1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2013, 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 Nam_In
(Attribute_Name
(N
), Name_First
, Name_Last
)
533 Xtyp
:= Etype
(Prefix
(N
));
535 -- If we have no type, then just abandon the attempt to do
536 -- a fixup, this is probably the result of some other error.
542 -- Dereference an access type
544 if Is_Access_Type
(Xtyp
) then
545 Xtyp
:= Designated_Type
(Xtyp
);
548 -- If we don't have an array type at this stage, something
549 -- is peculiar, e.g. another error, and we abandon the attempt
552 if not Is_Array_Type
(Xtyp
) then
556 -- Ignore unconstrained array, since bounds are not meaningful
558 if not Is_Constrained
(Xtyp
) then
562 if Ekind
(Xtyp
) = E_String_Literal_Subtype
then
563 if Attribute_Name
(N
) = Name_First
then
564 return String_Literal_Low_Bound
(Xtyp
);
567 return Make_Integer_Literal
(Sloc
(N
),
568 Intval
=> Intval
(String_Literal_Low_Bound
(Xtyp
))
569 + String_Literal_Length
(Xtyp
));
573 -- Find correct index type
575 Indx
:= First_Index
(Xtyp
);
577 if Present
(Expressions
(N
)) then
578 Subs
:= UI_To_Int
(Expr_Value
(First
(Expressions
(N
))));
580 for J
in 2 .. Subs
loop
581 Indx
:= Next_Index
(Indx
);
585 Xtyp
:= Etype
(Indx
);
587 if Attribute_Name
(N
) = Name_First
then
588 return Type_Low_Bound
(Xtyp
);
590 return Type_High_Bound
(Xtyp
);
597 ----------------------------
598 -- Is_Known_Valid_Operand --
599 ----------------------------
601 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean is
603 return (Is_Entity_Name
(Opnd
)
605 (Is_Known_Valid
(Entity
(Opnd
))
606 or else Ekind
(Entity
(Opnd
)) = E_In_Parameter
608 (Ekind
(Entity
(Opnd
)) in Object_Kind
609 and then Present
(Current_Value
(Entity
(Opnd
))))))
610 or else Is_OK_Static_Expression
(Opnd
);
611 end Is_Known_Valid_Operand
;
617 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean is
618 Lf
: constant Node_Id
:= Compare_Fixup
(L
);
619 Rf
: constant Node_Id
:= Compare_Fixup
(R
);
621 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean;
622 -- L, R are the Expressions values from two attribute nodes for First
623 -- or Last attributes. Either may be set to No_List if no expressions
624 -- are present (indicating subscript 1). The result is True if both
625 -- expressions represent the same subscript (note one case is where
626 -- one subscript is missing and the other is explicitly set to 1).
628 -----------------------
629 -- Is_Same_Subscript --
630 -----------------------
632 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean is
638 return Expr_Value
(First
(R
)) = Uint_1
;
643 return Expr_Value
(First
(L
)) = Uint_1
;
645 return Expr_Value
(First
(L
)) = Expr_Value
(First
(R
));
648 end Is_Same_Subscript
;
650 -- Start of processing for Is_Same_Value
653 -- Values are the same if they refer to the same entity and the
654 -- entity is non-volatile. This does not however apply to Float
655 -- types, since we may have two NaN values and they should never
658 -- If the entity is a discriminant, the two expressions may be bounds
659 -- of components of objects of the same discriminated type. The
660 -- values of the discriminants are not static, and therefore the
661 -- result is unknown.
663 -- It would be better to comment individual branches of this test ???
665 if Nkind_In
(Lf
, N_Identifier
, N_Expanded_Name
)
666 and then Nkind_In
(Rf
, N_Identifier
, N_Expanded_Name
)
667 and then Entity
(Lf
) = Entity
(Rf
)
668 and then Ekind
(Entity
(Lf
)) /= E_Discriminant
669 and then Present
(Entity
(Lf
))
670 and then not Is_Floating_Point_Type
(Etype
(L
))
671 and then not Is_Volatile_Reference
(L
)
672 and then not Is_Volatile_Reference
(R
)
676 -- Or if they are compile time known and identical
678 elsif Compile_Time_Known_Value
(Lf
)
680 Compile_Time_Known_Value
(Rf
)
681 and then Expr_Value
(Lf
) = Expr_Value
(Rf
)
685 -- False if Nkind of the two nodes is different for remaining cases
687 elsif Nkind
(Lf
) /= Nkind
(Rf
) then
690 -- True if both 'First or 'Last values applying to the same entity
691 -- (first and last don't change even if value does). Note that we
692 -- need this even with the calls to Compare_Fixup, to handle the
693 -- case of unconstrained array attributes where Compare_Fixup
694 -- cannot find useful bounds.
696 elsif Nkind
(Lf
) = N_Attribute_Reference
697 and then Attribute_Name
(Lf
) = Attribute_Name
(Rf
)
698 and then Nam_In
(Attribute_Name
(Lf
), Name_First
, Name_Last
)
699 and then Nkind_In
(Prefix
(Lf
), N_Identifier
, N_Expanded_Name
)
700 and then Nkind_In
(Prefix
(Rf
), N_Identifier
, N_Expanded_Name
)
701 and then Entity
(Prefix
(Lf
)) = Entity
(Prefix
(Rf
))
702 and then Is_Same_Subscript
(Expressions
(Lf
), Expressions
(Rf
))
706 -- True if the same selected component from the same record
708 elsif Nkind
(Lf
) = N_Selected_Component
709 and then Selector_Name
(Lf
) = Selector_Name
(Rf
)
710 and then Is_Same_Value
(Prefix
(Lf
), Prefix
(Rf
))
714 -- True if the same unary operator applied to the same operand
716 elsif Nkind
(Lf
) in N_Unary_Op
717 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
721 -- True if the same binary operator applied to the same operands
723 elsif Nkind
(Lf
) in N_Binary_Op
724 and then Is_Same_Value
(Left_Opnd
(Lf
), Left_Opnd
(Rf
))
725 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
729 -- All other cases, we can't tell, so return False
736 -- Start of processing for Compile_Time_Compare
741 -- In preanalysis mode, always return Unknown unless the expression
742 -- is static. It is too early to be thinking we know the result of a
743 -- comparison, save that judgment for the full analysis. This is
744 -- particularly important in the case of pre and postconditions, which
745 -- otherwise can be prematurely collapsed into having True or False
746 -- conditions when this is inappropriate.
748 if not (Full_Analysis
749 or else (Is_Static_Expression
(L
)
751 Is_Static_Expression
(R
)))
756 -- If either operand could raise constraint error, then we cannot
757 -- know the result at compile time (since CE may be raised!)
759 if not (Cannot_Raise_Constraint_Error
(L
)
761 Cannot_Raise_Constraint_Error
(R
))
766 -- Identical operands are most certainly equal
771 -- If expressions have no types, then do not attempt to determine if
772 -- they are the same, since something funny is going on. One case in
773 -- which this happens is during generic template analysis, when bounds
774 -- are not fully analyzed.
776 elsif No
(Ltyp
) or else No
(Rtyp
) then
779 -- We do not attempt comparisons for packed arrays arrays represented as
780 -- modular types, where the semantics of comparison is quite different.
782 elsif Is_Packed_Array_Type
(Ltyp
)
783 and then Is_Modular_Integer_Type
(Ltyp
)
787 -- For access types, the only time we know the result at compile time
788 -- (apart from identical operands, which we handled already) is if we
789 -- know one operand is null and the other is not, or both operands are
792 elsif Is_Access_Type
(Ltyp
) then
793 if Known_Null
(L
) then
794 if Known_Null
(R
) then
796 elsif Known_Non_Null
(R
) then
802 elsif Known_Non_Null
(L
) and then Known_Null
(R
) then
809 -- Case where comparison involves two compile time known values
811 elsif Compile_Time_Known_Value
(L
)
812 and then Compile_Time_Known_Value
(R
)
814 -- For the floating-point case, we have to be a little careful, since
815 -- at compile time we are dealing with universal exact values, but at
816 -- runtime, these will be in non-exact target form. That's why the
817 -- returned results are LE and GE below instead of LT and GT.
819 if Is_Floating_Point_Type
(Ltyp
)
821 Is_Floating_Point_Type
(Rtyp
)
824 Lo
: constant Ureal
:= Expr_Value_R
(L
);
825 Hi
: constant Ureal
:= Expr_Value_R
(R
);
837 -- For string types, we have two string literals and we proceed to
838 -- compare them using the Ada style dictionary string comparison.
840 elsif not Is_Scalar_Type
(Ltyp
) then
842 Lstring
: constant String_Id
:= Strval
(Expr_Value_S
(L
));
843 Rstring
: constant String_Id
:= Strval
(Expr_Value_S
(R
));
844 Llen
: constant Nat
:= String_Length
(Lstring
);
845 Rlen
: constant Nat
:= String_Length
(Rstring
);
848 for J
in 1 .. Nat
'Min (Llen
, Rlen
) loop
850 LC
: constant Char_Code
:= Get_String_Char
(Lstring
, J
);
851 RC
: constant Char_Code
:= Get_String_Char
(Rstring
, J
);
863 elsif Llen
> Rlen
then
870 -- For remaining scalar cases we know exactly (note that this does
871 -- include the fixed-point case, where we know the run time integer
876 Lo
: constant Uint
:= Expr_Value
(L
);
877 Hi
: constant Uint
:= Expr_Value
(R
);
894 -- Cases where at least one operand is not known at compile time
897 -- Remaining checks apply only for discrete types
899 if not Is_Discrete_Type
(Ltyp
)
900 or else not Is_Discrete_Type
(Rtyp
)
905 -- Defend against generic types, or actually any expressions that
906 -- contain a reference to a generic type from within a generic
907 -- template. We don't want to do any range analysis of such
908 -- expressions for two reasons. First, the bounds of a generic type
909 -- itself are junk and cannot be used for any kind of analysis.
910 -- Second, we may have a case where the range at run time is indeed
911 -- known, but we don't want to do compile time analysis in the
912 -- template based on that range since in an instance the value may be
913 -- static, and able to be elaborated without reference to the bounds
914 -- of types involved. As an example, consider:
916 -- (F'Pos (F'Last) + 1) > Integer'Last
918 -- The expression on the left side of > is Universal_Integer and thus
919 -- acquires the type Integer for evaluation at run time, and at run
920 -- time it is true that this condition is always False, but within
921 -- an instance F may be a type with a static range greater than the
922 -- range of Integer, and the expression statically evaluates to True.
924 if References_Generic_Formal_Type
(L
)
926 References_Generic_Formal_Type
(R
)
931 -- Replace types by base types for the case of entities which are
932 -- not known to have valid representations. This takes care of
933 -- properly dealing with invalid representations.
935 if not Assume_Valid
and then not Assume_No_Invalid_Values
then
936 if Is_Entity_Name
(L
) and then not Is_Known_Valid
(Entity
(L
)) then
937 Ltyp
:= Underlying_Type
(Base_Type
(Ltyp
));
940 if Is_Entity_Name
(R
) and then not Is_Known_Valid
(Entity
(R
)) then
941 Rtyp
:= Underlying_Type
(Base_Type
(Rtyp
));
945 -- First attempt is to decompose the expressions to extract a
946 -- constant offset resulting from the use of any of the forms:
953 -- Then we see if the two expressions are the same value, and if so
954 -- the result is obtained by comparing the offsets.
956 -- Note: the reason we do this test first is that it returns only
957 -- decisive results (with diff set), where other tests, like the
958 -- range test, may not be as so decisive. Consider for example
959 -- J .. J + 1. This code can conclude LT with a difference of 1,
960 -- even if the range of J is not known.
969 Compare_Decompose
(L
, Lnode
, Loffs
);
970 Compare_Decompose
(R
, Rnode
, Roffs
);
972 if Is_Same_Value
(Lnode
, Rnode
) then
973 if Loffs
= Roffs
then
976 elsif Loffs
< Roffs
then
977 Diff
.all := Roffs
- Loffs
;
981 Diff
.all := Loffs
- Roffs
;
987 -- Next, try range analysis and see if operand ranges are disjoint
995 -- True if each range is a single point
998 Determine_Range
(L
, LOK
, LLo
, LHi
, Assume_Valid
);
999 Determine_Range
(R
, ROK
, RLo
, RHi
, Assume_Valid
);
1002 Single
:= (LLo
= LHi
) and then (RLo
= RHi
);
1005 if Single
and Assume_Valid
then
1006 Diff
.all := RLo
- LLo
;
1011 elsif RHi
< LLo
then
1012 if Single
and Assume_Valid
then
1013 Diff
.all := LLo
- RLo
;
1018 elsif Single
and then LLo
= RLo
then
1020 -- If the range includes a single literal and we can assume
1021 -- validity then the result is known even if an operand is
1024 if Assume_Valid
then
1030 elsif LHi
= RLo
then
1033 elsif RHi
= LLo
then
1036 elsif not Is_Known_Valid_Operand
(L
)
1037 and then not Assume_Valid
1039 if Is_Same_Value
(L
, R
) then
1046 -- If the range of either operand cannot be determined, nothing
1047 -- further can be inferred.
1054 -- Here is where we check for comparisons against maximum bounds of
1055 -- types, where we know that no value can be outside the bounds of
1056 -- the subtype. Note that this routine is allowed to assume that all
1057 -- expressions are within their subtype bounds. Callers wishing to
1058 -- deal with possibly invalid values must in any case take special
1059 -- steps (e.g. conversions to larger types) to avoid this kind of
1060 -- optimization, which is always considered to be valid. We do not
1061 -- attempt this optimization with generic types, since the type
1062 -- bounds may not be meaningful in this case.
1064 -- We are in danger of an infinite recursion here. It does not seem
1065 -- useful to go more than one level deep, so the parameter Rec is
1066 -- used to protect ourselves against this infinite recursion.
1070 -- See if we can get a decisive check against one operand and
1071 -- a bound of the other operand (four possible tests here).
1072 -- Note that we avoid testing junk bounds of a generic type.
1074 if not Is_Generic_Type
(Rtyp
) then
1075 case Compile_Time_Compare
(L
, Type_Low_Bound
(Rtyp
),
1077 Assume_Valid
, Rec
=> True)
1079 when LT
=> return LT
;
1080 when LE
=> return LE
;
1081 when EQ
=> return LE
;
1082 when others => null;
1085 case Compile_Time_Compare
(L
, Type_High_Bound
(Rtyp
),
1087 Assume_Valid
, Rec
=> True)
1089 when GT
=> return GT
;
1090 when GE
=> return GE
;
1091 when EQ
=> return GE
;
1092 when others => null;
1096 if not Is_Generic_Type
(Ltyp
) then
1097 case Compile_Time_Compare
(Type_Low_Bound
(Ltyp
), R
,
1099 Assume_Valid
, Rec
=> True)
1101 when GT
=> return GT
;
1102 when GE
=> return GE
;
1103 when EQ
=> return GE
;
1104 when others => null;
1107 case Compile_Time_Compare
(Type_High_Bound
(Ltyp
), R
,
1109 Assume_Valid
, Rec
=> True)
1111 when LT
=> return LT
;
1112 when LE
=> return LE
;
1113 when EQ
=> return LE
;
1114 when others => null;
1119 -- Next attempt is to see if we have an entity compared with a
1120 -- compile time known value, where there is a current value
1121 -- conditional for the entity which can tell us the result.
1125 -- Entity variable (left operand)
1128 -- Value (right operand)
1131 -- If False, we have reversed the operands
1134 -- Comparison operator kind from Get_Current_Value_Condition call
1137 -- Value from Get_Current_Value_Condition call
1142 Result
: Compare_Result
;
1143 -- Known result before inversion
1146 if Is_Entity_Name
(L
)
1147 and then Compile_Time_Known_Value
(R
)
1150 Val
:= Expr_Value
(R
);
1153 elsif Is_Entity_Name
(R
)
1154 and then Compile_Time_Known_Value
(L
)
1157 Val
:= Expr_Value
(L
);
1160 -- That was the last chance at finding a compile time result
1166 Get_Current_Value_Condition
(Var
, Op
, Opn
);
1168 -- That was the last chance, so if we got nothing return
1174 Opv
:= Expr_Value
(Opn
);
1176 -- We got a comparison, so we might have something interesting
1178 -- Convert LE to LT and GE to GT, just so we have fewer cases
1180 if Op
= N_Op_Le
then
1184 elsif Op
= N_Op_Ge
then
1189 -- Deal with equality case
1191 if Op
= N_Op_Eq
then
1194 elsif Opv
< Val
then
1200 -- Deal with inequality case
1202 elsif Op
= N_Op_Ne
then
1209 -- Deal with greater than case
1211 elsif Op
= N_Op_Gt
then
1214 elsif Opv
= Val
- 1 then
1220 -- Deal with less than case
1222 else pragma Assert
(Op
= N_Op_Lt
);
1225 elsif Opv
= Val
+ 1 then
1232 -- Deal with inverting result
1236 when GT
=> return LT
;
1237 when GE
=> return LE
;
1238 when LT
=> return GT
;
1239 when LE
=> return GE
;
1240 when others => return Result
;
1247 end Compile_Time_Compare
;
1249 -------------------------------
1250 -- Compile_Time_Known_Bounds --
1251 -------------------------------
1253 function Compile_Time_Known_Bounds
(T
: Entity_Id
) return Boolean is
1258 if not Is_Array_Type
(T
) then
1262 Indx
:= First_Index
(T
);
1263 while Present
(Indx
) loop
1264 Typ
:= Underlying_Type
(Etype
(Indx
));
1266 -- Never look at junk bounds of a generic type
1268 if Is_Generic_Type
(Typ
) then
1272 -- Otherwise check bounds for compile time known
1274 if not Compile_Time_Known_Value
(Type_Low_Bound
(Typ
)) then
1276 elsif not Compile_Time_Known_Value
(Type_High_Bound
(Typ
)) then
1284 end Compile_Time_Known_Bounds
;
1286 ------------------------------
1287 -- Compile_Time_Known_Value --
1288 ------------------------------
1290 function Compile_Time_Known_Value
(Op
: Node_Id
) return Boolean is
1291 K
: constant Node_Kind
:= Nkind
(Op
);
1292 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(Op
) mod CV_Cache_Size
);
1295 -- Never known at compile time if bad type or raises constraint error
1296 -- or empty (latter case occurs only as a result of a previous error).
1299 Check_Error_Detected
;
1303 or else Etype
(Op
) = Any_Type
1304 or else Raises_Constraint_Error
(Op
)
1309 -- If this is not a static expression or a null literal, and we are in
1310 -- configurable run-time mode, then we consider it not known at compile
1311 -- time. This avoids anomalies where whether something is allowed with a
1312 -- given configurable run-time library depends on how good the compiler
1313 -- is at optimizing and knowing that things are constant when they are
1316 if Configurable_Run_Time_Mode
1317 and then K
/= N_Null
1318 and then not Is_Static_Expression
(Op
)
1320 -- We make an exception for expressions that evaluate to True/False,
1321 -- to suppress spurious checks in ZFP mode. So far we have not seen
1322 -- any negative consequences of this exception.
1324 if Is_Entity_Name
(Op
)
1325 and then Ekind
(Entity
(Op
)) = E_Enumeration_Literal
1326 and then Etype
(Entity
(Op
)) = Standard_Boolean
1335 -- If we have an entity name, then see if it is the name of a constant
1336 -- and if so, test the corresponding constant value, or the name of
1337 -- an enumeration literal, which is always a constant.
1339 if Present
(Etype
(Op
)) and then Is_Entity_Name
(Op
) then
1341 E
: constant Entity_Id
:= Entity
(Op
);
1345 -- Never known at compile time if it is a packed array value.
1346 -- We might want to try to evaluate these at compile time one
1347 -- day, but we do not make that attempt now.
1349 if Is_Packed_Array_Type
(Etype
(Op
)) then
1353 if Ekind
(E
) = E_Enumeration_Literal
then
1356 elsif Ekind
(E
) = E_Constant
then
1357 V
:= Constant_Value
(E
);
1358 return Present
(V
) and then Compile_Time_Known_Value
(V
);
1362 -- We have a value, see if it is compile time known
1365 -- Integer literals are worth storing in the cache
1367 if K
= N_Integer_Literal
then
1369 CV_Ent
.V
:= Intval
(Op
);
1372 -- Other literals and NULL are known at compile time
1375 K
= N_Character_Literal
1379 K
= N_String_Literal
1385 -- Any reference to Null_Parameter is known at compile time. No
1386 -- other attribute references (that have not already been folded)
1387 -- are known at compile time.
1389 elsif K
= N_Attribute_Reference
then
1390 return Attribute_Name
(Op
) = Name_Null_Parameter
;
1394 -- If we fall through, not known at compile time
1398 -- If we get an exception while trying to do this test, then some error
1399 -- has occurred, and we simply say that the value is not known after all
1404 end Compile_Time_Known_Value
;
1406 --------------------------------------
1407 -- Compile_Time_Known_Value_Or_Aggr --
1408 --------------------------------------
1410 function Compile_Time_Known_Value_Or_Aggr
(Op
: Node_Id
) return Boolean is
1412 -- If we have an entity name, then see if it is the name of a constant
1413 -- and if so, test the corresponding constant value, or the name of
1414 -- an enumeration literal, which is always a constant.
1416 if Is_Entity_Name
(Op
) then
1418 E
: constant Entity_Id
:= Entity
(Op
);
1422 if Ekind
(E
) = E_Enumeration_Literal
then
1425 elsif Ekind
(E
) /= E_Constant
then
1429 V
:= Constant_Value
(E
);
1431 and then Compile_Time_Known_Value_Or_Aggr
(V
);
1435 -- We have a value, see if it is compile time known
1438 if Compile_Time_Known_Value
(Op
) then
1441 elsif Nkind
(Op
) = N_Aggregate
then
1443 if Present
(Expressions
(Op
)) then
1448 Expr
:= First
(Expressions
(Op
));
1449 while Present
(Expr
) loop
1450 if not Compile_Time_Known_Value_Or_Aggr
(Expr
) then
1459 if Present
(Component_Associations
(Op
)) then
1464 Cass
:= First
(Component_Associations
(Op
));
1465 while Present
(Cass
) loop
1467 Compile_Time_Known_Value_Or_Aggr
(Expression
(Cass
))
1479 -- All other types of values are not known at compile time
1486 end Compile_Time_Known_Value_Or_Aggr
;
1492 -- This is only called for actuals of functions that are not predefined
1493 -- operators (which have already been rewritten as operators at this
1494 -- stage), so the call can never be folded, and all that needs doing for
1495 -- the actual is to do the check for a non-static context.
1497 procedure Eval_Actual
(N
: Node_Id
) is
1499 Check_Non_Static_Context
(N
);
1502 --------------------
1503 -- Eval_Allocator --
1504 --------------------
1506 -- Allocators are never static, so all we have to do is to do the
1507 -- check for a non-static context if an expression is present.
1509 procedure Eval_Allocator
(N
: Node_Id
) is
1510 Expr
: constant Node_Id
:= Expression
(N
);
1513 if Nkind
(Expr
) = N_Qualified_Expression
then
1514 Check_Non_Static_Context
(Expression
(Expr
));
1518 ------------------------
1519 -- Eval_Arithmetic_Op --
1520 ------------------------
1522 -- Arithmetic operations are static functions, so the result is static
1523 -- if both operands are static (RM 4.9(7), 4.9(20)).
1525 procedure Eval_Arithmetic_Op
(N
: Node_Id
) is
1526 Left
: constant Node_Id
:= Left_Opnd
(N
);
1527 Right
: constant Node_Id
:= Right_Opnd
(N
);
1528 Ltype
: constant Entity_Id
:= Etype
(Left
);
1529 Rtype
: constant Entity_Id
:= Etype
(Right
);
1530 Otype
: Entity_Id
:= Empty
;
1535 -- If not foldable we are done
1537 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
1543 if Is_Universal_Numeric_Type
(Etype
(Left
))
1545 Is_Universal_Numeric_Type
(Etype
(Right
))
1547 Otype
:= Find_Universal_Operator_Type
(N
);
1550 -- Fold for cases where both operands are of integer type
1552 if Is_Integer_Type
(Ltype
) and then Is_Integer_Type
(Rtype
) then
1554 Left_Int
: constant Uint
:= Expr_Value
(Left
);
1555 Right_Int
: constant Uint
:= Expr_Value
(Right
);
1562 Result
:= Left_Int
+ Right_Int
;
1564 when N_Op_Subtract
=>
1565 Result
:= Left_Int
- Right_Int
;
1567 when N_Op_Multiply
=>
1570 (Num_Bits
(Left_Int
) + Num_Bits
(Right_Int
)))
1572 Result
:= Left_Int
* Right_Int
;
1579 -- The exception Constraint_Error is raised by integer
1580 -- division, rem and mod if the right operand is zero.
1582 if Right_Int
= 0 then
1583 Apply_Compile_Time_Constraint_Error
1584 (N
, "division by zero",
1590 Result
:= Left_Int
/ Right_Int
;
1595 -- The exception Constraint_Error is raised by integer
1596 -- division, rem and mod if the right operand is zero.
1598 if Right_Int
= 0 then
1599 Apply_Compile_Time_Constraint_Error
1600 (N
, "mod with zero divisor",
1605 Result
:= Left_Int
mod Right_Int
;
1610 -- The exception Constraint_Error is raised by integer
1611 -- division, rem and mod if the right operand is zero.
1613 if Right_Int
= 0 then
1614 Apply_Compile_Time_Constraint_Error
1615 (N
, "rem with zero divisor",
1621 Result
:= Left_Int
rem Right_Int
;
1625 raise Program_Error
;
1628 -- Adjust the result by the modulus if the type is a modular type
1630 if Is_Modular_Integer_Type
(Ltype
) then
1631 Result
:= Result
mod Modulus
(Ltype
);
1633 -- For a signed integer type, check non-static overflow
1635 elsif (not Stat
) and then Is_Signed_Integer_Type
(Ltype
) then
1637 BT
: constant Entity_Id
:= Base_Type
(Ltype
);
1638 Lo
: constant Uint
:= Expr_Value
(Type_Low_Bound
(BT
));
1639 Hi
: constant Uint
:= Expr_Value
(Type_High_Bound
(BT
));
1641 if Result
< Lo
or else Result
> Hi
then
1642 Apply_Compile_Time_Constraint_Error
1643 (N
, "value not in range of }??",
1644 CE_Overflow_Check_Failed
,
1651 -- If we get here we can fold the result
1653 Fold_Uint
(N
, Result
, Stat
);
1656 -- Cases where at least one operand is a real. We handle the cases of
1657 -- both reals, or mixed/real integer cases (the latter happen only for
1658 -- divide and multiply, and the result is always real).
1660 elsif Is_Real_Type
(Ltype
) or else Is_Real_Type
(Rtype
) then
1667 if Is_Real_Type
(Ltype
) then
1668 Left_Real
:= Expr_Value_R
(Left
);
1670 Left_Real
:= UR_From_Uint
(Expr_Value
(Left
));
1673 if Is_Real_Type
(Rtype
) then
1674 Right_Real
:= Expr_Value_R
(Right
);
1676 Right_Real
:= UR_From_Uint
(Expr_Value
(Right
));
1679 if Nkind
(N
) = N_Op_Add
then
1680 Result
:= Left_Real
+ Right_Real
;
1682 elsif Nkind
(N
) = N_Op_Subtract
then
1683 Result
:= Left_Real
- Right_Real
;
1685 elsif Nkind
(N
) = N_Op_Multiply
then
1686 Result
:= Left_Real
* Right_Real
;
1688 else pragma Assert
(Nkind
(N
) = N_Op_Divide
);
1689 if UR_Is_Zero
(Right_Real
) then
1690 Apply_Compile_Time_Constraint_Error
1691 (N
, "division by zero", CE_Divide_By_Zero
);
1695 Result
:= Left_Real
/ Right_Real
;
1698 Fold_Ureal
(N
, Result
, Stat
);
1702 -- If the operator was resolved to a specific type, make sure that type
1703 -- is frozen even if the expression is folded into a literal (which has
1704 -- a universal type).
1706 if Present
(Otype
) then
1707 Freeze_Before
(N
, Otype
);
1709 end Eval_Arithmetic_Op
;
1711 ----------------------------
1712 -- Eval_Character_Literal --
1713 ----------------------------
1715 -- Nothing to be done!
1717 procedure Eval_Character_Literal
(N
: Node_Id
) is
1718 pragma Warnings
(Off
, N
);
1721 end Eval_Character_Literal
;
1727 -- Static function calls are either calls to predefined operators
1728 -- with static arguments, or calls to functions that rename a literal.
1729 -- Only the latter case is handled here, predefined operators are
1730 -- constant-folded elsewhere.
1732 -- If the function is itself inherited (see 7423-001) the literal of
1733 -- the parent type must be explicitly converted to the return type
1736 procedure Eval_Call
(N
: Node_Id
) is
1737 Loc
: constant Source_Ptr
:= Sloc
(N
);
1738 Typ
: constant Entity_Id
:= Etype
(N
);
1742 if Nkind
(N
) = N_Function_Call
1743 and then No
(Parameter_Associations
(N
))
1744 and then Is_Entity_Name
(Name
(N
))
1745 and then Present
(Alias
(Entity
(Name
(N
))))
1746 and then Is_Enumeration_Type
(Base_Type
(Typ
))
1748 Lit
:= Ultimate_Alias
(Entity
(Name
(N
)));
1750 if Ekind
(Lit
) = E_Enumeration_Literal
then
1751 if Base_Type
(Etype
(Lit
)) /= Base_Type
(Typ
) then
1753 (N
, Convert_To
(Typ
, New_Occurrence_Of
(Lit
, Loc
)));
1755 Rewrite
(N
, New_Occurrence_Of
(Lit
, Loc
));
1763 --------------------------
1764 -- Eval_Case_Expression --
1765 --------------------------
1767 -- A conditional expression is static if all its conditions and dependent
1768 -- expressions are static.
1770 procedure Eval_Case_Expression
(N
: Node_Id
) is
1773 Is_Static
: Boolean;
1781 if Is_Static_Expression
(Expression
(N
)) then
1782 Val
:= Expr_Value
(Expression
(N
));
1785 Check_Non_Static_Context
(Expression
(N
));
1789 Alt
:= First
(Alternatives
(N
));
1791 Search
: while Present
(Alt
) loop
1793 or else not Is_Static_Expression
(Expression
(Alt
))
1795 Check_Non_Static_Context
(Expression
(Alt
));
1799 Choice
:= First
(Discrete_Choices
(Alt
));
1800 while Present
(Choice
) loop
1801 if Nkind
(Choice
) = N_Others_Choice
then
1802 Result
:= Expression
(Alt
);
1805 elsif Expr_Value
(Choice
) = Val
then
1806 Result
:= Expression
(Alt
);
1819 Rewrite
(N
, Relocate_Node
(Result
));
1822 Set_Is_Static_Expression
(N
, False);
1824 end Eval_Case_Expression
;
1826 ------------------------
1827 -- Eval_Concatenation --
1828 ------------------------
1830 -- Concatenation is a static function, so the result is static if both
1831 -- operands are static (RM 4.9(7), 4.9(21)).
1833 procedure Eval_Concatenation
(N
: Node_Id
) is
1834 Left
: constant Node_Id
:= Left_Opnd
(N
);
1835 Right
: constant Node_Id
:= Right_Opnd
(N
);
1836 C_Typ
: constant Entity_Id
:= Root_Type
(Component_Type
(Etype
(N
)));
1841 -- Concatenation is never static in Ada 83, so if Ada 83 check operand
1842 -- non-static context.
1844 if Ada_Version
= Ada_83
1845 and then Comes_From_Source
(N
)
1847 Check_Non_Static_Context
(Left
);
1848 Check_Non_Static_Context
(Right
);
1852 -- If not foldable we are done. In principle concatenation that yields
1853 -- any string type is static (i.e. an array type of character types).
1854 -- However, character types can include enumeration literals, and
1855 -- concatenation in that case cannot be described by a literal, so we
1856 -- only consider the operation static if the result is an array of
1857 -- (a descendant of) a predefined character type.
1859 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
1861 if not (Is_Standard_Character_Type
(C_Typ
) and then Fold
) then
1862 Set_Is_Static_Expression
(N
, False);
1866 -- Compile time string concatenation
1868 -- ??? Note that operands that are aggregates can be marked as static,
1869 -- so we should attempt at a later stage to fold concatenations with
1873 Left_Str
: constant Node_Id
:= Get_String_Val
(Left
);
1875 Right_Str
: constant Node_Id
:= Get_String_Val
(Right
);
1876 Folded_Val
: String_Id
;
1879 -- Establish new string literal, and store left operand. We make
1880 -- sure to use the special Start_String that takes an operand if
1881 -- the left operand is a string literal. Since this is optimized
1882 -- in the case where that is the most recently created string
1883 -- literal, we ensure efficient time/space behavior for the
1884 -- case of a concatenation of a series of string literals.
1886 if Nkind
(Left_Str
) = N_String_Literal
then
1887 Left_Len
:= String_Length
(Strval
(Left_Str
));
1889 -- If the left operand is the empty string, and the right operand
1890 -- is a string literal (the case of "" & "..."), the result is the
1891 -- value of the right operand. This optimization is important when
1892 -- Is_Folded_In_Parser, to avoid copying an enormous right
1895 if Left_Len
= 0 and then Nkind
(Right_Str
) = N_String_Literal
then
1896 Folded_Val
:= Strval
(Right_Str
);
1898 Start_String
(Strval
(Left_Str
));
1903 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Left_Str
)));
1907 -- Now append the characters of the right operand, unless we
1908 -- optimized the "" & "..." case above.
1910 if Nkind
(Right_Str
) = N_String_Literal
then
1911 if Left_Len
/= 0 then
1912 Store_String_Chars
(Strval
(Right_Str
));
1913 Folded_Val
:= End_String
;
1916 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Right_Str
)));
1917 Folded_Val
:= End_String
;
1920 Set_Is_Static_Expression
(N
, Stat
);
1922 -- If left operand is the empty string, the result is the
1923 -- right operand, including its bounds if anomalous.
1926 and then Is_Array_Type
(Etype
(Right
))
1927 and then Etype
(Right
) /= Any_String
1929 Set_Etype
(N
, Etype
(Right
));
1932 Fold_Str
(N
, Folded_Val
, Static
=> Stat
);
1934 end Eval_Concatenation
;
1936 ----------------------
1937 -- Eval_Entity_Name --
1938 ----------------------
1940 -- This procedure is used for identifiers and expanded names other than
1941 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
1942 -- static if they denote a static constant (RM 4.9(6)) or if the name
1943 -- denotes an enumeration literal (RM 4.9(22)).
1945 procedure Eval_Entity_Name
(N
: Node_Id
) is
1946 Def_Id
: constant Entity_Id
:= Entity
(N
);
1950 -- Enumeration literals are always considered to be constants
1951 -- and cannot raise constraint error (RM 4.9(22)).
1953 if Ekind
(Def_Id
) = E_Enumeration_Literal
then
1954 Set_Is_Static_Expression
(N
);
1957 -- A name is static if it denotes a static constant (RM 4.9(5)), and
1958 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
1959 -- it does not violate 10.2.1(8) here, since this is not a variable.
1961 elsif Ekind
(Def_Id
) = E_Constant
then
1963 -- Deferred constants must always be treated as nonstatic
1964 -- outside the scope of their full view.
1966 if Present
(Full_View
(Def_Id
))
1967 and then not In_Open_Scopes
(Scope
(Def_Id
))
1971 Val
:= Constant_Value
(Def_Id
);
1974 if Present
(Val
) then
1975 Set_Is_Static_Expression
1976 (N
, Is_Static_Expression
(Val
)
1977 and then Is_Static_Subtype
(Etype
(Def_Id
)));
1978 Set_Raises_Constraint_Error
(N
, Raises_Constraint_Error
(Val
));
1980 if not Is_Static_Expression
(N
)
1981 and then not Is_Generic_Type
(Etype
(N
))
1983 Validate_Static_Object_Name
(N
);
1990 -- Fall through if the name is not static
1992 Validate_Static_Object_Name
(N
);
1993 end Eval_Entity_Name
;
1995 ------------------------
1996 -- Eval_If_Expression --
1997 ------------------------
1999 -- We can fold to a static expression if the condition and both dependent
2000 -- expressions are static. Otherwise, the only required processing is to do
2001 -- the check for non-static context for the then and else expressions.
2003 procedure Eval_If_Expression
(N
: Node_Id
) is
2004 Condition
: constant Node_Id
:= First
(Expressions
(N
));
2005 Then_Expr
: constant Node_Id
:= Next
(Condition
);
2006 Else_Expr
: constant Node_Id
:= Next
(Then_Expr
);
2008 Non_Result
: Node_Id
;
2010 Rstat
: constant Boolean :=
2011 Is_Static_Expression
(Condition
)
2013 Is_Static_Expression
(Then_Expr
)
2015 Is_Static_Expression
(Else_Expr
);
2018 -- If any operand is Any_Type, just propagate to result and do not try
2019 -- to fold, this prevents cascaded errors.
2021 if Etype
(Condition
) = Any_Type
or else
2022 Etype
(Then_Expr
) = Any_Type
or else
2023 Etype
(Else_Expr
) = Any_Type
2025 Set_Etype
(N
, Any_Type
);
2026 Set_Is_Static_Expression
(N
, False);
2029 -- Static case where we can fold. Note that we don't try to fold cases
2030 -- where the condition is known at compile time, but the result is
2031 -- non-static. This avoids possible cases of infinite recursion where
2032 -- the expander puts in a redundant test and we remove it. Instead we
2033 -- deal with these cases in the expander.
2037 -- Select result operand
2039 if Is_True
(Expr_Value
(Condition
)) then
2040 Result
:= Then_Expr
;
2041 Non_Result
:= Else_Expr
;
2043 Result
:= Else_Expr
;
2044 Non_Result
:= Then_Expr
;
2047 -- Note that it does not matter if the non-result operand raises a
2048 -- Constraint_Error, but if the result raises constraint error then
2049 -- we replace the node with a raise constraint error. This will
2050 -- properly propagate Raises_Constraint_Error since this flag is
2053 if Raises_Constraint_Error
(Result
) then
2054 Rewrite_In_Raise_CE
(N
, Result
);
2055 Check_Non_Static_Context
(Non_Result
);
2057 -- Otherwise the result operand replaces the original node
2060 Rewrite
(N
, Relocate_Node
(Result
));
2063 -- Case of condition not known at compile time
2066 Check_Non_Static_Context
(Condition
);
2067 Check_Non_Static_Context
(Then_Expr
);
2068 Check_Non_Static_Context
(Else_Expr
);
2071 Set_Is_Static_Expression
(N
, Rstat
);
2072 end Eval_If_Expression
;
2074 ----------------------------
2075 -- Eval_Indexed_Component --
2076 ----------------------------
2078 -- Indexed components are never static, so we need to perform the check
2079 -- for non-static context on the index values. Then, we check if the
2080 -- value can be obtained at compile time, even though it is non-static.
2082 procedure Eval_Indexed_Component
(N
: Node_Id
) is
2086 -- Check for non-static context on index values
2088 Expr
:= First
(Expressions
(N
));
2089 while Present
(Expr
) loop
2090 Check_Non_Static_Context
(Expr
);
2094 -- If the indexed component appears in an object renaming declaration
2095 -- then we do not want to try to evaluate it, since in this case we
2096 -- need the identity of the array element.
2098 if Nkind
(Parent
(N
)) = N_Object_Renaming_Declaration
then
2101 -- Similarly if the indexed component appears as the prefix of an
2102 -- attribute we don't want to evaluate it, because at least for
2103 -- some cases of attributes we need the identify (e.g. Access, Size)
2105 elsif Nkind
(Parent
(N
)) = N_Attribute_Reference
then
2109 -- Note: there are other cases, such as the left side of an assignment,
2110 -- or an OUT parameter for a call, where the replacement results in the
2111 -- illegal use of a constant, But these cases are illegal in the first
2112 -- place, so the replacement, though silly, is harmless.
2114 -- Now see if this is a constant array reference
2116 if List_Length
(Expressions
(N
)) = 1
2117 and then Is_Entity_Name
(Prefix
(N
))
2118 and then Ekind
(Entity
(Prefix
(N
))) = E_Constant
2119 and then Present
(Constant_Value
(Entity
(Prefix
(N
))))
2122 Loc
: constant Source_Ptr
:= Sloc
(N
);
2123 Arr
: constant Node_Id
:= Constant_Value
(Entity
(Prefix
(N
)));
2124 Sub
: constant Node_Id
:= First
(Expressions
(N
));
2130 -- Linear one's origin subscript value for array reference
2133 -- Lower bound of the first array index
2136 -- Value from constant array
2139 Atyp
:= Etype
(Arr
);
2141 if Is_Access_Type
(Atyp
) then
2142 Atyp
:= Designated_Type
(Atyp
);
2145 -- If we have an array type (we should have but perhaps there are
2146 -- error cases where this is not the case), then see if we can do
2147 -- a constant evaluation of the array reference.
2149 if Is_Array_Type
(Atyp
) and then Atyp
/= Any_Composite
then
2150 if Ekind
(Atyp
) = E_String_Literal_Subtype
then
2151 Lbd
:= String_Literal_Low_Bound
(Atyp
);
2153 Lbd
:= Type_Low_Bound
(Etype
(First_Index
(Atyp
)));
2156 if Compile_Time_Known_Value
(Sub
)
2157 and then Nkind
(Arr
) = N_Aggregate
2158 and then Compile_Time_Known_Value
(Lbd
)
2159 and then Is_Discrete_Type
(Component_Type
(Atyp
))
2161 Lin
:= UI_To_Int
(Expr_Value
(Sub
) - Expr_Value
(Lbd
)) + 1;
2163 if List_Length
(Expressions
(Arr
)) >= Lin
then
2164 Elm
:= Pick
(Expressions
(Arr
), Lin
);
2166 -- If the resulting expression is compile time known,
2167 -- then we can rewrite the indexed component with this
2168 -- value, being sure to mark the result as non-static.
2169 -- We also reset the Sloc, in case this generates an
2170 -- error later on (e.g. 136'Access).
2172 if Compile_Time_Known_Value
(Elm
) then
2173 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2174 Set_Is_Static_Expression
(N
, False);
2179 -- We can also constant-fold if the prefix is a string literal.
2180 -- This will be useful in an instantiation or an inlining.
2182 elsif Compile_Time_Known_Value
(Sub
)
2183 and then Nkind
(Arr
) = N_String_Literal
2184 and then Compile_Time_Known_Value
(Lbd
)
2185 and then Expr_Value
(Lbd
) = 1
2186 and then Expr_Value
(Sub
) <=
2187 String_Literal_Length
(Etype
(Arr
))
2190 C
: constant Char_Code
:=
2191 Get_String_Char
(Strval
(Arr
),
2192 UI_To_Int
(Expr_Value
(Sub
)));
2194 Set_Character_Literal_Name
(C
);
2197 Make_Character_Literal
(Loc
,
2199 Char_Literal_Value
=> UI_From_CC
(C
));
2200 Set_Etype
(Elm
, Component_Type
(Atyp
));
2201 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2202 Set_Is_Static_Expression
(N
, False);
2208 end Eval_Indexed_Component
;
2210 --------------------------
2211 -- Eval_Integer_Literal --
2212 --------------------------
2214 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2215 -- as static by the analyzer. The reason we did it that early is to allow
2216 -- the possibility of turning off the Is_Static_Expression flag after
2217 -- analysis, but before resolution, when integer literals are generated in
2218 -- the expander that do not correspond to static expressions.
2220 procedure Eval_Integer_Literal
(N
: Node_Id
) is
2221 T
: constant Entity_Id
:= Etype
(N
);
2223 function In_Any_Integer_Context
return Boolean;
2224 -- If the literal is resolved with a specific type in a context where
2225 -- the expected type is Any_Integer, there are no range checks on the
2226 -- literal. By the time the literal is evaluated, it carries the type
2227 -- imposed by the enclosing expression, and we must recover the context
2228 -- to determine that Any_Integer is meant.
2230 ----------------------------
2231 -- In_Any_Integer_Context --
2232 ----------------------------
2234 function In_Any_Integer_Context
return Boolean is
2235 Par
: constant Node_Id
:= Parent
(N
);
2236 K
: constant Node_Kind
:= Nkind
(Par
);
2239 -- Any_Integer also appears in digits specifications for real types,
2240 -- but those have bounds smaller that those of any integer base type,
2241 -- so we can safely ignore these cases.
2243 return K
= N_Number_Declaration
2244 or else K
= N_Attribute_Reference
2245 or else K
= N_Attribute_Definition_Clause
2246 or else K
= N_Modular_Type_Definition
2247 or else K
= N_Signed_Integer_Type_Definition
;
2248 end In_Any_Integer_Context
;
2250 -- Start of processing for Eval_Integer_Literal
2254 -- If the literal appears in a non-expression context, then it is
2255 -- certainly appearing in a non-static context, so check it. This is
2256 -- actually a redundant check, since Check_Non_Static_Context would
2257 -- check it, but it seems worth while avoiding the call.
2259 if Nkind
(Parent
(N
)) not in N_Subexpr
2260 and then not In_Any_Integer_Context
2262 Check_Non_Static_Context
(N
);
2265 -- Modular integer literals must be in their base range
2267 if Is_Modular_Integer_Type
(T
)
2268 and then Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True)
2272 end Eval_Integer_Literal
;
2274 ---------------------
2275 -- Eval_Logical_Op --
2276 ---------------------
2278 -- Logical operations are static functions, so the result is potentially
2279 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2281 procedure Eval_Logical_Op
(N
: Node_Id
) is
2282 Left
: constant Node_Id
:= Left_Opnd
(N
);
2283 Right
: constant Node_Id
:= Right_Opnd
(N
);
2288 -- If not foldable we are done
2290 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2296 -- Compile time evaluation of logical operation
2299 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2300 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2303 -- VMS includes bitwise operations on signed types
2305 if Is_Modular_Integer_Type
(Etype
(N
))
2306 or else Is_VMS_Operator
(Entity
(N
))
2309 Left_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2310 Right_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2313 To_Bits
(Left_Int
, Left_Bits
);
2314 To_Bits
(Right_Int
, Right_Bits
);
2316 -- Note: should really be able to use array ops instead of
2317 -- these loops, but they weren't working at the time ???
2319 if Nkind
(N
) = N_Op_And
then
2320 for J
in Left_Bits
'Range loop
2321 Left_Bits
(J
) := Left_Bits
(J
) and Right_Bits
(J
);
2324 elsif Nkind
(N
) = N_Op_Or
then
2325 for J
in Left_Bits
'Range loop
2326 Left_Bits
(J
) := Left_Bits
(J
) or Right_Bits
(J
);
2330 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2332 for J
in Left_Bits
'Range loop
2333 Left_Bits
(J
) := Left_Bits
(J
) xor Right_Bits
(J
);
2337 Fold_Uint
(N
, From_Bits
(Left_Bits
, Etype
(N
)), Stat
);
2341 pragma Assert
(Is_Boolean_Type
(Etype
(N
)));
2343 if Nkind
(N
) = N_Op_And
then
2345 Test
(Is_True
(Left_Int
) and then Is_True
(Right_Int
)), Stat
);
2347 elsif Nkind
(N
) = N_Op_Or
then
2349 Test
(Is_True
(Left_Int
) or else Is_True
(Right_Int
)), Stat
);
2352 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2354 Test
(Is_True
(Left_Int
) xor Is_True
(Right_Int
)), Stat
);
2358 end Eval_Logical_Op
;
2360 ------------------------
2361 -- Eval_Membership_Op --
2362 ------------------------
2364 -- A membership test is potentially static if the expression is static, and
2365 -- the range is a potentially static range, or is a subtype mark denoting a
2366 -- static subtype (RM 4.9(12)).
2368 procedure Eval_Membership_Op
(N
: Node_Id
) is
2369 Left
: constant Node_Id
:= Left_Opnd
(N
);
2370 Right
: constant Node_Id
:= Right_Opnd
(N
);
2379 -- Ignore if error in either operand, except to make sure that Any_Type
2380 -- is properly propagated to avoid junk cascaded errors.
2382 if Etype
(Left
) = Any_Type
or else Etype
(Right
) = Any_Type
then
2383 Set_Etype
(N
, Any_Type
);
2387 -- Ignore if types involved have predicates
2389 if Present
(Predicate_Function
(Etype
(Left
)))
2391 Present
(Predicate_Function
(Etype
(Right
)))
2396 -- Case of right operand is a subtype name
2398 if Is_Entity_Name
(Right
) then
2399 Def_Id
:= Entity
(Right
);
2401 if (Is_Scalar_Type
(Def_Id
) or else Is_String_Type
(Def_Id
))
2402 and then Is_OK_Static_Subtype
(Def_Id
)
2404 Test_Expression_Is_Foldable
(N
, Left
, Stat
, Fold
);
2406 if not Fold
or else not Stat
then
2410 Check_Non_Static_Context
(Left
);
2414 -- For string membership tests we will check the length further on
2416 if not Is_String_Type
(Def_Id
) then
2417 Lo
:= Type_Low_Bound
(Def_Id
);
2418 Hi
:= Type_High_Bound
(Def_Id
);
2425 -- Case of right operand is a range
2428 if Is_Static_Range
(Right
) then
2429 Test_Expression_Is_Foldable
(N
, Left
, Stat
, Fold
);
2431 if not Fold
or else not Stat
then
2434 -- If one bound of range raises CE, then don't try to fold
2436 elsif not Is_OK_Static_Range
(Right
) then
2437 Check_Non_Static_Context
(Left
);
2442 Check_Non_Static_Context
(Left
);
2446 -- Here we know range is an OK static range
2448 Lo
:= Low_Bound
(Right
);
2449 Hi
:= High_Bound
(Right
);
2452 -- For strings we check that the length of the string expression is
2453 -- compatible with the string subtype if the subtype is constrained,
2454 -- or if unconstrained then the test is always true.
2456 if Is_String_Type
(Etype
(Right
)) then
2457 if not Is_Constrained
(Etype
(Right
)) then
2462 Typlen
: constant Uint
:= String_Type_Len
(Etype
(Right
));
2463 Strlen
: constant Uint
:=
2465 (String_Length
(Strval
(Get_String_Val
(Left
))));
2467 Result
:= (Typlen
= Strlen
);
2471 -- Fold the membership test. We know we have a static range and Lo and
2472 -- Hi are set to the expressions for the end points of this range.
2474 elsif Is_Real_Type
(Etype
(Right
)) then
2476 Leftval
: constant Ureal
:= Expr_Value_R
(Left
);
2479 Result
:= Expr_Value_R
(Lo
) <= Leftval
2480 and then Leftval
<= Expr_Value_R
(Hi
);
2485 Leftval
: constant Uint
:= Expr_Value
(Left
);
2488 Result
:= Expr_Value
(Lo
) <= Leftval
2489 and then Leftval
<= Expr_Value
(Hi
);
2493 if Nkind
(N
) = N_Not_In
then
2494 Result
:= not Result
;
2497 Fold_Uint
(N
, Test
(Result
), True);
2499 Warn_On_Known_Condition
(N
);
2500 end Eval_Membership_Op
;
2502 ------------------------
2503 -- Eval_Named_Integer --
2504 ------------------------
2506 procedure Eval_Named_Integer
(N
: Node_Id
) is
2509 Expr_Value
(Expression
(Declaration_Node
(Entity
(N
)))), True);
2510 end Eval_Named_Integer
;
2512 ---------------------
2513 -- Eval_Named_Real --
2514 ---------------------
2516 procedure Eval_Named_Real
(N
: Node_Id
) is
2519 Expr_Value_R
(Expression
(Declaration_Node
(Entity
(N
)))), True);
2520 end Eval_Named_Real
;
2526 -- Exponentiation is a static functions, so the result is potentially
2527 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2529 procedure Eval_Op_Expon
(N
: Node_Id
) is
2530 Left
: constant Node_Id
:= Left_Opnd
(N
);
2531 Right
: constant Node_Id
:= Right_Opnd
(N
);
2536 -- If not foldable we are done
2538 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2544 -- Fold exponentiation operation
2547 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2552 if Is_Integer_Type
(Etype
(Left
)) then
2554 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2558 -- Exponentiation of an integer raises Constraint_Error for a
2559 -- negative exponent (RM 4.5.6).
2561 if Right_Int
< 0 then
2562 Apply_Compile_Time_Constraint_Error
2563 (N
, "integer exponent negative",
2564 CE_Range_Check_Failed
,
2569 if OK_Bits
(N
, Num_Bits
(Left_Int
) * Right_Int
) then
2570 Result
:= Left_Int
** Right_Int
;
2575 if Is_Modular_Integer_Type
(Etype
(N
)) then
2576 Result
:= Result
mod Modulus
(Etype
(N
));
2579 Fold_Uint
(N
, Result
, Stat
);
2587 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
2590 -- Cannot have a zero base with a negative exponent
2592 if UR_Is_Zero
(Left_Real
) then
2594 if Right_Int
< 0 then
2595 Apply_Compile_Time_Constraint_Error
2596 (N
, "zero ** negative integer",
2597 CE_Range_Check_Failed
,
2601 Fold_Ureal
(N
, Ureal_0
, Stat
);
2605 Fold_Ureal
(N
, Left_Real
** Right_Int
, Stat
);
2616 -- The not operation is a static functions, so the result is potentially
2617 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
2619 procedure Eval_Op_Not
(N
: Node_Id
) is
2620 Right
: constant Node_Id
:= Right_Opnd
(N
);
2625 -- If not foldable we are done
2627 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
2633 -- Fold not operation
2636 Rint
: constant Uint
:= Expr_Value
(Right
);
2637 Typ
: constant Entity_Id
:= Etype
(N
);
2640 -- Negation is equivalent to subtracting from the modulus minus one.
2641 -- For a binary modulus this is equivalent to the ones-complement of
2642 -- the original value. For non-binary modulus this is an arbitrary
2643 -- but consistent definition.
2645 if Is_Modular_Integer_Type
(Typ
) then
2646 Fold_Uint
(N
, Modulus
(Typ
) - 1 - Rint
, Stat
);
2649 pragma Assert
(Is_Boolean_Type
(Typ
));
2650 Fold_Uint
(N
, Test
(not Is_True
(Rint
)), Stat
);
2653 Set_Is_Static_Expression
(N
, Stat
);
2657 -------------------------------
2658 -- Eval_Qualified_Expression --
2659 -------------------------------
2661 -- A qualified expression is potentially static if its subtype mark denotes
2662 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2664 procedure Eval_Qualified_Expression
(N
: Node_Id
) is
2665 Operand
: constant Node_Id
:= Expression
(N
);
2666 Target_Type
: constant Entity_Id
:= Entity
(Subtype_Mark
(N
));
2673 -- Can only fold if target is string or scalar and subtype is static.
2674 -- Also, do not fold if our parent is an allocator (this is because the
2675 -- qualified expression is really part of the syntactic structure of an
2676 -- allocator, and we do not want to end up with something that
2677 -- corresponds to "new 1" where the 1 is the result of folding a
2678 -- qualified expression).
2680 if not Is_Static_Subtype
(Target_Type
)
2681 or else Nkind
(Parent
(N
)) = N_Allocator
2683 Check_Non_Static_Context
(Operand
);
2685 -- If operand is known to raise constraint_error, set the flag on the
2686 -- expression so it does not get optimized away.
2688 if Nkind
(Operand
) = N_Raise_Constraint_Error
then
2689 Set_Raises_Constraint_Error
(N
);
2695 -- If not foldable we are done
2697 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
2702 -- Don't try fold if target type has constraint error bounds
2704 elsif not Is_OK_Static_Subtype
(Target_Type
) then
2705 Set_Raises_Constraint_Error
(N
);
2709 -- Here we will fold, save Print_In_Hex indication
2711 Hex
:= Nkind
(Operand
) = N_Integer_Literal
2712 and then Print_In_Hex
(Operand
);
2714 -- Fold the result of qualification
2716 if Is_Discrete_Type
(Target_Type
) then
2717 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
2719 -- Preserve Print_In_Hex indication
2721 if Hex
and then Nkind
(N
) = N_Integer_Literal
then
2722 Set_Print_In_Hex
(N
);
2725 elsif Is_Real_Type
(Target_Type
) then
2726 Fold_Ureal
(N
, Expr_Value_R
(Operand
), Stat
);
2729 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Stat
);
2732 Set_Is_Static_Expression
(N
, False);
2734 Check_String_Literal_Length
(N
, Target_Type
);
2740 -- The expression may be foldable but not static
2742 Set_Is_Static_Expression
(N
, Stat
);
2744 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
2747 end Eval_Qualified_Expression
;
2749 -----------------------
2750 -- Eval_Real_Literal --
2751 -----------------------
2753 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2754 -- as static by the analyzer. The reason we did it that early is to allow
2755 -- the possibility of turning off the Is_Static_Expression flag after
2756 -- analysis, but before resolution, when integer literals are generated
2757 -- in the expander that do not correspond to static expressions.
2759 procedure Eval_Real_Literal
(N
: Node_Id
) is
2760 PK
: constant Node_Kind
:= Nkind
(Parent
(N
));
2763 -- If the literal appears in a non-expression context and not as part of
2764 -- a number declaration, then it is appearing in a non-static context,
2767 if PK
not in N_Subexpr
and then PK
/= N_Number_Declaration
then
2768 Check_Non_Static_Context
(N
);
2770 end Eval_Real_Literal
;
2772 ------------------------
2773 -- Eval_Relational_Op --
2774 ------------------------
2776 -- Relational operations are static functions, so the result is static if
2777 -- both operands are static (RM 4.9(7), 4.9(20)), except that for strings,
2778 -- the result is never static, even if the operands are.
2780 procedure Eval_Relational_Op
(N
: Node_Id
) is
2781 Left
: constant Node_Id
:= Left_Opnd
(N
);
2782 Right
: constant Node_Id
:= Right_Opnd
(N
);
2783 Typ
: constant Entity_Id
:= Etype
(Left
);
2784 Otype
: Entity_Id
:= Empty
;
2788 -- One special case to deal with first. If we can tell that the result
2789 -- will be false because the lengths of one or more index subtypes are
2790 -- compile time known and different, then we can replace the entire
2791 -- result by False. We only do this for one dimensional arrays, because
2792 -- the case of multi-dimensional arrays is rare and too much trouble! If
2793 -- one of the operands is an illegal aggregate, its type might still be
2794 -- an arbitrary composite type, so nothing to do.
2796 if Is_Array_Type
(Typ
)
2797 and then Typ
/= Any_Composite
2798 and then Number_Dimensions
(Typ
) = 1
2799 and then (Nkind
(N
) = N_Op_Eq
or else Nkind
(N
) = N_Op_Ne
)
2801 if Raises_Constraint_Error
(Left
)
2802 or else Raises_Constraint_Error
(Right
)
2807 -- OK, we have the case where we may be able to do this fold
2809 Length_Mismatch
: declare
2810 procedure Get_Static_Length
(Op
: Node_Id
; Len
: out Uint
);
2811 -- If Op is an expression for a constrained array with a known at
2812 -- compile time length, then Len is set to this (non-negative
2813 -- length). Otherwise Len is set to minus 1.
2815 -----------------------
2816 -- Get_Static_Length --
2817 -----------------------
2819 procedure Get_Static_Length
(Op
: Node_Id
; Len
: out Uint
) is
2823 -- First easy case string literal
2825 if Nkind
(Op
) = N_String_Literal
then
2826 Len
:= UI_From_Int
(String_Length
(Strval
(Op
)));
2830 -- Second easy case, not constrained subtype, so no length
2832 if not Is_Constrained
(Etype
(Op
)) then
2833 Len
:= Uint_Minus_1
;
2839 T
:= Etype
(First_Index
(Etype
(Op
)));
2841 -- The simple case, both bounds are known at compile time
2843 if Is_Discrete_Type
(T
)
2845 Compile_Time_Known_Value
(Type_Low_Bound
(T
))
2847 Compile_Time_Known_Value
(Type_High_Bound
(T
))
2849 Len
:= UI_Max
(Uint_0
,
2850 Expr_Value
(Type_High_Bound
(T
)) -
2851 Expr_Value
(Type_Low_Bound
(T
)) + 1);
2855 -- A more complex case, where the bounds are of the form
2856 -- X [+/- K1] .. X [+/- K2]), where X is an expression that is
2857 -- either A'First or A'Last (with A an entity name), or X is an
2858 -- entity name, and the two X's are the same and K1 and K2 are
2859 -- known at compile time, in this case, the length can also be
2860 -- computed at compile time, even though the bounds are not
2861 -- known. A common case of this is e.g. (X'First .. X'First+5).
2863 Extract_Length
: declare
2864 procedure Decompose_Expr
2866 Ent
: out Entity_Id
;
2867 Kind
: out Character;
2869 -- Given an expression, see if is of the form above,
2870 -- X [+/- K]. If so Ent is set to the entity in X,
2871 -- Kind is 'F','L','E' for 'First/'Last/simple entity,
2872 -- and Cons is the value of K. If the expression is
2873 -- not of the required form, Ent is set to Empty.
2875 --------------------
2876 -- Decompose_Expr --
2877 --------------------
2879 procedure Decompose_Expr
2881 Ent
: out Entity_Id
;
2882 Kind
: out Character;
2888 if Nkind
(Expr
) = N_Op_Add
2889 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
2891 Exp
:= Left_Opnd
(Expr
);
2892 Cons
:= Expr_Value
(Right_Opnd
(Expr
));
2894 elsif Nkind
(Expr
) = N_Op_Subtract
2895 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
2897 Exp
:= Left_Opnd
(Expr
);
2898 Cons
:= -Expr_Value
(Right_Opnd
(Expr
));
2900 -- If the bound is a constant created to remove side
2901 -- effects, recover original expression to see if it has
2902 -- one of the recognizable forms.
2904 elsif Nkind
(Expr
) = N_Identifier
2905 and then not Comes_From_Source
(Entity
(Expr
))
2906 and then Ekind
(Entity
(Expr
)) = E_Constant
2908 Nkind
(Parent
(Entity
(Expr
))) = N_Object_Declaration
2910 Exp
:= Expression
(Parent
(Entity
(Expr
)));
2911 Decompose_Expr
(Exp
, Ent
, Kind
, Cons
);
2913 -- If original expression includes an entity, create a
2914 -- reference to it for use below.
2916 if Present
(Ent
) then
2917 Exp
:= New_Occurrence_Of
(Ent
, Sloc
(Ent
));
2925 -- At this stage Exp is set to the potential X
2927 if Nkind
(Exp
) = N_Attribute_Reference
then
2928 if Attribute_Name
(Exp
) = Name_First
then
2931 elsif Attribute_Name
(Exp
) = Name_Last
then
2939 Exp
:= Prefix
(Exp
);
2945 if Is_Entity_Name
(Exp
)
2946 and then Present
(Entity
(Exp
))
2948 Ent
:= Entity
(Exp
);
2956 Ent1
, Ent2
: Entity_Id
;
2957 Kind1
, Kind2
: Character;
2958 Cons1
, Cons2
: Uint
;
2960 -- Start of processing for Extract_Length
2964 (Original_Node
(Type_Low_Bound
(T
)), Ent1
, Kind1
, Cons1
);
2966 (Original_Node
(Type_High_Bound
(T
)), Ent2
, Kind2
, Cons2
);
2969 and then Kind1
= Kind2
2970 and then Ent1
= Ent2
2972 Len
:= Cons2
- Cons1
+ 1;
2974 Len
:= Uint_Minus_1
;
2977 end Get_Static_Length
;
2984 -- Start of processing for Length_Mismatch
2987 Get_Static_Length
(Left
, Len_L
);
2988 Get_Static_Length
(Right
, Len_R
);
2990 if Len_L
/= Uint_Minus_1
2991 and then Len_R
/= Uint_Minus_1
2992 and then Len_L
/= Len_R
2994 Fold_Uint
(N
, Test
(Nkind
(N
) = N_Op_Ne
), False);
2995 Warn_On_Known_Condition
(N
);
2998 end Length_Mismatch
;
3002 Is_Static_Expression
: Boolean;
3003 Is_Foldable
: Boolean;
3004 pragma Unreferenced
(Is_Foldable
);
3007 -- Initialize the value of Is_Static_Expression. The value of
3008 -- Is_Foldable returned by Test_Expression_Is_Foldable is not needed
3009 -- since, even when some operand is a variable, we can still perform
3010 -- the static evaluation of the expression in some cases (for
3011 -- example, for a variable of a subtype of Integer we statically
3012 -- know that any value stored in such variable is smaller than
3015 Test_Expression_Is_Foldable
3016 (N
, Left
, Right
, Is_Static_Expression
, Is_Foldable
);
3018 -- Only comparisons of scalars can give static results. In
3019 -- particular, comparisons of strings never yield a static
3020 -- result, even if both operands are static strings.
3022 if not Is_Scalar_Type
(Typ
) then
3023 Is_Static_Expression
:= False;
3024 Set_Is_Static_Expression
(N
, False);
3027 -- For operators on universal numeric types called as functions with
3028 -- an explicit scope, determine appropriate specific numeric type,
3029 -- and diagnose possible ambiguity.
3031 if Is_Universal_Numeric_Type
(Etype
(Left
))
3033 Is_Universal_Numeric_Type
(Etype
(Right
))
3035 Otype
:= Find_Universal_Operator_Type
(N
);
3038 -- For static real type expressions, we cannot use
3039 -- Compile_Time_Compare since it worries about run-time
3040 -- results which are not exact.
3042 if Is_Static_Expression
and then Is_Real_Type
(Typ
) then
3044 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
3045 Right_Real
: constant Ureal
:= Expr_Value_R
(Right
);
3049 when N_Op_Eq
=> Result
:= (Left_Real
= Right_Real
);
3050 when N_Op_Ne
=> Result
:= (Left_Real
/= Right_Real
);
3051 when N_Op_Lt
=> Result
:= (Left_Real
< Right_Real
);
3052 when N_Op_Le
=> Result
:= (Left_Real
<= Right_Real
);
3053 when N_Op_Gt
=> Result
:= (Left_Real
> Right_Real
);
3054 when N_Op_Ge
=> Result
:= (Left_Real
>= Right_Real
);
3057 raise Program_Error
;
3060 Fold_Uint
(N
, Test
(Result
), True);
3063 -- For all other cases, we use Compile_Time_Compare to do the compare
3067 CR
: constant Compare_Result
:=
3068 Compile_Time_Compare
3069 (Left
, Right
, Assume_Valid
=> False);
3072 if CR
= Unknown
then
3080 elsif CR
= NE
or else CR
= GT
or else CR
= LT
then
3087 if CR
= NE
or else CR
= GT
or else CR
= LT
then
3098 elsif CR
= EQ
or else CR
= GT
or else CR
= GE
then
3105 if CR
= LT
or else CR
= EQ
or else CR
= LE
then
3116 elsif CR
= EQ
or else CR
= LT
or else CR
= LE
then
3123 if CR
= GT
or else CR
= EQ
or else CR
= GE
then
3132 raise Program_Error
;
3136 Fold_Uint
(N
, Test
(Result
), Is_Static_Expression
);
3140 -- For the case of a folded relational operator on a specific numeric
3141 -- type, freeze operand type now.
3143 if Present
(Otype
) then
3144 Freeze_Before
(N
, Otype
);
3147 Warn_On_Known_Condition
(N
);
3148 end Eval_Relational_Op
;
3154 -- Shift operations are intrinsic operations that can never be static, so
3155 -- the only processing required is to perform the required check for a non
3156 -- static context for the two operands.
3158 -- Actually we could do some compile time evaluation here some time ???
3160 procedure Eval_Shift
(N
: Node_Id
) is
3162 Check_Non_Static_Context
(Left_Opnd
(N
));
3163 Check_Non_Static_Context
(Right_Opnd
(N
));
3166 ------------------------
3167 -- Eval_Short_Circuit --
3168 ------------------------
3170 -- A short circuit operation is potentially static if both operands are
3171 -- potentially static (RM 4.9 (13)).
3173 procedure Eval_Short_Circuit
(N
: Node_Id
) is
3174 Kind
: constant Node_Kind
:= Nkind
(N
);
3175 Left
: constant Node_Id
:= Left_Opnd
(N
);
3176 Right
: constant Node_Id
:= Right_Opnd
(N
);
3179 Rstat
: constant Boolean :=
3180 Is_Static_Expression
(Left
)
3182 Is_Static_Expression
(Right
);
3185 -- Short circuit operations are never static in Ada 83
3187 if Ada_Version
= Ada_83
and then Comes_From_Source
(N
) then
3188 Check_Non_Static_Context
(Left
);
3189 Check_Non_Static_Context
(Right
);
3193 -- Now look at the operands, we can't quite use the normal call to
3194 -- Test_Expression_Is_Foldable here because short circuit operations
3195 -- are a special case, they can still be foldable, even if the right
3196 -- operand raises constraint error.
3198 -- If either operand is Any_Type, just propagate to result and do not
3199 -- try to fold, this prevents cascaded errors.
3201 if Etype
(Left
) = Any_Type
or else Etype
(Right
) = Any_Type
then
3202 Set_Etype
(N
, Any_Type
);
3205 -- If left operand raises constraint error, then replace node N with
3206 -- the raise constraint error node, and we are obviously not foldable.
3207 -- Is_Static_Expression is set from the two operands in the normal way,
3208 -- and we check the right operand if it is in a non-static context.
3210 elsif Raises_Constraint_Error
(Left
) then
3212 Check_Non_Static_Context
(Right
);
3215 Rewrite_In_Raise_CE
(N
, Left
);
3216 Set_Is_Static_Expression
(N
, Rstat
);
3219 -- If the result is not static, then we won't in any case fold
3221 elsif not Rstat
then
3222 Check_Non_Static_Context
(Left
);
3223 Check_Non_Static_Context
(Right
);
3227 -- Here the result is static, note that, unlike the normal processing
3228 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
3229 -- the right operand raises constraint error, that's because it is not
3230 -- significant if the left operand is decisive.
3232 Set_Is_Static_Expression
(N
);
3234 -- It does not matter if the right operand raises constraint error if
3235 -- it will not be evaluated. So deal specially with the cases where
3236 -- the right operand is not evaluated. Note that we will fold these
3237 -- cases even if the right operand is non-static, which is fine, but
3238 -- of course in these cases the result is not potentially static.
3240 Left_Int
:= Expr_Value
(Left
);
3242 if (Kind
= N_And_Then
and then Is_False
(Left_Int
))
3244 (Kind
= N_Or_Else
and then Is_True
(Left_Int
))
3246 Fold_Uint
(N
, Left_Int
, Rstat
);
3250 -- If first operand not decisive, then it does matter if the right
3251 -- operand raises constraint error, since it will be evaluated, so
3252 -- we simply replace the node with the right operand. Note that this
3253 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
3254 -- (both are set to True in Right).
3256 if Raises_Constraint_Error
(Right
) then
3257 Rewrite_In_Raise_CE
(N
, Right
);
3258 Check_Non_Static_Context
(Left
);
3262 -- Otherwise the result depends on the right operand
3264 Fold_Uint
(N
, Expr_Value
(Right
), Rstat
);
3266 end Eval_Short_Circuit
;
3272 -- Slices can never be static, so the only processing required is to check
3273 -- for non-static context if an explicit range is given.
3275 procedure Eval_Slice
(N
: Node_Id
) is
3276 Drange
: constant Node_Id
:= Discrete_Range
(N
);
3278 if Nkind
(Drange
) = N_Range
then
3279 Check_Non_Static_Context
(Low_Bound
(Drange
));
3280 Check_Non_Static_Context
(High_Bound
(Drange
));
3283 -- A slice of the form A (subtype), when the subtype is the index of
3284 -- the type of A, is redundant, the slice can be replaced with A, and
3285 -- this is worth a warning.
3287 if Is_Entity_Name
(Prefix
(N
)) then
3289 E
: constant Entity_Id
:= Entity
(Prefix
(N
));
3290 T
: constant Entity_Id
:= Etype
(E
);
3292 if Ekind
(E
) = E_Constant
3293 and then Is_Array_Type
(T
)
3294 and then Is_Entity_Name
(Drange
)
3296 if Is_Entity_Name
(Original_Node
(First_Index
(T
)))
3297 and then Entity
(Original_Node
(First_Index
(T
)))
3300 if Warn_On_Redundant_Constructs
then
3301 Error_Msg_N
("redundant slice denotes whole array?r?", N
);
3304 -- The following might be a useful optimization???
3306 -- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
3313 ---------------------------------
3314 -- Eval_Static_Predicate_Check --
3315 ---------------------------------
3317 function Eval_Static_Predicate_Check
3319 Typ
: Entity_Id
) return Boolean
3321 Loc
: constant Source_Ptr
:= Sloc
(N
);
3322 Pred
: constant List_Id
:= Static_Predicate
(Typ
);
3330 -- The static predicate is a list of alternatives in the proper format
3331 -- for an Ada 2012 membership test. If the argument is a literal, the
3332 -- membership test can be evaluated statically. The caller transforms
3333 -- a result of False into a static contraint error.
3335 Test
:= Make_In
(Loc
,
3336 Left_Opnd
=> New_Copy_Tree
(N
),
3337 Right_Opnd
=> Empty
,
3338 Alternatives
=> Pred
);
3339 Analyze_And_Resolve
(Test
, Standard_Boolean
);
3341 return Nkind
(Test
) = N_Identifier
3342 and then Entity
(Test
) = Standard_True
;
3343 end Eval_Static_Predicate_Check
;
3345 -------------------------
3346 -- Eval_String_Literal --
3347 -------------------------
3349 procedure Eval_String_Literal
(N
: Node_Id
) is
3350 Typ
: constant Entity_Id
:= Etype
(N
);
3351 Bas
: constant Entity_Id
:= Base_Type
(Typ
);
3357 -- Nothing to do if error type (handles cases like default expressions
3358 -- or generics where we have not yet fully resolved the type).
3360 if Bas
= Any_Type
or else Bas
= Any_String
then
3364 -- String literals are static if the subtype is static (RM 4.9(2)), so
3365 -- reset the static expression flag (it was set unconditionally in
3366 -- Analyze_String_Literal) if the subtype is non-static. We tell if
3367 -- the subtype is static by looking at the lower bound.
3369 if Ekind
(Typ
) = E_String_Literal_Subtype
then
3370 if not Is_OK_Static_Expression
(String_Literal_Low_Bound
(Typ
)) then
3371 Set_Is_Static_Expression
(N
, False);
3375 -- Here if Etype of string literal is normal Etype (not yet possible,
3376 -- but may be possible in future).
3378 elsif not Is_OK_Static_Expression
3379 (Type_Low_Bound
(Etype
(First_Index
(Typ
))))
3381 Set_Is_Static_Expression
(N
, False);
3385 -- If original node was a type conversion, then result if non-static
3387 if Nkind
(Original_Node
(N
)) = N_Type_Conversion
then
3388 Set_Is_Static_Expression
(N
, False);
3392 -- Test for illegal Ada 95 cases. A string literal is illegal in Ada 95
3393 -- if its bounds are outside the index base type and this index type is
3394 -- static. This can happen in only two ways. Either the string literal
3395 -- is too long, or it is null, and the lower bound is type'First. In
3396 -- either case it is the upper bound that is out of range of the index
3398 if Ada_Version
>= Ada_95
then
3399 if Root_Type
(Bas
) = Standard_String
3401 Root_Type
(Bas
) = Standard_Wide_String
3403 Root_Type
(Bas
) = Standard_Wide_Wide_String
3405 Xtp
:= Standard_Positive
;
3407 Xtp
:= Etype
(First_Index
(Bas
));
3410 if Ekind
(Typ
) = E_String_Literal_Subtype
then
3411 Lo
:= String_Literal_Low_Bound
(Typ
);
3413 Lo
:= Type_Low_Bound
(Etype
(First_Index
(Typ
)));
3416 -- Check for string too long
3418 Len
:= String_Length
(Strval
(N
));
3420 if UI_From_Int
(Len
) > String_Type_Len
(Bas
) then
3422 -- Issue message. Note that this message is a warning if the
3423 -- string literal is not marked as static (happens in some cases
3424 -- of folding strings known at compile time, but not static).
3425 -- Furthermore in such cases, we reword the message, since there
3426 -- is no string literal in the source program!
3428 if Is_Static_Expression
(N
) then
3429 Apply_Compile_Time_Constraint_Error
3430 (N
, "string literal too long for}", CE_Length_Check_Failed
,
3432 Typ
=> First_Subtype
(Bas
));
3434 Apply_Compile_Time_Constraint_Error
3435 (N
, "string value too long for}", CE_Length_Check_Failed
,
3437 Typ
=> First_Subtype
(Bas
),
3441 -- Test for null string not allowed
3444 and then not Is_Generic_Type
(Xtp
)
3446 Expr_Value
(Lo
) = Expr_Value
(Type_Low_Bound
(Base_Type
(Xtp
)))
3448 -- Same specialization of message
3450 if Is_Static_Expression
(N
) then
3451 Apply_Compile_Time_Constraint_Error
3452 (N
, "null string literal not allowed for}",
3453 CE_Length_Check_Failed
,
3455 Typ
=> First_Subtype
(Bas
));
3457 Apply_Compile_Time_Constraint_Error
3458 (N
, "null string value not allowed for}",
3459 CE_Length_Check_Failed
,
3461 Typ
=> First_Subtype
(Bas
),
3466 end Eval_String_Literal
;
3468 --------------------------
3469 -- Eval_Type_Conversion --
3470 --------------------------
3472 -- A type conversion is potentially static if its subtype mark is for a
3473 -- static scalar subtype, and its operand expression is potentially static
3476 procedure Eval_Type_Conversion
(N
: Node_Id
) is
3477 Operand
: constant Node_Id
:= Expression
(N
);
3478 Source_Type
: constant Entity_Id
:= Etype
(Operand
);
3479 Target_Type
: constant Entity_Id
:= Etype
(N
);
3484 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean;
3485 -- Returns true if type T is an integer type, or if it is a fixed-point
3486 -- type to be treated as an integer (i.e. the flag Conversion_OK is set
3487 -- on the conversion node).
3489 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean;
3490 -- Returns true if type T is a floating-point type, or if it is a
3491 -- fixed-point type that is not to be treated as an integer (i.e. the
3492 -- flag Conversion_OK is not set on the conversion node).
3494 ------------------------------
3495 -- To_Be_Treated_As_Integer --
3496 ------------------------------
3498 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean is
3502 or else (Is_Fixed_Point_Type
(T
) and then Conversion_OK
(N
));
3503 end To_Be_Treated_As_Integer
;
3505 ---------------------------
3506 -- To_Be_Treated_As_Real --
3507 ---------------------------
3509 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean is
3512 Is_Floating_Point_Type
(T
)
3513 or else (Is_Fixed_Point_Type
(T
) and then not Conversion_OK
(N
));
3514 end To_Be_Treated_As_Real
;
3516 -- Start of processing for Eval_Type_Conversion
3519 -- Cannot fold if target type is non-static or if semantic error
3521 if not Is_Static_Subtype
(Target_Type
) then
3522 Check_Non_Static_Context
(Operand
);
3525 elsif Error_Posted
(N
) then
3529 -- If not foldable we are done
3531 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
3536 -- Don't try fold if target type has constraint error bounds
3538 elsif not Is_OK_Static_Subtype
(Target_Type
) then
3539 Set_Raises_Constraint_Error
(N
);
3543 -- Remaining processing depends on operand types. Note that in the
3544 -- following type test, fixed-point counts as real unless the flag
3545 -- Conversion_OK is set, in which case it counts as integer.
3547 -- Fold conversion, case of string type. The result is not static
3549 if Is_String_Type
(Target_Type
) then
3550 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Static
=> False);
3554 -- Fold conversion, case of integer target type
3556 elsif To_Be_Treated_As_Integer
(Target_Type
) then
3561 -- Integer to integer conversion
3563 if To_Be_Treated_As_Integer
(Source_Type
) then
3564 Result
:= Expr_Value
(Operand
);
3566 -- Real to integer conversion
3569 Result
:= UR_To_Uint
(Expr_Value_R
(Operand
));
3572 -- If fixed-point type (Conversion_OK must be set), then the
3573 -- result is logically an integer, but we must replace the
3574 -- conversion with the corresponding real literal, since the
3575 -- type from a semantic point of view is still fixed-point.
3577 if Is_Fixed_Point_Type
(Target_Type
) then
3579 (N
, UR_From_Uint
(Result
) * Small_Value
(Target_Type
), Stat
);
3581 -- Otherwise result is integer literal
3584 Fold_Uint
(N
, Result
, Stat
);
3588 -- Fold conversion, case of real target type
3590 elsif To_Be_Treated_As_Real
(Target_Type
) then
3595 if To_Be_Treated_As_Real
(Source_Type
) then
3596 Result
:= Expr_Value_R
(Operand
);
3598 Result
:= UR_From_Uint
(Expr_Value
(Operand
));
3601 Fold_Ureal
(N
, Result
, Stat
);
3604 -- Enumeration types
3607 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
3610 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
3614 end Eval_Type_Conversion
;
3620 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
3621 -- are potentially static if the operand is potentially static (RM 4.9(7)).
3623 procedure Eval_Unary_Op
(N
: Node_Id
) is
3624 Right
: constant Node_Id
:= Right_Opnd
(N
);
3625 Otype
: Entity_Id
:= Empty
;
3630 -- If not foldable we are done
3632 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
3638 if Etype
(Right
) = Universal_Integer
3640 Etype
(Right
) = Universal_Real
3642 Otype
:= Find_Universal_Operator_Type
(N
);
3645 -- Fold for integer case
3647 if Is_Integer_Type
(Etype
(N
)) then
3649 Rint
: constant Uint
:= Expr_Value
(Right
);
3653 -- In the case of modular unary plus and abs there is no need
3654 -- to adjust the result of the operation since if the original
3655 -- operand was in bounds the result will be in the bounds of the
3656 -- modular type. However, in the case of modular unary minus the
3657 -- result may go out of the bounds of the modular type and needs
3660 if Nkind
(N
) = N_Op_Plus
then
3663 elsif Nkind
(N
) = N_Op_Minus
then
3664 if Is_Modular_Integer_Type
(Etype
(N
)) then
3665 Result
:= (-Rint
) mod Modulus
(Etype
(N
));
3671 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
3675 Fold_Uint
(N
, Result
, Stat
);
3678 -- Fold for real case
3680 elsif Is_Real_Type
(Etype
(N
)) then
3682 Rreal
: constant Ureal
:= Expr_Value_R
(Right
);
3686 if Nkind
(N
) = N_Op_Plus
then
3689 elsif Nkind
(N
) = N_Op_Minus
then
3690 Result
:= UR_Negate
(Rreal
);
3693 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
3694 Result
:= abs Rreal
;
3697 Fold_Ureal
(N
, Result
, Stat
);
3701 -- If the operator was resolved to a specific type, make sure that type
3702 -- is frozen even if the expression is folded into a literal (which has
3703 -- a universal type).
3705 if Present
(Otype
) then
3706 Freeze_Before
(N
, Otype
);
3710 -------------------------------
3711 -- Eval_Unchecked_Conversion --
3712 -------------------------------
3714 -- Unchecked conversions can never be static, so the only required
3715 -- processing is to check for a non-static context for the operand.
3717 procedure Eval_Unchecked_Conversion
(N
: Node_Id
) is
3719 Check_Non_Static_Context
(Expression
(N
));
3720 end Eval_Unchecked_Conversion
;
3722 --------------------
3723 -- Expr_Rep_Value --
3724 --------------------
3726 function Expr_Rep_Value
(N
: Node_Id
) return Uint
is
3727 Kind
: constant Node_Kind
:= Nkind
(N
);
3731 if Is_Entity_Name
(N
) then
3734 -- An enumeration literal that was either in the source or created
3735 -- as a result of static evaluation.
3737 if Ekind
(Ent
) = E_Enumeration_Literal
then
3738 return Enumeration_Rep
(Ent
);
3740 -- A user defined static constant
3743 pragma Assert
(Ekind
(Ent
) = E_Constant
);
3744 return Expr_Rep_Value
(Constant_Value
(Ent
));
3747 -- An integer literal that was either in the source or created as a
3748 -- result of static evaluation.
3750 elsif Kind
= N_Integer_Literal
then
3753 -- A real literal for a fixed-point type. This must be the fixed-point
3754 -- case, either the literal is of a fixed-point type, or it is a bound
3755 -- of a fixed-point type, with type universal real. In either case we
3756 -- obtain the desired value from Corresponding_Integer_Value.
3758 elsif Kind
= N_Real_Literal
then
3759 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
3760 return Corresponding_Integer_Value
(N
);
3762 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3764 elsif Kind
= N_Attribute_Reference
3765 and then Attribute_Name
(N
) = Name_Null_Parameter
3769 -- Otherwise must be character literal
3772 pragma Assert
(Kind
= N_Character_Literal
);
3775 -- Since Character literals of type Standard.Character don't have any
3776 -- defining character literals built for them, they do not have their
3777 -- Entity set, so just use their Char code. Otherwise for user-
3778 -- defined character literals use their Pos value as usual which is
3779 -- the same as the Rep value.
3782 return Char_Literal_Value
(N
);
3784 return Enumeration_Rep
(Ent
);
3793 function Expr_Value
(N
: Node_Id
) return Uint
is
3794 Kind
: constant Node_Kind
:= Nkind
(N
);
3795 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(N
) mod CV_Cache_Size
);
3800 -- If already in cache, then we know it's compile time known and we can
3801 -- return the value that was previously stored in the cache since
3802 -- compile time known values cannot change.
3804 if CV_Ent
.N
= N
then
3808 -- Otherwise proceed to test value
3810 if Is_Entity_Name
(N
) then
3813 -- An enumeration literal that was either in the source or created as
3814 -- a result of static evaluation.
3816 if Ekind
(Ent
) = E_Enumeration_Literal
then
3817 Val
:= Enumeration_Pos
(Ent
);
3819 -- A user defined static constant
3822 pragma Assert
(Ekind
(Ent
) = E_Constant
);
3823 Val
:= Expr_Value
(Constant_Value
(Ent
));
3826 -- An integer literal that was either in the source or created as a
3827 -- result of static evaluation.
3829 elsif Kind
= N_Integer_Literal
then
3832 -- A real literal for a fixed-point type. This must be the fixed-point
3833 -- case, either the literal is of a fixed-point type, or it is a bound
3834 -- of a fixed-point type, with type universal real. In either case we
3835 -- obtain the desired value from Corresponding_Integer_Value.
3837 elsif Kind
= N_Real_Literal
then
3839 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
3840 Val
:= Corresponding_Integer_Value
(N
);
3842 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3844 elsif Kind
= N_Attribute_Reference
3845 and then Attribute_Name
(N
) = Name_Null_Parameter
3849 -- Otherwise must be character literal
3852 pragma Assert
(Kind
= N_Character_Literal
);
3855 -- Since Character literals of type Standard.Character don't
3856 -- have any defining character literals built for them, they
3857 -- do not have their Entity set, so just use their Char
3858 -- code. Otherwise for user-defined character literals use
3859 -- their Pos value as usual.
3862 Val
:= Char_Literal_Value
(N
);
3864 Val
:= Enumeration_Pos
(Ent
);
3868 -- Come here with Val set to value to be returned, set cache
3879 function Expr_Value_E
(N
: Node_Id
) return Entity_Id
is
3880 Ent
: constant Entity_Id
:= Entity
(N
);
3883 if Ekind
(Ent
) = E_Enumeration_Literal
then
3886 pragma Assert
(Ekind
(Ent
) = E_Constant
);
3887 return Expr_Value_E
(Constant_Value
(Ent
));
3895 function Expr_Value_R
(N
: Node_Id
) return Ureal
is
3896 Kind
: constant Node_Kind
:= Nkind
(N
);
3900 if Kind
= N_Real_Literal
then
3903 elsif Kind
= N_Identifier
or else Kind
= N_Expanded_Name
then
3905 pragma Assert
(Ekind
(Ent
) = E_Constant
);
3906 return Expr_Value_R
(Constant_Value
(Ent
));
3908 elsif Kind
= N_Integer_Literal
then
3909 return UR_From_Uint
(Expr_Value
(N
));
3911 -- Peculiar VMS case, if we have xxx'Null_Parameter, return 0.0
3913 elsif Kind
= N_Attribute_Reference
3914 and then Attribute_Name
(N
) = Name_Null_Parameter
3919 -- If we fall through, we have a node that cannot be interpreted as a
3920 -- compile time constant. That is definitely an error.
3922 raise Program_Error
;
3929 function Expr_Value_S
(N
: Node_Id
) return Node_Id
is
3931 if Nkind
(N
) = N_String_Literal
then
3934 pragma Assert
(Ekind
(Entity
(N
)) = E_Constant
);
3935 return Expr_Value_S
(Constant_Value
(Entity
(N
)));
3939 ----------------------------------
3940 -- Find_Universal_Operator_Type --
3941 ----------------------------------
3943 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
is
3944 PN
: constant Node_Id
:= Parent
(N
);
3945 Call
: constant Node_Id
:= Original_Node
(N
);
3946 Is_Int
: constant Boolean := Is_Integer_Type
(Etype
(N
));
3948 Is_Fix
: constant Boolean :=
3949 Nkind
(N
) in N_Binary_Op
3950 and then Nkind
(Right_Opnd
(N
)) /= Nkind
(Left_Opnd
(N
));
3951 -- A mixed-mode operation in this context indicates the presence of
3952 -- fixed-point type in the designated package.
3954 Is_Relational
: constant Boolean := Etype
(N
) = Standard_Boolean
;
3955 -- Case where N is a relational (or membership) operator (else it is an
3958 In_Membership
: constant Boolean :=
3959 Nkind
(PN
) in N_Membership_Test
3961 Nkind
(Right_Opnd
(PN
)) = N_Range
3963 Is_Universal_Numeric_Type
(Etype
(Left_Opnd
(PN
)))
3965 Is_Universal_Numeric_Type
3966 (Etype
(Low_Bound
(Right_Opnd
(PN
))))
3968 Is_Universal_Numeric_Type
3969 (Etype
(High_Bound
(Right_Opnd
(PN
))));
3970 -- Case where N is part of a membership test with a universal range
3974 Typ1
: Entity_Id
:= Empty
;
3977 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean;
3978 -- Check whether one operand is a mixed-mode operation that requires the
3979 -- presence of a fixed-point type. Given that all operands are universal
3980 -- and have been constant-folded, retrieve the original function call.
3982 ---------------------------
3983 -- Is_Mixed_Mode_Operand --
3984 ---------------------------
3986 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean is
3987 Onod
: constant Node_Id
:= Original_Node
(Op
);
3989 return Nkind
(Onod
) = N_Function_Call
3990 and then Present
(Next_Actual
(First_Actual
(Onod
)))
3991 and then Etype
(First_Actual
(Onod
)) /=
3992 Etype
(Next_Actual
(First_Actual
(Onod
)));
3993 end Is_Mixed_Mode_Operand
;
3995 -- Start of processing for Find_Universal_Operator_Type
3998 if Nkind
(Call
) /= N_Function_Call
3999 or else Nkind
(Name
(Call
)) /= N_Expanded_Name
4003 -- There are several cases where the context does not imply the type of
4005 -- - the universal expression appears in a type conversion;
4006 -- - the expression is a relational operator applied to universal
4008 -- - the expression is a membership test with a universal operand
4009 -- and a range with universal bounds.
4011 elsif Nkind
(Parent
(N
)) = N_Type_Conversion
4012 or else Is_Relational
4013 or else In_Membership
4015 Pack
:= Entity
(Prefix
(Name
(Call
)));
4017 -- If the prefix is a package declared elsewhere, iterate over its
4018 -- visible entities, otherwise iterate over all declarations in the
4019 -- designated scope.
4021 if Ekind
(Pack
) = E_Package
4022 and then not In_Open_Scopes
(Pack
)
4024 Priv_E
:= First_Private_Entity
(Pack
);
4030 E
:= First_Entity
(Pack
);
4031 while Present
(E
) and then E
/= Priv_E
loop
4032 if Is_Numeric_Type
(E
)
4033 and then Nkind
(Parent
(E
)) /= N_Subtype_Declaration
4034 and then Comes_From_Source
(E
)
4035 and then Is_Integer_Type
(E
) = Is_Int
4037 (Nkind
(N
) in N_Unary_Op
4038 or else Is_Relational
4039 or else Is_Fixed_Point_Type
(E
) = Is_Fix
)
4044 -- Before emitting an error, check for the presence of a
4045 -- mixed-mode operation that specifies a fixed point type.
4049 (Is_Mixed_Mode_Operand
(Left_Opnd
(N
))
4050 or else Is_Mixed_Mode_Operand
(Right_Opnd
(N
)))
4051 and then Is_Fixed_Point_Type
(E
) /= Is_Fixed_Point_Type
(Typ1
)
4054 if Is_Fixed_Point_Type
(E
) then
4059 -- More than one type of the proper class declared in P
4061 Error_Msg_N
("ambiguous operation", N
);
4062 Error_Msg_Sloc
:= Sloc
(Typ1
);
4063 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4064 Error_Msg_Sloc
:= Sloc
(E
);
4065 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4075 end Find_Universal_Operator_Type
;
4077 --------------------------
4078 -- Flag_Non_Static_Expr --
4079 --------------------------
4081 procedure Flag_Non_Static_Expr
(Msg
: String; Expr
: Node_Id
) is
4083 if Error_Posted
(Expr
) and then not All_Errors_Mode
then
4086 Error_Msg_F
(Msg
, Expr
);
4087 Why_Not_Static
(Expr
);
4089 end Flag_Non_Static_Expr
;
4095 procedure Fold_Str
(N
: Node_Id
; Val
: String_Id
; Static
: Boolean) is
4096 Loc
: constant Source_Ptr
:= Sloc
(N
);
4097 Typ
: constant Entity_Id
:= Etype
(N
);
4100 Rewrite
(N
, Make_String_Literal
(Loc
, Strval
=> Val
));
4102 -- We now have the literal with the right value, both the actual type
4103 -- and the expected type of this literal are taken from the expression
4104 -- that was evaluated. So now we do the Analyze and Resolve.
4106 -- Note that we have to reset Is_Static_Expression both after the
4107 -- analyze step (because Resolve will evaluate the literal, which
4108 -- will cause semantic errors if it is marked as static), and after
4109 -- the Resolve step (since Resolve in some cases resets this flag).
4112 Set_Is_Static_Expression
(N
, Static
);
4115 Set_Is_Static_Expression
(N
, Static
);
4122 procedure Fold_Uint
(N
: Node_Id
; Val
: Uint
; Static
: Boolean) is
4123 Loc
: constant Source_Ptr
:= Sloc
(N
);
4124 Typ
: Entity_Id
:= Etype
(N
);
4128 -- If we are folding a named number, retain the entity in the literal,
4131 if Is_Entity_Name
(N
)
4132 and then Ekind
(Entity
(N
)) = E_Named_Integer
4139 if Is_Private_Type
(Typ
) then
4140 Typ
:= Full_View
(Typ
);
4143 -- For a result of type integer, substitute an N_Integer_Literal node
4144 -- for the result of the compile time evaluation of the expression.
4145 -- For ASIS use, set a link to the original named number when not in
4146 -- a generic context.
4148 if Is_Integer_Type
(Typ
) then
4149 Rewrite
(N
, Make_Integer_Literal
(Loc
, Val
));
4151 Set_Original_Entity
(N
, Ent
);
4153 -- Otherwise we have an enumeration type, and we substitute either
4154 -- an N_Identifier or N_Character_Literal to represent the enumeration
4155 -- literal corresponding to the given value, which must always be in
4156 -- range, because appropriate tests have already been made for this.
4158 else pragma Assert
(Is_Enumeration_Type
(Typ
));
4159 Rewrite
(N
, Get_Enum_Lit_From_Pos
(Etype
(N
), Val
, Loc
));
4162 -- We now have the literal with the right value, both the actual type
4163 -- and the expected type of this literal are taken from the expression
4164 -- that was evaluated. So now we do the Analyze and Resolve.
4166 -- Note that we have to reset Is_Static_Expression both after the
4167 -- analyze step (because Resolve will evaluate the literal, which
4168 -- will cause semantic errors if it is marked as static), and after
4169 -- the Resolve step (since Resolve in some cases sets this flag).
4172 Set_Is_Static_Expression
(N
, Static
);
4175 Set_Is_Static_Expression
(N
, Static
);
4182 procedure Fold_Ureal
(N
: Node_Id
; Val
: Ureal
; Static
: Boolean) is
4183 Loc
: constant Source_Ptr
:= Sloc
(N
);
4184 Typ
: constant Entity_Id
:= Etype
(N
);
4188 -- If we are folding a named number, retain the entity in the literal,
4191 if Is_Entity_Name
(N
)
4192 and then Ekind
(Entity
(N
)) = E_Named_Real
4199 Rewrite
(N
, Make_Real_Literal
(Loc
, Realval
=> Val
));
4201 -- Set link to original named number, for ASIS use
4203 Set_Original_Entity
(N
, Ent
);
4205 -- We now have the literal with the right value, both the actual type
4206 -- and the expected type of this literal are taken from the expression
4207 -- that was evaluated. So now we do the Analyze and Resolve.
4209 -- Note that we have to reset Is_Static_Expression both after the
4210 -- analyze step (because Resolve will evaluate the literal, which
4211 -- will cause semantic errors if it is marked as static), and after
4212 -- the Resolve step (since Resolve in some cases sets this flag).
4215 Set_Is_Static_Expression
(N
, Static
);
4218 Set_Is_Static_Expression
(N
, Static
);
4225 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
is
4229 for J
in 0 .. B
'Last loop
4235 if Non_Binary_Modulus
(T
) then
4236 V
:= V
mod Modulus
(T
);
4242 --------------------
4243 -- Get_String_Val --
4244 --------------------
4246 function Get_String_Val
(N
: Node_Id
) return Node_Id
is
4248 if Nkind
(N
) = N_String_Literal
then
4251 elsif Nkind
(N
) = N_Character_Literal
then
4255 pragma Assert
(Is_Entity_Name
(N
));
4256 return Get_String_Val
(Constant_Value
(Entity
(N
)));
4264 procedure Initialize
is
4266 CV_Cache
:= (others => (Node_High_Bound
, Uint_0
));
4269 --------------------
4270 -- In_Subrange_Of --
4271 --------------------
4273 function In_Subrange_Of
4276 Fixed_Int
: Boolean := False) return Boolean
4285 if T1
= T2
or else Is_Subtype_Of
(T1
, T2
) then
4288 -- Never in range if both types are not scalar. Don't know if this can
4289 -- actually happen, but just in case.
4291 elsif not Is_Scalar_Type
(T1
) or else not Is_Scalar_Type
(T2
) then
4294 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
4295 -- definitely not compatible with T2.
4297 elsif Is_Floating_Point_Type
(T1
)
4298 and then Has_Infinities
(T1
)
4299 and then Is_Floating_Point_Type
(T2
)
4300 and then not Has_Infinities
(T2
)
4305 L1
:= Type_Low_Bound
(T1
);
4306 H1
:= Type_High_Bound
(T1
);
4308 L2
:= Type_Low_Bound
(T2
);
4309 H2
:= Type_High_Bound
(T2
);
4311 -- Check bounds to see if comparison possible at compile time
4313 if Compile_Time_Compare
(L1
, L2
, Assume_Valid
=> True) in Compare_GE
4315 Compile_Time_Compare
(H1
, H2
, Assume_Valid
=> True) in Compare_LE
4320 -- If bounds not comparable at compile time, then the bounds of T2
4321 -- must be compile time known or we cannot answer the query.
4323 if not Compile_Time_Known_Value
(L2
)
4324 or else not Compile_Time_Known_Value
(H2
)
4329 -- If the bounds of T1 are know at compile time then use these
4330 -- ones, otherwise use the bounds of the base type (which are of
4331 -- course always static).
4333 if not Compile_Time_Known_Value
(L1
) then
4334 L1
:= Type_Low_Bound
(Base_Type
(T1
));
4337 if not Compile_Time_Known_Value
(H1
) then
4338 H1
:= Type_High_Bound
(Base_Type
(T1
));
4341 -- Fixed point types should be considered as such only if
4342 -- flag Fixed_Int is set to False.
4344 if Is_Floating_Point_Type
(T1
) or else Is_Floating_Point_Type
(T2
)
4345 or else (Is_Fixed_Point_Type
(T1
) and then not Fixed_Int
)
4346 or else (Is_Fixed_Point_Type
(T2
) and then not Fixed_Int
)
4349 Expr_Value_R
(L2
) <= Expr_Value_R
(L1
)
4351 Expr_Value_R
(H2
) >= Expr_Value_R
(H1
);
4355 Expr_Value
(L2
) <= Expr_Value
(L1
)
4357 Expr_Value
(H2
) >= Expr_Value
(H1
);
4362 -- If any exception occurs, it means that we have some bug in the compiler
4363 -- possibly triggered by a previous error, or by some unforeseen peculiar
4364 -- occurrence. However, this is only an optimization attempt, so there is
4365 -- really no point in crashing the compiler. Instead we just decide, too
4366 -- bad, we can't figure out the answer in this case after all.
4371 -- Debug flag K disables this behavior (useful for debugging)
4373 if Debug_Flag_K
then
4384 function Is_In_Range
4387 Assume_Valid
: Boolean := False;
4388 Fixed_Int
: Boolean := False;
4389 Int_Real
: Boolean := False) return Boolean
4392 return Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
)
4400 function Is_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
4401 Typ
: constant Entity_Id
:= Etype
(Lo
);
4404 if not Compile_Time_Known_Value
(Lo
)
4405 or else not Compile_Time_Known_Value
(Hi
)
4410 if Is_Discrete_Type
(Typ
) then
4411 return Expr_Value
(Lo
) > Expr_Value
(Hi
);
4414 pragma Assert
(Is_Real_Type
(Typ
));
4415 return Expr_Value_R
(Lo
) > Expr_Value_R
(Hi
);
4419 -----------------------------
4420 -- Is_OK_Static_Expression --
4421 -----------------------------
4423 function Is_OK_Static_Expression
(N
: Node_Id
) return Boolean is
4425 return Is_Static_Expression
(N
)
4426 and then not Raises_Constraint_Error
(N
);
4427 end Is_OK_Static_Expression
;
4429 ------------------------
4430 -- Is_OK_Static_Range --
4431 ------------------------
4433 -- A static range is a range whose bounds are static expressions, or a
4434 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4435 -- We have already converted range attribute references, so we get the
4436 -- "or" part of this rule without needing a special test.
4438 function Is_OK_Static_Range
(N
: Node_Id
) return Boolean is
4440 return Is_OK_Static_Expression
(Low_Bound
(N
))
4441 and then Is_OK_Static_Expression
(High_Bound
(N
));
4442 end Is_OK_Static_Range
;
4444 --------------------------
4445 -- Is_OK_Static_Subtype --
4446 --------------------------
4448 -- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
4449 -- neither bound raises constraint error when evaluated.
4451 function Is_OK_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
4452 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
4453 Anc_Subt
: Entity_Id
;
4456 -- First a quick check on the non static subtype flag. As described
4457 -- in further detail in Einfo, this flag is not decisive in all cases,
4458 -- but if it is set, then the subtype is definitely non-static.
4460 if Is_Non_Static_Subtype
(Typ
) then
4464 Anc_Subt
:= Ancestor_Subtype
(Typ
);
4466 if Anc_Subt
= Empty
then
4470 if Is_Generic_Type
(Root_Type
(Base_T
))
4471 or else Is_Generic_Actual_Type
(Base_T
)
4477 elsif Is_String_Type
(Typ
) then
4479 Ekind
(Typ
) = E_String_Literal_Subtype
4481 (Is_OK_Static_Subtype
(Component_Type
(Typ
))
4482 and then Is_OK_Static_Subtype
(Etype
(First_Index
(Typ
))));
4486 elsif Is_Scalar_Type
(Typ
) then
4487 if Base_T
= Typ
then
4491 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
4492 -- Get_Type_{Low,High}_Bound.
4494 return Is_OK_Static_Subtype
(Anc_Subt
)
4495 and then Is_OK_Static_Expression
(Type_Low_Bound
(Typ
))
4496 and then Is_OK_Static_Expression
(Type_High_Bound
(Typ
));
4499 -- Types other than string and scalar types are never static
4504 end Is_OK_Static_Subtype
;
4506 ---------------------
4507 -- Is_Out_Of_Range --
4508 ---------------------
4510 function Is_Out_Of_Range
4513 Assume_Valid
: Boolean := False;
4514 Fixed_Int
: Boolean := False;
4515 Int_Real
: Boolean := False) return Boolean
4518 return Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
)
4520 end Is_Out_Of_Range
;
4522 ---------------------
4523 -- Is_Static_Range --
4524 ---------------------
4526 -- A static range is a range whose bounds are static expressions, or a
4527 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4528 -- We have already converted range attribute references, so we get the
4529 -- "or" part of this rule without needing a special test.
4531 function Is_Static_Range
(N
: Node_Id
) return Boolean is
4533 return Is_Static_Expression
(Low_Bound
(N
))
4534 and then Is_Static_Expression
(High_Bound
(N
));
4535 end Is_Static_Range
;
4537 -----------------------
4538 -- Is_Static_Subtype --
4539 -----------------------
4541 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
4543 function Is_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
4544 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
4545 Anc_Subt
: Entity_Id
;
4548 -- First a quick check on the non static subtype flag. As described
4549 -- in further detail in Einfo, this flag is not decisive in all cases,
4550 -- but if it is set, then the subtype is definitely non-static.
4552 if Is_Non_Static_Subtype
(Typ
) then
4556 Anc_Subt
:= Ancestor_Subtype
(Typ
);
4558 if Anc_Subt
= Empty
then
4562 if Is_Generic_Type
(Root_Type
(Base_T
))
4563 or else Is_Generic_Actual_Type
(Base_T
)
4569 elsif Is_String_Type
(Typ
) then
4571 Ekind
(Typ
) = E_String_Literal_Subtype
4572 or else (Is_Static_Subtype
(Component_Type
(Typ
))
4573 and then Is_Static_Subtype
(Etype
(First_Index
(Typ
))));
4577 elsif Is_Scalar_Type
(Typ
) then
4578 if Base_T
= Typ
then
4582 return Is_Static_Subtype
(Anc_Subt
)
4583 and then Is_Static_Expression
(Type_Low_Bound
(Typ
))
4584 and then Is_Static_Expression
(Type_High_Bound
(Typ
));
4587 -- Types other than string and scalar types are never static
4592 end Is_Static_Subtype
;
4594 --------------------
4595 -- Not_Null_Range --
4596 --------------------
4598 function Not_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
4599 Typ
: constant Entity_Id
:= Etype
(Lo
);
4602 if not Compile_Time_Known_Value
(Lo
)
4603 or else not Compile_Time_Known_Value
(Hi
)
4608 if Is_Discrete_Type
(Typ
) then
4609 return Expr_Value
(Lo
) <= Expr_Value
(Hi
);
4612 pragma Assert
(Is_Real_Type
(Typ
));
4614 return Expr_Value_R
(Lo
) <= Expr_Value_R
(Hi
);
4622 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean is
4624 -- We allow a maximum of 500,000 bits which seems a reasonable limit
4626 if Bits
< 500_000
then
4630 Error_Msg_N
("static value too large, capacity exceeded", N
);
4639 procedure Out_Of_Range
(N
: Node_Id
) is
4641 -- If we have the static expression case, then this is an illegality
4642 -- in Ada 95 mode, except that in an instance, we never generate an
4643 -- error (if the error is legitimate, it was already diagnosed in the
4644 -- template). The expression to compute the length of a packed array is
4645 -- attached to the array type itself, and deserves a separate message.
4647 if Is_Static_Expression
(N
)
4648 and then not In_Instance
4649 and then not In_Inlined_Body
4650 and then Ada_Version
>= Ada_95
4652 if Nkind
(Parent
(N
)) = N_Defining_Identifier
4653 and then Is_Array_Type
(Parent
(N
))
4654 and then Present
(Packed_Array_Type
(Parent
(N
)))
4655 and then Present
(First_Rep_Item
(Parent
(N
)))
4658 ("length of packed array must not exceed Integer''Last",
4659 First_Rep_Item
(Parent
(N
)));
4660 Rewrite
(N
, Make_Integer_Literal
(Sloc
(N
), Uint_1
));
4663 Apply_Compile_Time_Constraint_Error
4664 (N
, "value not in range of}", CE_Range_Check_Failed
);
4667 -- Here we generate a warning for the Ada 83 case, or when we are in an
4668 -- instance, or when we have a non-static expression case.
4671 Apply_Compile_Time_Constraint_Error
4672 (N
, "value not in range of}??", CE_Range_Check_Failed
);
4676 -------------------------
4677 -- Rewrite_In_Raise_CE --
4678 -------------------------
4680 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
) is
4681 Typ
: constant Entity_Id
:= Etype
(N
);
4684 -- If we want to raise CE in the condition of a N_Raise_CE node
4685 -- we may as well get rid of the condition.
4687 if Present
(Parent
(N
))
4688 and then Nkind
(Parent
(N
)) = N_Raise_Constraint_Error
4690 Set_Condition
(Parent
(N
), Empty
);
4692 -- If the expression raising CE is a N_Raise_CE node, we can use that
4693 -- one. We just preserve the type of the context.
4695 elsif Nkind
(Exp
) = N_Raise_Constraint_Error
then
4699 -- Else build an explcit N_Raise_CE
4703 Make_Raise_Constraint_Error
(Sloc
(Exp
),
4704 Reason
=> CE_Range_Check_Failed
));
4705 Set_Raises_Constraint_Error
(N
);
4708 end Rewrite_In_Raise_CE
;
4710 ---------------------
4711 -- String_Type_Len --
4712 ---------------------
4714 function String_Type_Len
(Stype
: Entity_Id
) return Uint
is
4715 NT
: constant Entity_Id
:= Etype
(First_Index
(Stype
));
4719 if Is_OK_Static_Subtype
(NT
) then
4722 T
:= Base_Type
(NT
);
4725 return Expr_Value
(Type_High_Bound
(T
)) -
4726 Expr_Value
(Type_Low_Bound
(T
)) + 1;
4727 end String_Type_Len
;
4729 ------------------------------------
4730 -- Subtypes_Statically_Compatible --
4731 ------------------------------------
4733 function Subtypes_Statically_Compatible
4735 T2
: Entity_Id
) return Boolean
4740 if Is_Scalar_Type
(T1
) then
4742 -- Definitely compatible if we match
4744 if Subtypes_Statically_Match
(T1
, T2
) then
4747 -- If either subtype is nonstatic then they're not compatible
4749 elsif not Is_Static_Subtype
(T1
)
4750 or else not Is_Static_Subtype
(T2
)
4754 -- If either type has constraint error bounds, then consider that
4755 -- they match to avoid junk cascaded errors here.
4757 elsif not Is_OK_Static_Subtype
(T1
)
4758 or else not Is_OK_Static_Subtype
(T2
)
4762 -- Base types must match, but we don't check that (should we???) but
4763 -- we do at least check that both types are real, or both types are
4766 elsif Is_Real_Type
(T1
) /= Is_Real_Type
(T2
) then
4769 -- Here we check the bounds
4773 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
4774 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
4775 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
4776 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
4779 if Is_Real_Type
(T1
) then
4781 (Expr_Value_R
(LB1
) > Expr_Value_R
(HB1
))
4783 (Expr_Value_R
(LB2
) <= Expr_Value_R
(LB1
)
4785 Expr_Value_R
(HB1
) <= Expr_Value_R
(HB2
));
4789 (Expr_Value
(LB1
) > Expr_Value
(HB1
))
4791 (Expr_Value
(LB2
) <= Expr_Value
(LB1
)
4793 Expr_Value
(HB1
) <= Expr_Value
(HB2
));
4800 elsif Is_Access_Type
(T1
) then
4801 return (not Is_Constrained
(T2
)
4802 or else (Subtypes_Statically_Match
4803 (Designated_Type
(T1
), Designated_Type
(T2
))))
4804 and then not (Can_Never_Be_Null
(T2
)
4805 and then not Can_Never_Be_Null
(T1
));
4810 return (Is_Composite_Type
(T1
) and then not Is_Constrained
(T2
))
4811 or else Subtypes_Statically_Match
(T1
, T2
);
4813 end Subtypes_Statically_Compatible
;
4815 -------------------------------
4816 -- Subtypes_Statically_Match --
4817 -------------------------------
4819 -- Subtypes statically match if they have statically matching constraints
4820 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
4821 -- they are the same identical constraint, or if they are static and the
4822 -- values match (RM 4.9.1(1)).
4824 function Subtypes_Statically_Match
(T1
, T2
: Entity_Id
) return Boolean is
4826 function Predicates_Match
return Boolean;
4827 -- In Ada 2012, subtypes statically match if their static predicates
4830 ----------------------
4831 -- Predicates_Match --
4832 ----------------------
4834 function Predicates_Match
return Boolean is
4839 if Ada_Version
< Ada_2012
then
4842 elsif Has_Predicates
(T1
) /= Has_Predicates
(T2
) then
4848 (T1
, Name_Static_Predicate
, Check_Parents
=> False);
4851 (T2
, Name_Static_Predicate
, Check_Parents
=> False);
4853 -- Subtypes statically match if the predicate comes from the
4854 -- same declaration, which can only happen if one is a subtype
4855 -- of the other and has no explicit predicate.
4857 -- Suppress warnings on order of actuals, which is otherwise
4858 -- triggered by one of the two calls below.
4860 pragma Warnings
(Off
);
4861 return Pred1
= Pred2
4862 or else (No
(Pred1
) and then Is_Subtype_Of
(T1
, T2
))
4863 or else (No
(Pred2
) and then Is_Subtype_Of
(T2
, T1
));
4864 pragma Warnings
(On
);
4866 end Predicates_Match
;
4868 -- Start of processing for Subtypes_Statically_Match
4871 -- A type always statically matches itself
4878 elsif Is_Scalar_Type
(T1
) then
4880 -- Base types must be the same
4882 if Base_Type
(T1
) /= Base_Type
(T2
) then
4886 -- A constrained numeric subtype never matches an unconstrained
4887 -- subtype, i.e. both types must be constrained or unconstrained.
4889 -- To understand the requirement for this test, see RM 4.9.1(1).
4890 -- As is made clear in RM 3.5.4(11), type Integer, for example is
4891 -- a constrained subtype with constraint bounds matching the bounds
4892 -- of its corresponding unconstrained base type. In this situation,
4893 -- Integer and Integer'Base do not statically match, even though
4894 -- they have the same bounds.
4896 -- We only apply this test to types in Standard and types that appear
4897 -- in user programs. That way, we do not have to be too careful about
4898 -- setting Is_Constrained right for Itypes.
4900 if Is_Numeric_Type
(T1
)
4901 and then (Is_Constrained
(T1
) /= Is_Constrained
(T2
))
4902 and then (Scope
(T1
) = Standard_Standard
4903 or else Comes_From_Source
(T1
))
4904 and then (Scope
(T2
) = Standard_Standard
4905 or else Comes_From_Source
(T2
))
4909 -- A generic scalar type does not statically match its base type
4910 -- (AI-311). In this case we make sure that the formals, which are
4911 -- first subtypes of their bases, are constrained.
4913 elsif Is_Generic_Type
(T1
)
4914 and then Is_Generic_Type
(T2
)
4915 and then (Is_Constrained
(T1
) /= Is_Constrained
(T2
))
4920 -- If there was an error in either range, then just assume the types
4921 -- statically match to avoid further junk errors.
4923 if No
(Scalar_Range
(T1
)) or else No
(Scalar_Range
(T2
))
4924 or else Error_Posted
(Scalar_Range
(T1
))
4925 or else Error_Posted
(Scalar_Range
(T2
))
4930 -- Otherwise both types have bound that can be compared
4933 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
4934 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
4935 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
4936 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
4939 -- If the bounds are the same tree node, then match if and only
4940 -- if any predicates present also match.
4942 if LB1
= LB2
and then HB1
= HB2
then
4943 return Predicates_Match
;
4945 -- Otherwise bounds must be static and identical value
4948 if not Is_Static_Subtype
(T1
)
4949 or else not Is_Static_Subtype
(T2
)
4953 -- If either type has constraint error bounds, then say that
4954 -- they match to avoid junk cascaded errors here.
4956 elsif not Is_OK_Static_Subtype
(T1
)
4957 or else not Is_OK_Static_Subtype
(T2
)
4961 elsif Is_Real_Type
(T1
) then
4963 (Expr_Value_R
(LB1
) = Expr_Value_R
(LB2
))
4965 (Expr_Value_R
(HB1
) = Expr_Value_R
(HB2
));
4969 Expr_Value
(LB1
) = Expr_Value
(LB2
)
4971 Expr_Value
(HB1
) = Expr_Value
(HB2
);
4976 -- Type with discriminants
4978 elsif Has_Discriminants
(T1
) or else Has_Discriminants
(T2
) then
4980 -- Because of view exchanges in multiple instantiations, conformance
4981 -- checking might try to match a partial view of a type with no
4982 -- discriminants with a full view that has defaulted discriminants.
4983 -- In such a case, use the discriminant constraint of the full view,
4984 -- which must exist because we know that the two subtypes have the
4987 if Has_Discriminants
(T1
) /= Has_Discriminants
(T2
) then
4989 if Is_Private_Type
(T2
)
4990 and then Present
(Full_View
(T2
))
4991 and then Has_Discriminants
(Full_View
(T2
))
4993 return Subtypes_Statically_Match
(T1
, Full_View
(T2
));
4995 elsif Is_Private_Type
(T1
)
4996 and then Present
(Full_View
(T1
))
4997 and then Has_Discriminants
(Full_View
(T1
))
4999 return Subtypes_Statically_Match
(Full_View
(T1
), T2
);
5010 DL1
: constant Elist_Id
:= Discriminant_Constraint
(T1
);
5011 DL2
: constant Elist_Id
:= Discriminant_Constraint
(T2
);
5019 elsif Is_Constrained
(T1
) /= Is_Constrained
(T2
) then
5023 -- Now loop through the discriminant constraints
5025 -- Note: the guard here seems necessary, since it is possible at
5026 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
5028 if Present
(DL1
) and then Present
(DL2
) then
5029 DA1
:= First_Elmt
(DL1
);
5030 DA2
:= First_Elmt
(DL2
);
5031 while Present
(DA1
) loop
5033 Expr1
: constant Node_Id
:= Node
(DA1
);
5034 Expr2
: constant Node_Id
:= Node
(DA2
);
5037 if not Is_Static_Expression
(Expr1
)
5038 or else not Is_Static_Expression
(Expr2
)
5042 -- If either expression raised a constraint error,
5043 -- consider the expressions as matching, since this
5044 -- helps to prevent cascading errors.
5046 elsif Raises_Constraint_Error
(Expr1
)
5047 or else Raises_Constraint_Error
(Expr2
)
5051 elsif Expr_Value
(Expr1
) /= Expr_Value
(Expr2
) then
5064 -- A definite type does not match an indefinite or classwide type.
5065 -- However, a generic type with unknown discriminants may be
5066 -- instantiated with a type with no discriminants, and conformance
5067 -- checking on an inherited operation may compare the actual with the
5068 -- subtype that renames it in the instance.
5071 Has_Unknown_Discriminants
(T1
) /= Has_Unknown_Discriminants
(T2
)
5074 Is_Generic_Actual_Type
(T1
) or else Is_Generic_Actual_Type
(T2
);
5078 elsif Is_Array_Type
(T1
) then
5080 -- If either subtype is unconstrained then both must be, and if both
5081 -- are unconstrained then no further checking is needed.
5083 if not Is_Constrained
(T1
) or else not Is_Constrained
(T2
) then
5084 return not (Is_Constrained
(T1
) or else Is_Constrained
(T2
));
5087 -- Both subtypes are constrained, so check that the index subtypes
5088 -- statically match.
5091 Index1
: Node_Id
:= First_Index
(T1
);
5092 Index2
: Node_Id
:= First_Index
(T2
);
5095 while Present
(Index1
) loop
5097 Subtypes_Statically_Match
(Etype
(Index1
), Etype
(Index2
))
5102 Next_Index
(Index1
);
5103 Next_Index
(Index2
);
5109 elsif Is_Access_Type
(T1
) then
5110 if Can_Never_Be_Null
(T1
) /= Can_Never_Be_Null
(T2
) then
5113 elsif Ekind_In
(T1
, E_Access_Subprogram_Type
,
5114 E_Anonymous_Access_Subprogram_Type
)
5118 (Designated_Type
(T1
),
5119 Designated_Type
(T2
));
5122 Subtypes_Statically_Match
5123 (Designated_Type
(T1
),
5124 Designated_Type
(T2
))
5125 and then Is_Access_Constant
(T1
) = Is_Access_Constant
(T2
);
5128 -- All other types definitely match
5133 end Subtypes_Statically_Match
;
5139 function Test
(Cond
: Boolean) return Uint
is
5148 ---------------------------------
5149 -- Test_Expression_Is_Foldable --
5150 ---------------------------------
5154 procedure Test_Expression_Is_Foldable
5164 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
5168 -- If operand is Any_Type, just propagate to result and do not
5169 -- try to fold, this prevents cascaded errors.
5171 if Etype
(Op1
) = Any_Type
then
5172 Set_Etype
(N
, Any_Type
);
5175 -- If operand raises constraint error, then replace node N with the
5176 -- raise constraint error node, and we are obviously not foldable.
5177 -- Note that this replacement inherits the Is_Static_Expression flag
5178 -- from the operand.
5180 elsif Raises_Constraint_Error
(Op1
) then
5181 Rewrite_In_Raise_CE
(N
, Op1
);
5184 -- If the operand is not static, then the result is not static, and
5185 -- all we have to do is to check the operand since it is now known
5186 -- to appear in a non-static context.
5188 elsif not Is_Static_Expression
(Op1
) then
5189 Check_Non_Static_Context
(Op1
);
5190 Fold
:= Compile_Time_Known_Value
(Op1
);
5193 -- An expression of a formal modular type is not foldable because
5194 -- the modulus is unknown.
5196 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
5197 and then Is_Generic_Type
(Etype
(Op1
))
5199 Check_Non_Static_Context
(Op1
);
5202 -- Here we have the case of an operand whose type is OK, which is
5203 -- static, and which does not raise constraint error, we can fold.
5206 Set_Is_Static_Expression
(N
);
5210 end Test_Expression_Is_Foldable
;
5214 procedure Test_Expression_Is_Foldable
5221 Rstat
: constant Boolean := Is_Static_Expression
(Op1
)
5222 and then Is_Static_Expression
(Op2
);
5228 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
5232 -- If either operand is Any_Type, just propagate to result and
5233 -- do not try to fold, this prevents cascaded errors.
5235 if Etype
(Op1
) = Any_Type
or else Etype
(Op2
) = Any_Type
then
5236 Set_Etype
(N
, Any_Type
);
5239 -- If left operand raises constraint error, then replace node N with the
5240 -- Raise_Constraint_Error node, and we are obviously not foldable.
5241 -- Is_Static_Expression is set from the two operands in the normal way,
5242 -- and we check the right operand if it is in a non-static context.
5244 elsif Raises_Constraint_Error
(Op1
) then
5246 Check_Non_Static_Context
(Op2
);
5249 Rewrite_In_Raise_CE
(N
, Op1
);
5250 Set_Is_Static_Expression
(N
, Rstat
);
5253 -- Similar processing for the case of the right operand. Note that we
5254 -- don't use this routine for the short-circuit case, so we do not have
5255 -- to worry about that special case here.
5257 elsif Raises_Constraint_Error
(Op2
) then
5259 Check_Non_Static_Context
(Op1
);
5262 Rewrite_In_Raise_CE
(N
, Op2
);
5263 Set_Is_Static_Expression
(N
, Rstat
);
5266 -- Exclude expressions of a generic modular type, as above
5268 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
5269 and then Is_Generic_Type
(Etype
(Op1
))
5271 Check_Non_Static_Context
(Op1
);
5274 -- If result is not static, then check non-static contexts on operands
5275 -- since one of them may be static and the other one may not be static.
5277 elsif not Rstat
then
5278 Check_Non_Static_Context
(Op1
);
5279 Check_Non_Static_Context
(Op2
);
5280 Fold
:= Compile_Time_Known_Value
(Op1
)
5281 and then Compile_Time_Known_Value
(Op2
);
5284 -- Else result is static and foldable. Both operands are static, and
5285 -- neither raises constraint error, so we can definitely fold.
5288 Set_Is_Static_Expression
(N
);
5293 end Test_Expression_Is_Foldable
;
5299 function Test_In_Range
5302 Assume_Valid
: Boolean;
5303 Fixed_Int
: Boolean;
5304 Int_Real
: Boolean) return Range_Membership
5309 pragma Warnings
(Off
, Assume_Valid
);
5310 -- For now Assume_Valid is unreferenced since the current implementation
5311 -- always returns Unknown if N is not a compile time known value, but we
5312 -- keep the parameter to allow for future enhancements in which we try
5313 -- to get the information in the variable case as well.
5316 -- Universal types have no range limits, so always in range
5318 if Typ
= Universal_Integer
or else Typ
= Universal_Real
then
5321 -- Never known if not scalar type. Don't know if this can actually
5322 -- happen, but our spec allows it, so we must check!
5324 elsif not Is_Scalar_Type
(Typ
) then
5327 -- Never known if this is a generic type, since the bounds of generic
5328 -- types are junk. Note that if we only checked for static expressions
5329 -- (instead of compile time known values) below, we would not need this
5330 -- check, because values of a generic type can never be static, but they
5331 -- can be known at compile time.
5333 elsif Is_Generic_Type
(Typ
) then
5336 -- Never known unless we have a compile time known value
5338 elsif not Compile_Time_Known_Value
(N
) then
5341 -- General processing with a known compile time value
5352 Lo
:= Type_Low_Bound
(Typ
);
5353 Hi
:= Type_High_Bound
(Typ
);
5355 LB_Known
:= Compile_Time_Known_Value
(Lo
);
5356 HB_Known
:= Compile_Time_Known_Value
(Hi
);
5358 -- Fixed point types should be considered as such only if flag
5359 -- Fixed_Int is set to False.
5361 if Is_Floating_Point_Type
(Typ
)
5362 or else (Is_Fixed_Point_Type
(Typ
) and then not Fixed_Int
)
5365 Valr
:= Expr_Value_R
(N
);
5367 if LB_Known
and HB_Known
then
5368 if Valr
>= Expr_Value_R
(Lo
)
5370 Valr
<= Expr_Value_R
(Hi
)
5374 return Out_Of_Range
;
5377 elsif (LB_Known
and then Valr
< Expr_Value_R
(Lo
))
5379 (HB_Known
and then Valr
> Expr_Value_R
(Hi
))
5381 return Out_Of_Range
;
5388 Val
:= Expr_Value
(N
);
5390 if LB_Known
and HB_Known
then
5391 if Val
>= Expr_Value
(Lo
)
5393 Val
<= Expr_Value
(Hi
)
5397 return Out_Of_Range
;
5400 elsif (LB_Known
and then Val
< Expr_Value
(Lo
))
5402 (HB_Known
and then Val
> Expr_Value
(Hi
))
5404 return Out_Of_Range
;
5418 procedure To_Bits
(U
: Uint
; B
: out Bits
) is
5420 for J
in 0 .. B
'Last loop
5421 B
(J
) := (U
/ (2 ** J
)) mod 2 /= 0;
5425 --------------------
5426 -- Why_Not_Static --
5427 --------------------
5429 procedure Why_Not_Static
(Expr
: Node_Id
) is
5430 N
: constant Node_Id
:= Original_Node
(Expr
);
5434 procedure Why_Not_Static_List
(L
: List_Id
);
5435 -- A version that can be called on a list of expressions. Finds all
5436 -- non-static violations in any element of the list.
5438 -------------------------
5439 -- Why_Not_Static_List --
5440 -------------------------
5442 procedure Why_Not_Static_List
(L
: List_Id
) is
5446 if Is_Non_Empty_List
(L
) then
5448 while Present
(N
) loop
5453 end Why_Not_Static_List
;
5455 -- Start of processing for Why_Not_Static
5458 -- If in ACATS mode (debug flag 2), then suppress all these messages,
5459 -- this avoids massive updates to the ACATS base line.
5461 if Debug_Flag_2
then
5465 -- Ignore call on error or empty node
5467 if No
(Expr
) or else Nkind
(Expr
) = N_Error
then
5471 -- Preprocessing for sub expressions
5473 if Nkind
(Expr
) in N_Subexpr
then
5475 -- Nothing to do if expression is static
5477 if Is_OK_Static_Expression
(Expr
) then
5481 -- Test for constraint error raised
5483 if Raises_Constraint_Error
(Expr
) then
5485 ("\expression raises exception, cannot be static " &
5490 -- If no type, then something is pretty wrong, so ignore
5492 Typ
:= Etype
(Expr
);
5498 -- Type must be scalar or string type (but allow Bignum, since this
5499 -- is really a scalar type from our point of view in this diagnosis).
5501 if not Is_Scalar_Type
(Typ
)
5502 and then not Is_String_Type
(Typ
)
5503 and then not Is_RTE
(Typ
, RE_Bignum
)
5506 ("\static expression must have scalar or string type " &
5512 -- If we got through those checks, test particular node kind
5518 when N_Expanded_Name | N_Identifier | N_Operator_Symbol
=>
5521 if Is_Named_Number
(E
) then
5524 elsif Ekind
(E
) = E_Constant
then
5526 -- One case we can give a metter message is when we have a
5527 -- string literal created by concatenating an aggregate with
5528 -- an others expression.
5530 Entity_Case
: declare
5531 CV
: constant Node_Id
:= Constant_Value
(E
);
5532 CO
: constant Node_Id
:= Original_Node
(CV
);
5534 function Is_Aggregate
(N
: Node_Id
) return Boolean;
5535 -- See if node N came from an others aggregate, if so
5536 -- return True and set Error_Msg_Sloc to aggregate.
5542 function Is_Aggregate
(N
: Node_Id
) return Boolean is
5544 if Nkind
(Original_Node
(N
)) = N_Aggregate
then
5545 Error_Msg_Sloc
:= Sloc
(Original_Node
(N
));
5547 elsif Is_Entity_Name
(N
)
5548 and then Ekind
(Entity
(N
)) = E_Constant
5550 Nkind
(Original_Node
(Constant_Value
(Entity
(N
)))) =
5554 Sloc
(Original_Node
(Constant_Value
(Entity
(N
))));
5561 -- Start of processing for Entity_Case
5564 if Is_Aggregate
(CV
)
5565 or else (Nkind
(CO
) = N_Op_Concat
5566 and then (Is_Aggregate
(Left_Opnd
(CO
))
5568 Is_Aggregate
(Right_Opnd
(CO
))))
5570 Error_Msg_N
("\aggregate (#) is never static", N
);
5572 elsif No
(CV
) or else not Is_Static_Expression
(CV
) then
5574 ("\& is not a static constant (RM 4.9(5))", N
, E
);
5580 ("\& is not static constant or named number "
5581 & "(RM 4.9(5))", N
, E
);
5586 when N_Binary_Op | N_Short_Circuit | N_Membership_Test
=>
5587 if Nkind
(N
) in N_Op_Shift
then
5589 ("\shift functions are never static (RM 4.9(6,18))", N
);
5592 Why_Not_Static
(Left_Opnd
(N
));
5593 Why_Not_Static
(Right_Opnd
(N
));
5599 Why_Not_Static
(Right_Opnd
(N
));
5601 -- Attribute reference
5603 when N_Attribute_Reference
=>
5604 Why_Not_Static_List
(Expressions
(N
));
5606 E
:= Etype
(Prefix
(N
));
5608 if E
= Standard_Void_Type
then
5612 -- Special case non-scalar'Size since this is a common error
5614 if Attribute_Name
(N
) = Name_Size
then
5616 ("\size attribute is only static for static scalar type "
5617 & "(RM 4.9(7,8))", N
);
5621 elsif Is_Array_Type
(E
) then
5622 if Attribute_Name
(N
) /= Name_First
5624 Attribute_Name
(N
) /= Name_Last
5626 Attribute_Name
(N
) /= Name_Length
5629 ("\static array attribute must be Length, First, or Last "
5630 & "(RM 4.9(8))", N
);
5632 -- Since we know the expression is not-static (we already
5633 -- tested for this, must mean array is not static).
5637 ("\prefix is non-static array (RM 4.9(8))", Prefix
(N
));
5642 -- Special case generic types, since again this is a common source
5645 elsif Is_Generic_Actual_Type
(E
)
5650 ("\attribute of generic type is never static "
5651 & "(RM 4.9(7,8))", N
);
5653 elsif Is_Static_Subtype
(E
) then
5656 elsif Is_Scalar_Type
(E
) then
5658 ("\prefix type for attribute is not static scalar subtype "
5659 & "(RM 4.9(7))", N
);
5663 ("\static attribute must apply to array/scalar type "
5664 & "(RM 4.9(7,8))", N
);
5669 when N_String_Literal
=>
5671 ("\subtype of string literal is non-static (RM 4.9(4))", N
);
5673 -- Explicit dereference
5675 when N_Explicit_Dereference
=>
5677 ("\explicit dereference is never static (RM 4.9)", N
);
5681 when N_Function_Call
=>
5682 Why_Not_Static_List
(Parameter_Associations
(N
));
5684 -- Complain about non-static function call unless we have Bignum
5685 -- which means that the underlying expression is really some
5686 -- scalar arithmetic operation.
5688 if not Is_RTE
(Typ
, RE_Bignum
) then
5689 Error_Msg_N
("\non-static function call (RM 4.9(6,18))", N
);
5692 -- Parameter assocation (test actual parameter)
5694 when N_Parameter_Association
=>
5695 Why_Not_Static
(Explicit_Actual_Parameter
(N
));
5697 -- Indexed component
5699 when N_Indexed_Component
=>
5700 Error_Msg_N
("\indexed component is never static (RM 4.9)", N
);
5704 when N_Procedure_Call_Statement
=>
5705 Error_Msg_N
("\procedure call is never static (RM 4.9)", N
);
5707 -- Qualified expression (test expression)
5709 when N_Qualified_Expression
=>
5710 Why_Not_Static
(Expression
(N
));
5714 when N_Aggregate | N_Extension_Aggregate
=>
5715 Error_Msg_N
("\an aggregate is never static (RM 4.9)", N
);
5720 Why_Not_Static
(Low_Bound
(N
));
5721 Why_Not_Static
(High_Bound
(N
));
5723 -- Range constraint, test range expression
5725 when N_Range_Constraint
=>
5726 Why_Not_Static
(Range_Expression
(N
));
5728 -- Subtype indication, test constraint
5730 when N_Subtype_Indication
=>
5731 Why_Not_Static
(Constraint
(N
));
5733 -- Selected component
5735 when N_Selected_Component
=>
5736 Error_Msg_N
("\selected component is never static (RM 4.9)", N
);
5741 Error_Msg_N
("\slice is never static (RM 4.9)", N
);
5743 when N_Type_Conversion
=>
5744 Why_Not_Static
(Expression
(N
));
5746 if not Is_Scalar_Type
(Entity
(Subtype_Mark
(N
)))
5747 or else not Is_Static_Subtype
(Entity
(Subtype_Mark
(N
)))
5750 ("\static conversion requires static scalar subtype result "
5751 & "(RM 4.9(9))", N
);
5754 -- Unchecked type conversion
5756 when N_Unchecked_Type_Conversion
=>
5758 ("\unchecked type conversion is never static (RM 4.9)", N
);
5760 -- All other cases, no reason to give