True on return, and Stat indicates whether
202 -- the result is static (i.e. the operand was static). Note that it
203 -- is quite possible for Fold to be True, and Stat to be False, since
204 -- there are cases in which we know the value of an operand even though
205 -- it is not technically static (e.g. the static lower bound of a range
206 -- whose upper bound is non-static).
208 -- If Stat is set False on return, then Test_Expression_Is_Foldable makes a
209 -- call to Check_Non_Static_Context on the operand. If Fold is False on
210 -- return, then all processing is complete, and the caller should
211 -- return, since there is nothing else to do.
213 -- If Stat is set True on return, then Is_Static_Expression is also set
214 -- true in node N. There are some cases where this is over-enthusiastic,
215 -- e.g. in the two operand case below, for string comparison, the result
216 -- is not static even though the two operands are static. In such cases,
217 -- the caller must reset the Is_Static_Expression flag in N.
219 -- If Fold and Stat are both set to False then this routine performs also
220 -- the following extra actions:
222 -- If either operand is Any_Type then propagate it to result to
223 -- prevent cascaded errors.
225 -- If some operand raises constraint error, then replace the node N
226 -- with the raise constraint error node. This replacement inherits the
227 -- Is_Static_Expression flag from the operands.
229 procedure Test_Expression_Is_Foldable
235 -- Same processing, except applies to an expression N with two operands
236 -- Op1 and Op2. The result is static only if both operands are static.
238 function Test_In_Range
241 Assume_Valid
: Boolean;
243 Int_Real
: Boolean) return Range_Membership
;
244 -- Common processing for Is_In_Range and Is_Out_Of_Range: Returns In_Range
245 -- or Out_Of_Range if it can be guaranteed at compile time that expression
246 -- N is known to be in or out of range of the subtype Typ. If not compile
247 -- time known, Unknown is returned. See documentation of Is_In_Range for
248 -- complete description of parameters.
250 procedure To_Bits
(U
: Uint
; B
: out Bits
);
251 -- Converts a Uint value to a bit string of length B'Length
253 ------------------------------
254 -- Check_Non_Static_Context --
255 ------------------------------
257 procedure Check_Non_Static_Context
(N
: Node_Id
) is
258 T
: constant Entity_Id
:= Etype
(N
);
259 Checks_On
: constant Boolean :=
260 not Index_Checks_Suppressed
(T
)
261 and not Range_Checks_Suppressed
(T
);
264 -- Ignore cases of non-scalar types, error types, or universal real
265 -- types that have no usable bounds.
268 or else not Is_Scalar_Type
(T
)
269 or else T
= Universal_Fixed
270 or else T
= Universal_Real
275 -- At this stage we have a scalar type. If we have an expression that
276 -- raises CE, then we already issued a warning or error msg so there
277 -- is nothing more to be done in this routine.
279 if Raises_Constraint_Error
(N
) then
283 -- Now we have a scalar type which is not marked as raising a constraint
284 -- error exception. The main purpose of this routine is to deal with
285 -- static expressions appearing in a non-static context. That means
286 -- that if we do not have a static expression then there is not much
287 -- to do. The one case that we deal with here is that if we have a
288 -- floating-point value that is out of range, then we post a warning
289 -- that an infinity will result.
291 if not Is_Static_Expression
(N
) then
292 if Is_Floating_Point_Type
(T
)
293 and then Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True)
296 ("??float value out of range, infinity will be generated", N
);
302 -- Here we have the case of outer level static expression of scalar
303 -- type, where the processing of this procedure is needed.
305 -- For real types, this is where we convert the value to a machine
306 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should only
307 -- need to do this if the parent is a constant declaration, since in
308 -- other cases, gigi should do the necessary conversion correctly, but
309 -- experimentation shows that this is not the case on all machines, in
310 -- particular if we do not convert all literals to machine values in
311 -- non-static contexts, then ACVC test C490001 fails on Sparc/Solaris
314 if Nkind
(N
) = N_Real_Literal
315 and then not Is_Machine_Number
(N
)
316 and then not Is_Generic_Type
(Etype
(N
))
317 and then Etype
(N
) /= Universal_Real
319 -- Check that value is in bounds before converting to machine
320 -- number, so as not to lose case where value overflows in the
321 -- least significant bit or less. See B490001.
323 if Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
328 -- Note: we have to copy the node, to avoid problems with conformance
329 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
331 Rewrite
(N
, New_Copy
(N
));
333 if not Is_Floating_Point_Type
(T
) then
335 (N
, Corresponding_Integer_Value
(N
) * Small_Value
(T
));
337 elsif not UR_Is_Zero
(Realval
(N
)) then
339 -- Note: even though RM 4.9(38) specifies biased rounding, this
340 -- has been modified by AI-100 in order to prevent confusing
341 -- differences in rounding between static and non-static
342 -- expressions. AI-100 specifies that the effect of such rounding
343 -- is implementation dependent, and in GNAT we round to nearest
344 -- even to match the run-time behavior.
347 (N
, Machine
(Base_Type
(T
), Realval
(N
), Round_Even
, N
));
350 Set_Is_Machine_Number
(N
);
353 -- Check for out of range universal integer. This is a non-static
354 -- context, so the integer value must be in range of the runtime
355 -- representation of universal integers.
357 -- We do this only within an expression, because that is the only
358 -- case in which non-static universal integer values can occur, and
359 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
360 -- called in contexts like the expression of a number declaration where
361 -- we certainly want to allow out of range values.
363 if Etype
(N
) = Universal_Integer
364 and then Nkind
(N
) = N_Integer_Literal
365 and then Nkind
(Parent
(N
)) in N_Subexpr
367 (Intval
(N
) < Expr_Value
(Type_Low_Bound
(Universal_Integer
))
369 Intval
(N
) > Expr_Value
(Type_High_Bound
(Universal_Integer
)))
371 Apply_Compile_Time_Constraint_Error
372 (N
, "non-static universal integer value out of range??",
373 CE_Range_Check_Failed
);
375 -- Check out of range of base type
377 elsif Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
380 -- Give warning if outside subtype (where one or both of the bounds of
381 -- the subtype is static). This warning is omitted if the expression
382 -- appears in a range that could be null (warnings are handled elsewhere
385 elsif T
/= Base_Type
(T
)
386 and then Nkind
(Parent
(N
)) /= N_Range
388 if Is_In_Range
(N
, T
, Assume_Valid
=> True) then
391 elsif Is_Out_Of_Range
(N
, T
, Assume_Valid
=> True) then
392 Apply_Compile_Time_Constraint_Error
393 (N
, "value not in range of}??", CE_Range_Check_Failed
);
396 Enable_Range_Check
(N
);
399 Set_Do_Range_Check
(N
, False);
402 end Check_Non_Static_Context
;
404 ---------------------------------
405 -- Check_String_Literal_Length --
406 ---------------------------------
408 procedure Check_String_Literal_Length
(N
: Node_Id
; Ttype
: Entity_Id
) is
410 if not Raises_Constraint_Error
(N
) and then Is_Constrained
(Ttype
) then
412 UI_From_Int
(String_Length
(Strval
(N
))) /= String_Type_Len
(Ttype
)
414 Apply_Compile_Time_Constraint_Error
415 (N
, "string length wrong for}??",
416 CE_Length_Check_Failed
,
421 end Check_String_Literal_Length
;
423 --------------------------
424 -- Compile_Time_Compare --
425 --------------------------
427 function Compile_Time_Compare
429 Assume_Valid
: Boolean) return Compare_Result
431 Discard
: aliased Uint
;
433 return Compile_Time_Compare
(L
, R
, Discard
'Access, Assume_Valid
);
434 end Compile_Time_Compare
;
436 function Compile_Time_Compare
439 Assume_Valid
: Boolean;
440 Rec
: Boolean := False) return Compare_Result
442 Ltyp
: Entity_Id
:= Underlying_Type
(Etype
(L
));
443 Rtyp
: Entity_Id
:= Underlying_Type
(Etype
(R
));
444 -- These get reset to the base type for the case of entities where
445 -- Is_Known_Valid is not set. This takes care of handling possible
446 -- invalid representations using the value of the base type, in
447 -- accordance with RM 13.9.1(10).
449 Discard
: aliased Uint
;
451 procedure Compare_Decompose
455 -- This procedure decomposes the node N into an expression node and a
456 -- signed offset, so that the value of N is equal to the value of R plus
457 -- the value V (which may be negative). If no such decomposition is
458 -- possible, then on return R is a copy of N, and V is set to zero.
460 function Compare_Fixup
(N
: Node_Id
) return Node_Id
;
461 -- This function deals with replacing 'Last and 'First references with
462 -- their corresponding type bounds, which we then can compare. The
463 -- argument is the original node, the result is the identity, unless we
464 -- have a 'Last/'First reference in which case the value returned is the
465 -- appropriate type bound.
467 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean;
468 -- Even if the context does not assume that values are valid, some
469 -- simple cases can be recognized.
471 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean;
472 -- Returns True iff L and R represent expressions that definitely have
473 -- identical (but not necessarily compile time known) values Indeed the
474 -- caller is expected to have already dealt with the cases of compile
475 -- time known values, so these are not tested here.
477 -----------------------
478 -- Compare_Decompose --
479 -----------------------
481 procedure Compare_Decompose
487 if Nkind
(N
) = N_Op_Add
488 and then Nkind
(Right_Opnd
(N
)) = N_Integer_Literal
491 V
:= Intval
(Right_Opnd
(N
));
494 elsif Nkind
(N
) = N_Op_Subtract
495 and then Nkind
(Right_Opnd
(N
)) = N_Integer_Literal
498 V
:= UI_Negate
(Intval
(Right_Opnd
(N
)));
501 elsif Nkind
(N
) = N_Attribute_Reference
then
502 if Attribute_Name
(N
) = Name_Succ
then
503 R
:= First
(Expressions
(N
));
507 elsif Attribute_Name
(N
) = Name_Pred
then
508 R
:= First
(Expressions
(N
));
516 end Compare_Decompose
;
522 function Compare_Fixup
(N
: Node_Id
) return Node_Id
is
528 -- Fixup only required for First/Last attribute reference
530 if Nkind
(N
) = N_Attribute_Reference
531 and then (Attribute_Name
(N
) = Name_First
533 Attribute_Name
(N
) = Name_Last
)
535 Xtyp
:= Etype
(Prefix
(N
));
537 -- If we have no type, then just abandon the attempt to do
538 -- a fixup, this is probably the result of some other error.
544 -- Dereference an access type
546 if Is_Access_Type
(Xtyp
) then
547 Xtyp
:= Designated_Type
(Xtyp
);
550 -- If we don't have an array type at this stage, something
551 -- is peculiar, e.g. another error, and we abandon the attempt
554 if not Is_Array_Type
(Xtyp
) then
558 -- Ignore unconstrained array, since bounds are not meaningful
560 if not Is_Constrained
(Xtyp
) then
564 if Ekind
(Xtyp
) = E_String_Literal_Subtype
then
565 if Attribute_Name
(N
) = Name_First
then
566 return String_Literal_Low_Bound
(Xtyp
);
569 return Make_Integer_Literal
(Sloc
(N
),
570 Intval
=> Intval
(String_Literal_Low_Bound
(Xtyp
))
571 + String_Literal_Length
(Xtyp
));
575 -- Find correct index type
577 Indx
:= First_Index
(Xtyp
);
579 if Present
(Expressions
(N
)) then
580 Subs
:= UI_To_Int
(Expr_Value
(First
(Expressions
(N
))));
582 for J
in 2 .. Subs
loop
583 Indx
:= Next_Index
(Indx
);
587 Xtyp
:= Etype
(Indx
);
589 if Attribute_Name
(N
) = Name_First
then
590 return Type_Low_Bound
(Xtyp
);
592 return Type_High_Bound
(Xtyp
);
599 ----------------------------
600 -- Is_Known_Valid_Operand --
601 ----------------------------
603 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean is
605 return (Is_Entity_Name
(Opnd
)
607 (Is_Known_Valid
(Entity
(Opnd
))
608 or else Ekind
(Entity
(Opnd
)) = E_In_Parameter
610 (Ekind
(Entity
(Opnd
)) in Object_Kind
611 and then Present
(Current_Value
(Entity
(Opnd
))))))
612 or else Is_OK_Static_Expression
(Opnd
);
613 end Is_Known_Valid_Operand
;
619 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean is
620 Lf
: constant Node_Id
:= Compare_Fixup
(L
);
621 Rf
: constant Node_Id
:= Compare_Fixup
(R
);
623 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean;
624 -- L, R are the Expressions values from two attribute nodes for First
625 -- or Last attributes. Either may be set to No_List if no expressions
626 -- are present (indicating subscript 1). The result is True if both
627 -- expressions represent the same subscript (note one case is where
628 -- one subscript is missing and the other is explicitly set to 1).
630 -----------------------
631 -- Is_Same_Subscript --
632 -----------------------
634 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean is
640 return Expr_Value
(First
(R
)) = Uint_1
;
645 return Expr_Value
(First
(L
)) = Uint_1
;
647 return Expr_Value
(First
(L
)) = Expr_Value
(First
(R
));
650 end Is_Same_Subscript
;
652 -- Start of processing for Is_Same_Value
655 -- Values are the same if they refer to the same entity and the
656 -- entity is non-volatile. This does not however apply to Float
657 -- types, since we may have two NaN values and they should never
660 -- If the entity is a discriminant, the two expressions may be bounds
661 -- of components of objects of the same discriminated type. The
662 -- values of the discriminants are not static, and therefore the
663 -- result is unknown.
665 -- It would be better to comment individual branches of this test ???
667 if Nkind_In
(Lf
, N_Identifier
, N_Expanded_Name
)
668 and then Nkind_In
(Rf
, N_Identifier
, N_Expanded_Name
)
669 and then Entity
(Lf
) = Entity
(Rf
)
670 and then Ekind
(Entity
(Lf
)) /= E_Discriminant
671 and then Present
(Entity
(Lf
))
672 and then not Is_Floating_Point_Type
(Etype
(L
))
673 and then not Is_Volatile_Reference
(L
)
674 and then not Is_Volatile_Reference
(R
)
678 -- Or if they are compile time known and identical
680 elsif Compile_Time_Known_Value
(Lf
)
682 Compile_Time_Known_Value
(Rf
)
683 and then Expr_Value
(Lf
) = Expr_Value
(Rf
)
687 -- False if Nkind of the two nodes is different for remaining cases
689 elsif Nkind
(Lf
) /= Nkind
(Rf
) then
692 -- True if both 'First or 'Last values applying to the same entity
693 -- (first and last don't change even if value does). Note that we
694 -- need this even with the calls to Compare_Fixup, to handle the
695 -- case of unconstrained array attributes where Compare_Fixup
696 -- cannot find useful bounds.
698 elsif Nkind
(Lf
) = N_Attribute_Reference
699 and then Attribute_Name
(Lf
) = Attribute_Name
(Rf
)
700 and then (Attribute_Name
(Lf
) = Name_First
702 Attribute_Name
(Lf
) = Name_Last
)
703 and then Nkind_In
(Prefix
(Lf
), N_Identifier
, N_Expanded_Name
)
704 and then Nkind_In
(Prefix
(Rf
), N_Identifier
, N_Expanded_Name
)
705 and then Entity
(Prefix
(Lf
)) = Entity
(Prefix
(Rf
))
706 and then Is_Same_Subscript
(Expressions
(Lf
), Expressions
(Rf
))
710 -- True if the same selected component from the same record
712 elsif Nkind
(Lf
) = N_Selected_Component
713 and then Selector_Name
(Lf
) = Selector_Name
(Rf
)
714 and then Is_Same_Value
(Prefix
(Lf
), Prefix
(Rf
))
718 -- True if the same unary operator applied to the same operand
720 elsif Nkind
(Lf
) in N_Unary_Op
721 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
725 -- True if the same binary operator applied to the same operands
727 elsif Nkind
(Lf
) in N_Binary_Op
728 and then Is_Same_Value
(Left_Opnd
(Lf
), Left_Opnd
(Rf
))
729 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
733 -- All other cases, we can't tell, so return False
740 -- Start of processing for Compile_Time_Compare
745 -- In preanalysis mode, always return Unknown unless the expression
746 -- is static. It is too early to be thinking we know the result of a
747 -- comparison, save that judgment for the full analysis. This is
748 -- particularly important in the case of pre and postconditions, which
749 -- otherwise can be prematurely collapsed into having True or False
750 -- conditions when this is inappropriate.
752 if not (Full_Analysis
753 or else (Is_Static_Expression
(L
)
755 Is_Static_Expression
(R
)))
760 -- If either operand could raise constraint error, then we cannot
761 -- know the result at compile time (since CE may be raised!)
763 if not (Cannot_Raise_Constraint_Error
(L
)
765 Cannot_Raise_Constraint_Error
(R
))
770 -- Identical operands are most certainly equal
775 -- If expressions have no types, then do not attempt to determine if
776 -- they are the same, since something funny is going on. One case in
777 -- which this happens is during generic template analysis, when bounds
778 -- are not fully analyzed.
780 elsif No
(Ltyp
) or else No
(Rtyp
) then
783 -- We do not attempt comparisons for packed arrays arrays represented as
784 -- modular types, where the semantics of comparison is quite different.
786 elsif Is_Packed_Array_Type
(Ltyp
)
787 and then Is_Modular_Integer_Type
(Ltyp
)
791 -- For access types, the only time we know the result at compile time
792 -- (apart from identical operands, which we handled already) is if we
793 -- know one operand is null and the other is not, or both operands are
796 elsif Is_Access_Type
(Ltyp
) then
797 if Known_Null
(L
) then
798 if Known_Null
(R
) then
800 elsif Known_Non_Null
(R
) then
806 elsif Known_Non_Null
(L
) and then Known_Null
(R
) then
813 -- Case where comparison involves two compile time known values
815 elsif Compile_Time_Known_Value
(L
)
816 and then Compile_Time_Known_Value
(R
)
818 -- For the floating-point case, we have to be a little careful, since
819 -- at compile time we are dealing with universal exact values, but at
820 -- runtime, these will be in non-exact target form. That's why the
821 -- returned results are LE and GE below instead of LT and GT.
823 if Is_Floating_Point_Type
(Ltyp
)
825 Is_Floating_Point_Type
(Rtyp
)
828 Lo
: constant Ureal
:= Expr_Value_R
(L
);
829 Hi
: constant Ureal
:= Expr_Value_R
(R
);
841 -- For string types, we have two string literals and we proceed to
842 -- compare them using the Ada style dictionary string comparison.
844 elsif not Is_Scalar_Type
(Ltyp
) then
846 Lstring
: constant String_Id
:= Strval
(Expr_Value_S
(L
));
847 Rstring
: constant String_Id
:= Strval
(Expr_Value_S
(R
));
848 Llen
: constant Nat
:= String_Length
(Lstring
);
849 Rlen
: constant Nat
:= String_Length
(Rstring
);
852 for J
in 1 .. Nat
'Min (Llen
, Rlen
) loop
854 LC
: constant Char_Code
:= Get_String_Char
(Lstring
, J
);
855 RC
: constant Char_Code
:= Get_String_Char
(Rstring
, J
);
867 elsif Llen
> Rlen
then
874 -- For remaining scalar cases we know exactly (note that this does
875 -- include the fixed-point case, where we know the run time integer
880 Lo
: constant Uint
:= Expr_Value
(L
);
881 Hi
: constant Uint
:= Expr_Value
(R
);
898 -- Cases where at least one operand is not known at compile time
901 -- Remaining checks apply only for discrete types
903 if not Is_Discrete_Type
(Ltyp
)
904 or else not Is_Discrete_Type
(Rtyp
)
909 -- Defend against generic types, or actually any expressions that
910 -- contain a reference to a generic type from within a generic
911 -- template. We don't want to do any range analysis of such
912 -- expressions for two reasons. First, the bounds of a generic type
913 -- itself are junk and cannot be used for any kind of analysis.
914 -- Second, we may have a case where the range at run time is indeed
915 -- known, but we don't want to do compile time analysis in the
916 -- template based on that range since in an instance the value may be
917 -- static, and able to be elaborated without reference to the bounds
918 -- of types involved. As an example, consider:
920 -- (F'Pos (F'Last) + 1) > Integer'Last
922 -- The expression on the left side of > is Universal_Integer and thus
923 -- acquires the type Integer for evaluation at run time, and at run
924 -- time it is true that this condition is always False, but within
925 -- an instance F may be a type with a static range greater than the
926 -- range of Integer, and the expression statically evaluates to True.
928 if References_Generic_Formal_Type
(L
)
930 References_Generic_Formal_Type
(R
)
935 -- Replace types by base types for the case of entities which are
936 -- not known to have valid representations. This takes care of
937 -- properly dealing with invalid representations.
939 if not Assume_Valid
and then not Assume_No_Invalid_Values
then
940 if Is_Entity_Name
(L
) and then not Is_Known_Valid
(Entity
(L
)) then
941 Ltyp
:= Underlying_Type
(Base_Type
(Ltyp
));
944 if Is_Entity_Name
(R
) and then not Is_Known_Valid
(Entity
(R
)) then
945 Rtyp
:= Underlying_Type
(Base_Type
(Rtyp
));
949 -- First attempt is to decompose the expressions to extract a
950 -- constant offset resulting from the use of any of the forms:
957 -- Then we see if the two expressions are the same value, and if so
958 -- the result is obtained by comparing the offsets.
960 -- Note: the reason we do this test first is that it returns only
961 -- decisive results (with diff set), where other tests, like the
962 -- range test, may not be as so decisive. Consider for example
963 -- J .. J + 1. This code can conclude LT with a difference of 1,
964 -- even if the range of J is not known.
973 Compare_Decompose
(L
, Lnode
, Loffs
);
974 Compare_Decompose
(R
, Rnode
, Roffs
);
976 if Is_Same_Value
(Lnode
, Rnode
) then
977 if Loffs
= Roffs
then
980 elsif Loffs
< Roffs
then
981 Diff
.all := Roffs
- Loffs
;
985 Diff
.all := Loffs
- Roffs
;
991 -- Next, try range analysis and see if operand ranges are disjoint
999 -- True if each range is a single point
1002 Determine_Range
(L
, LOK
, LLo
, LHi
, Assume_Valid
);
1003 Determine_Range
(R
, ROK
, RLo
, RHi
, Assume_Valid
);
1006 Single
:= (LLo
= LHi
) and then (RLo
= RHi
);
1009 if Single
and Assume_Valid
then
1010 Diff
.all := RLo
- LLo
;
1015 elsif RHi
< LLo
then
1016 if Single
and Assume_Valid
then
1017 Diff
.all := LLo
- RLo
;
1022 elsif Single
and then LLo
= RLo
then
1024 -- If the range includes a single literal and we can assume
1025 -- validity then the result is known even if an operand is
1028 if Assume_Valid
then
1034 elsif LHi
= RLo
then
1037 elsif RHi
= LLo
then
1040 elsif not Is_Known_Valid_Operand
(L
)
1041 and then not Assume_Valid
1043 if Is_Same_Value
(L
, R
) then
1050 -- If the range of either operand cannot be determined, nothing
1051 -- further can be inferred.
1058 -- Here is where we check for comparisons against maximum bounds of
1059 -- types, where we know that no value can be outside the bounds of
1060 -- the subtype. Note that this routine is allowed to assume that all
1061 -- expressions are within their subtype bounds. Callers wishing to
1062 -- deal with possibly invalid values must in any case take special
1063 -- steps (e.g. conversions to larger types) to avoid this kind of
1064 -- optimization, which is always considered to be valid. We do not
1065 -- attempt this optimization with generic types, since the type
1066 -- bounds may not be meaningful in this case.
1068 -- We are in danger of an infinite recursion here. It does not seem
1069 -- useful to go more than one level deep, so the parameter Rec is
1070 -- used to protect ourselves against this infinite recursion.
1074 -- See if we can get a decisive check against one operand and
1075 -- a bound of the other operand (four possible tests here).
1076 -- Note that we avoid testing junk bounds of a generic type.
1078 if not Is_Generic_Type
(Rtyp
) then
1079 case Compile_Time_Compare
(L
, Type_Low_Bound
(Rtyp
),
1081 Assume_Valid
, Rec
=> True)
1083 when LT
=> return LT
;
1084 when LE
=> return LE
;
1085 when EQ
=> return LE
;
1086 when others => null;
1089 case Compile_Time_Compare
(L
, Type_High_Bound
(Rtyp
),
1091 Assume_Valid
, Rec
=> True)
1093 when GT
=> return GT
;
1094 when GE
=> return GE
;
1095 when EQ
=> return GE
;
1096 when others => null;
1100 if not Is_Generic_Type
(Ltyp
) then
1101 case Compile_Time_Compare
(Type_Low_Bound
(Ltyp
), R
,
1103 Assume_Valid
, Rec
=> True)
1105 when GT
=> return GT
;
1106 when GE
=> return GE
;
1107 when EQ
=> return GE
;
1108 when others => null;
1111 case Compile_Time_Compare
(Type_High_Bound
(Ltyp
), R
,
1113 Assume_Valid
, Rec
=> True)
1115 when LT
=> return LT
;
1116 when LE
=> return LE
;
1117 when EQ
=> return LE
;
1118 when others => null;
1123 -- Next attempt is to see if we have an entity compared with a
1124 -- compile time known value, where there is a current value
1125 -- conditional for the entity which can tell us the result.
1129 -- Entity variable (left operand)
1132 -- Value (right operand)
1135 -- If False, we have reversed the operands
1138 -- Comparison operator kind from Get_Current_Value_Condition call
1141 -- Value from Get_Current_Value_Condition call
1146 Result
: Compare_Result
;
1147 -- Known result before inversion
1150 if Is_Entity_Name
(L
)
1151 and then Compile_Time_Known_Value
(R
)
1154 Val
:= Expr_Value
(R
);
1157 elsif Is_Entity_Name
(R
)
1158 and then Compile_Time_Known_Value
(L
)
1161 Val
:= Expr_Value
(L
);
1164 -- That was the last chance at finding a compile time result
1170 Get_Current_Value_Condition
(Var
, Op
, Opn
);
1172 -- That was the last chance, so if we got nothing return
1178 Opv
:= Expr_Value
(Opn
);
1180 -- We got a comparison, so we might have something interesting
1182 -- Convert LE to LT and GE to GT, just so we have fewer cases
1184 if Op
= N_Op_Le
then
1188 elsif Op
= N_Op_Ge
then
1193 -- Deal with equality case
1195 if Op
= N_Op_Eq
then
1198 elsif Opv
< Val
then
1204 -- Deal with inequality case
1206 elsif Op
= N_Op_Ne
then
1213 -- Deal with greater than case
1215 elsif Op
= N_Op_Gt
then
1218 elsif Opv
= Val
- 1 then
1224 -- Deal with less than case
1226 else pragma Assert
(Op
= N_Op_Lt
);
1229 elsif Opv
= Val
+ 1 then
1236 -- Deal with inverting result
1240 when GT
=> return LT
;
1241 when GE
=> return LE
;
1242 when LT
=> return GT
;
1243 when LE
=> return GE
;
1244 when others => return Result
;
1251 end Compile_Time_Compare
;
1253 -------------------------------
1254 -- Compile_Time_Known_Bounds --
1255 -------------------------------
1257 function Compile_Time_Known_Bounds
(T
: Entity_Id
) return Boolean is
1262 if not Is_Array_Type
(T
) then
1266 Indx
:= First_Index
(T
);
1267 while Present
(Indx
) loop
1268 Typ
:= Underlying_Type
(Etype
(Indx
));
1270 -- Never look at junk bounds of a generic type
1272 if Is_Generic_Type
(Typ
) then
1276 -- Otherwise check bounds for compile time known
1278 if not Compile_Time_Known_Value
(Type_Low_Bound
(Typ
)) then
1280 elsif not Compile_Time_Known_Value
(Type_High_Bound
(Typ
)) then
1288 end Compile_Time_Known_Bounds
;
1290 ------------------------------
1291 -- Compile_Time_Known_Value --
1292 ------------------------------
1294 function Compile_Time_Known_Value
(Op
: Node_Id
) return Boolean is
1295 K
: constant Node_Kind
:= Nkind
(Op
);
1296 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(Op
) mod CV_Cache_Size
);
1299 -- Never known at compile time if bad type or raises constraint error
1300 -- or empty (latter case occurs only as a result of a previous error).
1303 Check_Error_Detected
;
1307 or else Etype
(Op
) = Any_Type
1308 or else Raises_Constraint_Error
(Op
)
1313 -- If this is not a static expression or a null literal, and we are in
1314 -- configurable run-time mode, then we consider it not known at compile
1315 -- time. This avoids anomalies where whether something is allowed with a
1316 -- given configurable run-time library depends on how good the compiler
1317 -- is at optimizing and knowing that things are constant when they are
1320 if Configurable_Run_Time_Mode
1321 and then K
/= N_Null
1322 and then not Is_Static_Expression
(Op
)
1324 -- We make an exception for expressions that evaluate to True/False,
1325 -- to suppress spurious checks in ZFP mode. So far we have not seen
1326 -- any negative consequences of this exception.
1328 if Is_Entity_Name
(Op
)
1329 and then Ekind
(Entity
(Op
)) = E_Enumeration_Literal
1330 and then Etype
(Entity
(Op
)) = Standard_Boolean
1339 -- If we have an entity name, then see if it is the name of a constant
1340 -- and if so, test the corresponding constant value, or the name of
1341 -- an enumeration literal, which is always a constant.
1343 if Present
(Etype
(Op
)) and then Is_Entity_Name
(Op
) then
1345 E
: constant Entity_Id
:= Entity
(Op
);
1349 -- Never known at compile time if it is a packed array value.
1350 -- We might want to try to evaluate these at compile time one
1351 -- day, but we do not make that attempt now.
1353 if Is_Packed_Array_Type
(Etype
(Op
)) then
1357 if Ekind
(E
) = E_Enumeration_Literal
then
1360 -- In Alfa mode, the value of deferred constants should be ignored
1361 -- outside the scope of their full view. This allows parameterized
1362 -- formal verification, in which a deferred constant value if not
1363 -- known from client units.
1365 elsif Ekind
(E
) = E_Constant
1366 and then not (Alfa_Mode
1367 and then Present
(Full_View
(E
))
1368 and then not In_Open_Scopes
(Scope
(E
)))
1370 V
:= Constant_Value
(E
);
1371 return Present
(V
) and then Compile_Time_Known_Value
(V
);
1375 -- We have a value, see if it is compile time known
1378 -- Integer literals are worth storing in the cache
1380 if K
= N_Integer_Literal
then
1382 CV_Ent
.V
:= Intval
(Op
);
1385 -- Other literals and NULL are known at compile time
1388 K
= N_Character_Literal
1392 K
= N_String_Literal
1398 -- Any reference to Null_Parameter is known at compile time. No
1399 -- other attribute references (that have not already been folded)
1400 -- are known at compile time.
1402 elsif K
= N_Attribute_Reference
then
1403 return Attribute_Name
(Op
) = Name_Null_Parameter
;
1407 -- If we fall through, not known at compile time
1411 -- If we get an exception while trying to do this test, then some error
1412 -- has occurred, and we simply say that the value is not known after all
1417 end Compile_Time_Known_Value
;
1419 --------------------------------------
1420 -- Compile_Time_Known_Value_Or_Aggr --
1421 --------------------------------------
1423 function Compile_Time_Known_Value_Or_Aggr
(Op
: Node_Id
) return Boolean is
1425 -- If we have an entity name, then see if it is the name of a constant
1426 -- and if so, test the corresponding constant value, or the name of
1427 -- an enumeration literal, which is always a constant.
1429 if Is_Entity_Name
(Op
) then
1431 E
: constant Entity_Id
:= Entity
(Op
);
1435 if Ekind
(E
) = E_Enumeration_Literal
then
1438 elsif Ekind
(E
) /= E_Constant
then
1442 V
:= Constant_Value
(E
);
1444 and then Compile_Time_Known_Value_Or_Aggr
(V
);
1448 -- We have a value, see if it is compile time known
1451 if Compile_Time_Known_Value
(Op
) then
1454 elsif Nkind
(Op
) = N_Aggregate
then
1456 if Present
(Expressions
(Op
)) then
1461 Expr
:= First
(Expressions
(Op
));
1462 while Present
(Expr
) loop
1463 if not Compile_Time_Known_Value_Or_Aggr
(Expr
) then
1472 if Present
(Component_Associations
(Op
)) then
1477 Cass
:= First
(Component_Associations
(Op
));
1478 while Present
(Cass
) loop
1480 Compile_Time_Known_Value_Or_Aggr
(Expression
(Cass
))
1492 -- All other types of values are not known at compile time
1499 end Compile_Time_Known_Value_Or_Aggr
;
1505 -- This is only called for actuals of functions that are not predefined
1506 -- operators (which have already been rewritten as operators at this
1507 -- stage), so the call can never be folded, and all that needs doing for
1508 -- the actual is to do the check for a non-static context.
1510 procedure Eval_Actual
(N
: Node_Id
) is
1512 Check_Non_Static_Context
(N
);
1515 --------------------
1516 -- Eval_Allocator --
1517 --------------------
1519 -- Allocators are never static, so all we have to do is to do the
1520 -- check for a non-static context if an expression is present.
1522 procedure Eval_Allocator
(N
: Node_Id
) is
1523 Expr
: constant Node_Id
:= Expression
(N
);
1526 if Nkind
(Expr
) = N_Qualified_Expression
then
1527 Check_Non_Static_Context
(Expression
(Expr
));
1531 ------------------------
1532 -- Eval_Arithmetic_Op --
1533 ------------------------
1535 -- Arithmetic operations are static functions, so the result is static
1536 -- if both operands are static (RM 4.9(7), 4.9(20)).
1538 procedure Eval_Arithmetic_Op
(N
: Node_Id
) is
1539 Left
: constant Node_Id
:= Left_Opnd
(N
);
1540 Right
: constant Node_Id
:= Right_Opnd
(N
);
1541 Ltype
: constant Entity_Id
:= Etype
(Left
);
1542 Rtype
: constant Entity_Id
:= Etype
(Right
);
1543 Otype
: Entity_Id
:= Empty
;
1548 -- If not foldable we are done
1550 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
1556 if Is_Universal_Numeric_Type
(Etype
(Left
))
1558 Is_Universal_Numeric_Type
(Etype
(Right
))
1560 Otype
:= Find_Universal_Operator_Type
(N
);
1563 -- Fold for cases where both operands are of integer type
1565 if Is_Integer_Type
(Ltype
) and then Is_Integer_Type
(Rtype
) then
1567 Left_Int
: constant Uint
:= Expr_Value
(Left
);
1568 Right_Int
: constant Uint
:= Expr_Value
(Right
);
1575 Result
:= Left_Int
+ Right_Int
;
1577 when N_Op_Subtract
=>
1578 Result
:= Left_Int
- Right_Int
;
1580 when N_Op_Multiply
=>
1583 (Num_Bits
(Left_Int
) + Num_Bits
(Right_Int
)))
1585 Result
:= Left_Int
* Right_Int
;
1592 -- The exception Constraint_Error is raised by integer
1593 -- division, rem and mod if the right operand is zero.
1595 if Right_Int
= 0 then
1596 Apply_Compile_Time_Constraint_Error
1597 (N
, "division by zero",
1603 Result
:= Left_Int
/ Right_Int
;
1608 -- The exception Constraint_Error is raised by integer
1609 -- division, rem and mod if the right operand is zero.
1611 if Right_Int
= 0 then
1612 Apply_Compile_Time_Constraint_Error
1613 (N
, "mod with zero divisor",
1618 Result
:= Left_Int
mod Right_Int
;
1623 -- The exception Constraint_Error is raised by integer
1624 -- division, rem and mod if the right operand is zero.
1626 if Right_Int
= 0 then
1627 Apply_Compile_Time_Constraint_Error
1628 (N
, "rem with zero divisor",
1634 Result
:= Left_Int
rem Right_Int
;
1638 raise Program_Error
;
1641 -- Adjust the result by the modulus if the type is a modular type
1643 if Is_Modular_Integer_Type
(Ltype
) then
1644 Result
:= Result
mod Modulus
(Ltype
);
1646 -- For a signed integer type, check non-static overflow
1648 elsif (not Stat
) and then Is_Signed_Integer_Type
(Ltype
) then
1650 BT
: constant Entity_Id
:= Base_Type
(Ltype
);
1651 Lo
: constant Uint
:= Expr_Value
(Type_Low_Bound
(BT
));
1652 Hi
: constant Uint
:= Expr_Value
(Type_High_Bound
(BT
));
1654 if Result
< Lo
or else Result
> Hi
then
1655 Apply_Compile_Time_Constraint_Error
1656 (N
, "value not in range of }??",
1657 CE_Overflow_Check_Failed
,
1664 -- If we get here we can fold the result
1666 Fold_Uint
(N
, Result
, Stat
);
1669 -- Cases where at least one operand is a real. We handle the cases of
1670 -- both reals, or mixed/real integer cases (the latter happen only for
1671 -- divide and multiply, and the result is always real).
1673 elsif Is_Real_Type
(Ltype
) or else Is_Real_Type
(Rtype
) then
1680 if Is_Real_Type
(Ltype
) then
1681 Left_Real
:= Expr_Value_R
(Left
);
1683 Left_Real
:= UR_From_Uint
(Expr_Value
(Left
));
1686 if Is_Real_Type
(Rtype
) then
1687 Right_Real
:= Expr_Value_R
(Right
);
1689 Right_Real
:= UR_From_Uint
(Expr_Value
(Right
));
1692 if Nkind
(N
) = N_Op_Add
then
1693 Result
:= Left_Real
+ Right_Real
;
1695 elsif Nkind
(N
) = N_Op_Subtract
then
1696 Result
:= Left_Real
- Right_Real
;
1698 elsif Nkind
(N
) = N_Op_Multiply
then
1699 Result
:= Left_Real
* Right_Real
;
1701 else pragma Assert
(Nkind
(N
) = N_Op_Divide
);
1702 if UR_Is_Zero
(Right_Real
) then
1703 Apply_Compile_Time_Constraint_Error
1704 (N
, "division by zero", CE_Divide_By_Zero
);
1708 Result
:= Left_Real
/ Right_Real
;
1711 Fold_Ureal
(N
, Result
, Stat
);
1715 -- If the operator was resolved to a specific type, make sure that type
1716 -- is frozen even if the expression is folded into a literal (which has
1717 -- a universal type).
1719 if Present
(Otype
) then
1720 Freeze_Before
(N
, Otype
);
1722 end Eval_Arithmetic_Op
;
1724 ----------------------------
1725 -- Eval_Character_Literal --
1726 ----------------------------
1728 -- Nothing to be done!
1730 procedure Eval_Character_Literal
(N
: Node_Id
) is
1731 pragma Warnings
(Off
, N
);
1734 end Eval_Character_Literal
;
1740 -- Static function calls are either calls to predefined operators
1741 -- with static arguments, or calls to functions that rename a literal.
1742 -- Only the latter case is handled here, predefined operators are
1743 -- constant-folded elsewhere.
1745 -- If the function is itself inherited (see 7423-001) the literal of
1746 -- the parent type must be explicitly converted to the return type
1749 procedure Eval_Call
(N
: Node_Id
) is
1750 Loc
: constant Source_Ptr
:= Sloc
(N
);
1751 Typ
: constant Entity_Id
:= Etype
(N
);
1755 if Nkind
(N
) = N_Function_Call
1756 and then No
(Parameter_Associations
(N
))
1757 and then Is_Entity_Name
(Name
(N
))
1758 and then Present
(Alias
(Entity
(Name
(N
))))
1759 and then Is_Enumeration_Type
(Base_Type
(Typ
))
1761 Lit
:= Ultimate_Alias
(Entity
(Name
(N
)));
1763 if Ekind
(Lit
) = E_Enumeration_Literal
then
1764 if Base_Type
(Etype
(Lit
)) /= Base_Type
(Typ
) then
1766 (N
, Convert_To
(Typ
, New_Occurrence_Of
(Lit
, Loc
)));
1768 Rewrite
(N
, New_Occurrence_Of
(Lit
, Loc
));
1776 --------------------------
1777 -- Eval_Case_Expression --
1778 --------------------------
1780 -- A conditional expression is static if all its conditions and dependent
1781 -- expressions are static.
1783 procedure Eval_Case_Expression
(N
: Node_Id
) is
1786 Is_Static
: Boolean;
1794 if Is_Static_Expression
(Expression
(N
)) then
1795 Val
:= Expr_Value
(Expression
(N
));
1798 Check_Non_Static_Context
(Expression
(N
));
1802 Alt
:= First
(Alternatives
(N
));
1804 Search
: while Present
(Alt
) loop
1806 or else not Is_Static_Expression
(Expression
(Alt
))
1808 Check_Non_Static_Context
(Expression
(Alt
));
1812 Choice
:= First
(Discrete_Choices
(Alt
));
1813 while Present
(Choice
) loop
1814 if Nkind
(Choice
) = N_Others_Choice
then
1815 Result
:= Expression
(Alt
);
1818 elsif Expr_Value
(Choice
) = Val
then
1819 Result
:= Expression
(Alt
);
1832 Rewrite
(N
, Relocate_Node
(Result
));
1835 Set_Is_Static_Expression
(N
, False);
1837 end Eval_Case_Expression
;
1839 ------------------------
1840 -- Eval_Concatenation --
1841 ------------------------
1843 -- Concatenation is a static function, so the result is static if both
1844 -- operands are static (RM 4.9(7), 4.9(21)).
1846 procedure Eval_Concatenation
(N
: Node_Id
) is
1847 Left
: constant Node_Id
:= Left_Opnd
(N
);
1848 Right
: constant Node_Id
:= Right_Opnd
(N
);
1849 C_Typ
: constant Entity_Id
:= Root_Type
(Component_Type
(Etype
(N
)));
1854 -- Concatenation is never static in Ada 83, so if Ada 83 check operand
1855 -- non-static context.
1857 if Ada_Version
= Ada_83
1858 and then Comes_From_Source
(N
)
1860 Check_Non_Static_Context
(Left
);
1861 Check_Non_Static_Context
(Right
);
1865 -- If not foldable we are done. In principle concatenation that yields
1866 -- any string type is static (i.e. an array type of character types).
1867 -- However, character types can include enumeration literals, and
1868 -- concatenation in that case cannot be described by a literal, so we
1869 -- only consider the operation static if the result is an array of
1870 -- (a descendant of) a predefined character type.
1872 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
1874 if not (Is_Standard_Character_Type
(C_Typ
) and then Fold
) then
1875 Set_Is_Static_Expression
(N
, False);
1879 -- Compile time string concatenation
1881 -- ??? Note that operands that are aggregates can be marked as static,
1882 -- so we should attempt at a later stage to fold concatenations with
1886 Left_Str
: constant Node_Id
:= Get_String_Val
(Left
);
1888 Right_Str
: constant Node_Id
:= Get_String_Val
(Right
);
1889 Folded_Val
: String_Id
;
1892 -- Establish new string literal, and store left operand. We make
1893 -- sure to use the special Start_String that takes an operand if
1894 -- the left operand is a string literal. Since this is optimized
1895 -- in the case where that is the most recently created string
1896 -- literal, we ensure efficient time/space behavior for the
1897 -- case of a concatenation of a series of string literals.
1899 if Nkind
(Left_Str
) = N_String_Literal
then
1900 Left_Len
:= String_Length
(Strval
(Left_Str
));
1902 -- If the left operand is the empty string, and the right operand
1903 -- is a string literal (the case of "" & "..."), the result is the
1904 -- value of the right operand. This optimization is important when
1905 -- Is_Folded_In_Parser, to avoid copying an enormous right
1908 if Left_Len
= 0 and then Nkind
(Right_Str
) = N_String_Literal
then
1909 Folded_Val
:= Strval
(Right_Str
);
1911 Start_String
(Strval
(Left_Str
));
1916 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Left_Str
)));
1920 -- Now append the characters of the right operand, unless we
1921 -- optimized the "" & "..." case above.
1923 if Nkind
(Right_Str
) = N_String_Literal
then
1924 if Left_Len
/= 0 then
1925 Store_String_Chars
(Strval
(Right_Str
));
1926 Folded_Val
:= End_String
;
1929 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Right_Str
)));
1930 Folded_Val
:= End_String
;
1933 Set_Is_Static_Expression
(N
, Stat
);
1937 -- If left operand is the empty string, the result is the
1938 -- right operand, including its bounds if anomalous.
1941 and then Is_Array_Type
(Etype
(Right
))
1942 and then Etype
(Right
) /= Any_String
1944 Set_Etype
(N
, Etype
(Right
));
1947 Fold_Str
(N
, Folded_Val
, Static
=> True);
1950 end Eval_Concatenation
;
1952 ----------------------
1953 -- Eval_Entity_Name --
1954 ----------------------
1956 -- This procedure is used for identifiers and expanded names other than
1957 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
1958 -- static if they denote a static constant (RM 4.9(6)) or if the name
1959 -- denotes an enumeration literal (RM 4.9(22)).
1961 procedure Eval_Entity_Name
(N
: Node_Id
) is
1962 Def_Id
: constant Entity_Id
:= Entity
(N
);
1966 -- Enumeration literals are always considered to be constants
1967 -- and cannot raise constraint error (RM 4.9(22)).
1969 if Ekind
(Def_Id
) = E_Enumeration_Literal
then
1970 Set_Is_Static_Expression
(N
);
1973 -- A name is static if it denotes a static constant (RM 4.9(5)), and
1974 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
1975 -- it does not violate 10.2.1(8) here, since this is not a variable.
1977 elsif Ekind
(Def_Id
) = E_Constant
then
1979 -- Deferred constants must always be treated as nonstatic
1980 -- outside the scope of their full view.
1982 if Present
(Full_View
(Def_Id
))
1983 and then not In_Open_Scopes
(Scope
(Def_Id
))
1987 Val
:= Constant_Value
(Def_Id
);
1990 if Present
(Val
) then
1991 Set_Is_Static_Expression
1992 (N
, Is_Static_Expression
(Val
)
1993 and then Is_Static_Subtype
(Etype
(Def_Id
)));
1994 Set_Raises_Constraint_Error
(N
, Raises_Constraint_Error
(Val
));
1996 if not Is_Static_Expression
(N
)
1997 and then not Is_Generic_Type
(Etype
(N
))
1999 Validate_Static_Object_Name
(N
);
2006 -- Fall through if the name is not static
2008 Validate_Static_Object_Name
(N
);
2009 end Eval_Entity_Name
;
2011 ------------------------
2012 -- Eval_If_Expression --
2013 ------------------------
2015 -- We can fold to a static expression if the condition and both dependent
2016 -- expressions are static. Otherwise, the only required processing is to do
2017 -- the check for non-static context for the then and else expressions.
2019 procedure Eval_If_Expression
(N
: Node_Id
) is
2020 Condition
: constant Node_Id
:= First
(Expressions
(N
));
2021 Then_Expr
: constant Node_Id
:= Next
(Condition
);
2022 Else_Expr
: constant Node_Id
:= Next
(Then_Expr
);
2024 Non_Result
: Node_Id
;
2026 Rstat
: constant Boolean :=
2027 Is_Static_Expression
(Condition
)
2029 Is_Static_Expression
(Then_Expr
)
2031 Is_Static_Expression
(Else_Expr
);
2034 -- If any operand is Any_Type, just propagate to result and do not try
2035 -- to fold, this prevents cascaded errors.
2037 if Etype
(Condition
) = Any_Type
or else
2038 Etype
(Then_Expr
) = Any_Type
or else
2039 Etype
(Else_Expr
) = Any_Type
2041 Set_Etype
(N
, Any_Type
);
2042 Set_Is_Static_Expression
(N
, False);
2045 -- Static case where we can fold. Note that we don't try to fold cases
2046 -- where the condition is known at compile time, but the result is
2047 -- non-static. This avoids possible cases of infinite recursion where
2048 -- the expander puts in a redundant test and we remove it. Instead we
2049 -- deal with these cases in the expander.
2053 -- Select result operand
2055 if Is_True
(Expr_Value
(Condition
)) then
2056 Result
:= Then_Expr
;
2057 Non_Result
:= Else_Expr
;
2059 Result
:= Else_Expr
;
2060 Non_Result
:= Then_Expr
;
2063 -- Note that it does not matter if the non-result operand raises a
2064 -- Constraint_Error, but if the result raises constraint error then
2065 -- we replace the node with a raise constraint error. This will
2066 -- properly propagate Raises_Constraint_Error since this flag is
2069 if Raises_Constraint_Error
(Result
) then
2070 Rewrite_In_Raise_CE
(N
, Result
);
2071 Check_Non_Static_Context
(Non_Result
);
2073 -- Otherwise the result operand replaces the original node
2076 Rewrite
(N
, Relocate_Node
(Result
));
2079 -- Case of condition not known at compile time
2082 Check_Non_Static_Context
(Condition
);
2083 Check_Non_Static_Context
(Then_Expr
);
2084 Check_Non_Static_Context
(Else_Expr
);
2087 Set_Is_Static_Expression
(N
, Rstat
);
2088 end Eval_If_Expression
;
2090 ----------------------------
2091 -- Eval_Indexed_Component --
2092 ----------------------------
2094 -- Indexed components are never static, so we need to perform the check
2095 -- for non-static context on the index values. Then, we check if the
2096 -- value can be obtained at compile time, even though it is non-static.
2098 procedure Eval_Indexed_Component
(N
: Node_Id
) is
2102 -- Check for non-static context on index values
2104 Expr
:= First
(Expressions
(N
));
2105 while Present
(Expr
) loop
2106 Check_Non_Static_Context
(Expr
);
2110 -- If the indexed component appears in an object renaming declaration
2111 -- then we do not want to try to evaluate it, since in this case we
2112 -- need the identity of the array element.
2114 if Nkind
(Parent
(N
)) = N_Object_Renaming_Declaration
then
2117 -- Similarly if the indexed component appears as the prefix of an
2118 -- attribute we don't want to evaluate it, because at least for
2119 -- some cases of attributes we need the identify (e.g. Access, Size)
2121 elsif Nkind
(Parent
(N
)) = N_Attribute_Reference
then
2125 -- Note: there are other cases, such as the left side of an assignment,
2126 -- or an OUT parameter for a call, where the replacement results in the
2127 -- illegal use of a constant, But these cases are illegal in the first
2128 -- place, so the replacement, though silly, is harmless.
2130 -- Now see if this is a constant array reference
2132 if List_Length
(Expressions
(N
)) = 1
2133 and then Is_Entity_Name
(Prefix
(N
))
2134 and then Ekind
(Entity
(Prefix
(N
))) = E_Constant
2135 and then Present
(Constant_Value
(Entity
(Prefix
(N
))))
2138 Loc
: constant Source_Ptr
:= Sloc
(N
);
2139 Arr
: constant Node_Id
:= Constant_Value
(Entity
(Prefix
(N
)));
2140 Sub
: constant Node_Id
:= First
(Expressions
(N
));
2146 -- Linear one's origin subscript value for array reference
2149 -- Lower bound of the first array index
2152 -- Value from constant array
2155 Atyp
:= Etype
(Arr
);
2157 if Is_Access_Type
(Atyp
) then
2158 Atyp
:= Designated_Type
(Atyp
);
2161 -- If we have an array type (we should have but perhaps there are
2162 -- error cases where this is not the case), then see if we can do
2163 -- a constant evaluation of the array reference.
2165 if Is_Array_Type
(Atyp
) and then Atyp
/= Any_Composite
then
2166 if Ekind
(Atyp
) = E_String_Literal_Subtype
then
2167 Lbd
:= String_Literal_Low_Bound
(Atyp
);
2169 Lbd
:= Type_Low_Bound
(Etype
(First_Index
(Atyp
)));
2172 if Compile_Time_Known_Value
(Sub
)
2173 and then Nkind
(Arr
) = N_Aggregate
2174 and then Compile_Time_Known_Value
(Lbd
)
2175 and then Is_Discrete_Type
(Component_Type
(Atyp
))
2177 Lin
:= UI_To_Int
(Expr_Value
(Sub
) - Expr_Value
(Lbd
)) + 1;
2179 if List_Length
(Expressions
(Arr
)) >= Lin
then
2180 Elm
:= Pick
(Expressions
(Arr
), Lin
);
2182 -- If the resulting expression is compile time known,
2183 -- then we can rewrite the indexed component with this
2184 -- value, being sure to mark the result as non-static.
2185 -- We also reset the Sloc, in case this generates an
2186 -- error later on (e.g. 136'Access).
2188 if Compile_Time_Known_Value
(Elm
) then
2189 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2190 Set_Is_Static_Expression
(N
, False);
2195 -- We can also constant-fold if the prefix is a string literal.
2196 -- This will be useful in an instantiation or an inlining.
2198 elsif Compile_Time_Known_Value
(Sub
)
2199 and then Nkind
(Arr
) = N_String_Literal
2200 and then Compile_Time_Known_Value
(Lbd
)
2201 and then Expr_Value
(Lbd
) = 1
2202 and then Expr_Value
(Sub
) <=
2203 String_Literal_Length
(Etype
(Arr
))
2206 C
: constant Char_Code
:=
2207 Get_String_Char
(Strval
(Arr
),
2208 UI_To_Int
(Expr_Value
(Sub
)));
2210 Set_Character_Literal_Name
(C
);
2213 Make_Character_Literal
(Loc
,
2215 Char_Literal_Value
=> UI_From_CC
(C
));
2216 Set_Etype
(Elm
, Component_Type
(Atyp
));
2217 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2218 Set_Is_Static_Expression
(N
, False);
2224 end Eval_Indexed_Component
;
2226 --------------------------
2227 -- Eval_Integer_Literal --
2228 --------------------------
2230 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2231 -- as static by the analyzer. The reason we did it that early is to allow
2232 -- the possibility of turning off the Is_Static_Expression flag after
2233 -- analysis, but before resolution, when integer literals are generated in
2234 -- the expander that do not correspond to static expressions.
2236 procedure Eval_Integer_Literal
(N
: Node_Id
) is
2237 T
: constant Entity_Id
:= Etype
(N
);
2239 function In_Any_Integer_Context
return Boolean;
2240 -- If the literal is resolved with a specific type in a context where
2241 -- the expected type is Any_Integer, there are no range checks on the
2242 -- literal. By the time the literal is evaluated, it carries the type
2243 -- imposed by the enclosing expression, and we must recover the context
2244 -- to determine that Any_Integer is meant.
2246 ----------------------------
2247 -- In_Any_Integer_Context --
2248 ----------------------------
2250 function In_Any_Integer_Context
return Boolean is
2251 Par
: constant Node_Id
:= Parent
(N
);
2252 K
: constant Node_Kind
:= Nkind
(Par
);
2255 -- Any_Integer also appears in digits specifications for real types,
2256 -- but those have bounds smaller that those of any integer base type,
2257 -- so we can safely ignore these cases.
2259 return K
= N_Number_Declaration
2260 or else K
= N_Attribute_Reference
2261 or else K
= N_Attribute_Definition_Clause
2262 or else K
= N_Modular_Type_Definition
2263 or else K
= N_Signed_Integer_Type_Definition
;
2264 end In_Any_Integer_Context
;
2266 -- Start of processing for Eval_Integer_Literal
2270 -- If the literal appears in a non-expression context, then it is
2271 -- certainly appearing in a non-static context, so check it. This is
2272 -- actually a redundant check, since Check_Non_Static_Context would
2273 -- check it, but it seems worth while avoiding the call.
2275 if Nkind
(Parent
(N
)) not in N_Subexpr
2276 and then not In_Any_Integer_Context
2278 Check_Non_Static_Context
(N
);
2281 -- Modular integer literals must be in their base range
2283 if Is_Modular_Integer_Type
(T
)
2284 and then Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True)
2288 end Eval_Integer_Literal
;
2290 ---------------------
2291 -- Eval_Logical_Op --
2292 ---------------------
2294 -- Logical operations are static functions, so the result is potentially
2295 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2297 procedure Eval_Logical_Op
(N
: Node_Id
) is
2298 Left
: constant Node_Id
:= Left_Opnd
(N
);
2299 Right
: constant Node_Id
:= Right_Opnd
(N
);
2304 -- If not foldable we are done
2306 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2312 -- Compile time evaluation of logical operation
2315 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2316 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2319 -- VMS includes bitwise operations on signed types
2321 if Is_Modular_Integer_Type
(Etype
(N
))
2322 or else Is_VMS_Operator
(Entity
(N
))
2325 Left_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2326 Right_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2329 To_Bits
(Left_Int
, Left_Bits
);
2330 To_Bits
(Right_Int
, Right_Bits
);
2332 -- Note: should really be able to use array ops instead of
2333 -- these loops, but they weren't working at the time ???
2335 if Nkind
(N
) = N_Op_And
then
2336 for J
in Left_Bits
'Range loop
2337 Left_Bits
(J
) := Left_Bits
(J
) and Right_Bits
(J
);
2340 elsif Nkind
(N
) = N_Op_Or
then
2341 for J
in Left_Bits
'Range loop
2342 Left_Bits
(J
) := Left_Bits
(J
) or Right_Bits
(J
);
2346 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2348 for J
in Left_Bits
'Range loop
2349 Left_Bits
(J
) := Left_Bits
(J
) xor Right_Bits
(J
);
2353 Fold_Uint
(N
, From_Bits
(Left_Bits
, Etype
(N
)), Stat
);
2357 pragma Assert
(Is_Boolean_Type
(Etype
(N
)));
2359 if Nkind
(N
) = N_Op_And
then
2361 Test
(Is_True
(Left_Int
) and then Is_True
(Right_Int
)), Stat
);
2363 elsif Nkind
(N
) = N_Op_Or
then
2365 Test
(Is_True
(Left_Int
) or else Is_True
(Right_Int
)), Stat
);
2368 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2370 Test
(Is_True
(Left_Int
) xor Is_True
(Right_Int
)), Stat
);
2374 end Eval_Logical_Op
;
2376 ------------------------
2377 -- Eval_Membership_Op --
2378 ------------------------
2380 -- A membership test is potentially static if the expression is static, and
2381 -- the range is a potentially static range, or is a subtype mark denoting a
2382 -- static subtype (RM 4.9(12)).
2384 procedure Eval_Membership_Op
(N
: Node_Id
) is
2385 Left
: constant Node_Id
:= Left_Opnd
(N
);
2386 Right
: constant Node_Id
:= Right_Opnd
(N
);
2395 -- Ignore if error in either operand, except to make sure that Any_Type
2396 -- is properly propagated to avoid junk cascaded errors.
2398 if Etype
(Left
) = Any_Type
or else Etype
(Right
) = Any_Type
then
2399 Set_Etype
(N
, Any_Type
);
2403 -- Ignore if types involved have predicates
2405 if Present
(Predicate_Function
(Etype
(Left
)))
2407 Present
(Predicate_Function
(Etype
(Right
)))
2412 -- Case of right operand is a subtype name
2414 if Is_Entity_Name
(Right
) then
2415 Def_Id
:= Entity
(Right
);
2417 if (Is_Scalar_Type
(Def_Id
) or else Is_String_Type
(Def_Id
))
2418 and then Is_OK_Static_Subtype
(Def_Id
)
2420 Test_Expression_Is_Foldable
(N
, Left
, Stat
, Fold
);
2422 if not Fold
or else not Stat
then
2426 Check_Non_Static_Context
(Left
);
2430 -- For string membership tests we will check the length further on
2432 if not Is_String_Type
(Def_Id
) then
2433 Lo
:= Type_Low_Bound
(Def_Id
);
2434 Hi
:= Type_High_Bound
(Def_Id
);
2441 -- Case of right operand is a range
2444 if Is_Static_Range
(Right
) then
2445 Test_Expression_Is_Foldable
(N
, Left
, Stat
, Fold
);
2447 if not Fold
or else not Stat
then
2450 -- If one bound of range raises CE, then don't try to fold
2452 elsif not Is_OK_Static_Range
(Right
) then
2453 Check_Non_Static_Context
(Left
);
2458 Check_Non_Static_Context
(Left
);
2462 -- Here we know range is an OK static range
2464 Lo
:= Low_Bound
(Right
);
2465 Hi
:= High_Bound
(Right
);
2468 -- For strings we check that the length of the string expression is
2469 -- compatible with the string subtype if the subtype is constrained,
2470 -- or if unconstrained then the test is always true.
2472 if Is_String_Type
(Etype
(Right
)) then
2473 if not Is_Constrained
(Etype
(Right
)) then
2478 Typlen
: constant Uint
:= String_Type_Len
(Etype
(Right
));
2479 Strlen
: constant Uint
:=
2481 (String_Length
(Strval
(Get_String_Val
(Left
))));
2483 Result
:= (Typlen
= Strlen
);
2487 -- Fold the membership test. We know we have a static range and Lo and
2488 -- Hi are set to the expressions for the end points of this range.
2490 elsif Is_Real_Type
(Etype
(Right
)) then
2492 Leftval
: constant Ureal
:= Expr_Value_R
(Left
);
2495 Result
:= Expr_Value_R
(Lo
) <= Leftval
2496 and then Leftval
<= Expr_Value_R
(Hi
);
2501 Leftval
: constant Uint
:= Expr_Value
(Left
);
2504 Result
:= Expr_Value
(Lo
) <= Leftval
2505 and then Leftval
<= Expr_Value
(Hi
);
2509 if Nkind
(N
) = N_Not_In
then
2510 Result
:= not Result
;
2513 Fold_Uint
(N
, Test
(Result
), True);
2515 Warn_On_Known_Condition
(N
);
2516 end Eval_Membership_Op
;
2518 ------------------------
2519 -- Eval_Named_Integer --
2520 ------------------------
2522 procedure Eval_Named_Integer
(N
: Node_Id
) is
2525 Expr_Value
(Expression
(Declaration_Node
(Entity
(N
)))), True);
2526 end Eval_Named_Integer
;
2528 ---------------------
2529 -- Eval_Named_Real --
2530 ---------------------
2532 procedure Eval_Named_Real
(N
: Node_Id
) is
2535 Expr_Value_R
(Expression
(Declaration_Node
(Entity
(N
)))), True);
2536 end Eval_Named_Real
;
2542 -- Exponentiation is a static functions, so the result is potentially
2543 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2545 procedure Eval_Op_Expon
(N
: Node_Id
) is
2546 Left
: constant Node_Id
:= Left_Opnd
(N
);
2547 Right
: constant Node_Id
:= Right_Opnd
(N
);
2552 -- If not foldable we are done
2554 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2560 -- Fold exponentiation operation
2563 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2568 if Is_Integer_Type
(Etype
(Left
)) then
2570 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2574 -- Exponentiation of an integer raises Constraint_Error for a
2575 -- negative exponent (RM 4.5.6).
2577 if Right_Int
< 0 then
2578 Apply_Compile_Time_Constraint_Error
2579 (N
, "integer exponent negative",
2580 CE_Range_Check_Failed
,
2585 if OK_Bits
(N
, Num_Bits
(Left_Int
) * Right_Int
) then
2586 Result
:= Left_Int
** Right_Int
;
2591 if Is_Modular_Integer_Type
(Etype
(N
)) then
2592 Result
:= Result
mod Modulus
(Etype
(N
));
2595 Fold_Uint
(N
, Result
, Stat
);
2603 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
2606 -- Cannot have a zero base with a negative exponent
2608 if UR_Is_Zero
(Left_Real
) then
2610 if Right_Int
< 0 then
2611 Apply_Compile_Time_Constraint_Error
2612 (N
, "zero ** negative integer",
2613 CE_Range_Check_Failed
,
2617 Fold_Ureal
(N
, Ureal_0
, Stat
);
2621 Fold_Ureal
(N
, Left_Real
** Right_Int
, Stat
);
2632 -- The not operation is a static functions, so the result is potentially
2633 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
2635 procedure Eval_Op_Not
(N
: Node_Id
) is
2636 Right
: constant Node_Id
:= Right_Opnd
(N
);
2641 -- If not foldable we are done
2643 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
2649 -- Fold not operation
2652 Rint
: constant Uint
:= Expr_Value
(Right
);
2653 Typ
: constant Entity_Id
:= Etype
(N
);
2656 -- Negation is equivalent to subtracting from the modulus minus one.
2657 -- For a binary modulus this is equivalent to the ones-complement of
2658 -- the original value. For non-binary modulus this is an arbitrary
2659 -- but consistent definition.
2661 if Is_Modular_Integer_Type
(Typ
) then
2662 Fold_Uint
(N
, Modulus
(Typ
) - 1 - Rint
, Stat
);
2665 pragma Assert
(Is_Boolean_Type
(Typ
));
2666 Fold_Uint
(N
, Test
(not Is_True
(Rint
)), Stat
);
2669 Set_Is_Static_Expression
(N
, Stat
);
2673 -------------------------------
2674 -- Eval_Qualified_Expression --
2675 -------------------------------
2677 -- A qualified expression is potentially static if its subtype mark denotes
2678 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2680 procedure Eval_Qualified_Expression
(N
: Node_Id
) is
2681 Operand
: constant Node_Id
:= Expression
(N
);
2682 Target_Type
: constant Entity_Id
:= Entity
(Subtype_Mark
(N
));
2689 -- Can only fold if target is string or scalar and subtype is static.
2690 -- Also, do not fold if our parent is an allocator (this is because the
2691 -- qualified expression is really part of the syntactic structure of an
2692 -- allocator, and we do not want to end up with something that
2693 -- corresponds to "new 1" where the 1 is the result of folding a
2694 -- qualified expression).
2696 if not Is_Static_Subtype
(Target_Type
)
2697 or else Nkind
(Parent
(N
)) = N_Allocator
2699 Check_Non_Static_Context
(Operand
);
2701 -- If operand is known to raise constraint_error, set the flag on the
2702 -- expression so it does not get optimized away.
2704 if Nkind
(Operand
) = N_Raise_Constraint_Error
then
2705 Set_Raises_Constraint_Error
(N
);
2711 -- If not foldable we are done
2713 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
2718 -- Don't try fold if target type has constraint error bounds
2720 elsif not Is_OK_Static_Subtype
(Target_Type
) then
2721 Set_Raises_Constraint_Error
(N
);
2725 -- Here we will fold, save Print_In_Hex indication
2727 Hex
:= Nkind
(Operand
) = N_Integer_Literal
2728 and then Print_In_Hex
(Operand
);
2730 -- Fold the result of qualification
2732 if Is_Discrete_Type
(Target_Type
) then
2733 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
2735 -- Preserve Print_In_Hex indication
2737 if Hex
and then Nkind
(N
) = N_Integer_Literal
then
2738 Set_Print_In_Hex
(N
);
2741 elsif Is_Real_Type
(Target_Type
) then
2742 Fold_Ureal
(N
, Expr_Value_R
(Operand
), Stat
);
2745 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Stat
);
2748 Set_Is_Static_Expression
(N
, False);
2750 Check_String_Literal_Length
(N
, Target_Type
);
2756 -- The expression may be foldable but not static
2758 Set_Is_Static_Expression
(N
, Stat
);
2760 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
2763 end Eval_Qualified_Expression
;
2765 -----------------------
2766 -- Eval_Real_Literal --
2767 -----------------------
2769 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2770 -- as static by the analyzer. The reason we did it that early is to allow
2771 -- the possibility of turning off the Is_Static_Expression flag after
2772 -- analysis, but before resolution, when integer literals are generated
2773 -- in the expander that do not correspond to static expressions.
2775 procedure Eval_Real_Literal
(N
: Node_Id
) is
2776 PK
: constant Node_Kind
:= Nkind
(Parent
(N
));
2779 -- If the literal appears in a non-expression context and not as part of
2780 -- a number declaration, then it is appearing in a non-static context,
2783 if PK
not in N_Subexpr
and then PK
/= N_Number_Declaration
then
2784 Check_Non_Static_Context
(N
);
2786 end Eval_Real_Literal
;
2788 ------------------------
2789 -- Eval_Relational_Op --
2790 ------------------------
2792 -- Relational operations are static functions, so the result is static if
2793 -- both operands are static (RM 4.9(7), 4.9(20)), except that for strings,
2794 -- the result is never static, even if the operands are.
2796 procedure Eval_Relational_Op
(N
: Node_Id
) is
2797 Left
: constant Node_Id
:= Left_Opnd
(N
);
2798 Right
: constant Node_Id
:= Right_Opnd
(N
);
2799 Typ
: constant Entity_Id
:= Etype
(Left
);
2800 Otype
: Entity_Id
:= Empty
;
2804 -- One special case to deal with first. If we can tell that the result
2805 -- will be false because the lengths of one or more index subtypes are
2806 -- compile time known and different, then we can replace the entire
2807 -- result by False. We only do this for one dimensional arrays, because
2808 -- the case of multi-dimensional arrays is rare and too much trouble! If
2809 -- one of the operands is an illegal aggregate, its type might still be
2810 -- an arbitrary composite type, so nothing to do.
2812 if Is_Array_Type
(Typ
)
2813 and then Typ
/= Any_Composite
2814 and then Number_Dimensions
(Typ
) = 1
2815 and then (Nkind
(N
) = N_Op_Eq
or else Nkind
(N
) = N_Op_Ne
)
2817 if Raises_Constraint_Error
(Left
)
2818 or else Raises_Constraint_Error
(Right
)
2823 -- OK, we have the case where we may be able to do this fold
2825 Length_Mismatch
: declare
2826 procedure Get_Static_Length
(Op
: Node_Id
; Len
: out Uint
);
2827 -- If Op is an expression for a constrained array with a known at
2828 -- compile time length, then Len is set to this (non-negative
2829 -- length). Otherwise Len is set to minus 1.
2831 -----------------------
2832 -- Get_Static_Length --
2833 -----------------------
2835 procedure Get_Static_Length
(Op
: Node_Id
; Len
: out Uint
) is
2839 -- First easy case string literal
2841 if Nkind
(Op
) = N_String_Literal
then
2842 Len
:= UI_From_Int
(String_Length
(Strval
(Op
)));
2846 -- Second easy case, not constrained subtype, so no length
2848 if not Is_Constrained
(Etype
(Op
)) then
2849 Len
:= Uint_Minus_1
;
2855 T
:= Etype
(First_Index
(Etype
(Op
)));
2857 -- The simple case, both bounds are known at compile time
2859 if Is_Discrete_Type
(T
)
2861 Compile_Time_Known_Value
(Type_Low_Bound
(T
))
2863 Compile_Time_Known_Value
(Type_High_Bound
(T
))
2865 Len
:= UI_Max
(Uint_0
,
2866 Expr_Value
(Type_High_Bound
(T
)) -
2867 Expr_Value
(Type_Low_Bound
(T
)) + 1);
2871 -- A more complex case, where the bounds are of the form
2872 -- X [+/- K1] .. X [+/- K2]), where X is an expression that is
2873 -- either A'First or A'Last (with A an entity name), or X is an
2874 -- entity name, and the two X's are the same and K1 and K2 are
2875 -- known at compile time, in this case, the length can also be
2876 -- computed at compile time, even though the bounds are not
2877 -- known. A common case of this is e.g. (X'First .. X'First+5).
2879 Extract_Length
: declare
2880 procedure Decompose_Expr
2882 Ent
: out Entity_Id
;
2883 Kind
: out Character;
2885 -- Given an expression, see if is of the form above,
2886 -- X [+/- K]. If so Ent is set to the entity in X,
2887 -- Kind is 'F','L','E' for 'First/'Last/simple entity,
2888 -- and Cons is the value of K. If the expression is
2889 -- not of the required form, Ent is set to Empty.
2891 --------------------
2892 -- Decompose_Expr --
2893 --------------------
2895 procedure Decompose_Expr
2897 Ent
: out Entity_Id
;
2898 Kind
: out Character;
2904 if Nkind
(Expr
) = N_Op_Add
2905 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
2907 Exp
:= Left_Opnd
(Expr
);
2908 Cons
:= Expr_Value
(Right_Opnd
(Expr
));
2910 elsif Nkind
(Expr
) = N_Op_Subtract
2911 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
2913 Exp
:= Left_Opnd
(Expr
);
2914 Cons
:= -Expr_Value
(Right_Opnd
(Expr
));
2916 -- If the bound is a constant created to remove side
2917 -- effects, recover original expression to see if it has
2918 -- one of the recognizable forms.
2920 elsif Nkind
(Expr
) = N_Identifier
2921 and then not Comes_From_Source
(Entity
(Expr
))
2922 and then Ekind
(Entity
(Expr
)) = E_Constant
2924 Nkind
(Parent
(Entity
(Expr
))) = N_Object_Declaration
2926 Exp
:= Expression
(Parent
(Entity
(Expr
)));
2927 Decompose_Expr
(Exp
, Ent
, Kind
, Cons
);
2929 -- If original expression includes an entity, create a
2930 -- reference to it for use below.
2932 if Present
(Ent
) then
2933 Exp
:= New_Occurrence_Of
(Ent
, Sloc
(Ent
));
2941 -- At this stage Exp is set to the potential X
2943 if Nkind
(Exp
) = N_Attribute_Reference
then
2944 if Attribute_Name
(Exp
) = Name_First
then
2947 elsif Attribute_Name
(Exp
) = Name_Last
then
2955 Exp
:= Prefix
(Exp
);
2961 if Is_Entity_Name
(Exp
)
2962 and then Present
(Entity
(Exp
))
2964 Ent
:= Entity
(Exp
);
2972 Ent1
, Ent2
: Entity_Id
;
2973 Kind1
, Kind2
: Character;
2974 Cons1
, Cons2
: Uint
;
2976 -- Start of processing for Extract_Length
2980 (Original_Node
(Type_Low_Bound
(T
)), Ent1
, Kind1
, Cons1
);
2982 (Original_Node
(Type_High_Bound
(T
)), Ent2
, Kind2
, Cons2
);
2985 and then Kind1
= Kind2
2986 and then Ent1
= Ent2
2988 Len
:= Cons2
- Cons1
+ 1;
2990 Len
:= Uint_Minus_1
;
2993 end Get_Static_Length
;
3000 -- Start of processing for Length_Mismatch
3003 Get_Static_Length
(Left
, Len_L
);
3004 Get_Static_Length
(Right
, Len_R
);
3006 if Len_L
/= Uint_Minus_1
3007 and then Len_R
/= Uint_Minus_1
3008 and then Len_L
/= Len_R
3010 Fold_Uint
(N
, Test
(Nkind
(N
) = N_Op_Ne
), False);
3011 Warn_On_Known_Condition
(N
);
3014 end Length_Mismatch
;
3018 Is_Static_Expression
: Boolean;
3019 Is_Foldable
: Boolean;
3020 pragma Unreferenced
(Is_Foldable
);
3023 -- Initialize the value of Is_Static_Expression. The value of
3024 -- Is_Foldable returned by Test_Expression_Is_Foldable is not needed
3025 -- since, even when some operand is a variable, we can still perform
3026 -- the static evaluation of the expression in some cases (for
3027 -- example, for a variable of a subtype of Integer we statically
3028 -- know that any value stored in such variable is smaller than
3031 Test_Expression_Is_Foldable
3032 (N
, Left
, Right
, Is_Static_Expression
, Is_Foldable
);
3034 -- Only comparisons of scalars can give static results. In
3035 -- particular, comparisons of strings never yield a static
3036 -- result, even if both operands are static strings.
3038 if not Is_Scalar_Type
(Typ
) then
3039 Is_Static_Expression
:= False;
3040 Set_Is_Static_Expression
(N
, False);
3043 -- For operators on universal numeric types called as functions with
3044 -- an explicit scope, determine appropriate specific numeric type,
3045 -- and diagnose possible ambiguity.
3047 if Is_Universal_Numeric_Type
(Etype
(Left
))
3049 Is_Universal_Numeric_Type
(Etype
(Right
))
3051 Otype
:= Find_Universal_Operator_Type
(N
);
3054 -- For static real type expressions, we cannot use
3055 -- Compile_Time_Compare since it worries about run-time
3056 -- results which are not exact.
3058 if Is_Static_Expression
and then Is_Real_Type
(Typ
) then
3060 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
3061 Right_Real
: constant Ureal
:= Expr_Value_R
(Right
);
3065 when N_Op_Eq
=> Result
:= (Left_Real
= Right_Real
);
3066 when N_Op_Ne
=> Result
:= (Left_Real
/= Right_Real
);
3067 when N_Op_Lt
=> Result
:= (Left_Real
< Right_Real
);
3068 when N_Op_Le
=> Result
:= (Left_Real
<= Right_Real
);
3069 when N_Op_Gt
=> Result
:= (Left_Real
> Right_Real
);
3070 when N_Op_Ge
=> Result
:= (Left_Real
>= Right_Real
);
3073 raise Program_Error
;
3076 Fold_Uint
(N
, Test
(Result
), True);
3079 -- For all other cases, we use Compile_Time_Compare to do the compare
3083 CR
: constant Compare_Result
:=
3084 Compile_Time_Compare
3085 (Left
, Right
, Assume_Valid
=> False);
3088 if CR
= Unknown
then
3096 elsif CR
= NE
or else CR
= GT
or else CR
= LT
then
3103 if CR
= NE
or else CR
= GT
or else CR
= LT
then
3114 elsif CR
= EQ
or else CR
= GT
or else CR
= GE
then
3121 if CR
= LT
or else CR
= EQ
or else CR
= LE
then
3132 elsif CR
= EQ
or else CR
= LT
or else CR
= LE
then
3139 if CR
= GT
or else CR
= EQ
or else CR
= GE
then
3148 raise Program_Error
;
3152 Fold_Uint
(N
, Test
(Result
), Is_Static_Expression
);
3156 -- For the case of a folded relational operator on a specific numeric
3157 -- type, freeze operand type now.
3159 if Present
(Otype
) then
3160 Freeze_Before
(N
, Otype
);
3163 Warn_On_Known_Condition
(N
);
3164 end Eval_Relational_Op
;
3170 -- Shift operations are intrinsic operations that can never be static, so
3171 -- the only processing required is to perform the required check for a non
3172 -- static context for the two operands.
3174 -- Actually we could do some compile time evaluation here some time ???
3176 procedure Eval_Shift
(N
: Node_Id
) is
3178 Check_Non_Static_Context
(Left_Opnd
(N
));
3179 Check_Non_Static_Context
(Right_Opnd
(N
));
3182 ------------------------
3183 -- Eval_Short_Circuit --
3184 ------------------------
3186 -- A short circuit operation is potentially static if both operands are
3187 -- potentially static (RM 4.9 (13)).
3189 procedure Eval_Short_Circuit
(N
: Node_Id
) is
3190 Kind
: constant Node_Kind
:= Nkind
(N
);
3191 Left
: constant Node_Id
:= Left_Opnd
(N
);
3192 Right
: constant Node_Id
:= Right_Opnd
(N
);
3195 Rstat
: constant Boolean :=
3196 Is_Static_Expression
(Left
)
3198 Is_Static_Expression
(Right
);
3201 -- Short circuit operations are never static in Ada 83
3203 if Ada_Version
= Ada_83
and then Comes_From_Source
(N
) then
3204 Check_Non_Static_Context
(Left
);
3205 Check_Non_Static_Context
(Right
);
3209 -- Now look at the operands, we can't quite use the normal call to
3210 -- Test_Expression_Is_Foldable here because short circuit operations
3211 -- are a special case, they can still be foldable, even if the right
3212 -- operand raises constraint error.
3214 -- If either operand is Any_Type, just propagate to result and do not
3215 -- try to fold, this prevents cascaded errors.
3217 if Etype
(Left
) = Any_Type
or else Etype
(Right
) = Any_Type
then
3218 Set_Etype
(N
, Any_Type
);
3221 -- If left operand raises constraint error, then replace node N with
3222 -- the raise constraint error node, and we are obviously not foldable.
3223 -- Is_Static_Expression is set from the two operands in the normal way,
3224 -- and we check the right operand if it is in a non-static context.
3226 elsif Raises_Constraint_Error
(Left
) then
3228 Check_Non_Static_Context
(Right
);
3231 Rewrite_In_Raise_CE
(N
, Left
);
3232 Set_Is_Static_Expression
(N
, Rstat
);
3235 -- If the result is not static, then we won't in any case fold
3237 elsif not Rstat
then
3238 Check_Non_Static_Context
(Left
);
3239 Check_Non_Static_Context
(Right
);
3243 -- Here the result is static, note that, unlike the normal processing
3244 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
3245 -- the right operand raises constraint error, that's because it is not
3246 -- significant if the left operand is decisive.
3248 Set_Is_Static_Expression
(N
);
3250 -- It does not matter if the right operand raises constraint error if
3251 -- it will not be evaluated. So deal specially with the cases where
3252 -- the right operand is not evaluated. Note that we will fold these
3253 -- cases even if the right operand is non-static, which is fine, but
3254 -- of course in these cases the result is not potentially static.
3256 Left_Int
:= Expr_Value
(Left
);
3258 if (Kind
= N_And_Then
and then Is_False
(Left_Int
))
3260 (Kind
= N_Or_Else
and then Is_True
(Left_Int
))
3262 Fold_Uint
(N
, Left_Int
, Rstat
);
3266 -- If first operand not decisive, then it does matter if the right
3267 -- operand raises constraint error, since it will be evaluated, so
3268 -- we simply replace the node with the right operand. Note that this
3269 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
3270 -- (both are set to True in Right).
3272 if Raises_Constraint_Error
(Right
) then
3273 Rewrite_In_Raise_CE
(N
, Right
);
3274 Check_Non_Static_Context
(Left
);
3278 -- Otherwise the result depends on the right operand
3280 Fold_Uint
(N
, Expr_Value
(Right
), Rstat
);
3282 end Eval_Short_Circuit
;
3288 -- Slices can never be static, so the only processing required is to check
3289 -- for non-static context if an explicit range is given.
3291 procedure Eval_Slice
(N
: Node_Id
) is
3292 Drange
: constant Node_Id
:= Discrete_Range
(N
);
3294 if Nkind
(Drange
) = N_Range
then
3295 Check_Non_Static_Context
(Low_Bound
(Drange
));
3296 Check_Non_Static_Context
(High_Bound
(Drange
));
3299 -- A slice of the form A (subtype), when the subtype is the index of
3300 -- the type of A, is redundant, the slice can be replaced with A, and
3301 -- this is worth a warning.
3303 if Is_Entity_Name
(Prefix
(N
)) then
3305 E
: constant Entity_Id
:= Entity
(Prefix
(N
));
3306 T
: constant Entity_Id
:= Etype
(E
);
3308 if Ekind
(E
) = E_Constant
3309 and then Is_Array_Type
(T
)
3310 and then Is_Entity_Name
(Drange
)
3312 if Is_Entity_Name
(Original_Node
(First_Index
(T
)))
3313 and then Entity
(Original_Node
(First_Index
(T
)))
3316 if Warn_On_Redundant_Constructs
then
3317 Error_Msg_N
("redundant slice denotes whole array?r?", N
);
3320 -- The following might be a useful optimization???
3322 -- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
3329 ---------------------------------
3330 -- Eval_Static_Predicate_Check --
3331 ---------------------------------
3333 function Eval_Static_Predicate_Check
3335 Typ
: Entity_Id
) return Boolean
3337 Loc
: constant Source_Ptr
:= Sloc
(N
);
3338 Pred
: constant List_Id
:= Static_Predicate
(Typ
);
3346 -- The static predicate is a list of alternatives in the proper format
3347 -- for an Ada 2012 membership test. If the argument is a literal, the
3348 -- membership test can be evaluated statically. The caller transforms
3349 -- a result of False into a static contraint error.
3351 Test
:= Make_In
(Loc
,
3352 Left_Opnd
=> New_Copy_Tree
(N
),
3353 Right_Opnd
=> Empty
,
3354 Alternatives
=> Pred
);
3355 Analyze_And_Resolve
(Test
, Standard_Boolean
);
3357 return Nkind
(Test
) = N_Identifier
3358 and then Entity
(Test
) = Standard_True
;
3359 end Eval_Static_Predicate_Check
;
3361 -------------------------
3362 -- Eval_String_Literal --
3363 -------------------------
3365 procedure Eval_String_Literal
(N
: Node_Id
) is
3366 Typ
: constant Entity_Id
:= Etype
(N
);
3367 Bas
: constant Entity_Id
:= Base_Type
(Typ
);
3373 -- Nothing to do if error type (handles cases like default expressions
3374 -- or generics where we have not yet fully resolved the type).
3376 if Bas
= Any_Type
or else Bas
= Any_String
then
3380 -- String literals are static if the subtype is static (RM 4.9(2)), so
3381 -- reset the static expression flag (it was set unconditionally in
3382 -- Analyze_String_Literal) if the subtype is non-static. We tell if
3383 -- the subtype is static by looking at the lower bound.
3385 if Ekind
(Typ
) = E_String_Literal_Subtype
then
3386 if not Is_OK_Static_Expression
(String_Literal_Low_Bound
(Typ
)) then
3387 Set_Is_Static_Expression
(N
, False);
3391 -- Here if Etype of string literal is normal Etype (not yet possible,
3392 -- but may be possible in future).
3394 elsif not Is_OK_Static_Expression
3395 (Type_Low_Bound
(Etype
(First_Index
(Typ
))))
3397 Set_Is_Static_Expression
(N
, False);
3401 -- If original node was a type conversion, then result if non-static
3403 if Nkind
(Original_Node
(N
)) = N_Type_Conversion
then
3404 Set_Is_Static_Expression
(N
, False);
3408 -- Test for illegal Ada 95 cases. A string literal is illegal in Ada 95
3409 -- if its bounds are outside the index base type and this index type is
3410 -- static. This can happen in only two ways. Either the string literal
3411 -- is too long, or it is null, and the lower bound is type'First. In
3412 -- either case it is the upper bound that is out of range of the index
3415 if Ada_Version
>= Ada_95
then
3416 if Root_Type
(Bas
) = Standard_String
3418 Root_Type
(Bas
) = Standard_Wide_String
3420 Xtp
:= Standard_Positive
;
3422 Xtp
:= Etype
(First_Index
(Bas
));
3425 if Ekind
(Typ
) = E_String_Literal_Subtype
then
3426 Lo
:= String_Literal_Low_Bound
(Typ
);
3428 Lo
:= Type_Low_Bound
(Etype
(First_Index
(Typ
)));
3431 Len
:= String_Length
(Strval
(N
));
3433 if UI_From_Int
(Len
) > String_Type_Len
(Bas
) then
3434 Apply_Compile_Time_Constraint_Error
3435 (N
, "string literal too long for}", CE_Length_Check_Failed
,
3437 Typ
=> First_Subtype
(Bas
));
3440 and then not Is_Generic_Type
(Xtp
)
3442 Expr_Value
(Lo
) = Expr_Value
(Type_Low_Bound
(Base_Type
(Xtp
)))
3444 Apply_Compile_Time_Constraint_Error
3445 (N
, "null string literal not allowed for}",
3446 CE_Length_Check_Failed
,
3448 Typ
=> First_Subtype
(Bas
));
3451 end Eval_String_Literal
;
3453 --------------------------
3454 -- Eval_Type_Conversion --
3455 --------------------------
3457 -- A type conversion is potentially static if its subtype mark is for a
3458 -- static scalar subtype, and its operand expression is potentially static
3461 procedure Eval_Type_Conversion
(N
: Node_Id
) is
3462 Operand
: constant Node_Id
:= Expression
(N
);
3463 Source_Type
: constant Entity_Id
:= Etype
(Operand
);
3464 Target_Type
: constant Entity_Id
:= Etype
(N
);
3469 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean;
3470 -- Returns true if type T is an integer type, or if it is a fixed-point
3471 -- type to be treated as an integer (i.e. the flag Conversion_OK is set
3472 -- on the conversion node).
3474 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean;
3475 -- Returns true if type T is a floating-point type, or if it is a
3476 -- fixed-point type that is not to be treated as an integer (i.e. the
3477 -- flag Conversion_OK is not set on the conversion node).
3479 ------------------------------
3480 -- To_Be_Treated_As_Integer --
3481 ------------------------------
3483 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean is
3487 or else (Is_Fixed_Point_Type
(T
) and then Conversion_OK
(N
));
3488 end To_Be_Treated_As_Integer
;
3490 ---------------------------
3491 -- To_Be_Treated_As_Real --
3492 ---------------------------
3494 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean is
3497 Is_Floating_Point_Type
(T
)
3498 or else (Is_Fixed_Point_Type
(T
) and then not Conversion_OK
(N
));
3499 end To_Be_Treated_As_Real
;
3501 -- Start of processing for Eval_Type_Conversion
3504 -- Cannot fold if target type is non-static or if semantic error
3506 if not Is_Static_Subtype
(Target_Type
) then
3507 Check_Non_Static_Context
(Operand
);
3510 elsif Error_Posted
(N
) then
3514 -- If not foldable we are done
3516 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
3521 -- Don't try fold if target type has constraint error bounds
3523 elsif not Is_OK_Static_Subtype
(Target_Type
) then
3524 Set_Raises_Constraint_Error
(N
);
3528 -- Remaining processing depends on operand types. Note that in the
3529 -- following type test, fixed-point counts as real unless the flag
3530 -- Conversion_OK is set, in which case it counts as integer.
3532 -- Fold conversion, case of string type. The result is not static
3534 if Is_String_Type
(Target_Type
) then
3535 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Static
=> False);
3539 -- Fold conversion, case of integer target type
3541 elsif To_Be_Treated_As_Integer
(Target_Type
) then
3546 -- Integer to integer conversion
3548 if To_Be_Treated_As_Integer
(Source_Type
) then
3549 Result
:= Expr_Value
(Operand
);
3551 -- Real to integer conversion
3554 Result
:= UR_To_Uint
(Expr_Value_R
(Operand
));
3557 -- If fixed-point type (Conversion_OK must be set), then the
3558 -- result is logically an integer, but we must replace the
3559 -- conversion with the corresponding real literal, since the
3560 -- type from a semantic point of view is still fixed-point.
3562 if Is_Fixed_Point_Type
(Target_Type
) then
3564 (N
, UR_From_Uint
(Result
) * Small_Value
(Target_Type
), Stat
);
3566 -- Otherwise result is integer literal
3569 Fold_Uint
(N
, Result
, Stat
);
3573 -- Fold conversion, case of real target type
3575 elsif To_Be_Treated_As_Real
(Target_Type
) then
3580 if To_Be_Treated_As_Real
(Source_Type
) then
3581 Result
:= Expr_Value_R
(Operand
);
3583 Result
:= UR_From_Uint
(Expr_Value
(Operand
));
3586 Fold_Ureal
(N
, Result
, Stat
);
3589 -- Enumeration types
3592 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
3595 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
3599 end Eval_Type_Conversion
;
3605 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
3606 -- are potentially static if the operand is potentially static (RM 4.9(7)).
3608 procedure Eval_Unary_Op
(N
: Node_Id
) is
3609 Right
: constant Node_Id
:= Right_Opnd
(N
);
3610 Otype
: Entity_Id
:= Empty
;
3615 -- If not foldable we are done
3617 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
3623 if Etype
(Right
) = Universal_Integer
3625 Etype
(Right
) = Universal_Real
3627 Otype
:= Find_Universal_Operator_Type
(N
);
3630 -- Fold for integer case
3632 if Is_Integer_Type
(Etype
(N
)) then
3634 Rint
: constant Uint
:= Expr_Value
(Right
);
3638 -- In the case of modular unary plus and abs there is no need
3639 -- to adjust the result of the operation since if the original
3640 -- operand was in bounds the result will be in the bounds of the
3641 -- modular type. However, in the case of modular unary minus the
3642 -- result may go out of the bounds of the modular type and needs
3645 if Nkind
(N
) = N_Op_Plus
then
3648 elsif Nkind
(N
) = N_Op_Minus
then
3649 if Is_Modular_Integer_Type
(Etype
(N
)) then
3650 Result
:= (-Rint
) mod Modulus
(Etype
(N
));
3656 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
3660 Fold_Uint
(N
, Result
, Stat
);
3663 -- Fold for real case
3665 elsif Is_Real_Type
(Etype
(N
)) then
3667 Rreal
: constant Ureal
:= Expr_Value_R
(Right
);
3671 if Nkind
(N
) = N_Op_Plus
then
3674 elsif Nkind
(N
) = N_Op_Minus
then
3675 Result
:= UR_Negate
(Rreal
);
3678 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
3679 Result
:= abs Rreal
;
3682 Fold_Ureal
(N
, Result
, Stat
);
3686 -- If the operator was resolved to a specific type, make sure that type
3687 -- is frozen even if the expression is folded into a literal (which has
3688 -- a universal type).
3690 if Present
(Otype
) then
3691 Freeze_Before
(N
, Otype
);
3695 -------------------------------
3696 -- Eval_Unchecked_Conversion --
3697 -------------------------------
3699 -- Unchecked conversions can never be static, so the only required
3700 -- processing is to check for a non-static context for the operand.
3702 procedure Eval_Unchecked_Conversion
(N
: Node_Id
) is
3704 Check_Non_Static_Context
(Expression
(N
));
3705 end Eval_Unchecked_Conversion
;
3707 --------------------
3708 -- Expr_Rep_Value --
3709 --------------------
3711 function Expr_Rep_Value
(N
: Node_Id
) return Uint
is
3712 Kind
: constant Node_Kind
:= Nkind
(N
);
3716 if Is_Entity_Name
(N
) then
3719 -- An enumeration literal that was either in the source or created
3720 -- as a result of static evaluation.
3722 if Ekind
(Ent
) = E_Enumeration_Literal
then
3723 return Enumeration_Rep
(Ent
);
3725 -- A user defined static constant
3728 pragma Assert
(Ekind
(Ent
) = E_Constant
);
3729 return Expr_Rep_Value
(Constant_Value
(Ent
));
3732 -- An integer literal that was either in the source or created as a
3733 -- result of static evaluation.
3735 elsif Kind
= N_Integer_Literal
then
3738 -- A real literal for a fixed-point type. This must be the fixed-point
3739 -- case, either the literal is of a fixed-point type, or it is a bound
3740 -- of a fixed-point type, with type universal real. In either case we
3741 -- obtain the desired value from Corresponding_Integer_Value.
3743 elsif Kind
= N_Real_Literal
then
3744 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
3745 return Corresponding_Integer_Value
(N
);
3747 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3749 elsif Kind
= N_Attribute_Reference
3750 and then Attribute_Name
(N
) = Name_Null_Parameter
3754 -- Otherwise must be character literal
3757 pragma Assert
(Kind
= N_Character_Literal
);
3760 -- Since Character literals of type Standard.Character don't have any
3761 -- defining character literals built for them, they do not have their
3762 -- Entity set, so just use their Char code. Otherwise for user-
3763 -- defined character literals use their Pos value as usual which is
3764 -- the same as the Rep value.
3767 return Char_Literal_Value
(N
);
3769 return Enumeration_Rep
(Ent
);
3778 function Expr_Value
(N
: Node_Id
) return Uint
is
3779 Kind
: constant Node_Kind
:= Nkind
(N
);
3780 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(N
) mod CV_Cache_Size
);
3785 -- If already in cache, then we know it's compile time known and we can
3786 -- return the value that was previously stored in the cache since
3787 -- compile time known values cannot change.
3789 if CV_Ent
.N
= N
then
3793 -- Otherwise proceed to test value
3795 if Is_Entity_Name
(N
) then
3798 -- An enumeration literal that was either in the source or created as
3799 -- a result of static evaluation.
3801 if Ekind
(Ent
) = E_Enumeration_Literal
then
3802 Val
:= Enumeration_Pos
(Ent
);
3804 -- A user defined static constant
3807 pragma Assert
(Ekind
(Ent
) = E_Constant
);
3808 Val
:= Expr_Value
(Constant_Value
(Ent
));
3811 -- An integer literal that was either in the source or created as a
3812 -- result of static evaluation.
3814 elsif Kind
= N_Integer_Literal
then
3817 -- A real literal for a fixed-point type. This must be the fixed-point
3818 -- case, either the literal is of a fixed-point type, or it is a bound
3819 -- of a fixed-point type, with type universal real. In either case we
3820 -- obtain the desired value from Corresponding_Integer_Value.
3822 elsif Kind
= N_Real_Literal
then
3824 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
3825 Val
:= Corresponding_Integer_Value
(N
);
3827 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3829 elsif Kind
= N_Attribute_Reference
3830 and then Attribute_Name
(N
) = Name_Null_Parameter
3834 -- Otherwise must be character literal
3837 pragma Assert
(Kind
= N_Character_Literal
);
3840 -- Since Character literals of type Standard.Character don't
3841 -- have any defining character literals built for them, they
3842 -- do not have their Entity set, so just use their Char
3843 -- code. Otherwise for user-defined character literals use
3844 -- their Pos value as usual.
3847 Val
:= Char_Literal_Value
(N
);
3849 Val
:= Enumeration_Pos
(Ent
);
3853 -- Come here with Val set to value to be returned, set cache
3864 function Expr_Value_E
(N
: Node_Id
) return Entity_Id
is
3865 Ent
: constant Entity_Id
:= Entity
(N
);
3868 if Ekind
(Ent
) = E_Enumeration_Literal
then
3871 pragma Assert
(Ekind
(Ent
) = E_Constant
);
3872 return Expr_Value_E
(Constant_Value
(Ent
));
3880 function Expr_Value_R
(N
: Node_Id
) return Ureal
is
3881 Kind
: constant Node_Kind
:= Nkind
(N
);
3885 if Kind
= N_Real_Literal
then
3888 elsif Kind
= N_Identifier
or else Kind
= N_Expanded_Name
then
3890 pragma Assert
(Ekind
(Ent
) = E_Constant
);
3891 return Expr_Value_R
(Constant_Value
(Ent
));
3893 elsif Kind
= N_Integer_Literal
then
3894 return UR_From_Uint
(Expr_Value
(N
));
3896 -- Peculiar VMS case, if we have xxx'Null_Parameter, return 0.0
3898 elsif Kind
= N_Attribute_Reference
3899 and then Attribute_Name
(N
) = Name_Null_Parameter
3904 -- If we fall through, we have a node that cannot be interpreted as a
3905 -- compile time constant. That is definitely an error.
3907 raise Program_Error
;
3914 function Expr_Value_S
(N
: Node_Id
) return Node_Id
is
3916 if Nkind
(N
) = N_String_Literal
then
3919 pragma Assert
(Ekind
(Entity
(N
)) = E_Constant
);
3920 return Expr_Value_S
(Constant_Value
(Entity
(N
)));
3924 ----------------------------------
3925 -- Find_Universal_Operator_Type --
3926 ----------------------------------
3928 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
is
3929 PN
: constant Node_Id
:= Parent
(N
);
3930 Call
: constant Node_Id
:= Original_Node
(N
);
3931 Is_Int
: constant Boolean := Is_Integer_Type
(Etype
(N
));
3933 Is_Fix
: constant Boolean :=
3934 Nkind
(N
) in N_Binary_Op
3935 and then Nkind
(Right_Opnd
(N
)) /= Nkind
(Left_Opnd
(N
));
3936 -- A mixed-mode operation in this context indicates the presence of
3937 -- fixed-point type in the designated package.
3939 Is_Relational
: constant Boolean := Etype
(N
) = Standard_Boolean
;
3940 -- Case where N is a relational (or membership) operator (else it is an
3943 In_Membership
: constant Boolean :=
3944 Nkind
(PN
) in N_Membership_Test
3946 Nkind
(Right_Opnd
(PN
)) = N_Range
3948 Is_Universal_Numeric_Type
(Etype
(Left_Opnd
(PN
)))
3950 Is_Universal_Numeric_Type
3951 (Etype
(Low_Bound
(Right_Opnd
(PN
))))
3953 Is_Universal_Numeric_Type
3954 (Etype
(High_Bound
(Right_Opnd
(PN
))));
3955 -- Case where N is part of a membership test with a universal range
3959 Typ1
: Entity_Id
:= Empty
;
3962 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean;
3963 -- Check whether one operand is a mixed-mode operation that requires the
3964 -- presence of a fixed-point type. Given that all operands are universal
3965 -- and have been constant-folded, retrieve the original function call.
3967 ---------------------------
3968 -- Is_Mixed_Mode_Operand --
3969 ---------------------------
3971 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean is
3972 Onod
: constant Node_Id
:= Original_Node
(Op
);
3974 return Nkind
(Onod
) = N_Function_Call
3975 and then Present
(Next_Actual
(First_Actual
(Onod
)))
3976 and then Etype
(First_Actual
(Onod
)) /=
3977 Etype
(Next_Actual
(First_Actual
(Onod
)));
3978 end Is_Mixed_Mode_Operand
;
3980 -- Start of processing for Find_Universal_Operator_Type
3983 if Nkind
(Call
) /= N_Function_Call
3984 or else Nkind
(Name
(Call
)) /= N_Expanded_Name
3988 -- There are several cases where the context does not imply the type of
3990 -- - the universal expression appears in a type conversion;
3991 -- - the expression is a relational operator applied to universal
3993 -- - the expression is a membership test with a universal operand
3994 -- and a range with universal bounds.
3996 elsif Nkind
(Parent
(N
)) = N_Type_Conversion
3997 or else Is_Relational
3998 or else In_Membership
4000 Pack
:= Entity
(Prefix
(Name
(Call
)));
4002 -- If the prefix is a package declared elsewhere, iterate over its
4003 -- visible entities, otherwise iterate over all declarations in the
4004 -- designated scope.
4006 if Ekind
(Pack
) = E_Package
4007 and then not In_Open_Scopes
(Pack
)
4009 Priv_E
:= First_Private_Entity
(Pack
);
4015 E
:= First_Entity
(Pack
);
4016 while Present
(E
) and then E
/= Priv_E
loop
4017 if Is_Numeric_Type
(E
)
4018 and then Nkind
(Parent
(E
)) /= N_Subtype_Declaration
4019 and then Comes_From_Source
(E
)
4020 and then Is_Integer_Type
(E
) = Is_Int
4022 (Nkind
(N
) in N_Unary_Op
4023 or else Is_Relational
4024 or else Is_Fixed_Point_Type
(E
) = Is_Fix
)
4029 -- Before emitting an error, check for the presence of a
4030 -- mixed-mode operation that specifies a fixed point type.
4034 (Is_Mixed_Mode_Operand
(Left_Opnd
(N
))
4035 or else Is_Mixed_Mode_Operand
(Right_Opnd
(N
)))
4036 and then Is_Fixed_Point_Type
(E
) /= Is_Fixed_Point_Type
(Typ1
)
4039 if Is_Fixed_Point_Type
(E
) then
4044 -- More than one type of the proper class declared in P
4046 Error_Msg_N
("ambiguous operation", N
);
4047 Error_Msg_Sloc
:= Sloc
(Typ1
);
4048 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4049 Error_Msg_Sloc
:= Sloc
(E
);
4050 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4060 end Find_Universal_Operator_Type
;
4062 --------------------------
4063 -- Flag_Non_Static_Expr --
4064 --------------------------
4066 procedure Flag_Non_Static_Expr
(Msg
: String; Expr
: Node_Id
) is
4068 if Error_Posted
(Expr
) and then not All_Errors_Mode
then
4071 Error_Msg_F
(Msg
, Expr
);
4072 Why_Not_Static
(Expr
);
4074 end Flag_Non_Static_Expr
;
4080 procedure Fold_Str
(N
: Node_Id
; Val
: String_Id
; Static
: Boolean) is
4081 Loc
: constant Source_Ptr
:= Sloc
(N
);
4082 Typ
: constant Entity_Id
:= Etype
(N
);
4085 Rewrite
(N
, Make_String_Literal
(Loc
, Strval
=> Val
));
4087 -- We now have the literal with the right value, both the actual type
4088 -- and the expected type of this literal are taken from the expression
4089 -- that was evaluated. So now we do the Analyze and Resolve.
4091 -- Note that we have to reset Is_Static_Expression both after the
4092 -- analyze step (because Resolve will evaluate the literal, which
4093 -- will cause semantic errors if it is marked as static), and after
4094 -- the Resolve step (since Resolve in some cases sets this flag).
4097 Set_Is_Static_Expression
(N
, Static
);
4100 Set_Is_Static_Expression
(N
, Static
);
4107 procedure Fold_Uint
(N
: Node_Id
; Val
: Uint
; Static
: Boolean) is
4108 Loc
: constant Source_Ptr
:= Sloc
(N
);
4109 Typ
: Entity_Id
:= Etype
(N
);
4113 -- If we are folding a named number, retain the entity in the literal,
4116 if Is_Entity_Name
(N
)
4117 and then Ekind
(Entity
(N
)) = E_Named_Integer
4124 if Is_Private_Type
(Typ
) then
4125 Typ
:= Full_View
(Typ
);
4128 -- For a result of type integer, substitute an N_Integer_Literal node
4129 -- for the result of the compile time evaluation of the expression.
4130 -- For ASIS use, set a link to the original named number when not in
4131 -- a generic context.
4133 if Is_Integer_Type
(Typ
) then
4134 Rewrite
(N
, Make_Integer_Literal
(Loc
, Val
));
4136 Set_Original_Entity
(N
, Ent
);
4138 -- Otherwise we have an enumeration type, and we substitute either
4139 -- an N_Identifier or N_Character_Literal to represent the enumeration
4140 -- literal corresponding to the given value, which must always be in
4141 -- range, because appropriate tests have already been made for this.
4143 else pragma Assert
(Is_Enumeration_Type
(Typ
));
4144 Rewrite
(N
, Get_Enum_Lit_From_Pos
(Etype
(N
), Val
, Loc
));
4147 -- We now have the literal with the right value, both the actual type
4148 -- and the expected type of this literal are taken from the expression
4149 -- that was evaluated. So now we do the Analyze and Resolve.
4151 -- Note that we have to reset Is_Static_Expression both after the
4152 -- analyze step (because Resolve will evaluate the literal, which
4153 -- will cause semantic errors if it is marked as static), and after
4154 -- the Resolve step (since Resolve in some cases sets this flag).
4157 Set_Is_Static_Expression
(N
, Static
);
4160 Set_Is_Static_Expression
(N
, Static
);
4167 procedure Fold_Ureal
(N
: Node_Id
; Val
: Ureal
; Static
: Boolean) is
4168 Loc
: constant Source_Ptr
:= Sloc
(N
);
4169 Typ
: constant Entity_Id
:= Etype
(N
);
4173 -- If we are folding a named number, retain the entity in the literal,
4176 if Is_Entity_Name
(N
)
4177 and then Ekind
(Entity
(N
)) = E_Named_Real
4184 Rewrite
(N
, Make_Real_Literal
(Loc
, Realval
=> Val
));
4186 -- Set link to original named number, for ASIS use
4188 Set_Original_Entity
(N
, Ent
);
4190 -- We now have the literal with the right value, both the actual type
4191 -- and the expected type of this literal are taken from the expression
4192 -- that was evaluated. So now we do the Analyze and Resolve.
4194 -- Note that we have to reset Is_Static_Expression both after the
4195 -- analyze step (because Resolve will evaluate the literal, which
4196 -- will cause semantic errors if it is marked as static), and after
4197 -- the Resolve step (since Resolve in some cases sets this flag).
4200 Set_Is_Static_Expression
(N
, Static
);
4203 Set_Is_Static_Expression
(N
, Static
);
4210 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
is
4214 for J
in 0 .. B
'Last loop
4220 if Non_Binary_Modulus
(T
) then
4221 V
:= V
mod Modulus
(T
);
4227 --------------------
4228 -- Get_String_Val --
4229 --------------------
4231 function Get_String_Val
(N
: Node_Id
) return Node_Id
is
4233 if Nkind
(N
) = N_String_Literal
then
4236 elsif Nkind
(N
) = N_Character_Literal
then
4240 pragma Assert
(Is_Entity_Name
(N
));
4241 return Get_String_Val
(Constant_Value
(Entity
(N
)));
4249 procedure Initialize
is
4251 CV_Cache
:= (others => (Node_High_Bound
, Uint_0
));
4254 --------------------
4255 -- In_Subrange_Of --
4256 --------------------
4258 function In_Subrange_Of
4261 Fixed_Int
: Boolean := False) return Boolean
4270 if T1
= T2
or else Is_Subtype_Of
(T1
, T2
) then
4273 -- Never in range if both types are not scalar. Don't know if this can
4274 -- actually happen, but just in case.
4276 elsif not Is_Scalar_Type
(T1
) or else not Is_Scalar_Type
(T2
) then
4279 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
4280 -- definitely not compatible with T2.
4282 elsif Is_Floating_Point_Type
(T1
)
4283 and then Has_Infinities
(T1
)
4284 and then Is_Floating_Point_Type
(T2
)
4285 and then not Has_Infinities
(T2
)
4290 L1
:= Type_Low_Bound
(T1
);
4291 H1
:= Type_High_Bound
(T1
);
4293 L2
:= Type_Low_Bound
(T2
);
4294 H2
:= Type_High_Bound
(T2
);
4296 -- Check bounds to see if comparison possible at compile time
4298 if Compile_Time_Compare
(L1
, L2
, Assume_Valid
=> True) in Compare_GE
4300 Compile_Time_Compare
(H1
, H2
, Assume_Valid
=> True) in Compare_LE
4305 -- If bounds not comparable at compile time, then the bounds of T2
4306 -- must be compile time known or we cannot answer the query.
4308 if not Compile_Time_Known_Value
(L2
)
4309 or else not Compile_Time_Known_Value
(H2
)
4314 -- If the bounds of T1 are know at compile time then use these
4315 -- ones, otherwise use the bounds of the base type (which are of
4316 -- course always static).
4318 if not Compile_Time_Known_Value
(L1
) then
4319 L1
:= Type_Low_Bound
(Base_Type
(T1
));
4322 if not Compile_Time_Known_Value
(H1
) then
4323 H1
:= Type_High_Bound
(Base_Type
(T1
));
4326 -- Fixed point types should be considered as such only if
4327 -- flag Fixed_Int is set to False.
4329 if Is_Floating_Point_Type
(T1
) or else Is_Floating_Point_Type
(T2
)
4330 or else (Is_Fixed_Point_Type
(T1
) and then not Fixed_Int
)
4331 or else (Is_Fixed_Point_Type
(T2
) and then not Fixed_Int
)
4334 Expr_Value_R
(L2
) <= Expr_Value_R
(L1
)
4336 Expr_Value_R
(H2
) >= Expr_Value_R
(H1
);
4340 Expr_Value
(L2
) <= Expr_Value
(L1
)
4342 Expr_Value
(H2
) >= Expr_Value
(H1
);
4347 -- If any exception occurs, it means that we have some bug in the compiler
4348 -- possibly triggered by a previous error, or by some unforeseen peculiar
4349 -- occurrence. However, this is only an optimization attempt, so there is
4350 -- really no point in crashing the compiler. Instead we just decide, too
4351 -- bad, we can't figure out the answer in this case after all.
4356 -- Debug flag K disables this behavior (useful for debugging)
4358 if Debug_Flag_K
then
4369 function Is_In_Range
4372 Assume_Valid
: Boolean := False;
4373 Fixed_Int
: Boolean := False;
4374 Int_Real
: Boolean := False) return Boolean
4377 return Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
)
4385 function Is_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
4386 Typ
: constant Entity_Id
:= Etype
(Lo
);
4389 if not Compile_Time_Known_Value
(Lo
)
4390 or else not Compile_Time_Known_Value
(Hi
)
4395 if Is_Discrete_Type
(Typ
) then
4396 return Expr_Value
(Lo
) > Expr_Value
(Hi
);
4399 pragma Assert
(Is_Real_Type
(Typ
));
4400 return Expr_Value_R
(Lo
) > Expr_Value_R
(Hi
);
4404 -----------------------------
4405 -- Is_OK_Static_Expression --
4406 -----------------------------
4408 function Is_OK_Static_Expression
(N
: Node_Id
) return Boolean is
4410 return Is_Static_Expression
(N
)
4411 and then not Raises_Constraint_Error
(N
);
4412 end Is_OK_Static_Expression
;
4414 ------------------------
4415 -- Is_OK_Static_Range --
4416 ------------------------
4418 -- A static range is a range whose bounds are static expressions, or a
4419 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4420 -- We have already converted range attribute references, so we get the
4421 -- "or" part of this rule without needing a special test.
4423 function Is_OK_Static_Range
(N
: Node_Id
) return Boolean is
4425 return Is_OK_Static_Expression
(Low_Bound
(N
))
4426 and then Is_OK_Static_Expression
(High_Bound
(N
));
4427 end Is_OK_Static_Range
;
4429 --------------------------
4430 -- Is_OK_Static_Subtype --
4431 --------------------------
4433 -- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
4434 -- neither bound raises constraint error when evaluated.
4436 function Is_OK_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
4437 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
4438 Anc_Subt
: Entity_Id
;
4441 -- First a quick check on the non static subtype flag. As described
4442 -- in further detail in Einfo, this flag is not decisive in all cases,
4443 -- but if it is set, then the subtype is definitely non-static.
4445 if Is_Non_Static_Subtype
(Typ
) then
4449 Anc_Subt
:= Ancestor_Subtype
(Typ
);
4451 if Anc_Subt
= Empty
then
4455 if Is_Generic_Type
(Root_Type
(Base_T
))
4456 or else Is_Generic_Actual_Type
(Base_T
)
4462 elsif Is_String_Type
(Typ
) then
4464 Ekind
(Typ
) = E_String_Literal_Subtype
4466 (Is_OK_Static_Subtype
(Component_Type
(Typ
))
4467 and then Is_OK_Static_Subtype
(Etype
(First_Index
(Typ
))));
4471 elsif Is_Scalar_Type
(Typ
) then
4472 if Base_T
= Typ
then
4476 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
4477 -- Get_Type_{Low,High}_Bound.
4479 return Is_OK_Static_Subtype
(Anc_Subt
)
4480 and then Is_OK_Static_Expression
(Type_Low_Bound
(Typ
))
4481 and then Is_OK_Static_Expression
(Type_High_Bound
(Typ
));
4484 -- Types other than string and scalar types are never static
4489 end Is_OK_Static_Subtype
;
4491 ---------------------
4492 -- Is_Out_Of_Range --
4493 ---------------------
4495 function Is_Out_Of_Range
4498 Assume_Valid
: Boolean := False;
4499 Fixed_Int
: Boolean := False;
4500 Int_Real
: Boolean := False) return Boolean
4503 return Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
)
4505 end Is_Out_Of_Range
;
4507 ---------------------
4508 -- Is_Static_Range --
4509 ---------------------
4511 -- A static range is a range whose bounds are static expressions, or a
4512 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4513 -- We have already converted range attribute references, so we get the
4514 -- "or" part of this rule without needing a special test.
4516 function Is_Static_Range
(N
: Node_Id
) return Boolean is
4518 return Is_Static_Expression
(Low_Bound
(N
))
4519 and then Is_Static_Expression
(High_Bound
(N
));
4520 end Is_Static_Range
;
4522 -----------------------
4523 -- Is_Static_Subtype --
4524 -----------------------
4526 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
4528 function Is_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
4529 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
4530 Anc_Subt
: Entity_Id
;
4533 -- First a quick check on the non static subtype flag. As described
4534 -- in further detail in Einfo, this flag is not decisive in all cases,
4535 -- but if it is set, then the subtype is definitely non-static.
4537 if Is_Non_Static_Subtype
(Typ
) then
4541 Anc_Subt
:= Ancestor_Subtype
(Typ
);
4543 if Anc_Subt
= Empty
then
4547 if Is_Generic_Type
(Root_Type
(Base_T
))
4548 or else Is_Generic_Actual_Type
(Base_T
)
4554 elsif Is_String_Type
(Typ
) then
4556 Ekind
(Typ
) = E_String_Literal_Subtype
4557 or else (Is_Static_Subtype
(Component_Type
(Typ
))
4558 and then Is_Static_Subtype
(Etype
(First_Index
(Typ
))));
4562 elsif Is_Scalar_Type
(Typ
) then
4563 if Base_T
= Typ
then
4567 return Is_Static_Subtype
(Anc_Subt
)
4568 and then Is_Static_Expression
(Type_Low_Bound
(Typ
))
4569 and then Is_Static_Expression
(Type_High_Bound
(Typ
));
4572 -- Types other than string and scalar types are never static
4577 end Is_Static_Subtype
;
4579 --------------------
4580 -- Not_Null_Range --
4581 --------------------
4583 function Not_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
4584 Typ
: constant Entity_Id
:= Etype
(Lo
);
4587 if not Compile_Time_Known_Value
(Lo
)
4588 or else not Compile_Time_Known_Value
(Hi
)
4593 if Is_Discrete_Type
(Typ
) then
4594 return Expr_Value
(Lo
) <= Expr_Value
(Hi
);
4597 pragma Assert
(Is_Real_Type
(Typ
));
4599 return Expr_Value_R
(Lo
) <= Expr_Value_R
(Hi
);
4607 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean is
4609 -- We allow a maximum of 500,000 bits which seems a reasonable limit
4611 if Bits
< 500_000
then
4615 Error_Msg_N
("static value too large, capacity exceeded", N
);
4624 procedure Out_Of_Range
(N
: Node_Id
) is
4626 -- If we have the static expression case, then this is an illegality
4627 -- in Ada 95 mode, except that in an instance, we never generate an
4628 -- error (if the error is legitimate, it was already diagnosed in the
4629 -- template). The expression to compute the length of a packed array is
4630 -- attached to the array type itself, and deserves a separate message.
4632 if Is_Static_Expression
(N
)
4633 and then not In_Instance
4634 and then not In_Inlined_Body
4635 and then Ada_Version
>= Ada_95
4637 if Nkind
(Parent
(N
)) = N_Defining_Identifier
4638 and then Is_Array_Type
(Parent
(N
))
4639 and then Present
(Packed_Array_Type
(Parent
(N
)))
4640 and then Present
(First_Rep_Item
(Parent
(N
)))
4643 ("length of packed array must not exceed Integer''Last",
4644 First_Rep_Item
(Parent
(N
)));
4645 Rewrite
(N
, Make_Integer_Literal
(Sloc
(N
), Uint_1
));
4648 Apply_Compile_Time_Constraint_Error
4649 (N
, "value not in range of}", CE_Range_Check_Failed
);
4652 -- Here we generate a warning for the Ada 83 case, or when we are in an
4653 -- instance, or when we have a non-static expression case.
4656 Apply_Compile_Time_Constraint_Error
4657 (N
, "value not in range of}??", CE_Range_Check_Failed
);
4661 -------------------------
4662 -- Rewrite_In_Raise_CE --
4663 -------------------------
4665 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
) is
4666 Typ
: constant Entity_Id
:= Etype
(N
);
4669 -- If we want to raise CE in the condition of a N_Raise_CE node
4670 -- we may as well get rid of the condition.
4672 if Present
(Parent
(N
))
4673 and then Nkind
(Parent
(N
)) = N_Raise_Constraint_Error
4675 Set_Condition
(Parent
(N
), Empty
);
4677 -- If the expression raising CE is a N_Raise_CE node, we can use that
4678 -- one. We just preserve the type of the context.
4680 elsif Nkind
(Exp
) = N_Raise_Constraint_Error
then
4684 -- Else build an explcit N_Raise_CE
4688 Make_Raise_Constraint_Error
(Sloc
(Exp
),
4689 Reason
=> CE_Range_Check_Failed
));
4690 Set_Raises_Constraint_Error
(N
);
4693 end Rewrite_In_Raise_CE
;
4695 ---------------------
4696 -- String_Type_Len --
4697 ---------------------
4699 function String_Type_Len
(Stype
: Entity_Id
) return Uint
is
4700 NT
: constant Entity_Id
:= Etype
(First_Index
(Stype
));
4704 if Is_OK_Static_Subtype
(NT
) then
4707 T
:= Base_Type
(NT
);
4710 return Expr_Value
(Type_High_Bound
(T
)) -
4711 Expr_Value
(Type_Low_Bound
(T
)) + 1;
4712 end String_Type_Len
;
4714 ------------------------------------
4715 -- Subtypes_Statically_Compatible --
4716 ------------------------------------
4718 function Subtypes_Statically_Compatible
4720 T2
: Entity_Id
) return Boolean
4725 if Is_Scalar_Type
(T1
) then
4727 -- Definitely compatible if we match
4729 if Subtypes_Statically_Match
(T1
, T2
) then
4732 -- If either subtype is nonstatic then they're not compatible
4734 elsif not Is_Static_Subtype
(T1
)
4735 or else not Is_Static_Subtype
(T2
)
4739 -- If either type has constraint error bounds, then consider that
4740 -- they match to avoid junk cascaded errors here.
4742 elsif not Is_OK_Static_Subtype
(T1
)
4743 or else not Is_OK_Static_Subtype
(T2
)
4747 -- Base types must match, but we don't check that (should we???) but
4748 -- we do at least check that both types are real, or both types are
4751 elsif Is_Real_Type
(T1
) /= Is_Real_Type
(T2
) then
4754 -- Here we check the bounds
4758 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
4759 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
4760 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
4761 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
4764 if Is_Real_Type
(T1
) then
4766 (Expr_Value_R
(LB1
) > Expr_Value_R
(HB1
))
4768 (Expr_Value_R
(LB2
) <= Expr_Value_R
(LB1
)
4770 Expr_Value_R
(HB1
) <= Expr_Value_R
(HB2
));
4774 (Expr_Value
(LB1
) > Expr_Value
(HB1
))
4776 (Expr_Value
(LB2
) <= Expr_Value
(LB1
)
4778 Expr_Value
(HB1
) <= Expr_Value
(HB2
));
4785 elsif Is_Access_Type
(T1
) then
4786 return (not Is_Constrained
(T2
)
4787 or else (Subtypes_Statically_Match
4788 (Designated_Type
(T1
), Designated_Type
(T2
))))
4789 and then not (Can_Never_Be_Null
(T2
)
4790 and then not Can_Never_Be_Null
(T1
));
4795 return (Is_Composite_Type
(T1
) and then not Is_Constrained
(T2
))
4796 or else Subtypes_Statically_Match
(T1
, T2
);
4798 end Subtypes_Statically_Compatible
;
4800 -------------------------------
4801 -- Subtypes_Statically_Match --
4802 -------------------------------
4804 -- Subtypes statically match if they have statically matching constraints
4805 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
4806 -- they are the same identical constraint, or if they are static and the
4807 -- values match (RM 4.9.1(1)).
4809 function Subtypes_Statically_Match
(T1
, T2
: Entity_Id
) return Boolean is
4811 function Predicates_Match
return Boolean;
4812 -- In Ada 2012, subtypes statically match if their static predicates
4815 ----------------------
4816 -- Predicates_Match --
4817 ----------------------
4819 function Predicates_Match
return Boolean is
4824 if Ada_Version
< Ada_2012
then
4827 elsif Has_Predicates
(T1
) /= Has_Predicates
(T2
) then
4833 (T1
, Name_Static_Predicate
, Check_Parents
=> False);
4836 (T2
, Name_Static_Predicate
, Check_Parents
=> False);
4838 -- Subtypes statically match if the predicate comes from the
4839 -- same declaration, which can only happen if one is a subtype
4840 -- of the other and has no explicit predicate.
4842 -- Suppress warnings on order of actuals, which is otherwise
4843 -- triggered by one of the two calls below.
4845 pragma Warnings
(Off
);
4846 return Pred1
= Pred2
4847 or else (No
(Pred1
) and then Is_Subtype_Of
(T1
, T2
))
4848 or else (No
(Pred2
) and then Is_Subtype_Of
(T2
, T1
));
4849 pragma Warnings
(On
);
4851 end Predicates_Match
;
4853 -- Start of processing for Subtypes_Statically_Match
4856 -- A type always statically matches itself
4863 elsif Is_Scalar_Type
(T1
) then
4865 -- Base types must be the same
4867 if Base_Type
(T1
) /= Base_Type
(T2
) then
4871 -- A constrained numeric subtype never matches an unconstrained
4872 -- subtype, i.e. both types must be constrained or unconstrained.
4874 -- To understand the requirement for this test, see RM 4.9.1(1).
4875 -- As is made clear in RM 3.5.4(11), type Integer, for example is
4876 -- a constrained subtype with constraint bounds matching the bounds
4877 -- of its corresponding unconstrained base type. In this situation,
4878 -- Integer and Integer'Base do not statically match, even though
4879 -- they have the same bounds.
4881 -- We only apply this test to types in Standard and types that appear
4882 -- in user programs. That way, we do not have to be too careful about
4883 -- setting Is_Constrained right for Itypes.
4885 if Is_Numeric_Type
(T1
)
4886 and then (Is_Constrained
(T1
) /= Is_Constrained
(T2
))
4887 and then (Scope
(T1
) = Standard_Standard
4888 or else Comes_From_Source
(T1
))
4889 and then (Scope
(T2
) = Standard_Standard
4890 or else Comes_From_Source
(T2
))
4894 -- A generic scalar type does not statically match its base type
4895 -- (AI-311). In this case we make sure that the formals, which are
4896 -- first subtypes of their bases, are constrained.
4898 elsif Is_Generic_Type
(T1
)
4899 and then Is_Generic_Type
(T2
)
4900 and then (Is_Constrained
(T1
) /= Is_Constrained
(T2
))
4905 -- If there was an error in either range, then just assume the types
4906 -- statically match to avoid further junk errors.
4908 if No
(Scalar_Range
(T1
)) or else No
(Scalar_Range
(T2
))
4909 or else Error_Posted
(Scalar_Range
(T1
))
4910 or else Error_Posted
(Scalar_Range
(T2
))
4915 -- Otherwise both types have bound that can be compared
4918 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
4919 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
4920 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
4921 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
4924 -- If the bounds are the same tree node, then match if and only
4925 -- if any predicates present also match.
4927 if LB1
= LB2
and then HB1
= HB2
then
4928 return Predicates_Match
;
4930 -- Otherwise bounds must be static and identical value
4933 if not Is_Static_Subtype
(T1
)
4934 or else not Is_Static_Subtype
(T2
)
4938 -- If either type has constraint error bounds, then say that
4939 -- they match to avoid junk cascaded errors here.
4941 elsif not Is_OK_Static_Subtype
(T1
)
4942 or else not Is_OK_Static_Subtype
(T2
)
4946 elsif Is_Real_Type
(T1
) then
4948 (Expr_Value_R
(LB1
) = Expr_Value_R
(LB2
))
4950 (Expr_Value_R
(HB1
) = Expr_Value_R
(HB2
));
4954 Expr_Value
(LB1
) = Expr_Value
(LB2
)
4956 Expr_Value
(HB1
) = Expr_Value
(HB2
);
4961 -- Type with discriminants
4963 elsif Has_Discriminants
(T1
) or else Has_Discriminants
(T2
) then
4965 -- Because of view exchanges in multiple instantiations, conformance
4966 -- checking might try to match a partial view of a type with no
4967 -- discriminants with a full view that has defaulted discriminants.
4968 -- In such a case, use the discriminant constraint of the full view,
4969 -- which must exist because we know that the two subtypes have the
4972 if Has_Discriminants
(T1
) /= Has_Discriminants
(T2
) then
4974 if Is_Private_Type
(T2
)
4975 and then Present
(Full_View
(T2
))
4976 and then Has_Discriminants
(Full_View
(T2
))
4978 return Subtypes_Statically_Match
(T1
, Full_View
(T2
));
4980 elsif Is_Private_Type
(T1
)
4981 and then Present
(Full_View
(T1
))
4982 and then Has_Discriminants
(Full_View
(T1
))
4984 return Subtypes_Statically_Match
(Full_View
(T1
), T2
);
4995 DL1
: constant Elist_Id
:= Discriminant_Constraint
(T1
);
4996 DL2
: constant Elist_Id
:= Discriminant_Constraint
(T2
);
5004 elsif Is_Constrained
(T1
) /= Is_Constrained
(T2
) then
5008 -- Now loop through the discriminant constraints
5010 -- Note: the guard here seems necessary, since it is possible at
5011 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
5013 if Present
(DL1
) and then Present
(DL2
) then
5014 DA1
:= First_Elmt
(DL1
);
5015 DA2
:= First_Elmt
(DL2
);
5016 while Present
(DA1
) loop
5018 Expr1
: constant Node_Id
:= Node
(DA1
);
5019 Expr2
: constant Node_Id
:= Node
(DA2
);
5022 if not Is_Static_Expression
(Expr1
)
5023 or else not Is_Static_Expression
(Expr2
)
5027 -- If either expression raised a constraint error,
5028 -- consider the expressions as matching, since this
5029 -- helps to prevent cascading errors.
5031 elsif Raises_Constraint_Error
(Expr1
)
5032 or else Raises_Constraint_Error
(Expr2
)
5036 elsif Expr_Value
(Expr1
) /= Expr_Value
(Expr2
) then
5049 -- A definite type does not match an indefinite or classwide type.
5050 -- However, a generic type with unknown discriminants may be
5051 -- instantiated with a type with no discriminants, and conformance
5052 -- checking on an inherited operation may compare the actual with the
5053 -- subtype that renames it in the instance.
5056 Has_Unknown_Discriminants
(T1
) /= Has_Unknown_Discriminants
(T2
)
5059 Is_Generic_Actual_Type
(T1
) or else Is_Generic_Actual_Type
(T2
);
5063 elsif Is_Array_Type
(T1
) then
5065 -- If either subtype is unconstrained then both must be, and if both
5066 -- are unconstrained then no further checking is needed.
5068 if not Is_Constrained
(T1
) or else not Is_Constrained
(T2
) then
5069 return not (Is_Constrained
(T1
) or else Is_Constrained
(T2
));
5072 -- Both subtypes are constrained, so check that the index subtypes
5073 -- statically match.
5076 Index1
: Node_Id
:= First_Index
(T1
);
5077 Index2
: Node_Id
:= First_Index
(T2
);
5080 while Present
(Index1
) loop
5082 Subtypes_Statically_Match
(Etype
(Index1
), Etype
(Index2
))
5087 Next_Index
(Index1
);
5088 Next_Index
(Index2
);
5094 elsif Is_Access_Type
(T1
) then
5095 if Can_Never_Be_Null
(T1
) /= Can_Never_Be_Null
(T2
) then
5098 elsif Ekind_In
(T1
, E_Access_Subprogram_Type
,
5099 E_Anonymous_Access_Subprogram_Type
)
5103 (Designated_Type
(T1
),
5104 Designated_Type
(T2
));
5107 Subtypes_Statically_Match
5108 (Designated_Type
(T1
),
5109 Designated_Type
(T2
))
5110 and then Is_Access_Constant
(T1
) = Is_Access_Constant
(T2
);
5113 -- All other types definitely match
5118 end Subtypes_Statically_Match
;
5124 function Test
(Cond
: Boolean) return Uint
is
5133 ---------------------------------
5134 -- Test_Expression_Is_Foldable --
5135 ---------------------------------
5139 procedure Test_Expression_Is_Foldable
5149 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
5153 -- If operand is Any_Type, just propagate to result and do not
5154 -- try to fold, this prevents cascaded errors.
5156 if Etype
(Op1
) = Any_Type
then
5157 Set_Etype
(N
, Any_Type
);
5160 -- If operand raises constraint error, then replace node N with the
5161 -- raise constraint error node, and we are obviously not foldable.
5162 -- Note that this replacement inherits the Is_Static_Expression flag
5163 -- from the operand.
5165 elsif Raises_Constraint_Error
(Op1
) then
5166 Rewrite_In_Raise_CE
(N
, Op1
);
5169 -- If the operand is not static, then the result is not static, and
5170 -- all we have to do is to check the operand since it is now known
5171 -- to appear in a non-static context.
5173 elsif not Is_Static_Expression
(Op1
) then
5174 Check_Non_Static_Context
(Op1
);
5175 Fold
:= Compile_Time_Known_Value
(Op1
);
5178 -- An expression of a formal modular type is not foldable because
5179 -- the modulus is unknown.
5181 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
5182 and then Is_Generic_Type
(Etype
(Op1
))
5184 Check_Non_Static_Context
(Op1
);
5187 -- Here we have the case of an operand whose type is OK, which is
5188 -- static, and which does not raise constraint error, we can fold.
5191 Set_Is_Static_Expression
(N
);
5195 end Test_Expression_Is_Foldable
;
5199 procedure Test_Expression_Is_Foldable
5206 Rstat
: constant Boolean := Is_Static_Expression
(Op1
)
5207 and then Is_Static_Expression
(Op2
);
5213 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
5217 -- If either operand is Any_Type, just propagate to result and
5218 -- do not try to fold, this prevents cascaded errors.
5220 if Etype
(Op1
) = Any_Type
or else Etype
(Op2
) = Any_Type
then
5221 Set_Etype
(N
, Any_Type
);
5224 -- If left operand raises constraint error, then replace node N with the
5225 -- Raise_Constraint_Error node, and we are obviously not foldable.
5226 -- Is_Static_Expression is set from the two operands in the normal way,
5227 -- and we check the right operand if it is in a non-static context.
5229 elsif Raises_Constraint_Error
(Op1
) then
5231 Check_Non_Static_Context
(Op2
);
5234 Rewrite_In_Raise_CE
(N
, Op1
);
5235 Set_Is_Static_Expression
(N
, Rstat
);
5238 -- Similar processing for the case of the right operand. Note that we
5239 -- don't use this routine for the short-circuit case, so we do not have
5240 -- to worry about that special case here.
5242 elsif Raises_Constraint_Error
(Op2
) then
5244 Check_Non_Static_Context
(Op1
);
5247 Rewrite_In_Raise_CE
(N
, Op2
);
5248 Set_Is_Static_Expression
(N
, Rstat
);
5251 -- Exclude expressions of a generic modular type, as above
5253 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
5254 and then Is_Generic_Type
(Etype
(Op1
))
5256 Check_Non_Static_Context
(Op1
);
5259 -- If result is not static, then check non-static contexts on operands
5260 -- since one of them may be static and the other one may not be static.
5262 elsif not Rstat
then
5263 Check_Non_Static_Context
(Op1
);
5264 Check_Non_Static_Context
(Op2
);
5265 Fold
:= Compile_Time_Known_Value
(Op1
)
5266 and then Compile_Time_Known_Value
(Op2
);
5269 -- Else result is static and foldable. Both operands are static, and
5270 -- neither raises constraint error, so we can definitely fold.
5273 Set_Is_Static_Expression
(N
);
5278 end Test_Expression_Is_Foldable
;
5284 function Test_In_Range
5287 Assume_Valid
: Boolean;
5288 Fixed_Int
: Boolean;
5289 Int_Real
: Boolean) return Range_Membership
5294 pragma Warnings
(Off
, Assume_Valid
);
5295 -- For now Assume_Valid is unreferenced since the current implementation
5296 -- always returns Unknown if N is not a compile time known value, but we
5297 -- keep the parameter to allow for future enhancements in which we try
5298 -- to get the information in the variable case as well.
5301 -- Universal types have no range limits, so always in range
5303 if Typ
= Universal_Integer
or else Typ
= Universal_Real
then
5306 -- Never known if not scalar type. Don't know if this can actually
5307 -- happen, but our spec allows it, so we must check!
5309 elsif not Is_Scalar_Type
(Typ
) then
5312 -- Never known if this is a generic type, since the bounds of generic
5313 -- types are junk. Note that if we only checked for static expressions
5314 -- (instead of compile time known values) below, we would not need this
5315 -- check, because values of a generic type can never be static, but they
5316 -- can be known at compile time.
5318 elsif Is_Generic_Type
(Typ
) then
5321 -- Never known unless we have a compile time known value
5323 elsif not Compile_Time_Known_Value
(N
) then
5326 -- General processing with a known compile time value
5337 Lo
:= Type_Low_Bound
(Typ
);
5338 Hi
:= Type_High_Bound
(Typ
);
5340 LB_Known
:= Compile_Time_Known_Value
(Lo
);
5341 HB_Known
:= Compile_Time_Known_Value
(Hi
);
5343 -- Fixed point types should be considered as such only if flag
5344 -- Fixed_Int is set to False.
5346 if Is_Floating_Point_Type
(Typ
)
5347 or else (Is_Fixed_Point_Type
(Typ
) and then not Fixed_Int
)
5350 Valr
:= Expr_Value_R
(N
);
5352 if LB_Known
and HB_Known
then
5353 if Valr
>= Expr_Value_R
(Lo
)
5355 Valr
<= Expr_Value_R
(Hi
)
5359 return Out_Of_Range
;
5362 elsif (LB_Known
and then Valr
< Expr_Value_R
(Lo
))
5364 (HB_Known
and then Valr
> Expr_Value_R
(Hi
))
5366 return Out_Of_Range
;
5373 Val
:= Expr_Value
(N
);
5375 if LB_Known
and HB_Known
then
5376 if Val
>= Expr_Value
(Lo
)
5378 Val
<= Expr_Value
(Hi
)
5382 return Out_Of_Range
;
5385 elsif (LB_Known
and then Val
< Expr_Value
(Lo
))
5387 (HB_Known
and then Val
> Expr_Value
(Hi
))
5389 return Out_Of_Range
;
5403 procedure To_Bits
(U
: Uint
; B
: out Bits
) is
5405 for J
in 0 .. B
'Last loop
5406 B
(J
) := (U
/ (2 ** J
)) mod 2 /= 0;
5410 --------------------
5411 -- Why_Not_Static --
5412 --------------------
5414 procedure Why_Not_Static
(Expr
: Node_Id
) is
5415 N
: constant Node_Id
:= Original_Node
(Expr
);
5419 procedure Why_Not_Static_List
(L
: List_Id
);
5420 -- A version that can be called on a list of expressions. Finds all
5421 -- non-static violations in any element of the list.
5423 -------------------------
5424 -- Why_Not_Static_List --
5425 -------------------------
5427 procedure Why_Not_Static_List
(L
: List_Id
) is
5431 if Is_Non_Empty_List
(L
) then
5433 while Present
(N
) loop
5438 end Why_Not_Static_List
;
5440 -- Start of processing for Why_Not_Static
5443 -- If in ACATS mode (debug flag 2), then suppress all these messages,
5444 -- this avoids massive updates to the ACATS base line.
5446 if Debug_Flag_2
then
5450 -- Ignore call on error or empty node
5452 if No
(Expr
) or else Nkind
(Expr
) = N_Error
then
5456 -- Preprocessing for sub expressions
5458 if Nkind
(Expr
) in N_Subexpr
then
5460 -- Nothing to do if expression is static
5462 if Is_OK_Static_Expression
(Expr
) then
5466 -- Test for constraint error raised
5468 if Raises_Constraint_Error
(Expr
) then
5470 ("expression raises exception, cannot be static " &
5471 "(RM 4.9(34))!", N
);
5475 -- If no type, then something is pretty wrong, so ignore
5477 Typ
:= Etype
(Expr
);
5483 -- Type must be scalar or string type (but allow Bignum, since this
5484 -- is really a scalar type from our point of view in this diagnosis).
5486 if not Is_Scalar_Type
(Typ
)
5487 and then not Is_String_Type
(Typ
)
5488 and then not Is_RTE
(Typ
, RE_Bignum
)
5491 ("static expression must have scalar or string type " &
5497 -- If we got through those checks, test particular node kind
5500 when N_Expanded_Name | N_Identifier | N_Operator_Symbol
=>
5503 if Is_Named_Number
(E
) then
5506 elsif Ekind
(E
) = E_Constant
then
5507 if not Is_Static_Expression
(Constant_Value
(E
)) then
5509 ("& is not a static constant (RM 4.9(5))!", N
, E
);
5514 ("& is not static constant or named number " &
5515 "(RM 4.9(5))!", N
, E
);
5518 when N_Binary_Op | N_Short_Circuit | N_Membership_Test
=>
5519 if Nkind
(N
) in N_Op_Shift
then
5521 ("shift functions are never static (RM 4.9(6,18))!", N
);
5524 Why_Not_Static
(Left_Opnd
(N
));
5525 Why_Not_Static
(Right_Opnd
(N
));
5529 Why_Not_Static
(Right_Opnd
(N
));
5531 when N_Attribute_Reference
=>
5532 Why_Not_Static_List
(Expressions
(N
));
5534 E
:= Etype
(Prefix
(N
));
5536 if E
= Standard_Void_Type
then
5540 -- Special case non-scalar'Size since this is a common error
5542 if Attribute_Name
(N
) = Name_Size
then
5544 ("size attribute is only static for static scalar type " &
5545 "(RM 4.9(7,8))", N
);
5549 elsif Is_Array_Type
(E
) then
5550 if Attribute_Name
(N
) /= Name_First
5552 Attribute_Name
(N
) /= Name_Last
5554 Attribute_Name
(N
) /= Name_Length
5557 ("static array attribute must be Length, First, or Last " &
5560 -- Since we know the expression is not-static (we already
5561 -- tested for this, must mean array is not static).
5565 ("prefix is non-static array (RM 4.9(8))!", Prefix
(N
));
5570 -- Special case generic types, since again this is a common source
5573 elsif Is_Generic_Actual_Type
(E
)
5578 ("attribute of generic type is never static " &
5579 "(RM 4.9(7,8))!", N
);
5581 elsif Is_Static_Subtype
(E
) then
5584 elsif Is_Scalar_Type
(E
) then
5586 ("prefix type for attribute is not static scalar subtype " &
5591 ("static attribute must apply to array/scalar type " &
5592 "(RM 4.9(7,8))!", N
);
5595 when N_String_Literal
=>
5597 ("subtype of string literal is non-static (RM 4.9(4))!", N
);
5599 when N_Explicit_Dereference
=>
5601 ("explicit dereference is never static (RM 4.9)!", N
);
5603 when N_Function_Call
=>
5604 Why_Not_Static_List
(Parameter_Associations
(N
));
5606 -- Complain about non-static function call unless we have Bignum
5607 -- which means that the underlying expression is really some
5608 -- scalar arithmetic operation.
5610 if not Is_RTE
(Typ
, RE_Bignum
) then
5611 Error_Msg_N
("non-static function call (RM 4.9(6,18))!", N
);
5614 when N_Parameter_Association
=>
5615 Why_Not_Static
(Explicit_Actual_Parameter
(N
));
5617 when N_Indexed_Component
=>
5619 ("indexed component is never static (RM 4.9)!", N
);
5621 when N_Procedure_Call_Statement
=>
5623 ("procedure call is never static (RM 4.9)!", N
);
5625 when N_Qualified_Expression
=>
5626 Why_Not_Static
(Expression
(N
));
5628 when N_Aggregate | N_Extension_Aggregate
=>
5630 ("an aggregate is never static (RM 4.9)!", N
);
5633 Why_Not_Static
(Low_Bound
(N
));
5634 Why_Not_Static
(High_Bound
(N
));
5636 when N_Range_Constraint
=>
5637 Why_Not_Static
(Range_Expression
(N
));
5639 when N_Subtype_Indication
=>
5640 Why_Not_Static
(Constraint
(N
));
5642 when N_Selected_Component
=>
5644 ("selected component is never static (RM 4.9)!", N
);
5648 ("slice is never static (RM 4.9)!", N
);
5650 when N_Type_Conversion
=>
5651 Why_Not_Static
(Expression
(N
));
5653 if not Is_Scalar_Type
(Entity
(Subtype_Mark
(N
)))
5654 or else not Is_Static_Subtype
(Entity
(Subtype_Mark
(N
)))
5657 ("static conversion requires static scalar subtype result " &
5661 when N_Unchecked_Type_Conversion
=>
5663 ("unchecked type conversion is never static (RM 4.9)!", N
);