1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2014, 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 Par_SCO
; use Par_SCO
;
41 with Rtsfind
; use Rtsfind
;
43 with Sem_Aux
; use Sem_Aux
;
44 with Sem_Cat
; use Sem_Cat
;
45 with Sem_Ch6
; use Sem_Ch6
;
46 with Sem_Ch8
; use Sem_Ch8
;
47 with Sem_Res
; use Sem_Res
;
48 with Sem_Util
; use Sem_Util
;
49 with Sem_Type
; use Sem_Type
;
50 with Sem_Warn
; use Sem_Warn
;
51 with Sinfo
; use Sinfo
;
52 with Snames
; use Snames
;
53 with Stand
; use Stand
;
54 with Stringt
; use Stringt
;
55 with Tbuild
; use Tbuild
;
57 package body Sem_Eval
is
59 -----------------------------------------
60 -- Handling of Compile Time Evaluation --
61 -----------------------------------------
63 -- The compile time evaluation of expressions is distributed over several
64 -- Eval_xxx procedures. These procedures are called immediately after
65 -- a subexpression is resolved and is therefore accomplished in a bottom
66 -- up fashion. The flags are synthesized using the following approach.
68 -- Is_Static_Expression is determined by following the detailed rules
69 -- in RM 4.9(4-14). This involves testing the Is_Static_Expression
70 -- flag of the operands in many cases.
72 -- Raises_Constraint_Error is set if any of the operands have the flag
73 -- set or if an attempt to compute the value of the current expression
74 -- results in detection of a runtime constraint error.
76 -- As described in the spec, the requirement is that Is_Static_Expression
77 -- be accurately set, and in addition for nodes for which this flag is set,
78 -- Raises_Constraint_Error must also be set. Furthermore a node which has
79 -- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
80 -- requirement is that the expression value must be precomputed, and the
81 -- node is either a literal, or the name of a constant entity whose value
82 -- is a static expression.
84 -- The general approach is as follows. First compute Is_Static_Expression.
85 -- If the node is not static, then the flag is left off in the node and
86 -- we are all done. Otherwise for a static node, we test if any of the
87 -- operands will raise constraint error, and if so, propagate the flag
88 -- Raises_Constraint_Error to the result node and we are done (since the
89 -- error was already posted at a lower level).
91 -- For the case of a static node whose operands do not raise constraint
92 -- error, we attempt to evaluate the node. If this evaluation succeeds,
93 -- then the node is replaced by the result of this computation. If the
94 -- evaluation raises constraint error, then we rewrite the node with
95 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
96 -- to post appropriate error messages.
102 type Bits
is array (Nat
range <>) of Boolean;
103 -- Used to convert unsigned (modular) values for folding logical ops
105 -- The following declarations are used to maintain a cache of nodes that
106 -- have compile time known values. The cache is maintained only for
107 -- discrete types (the most common case), and is populated by calls to
108 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
109 -- since it is possible for the status to change (in particular it is
110 -- possible for a node to get replaced by a constraint error node).
112 CV_Bits
: constant := 5;
113 -- Number of low order bits of Node_Id value used to reference entries
114 -- in the cache table.
116 CV_Cache_Size
: constant Nat
:= 2 ** CV_Bits
;
117 -- Size of cache for compile time values
119 subtype CV_Range
is Nat
range 0 .. CV_Cache_Size
;
121 type CV_Entry
is record
126 type Match_Result
is (Match
, No_Match
, Non_Static
);
127 -- Result returned from functions that test for a matching result. If the
128 -- operands are not OK_Static then Non_Static will be returned. Otherwise
129 -- Match/No_Match is returned depending on whether the match succeeds.
131 type CV_Cache_Array
is array (CV_Range
) of CV_Entry
;
133 CV_Cache
: CV_Cache_Array
:= (others => (Node_High_Bound
, Uint_0
));
134 -- This is the actual cache, with entries consisting of node/value pairs,
135 -- and the impossible value Node_High_Bound used for unset entries.
137 type Range_Membership
is (In_Range
, Out_Of_Range
, Unknown
);
138 -- Range membership may either be statically known to be in range or out
139 -- of range, or not statically known. Used for Test_In_Range below.
141 -----------------------
142 -- Local Subprograms --
143 -----------------------
145 function Choice_Matches
147 Choice
: Node_Id
) return Match_Result
;
148 -- Determines whether given value Expr matches the given Choice. The Expr
149 -- can be of discrete, real, or string type and must be a compile time
150 -- known value (it is an error to make the call if these conditions are
151 -- not met). The choice can be a range, subtype name, subtype indication,
152 -- or expression. The returned result is Non_Static if Choice is not
153 -- OK_Static, otherwise either Match or No_Match is returned depending
154 -- on whether Choice matches Expr. This is used for case expression
155 -- alternatives, and also for membership tests. In each case, more
156 -- possibilities are tested than the syntax allows (e.g. membership allows
157 -- subtype indications and non-discrete types, and case allows an OTHERS
158 -- choice), but it does not matter, since we have already done a full
159 -- semantic and syntax check of the construct, so the extra possibilities
160 -- just will not arise for correct expressions.
162 -- Note: if Choice_Matches finds that a choice raises Constraint_Error, e.g
163 -- a reference to a type, one of whose bounds raises Constraint_Error, then
164 -- it also sets the Raises_Constraint_Error flag on the Choice itself.
166 function Choices_Match
168 Choices
: List_Id
) return Match_Result
;
169 -- This function applies Choice_Matches to each element of Choices. If the
170 -- result is No_Match, then it continues and checks the next element. If
171 -- the result is Match or Non_Static, this result is immediately given
172 -- as the result without checking the rest of the list. Expr can be of
173 -- discrete, real, or string type and must be a compile time known value
174 -- (it is an error to make the call if these conditions are not met).
176 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
;
177 -- Converts a bit string of length B'Length to a Uint value to be used for
178 -- a target of type T, which is a modular type. This procedure includes the
179 -- necessary reduction by the modulus in the case of a non-binary modulus
180 -- (for a binary modulus, the bit string is the right length any way so all
183 function Is_Static_Choice
(Choice
: Node_Id
) return Boolean;
184 -- Given a choice (from a case expression or membership test), returns
185 -- True if the choice is static. No test is made for raising of constraint
186 -- error, so this function is used only for legality tests.
188 function Is_Static_Choice_List
(Choices
: List_Id
) return Boolean;
189 -- Given a choice list (from a case expression or membership test), return
190 -- True if all choices are static in the sense of Is_Static_Choice.
192 function Is_OK_Static_Choice
(Choice
: Node_Id
) return Boolean;
193 -- Given a choice (from a case expression or membership test), returns
194 -- True if the choice is static and does not raise a Constraint_Error.
196 function Is_OK_Static_Choice_List
(Choices
: List_Id
) return Boolean;
197 -- Given a choice list (from a case expression or membership test), return
198 -- True if all choices are static in the sense of Is_OK_Static_Choice.
200 function Is_Static_Range
(N
: Node_Id
) return Boolean;
201 -- Determine if range is static, as defined in RM 4.9(26). The only allowed
202 -- argument is an N_Range node (but note that the semantic analysis of
203 -- equivalent range attribute references already turned them into the
204 -- equivalent range). This differs from Is_OK_Static_Range (which is what
205 -- must be used by clients) in that it does not care whether the bounds
206 -- raise Constraint_Error or not. Used for checking whether expressions are
207 -- static in the 4.9 sense (without worrying about exceptions).
209 function Get_String_Val
(N
: Node_Id
) return Node_Id
;
210 -- Given a tree node for a folded string or character value, returns the
211 -- corresponding string literal or character literal (one of the two must
212 -- be available, or the operand would not have been marked as foldable in
213 -- the earlier analysis of the operation).
215 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean;
216 -- Bits represents the number of bits in an integer value to be computed
217 -- (but the value has not been computed yet). If this value in Bits is
218 -- reasonable, a result of True is returned, with the implication that the
219 -- caller should go ahead and complete the calculation. If the value in
220 -- Bits is unreasonably large, then an error is posted on node N, and
221 -- False is returned (and the caller skips the proposed calculation).
223 procedure Out_Of_Range
(N
: Node_Id
);
224 -- This procedure is called if it is determined that node N, which appears
225 -- in a non-static context, is a compile time known value which is outside
226 -- its range, i.e. the range of Etype. This is used in contexts where
227 -- this is an illegality if N is static, and should generate a warning
230 function Real_Or_String_Static_Predicate_Matches
232 Typ
: Entity_Id
) return Boolean;
233 -- This is the function used to evaluate real or string static predicates.
234 -- Val is an unanalyzed N_Real_Literal or N_String_Literal node, which
235 -- represents the value to be tested against the predicate. Typ is the
236 -- type with the predicate, from which the predicate expression can be
237 -- extracted. The result returned is True if the given value satisfies
240 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
);
241 -- N and Exp are nodes representing an expression, Exp is known to raise
242 -- CE. N is rewritten in term of Exp in the optimal way.
244 function String_Type_Len
(Stype
: Entity_Id
) return Uint
;
245 -- Given a string type, determines the length of the index type, or, if
246 -- this index type is non-static, the length of the base type of this index
247 -- type. Note that if the string type is itself static, then the index type
248 -- is static, so the second case applies only if the string type passed is
251 function Test
(Cond
: Boolean) return Uint
;
252 pragma Inline
(Test
);
253 -- This function simply returns the appropriate Boolean'Pos value
254 -- corresponding to the value of Cond as a universal integer. It is
255 -- used for producing the result of the static evaluation of the
258 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
;
259 -- Check whether an arithmetic operation with universal operands which is a
260 -- rewritten function call with an explicit scope indication is ambiguous:
261 -- P."+" (1, 2) will be ambiguous if there is more than one visible numeric
262 -- type declared in P and the context does not impose a type on the result
263 -- (e.g. in the expression of a type conversion). If ambiguous, emit an
264 -- error and return Empty, else return the result type of the operator.
266 procedure Test_Expression_Is_Foldable
271 -- Tests to see if expression N whose single operand is Op1 is foldable,
272 -- i.e. the operand value is known at compile time. If the operation is
273 -- foldable, then Fold is True on return, and Stat indicates whether the
274 -- result is static (i.e. the operand was static). Note that it is quite
275 -- possible for Fold to be True, and Stat to be False, since there are
276 -- cases in which we know the value of an operand even though it is not
277 -- technically static (e.g. the static lower bound of a range whose upper
278 -- bound is non-static).
280 -- If Stat is set False on return, then Test_Expression_Is_Foldable makes
281 -- a call to Check_Non_Static_Context on the operand. If Fold is False on
282 -- return, then all processing is complete, and the caller should return,
283 -- since there is nothing else to do.
285 -- If Stat is set True on return, then Is_Static_Expression is also set
286 -- true in node N. There are some cases where this is over-enthusiastic,
287 -- e.g. in the two operand case below, for string comparison, the result is
288 -- not static even though the two operands are static. In such cases, the
289 -- caller must reset the Is_Static_Expression flag in N.
291 -- If Fold and Stat are both set to False then this routine performs also
292 -- the following extra actions:
294 -- If either operand is Any_Type then propagate it to result to prevent
297 -- If some operand raises constraint error, then replace the node N
298 -- with the raise constraint error node. This replacement inherits the
299 -- Is_Static_Expression flag from the operands.
301 procedure Test_Expression_Is_Foldable
307 CRT_Safe
: Boolean := False);
308 -- Same processing, except applies to an expression N with two operands
309 -- Op1 and Op2. The result is static only if both operands are static. If
310 -- CRT_Safe is set True, then CRT_Safe_Compile_Time_Known_Value is used
311 -- for the tests that the two operands are known at compile time. See
312 -- spec of this routine for further details.
314 function Test_In_Range
317 Assume_Valid
: Boolean;
319 Int_Real
: Boolean) return Range_Membership
;
320 -- Common processing for Is_In_Range and Is_Out_Of_Range: Returns In_Range
321 -- or Out_Of_Range if it can be guaranteed at compile time that expression
322 -- N is known to be in or out of range of the subtype Typ. If not compile
323 -- time known, Unknown is returned. See documentation of Is_In_Range for
324 -- complete description of parameters.
326 procedure To_Bits
(U
: Uint
; B
: out Bits
);
327 -- Converts a Uint value to a bit string of length B'Length
329 -----------------------------------------------
330 -- Check_Expression_Against_Static_Predicate --
331 -----------------------------------------------
333 procedure Check_Expression_Against_Static_Predicate
338 -- Nothing to do if expression is not known at compile time, or the
339 -- type has no static predicate set (will be the case for all non-scalar
340 -- types, so no need to make a special test for that).
342 if not (Has_Static_Predicate
(Typ
)
343 and then Compile_Time_Known_Value
(Expr
))
348 -- Here we have a static predicate (note that it could have arisen from
349 -- an explicitly specified Dynamic_Predicate whose expression met the
350 -- rules for being predicate-static).
352 -- Case of real static predicate
354 if Is_Real_Type
(Typ
) then
355 if Real_Or_String_Static_Predicate_Matches
356 (Val
=> Make_Real_Literal
(Sloc
(Expr
), Expr_Value_R
(Expr
)),
362 -- Case of string static predicate
364 elsif Is_String_Type
(Typ
) then
365 if Real_Or_String_Static_Predicate_Matches
366 (Val
=> Expr_Value_S
(Expr
), Typ
=> Typ
)
371 -- Case of discrete static predicate
374 pragma Assert
(Is_Discrete_Type
(Typ
));
376 -- If static predicate matches, nothing to do
378 if Choices_Match
(Expr
, Static_Discrete_Predicate
(Typ
)) = Match
then
383 -- Here we know that the predicate will fail
385 -- Special case of static expression failing a predicate (other than one
386 -- that was explicitly specified with a Dynamic_Predicate aspect). This
387 -- is the case where the expression is no longer considered static.
389 if Is_Static_Expression
(Expr
)
390 and then not Has_Dynamic_Predicate_Aspect
(Typ
)
393 ("??static expression fails static predicate check on &",
396 ("\??expression is no longer considered static", Expr
);
397 Set_Is_Static_Expression
(Expr
, False);
399 -- In all other cases, this is just a warning that a test will fail.
400 -- It does not matter if the expression is static or not, or if the
401 -- predicate comes from a dynamic predicate aspect or not.
405 ("??expression fails predicate check on &", Expr
, Typ
);
407 end Check_Expression_Against_Static_Predicate
;
409 ------------------------------
410 -- Check_Non_Static_Context --
411 ------------------------------
413 procedure Check_Non_Static_Context
(N
: Node_Id
) is
414 T
: constant Entity_Id
:= Etype
(N
);
415 Checks_On
: constant Boolean :=
416 not Index_Checks_Suppressed
(T
)
417 and not Range_Checks_Suppressed
(T
);
420 -- Ignore cases of non-scalar types, error types, or universal real
421 -- types that have no usable bounds.
424 or else not Is_Scalar_Type
(T
)
425 or else T
= Universal_Fixed
426 or else T
= Universal_Real
431 -- At this stage we have a scalar type. If we have an expression that
432 -- raises CE, then we already issued a warning or error msg so there is
433 -- nothing more to be done in this routine.
435 if Raises_Constraint_Error
(N
) then
439 -- Now we have a scalar type which is not marked as raising a constraint
440 -- error exception. The main purpose of this routine is to deal with
441 -- static expressions appearing in a non-static context. That means
442 -- that if we do not have a static expression then there is not much
443 -- to do. The one case that we deal with here is that if we have a
444 -- floating-point value that is out of range, then we post a warning
445 -- that an infinity will result.
447 if not Is_Static_Expression
(N
) then
448 if Is_Floating_Point_Type
(T
)
449 and then Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True)
452 ("??float value out of range, infinity will be generated", N
);
458 -- Here we have the case of outer level static expression of scalar
459 -- type, where the processing of this procedure is needed.
461 -- For real types, this is where we convert the value to a machine
462 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should only
463 -- need to do this if the parent is a constant declaration, since in
464 -- other cases, gigi should do the necessary conversion correctly, but
465 -- experimentation shows that this is not the case on all machines, in
466 -- particular if we do not convert all literals to machine values in
467 -- non-static contexts, then ACVC test C490001 fails on Sparc/Solaris
470 if Nkind
(N
) = N_Real_Literal
471 and then not Is_Machine_Number
(N
)
472 and then not Is_Generic_Type
(Etype
(N
))
473 and then Etype
(N
) /= Universal_Real
475 -- Check that value is in bounds before converting to machine
476 -- number, so as not to lose case where value overflows in the
477 -- least significant bit or less. See B490001.
479 if Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
484 -- Note: we have to copy the node, to avoid problems with conformance
485 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
487 Rewrite
(N
, New_Copy
(N
));
489 if not Is_Floating_Point_Type
(T
) then
491 (N
, Corresponding_Integer_Value
(N
) * Small_Value
(T
));
493 elsif not UR_Is_Zero
(Realval
(N
)) then
495 -- Note: even though RM 4.9(38) specifies biased rounding, this
496 -- has been modified by AI-100 in order to prevent confusing
497 -- differences in rounding between static and non-static
498 -- expressions. AI-100 specifies that the effect of such rounding
499 -- is implementation dependent, and in GNAT we round to nearest
500 -- even to match the run-time behavior.
503 (N
, Machine
(Base_Type
(T
), Realval
(N
), Round_Even
, N
));
506 Set_Is_Machine_Number
(N
);
509 -- Check for out of range universal integer. This is a non-static
510 -- context, so the integer value must be in range of the runtime
511 -- representation of universal integers.
513 -- We do this only within an expression, because that is the only
514 -- case in which non-static universal integer values can occur, and
515 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
516 -- called in contexts like the expression of a number declaration where
517 -- we certainly want to allow out of range values.
519 if Etype
(N
) = Universal_Integer
520 and then Nkind
(N
) = N_Integer_Literal
521 and then Nkind
(Parent
(N
)) in N_Subexpr
523 (Intval
(N
) < Expr_Value
(Type_Low_Bound
(Universal_Integer
))
525 Intval
(N
) > Expr_Value
(Type_High_Bound
(Universal_Integer
)))
527 Apply_Compile_Time_Constraint_Error
528 (N
, "non-static universal integer value out of range<<",
529 CE_Range_Check_Failed
);
531 -- Check out of range of base type
533 elsif Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True) then
536 -- Give warning if outside subtype (where one or both of the bounds of
537 -- the subtype is static). This warning is omitted if the expression
538 -- appears in a range that could be null (warnings are handled elsewhere
541 elsif T
/= Base_Type
(T
) and then Nkind
(Parent
(N
)) /= N_Range
then
542 if Is_In_Range
(N
, T
, Assume_Valid
=> True) then
545 elsif Is_Out_Of_Range
(N
, T
, Assume_Valid
=> True) then
546 Apply_Compile_Time_Constraint_Error
547 (N
, "value not in range of}<<", CE_Range_Check_Failed
);
550 Enable_Range_Check
(N
);
553 Set_Do_Range_Check
(N
, False);
556 end Check_Non_Static_Context
;
558 ---------------------------------
559 -- Check_String_Literal_Length --
560 ---------------------------------
562 procedure Check_String_Literal_Length
(N
: Node_Id
; Ttype
: Entity_Id
) is
564 if not Raises_Constraint_Error
(N
) and then Is_Constrained
(Ttype
) then
565 if UI_From_Int
(String_Length
(Strval
(N
))) /= String_Type_Len
(Ttype
)
567 Apply_Compile_Time_Constraint_Error
568 (N
, "string length wrong for}??",
569 CE_Length_Check_Failed
,
574 end Check_String_Literal_Length
;
580 function Choice_Matches
582 Choice
: Node_Id
) return Match_Result
584 Etyp
: constant Entity_Id
:= Etype
(Expr
);
590 pragma Assert
(Compile_Time_Known_Value
(Expr
));
591 pragma Assert
(Is_Scalar_Type
(Etyp
) or else Is_String_Type
(Etyp
));
593 if not Is_OK_Static_Choice
(Choice
) then
594 Set_Raises_Constraint_Error
(Choice
);
597 -- Discrete type case
599 elsif Is_Discrete_Type
(Etype
(Expr
)) then
600 Val
:= Expr_Value
(Expr
);
602 if Nkind
(Choice
) = N_Range
then
603 if Val
>= Expr_Value
(Low_Bound
(Choice
))
605 Val
<= Expr_Value
(High_Bound
(Choice
))
612 elsif Nkind
(Choice
) = N_Subtype_Indication
614 (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
616 if Val
>= Expr_Value
(Type_Low_Bound
(Etype
(Choice
)))
618 Val
<= Expr_Value
(Type_High_Bound
(Etype
(Choice
)))
625 elsif Nkind
(Choice
) = N_Others_Choice
then
629 if Val
= Expr_Value
(Choice
) then
638 elsif Is_Real_Type
(Etype
(Expr
)) then
639 ValR
:= Expr_Value_R
(Expr
);
641 if Nkind
(Choice
) = N_Range
then
642 if ValR
>= Expr_Value_R
(Low_Bound
(Choice
))
644 ValR
<= Expr_Value_R
(High_Bound
(Choice
))
651 elsif Nkind
(Choice
) = N_Subtype_Indication
653 (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
655 if ValR
>= Expr_Value_R
(Type_Low_Bound
(Etype
(Choice
)))
657 ValR
<= Expr_Value_R
(Type_High_Bound
(Etype
(Choice
)))
665 if ValR
= Expr_Value_R
(Choice
) then
675 pragma Assert
(Is_String_Type
(Etype
(Expr
)));
676 ValS
:= Expr_Value_S
(Expr
);
678 if Nkind
(Choice
) = N_Subtype_Indication
680 (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
682 if not Is_Constrained
(Etype
(Choice
)) then
687 Typlen
: constant Uint
:=
688 String_Type_Len
(Etype
(Choice
));
689 Strlen
: constant Uint
:=
690 UI_From_Int
(String_Length
(Strval
(ValS
)));
692 if Typlen
= Strlen
then
701 if String_Equal
(Strval
(ValS
), Strval
(Expr_Value_S
(Choice
)))
715 function Choices_Match
717 Choices
: List_Id
) return Match_Result
720 Result
: Match_Result
;
723 Choice
:= First
(Choices
);
724 while Present
(Choice
) loop
725 Result
:= Choice_Matches
(Expr
, Choice
);
727 if Result
/= No_Match
then
737 --------------------------
738 -- Compile_Time_Compare --
739 --------------------------
741 function Compile_Time_Compare
743 Assume_Valid
: Boolean) return Compare_Result
745 Discard
: aliased Uint
;
747 return Compile_Time_Compare
(L
, R
, Discard
'Access, Assume_Valid
);
748 end Compile_Time_Compare
;
750 function Compile_Time_Compare
753 Assume_Valid
: Boolean;
754 Rec
: Boolean := False) return Compare_Result
756 Ltyp
: Entity_Id
:= Underlying_Type
(Etype
(L
));
757 Rtyp
: Entity_Id
:= Underlying_Type
(Etype
(R
));
758 -- These get reset to the base type for the case of entities where
759 -- Is_Known_Valid is not set. This takes care of handling possible
760 -- invalid representations using the value of the base type, in
761 -- accordance with RM 13.9.1(10).
763 Discard
: aliased Uint
;
765 procedure Compare_Decompose
769 -- This procedure decomposes the node N into an expression node and a
770 -- signed offset, so that the value of N is equal to the value of R plus
771 -- the value V (which may be negative). If no such decomposition is
772 -- possible, then on return R is a copy of N, and V is set to zero.
774 function Compare_Fixup
(N
: Node_Id
) return Node_Id
;
775 -- This function deals with replacing 'Last and 'First references with
776 -- their corresponding type bounds, which we then can compare. The
777 -- argument is the original node, the result is the identity, unless we
778 -- have a 'Last/'First reference in which case the value returned is the
779 -- appropriate type bound.
781 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean;
782 -- Even if the context does not assume that values are valid, some
783 -- simple cases can be recognized.
785 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean;
786 -- Returns True iff L and R represent expressions that definitely have
787 -- identical (but not necessarily compile time known) values Indeed the
788 -- caller is expected to have already dealt with the cases of compile
789 -- time known values, so these are not tested here.
791 -----------------------
792 -- Compare_Decompose --
793 -----------------------
795 procedure Compare_Decompose
801 if Nkind
(N
) = N_Op_Add
802 and then Nkind
(Right_Opnd
(N
)) = N_Integer_Literal
805 V
:= Intval
(Right_Opnd
(N
));
808 elsif Nkind
(N
) = N_Op_Subtract
809 and then Nkind
(Right_Opnd
(N
)) = N_Integer_Literal
812 V
:= UI_Negate
(Intval
(Right_Opnd
(N
)));
815 elsif Nkind
(N
) = N_Attribute_Reference
then
816 if Attribute_Name
(N
) = Name_Succ
then
817 R
:= First
(Expressions
(N
));
821 elsif Attribute_Name
(N
) = Name_Pred
then
822 R
:= First
(Expressions
(N
));
830 end Compare_Decompose
;
836 function Compare_Fixup
(N
: Node_Id
) return Node_Id
is
842 -- Fixup only required for First/Last attribute reference
844 if Nkind
(N
) = N_Attribute_Reference
845 and then Nam_In
(Attribute_Name
(N
), Name_First
, Name_Last
)
847 Xtyp
:= Etype
(Prefix
(N
));
849 -- If we have no type, then just abandon the attempt to do
850 -- a fixup, this is probably the result of some other error.
856 -- Dereference an access type
858 if Is_Access_Type
(Xtyp
) then
859 Xtyp
:= Designated_Type
(Xtyp
);
862 -- If we don't have an array type at this stage, something is
863 -- peculiar, e.g. another error, and we abandon the attempt at
866 if not Is_Array_Type
(Xtyp
) then
870 -- Ignore unconstrained array, since bounds are not meaningful
872 if not Is_Constrained
(Xtyp
) then
876 if Ekind
(Xtyp
) = E_String_Literal_Subtype
then
877 if Attribute_Name
(N
) = Name_First
then
878 return String_Literal_Low_Bound
(Xtyp
);
881 Make_Integer_Literal
(Sloc
(N
),
882 Intval
=> Intval
(String_Literal_Low_Bound
(Xtyp
)) +
883 String_Literal_Length
(Xtyp
));
887 -- Find correct index type
889 Indx
:= First_Index
(Xtyp
);
891 if Present
(Expressions
(N
)) then
892 Subs
:= UI_To_Int
(Expr_Value
(First
(Expressions
(N
))));
894 for J
in 2 .. Subs
loop
895 Indx
:= Next_Index
(Indx
);
899 Xtyp
:= Etype
(Indx
);
901 if Attribute_Name
(N
) = Name_First
then
902 return Type_Low_Bound
(Xtyp
);
904 return Type_High_Bound
(Xtyp
);
911 ----------------------------
912 -- Is_Known_Valid_Operand --
913 ----------------------------
915 function Is_Known_Valid_Operand
(Opnd
: Node_Id
) return Boolean is
917 return (Is_Entity_Name
(Opnd
)
919 (Is_Known_Valid
(Entity
(Opnd
))
920 or else Ekind
(Entity
(Opnd
)) = E_In_Parameter
922 (Ekind
(Entity
(Opnd
)) in Object_Kind
923 and then Present
(Current_Value
(Entity
(Opnd
))))))
924 or else Is_OK_Static_Expression
(Opnd
);
925 end Is_Known_Valid_Operand
;
931 function Is_Same_Value
(L
, R
: Node_Id
) return Boolean is
932 Lf
: constant Node_Id
:= Compare_Fixup
(L
);
933 Rf
: constant Node_Id
:= Compare_Fixup
(R
);
935 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean;
936 -- L, R are the Expressions values from two attribute nodes for First
937 -- or Last attributes. Either may be set to No_List if no expressions
938 -- are present (indicating subscript 1). The result is True if both
939 -- expressions represent the same subscript (note one case is where
940 -- one subscript is missing and the other is explicitly set to 1).
942 -----------------------
943 -- Is_Same_Subscript --
944 -----------------------
946 function Is_Same_Subscript
(L
, R
: List_Id
) return Boolean is
952 return Expr_Value
(First
(R
)) = Uint_1
;
957 return Expr_Value
(First
(L
)) = Uint_1
;
959 return Expr_Value
(First
(L
)) = Expr_Value
(First
(R
));
962 end Is_Same_Subscript
;
964 -- Start of processing for Is_Same_Value
967 -- Values are the same if they refer to the same entity and the
968 -- entity is non-volatile. This does not however apply to Float
969 -- types, since we may have two NaN values and they should never
972 -- If the entity is a discriminant, the two expressions may be bounds
973 -- of components of objects of the same discriminated type. The
974 -- values of the discriminants are not static, and therefore the
975 -- result is unknown.
977 -- It would be better to comment individual branches of this test ???
979 if Nkind_In
(Lf
, N_Identifier
, N_Expanded_Name
)
980 and then Nkind_In
(Rf
, N_Identifier
, N_Expanded_Name
)
981 and then Entity
(Lf
) = Entity
(Rf
)
982 and then Ekind
(Entity
(Lf
)) /= E_Discriminant
983 and then Present
(Entity
(Lf
))
984 and then not Is_Floating_Point_Type
(Etype
(L
))
985 and then not Is_Volatile_Reference
(L
)
986 and then not Is_Volatile_Reference
(R
)
990 -- Or if they are compile time known and identical
992 elsif Compile_Time_Known_Value
(Lf
)
994 Compile_Time_Known_Value
(Rf
)
995 and then Expr_Value
(Lf
) = Expr_Value
(Rf
)
999 -- False if Nkind of the two nodes is different for remaining cases
1001 elsif Nkind
(Lf
) /= Nkind
(Rf
) then
1004 -- True if both 'First or 'Last values applying to the same entity
1005 -- (first and last don't change even if value does). Note that we
1006 -- need this even with the calls to Compare_Fixup, to handle the
1007 -- case of unconstrained array attributes where Compare_Fixup
1008 -- cannot find useful bounds.
1010 elsif Nkind
(Lf
) = N_Attribute_Reference
1011 and then Attribute_Name
(Lf
) = Attribute_Name
(Rf
)
1012 and then Nam_In
(Attribute_Name
(Lf
), Name_First
, Name_Last
)
1013 and then Nkind_In
(Prefix
(Lf
), N_Identifier
, N_Expanded_Name
)
1014 and then Nkind_In
(Prefix
(Rf
), N_Identifier
, N_Expanded_Name
)
1015 and then Entity
(Prefix
(Lf
)) = Entity
(Prefix
(Rf
))
1016 and then Is_Same_Subscript
(Expressions
(Lf
), Expressions
(Rf
))
1020 -- True if the same selected component from the same record
1022 elsif Nkind
(Lf
) = N_Selected_Component
1023 and then Selector_Name
(Lf
) = Selector_Name
(Rf
)
1024 and then Is_Same_Value
(Prefix
(Lf
), Prefix
(Rf
))
1028 -- True if the same unary operator applied to the same operand
1030 elsif Nkind
(Lf
) in N_Unary_Op
1031 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
1035 -- True if the same binary operator applied to the same operands
1037 elsif Nkind
(Lf
) in N_Binary_Op
1038 and then Is_Same_Value
(Left_Opnd
(Lf
), Left_Opnd
(Rf
))
1039 and then Is_Same_Value
(Right_Opnd
(Lf
), Right_Opnd
(Rf
))
1043 -- All other cases, we can't tell, so return False
1050 -- Start of processing for Compile_Time_Compare
1053 Diff
.all := No_Uint
;
1055 -- In preanalysis mode, always return Unknown unless the expression
1056 -- is static. It is too early to be thinking we know the result of a
1057 -- comparison, save that judgment for the full analysis. This is
1058 -- particularly important in the case of pre and postconditions, which
1059 -- otherwise can be prematurely collapsed into having True or False
1060 -- conditions when this is inappropriate.
1062 if not (Full_Analysis
1063 or else (Is_OK_Static_Expression
(L
)
1065 Is_OK_Static_Expression
(R
)))
1070 -- If either operand could raise constraint error, then we cannot
1071 -- know the result at compile time (since CE may be raised).
1073 if not (Cannot_Raise_Constraint_Error
(L
)
1075 Cannot_Raise_Constraint_Error
(R
))
1080 -- Identical operands are most certainly equal
1085 -- If expressions have no types, then do not attempt to determine if
1086 -- they are the same, since something funny is going on. One case in
1087 -- which this happens is during generic template analysis, when bounds
1088 -- are not fully analyzed.
1090 elsif No
(Ltyp
) or else No
(Rtyp
) then
1093 -- We do not attempt comparisons for packed arrays arrays represented as
1094 -- modular types, where the semantics of comparison is quite different.
1096 elsif Is_Packed_Array_Impl_Type
(Ltyp
)
1097 and then Is_Modular_Integer_Type
(Ltyp
)
1101 -- For access types, the only time we know the result at compile time
1102 -- (apart from identical operands, which we handled already) is if we
1103 -- know one operand is null and the other is not, or both operands are
1106 elsif Is_Access_Type
(Ltyp
) then
1107 if Known_Null
(L
) then
1108 if Known_Null
(R
) then
1110 elsif Known_Non_Null
(R
) then
1116 elsif Known_Non_Null
(L
) and then Known_Null
(R
) then
1123 -- Case where comparison involves two compile time known values
1125 elsif Compile_Time_Known_Value
(L
)
1127 Compile_Time_Known_Value
(R
)
1129 -- For the floating-point case, we have to be a little careful, since
1130 -- at compile time we are dealing with universal exact values, but at
1131 -- runtime, these will be in non-exact target form. That's why the
1132 -- returned results are LE and GE below instead of LT and GT.
1134 if Is_Floating_Point_Type
(Ltyp
)
1136 Is_Floating_Point_Type
(Rtyp
)
1139 Lo
: constant Ureal
:= Expr_Value_R
(L
);
1140 Hi
: constant Ureal
:= Expr_Value_R
(R
);
1151 -- For string types, we have two string literals and we proceed to
1152 -- compare them using the Ada style dictionary string comparison.
1154 elsif not Is_Scalar_Type
(Ltyp
) then
1156 Lstring
: constant String_Id
:= Strval
(Expr_Value_S
(L
));
1157 Rstring
: constant String_Id
:= Strval
(Expr_Value_S
(R
));
1158 Llen
: constant Nat
:= String_Length
(Lstring
);
1159 Rlen
: constant Nat
:= String_Length
(Rstring
);
1162 for J
in 1 .. Nat
'Min (Llen
, Rlen
) loop
1164 LC
: constant Char_Code
:= Get_String_Char
(Lstring
, J
);
1165 RC
: constant Char_Code
:= Get_String_Char
(Rstring
, J
);
1177 elsif Llen
> Rlen
then
1184 -- For remaining scalar cases we know exactly (note that this does
1185 -- include the fixed-point case, where we know the run time integer
1190 Lo
: constant Uint
:= Expr_Value
(L
);
1191 Hi
: constant Uint
:= Expr_Value
(R
);
1194 Diff
.all := Hi
- Lo
;
1199 Diff
.all := Lo
- Hi
;
1205 -- Cases where at least one operand is not known at compile time
1208 -- Remaining checks apply only for discrete types
1210 if not Is_Discrete_Type
(Ltyp
)
1212 not Is_Discrete_Type
(Rtyp
)
1217 -- Defend against generic types, or actually any expressions that
1218 -- contain a reference to a generic type from within a generic
1219 -- template. We don't want to do any range analysis of such
1220 -- expressions for two reasons. First, the bounds of a generic type
1221 -- itself are junk and cannot be used for any kind of analysis.
1222 -- Second, we may have a case where the range at run time is indeed
1223 -- known, but we don't want to do compile time analysis in the
1224 -- template based on that range since in an instance the value may be
1225 -- static, and able to be elaborated without reference to the bounds
1226 -- of types involved. As an example, consider:
1228 -- (F'Pos (F'Last) + 1) > Integer'Last
1230 -- The expression on the left side of > is Universal_Integer and thus
1231 -- acquires the type Integer for evaluation at run time, and at run
1232 -- time it is true that this condition is always False, but within
1233 -- an instance F may be a type with a static range greater than the
1234 -- range of Integer, and the expression statically evaluates to True.
1236 if References_Generic_Formal_Type
(L
)
1238 References_Generic_Formal_Type
(R
)
1243 -- Replace types by base types for the case of values which are not
1244 -- known to have valid representations. This takes care of properly
1245 -- dealing with invalid representations.
1247 if not Assume_Valid
then
1248 if not (Is_Entity_Name
(L
)
1249 and then (Is_Known_Valid
(Entity
(L
))
1250 or else Assume_No_Invalid_Values
))
1252 Ltyp
:= Underlying_Type
(Base_Type
(Ltyp
));
1255 if not (Is_Entity_Name
(R
)
1256 and then (Is_Known_Valid
(Entity
(R
))
1257 or else Assume_No_Invalid_Values
))
1259 Rtyp
:= Underlying_Type
(Base_Type
(Rtyp
));
1263 -- First attempt is to decompose the expressions to extract a
1264 -- constant offset resulting from the use of any of the forms:
1271 -- Then we see if the two expressions are the same value, and if so
1272 -- the result is obtained by comparing the offsets.
1274 -- Note: the reason we do this test first is that it returns only
1275 -- decisive results (with diff set), where other tests, like the
1276 -- range test, may not be as so decisive. Consider for example
1277 -- J .. J + 1. This code can conclude LT with a difference of 1,
1278 -- even if the range of J is not known.
1287 Compare_Decompose
(L
, Lnode
, Loffs
);
1288 Compare_Decompose
(R
, Rnode
, Roffs
);
1290 if Is_Same_Value
(Lnode
, Rnode
) then
1291 if Loffs
= Roffs
then
1293 elsif Loffs
< Roffs
then
1294 Diff
.all := Roffs
- Loffs
;
1297 Diff
.all := Loffs
- Roffs
;
1303 -- Next, try range analysis and see if operand ranges are disjoint
1311 -- True if each range is a single point
1314 Determine_Range
(L
, LOK
, LLo
, LHi
, Assume_Valid
);
1315 Determine_Range
(R
, ROK
, RLo
, RHi
, Assume_Valid
);
1318 Single
:= (LLo
= LHi
) and then (RLo
= RHi
);
1321 if Single
and Assume_Valid
then
1322 Diff
.all := RLo
- LLo
;
1327 elsif RHi
< LLo
then
1328 if Single
and Assume_Valid
then
1329 Diff
.all := LLo
- RLo
;
1334 elsif Single
and then LLo
= RLo
then
1336 -- If the range includes a single literal and we can assume
1337 -- validity then the result is known even if an operand is
1340 if Assume_Valid
then
1346 elsif LHi
= RLo
then
1349 elsif RHi
= LLo
then
1352 elsif not Is_Known_Valid_Operand
(L
)
1353 and then not Assume_Valid
1355 if Is_Same_Value
(L
, R
) then
1362 -- If the range of either operand cannot be determined, nothing
1363 -- further can be inferred.
1370 -- Here is where we check for comparisons against maximum bounds of
1371 -- types, where we know that no value can be outside the bounds of
1372 -- the subtype. Note that this routine is allowed to assume that all
1373 -- expressions are within their subtype bounds. Callers wishing to
1374 -- deal with possibly invalid values must in any case take special
1375 -- steps (e.g. conversions to larger types) to avoid this kind of
1376 -- optimization, which is always considered to be valid. We do not
1377 -- attempt this optimization with generic types, since the type
1378 -- bounds may not be meaningful in this case.
1380 -- We are in danger of an infinite recursion here. It does not seem
1381 -- useful to go more than one level deep, so the parameter Rec is
1382 -- used to protect ourselves against this infinite recursion.
1386 -- See if we can get a decisive check against one operand and a
1387 -- bound of the other operand (four possible tests here). Note
1388 -- that we avoid testing junk bounds of a generic type.
1390 if not Is_Generic_Type
(Rtyp
) then
1391 case Compile_Time_Compare
(L
, Type_Low_Bound
(Rtyp
),
1393 Assume_Valid
, Rec
=> True)
1395 when LT
=> return LT
;
1396 when LE
=> return LE
;
1397 when EQ
=> return LE
;
1398 when others => null;
1401 case Compile_Time_Compare
(L
, Type_High_Bound
(Rtyp
),
1403 Assume_Valid
, Rec
=> True)
1405 when GT
=> return GT
;
1406 when GE
=> return GE
;
1407 when EQ
=> return GE
;
1408 when others => null;
1412 if not Is_Generic_Type
(Ltyp
) then
1413 case Compile_Time_Compare
(Type_Low_Bound
(Ltyp
), R
,
1415 Assume_Valid
, Rec
=> True)
1417 when GT
=> return GT
;
1418 when GE
=> return GE
;
1419 when EQ
=> return GE
;
1420 when others => null;
1423 case Compile_Time_Compare
(Type_High_Bound
(Ltyp
), R
,
1425 Assume_Valid
, Rec
=> True)
1427 when LT
=> return LT
;
1428 when LE
=> return LE
;
1429 when EQ
=> return LE
;
1430 when others => null;
1435 -- Next attempt is to see if we have an entity compared with a
1436 -- compile time known value, where there is a current value
1437 -- conditional for the entity which can tell us the result.
1441 -- Entity variable (left operand)
1444 -- Value (right operand)
1447 -- If False, we have reversed the operands
1450 -- Comparison operator kind from Get_Current_Value_Condition call
1453 -- Value from Get_Current_Value_Condition call
1458 Result
: Compare_Result
;
1459 -- Known result before inversion
1462 if Is_Entity_Name
(L
)
1463 and then Compile_Time_Known_Value
(R
)
1466 Val
:= Expr_Value
(R
);
1469 elsif Is_Entity_Name
(R
)
1470 and then Compile_Time_Known_Value
(L
)
1473 Val
:= Expr_Value
(L
);
1476 -- That was the last chance at finding a compile time result
1482 Get_Current_Value_Condition
(Var
, Op
, Opn
);
1484 -- That was the last chance, so if we got nothing return
1490 Opv
:= Expr_Value
(Opn
);
1492 -- We got a comparison, so we might have something interesting
1494 -- Convert LE to LT and GE to GT, just so we have fewer cases
1496 if Op
= N_Op_Le
then
1500 elsif Op
= N_Op_Ge
then
1505 -- Deal with equality case
1507 if Op
= N_Op_Eq
then
1510 elsif Opv
< Val
then
1516 -- Deal with inequality case
1518 elsif Op
= N_Op_Ne
then
1525 -- Deal with greater than case
1527 elsif Op
= N_Op_Gt
then
1530 elsif Opv
= Val
- 1 then
1536 -- Deal with less than case
1538 else pragma Assert
(Op
= N_Op_Lt
);
1541 elsif Opv
= Val
+ 1 then
1548 -- Deal with inverting result
1552 when GT
=> return LT
;
1553 when GE
=> return LE
;
1554 when LT
=> return GT
;
1555 when LE
=> return GE
;
1556 when others => return Result
;
1563 end Compile_Time_Compare
;
1565 -------------------------------
1566 -- Compile_Time_Known_Bounds --
1567 -------------------------------
1569 function Compile_Time_Known_Bounds
(T
: Entity_Id
) return Boolean is
1574 if T
= Any_Composite
or else not Is_Array_Type
(T
) then
1578 Indx
:= First_Index
(T
);
1579 while Present
(Indx
) loop
1580 Typ
:= Underlying_Type
(Etype
(Indx
));
1582 -- Never look at junk bounds of a generic type
1584 if Is_Generic_Type
(Typ
) then
1588 -- Otherwise check bounds for compile time known
1590 if not Compile_Time_Known_Value
(Type_Low_Bound
(Typ
)) then
1592 elsif not Compile_Time_Known_Value
(Type_High_Bound
(Typ
)) then
1600 end Compile_Time_Known_Bounds
;
1602 ------------------------------
1603 -- Compile_Time_Known_Value --
1604 ------------------------------
1606 function Compile_Time_Known_Value
(Op
: Node_Id
) return Boolean is
1607 K
: constant Node_Kind
:= Nkind
(Op
);
1608 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(Op
) mod CV_Cache_Size
);
1611 -- Never known at compile time if bad type or raises constraint error
1612 -- or empty (latter case occurs only as a result of a previous error).
1615 Check_Error_Detected
;
1619 or else Etype
(Op
) = Any_Type
1620 or else Raises_Constraint_Error
(Op
)
1625 -- If we have an entity name, then see if it is the name of a constant
1626 -- and if so, test the corresponding constant value, or the name of
1627 -- an enumeration literal, which is always a constant.
1629 if Present
(Etype
(Op
)) and then Is_Entity_Name
(Op
) then
1631 E
: constant Entity_Id
:= Entity
(Op
);
1635 -- Never known at compile time if it is a packed array value.
1636 -- We might want to try to evaluate these at compile time one
1637 -- day, but we do not make that attempt now.
1639 if Is_Packed_Array_Impl_Type
(Etype
(Op
)) then
1643 if Ekind
(E
) = E_Enumeration_Literal
then
1646 elsif Ekind
(E
) = E_Constant
then
1647 V
:= Constant_Value
(E
);
1648 return Present
(V
) and then Compile_Time_Known_Value
(V
);
1652 -- We have a value, see if it is compile time known
1655 -- Integer literals are worth storing in the cache
1657 if K
= N_Integer_Literal
then
1659 CV_Ent
.V
:= Intval
(Op
);
1662 -- Other literals and NULL are known at compile time
1665 Nkind_In
(K
, N_Character_Literal
,
1674 -- If we fall through, not known at compile time
1678 -- If we get an exception while trying to do this test, then some error
1679 -- has occurred, and we simply say that the value is not known after all
1684 end Compile_Time_Known_Value
;
1686 --------------------------------------
1687 -- Compile_Time_Known_Value_Or_Aggr --
1688 --------------------------------------
1690 function Compile_Time_Known_Value_Or_Aggr
(Op
: Node_Id
) return Boolean is
1692 -- If we have an entity name, then see if it is the name of a constant
1693 -- and if so, test the corresponding constant value, or the name of
1694 -- an enumeration literal, which is always a constant.
1696 if Is_Entity_Name
(Op
) then
1698 E
: constant Entity_Id
:= Entity
(Op
);
1702 if Ekind
(E
) = E_Enumeration_Literal
then
1705 elsif Ekind
(E
) /= E_Constant
then
1709 V
:= Constant_Value
(E
);
1711 and then Compile_Time_Known_Value_Or_Aggr
(V
);
1715 -- We have a value, see if it is compile time known
1718 if Compile_Time_Known_Value
(Op
) then
1721 elsif Nkind
(Op
) = N_Aggregate
then
1723 if Present
(Expressions
(Op
)) then
1727 Expr
:= First
(Expressions
(Op
));
1728 while Present
(Expr
) loop
1729 if not Compile_Time_Known_Value_Or_Aggr
(Expr
) then
1738 if Present
(Component_Associations
(Op
)) then
1743 Cass
:= First
(Component_Associations
(Op
));
1744 while Present
(Cass
) loop
1746 Compile_Time_Known_Value_Or_Aggr
(Expression
(Cass
))
1758 -- All other types of values are not known at compile time
1765 end Compile_Time_Known_Value_Or_Aggr
;
1767 ---------------------------------------
1768 -- CRT_Safe_Compile_Time_Known_Value --
1769 ---------------------------------------
1771 function CRT_Safe_Compile_Time_Known_Value
(Op
: Node_Id
) return Boolean is
1773 if (Configurable_Run_Time_Mode
or No_Run_Time_Mode
)
1774 and then not Is_OK_Static_Expression
(Op
)
1778 return Compile_Time_Known_Value
(Op
);
1780 end CRT_Safe_Compile_Time_Known_Value
;
1786 -- This is only called for actuals of functions that are not predefined
1787 -- operators (which have already been rewritten as operators at this
1788 -- stage), so the call can never be folded, and all that needs doing for
1789 -- the actual is to do the check for a non-static context.
1791 procedure Eval_Actual
(N
: Node_Id
) is
1793 Check_Non_Static_Context
(N
);
1796 --------------------
1797 -- Eval_Allocator --
1798 --------------------
1800 -- Allocators are never static, so all we have to do is to do the
1801 -- check for a non-static context if an expression is present.
1803 procedure Eval_Allocator
(N
: Node_Id
) is
1804 Expr
: constant Node_Id
:= Expression
(N
);
1806 if Nkind
(Expr
) = N_Qualified_Expression
then
1807 Check_Non_Static_Context
(Expression
(Expr
));
1811 ------------------------
1812 -- Eval_Arithmetic_Op --
1813 ------------------------
1815 -- Arithmetic operations are static functions, so the result is static
1816 -- if both operands are static (RM 4.9(7), 4.9(20)).
1818 procedure Eval_Arithmetic_Op
(N
: Node_Id
) is
1819 Left
: constant Node_Id
:= Left_Opnd
(N
);
1820 Right
: constant Node_Id
:= Right_Opnd
(N
);
1821 Ltype
: constant Entity_Id
:= Etype
(Left
);
1822 Rtype
: constant Entity_Id
:= Etype
(Right
);
1823 Otype
: Entity_Id
:= Empty
;
1828 -- If not foldable we are done
1830 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
1836 -- Otherwise attempt to fold
1838 if Is_Universal_Numeric_Type
(Etype
(Left
))
1840 Is_Universal_Numeric_Type
(Etype
(Right
))
1842 Otype
:= Find_Universal_Operator_Type
(N
);
1845 -- Fold for cases where both operands are of integer type
1847 if Is_Integer_Type
(Ltype
) and then Is_Integer_Type
(Rtype
) then
1849 Left_Int
: constant Uint
:= Expr_Value
(Left
);
1850 Right_Int
: constant Uint
:= Expr_Value
(Right
);
1856 Result
:= Left_Int
+ Right_Int
;
1858 when N_Op_Subtract
=>
1859 Result
:= Left_Int
- Right_Int
;
1861 when N_Op_Multiply
=>
1864 (Num_Bits
(Left_Int
) + Num_Bits
(Right_Int
)))
1866 Result
:= Left_Int
* Right_Int
;
1873 -- The exception Constraint_Error is raised by integer
1874 -- division, rem and mod if the right operand is zero.
1876 if Right_Int
= 0 then
1877 Apply_Compile_Time_Constraint_Error
1878 (N
, "division by zero", CE_Divide_By_Zero
,
1880 Set_Raises_Constraint_Error
(N
);
1883 -- Otherwise we can do the division
1886 Result
:= Left_Int
/ Right_Int
;
1891 -- The exception Constraint_Error is raised by integer
1892 -- division, rem and mod if the right operand is zero.
1894 if Right_Int
= 0 then
1895 Apply_Compile_Time_Constraint_Error
1896 (N
, "mod with zero divisor", CE_Divide_By_Zero
,
1900 Result
:= Left_Int
mod Right_Int
;
1905 -- The exception Constraint_Error is raised by integer
1906 -- division, rem and mod if the right operand is zero.
1908 if Right_Int
= 0 then
1909 Apply_Compile_Time_Constraint_Error
1910 (N
, "rem with zero divisor", CE_Divide_By_Zero
,
1915 Result
:= Left_Int
rem Right_Int
;
1919 raise Program_Error
;
1922 -- Adjust the result by the modulus if the type is a modular type
1924 if Is_Modular_Integer_Type
(Ltype
) then
1925 Result
:= Result
mod Modulus
(Ltype
);
1927 -- For a signed integer type, check non-static overflow
1929 elsif (not Stat
) and then Is_Signed_Integer_Type
(Ltype
) then
1931 BT
: constant Entity_Id
:= Base_Type
(Ltype
);
1932 Lo
: constant Uint
:= Expr_Value
(Type_Low_Bound
(BT
));
1933 Hi
: constant Uint
:= Expr_Value
(Type_High_Bound
(BT
));
1935 if Result
< Lo
or else Result
> Hi
then
1936 Apply_Compile_Time_Constraint_Error
1937 (N
, "value not in range of }??",
1938 CE_Overflow_Check_Failed
,
1945 -- If we get here we can fold the result
1947 Fold_Uint
(N
, Result
, Stat
);
1950 -- Cases where at least one operand is a real. We handle the cases of
1951 -- both reals, or mixed/real integer cases (the latter happen only for
1952 -- divide and multiply, and the result is always real).
1954 elsif Is_Real_Type
(Ltype
) or else Is_Real_Type
(Rtype
) then
1961 if Is_Real_Type
(Ltype
) then
1962 Left_Real
:= Expr_Value_R
(Left
);
1964 Left_Real
:= UR_From_Uint
(Expr_Value
(Left
));
1967 if Is_Real_Type
(Rtype
) then
1968 Right_Real
:= Expr_Value_R
(Right
);
1970 Right_Real
:= UR_From_Uint
(Expr_Value
(Right
));
1973 if Nkind
(N
) = N_Op_Add
then
1974 Result
:= Left_Real
+ Right_Real
;
1976 elsif Nkind
(N
) = N_Op_Subtract
then
1977 Result
:= Left_Real
- Right_Real
;
1979 elsif Nkind
(N
) = N_Op_Multiply
then
1980 Result
:= Left_Real
* Right_Real
;
1982 else pragma Assert
(Nkind
(N
) = N_Op_Divide
);
1983 if UR_Is_Zero
(Right_Real
) then
1984 Apply_Compile_Time_Constraint_Error
1985 (N
, "division by zero", CE_Divide_By_Zero
);
1989 Result
:= Left_Real
/ Right_Real
;
1992 Fold_Ureal
(N
, Result
, Stat
);
1996 -- If the operator was resolved to a specific type, make sure that type
1997 -- is frozen even if the expression is folded into a literal (which has
1998 -- a universal type).
2000 if Present
(Otype
) then
2001 Freeze_Before
(N
, Otype
);
2003 end Eval_Arithmetic_Op
;
2005 ----------------------------
2006 -- Eval_Character_Literal --
2007 ----------------------------
2009 -- Nothing to be done
2011 procedure Eval_Character_Literal
(N
: Node_Id
) is
2012 pragma Warnings
(Off
, N
);
2015 end Eval_Character_Literal
;
2021 -- Static function calls are either calls to predefined operators
2022 -- with static arguments, or calls to functions that rename a literal.
2023 -- Only the latter case is handled here, predefined operators are
2024 -- constant-folded elsewhere.
2026 -- If the function is itself inherited (see 7423-001) the literal of
2027 -- the parent type must be explicitly converted to the return type
2030 procedure Eval_Call
(N
: Node_Id
) is
2031 Loc
: constant Source_Ptr
:= Sloc
(N
);
2032 Typ
: constant Entity_Id
:= Etype
(N
);
2036 if Nkind
(N
) = N_Function_Call
2037 and then No
(Parameter_Associations
(N
))
2038 and then Is_Entity_Name
(Name
(N
))
2039 and then Present
(Alias
(Entity
(Name
(N
))))
2040 and then Is_Enumeration_Type
(Base_Type
(Typ
))
2042 Lit
:= Ultimate_Alias
(Entity
(Name
(N
)));
2044 if Ekind
(Lit
) = E_Enumeration_Literal
then
2045 if Base_Type
(Etype
(Lit
)) /= Base_Type
(Typ
) then
2047 (N
, Convert_To
(Typ
, New_Occurrence_Of
(Lit
, Loc
)));
2049 Rewrite
(N
, New_Occurrence_Of
(Lit
, Loc
));
2057 --------------------------
2058 -- Eval_Case_Expression --
2059 --------------------------
2061 -- A conditional expression is static if all its conditions and dependent
2062 -- expressions are static. Note that we do not care if the dependent
2063 -- expressions raise CE, except for the one that will be selected.
2065 procedure Eval_Case_Expression
(N
: Node_Id
) is
2070 Set_Is_Static_Expression
(N
, False);
2072 if not Is_Static_Expression
(Expression
(N
)) then
2073 Check_Non_Static_Context
(Expression
(N
));
2077 -- First loop, make sure all the alternatives are static expressions
2078 -- none of which raise Constraint_Error. We make the constraint error
2079 -- check because part of the legality condition for a correct static
2080 -- case expression is that the cases are covered, like any other case
2081 -- expression. And we can't do that if any of the conditions raise an
2082 -- exception, so we don't even try to evaluate if that is the case.
2084 Alt
:= First
(Alternatives
(N
));
2085 while Present
(Alt
) loop
2087 -- The expression must be static, but we don't care at this stage
2088 -- if it raises Constraint_Error (the alternative might not match,
2089 -- in which case the expression is statically unevaluated anyway).
2091 if not Is_Static_Expression
(Expression
(Alt
)) then
2092 Check_Non_Static_Context
(Expression
(Alt
));
2096 -- The choices of a case always have to be static, and cannot raise
2097 -- an exception. If this condition is not met, then the expression
2098 -- is plain illegal, so just abandon evaluation attempts. No need
2099 -- to check non-static context when we have something illegal anyway.
2101 if not Is_OK_Static_Choice_List
(Discrete_Choices
(Alt
)) then
2108 -- OK, if the above loop gets through it means that all choices are OK
2109 -- static (don't raise exceptions), so the whole case is static, and we
2110 -- can find the matching alternative.
2112 Set_Is_Static_Expression
(N
);
2114 -- Now to deal with propagating a possible constraint error
2116 -- If the selecting expression raises CE, propagate and we are done
2118 if Raises_Constraint_Error
(Expression
(N
)) then
2119 Set_Raises_Constraint_Error
(N
);
2121 -- Otherwise we need to check the alternatives to find the matching
2122 -- one. CE's in other than the matching one are not relevant. But we
2123 -- do need to check the matching one. Unlike the first loop, we do not
2124 -- have to go all the way through, when we find the matching one, quit.
2127 Alt
:= First
(Alternatives
(N
));
2130 -- We must find a match among the alternatives. If not, this must
2131 -- be due to other errors, so just ignore, leaving as non-static.
2134 Set_Is_Static_Expression
(N
, False);
2138 -- Otherwise loop through choices of this alternative
2140 Choice
:= First
(Discrete_Choices
(Alt
));
2141 while Present
(Choice
) loop
2143 -- If we find a matching choice, then the Expression of this
2144 -- alternative replaces N (Raises_Constraint_Error flag is
2145 -- included, so we don't have to special case that).
2147 if Choice_Matches
(Expression
(N
), Choice
) = Match
then
2148 Rewrite
(N
, Relocate_Node
(Expression
(Alt
)));
2158 end Eval_Case_Expression
;
2160 ------------------------
2161 -- Eval_Concatenation --
2162 ------------------------
2164 -- Concatenation is a static function, so the result is static if both
2165 -- operands are static (RM 4.9(7), 4.9(21)).
2167 procedure Eval_Concatenation
(N
: Node_Id
) is
2168 Left
: constant Node_Id
:= Left_Opnd
(N
);
2169 Right
: constant Node_Id
:= Right_Opnd
(N
);
2170 C_Typ
: constant Entity_Id
:= Root_Type
(Component_Type
(Etype
(N
)));
2175 -- Concatenation is never static in Ada 83, so if Ada 83 check operand
2176 -- non-static context.
2178 if Ada_Version
= Ada_83
2179 and then Comes_From_Source
(N
)
2181 Check_Non_Static_Context
(Left
);
2182 Check_Non_Static_Context
(Right
);
2186 -- If not foldable we are done. In principle concatenation that yields
2187 -- any string type is static (i.e. an array type of character types).
2188 -- However, character types can include enumeration literals, and
2189 -- concatenation in that case cannot be described by a literal, so we
2190 -- only consider the operation static if the result is an array of
2191 -- (a descendant of) a predefined character type.
2193 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2195 if not (Is_Standard_Character_Type
(C_Typ
) and then Fold
) then
2196 Set_Is_Static_Expression
(N
, False);
2200 -- Compile time string concatenation
2202 -- ??? Note that operands that are aggregates can be marked as static,
2203 -- so we should attempt at a later stage to fold concatenations with
2207 Left_Str
: constant Node_Id
:= Get_String_Val
(Left
);
2209 Right_Str
: constant Node_Id
:= Get_String_Val
(Right
);
2210 Folded_Val
: String_Id
;
2213 -- Establish new string literal, and store left operand. We make
2214 -- sure to use the special Start_String that takes an operand if
2215 -- the left operand is a string literal. Since this is optimized
2216 -- in the case where that is the most recently created string
2217 -- literal, we ensure efficient time/space behavior for the
2218 -- case of a concatenation of a series of string literals.
2220 if Nkind
(Left_Str
) = N_String_Literal
then
2221 Left_Len
:= String_Length
(Strval
(Left_Str
));
2223 -- If the left operand is the empty string, and the right operand
2224 -- is a string literal (the case of "" & "..."), the result is the
2225 -- value of the right operand. This optimization is important when
2226 -- Is_Folded_In_Parser, to avoid copying an enormous right
2229 if Left_Len
= 0 and then Nkind
(Right_Str
) = N_String_Literal
then
2230 Folded_Val
:= Strval
(Right_Str
);
2232 Start_String
(Strval
(Left_Str
));
2237 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Left_Str
)));
2241 -- Now append the characters of the right operand, unless we
2242 -- optimized the "" & "..." case above.
2244 if Nkind
(Right_Str
) = N_String_Literal
then
2245 if Left_Len
/= 0 then
2246 Store_String_Chars
(Strval
(Right_Str
));
2247 Folded_Val
:= End_String
;
2250 Store_String_Char
(UI_To_CC
(Char_Literal_Value
(Right_Str
)));
2251 Folded_Val
:= End_String
;
2254 Set_Is_Static_Expression
(N
, Stat
);
2256 -- If left operand is the empty string, the result is the
2257 -- right operand, including its bounds if anomalous.
2260 and then Is_Array_Type
(Etype
(Right
))
2261 and then Etype
(Right
) /= Any_String
2263 Set_Etype
(N
, Etype
(Right
));
2266 Fold_Str
(N
, Folded_Val
, Static
=> Stat
);
2268 end Eval_Concatenation
;
2270 ----------------------
2271 -- Eval_Entity_Name --
2272 ----------------------
2274 -- This procedure is used for identifiers and expanded names other than
2275 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
2276 -- static if they denote a static constant (RM 4.9(6)) or if the name
2277 -- denotes an enumeration literal (RM 4.9(22)).
2279 procedure Eval_Entity_Name
(N
: Node_Id
) is
2280 Def_Id
: constant Entity_Id
:= Entity
(N
);
2284 -- Enumeration literals are always considered to be constants
2285 -- and cannot raise constraint error (RM 4.9(22)).
2287 if Ekind
(Def_Id
) = E_Enumeration_Literal
then
2288 Set_Is_Static_Expression
(N
);
2291 -- A name is static if it denotes a static constant (RM 4.9(5)), and
2292 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
2293 -- it does not violate 10.2.1(8) here, since this is not a variable.
2295 elsif Ekind
(Def_Id
) = E_Constant
then
2297 -- Deferred constants must always be treated as nonstatic outside the
2298 -- scope of their full view.
2300 if Present
(Full_View
(Def_Id
))
2301 and then not In_Open_Scopes
(Scope
(Def_Id
))
2305 Val
:= Constant_Value
(Def_Id
);
2308 if Present
(Val
) then
2309 Set_Is_Static_Expression
2310 (N
, Is_Static_Expression
(Val
)
2311 and then Is_Static_Subtype
(Etype
(Def_Id
)));
2312 Set_Raises_Constraint_Error
(N
, Raises_Constraint_Error
(Val
));
2314 if not Is_Static_Expression
(N
)
2315 and then not Is_Generic_Type
(Etype
(N
))
2317 Validate_Static_Object_Name
(N
);
2320 -- Mark constant condition in SCOs
2323 and then Comes_From_Source
(N
)
2324 and then Is_Boolean_Type
(Etype
(Def_Id
))
2325 and then Compile_Time_Known_Value
(N
)
2327 Set_SCO_Condition
(N
, Expr_Value_E
(N
) = Standard_True
);
2334 -- Fall through if the name is not static
2336 Validate_Static_Object_Name
(N
);
2337 end Eval_Entity_Name
;
2339 ------------------------
2340 -- Eval_If_Expression --
2341 ------------------------
2343 -- We can fold to a static expression if the condition and both dependent
2344 -- expressions are static. Otherwise, the only required processing is to do
2345 -- the check for non-static context for the then and else expressions.
2347 procedure Eval_If_Expression
(N
: Node_Id
) is
2348 Condition
: constant Node_Id
:= First
(Expressions
(N
));
2349 Then_Expr
: constant Node_Id
:= Next
(Condition
);
2350 Else_Expr
: constant Node_Id
:= Next
(Then_Expr
);
2352 Non_Result
: Node_Id
;
2354 Rstat
: constant Boolean :=
2355 Is_Static_Expression
(Condition
)
2357 Is_Static_Expression
(Then_Expr
)
2359 Is_Static_Expression
(Else_Expr
);
2360 -- True if result is static
2363 -- If result not static, nothing to do, otherwise set static result
2368 Set_Is_Static_Expression
(N
);
2371 -- If any operand is Any_Type, just propagate to result and do not try
2372 -- to fold, this prevents cascaded errors.
2374 if Etype
(Condition
) = Any_Type
or else
2375 Etype
(Then_Expr
) = Any_Type
or else
2376 Etype
(Else_Expr
) = Any_Type
2378 Set_Etype
(N
, Any_Type
);
2379 Set_Is_Static_Expression
(N
, False);
2383 -- If condition raises constraint error then we have already signaled
2384 -- an error, and we just propagate to the result and do not fold.
2386 if Raises_Constraint_Error
(Condition
) then
2387 Set_Raises_Constraint_Error
(N
);
2391 -- Static case where we can fold. Note that we don't try to fold cases
2392 -- where the condition is known at compile time, but the result is
2393 -- non-static. This avoids possible cases of infinite recursion where
2394 -- the expander puts in a redundant test and we remove it. Instead we
2395 -- deal with these cases in the expander.
2397 -- Select result operand
2399 if Is_True
(Expr_Value
(Condition
)) then
2400 Result
:= Then_Expr
;
2401 Non_Result
:= Else_Expr
;
2403 Result
:= Else_Expr
;
2404 Non_Result
:= Then_Expr
;
2407 -- Note that it does not matter if the non-result operand raises a
2408 -- Constraint_Error, but if the result raises constraint error then we
2409 -- replace the node with a raise constraint error. This will properly
2410 -- propagate Raises_Constraint_Error since this flag is set in Result.
2412 if Raises_Constraint_Error
(Result
) then
2413 Rewrite_In_Raise_CE
(N
, Result
);
2414 Check_Non_Static_Context
(Non_Result
);
2416 -- Otherwise the result operand replaces the original node
2419 Rewrite
(N
, Relocate_Node
(Result
));
2420 Set_Is_Static_Expression
(N
);
2422 end Eval_If_Expression
;
2424 ----------------------------
2425 -- Eval_Indexed_Component --
2426 ----------------------------
2428 -- Indexed components are never static, so we need to perform the check
2429 -- for non-static context on the index values. Then, we check if the
2430 -- value can be obtained at compile time, even though it is non-static.
2432 procedure Eval_Indexed_Component
(N
: Node_Id
) is
2436 -- Check for non-static context on index values
2438 Expr
:= First
(Expressions
(N
));
2439 while Present
(Expr
) loop
2440 Check_Non_Static_Context
(Expr
);
2444 -- If the indexed component appears in an object renaming declaration
2445 -- then we do not want to try to evaluate it, since in this case we
2446 -- need the identity of the array element.
2448 if Nkind
(Parent
(N
)) = N_Object_Renaming_Declaration
then
2451 -- Similarly if the indexed component appears as the prefix of an
2452 -- attribute we don't want to evaluate it, because at least for
2453 -- some cases of attributes we need the identify (e.g. Access, Size)
2455 elsif Nkind
(Parent
(N
)) = N_Attribute_Reference
then
2459 -- Note: there are other cases, such as the left side of an assignment,
2460 -- or an OUT parameter for a call, where the replacement results in the
2461 -- illegal use of a constant, But these cases are illegal in the first
2462 -- place, so the replacement, though silly, is harmless.
2464 -- Now see if this is a constant array reference
2466 if List_Length
(Expressions
(N
)) = 1
2467 and then Is_Entity_Name
(Prefix
(N
))
2468 and then Ekind
(Entity
(Prefix
(N
))) = E_Constant
2469 and then Present
(Constant_Value
(Entity
(Prefix
(N
))))
2472 Loc
: constant Source_Ptr
:= Sloc
(N
);
2473 Arr
: constant Node_Id
:= Constant_Value
(Entity
(Prefix
(N
)));
2474 Sub
: constant Node_Id
:= First
(Expressions
(N
));
2480 -- Linear one's origin subscript value for array reference
2483 -- Lower bound of the first array index
2486 -- Value from constant array
2489 Atyp
:= Etype
(Arr
);
2491 if Is_Access_Type
(Atyp
) then
2492 Atyp
:= Designated_Type
(Atyp
);
2495 -- If we have an array type (we should have but perhaps there are
2496 -- error cases where this is not the case), then see if we can do
2497 -- a constant evaluation of the array reference.
2499 if Is_Array_Type
(Atyp
) and then Atyp
/= Any_Composite
then
2500 if Ekind
(Atyp
) = E_String_Literal_Subtype
then
2501 Lbd
:= String_Literal_Low_Bound
(Atyp
);
2503 Lbd
:= Type_Low_Bound
(Etype
(First_Index
(Atyp
)));
2506 if Compile_Time_Known_Value
(Sub
)
2507 and then Nkind
(Arr
) = N_Aggregate
2508 and then Compile_Time_Known_Value
(Lbd
)
2509 and then Is_Discrete_Type
(Component_Type
(Atyp
))
2511 Lin
:= UI_To_Int
(Expr_Value
(Sub
) - Expr_Value
(Lbd
)) + 1;
2513 if List_Length
(Expressions
(Arr
)) >= Lin
then
2514 Elm
:= Pick
(Expressions
(Arr
), Lin
);
2516 -- If the resulting expression is compile time known,
2517 -- then we can rewrite the indexed component with this
2518 -- value, being sure to mark the result as non-static.
2519 -- We also reset the Sloc, in case this generates an
2520 -- error later on (e.g. 136'Access).
2522 if Compile_Time_Known_Value
(Elm
) then
2523 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2524 Set_Is_Static_Expression
(N
, False);
2529 -- We can also constant-fold if the prefix is a string literal.
2530 -- This will be useful in an instantiation or an inlining.
2532 elsif Compile_Time_Known_Value
(Sub
)
2533 and then Nkind
(Arr
) = N_String_Literal
2534 and then Compile_Time_Known_Value
(Lbd
)
2535 and then Expr_Value
(Lbd
) = 1
2536 and then Expr_Value
(Sub
) <=
2537 String_Literal_Length
(Etype
(Arr
))
2540 C
: constant Char_Code
:=
2541 Get_String_Char
(Strval
(Arr
),
2542 UI_To_Int
(Expr_Value
(Sub
)));
2544 Set_Character_Literal_Name
(C
);
2547 Make_Character_Literal
(Loc
,
2549 Char_Literal_Value
=> UI_From_CC
(C
));
2550 Set_Etype
(Elm
, Component_Type
(Atyp
));
2551 Rewrite
(N
, Duplicate_Subexpr_No_Checks
(Elm
));
2552 Set_Is_Static_Expression
(N
, False);
2558 end Eval_Indexed_Component
;
2560 --------------------------
2561 -- Eval_Integer_Literal --
2562 --------------------------
2564 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2565 -- as static by the analyzer. The reason we did it that early is to allow
2566 -- the possibility of turning off the Is_Static_Expression flag after
2567 -- analysis, but before resolution, when integer literals are generated in
2568 -- the expander that do not correspond to static expressions.
2570 procedure Eval_Integer_Literal
(N
: Node_Id
) is
2571 T
: constant Entity_Id
:= Etype
(N
);
2573 function In_Any_Integer_Context
return Boolean;
2574 -- If the literal is resolved with a specific type in a context where
2575 -- the expected type is Any_Integer, there are no range checks on the
2576 -- literal. By the time the literal is evaluated, it carries the type
2577 -- imposed by the enclosing expression, and we must recover the context
2578 -- to determine that Any_Integer is meant.
2580 ----------------------------
2581 -- In_Any_Integer_Context --
2582 ----------------------------
2584 function In_Any_Integer_Context
return Boolean is
2585 Par
: constant Node_Id
:= Parent
(N
);
2586 K
: constant Node_Kind
:= Nkind
(Par
);
2589 -- Any_Integer also appears in digits specifications for real types,
2590 -- but those have bounds smaller that those of any integer base type,
2591 -- so we can safely ignore these cases.
2593 return Nkind_In
(K
, N_Number_Declaration
,
2594 N_Attribute_Reference
,
2595 N_Attribute_Definition_Clause
,
2596 N_Modular_Type_Definition
,
2597 N_Signed_Integer_Type_Definition
);
2598 end In_Any_Integer_Context
;
2600 -- Start of processing for Eval_Integer_Literal
2604 -- If the literal appears in a non-expression context, then it is
2605 -- certainly appearing in a non-static context, so check it. This is
2606 -- actually a redundant check, since Check_Non_Static_Context would
2607 -- check it, but it seems worth while avoiding the call.
2609 if Nkind
(Parent
(N
)) not in N_Subexpr
2610 and then not In_Any_Integer_Context
2612 Check_Non_Static_Context
(N
);
2615 -- Modular integer literals must be in their base range
2617 if Is_Modular_Integer_Type
(T
)
2618 and then Is_Out_Of_Range
(N
, Base_Type
(T
), Assume_Valid
=> True)
2622 end Eval_Integer_Literal
;
2624 ---------------------
2625 -- Eval_Logical_Op --
2626 ---------------------
2628 -- Logical operations are static functions, so the result is potentially
2629 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2631 procedure Eval_Logical_Op
(N
: Node_Id
) is
2632 Left
: constant Node_Id
:= Left_Opnd
(N
);
2633 Right
: constant Node_Id
:= Right_Opnd
(N
);
2638 -- If not foldable we are done
2640 Test_Expression_Is_Foldable
(N
, Left
, Right
, Stat
, Fold
);
2646 -- Compile time evaluation of logical operation
2649 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2650 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2653 if Is_Modular_Integer_Type
(Etype
(N
)) then
2655 Left_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2656 Right_Bits
: Bits
(0 .. UI_To_Int
(Esize
(Etype
(N
))) - 1);
2659 To_Bits
(Left_Int
, Left_Bits
);
2660 To_Bits
(Right_Int
, Right_Bits
);
2662 -- Note: should really be able to use array ops instead of
2663 -- these loops, but they weren't working at the time ???
2665 if Nkind
(N
) = N_Op_And
then
2666 for J
in Left_Bits
'Range loop
2667 Left_Bits
(J
) := Left_Bits
(J
) and Right_Bits
(J
);
2670 elsif Nkind
(N
) = N_Op_Or
then
2671 for J
in Left_Bits
'Range loop
2672 Left_Bits
(J
) := Left_Bits
(J
) or Right_Bits
(J
);
2676 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2678 for J
in Left_Bits
'Range loop
2679 Left_Bits
(J
) := Left_Bits
(J
) xor Right_Bits
(J
);
2683 Fold_Uint
(N
, From_Bits
(Left_Bits
, Etype
(N
)), Stat
);
2687 pragma Assert
(Is_Boolean_Type
(Etype
(N
)));
2689 if Nkind
(N
) = N_Op_And
then
2691 Test
(Is_True
(Left_Int
) and then Is_True
(Right_Int
)), Stat
);
2693 elsif Nkind
(N
) = N_Op_Or
then
2695 Test
(Is_True
(Left_Int
) or else Is_True
(Right_Int
)), Stat
);
2698 pragma Assert
(Nkind
(N
) = N_Op_Xor
);
2700 Test
(Is_True
(Left_Int
) xor Is_True
(Right_Int
)), Stat
);
2704 end Eval_Logical_Op
;
2706 ------------------------
2707 -- Eval_Membership_Op --
2708 ------------------------
2710 -- A membership test is potentially static if the expression is static, and
2711 -- the range is a potentially static range, or is a subtype mark denoting a
2712 -- static subtype (RM 4.9(12)).
2714 procedure Eval_Membership_Op
(N
: Node_Id
) is
2715 Left
: constant Node_Id
:= Left_Opnd
(N
);
2716 Right
: constant Node_Id
:= Right_Opnd
(N
);
2717 Alts
: constant List_Id
:= Alternatives
(N
);
2718 Result
: Match_Result
;
2721 -- Ignore if error in either operand, except to make sure that Any_Type
2722 -- is properly propagated to avoid junk cascaded errors.
2724 if Etype
(Left
) = Any_Type
2725 or else (Present
(Right
) and then Etype
(Right
) = Any_Type
)
2727 Set_Etype
(N
, Any_Type
);
2731 -- Ignore if types involved have predicates
2732 -- Is this right for static predicates ???
2733 -- And what about the alternatives ???
2735 if Present
(Predicate_Function
(Etype
(Left
)))
2736 or else (Present
(Right
)
2737 and then Present
(Predicate_Function
(Etype
(Right
))))
2742 -- If left operand non-static, then nothing to do
2744 if not Is_Static_Expression
(Left
) then
2748 -- If choice is non-static, left operand is in non-static context
2750 if (Present
(Right
) and then not Is_Static_Choice
(Right
))
2751 or else (Present
(Alts
) and then not Is_Static_Choice_List
(Alts
))
2753 Check_Non_Static_Context
(Left
);
2757 -- Otherwise we definitely have a static expression
2759 Set_Is_Static_Expression
(N
);
2761 -- If left operand raises constraint error, propagate and we are done
2763 if Raises_Constraint_Error
(Left
) then
2764 Set_Raises_Constraint_Error
(N
, True);
2769 if Present
(Right
) then
2770 Result
:= Choice_Matches
(Left
, Right
);
2772 Result
:= Choices_Match
(Left
, Alts
);
2775 -- If result is Non_Static, it means that we raise Constraint_Error,
2776 -- since we already tested that the operands were themselves static.
2778 if Result
= Non_Static
then
2779 Set_Raises_Constraint_Error
(N
);
2781 -- Otherwise we have our result (flipped if NOT IN case)
2785 (N
, Test
((Result
= Match
) xor (Nkind
(N
) = N_Not_In
)), True);
2786 Warn_On_Known_Condition
(N
);
2789 end Eval_Membership_Op
;
2791 ------------------------
2792 -- Eval_Named_Integer --
2793 ------------------------
2795 procedure Eval_Named_Integer
(N
: Node_Id
) is
2798 Expr_Value
(Expression
(Declaration_Node
(Entity
(N
)))), True);
2799 end Eval_Named_Integer
;
2801 ---------------------
2802 -- Eval_Named_Real --
2803 ---------------------
2805 procedure Eval_Named_Real
(N
: Node_Id
) is
2808 Expr_Value_R
(Expression
(Declaration_Node
(Entity
(N
)))), True);
2809 end Eval_Named_Real
;
2815 -- Exponentiation is a static functions, so the result is potentially
2816 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2818 procedure Eval_Op_Expon
(N
: Node_Id
) is
2819 Left
: constant Node_Id
:= Left_Opnd
(N
);
2820 Right
: constant Node_Id
:= Right_Opnd
(N
);
2825 -- If not foldable we are done
2827 Test_Expression_Is_Foldable
2828 (N
, Left
, Right
, Stat
, Fold
, CRT_Safe
=> True);
2830 -- Return if not foldable
2836 if Configurable_Run_Time_Mode
and not Stat
then
2840 -- Fold exponentiation operation
2843 Right_Int
: constant Uint
:= Expr_Value
(Right
);
2848 if Is_Integer_Type
(Etype
(Left
)) then
2850 Left_Int
: constant Uint
:= Expr_Value
(Left
);
2854 -- Exponentiation of an integer raises Constraint_Error for a
2855 -- negative exponent (RM 4.5.6).
2857 if Right_Int
< 0 then
2858 Apply_Compile_Time_Constraint_Error
2859 (N
, "integer exponent negative", CE_Range_Check_Failed
,
2864 if OK_Bits
(N
, Num_Bits
(Left_Int
) * Right_Int
) then
2865 Result
:= Left_Int
** Right_Int
;
2870 if Is_Modular_Integer_Type
(Etype
(N
)) then
2871 Result
:= Result
mod Modulus
(Etype
(N
));
2874 Fold_Uint
(N
, Result
, Stat
);
2882 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
2885 -- Cannot have a zero base with a negative exponent
2887 if UR_Is_Zero
(Left_Real
) then
2889 if Right_Int
< 0 then
2890 Apply_Compile_Time_Constraint_Error
2891 (N
, "zero ** negative integer", CE_Range_Check_Failed
,
2895 Fold_Ureal
(N
, Ureal_0
, Stat
);
2899 Fold_Ureal
(N
, Left_Real
** Right_Int
, Stat
);
2910 -- The not operation is a static functions, so the result is potentially
2911 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
2913 procedure Eval_Op_Not
(N
: Node_Id
) is
2914 Right
: constant Node_Id
:= Right_Opnd
(N
);
2919 -- If not foldable we are done
2921 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
2927 -- Fold not operation
2930 Rint
: constant Uint
:= Expr_Value
(Right
);
2931 Typ
: constant Entity_Id
:= Etype
(N
);
2934 -- Negation is equivalent to subtracting from the modulus minus one.
2935 -- For a binary modulus this is equivalent to the ones-complement of
2936 -- the original value. For non-binary modulus this is an arbitrary
2937 -- but consistent definition.
2939 if Is_Modular_Integer_Type
(Typ
) then
2940 Fold_Uint
(N
, Modulus
(Typ
) - 1 - Rint
, Stat
);
2941 else pragma Assert
(Is_Boolean_Type
(Typ
));
2942 Fold_Uint
(N
, Test
(not Is_True
(Rint
)), Stat
);
2945 Set_Is_Static_Expression
(N
, Stat
);
2949 -------------------------------
2950 -- Eval_Qualified_Expression --
2951 -------------------------------
2953 -- A qualified expression is potentially static if its subtype mark denotes
2954 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2956 procedure Eval_Qualified_Expression
(N
: Node_Id
) is
2957 Operand
: constant Node_Id
:= Expression
(N
);
2958 Target_Type
: constant Entity_Id
:= Entity
(Subtype_Mark
(N
));
2965 -- Can only fold if target is string or scalar and subtype is static.
2966 -- Also, do not fold if our parent is an allocator (this is because the
2967 -- qualified expression is really part of the syntactic structure of an
2968 -- allocator, and we do not want to end up with something that
2969 -- corresponds to "new 1" where the 1 is the result of folding a
2970 -- qualified expression).
2972 if not Is_Static_Subtype
(Target_Type
)
2973 or else Nkind
(Parent
(N
)) = N_Allocator
2975 Check_Non_Static_Context
(Operand
);
2977 -- If operand is known to raise constraint_error, set the flag on the
2978 -- expression so it does not get optimized away.
2980 if Nkind
(Operand
) = N_Raise_Constraint_Error
then
2981 Set_Raises_Constraint_Error
(N
);
2987 -- If not foldable we are done
2989 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
2994 -- Don't try fold if target type has constraint error bounds
2996 elsif not Is_OK_Static_Subtype
(Target_Type
) then
2997 Set_Raises_Constraint_Error
(N
);
3001 -- Here we will fold, save Print_In_Hex indication
3003 Hex
:= Nkind
(Operand
) = N_Integer_Literal
3004 and then Print_In_Hex
(Operand
);
3006 -- Fold the result of qualification
3008 if Is_Discrete_Type
(Target_Type
) then
3009 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
3011 -- Preserve Print_In_Hex indication
3013 if Hex
and then Nkind
(N
) = N_Integer_Literal
then
3014 Set_Print_In_Hex
(N
);
3017 elsif Is_Real_Type
(Target_Type
) then
3018 Fold_Ureal
(N
, Expr_Value_R
(Operand
), Stat
);
3021 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Stat
);
3024 Set_Is_Static_Expression
(N
, False);
3026 Check_String_Literal_Length
(N
, Target_Type
);
3032 -- The expression may be foldable but not static
3034 Set_Is_Static_Expression
(N
, Stat
);
3036 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
3039 end Eval_Qualified_Expression
;
3041 -----------------------
3042 -- Eval_Real_Literal --
3043 -----------------------
3045 -- Numeric literals are static (RM 4.9(1)), and have already been marked
3046 -- as static by the analyzer. The reason we did it that early is to allow
3047 -- the possibility of turning off the Is_Static_Expression flag after
3048 -- analysis, but before resolution, when integer literals are generated
3049 -- in the expander that do not correspond to static expressions.
3051 procedure Eval_Real_Literal
(N
: Node_Id
) is
3052 PK
: constant Node_Kind
:= Nkind
(Parent
(N
));
3055 -- If the literal appears in a non-expression context and not as part of
3056 -- a number declaration, then it is appearing in a non-static context,
3059 if PK
not in N_Subexpr
and then PK
/= N_Number_Declaration
then
3060 Check_Non_Static_Context
(N
);
3062 end Eval_Real_Literal
;
3064 ------------------------
3065 -- Eval_Relational_Op --
3066 ------------------------
3068 -- Relational operations are static functions, so the result is static if
3069 -- both operands are static (RM 4.9(7), 4.9(20)), except that for strings,
3070 -- the result is never static, even if the operands are.
3072 -- However, for internally generated nodes, we allow string equality and
3073 -- inequality to be static. This is because we rewrite A in "ABC" as an
3074 -- equality test A = "ABC", and the former is definitely static.
3076 procedure Eval_Relational_Op
(N
: Node_Id
) is
3077 Left
: constant Node_Id
:= Left_Opnd
(N
);
3078 Right
: constant Node_Id
:= Right_Opnd
(N
);
3079 Typ
: constant Entity_Id
:= Etype
(Left
);
3080 Otype
: Entity_Id
:= Empty
;
3084 -- One special case to deal with first. If we can tell that the result
3085 -- will be false because the lengths of one or more index subtypes are
3086 -- compile time known and different, then we can replace the entire
3087 -- result by False. We only do this for one dimensional arrays, because
3088 -- the case of multi-dimensional arrays is rare and too much trouble. If
3089 -- one of the operands is an illegal aggregate, its type might still be
3090 -- an arbitrary composite type, so nothing to do.
3092 if Is_Array_Type
(Typ
)
3093 and then Typ
/= Any_Composite
3094 and then Number_Dimensions
(Typ
) = 1
3095 and then (Nkind
(N
) = N_Op_Eq
or else Nkind
(N
) = N_Op_Ne
)
3097 if Raises_Constraint_Error
(Left
)
3099 Raises_Constraint_Error
(Right
)
3104 -- OK, we have the case where we may be able to do this fold
3106 Length_Mismatch
: declare
3107 procedure Get_Static_Length
(Op
: Node_Id
; Len
: out Uint
);
3108 -- If Op is an expression for a constrained array with a known at
3109 -- compile time length, then Len is set to this (non-negative
3110 -- length). Otherwise Len is set to minus 1.
3112 -----------------------
3113 -- Get_Static_Length --
3114 -----------------------
3116 procedure Get_Static_Length
(Op
: Node_Id
; Len
: out Uint
) is
3120 -- First easy case string literal
3122 if Nkind
(Op
) = N_String_Literal
then
3123 Len
:= UI_From_Int
(String_Length
(Strval
(Op
)));
3127 -- Second easy case, not constrained subtype, so no length
3129 if not Is_Constrained
(Etype
(Op
)) then
3130 Len
:= Uint_Minus_1
;
3136 T
:= Etype
(First_Index
(Etype
(Op
)));
3138 -- The simple case, both bounds are known at compile time
3140 if Is_Discrete_Type
(T
)
3141 and then Compile_Time_Known_Value
(Type_Low_Bound
(T
))
3142 and then Compile_Time_Known_Value
(Type_High_Bound
(T
))
3144 Len
:= UI_Max
(Uint_0
,
3145 Expr_Value
(Type_High_Bound
(T
)) -
3146 Expr_Value
(Type_Low_Bound
(T
)) + 1);
3150 -- A more complex case, where the bounds are of the form
3151 -- X [+/- K1] .. X [+/- K2]), where X is an expression that is
3152 -- either A'First or A'Last (with A an entity name), or X is an
3153 -- entity name, and the two X's are the same and K1 and K2 are
3154 -- known at compile time, in this case, the length can also be
3155 -- computed at compile time, even though the bounds are not
3156 -- known. A common case of this is e.g. (X'First .. X'First+5).
3158 Extract_Length
: declare
3159 procedure Decompose_Expr
3161 Ent
: out Entity_Id
;
3162 Kind
: out Character;
3164 -- Given an expression see if it is of the form given above,
3165 -- X [+/- K]. If so Ent is set to the entity in X, Kind is
3166 -- 'F','L','E' for 'First/'Last/simple entity, and Cons is
3167 -- the value of K. If the expression is not of the required
3168 -- form, Ent is set to Empty.
3170 --------------------
3171 -- Decompose_Expr --
3172 --------------------
3174 procedure Decompose_Expr
3176 Ent
: out Entity_Id
;
3177 Kind
: out Character;
3183 if Nkind
(Expr
) = N_Op_Add
3184 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
3186 Exp
:= Left_Opnd
(Expr
);
3187 Cons
:= Expr_Value
(Right_Opnd
(Expr
));
3189 elsif Nkind
(Expr
) = N_Op_Subtract
3190 and then Compile_Time_Known_Value
(Right_Opnd
(Expr
))
3192 Exp
:= Left_Opnd
(Expr
);
3193 Cons
:= -Expr_Value
(Right_Opnd
(Expr
));
3195 -- If the bound is a constant created to remove side
3196 -- effects, recover original expression to see if it has
3197 -- one of the recognizable forms.
3199 elsif Nkind
(Expr
) = N_Identifier
3200 and then not Comes_From_Source
(Entity
(Expr
))
3201 and then Ekind
(Entity
(Expr
)) = E_Constant
3203 Nkind
(Parent
(Entity
(Expr
))) = N_Object_Declaration
3205 Exp
:= Expression
(Parent
(Entity
(Expr
)));
3206 Decompose_Expr
(Exp
, Ent
, Kind
, Cons
);
3208 -- If original expression includes an entity, create a
3209 -- reference to it for use below.
3211 if Present
(Ent
) then
3212 Exp
:= New_Occurrence_Of
(Ent
, Sloc
(Ent
));
3220 -- At this stage Exp is set to the potential X
3222 if Nkind
(Exp
) = N_Attribute_Reference
then
3223 if Attribute_Name
(Exp
) = Name_First
then
3225 elsif Attribute_Name
(Exp
) = Name_Last
then
3232 Exp
:= Prefix
(Exp
);
3238 if Is_Entity_Name
(Exp
) and then Present
(Entity
(Exp
))
3240 Ent
:= Entity
(Exp
);
3248 Ent1
, Ent2
: Entity_Id
;
3249 Kind1
, Kind2
: Character;
3250 Cons1
, Cons2
: Uint
;
3252 -- Start of processing for Extract_Length
3256 (Original_Node
(Type_Low_Bound
(T
)), Ent1
, Kind1
, Cons1
);
3258 (Original_Node
(Type_High_Bound
(T
)), Ent2
, Kind2
, Cons2
);
3261 and then Kind1
= Kind2
3262 and then Ent1
= Ent2
3264 Len
:= Cons2
- Cons1
+ 1;
3266 Len
:= Uint_Minus_1
;
3269 end Get_Static_Length
;
3276 -- Start of processing for Length_Mismatch
3279 Get_Static_Length
(Left
, Len_L
);
3280 Get_Static_Length
(Right
, Len_R
);
3282 if Len_L
/= Uint_Minus_1
3283 and then Len_R
/= Uint_Minus_1
3284 and then Len_L
/= Len_R
3286 Fold_Uint
(N
, Test
(Nkind
(N
) = N_Op_Ne
), False);
3287 Warn_On_Known_Condition
(N
);
3290 end Length_Mismatch
;
3294 Is_Static_Expression
: Boolean;
3296 Is_Foldable
: Boolean;
3297 pragma Unreferenced
(Is_Foldable
);
3300 -- Initialize the value of Is_Static_Expression. The value of
3301 -- Is_Foldable returned by Test_Expression_Is_Foldable is not needed
3302 -- since, even when some operand is a variable, we can still perform
3303 -- the static evaluation of the expression in some cases (for
3304 -- example, for a variable of a subtype of Integer we statically
3305 -- know that any value stored in such variable is smaller than
3308 Test_Expression_Is_Foldable
3309 (N
, Left
, Right
, Is_Static_Expression
, Is_Foldable
);
3311 -- Only comparisons of scalars can give static results. In
3312 -- particular, comparisons of strings never yield a static
3313 -- result, even if both operands are static strings, except that
3314 -- as noted above, we allow equality/inequality for strings.
3316 if Is_String_Type
(Typ
)
3317 and then not Comes_From_Source
(N
)
3318 and then Nkind_In
(N
, N_Op_Eq
, N_Op_Ne
)
3322 elsif not Is_Scalar_Type
(Typ
) then
3323 Is_Static_Expression
:= False;
3324 Set_Is_Static_Expression
(N
, False);
3327 -- For operators on universal numeric types called as functions with
3328 -- an explicit scope, determine appropriate specific numeric type,
3329 -- and diagnose possible ambiguity.
3331 if Is_Universal_Numeric_Type
(Etype
(Left
))
3333 Is_Universal_Numeric_Type
(Etype
(Right
))
3335 Otype
:= Find_Universal_Operator_Type
(N
);
3338 -- For static real type expressions, do not use Compile_Time_Compare
3339 -- since it worries about run-time results which are not exact.
3341 if Is_Static_Expression
and then Is_Real_Type
(Typ
) then
3343 Left_Real
: constant Ureal
:= Expr_Value_R
(Left
);
3344 Right_Real
: constant Ureal
:= Expr_Value_R
(Right
);
3348 when N_Op_Eq
=> Result
:= (Left_Real
= Right_Real
);
3349 when N_Op_Ne
=> Result
:= (Left_Real
/= Right_Real
);
3350 when N_Op_Lt
=> Result
:= (Left_Real
< Right_Real
);
3351 when N_Op_Le
=> Result
:= (Left_Real
<= Right_Real
);
3352 when N_Op_Gt
=> Result
:= (Left_Real
> Right_Real
);
3353 when N_Op_Ge
=> Result
:= (Left_Real
>= Right_Real
);
3356 raise Program_Error
;
3359 Fold_Uint
(N
, Test
(Result
), True);
3362 -- For all other cases, we use Compile_Time_Compare to do the compare
3366 CR
: constant Compare_Result
:=
3367 Compile_Time_Compare
3368 (Left
, Right
, Assume_Valid
=> False);
3371 if CR
= Unknown
then
3379 elsif CR
= NE
or else CR
= GT
or else CR
= LT
then
3386 if CR
= NE
or else CR
= GT
or else CR
= LT
then
3397 elsif CR
= EQ
or else CR
= GT
or else CR
= GE
then
3404 if CR
= LT
or else CR
= EQ
or else CR
= LE
then
3415 elsif CR
= EQ
or else CR
= LT
or else CR
= LE
then
3422 if CR
= GT
or else CR
= EQ
or else CR
= GE
then
3431 raise Program_Error
;
3435 Fold_Uint
(N
, Test
(Result
), Is_Static_Expression
);
3439 -- For the case of a folded relational operator on a specific numeric
3440 -- type, freeze operand type now.
3442 if Present
(Otype
) then
3443 Freeze_Before
(N
, Otype
);
3446 Warn_On_Known_Condition
(N
);
3447 end Eval_Relational_Op
;
3453 -- Shift operations are intrinsic operations that can never be static, so
3454 -- the only processing required is to perform the required check for a non
3455 -- static context for the two operands.
3457 -- Actually we could do some compile time evaluation here some time ???
3459 procedure Eval_Shift
(N
: Node_Id
) is
3461 Check_Non_Static_Context
(Left_Opnd
(N
));
3462 Check_Non_Static_Context
(Right_Opnd
(N
));
3465 ------------------------
3466 -- Eval_Short_Circuit --
3467 ------------------------
3469 -- A short circuit operation is potentially static if both operands are
3470 -- potentially static (RM 4.9 (13)).
3472 procedure Eval_Short_Circuit
(N
: Node_Id
) is
3473 Kind
: constant Node_Kind
:= Nkind
(N
);
3474 Left
: constant Node_Id
:= Left_Opnd
(N
);
3475 Right
: constant Node_Id
:= Right_Opnd
(N
);
3478 Rstat
: constant Boolean :=
3479 Is_Static_Expression
(Left
)
3481 Is_Static_Expression
(Right
);
3484 -- Short circuit operations are never static in Ada 83
3486 if Ada_Version
= Ada_83
and then Comes_From_Source
(N
) then
3487 Check_Non_Static_Context
(Left
);
3488 Check_Non_Static_Context
(Right
);
3492 -- Now look at the operands, we can't quite use the normal call to
3493 -- Test_Expression_Is_Foldable here because short circuit operations
3494 -- are a special case, they can still be foldable, even if the right
3495 -- operand raises constraint error.
3497 -- If either operand is Any_Type, just propagate to result and do not
3498 -- try to fold, this prevents cascaded errors.
3500 if Etype
(Left
) = Any_Type
or else Etype
(Right
) = Any_Type
then
3501 Set_Etype
(N
, Any_Type
);
3504 -- If left operand raises constraint error, then replace node N with
3505 -- the raise constraint error node, and we are obviously not foldable.
3506 -- Is_Static_Expression is set from the two operands in the normal way,
3507 -- and we check the right operand if it is in a non-static context.
3509 elsif Raises_Constraint_Error
(Left
) then
3511 Check_Non_Static_Context
(Right
);
3514 Rewrite_In_Raise_CE
(N
, Left
);
3515 Set_Is_Static_Expression
(N
, Rstat
);
3518 -- If the result is not static, then we won't in any case fold
3520 elsif not Rstat
then
3521 Check_Non_Static_Context
(Left
);
3522 Check_Non_Static_Context
(Right
);
3526 -- Here the result is static, note that, unlike the normal processing
3527 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
3528 -- the right operand raises constraint error, that's because it is not
3529 -- significant if the left operand is decisive.
3531 Set_Is_Static_Expression
(N
);
3533 -- It does not matter if the right operand raises constraint error if
3534 -- it will not be evaluated. So deal specially with the cases where
3535 -- the right operand is not evaluated. Note that we will fold these
3536 -- cases even if the right operand is non-static, which is fine, but
3537 -- of course in these cases the result is not potentially static.
3539 Left_Int
:= Expr_Value
(Left
);
3541 if (Kind
= N_And_Then
and then Is_False
(Left_Int
))
3543 (Kind
= N_Or_Else
and then Is_True
(Left_Int
))
3545 Fold_Uint
(N
, Left_Int
, Rstat
);
3549 -- If first operand not decisive, then it does matter if the right
3550 -- operand raises constraint error, since it will be evaluated, so
3551 -- we simply replace the node with the right operand. Note that this
3552 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
3553 -- (both are set to True in Right).
3555 if Raises_Constraint_Error
(Right
) then
3556 Rewrite_In_Raise_CE
(N
, Right
);
3557 Check_Non_Static_Context
(Left
);
3561 -- Otherwise the result depends on the right operand
3563 Fold_Uint
(N
, Expr_Value
(Right
), Rstat
);
3565 end Eval_Short_Circuit
;
3571 -- Slices can never be static, so the only processing required is to check
3572 -- for non-static context if an explicit range is given.
3574 procedure Eval_Slice
(N
: Node_Id
) is
3575 Drange
: constant Node_Id
:= Discrete_Range
(N
);
3578 if Nkind
(Drange
) = N_Range
then
3579 Check_Non_Static_Context
(Low_Bound
(Drange
));
3580 Check_Non_Static_Context
(High_Bound
(Drange
));
3583 -- A slice of the form A (subtype), when the subtype is the index of
3584 -- the type of A, is redundant, the slice can be replaced with A, and
3585 -- this is worth a warning.
3587 if Is_Entity_Name
(Prefix
(N
)) then
3589 E
: constant Entity_Id
:= Entity
(Prefix
(N
));
3590 T
: constant Entity_Id
:= Etype
(E
);
3593 if Ekind
(E
) = E_Constant
3594 and then Is_Array_Type
(T
)
3595 and then Is_Entity_Name
(Drange
)
3597 if Is_Entity_Name
(Original_Node
(First_Index
(T
)))
3598 and then Entity
(Original_Node
(First_Index
(T
)))
3601 if Warn_On_Redundant_Constructs
then
3602 Error_Msg_N
("redundant slice denotes whole array?r?", N
);
3605 -- The following might be a useful optimization???
3607 -- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
3614 -------------------------
3615 -- Eval_String_Literal --
3616 -------------------------
3618 procedure Eval_String_Literal
(N
: Node_Id
) is
3619 Typ
: constant Entity_Id
:= Etype
(N
);
3620 Bas
: constant Entity_Id
:= Base_Type
(Typ
);
3626 -- Nothing to do if error type (handles cases like default expressions
3627 -- or generics where we have not yet fully resolved the type).
3629 if Bas
= Any_Type
or else Bas
= Any_String
then
3633 -- String literals are static if the subtype is static (RM 4.9(2)), so
3634 -- reset the static expression flag (it was set unconditionally in
3635 -- Analyze_String_Literal) if the subtype is non-static. We tell if
3636 -- the subtype is static by looking at the lower bound.
3638 if Ekind
(Typ
) = E_String_Literal_Subtype
then
3639 if not Is_OK_Static_Expression
(String_Literal_Low_Bound
(Typ
)) then
3640 Set_Is_Static_Expression
(N
, False);
3644 -- Here if Etype of string literal is normal Etype (not yet possible,
3645 -- but may be possible in future).
3647 elsif not Is_OK_Static_Expression
3648 (Type_Low_Bound
(Etype
(First_Index
(Typ
))))
3650 Set_Is_Static_Expression
(N
, False);
3654 -- If original node was a type conversion, then result if non-static
3656 if Nkind
(Original_Node
(N
)) = N_Type_Conversion
then
3657 Set_Is_Static_Expression
(N
, False);
3661 -- Test for illegal Ada 95 cases. A string literal is illegal in Ada 95
3662 -- if its bounds are outside the index base type and this index type is
3663 -- static. This can happen in only two ways. Either the string literal
3664 -- is too long, or it is null, and the lower bound is type'First. Either
3665 -- way it is the upper bound that is out of range of the index type.
3667 if Ada_Version
>= Ada_95
then
3668 if Is_Standard_String_Type
(Bas
) then
3669 Xtp
:= Standard_Positive
;
3671 Xtp
:= Etype
(First_Index
(Bas
));
3674 if Ekind
(Typ
) = E_String_Literal_Subtype
then
3675 Lo
:= String_Literal_Low_Bound
(Typ
);
3677 Lo
:= Type_Low_Bound
(Etype
(First_Index
(Typ
)));
3680 -- Check for string too long
3682 Len
:= String_Length
(Strval
(N
));
3684 if UI_From_Int
(Len
) > String_Type_Len
(Bas
) then
3686 -- Issue message. Note that this message is a warning if the
3687 -- string literal is not marked as static (happens in some cases
3688 -- of folding strings known at compile time, but not static).
3689 -- Furthermore in such cases, we reword the message, since there
3690 -- is no string literal in the source program.
3692 if Is_Static_Expression
(N
) then
3693 Apply_Compile_Time_Constraint_Error
3694 (N
, "string literal too long for}", CE_Length_Check_Failed
,
3696 Typ
=> First_Subtype
(Bas
));
3698 Apply_Compile_Time_Constraint_Error
3699 (N
, "string value too long for}", CE_Length_Check_Failed
,
3701 Typ
=> First_Subtype
(Bas
),
3705 -- Test for null string not allowed
3708 and then not Is_Generic_Type
(Xtp
)
3710 Expr_Value
(Lo
) = Expr_Value
(Type_Low_Bound
(Base_Type
(Xtp
)))
3712 -- Same specialization of message
3714 if Is_Static_Expression
(N
) then
3715 Apply_Compile_Time_Constraint_Error
3716 (N
, "null string literal not allowed for}",
3717 CE_Length_Check_Failed
,
3719 Typ
=> First_Subtype
(Bas
));
3721 Apply_Compile_Time_Constraint_Error
3722 (N
, "null string value not allowed for}",
3723 CE_Length_Check_Failed
,
3725 Typ
=> First_Subtype
(Bas
),
3730 end Eval_String_Literal
;
3732 --------------------------
3733 -- Eval_Type_Conversion --
3734 --------------------------
3736 -- A type conversion is potentially static if its subtype mark is for a
3737 -- static scalar subtype, and its operand expression is potentially static
3740 procedure Eval_Type_Conversion
(N
: Node_Id
) is
3741 Operand
: constant Node_Id
:= Expression
(N
);
3742 Source_Type
: constant Entity_Id
:= Etype
(Operand
);
3743 Target_Type
: constant Entity_Id
:= Etype
(N
);
3748 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean;
3749 -- Returns true if type T is an integer type, or if it is a fixed-point
3750 -- type to be treated as an integer (i.e. the flag Conversion_OK is set
3751 -- on the conversion node).
3753 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean;
3754 -- Returns true if type T is a floating-point type, or if it is a
3755 -- fixed-point type that is not to be treated as an integer (i.e. the
3756 -- flag Conversion_OK is not set on the conversion node).
3758 ------------------------------
3759 -- To_Be_Treated_As_Integer --
3760 ------------------------------
3762 function To_Be_Treated_As_Integer
(T
: Entity_Id
) return Boolean is
3766 or else (Is_Fixed_Point_Type
(T
) and then Conversion_OK
(N
));
3767 end To_Be_Treated_As_Integer
;
3769 ---------------------------
3770 -- To_Be_Treated_As_Real --
3771 ---------------------------
3773 function To_Be_Treated_As_Real
(T
: Entity_Id
) return Boolean is
3776 Is_Floating_Point_Type
(T
)
3777 or else (Is_Fixed_Point_Type
(T
) and then not Conversion_OK
(N
));
3778 end To_Be_Treated_As_Real
;
3780 -- Start of processing for Eval_Type_Conversion
3783 -- Cannot fold if target type is non-static or if semantic error
3785 if not Is_Static_Subtype
(Target_Type
) then
3786 Check_Non_Static_Context
(Operand
);
3788 elsif Error_Posted
(N
) then
3792 -- If not foldable we are done
3794 Test_Expression_Is_Foldable
(N
, Operand
, Stat
, Fold
);
3799 -- Don't try fold if target type has constraint error bounds
3801 elsif not Is_OK_Static_Subtype
(Target_Type
) then
3802 Set_Raises_Constraint_Error
(N
);
3806 -- Remaining processing depends on operand types. Note that in the
3807 -- following type test, fixed-point counts as real unless the flag
3808 -- Conversion_OK is set, in which case it counts as integer.
3810 -- Fold conversion, case of string type. The result is not static
3812 if Is_String_Type
(Target_Type
) then
3813 Fold_Str
(N
, Strval
(Get_String_Val
(Operand
)), Static
=> False);
3816 -- Fold conversion, case of integer target type
3818 elsif To_Be_Treated_As_Integer
(Target_Type
) then
3823 -- Integer to integer conversion
3825 if To_Be_Treated_As_Integer
(Source_Type
) then
3826 Result
:= Expr_Value
(Operand
);
3828 -- Real to integer conversion
3831 Result
:= UR_To_Uint
(Expr_Value_R
(Operand
));
3834 -- If fixed-point type (Conversion_OK must be set), then the
3835 -- result is logically an integer, but we must replace the
3836 -- conversion with the corresponding real literal, since the
3837 -- type from a semantic point of view is still fixed-point.
3839 if Is_Fixed_Point_Type
(Target_Type
) then
3841 (N
, UR_From_Uint
(Result
) * Small_Value
(Target_Type
), Stat
);
3843 -- Otherwise result is integer literal
3846 Fold_Uint
(N
, Result
, Stat
);
3850 -- Fold conversion, case of real target type
3852 elsif To_Be_Treated_As_Real
(Target_Type
) then
3857 if To_Be_Treated_As_Real
(Source_Type
) then
3858 Result
:= Expr_Value_R
(Operand
);
3860 Result
:= UR_From_Uint
(Expr_Value
(Operand
));
3863 Fold_Ureal
(N
, Result
, Stat
);
3866 -- Enumeration types
3869 Fold_Uint
(N
, Expr_Value
(Operand
), Stat
);
3872 if Is_Out_Of_Range
(N
, Etype
(N
), Assume_Valid
=> True) then
3876 end Eval_Type_Conversion
;
3882 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
3883 -- are potentially static if the operand is potentially static (RM 4.9(7)).
3885 procedure Eval_Unary_Op
(N
: Node_Id
) is
3886 Right
: constant Node_Id
:= Right_Opnd
(N
);
3887 Otype
: Entity_Id
:= Empty
;
3892 -- If not foldable we are done
3894 Test_Expression_Is_Foldable
(N
, Right
, Stat
, Fold
);
3900 if Etype
(Right
) = Universal_Integer
3902 Etype
(Right
) = Universal_Real
3904 Otype
:= Find_Universal_Operator_Type
(N
);
3907 -- Fold for integer case
3909 if Is_Integer_Type
(Etype
(N
)) then
3911 Rint
: constant Uint
:= Expr_Value
(Right
);
3915 -- In the case of modular unary plus and abs there is no need
3916 -- to adjust the result of the operation since if the original
3917 -- operand was in bounds the result will be in the bounds of the
3918 -- modular type. However, in the case of modular unary minus the
3919 -- result may go out of the bounds of the modular type and needs
3922 if Nkind
(N
) = N_Op_Plus
then
3925 elsif Nkind
(N
) = N_Op_Minus
then
3926 if Is_Modular_Integer_Type
(Etype
(N
)) then
3927 Result
:= (-Rint
) mod Modulus
(Etype
(N
));
3933 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
3937 Fold_Uint
(N
, Result
, Stat
);
3940 -- Fold for real case
3942 elsif Is_Real_Type
(Etype
(N
)) then
3944 Rreal
: constant Ureal
:= Expr_Value_R
(Right
);
3948 if Nkind
(N
) = N_Op_Plus
then
3950 elsif Nkind
(N
) = N_Op_Minus
then
3951 Result
:= UR_Negate
(Rreal
);
3953 pragma Assert
(Nkind
(N
) = N_Op_Abs
);
3954 Result
:= abs Rreal
;
3957 Fold_Ureal
(N
, Result
, Stat
);
3961 -- If the operator was resolved to a specific type, make sure that type
3962 -- is frozen even if the expression is folded into a literal (which has
3963 -- a universal type).
3965 if Present
(Otype
) then
3966 Freeze_Before
(N
, Otype
);
3970 -------------------------------
3971 -- Eval_Unchecked_Conversion --
3972 -------------------------------
3974 -- Unchecked conversions can never be static, so the only required
3975 -- processing is to check for a non-static context for the operand.
3977 procedure Eval_Unchecked_Conversion
(N
: Node_Id
) is
3979 Check_Non_Static_Context
(Expression
(N
));
3980 end Eval_Unchecked_Conversion
;
3982 --------------------
3983 -- Expr_Rep_Value --
3984 --------------------
3986 function Expr_Rep_Value
(N
: Node_Id
) return Uint
is
3987 Kind
: constant Node_Kind
:= Nkind
(N
);
3991 if Is_Entity_Name
(N
) then
3994 -- An enumeration literal that was either in the source or created
3995 -- as a result of static evaluation.
3997 if Ekind
(Ent
) = E_Enumeration_Literal
then
3998 return Enumeration_Rep
(Ent
);
4000 -- A user defined static constant
4003 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4004 return Expr_Rep_Value
(Constant_Value
(Ent
));
4007 -- An integer literal that was either in the source or created as a
4008 -- result of static evaluation.
4010 elsif Kind
= N_Integer_Literal
then
4013 -- A real literal for a fixed-point type. This must be the fixed-point
4014 -- case, either the literal is of a fixed-point type, or it is a bound
4015 -- of a fixed-point type, with type universal real. In either case we
4016 -- obtain the desired value from Corresponding_Integer_Value.
4018 elsif Kind
= N_Real_Literal
then
4019 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
4020 return Corresponding_Integer_Value
(N
);
4022 -- Otherwise must be character literal
4025 pragma Assert
(Kind
= N_Character_Literal
);
4028 -- Since Character literals of type Standard.Character don't have any
4029 -- defining character literals built for them, they do not have their
4030 -- Entity set, so just use their Char code. Otherwise for user-
4031 -- defined character literals use their Pos value as usual which is
4032 -- the same as the Rep value.
4035 return Char_Literal_Value
(N
);
4037 return Enumeration_Rep
(Ent
);
4046 function Expr_Value
(N
: Node_Id
) return Uint
is
4047 Kind
: constant Node_Kind
:= Nkind
(N
);
4048 CV_Ent
: CV_Entry
renames CV_Cache
(Nat
(N
) mod CV_Cache_Size
);
4053 -- If already in cache, then we know it's compile time known and we can
4054 -- return the value that was previously stored in the cache since
4055 -- compile time known values cannot change.
4057 if CV_Ent
.N
= N
then
4061 -- Otherwise proceed to test value
4063 if Is_Entity_Name
(N
) then
4066 -- An enumeration literal that was either in the source or created as
4067 -- a result of static evaluation.
4069 if Ekind
(Ent
) = E_Enumeration_Literal
then
4070 Val
:= Enumeration_Pos
(Ent
);
4072 -- A user defined static constant
4075 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4076 Val
:= Expr_Value
(Constant_Value
(Ent
));
4079 -- An integer literal that was either in the source or created as a
4080 -- result of static evaluation.
4082 elsif Kind
= N_Integer_Literal
then
4085 -- A real literal for a fixed-point type. This must be the fixed-point
4086 -- case, either the literal is of a fixed-point type, or it is a bound
4087 -- of a fixed-point type, with type universal real. In either case we
4088 -- obtain the desired value from Corresponding_Integer_Value.
4090 elsif Kind
= N_Real_Literal
then
4091 pragma Assert
(Is_Fixed_Point_Type
(Underlying_Type
(Etype
(N
))));
4092 Val
:= Corresponding_Integer_Value
(N
);
4094 -- Otherwise must be character literal
4097 pragma Assert
(Kind
= N_Character_Literal
);
4100 -- Since Character literals of type Standard.Character don't
4101 -- have any defining character literals built for them, they
4102 -- do not have their Entity set, so just use their Char
4103 -- code. Otherwise for user-defined character literals use
4104 -- their Pos value as usual.
4107 Val
:= Char_Literal_Value
(N
);
4109 Val
:= Enumeration_Pos
(Ent
);
4113 -- Come here with Val set to value to be returned, set cache
4124 function Expr_Value_E
(N
: Node_Id
) return Entity_Id
is
4125 Ent
: constant Entity_Id
:= Entity
(N
);
4127 if Ekind
(Ent
) = E_Enumeration_Literal
then
4130 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4131 return Expr_Value_E
(Constant_Value
(Ent
));
4139 function Expr_Value_R
(N
: Node_Id
) return Ureal
is
4140 Kind
: constant Node_Kind
:= Nkind
(N
);
4144 if Kind
= N_Real_Literal
then
4147 elsif Kind
= N_Identifier
or else Kind
= N_Expanded_Name
then
4149 pragma Assert
(Ekind
(Ent
) = E_Constant
);
4150 return Expr_Value_R
(Constant_Value
(Ent
));
4152 elsif Kind
= N_Integer_Literal
then
4153 return UR_From_Uint
(Expr_Value
(N
));
4155 -- Here, we have a node that cannot be interpreted as a compile time
4156 -- constant. That is definitely an error.
4159 raise Program_Error
;
4167 function Expr_Value_S
(N
: Node_Id
) return Node_Id
is
4169 if Nkind
(N
) = N_String_Literal
then
4172 pragma Assert
(Ekind
(Entity
(N
)) = E_Constant
);
4173 return Expr_Value_S
(Constant_Value
(Entity
(N
)));
4177 ----------------------------------
4178 -- Find_Universal_Operator_Type --
4179 ----------------------------------
4181 function Find_Universal_Operator_Type
(N
: Node_Id
) return Entity_Id
is
4182 PN
: constant Node_Id
:= Parent
(N
);
4183 Call
: constant Node_Id
:= Original_Node
(N
);
4184 Is_Int
: constant Boolean := Is_Integer_Type
(Etype
(N
));
4186 Is_Fix
: constant Boolean :=
4187 Nkind
(N
) in N_Binary_Op
4188 and then Nkind
(Right_Opnd
(N
)) /= Nkind
(Left_Opnd
(N
));
4189 -- A mixed-mode operation in this context indicates the presence of
4190 -- fixed-point type in the designated package.
4192 Is_Relational
: constant Boolean := Etype
(N
) = Standard_Boolean
;
4193 -- Case where N is a relational (or membership) operator (else it is an
4196 In_Membership
: constant Boolean :=
4197 Nkind
(PN
) in N_Membership_Test
4199 Nkind
(Right_Opnd
(PN
)) = N_Range
4201 Is_Universal_Numeric_Type
(Etype
(Left_Opnd
(PN
)))
4203 Is_Universal_Numeric_Type
4204 (Etype
(Low_Bound
(Right_Opnd
(PN
))))
4206 Is_Universal_Numeric_Type
4207 (Etype
(High_Bound
(Right_Opnd
(PN
))));
4208 -- Case where N is part of a membership test with a universal range
4212 Typ1
: Entity_Id
:= Empty
;
4215 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean;
4216 -- Check whether one operand is a mixed-mode operation that requires the
4217 -- presence of a fixed-point type. Given that all operands are universal
4218 -- and have been constant-folded, retrieve the original function call.
4220 ---------------------------
4221 -- Is_Mixed_Mode_Operand --
4222 ---------------------------
4224 function Is_Mixed_Mode_Operand
(Op
: Node_Id
) return Boolean is
4225 Onod
: constant Node_Id
:= Original_Node
(Op
);
4227 return Nkind
(Onod
) = N_Function_Call
4228 and then Present
(Next_Actual
(First_Actual
(Onod
)))
4229 and then Etype
(First_Actual
(Onod
)) /=
4230 Etype
(Next_Actual
(First_Actual
(Onod
)));
4231 end Is_Mixed_Mode_Operand
;
4233 -- Start of processing for Find_Universal_Operator_Type
4236 if Nkind
(Call
) /= N_Function_Call
4237 or else Nkind
(Name
(Call
)) /= N_Expanded_Name
4241 -- There are several cases where the context does not imply the type of
4243 -- - the universal expression appears in a type conversion;
4244 -- - the expression is a relational operator applied to universal
4246 -- - the expression is a membership test with a universal operand
4247 -- and a range with universal bounds.
4249 elsif Nkind
(Parent
(N
)) = N_Type_Conversion
4250 or else Is_Relational
4251 or else In_Membership
4253 Pack
:= Entity
(Prefix
(Name
(Call
)));
4255 -- If the prefix is a package declared elsewhere, iterate over its
4256 -- visible entities, otherwise iterate over all declarations in the
4257 -- designated scope.
4259 if Ekind
(Pack
) = E_Package
4260 and then not In_Open_Scopes
(Pack
)
4262 Priv_E
:= First_Private_Entity
(Pack
);
4268 E
:= First_Entity
(Pack
);
4269 while Present
(E
) and then E
/= Priv_E
loop
4270 if Is_Numeric_Type
(E
)
4271 and then Nkind
(Parent
(E
)) /= N_Subtype_Declaration
4272 and then Comes_From_Source
(E
)
4273 and then Is_Integer_Type
(E
) = Is_Int
4274 and then (Nkind
(N
) in N_Unary_Op
4275 or else Is_Relational
4276 or else Is_Fixed_Point_Type
(E
) = Is_Fix
)
4281 -- Before emitting an error, check for the presence of a
4282 -- mixed-mode operation that specifies a fixed point type.
4286 (Is_Mixed_Mode_Operand
(Left_Opnd
(N
))
4287 or else Is_Mixed_Mode_Operand
(Right_Opnd
(N
)))
4288 and then Is_Fixed_Point_Type
(E
) /= Is_Fixed_Point_Type
(Typ1
)
4291 if Is_Fixed_Point_Type
(E
) then
4296 -- More than one type of the proper class declared in P
4298 Error_Msg_N
("ambiguous operation", N
);
4299 Error_Msg_Sloc
:= Sloc
(Typ1
);
4300 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4301 Error_Msg_Sloc
:= Sloc
(E
);
4302 Error_Msg_N
("\possible interpretation (inherited)#", N
);
4312 end Find_Universal_Operator_Type
;
4314 --------------------------
4315 -- Flag_Non_Static_Expr --
4316 --------------------------
4318 procedure Flag_Non_Static_Expr
(Msg
: String; Expr
: Node_Id
) is
4320 if Error_Posted
(Expr
) and then not All_Errors_Mode
then
4323 Error_Msg_F
(Msg
, Expr
);
4324 Why_Not_Static
(Expr
);
4326 end Flag_Non_Static_Expr
;
4332 procedure Fold_Str
(N
: Node_Id
; Val
: String_Id
; Static
: Boolean) is
4333 Loc
: constant Source_Ptr
:= Sloc
(N
);
4334 Typ
: constant Entity_Id
:= Etype
(N
);
4337 if Raises_Constraint_Error
(N
) then
4338 Set_Is_Static_Expression
(N
, Static
);
4342 Rewrite
(N
, Make_String_Literal
(Loc
, Strval
=> Val
));
4344 -- We now have the literal with the right value, both the actual type
4345 -- and the expected type of this literal are taken from the expression
4346 -- that was evaluated. So now we do the Analyze and Resolve.
4348 -- Note that we have to reset Is_Static_Expression both after the
4349 -- analyze step (because Resolve will evaluate the literal, which
4350 -- will cause semantic errors if it is marked as static), and after
4351 -- the Resolve step (since Resolve in some cases resets this flag).
4354 Set_Is_Static_Expression
(N
, Static
);
4357 Set_Is_Static_Expression
(N
, Static
);
4364 procedure Fold_Uint
(N
: Node_Id
; Val
: Uint
; Static
: Boolean) is
4365 Loc
: constant Source_Ptr
:= Sloc
(N
);
4366 Typ
: Entity_Id
:= Etype
(N
);
4370 if Raises_Constraint_Error
(N
) then
4371 Set_Is_Static_Expression
(N
, Static
);
4375 -- If we are folding a named number, retain the entity in the literal,
4378 if Is_Entity_Name
(N
) and then Ekind
(Entity
(N
)) = E_Named_Integer
then
4384 if Is_Private_Type
(Typ
) then
4385 Typ
:= Full_View
(Typ
);
4388 -- For a result of type integer, substitute an N_Integer_Literal node
4389 -- for the result of the compile time evaluation of the expression.
4390 -- For ASIS use, set a link to the original named number when not in
4391 -- a generic context.
4393 if Is_Integer_Type
(Typ
) then
4394 Rewrite
(N
, Make_Integer_Literal
(Loc
, Val
));
4395 Set_Original_Entity
(N
, Ent
);
4397 -- Otherwise we have an enumeration type, and we substitute either
4398 -- an N_Identifier or N_Character_Literal to represent the enumeration
4399 -- literal corresponding to the given value, which must always be in
4400 -- range, because appropriate tests have already been made for this.
4402 else pragma Assert
(Is_Enumeration_Type
(Typ
));
4403 Rewrite
(N
, Get_Enum_Lit_From_Pos
(Etype
(N
), Val
, Loc
));
4406 -- We now have the literal with the right value, both the actual type
4407 -- and the expected type of this literal are taken from the expression
4408 -- that was evaluated. So now we do the Analyze and Resolve.
4410 -- Note that we have to reset Is_Static_Expression both after the
4411 -- analyze step (because Resolve will evaluate the literal, which
4412 -- will cause semantic errors if it is marked as static), and after
4413 -- the Resolve step (since Resolve in some cases sets this flag).
4416 Set_Is_Static_Expression
(N
, Static
);
4419 Set_Is_Static_Expression
(N
, Static
);
4426 procedure Fold_Ureal
(N
: Node_Id
; Val
: Ureal
; Static
: Boolean) is
4427 Loc
: constant Source_Ptr
:= Sloc
(N
);
4428 Typ
: constant Entity_Id
:= Etype
(N
);
4432 if Raises_Constraint_Error
(N
) then
4433 Set_Is_Static_Expression
(N
, Static
);
4437 -- If we are folding a named number, retain the entity in the literal,
4440 if Is_Entity_Name
(N
) and then Ekind
(Entity
(N
)) = E_Named_Real
then
4446 Rewrite
(N
, Make_Real_Literal
(Loc
, Realval
=> Val
));
4448 -- Set link to original named number, for ASIS use
4450 Set_Original_Entity
(N
, Ent
);
4452 -- We now have the literal with the right value, both the actual type
4453 -- and the expected type of this literal are taken from the expression
4454 -- that was evaluated. So now we do the Analyze and Resolve.
4456 -- Note that we have to reset Is_Static_Expression both after the
4457 -- analyze step (because Resolve will evaluate the literal, which
4458 -- will cause semantic errors if it is marked as static), and after
4459 -- the Resolve step (since Resolve in some cases sets this flag).
4462 Set_Is_Static_Expression
(N
, Static
);
4465 Set_Is_Static_Expression
(N
, Static
);
4472 function From_Bits
(B
: Bits
; T
: Entity_Id
) return Uint
is
4476 for J
in 0 .. B
'Last loop
4482 if Non_Binary_Modulus
(T
) then
4483 V
:= V
mod Modulus
(T
);
4489 --------------------
4490 -- Get_String_Val --
4491 --------------------
4493 function Get_String_Val
(N
: Node_Id
) return Node_Id
is
4495 if Nkind_In
(N
, N_String_Literal
, N_Character_Literal
) then
4498 pragma Assert
(Is_Entity_Name
(N
));
4499 return Get_String_Val
(Constant_Value
(Entity
(N
)));
4507 procedure Initialize
is
4509 CV_Cache
:= (others => (Node_High_Bound
, Uint_0
));
4512 --------------------
4513 -- In_Subrange_Of --
4514 --------------------
4516 function In_Subrange_Of
4519 Fixed_Int
: Boolean := False) return Boolean
4528 if T1
= T2
or else Is_Subtype_Of
(T1
, T2
) then
4531 -- Never in range if both types are not scalar. Don't know if this can
4532 -- actually happen, but just in case.
4534 elsif not Is_Scalar_Type
(T1
) or else not Is_Scalar_Type
(T2
) then
4537 -- If T1 has infinities but T2 doesn't have infinities, then T1 is
4538 -- definitely not compatible with T2.
4540 elsif Is_Floating_Point_Type
(T1
)
4541 and then Has_Infinities
(T1
)
4542 and then Is_Floating_Point_Type
(T2
)
4543 and then not Has_Infinities
(T2
)
4548 L1
:= Type_Low_Bound
(T1
);
4549 H1
:= Type_High_Bound
(T1
);
4551 L2
:= Type_Low_Bound
(T2
);
4552 H2
:= Type_High_Bound
(T2
);
4554 -- Check bounds to see if comparison possible at compile time
4556 if Compile_Time_Compare
(L1
, L2
, Assume_Valid
=> True) in Compare_GE
4558 Compile_Time_Compare
(H1
, H2
, Assume_Valid
=> True) in Compare_LE
4563 -- If bounds not comparable at compile time, then the bounds of T2
4564 -- must be compile time known or we cannot answer the query.
4566 if not Compile_Time_Known_Value
(L2
)
4567 or else not Compile_Time_Known_Value
(H2
)
4572 -- If the bounds of T1 are know at compile time then use these
4573 -- ones, otherwise use the bounds of the base type (which are of
4574 -- course always static).
4576 if not Compile_Time_Known_Value
(L1
) then
4577 L1
:= Type_Low_Bound
(Base_Type
(T1
));
4580 if not Compile_Time_Known_Value
(H1
) then
4581 H1
:= Type_High_Bound
(Base_Type
(T1
));
4584 -- Fixed point types should be considered as such only if
4585 -- flag Fixed_Int is set to False.
4587 if Is_Floating_Point_Type
(T1
) or else Is_Floating_Point_Type
(T2
)
4588 or else (Is_Fixed_Point_Type
(T1
) and then not Fixed_Int
)
4589 or else (Is_Fixed_Point_Type
(T2
) and then not Fixed_Int
)
4592 Expr_Value_R
(L2
) <= Expr_Value_R
(L1
)
4594 Expr_Value_R
(H2
) >= Expr_Value_R
(H1
);
4598 Expr_Value
(L2
) <= Expr_Value
(L1
)
4600 Expr_Value
(H2
) >= Expr_Value
(H1
);
4605 -- If any exception occurs, it means that we have some bug in the compiler
4606 -- possibly triggered by a previous error, or by some unforeseen peculiar
4607 -- occurrence. However, this is only an optimization attempt, so there is
4608 -- really no point in crashing the compiler. Instead we just decide, too
4609 -- bad, we can't figure out the answer in this case after all.
4614 -- Debug flag K disables this behavior (useful for debugging)
4616 if Debug_Flag_K
then
4627 function Is_In_Range
4630 Assume_Valid
: Boolean := False;
4631 Fixed_Int
: Boolean := False;
4632 Int_Real
: Boolean := False) return Boolean
4636 Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
) = In_Range
;
4643 function Is_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
4644 Typ
: constant Entity_Id
:= Etype
(Lo
);
4647 if not Compile_Time_Known_Value
(Lo
)
4648 or else not Compile_Time_Known_Value
(Hi
)
4653 if Is_Discrete_Type
(Typ
) then
4654 return Expr_Value
(Lo
) > Expr_Value
(Hi
);
4655 else pragma Assert
(Is_Real_Type
(Typ
));
4656 return Expr_Value_R
(Lo
) > Expr_Value_R
(Hi
);
4660 -------------------------
4661 -- Is_OK_Static_Choice --
4662 -------------------------
4664 function Is_OK_Static_Choice
(Choice
: Node_Id
) return Boolean is
4666 -- Check various possibilities for choice
4668 -- Note: for membership tests, we test more cases than are possible
4669 -- (in particular subtype indication), but it doesn't matter because
4670 -- it just won't occur (we have already done a syntax check).
4672 if Nkind
(Choice
) = N_Others_Choice
then
4675 elsif Nkind
(Choice
) = N_Range
then
4676 return Is_OK_Static_Range
(Choice
);
4678 elsif Nkind
(Choice
) = N_Subtype_Indication
4680 (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
4682 return Is_OK_Static_Subtype
(Etype
(Choice
));
4685 return Is_OK_Static_Expression
(Choice
);
4687 end Is_OK_Static_Choice
;
4689 ------------------------------
4690 -- Is_OK_Static_Choice_List --
4691 ------------------------------
4693 function Is_OK_Static_Choice_List
(Choices
: List_Id
) return Boolean is
4697 if not Is_Static_Choice_List
(Choices
) then
4701 Choice
:= First
(Choices
);
4702 while Present
(Choice
) loop
4703 if not Is_OK_Static_Choice
(Choice
) then
4704 Set_Raises_Constraint_Error
(Choice
);
4712 end Is_OK_Static_Choice_List
;
4714 -----------------------------
4715 -- Is_OK_Static_Expression --
4716 -----------------------------
4718 function Is_OK_Static_Expression
(N
: Node_Id
) return Boolean is
4720 return Is_Static_Expression
(N
) and then not Raises_Constraint_Error
(N
);
4721 end Is_OK_Static_Expression
;
4723 ------------------------
4724 -- Is_OK_Static_Range --
4725 ------------------------
4727 -- A static range is a range whose bounds are static expressions, or a
4728 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4729 -- We have already converted range attribute references, so we get the
4730 -- "or" part of this rule without needing a special test.
4732 function Is_OK_Static_Range
(N
: Node_Id
) return Boolean is
4734 return Is_OK_Static_Expression
(Low_Bound
(N
))
4735 and then Is_OK_Static_Expression
(High_Bound
(N
));
4736 end Is_OK_Static_Range
;
4738 --------------------------
4739 -- Is_OK_Static_Subtype --
4740 --------------------------
4742 -- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
4743 -- neither bound raises constraint error when evaluated.
4745 function Is_OK_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
4746 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
4747 Anc_Subt
: Entity_Id
;
4750 -- First a quick check on the non static subtype flag. As described
4751 -- in further detail in Einfo, this flag is not decisive in all cases,
4752 -- but if it is set, then the subtype is definitely non-static.
4754 if Is_Non_Static_Subtype
(Typ
) then
4758 Anc_Subt
:= Ancestor_Subtype
(Typ
);
4760 if Anc_Subt
= Empty
then
4764 if Is_Generic_Type
(Root_Type
(Base_T
))
4765 or else Is_Generic_Actual_Type
(Base_T
)
4771 elsif Is_String_Type
(Typ
) then
4773 Ekind
(Typ
) = E_String_Literal_Subtype
4775 (Is_OK_Static_Subtype
(Component_Type
(Typ
))
4776 and then Is_OK_Static_Subtype
(Etype
(First_Index
(Typ
))));
4780 elsif Is_Scalar_Type
(Typ
) then
4781 if Base_T
= Typ
then
4785 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
4786 -- Get_Type_{Low,High}_Bound.
4788 return Is_OK_Static_Subtype
(Anc_Subt
)
4789 and then Is_OK_Static_Expression
(Type_Low_Bound
(Typ
))
4790 and then Is_OK_Static_Expression
(Type_High_Bound
(Typ
));
4793 -- Types other than string and scalar types are never static
4798 end Is_OK_Static_Subtype
;
4800 ---------------------
4801 -- Is_Out_Of_Range --
4802 ---------------------
4804 function Is_Out_Of_Range
4807 Assume_Valid
: Boolean := False;
4808 Fixed_Int
: Boolean := False;
4809 Int_Real
: Boolean := False) return Boolean
4812 return Test_In_Range
(N
, Typ
, Assume_Valid
, Fixed_Int
, Int_Real
) =
4814 end Is_Out_Of_Range
;
4816 ----------------------
4817 -- Is_Static_Choice --
4818 ----------------------
4820 function Is_Static_Choice
(Choice
: Node_Id
) return Boolean is
4822 -- Check various possibilities for choice
4824 -- Note: for membership tests, we test more cases than are possible
4825 -- (in particular subtype indication), but it doesn't matter because
4826 -- it just won't occur (we have already done a syntax check).
4828 if Nkind
(Choice
) = N_Others_Choice
then
4831 elsif Nkind
(Choice
) = N_Range
then
4832 return Is_Static_Range
(Choice
);
4834 elsif Nkind
(Choice
) = N_Subtype_Indication
4836 (Is_Entity_Name
(Choice
) and then Is_Type
(Entity
(Choice
)))
4838 return Is_Static_Subtype
(Etype
(Choice
));
4841 return Is_Static_Expression
(Choice
);
4843 end Is_Static_Choice
;
4845 ---------------------------
4846 -- Is_Static_Choice_List --
4847 ---------------------------
4849 function Is_Static_Choice_List
(Choices
: List_Id
) return Boolean is
4853 Choice
:= First
(Choices
);
4854 while Present
(Choice
) loop
4855 if not Is_Static_Choice
(Choice
) then
4863 end Is_Static_Choice_List
;
4865 ---------------------
4866 -- Is_Static_Range --
4867 ---------------------
4869 -- A static range is a range whose bounds are static expressions, or a
4870 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
4871 -- We have already converted range attribute references, so we get the
4872 -- "or" part of this rule without needing a special test.
4874 function Is_Static_Range
(N
: Node_Id
) return Boolean is
4876 return Is_Static_Expression
(Low_Bound
(N
))
4878 Is_Static_Expression
(High_Bound
(N
));
4879 end Is_Static_Range
;
4881 -----------------------
4882 -- Is_Static_Subtype --
4883 -----------------------
4885 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
4887 function Is_Static_Subtype
(Typ
: Entity_Id
) return Boolean is
4888 Base_T
: constant Entity_Id
:= Base_Type
(Typ
);
4889 Anc_Subt
: Entity_Id
;
4892 -- First a quick check on the non static subtype flag. As described
4893 -- in further detail in Einfo, this flag is not decisive in all cases,
4894 -- but if it is set, then the subtype is definitely non-static.
4896 if Is_Non_Static_Subtype
(Typ
) then
4900 Anc_Subt
:= Ancestor_Subtype
(Typ
);
4902 if Anc_Subt
= Empty
then
4906 if Is_Generic_Type
(Root_Type
(Base_T
))
4907 or else Is_Generic_Actual_Type
(Base_T
)
4913 elsif Is_String_Type
(Typ
) then
4915 Ekind
(Typ
) = E_String_Literal_Subtype
4916 or else (Is_Static_Subtype
(Component_Type
(Typ
))
4917 and then Is_Static_Subtype
(Etype
(First_Index
(Typ
))));
4921 elsif Is_Scalar_Type
(Typ
) then
4922 if Base_T
= Typ
then
4926 return Is_Static_Subtype
(Anc_Subt
)
4927 and then Is_Static_Expression
(Type_Low_Bound
(Typ
))
4928 and then Is_Static_Expression
(Type_High_Bound
(Typ
));
4931 -- Types other than string and scalar types are never static
4936 end Is_Static_Subtype
;
4938 -------------------------------
4939 -- Is_Statically_Unevaluated --
4940 -------------------------------
4942 function Is_Statically_Unevaluated
(Expr
: Node_Id
) return Boolean is
4943 function Check_Case_Expr_Alternative
4944 (CEA
: Node_Id
) return Match_Result
;
4945 -- We have a message emanating from the Expression of a case expression
4946 -- alternative. We examine this alternative, as follows:
4948 -- If the selecting expression of the parent case is non-static, or
4949 -- if any of the discrete choices of the given case alternative are
4950 -- non-static or raise Constraint_Error, return Non_Static.
4952 -- Otherwise check if the selecting expression matches any of the given
4953 -- discrete choices. If so, the alternative is executed and we return
4954 -- Match, otherwise, the alternative can never be executed, and so we
4957 ---------------------------------
4958 -- Check_Case_Expr_Alternative --
4959 ---------------------------------
4961 function Check_Case_Expr_Alternative
4962 (CEA
: Node_Id
) return Match_Result
4964 Case_Exp
: constant Node_Id
:= Parent
(CEA
);
4969 pragma Assert
(Nkind
(Case_Exp
) = N_Case_Expression
);
4971 -- Check that selecting expression is static
4973 if not Is_OK_Static_Expression
(Expression
(Case_Exp
)) then
4977 if not Is_OK_Static_Choice_List
(Discrete_Choices
(CEA
)) then
4981 -- All choices are now known to be static. Now see if alternative
4982 -- matches one of the choices.
4984 Choice
:= First
(Discrete_Choices
(CEA
));
4985 while Present
(Choice
) loop
4987 -- Check various possibilities for choice, returning Match if we
4988 -- find the selecting value matches any of the choices. Note that
4989 -- we know we are the last choice, so we don't have to keep going.
4991 if Nkind
(Choice
) = N_Others_Choice
then
4993 -- Others choice is a bit annoying, it matches if none of the
4994 -- previous alternatives matches (note that we know we are the
4995 -- last alternative in this case, so we can just go backwards
4996 -- from us to see if any previous one matches).
4998 Prev_CEA
:= Prev
(CEA
);
4999 while Present
(Prev_CEA
) loop
5000 if Check_Case_Expr_Alternative
(Prev_CEA
) = Match
then
5009 -- Else we have a normal static choice
5011 elsif Choice_Matches
(Expression
(Case_Exp
), Choice
) = Match
then
5015 -- If we fall through, it means that the discrete choice did not
5016 -- match the selecting expression, so continue.
5021 -- If we get through that loop then all choices were static, and none
5022 -- of them matched the selecting expression. So return No_Match.
5025 end Check_Case_Expr_Alternative
;
5033 -- Start of processing for Is_Statically_Unevaluated
5036 -- The (32.x) references here are from RM section 4.9
5038 -- (32.1) An expression is statically unevaluated if it is part of ...
5040 -- This means we have to climb the tree looking for one of the cases
5047 -- (32.2) The right operand of a static short-circuit control form
5048 -- whose value is determined by its left operand.
5050 -- AND THEN with False as left operand
5052 if Nkind
(P
) = N_And_Then
5053 and then Compile_Time_Known_Value
(Left_Opnd
(P
))
5054 and then Is_False
(Expr_Value
(Left_Opnd
(P
)))
5058 -- OR ELSE with True as left operand
5060 elsif Nkind
(P
) = N_Or_Else
5061 and then Compile_Time_Known_Value
(Left_Opnd
(P
))
5062 and then Is_True
(Expr_Value
(Left_Opnd
(P
)))
5066 -- (32.3) A dependent_expression of an if_expression whose associated
5067 -- condition is static and equals False.
5069 elsif Nkind
(P
) = N_If_Expression
then
5071 Cond
: constant Node_Id
:= First
(Expressions
(P
));
5072 Texp
: constant Node_Id
:= Next
(Cond
);
5073 Fexp
: constant Node_Id
:= Next
(Texp
);
5076 if Compile_Time_Known_Value
(Cond
) then
5078 -- Condition is True and we are in the right operand
5080 if Is_True
(Expr_Value
(Cond
)) and then OldP
= Fexp
then
5083 -- Condition is False and we are in the left operand
5085 elsif Is_False
(Expr_Value
(Cond
)) and then OldP
= Texp
then
5091 -- (32.4) A condition or dependent_expression of an if_expression
5092 -- where the condition corresponding to at least one preceding
5093 -- dependent_expression of the if_expression is static and equals
5096 -- This refers to cases like
5098 -- (if True then 1 elsif 1/0=2 then 2 else 3)
5100 -- But we expand elsif's out anyway, so the above looks like:
5102 -- (if True then 1 else (if 1/0=2 then 2 else 3))
5104 -- So for us this is caught by the above check for the 32.3 case.
5106 -- (32.5) A dependent_expression of a case_expression whose
5107 -- selecting_expression is static and whose value is not covered
5108 -- by the corresponding discrete_choice_list.
5110 elsif Nkind
(P
) = N_Case_Expression_Alternative
then
5112 -- First, we have to be in the expression to suppress messages.
5113 -- If we are within one of the choices, we want the message.
5115 if OldP
= Expression
(P
) then
5117 -- Statically unevaluated if alternative does not match
5119 if Check_Case_Expr_Alternative
(P
) = No_Match
then
5124 -- (32.6) A choice_expression (or a simple_expression of a range
5125 -- that occurs as a membership_choice of a membership_choice_list)
5126 -- of a static membership test that is preceded in the enclosing
5127 -- membership_choice_list by another item whose individual
5128 -- membership test (see (RM 4.5.2)) statically yields True.
5130 elsif Nkind
(P
) in N_Membership_Test
then
5132 -- Only possibly unevaluated if simple expression is static
5134 if not Is_OK_Static_Expression
(Left_Opnd
(P
)) then
5137 -- All members of the choice list must be static
5139 elsif (Present
(Right_Opnd
(P
))
5140 and then not Is_OK_Static_Choice
(Right_Opnd
(P
)))
5141 or else (Present
(Alternatives
(P
))
5143 not Is_OK_Static_Choice_List
(Alternatives
(P
)))
5147 -- If expression is the one and only alternative, then it is
5148 -- definitely not statically unevaluated, so we only have to
5149 -- test the case where there are alternatives present.
5151 elsif Present
(Alternatives
(P
)) then
5153 -- Look for previous matching Choice
5155 Choice
:= First
(Alternatives
(P
));
5156 while Present
(Choice
) loop
5158 -- If we reached us and no previous choices matched, this
5159 -- is not the case where we are statically unevaluated.
5161 exit when OldP
= Choice
;
5163 -- If a previous choice matches, then that is the case where
5164 -- we know our choice is statically unevaluated.
5166 if Choice_Matches
(Left_Opnd
(P
), Choice
) = Match
then
5173 -- If we fall through the loop, we were not one of the choices,
5174 -- we must have been the expression, so that is not covered by
5175 -- this rule, and we keep going.
5181 -- OK, not statically unevaluated at this level, see if we should
5182 -- keep climbing to look for a higher level reason.
5184 -- Special case for component association in aggregates, where
5185 -- we want to keep climbing up to the parent aggregate.
5187 if Nkind
(P
) = N_Component_Association
5188 and then Nkind
(Parent
(P
)) = N_Aggregate
5192 -- All done if not still within subexpression
5195 exit when Nkind
(P
) not in N_Subexpr
;
5199 -- If we fall through the loop, not one of the cases covered!
5202 end Is_Statically_Unevaluated
;
5204 --------------------
5205 -- Not_Null_Range --
5206 --------------------
5208 function Not_Null_Range
(Lo
: Node_Id
; Hi
: Node_Id
) return Boolean is
5209 Typ
: constant Entity_Id
:= Etype
(Lo
);
5212 if not Compile_Time_Known_Value
(Lo
)
5213 or else not Compile_Time_Known_Value
(Hi
)
5218 if Is_Discrete_Type
(Typ
) then
5219 return Expr_Value
(Lo
) <= Expr_Value
(Hi
);
5220 else pragma Assert
(Is_Real_Type
(Typ
));
5221 return Expr_Value_R
(Lo
) <= Expr_Value_R
(Hi
);
5229 function OK_Bits
(N
: Node_Id
; Bits
: Uint
) return Boolean is
5231 -- We allow a maximum of 500,000 bits which seems a reasonable limit
5233 if Bits
< 500_000
then
5236 -- Error if this maximum is exceeded
5239 Error_Msg_N
("static value too large, capacity exceeded", N
);
5248 procedure Out_Of_Range
(N
: Node_Id
) is
5250 -- If we have the static expression case, then this is an illegality
5251 -- in Ada 95 mode, except that in an instance, we never generate an
5252 -- error (if the error is legitimate, it was already diagnosed in the
5255 if Is_Static_Expression
(N
)
5256 and then not In_Instance
5257 and then not In_Inlined_Body
5258 and then Ada_Version
>= Ada_95
5260 -- No message if we are statically unevaluated
5262 if Is_Statically_Unevaluated
(N
) then
5265 -- The expression to compute the length of a packed array is attached
5266 -- to the array type itself, and deserves a separate message.
5268 elsif Nkind
(Parent
(N
)) = N_Defining_Identifier
5269 and then Is_Array_Type
(Parent
(N
))
5270 and then Present
(Packed_Array_Impl_Type
(Parent
(N
)))
5271 and then Present
(First_Rep_Item
(Parent
(N
)))
5274 ("length of packed array must not exceed Integer''Last",
5275 First_Rep_Item
(Parent
(N
)));
5276 Rewrite
(N
, Make_Integer_Literal
(Sloc
(N
), Uint_1
));
5278 -- All cases except the special array case
5281 Apply_Compile_Time_Constraint_Error
5282 (N
, "value not in range of}", CE_Range_Check_Failed
);
5285 -- Here we generate a warning for the Ada 83 case, or when we are in an
5286 -- instance, or when we have a non-static expression case.
5289 Apply_Compile_Time_Constraint_Error
5290 (N
, "value not in range of}??", CE_Range_Check_Failed
);
5294 ----------------------
5295 -- Predicates_Match --
5296 ----------------------
5298 function Predicates_Match
(T1
, T2
: Entity_Id
) return Boolean is
5303 if Ada_Version
< Ada_2012
then
5306 -- Both types must have predicates or lack them
5308 elsif Has_Predicates
(T1
) /= Has_Predicates
(T2
) then
5311 -- Check matching predicates
5316 (T1
, Name_Static_Predicate
, Check_Parents
=> False);
5319 (T2
, Name_Static_Predicate
, Check_Parents
=> False);
5321 -- Subtypes statically match if the predicate comes from the
5322 -- same declaration, which can only happen if one is a subtype
5323 -- of the other and has no explicit predicate.
5325 -- Suppress warnings on order of actuals, which is otherwise
5326 -- triggered by one of the two calls below.
5328 pragma Warnings
(Off
);
5329 return Pred1
= Pred2
5330 or else (No
(Pred1
) and then Is_Subtype_Of
(T1
, T2
))
5331 or else (No
(Pred2
) and then Is_Subtype_Of
(T2
, T1
));
5332 pragma Warnings
(On
);
5334 end Predicates_Match
;
5336 ---------------------------------------------
5337 -- Real_Or_String_Static_Predicate_Matches --
5338 ---------------------------------------------
5340 function Real_Or_String_Static_Predicate_Matches
5342 Typ
: Entity_Id
) return Boolean
5344 Expr
: constant Node_Id
:= Static_Real_Or_String_Predicate
(Typ
);
5345 -- The predicate expression from the type
5347 Pfun
: constant Entity_Id
:= Predicate_Function
(Typ
);
5348 -- The entity for the predicate function
5350 Ent_Name
: constant Name_Id
:= Chars
(First_Formal
(Pfun
));
5351 -- The name of the formal of the predicate function. Occurrences of the
5352 -- type name in Expr have been rewritten as references to this formal,
5353 -- and it has a unique name, so we can identify references by this name.
5356 -- Copy of the predicate function tree
5358 function Process
(N
: Node_Id
) return Traverse_Result
;
5359 -- Function used to process nodes during the traversal in which we will
5360 -- find occurrences of the entity name, and replace such occurrences
5361 -- by a real literal with the value to be tested.
5363 procedure Traverse
is new Traverse_Proc
(Process
);
5364 -- The actual traversal procedure
5370 function Process
(N
: Node_Id
) return Traverse_Result
is
5372 if Nkind
(N
) = N_Identifier
and then Chars
(N
) = Ent_Name
then
5374 Nod
: constant Node_Id
:= New_Copy
(Val
);
5376 Set_Sloc
(Nod
, Sloc
(N
));
5386 -- Start of processing for Real_Or_String_Static_Predicate_Matches
5389 -- First deal with special case of inherited predicate, where the
5390 -- predicate expression looks like:
5392 -- Expr and then xxPredicate (typ (Ent))
5394 -- where Expr is the predicate expression for this level, and the
5395 -- right operand is the call to evaluate the inherited predicate.
5397 if Nkind
(Expr
) = N_And_Then
5398 and then Nkind
(Right_Opnd
(Expr
)) = N_Function_Call
5400 -- OK we have the inherited case, so make a call to evaluate the
5401 -- inherited predicate. If that fails, so do we!
5404 Real_Or_String_Static_Predicate_Matches
5406 Typ
=> Etype
(First_Formal
(Entity
(Name
(Right_Opnd
(Expr
))))))
5411 -- Use the left operand for the continued processing
5413 Copy
:= Copy_Separate_Tree
(Left_Opnd
(Expr
));
5415 -- Case where call to predicate function appears on its own
5417 elsif Nkind
(Expr
) = N_Function_Call
then
5419 -- Here the result is just the result of calling the inner predicate
5422 Real_Or_String_Static_Predicate_Matches
5424 Typ
=> Etype
(First_Formal
(Entity
(Name
(Expr
)))));
5426 -- If no inherited predicate, copy whole expression
5429 Copy
:= Copy_Separate_Tree
(Expr
);
5432 -- Now we replace occurrences of the entity by the value
5436 -- And analyze the resulting static expression to see if it is True
5438 Analyze_And_Resolve
(Copy
, Standard_Boolean
);
5439 return Is_True
(Expr_Value
(Copy
));
5440 end Real_Or_String_Static_Predicate_Matches
;
5442 -------------------------
5443 -- Rewrite_In_Raise_CE --
5444 -------------------------
5446 procedure Rewrite_In_Raise_CE
(N
: Node_Id
; Exp
: Node_Id
) is
5447 Typ
: constant Entity_Id
:= Etype
(N
);
5448 Stat
: constant Boolean := Is_Static_Expression
(N
);
5451 -- If we want to raise CE in the condition of a N_Raise_CE node, we
5452 -- can just clear the condition if the reason is appropriate. We do
5453 -- not do this operation if the parent has a reason other than range
5454 -- check failed, because otherwise we would change the reason.
5456 if Present
(Parent
(N
))
5457 and then Nkind
(Parent
(N
)) = N_Raise_Constraint_Error
5458 and then Reason
(Parent
(N
)) =
5459 UI_From_Int
(RT_Exception_Code
'Pos (CE_Range_Check_Failed
))
5461 Set_Condition
(Parent
(N
), Empty
);
5463 -- Else build an explicit N_Raise_CE
5467 Make_Raise_Constraint_Error
(Sloc
(Exp
),
5468 Reason
=> CE_Range_Check_Failed
));
5469 Set_Raises_Constraint_Error
(N
);
5473 -- Set proper flags in result
5475 Set_Raises_Constraint_Error
(N
, True);
5476 Set_Is_Static_Expression
(N
, Stat
);
5477 end Rewrite_In_Raise_CE
;
5479 ---------------------
5480 -- String_Type_Len --
5481 ---------------------
5483 function String_Type_Len
(Stype
: Entity_Id
) return Uint
is
5484 NT
: constant Entity_Id
:= Etype
(First_Index
(Stype
));
5488 if Is_OK_Static_Subtype
(NT
) then
5491 T
:= Base_Type
(NT
);
5494 return Expr_Value
(Type_High_Bound
(T
)) -
5495 Expr_Value
(Type_Low_Bound
(T
)) + 1;
5496 end String_Type_Len
;
5498 ------------------------------------
5499 -- Subtypes_Statically_Compatible --
5500 ------------------------------------
5502 function Subtypes_Statically_Compatible
5505 Formal_Derived_Matching
: Boolean := False) return Boolean
5510 if Is_Scalar_Type
(T1
) then
5512 -- Definitely compatible if we match
5514 if Subtypes_Statically_Match
(T1
, T2
) then
5517 -- If either subtype is nonstatic then they're not compatible
5519 elsif not Is_OK_Static_Subtype
(T1
)
5521 not Is_OK_Static_Subtype
(T2
)
5525 -- If either type has constraint error bounds, then consider that
5526 -- they match to avoid junk cascaded errors here.
5528 elsif not Is_OK_Static_Subtype
(T1
)
5529 or else not Is_OK_Static_Subtype
(T2
)
5533 -- Base types must match, but we don't check that (should we???) but
5534 -- we do at least check that both types are real, or both types are
5537 elsif Is_Real_Type
(T1
) /= Is_Real_Type
(T2
) then
5540 -- Here we check the bounds
5544 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
5545 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
5546 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
5547 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
5550 if Is_Real_Type
(T1
) then
5552 (Expr_Value_R
(LB1
) > Expr_Value_R
(HB1
))
5554 (Expr_Value_R
(LB2
) <= Expr_Value_R
(LB1
)
5556 Expr_Value_R
(HB1
) <= Expr_Value_R
(HB2
));
5560 (Expr_Value
(LB1
) > Expr_Value
(HB1
))
5562 (Expr_Value
(LB2
) <= Expr_Value
(LB1
)
5564 Expr_Value
(HB1
) <= Expr_Value
(HB2
));
5571 elsif Is_Access_Type
(T1
) then
5572 return (not Is_Constrained
(T2
)
5573 or else (Subtypes_Statically_Match
5574 (Designated_Type
(T1
), Designated_Type
(T2
))))
5575 and then not (Can_Never_Be_Null
(T2
)
5576 and then not Can_Never_Be_Null
(T1
));
5581 return (Is_Composite_Type
(T1
) and then not Is_Constrained
(T2
))
5582 or else Subtypes_Statically_Match
(T1
, T2
, Formal_Derived_Matching
);
5584 end Subtypes_Statically_Compatible
;
5586 -------------------------------
5587 -- Subtypes_Statically_Match --
5588 -------------------------------
5590 -- Subtypes statically match if they have statically matching constraints
5591 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
5592 -- they are the same identical constraint, or if they are static and the
5593 -- values match (RM 4.9.1(1)).
5595 -- In addition, in GNAT, the object size (Esize) values of the types must
5596 -- match if they are set (unless checking an actual for a formal derived
5597 -- type). The use of 'Object_Size can cause this to be false even if the
5598 -- types would otherwise match in the RM sense.
5600 function Subtypes_Statically_Match
5603 Formal_Derived_Matching
: Boolean := False) return Boolean
5606 -- A type always statically matches itself
5611 -- No match if sizes different (from use of 'Object_Size). This test
5612 -- is excluded if Formal_Derived_Matching is True, as the base types
5613 -- can be different in that case and typically have different sizes
5614 -- (and Esizes can be set when Frontend_Layout_On_Target is True).
5616 elsif not Formal_Derived_Matching
5617 and then Known_Static_Esize
(T1
)
5618 and then Known_Static_Esize
(T2
)
5619 and then Esize
(T1
) /= Esize
(T2
)
5623 -- No match if predicates do not match
5625 elsif not Predicates_Match
(T1
, T2
) then
5630 elsif Is_Scalar_Type
(T1
) then
5632 -- Base types must be the same
5634 if Base_Type
(T1
) /= Base_Type
(T2
) then
5638 -- A constrained numeric subtype never matches an unconstrained
5639 -- subtype, i.e. both types must be constrained or unconstrained.
5641 -- To understand the requirement for this test, see RM 4.9.1(1).
5642 -- As is made clear in RM 3.5.4(11), type Integer, for example is
5643 -- a constrained subtype with constraint bounds matching the bounds
5644 -- of its corresponding unconstrained base type. In this situation,
5645 -- Integer and Integer'Base do not statically match, even though
5646 -- they have the same bounds.
5648 -- We only apply this test to types in Standard and types that appear
5649 -- in user programs. That way, we do not have to be too careful about
5650 -- setting Is_Constrained right for Itypes.
5652 if Is_Numeric_Type
(T1
)
5653 and then (Is_Constrained
(T1
) /= Is_Constrained
(T2
))
5654 and then (Scope
(T1
) = Standard_Standard
5655 or else Comes_From_Source
(T1
))
5656 and then (Scope
(T2
) = Standard_Standard
5657 or else Comes_From_Source
(T2
))
5661 -- A generic scalar type does not statically match its base type
5662 -- (AI-311). In this case we make sure that the formals, which are
5663 -- first subtypes of their bases, are constrained.
5665 elsif Is_Generic_Type
(T1
)
5666 and then Is_Generic_Type
(T2
)
5667 and then (Is_Constrained
(T1
) /= Is_Constrained
(T2
))
5672 -- If there was an error in either range, then just assume the types
5673 -- statically match to avoid further junk errors.
5675 if No
(Scalar_Range
(T1
)) or else No
(Scalar_Range
(T2
))
5676 or else Error_Posted
(Scalar_Range
(T1
))
5677 or else Error_Posted
(Scalar_Range
(T2
))
5682 -- Otherwise both types have bounds that can be compared
5685 LB1
: constant Node_Id
:= Type_Low_Bound
(T1
);
5686 HB1
: constant Node_Id
:= Type_High_Bound
(T1
);
5687 LB2
: constant Node_Id
:= Type_Low_Bound
(T2
);
5688 HB2
: constant Node_Id
:= Type_High_Bound
(T2
);
5691 -- If the bounds are the same tree node, then match (common case)
5693 if LB1
= LB2
and then HB1
= HB2
then
5696 -- Otherwise bounds must be static and identical value
5699 if not Is_OK_Static_Subtype
(T1
)
5700 or else not Is_OK_Static_Subtype
(T2
)
5704 -- If either type has constraint error bounds, then say that
5705 -- they match to avoid junk cascaded errors here.
5707 elsif not Is_OK_Static_Subtype
(T1
)
5708 or else not Is_OK_Static_Subtype
(T2
)
5712 elsif Is_Real_Type
(T1
) then
5714 (Expr_Value_R
(LB1
) = Expr_Value_R
(LB2
))
5716 (Expr_Value_R
(HB1
) = Expr_Value_R
(HB2
));
5720 Expr_Value
(LB1
) = Expr_Value
(LB2
)
5722 Expr_Value
(HB1
) = Expr_Value
(HB2
);
5727 -- Type with discriminants
5729 elsif Has_Discriminants
(T1
) or else Has_Discriminants
(T2
) then
5731 -- Because of view exchanges in multiple instantiations, conformance
5732 -- checking might try to match a partial view of a type with no
5733 -- discriminants with a full view that has defaulted discriminants.
5734 -- In such a case, use the discriminant constraint of the full view,
5735 -- which must exist because we know that the two subtypes have the
5738 if Has_Discriminants
(T1
) /= Has_Discriminants
(T2
) then
5740 if Is_Private_Type
(T2
)
5741 and then Present
(Full_View
(T2
))
5742 and then Has_Discriminants
(Full_View
(T2
))
5744 return Subtypes_Statically_Match
(T1
, Full_View
(T2
));
5746 elsif Is_Private_Type
(T1
)
5747 and then Present
(Full_View
(T1
))
5748 and then Has_Discriminants
(Full_View
(T1
))
5750 return Subtypes_Statically_Match
(Full_View
(T1
), T2
);
5761 DL1
: constant Elist_Id
:= Discriminant_Constraint
(T1
);
5762 DL2
: constant Elist_Id
:= Discriminant_Constraint
(T2
);
5770 elsif Is_Constrained
(T1
) /= Is_Constrained
(T2
) then
5774 -- Now loop through the discriminant constraints
5776 -- Note: the guard here seems necessary, since it is possible at
5777 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
5779 if Present
(DL1
) and then Present
(DL2
) then
5780 DA1
:= First_Elmt
(DL1
);
5781 DA2
:= First_Elmt
(DL2
);
5782 while Present
(DA1
) loop
5784 Expr1
: constant Node_Id
:= Node
(DA1
);
5785 Expr2
: constant Node_Id
:= Node
(DA2
);
5788 if not Is_OK_Static_Expression
(Expr1
)
5789 or else not Is_OK_Static_Expression
(Expr2
)
5793 -- If either expression raised a constraint error,
5794 -- consider the expressions as matching, since this
5795 -- helps to prevent cascading errors.
5797 elsif Raises_Constraint_Error
(Expr1
)
5798 or else Raises_Constraint_Error
(Expr2
)
5802 elsif Expr_Value
(Expr1
) /= Expr_Value
(Expr2
) then
5815 -- A definite type does not match an indefinite or classwide type.
5816 -- However, a generic type with unknown discriminants may be
5817 -- instantiated with a type with no discriminants, and conformance
5818 -- checking on an inherited operation may compare the actual with the
5819 -- subtype that renames it in the instance.
5821 elsif Has_Unknown_Discriminants
(T1
) /= Has_Unknown_Discriminants
(T2
)
5824 Is_Generic_Actual_Type
(T1
) or else Is_Generic_Actual_Type
(T2
);
5828 elsif Is_Array_Type
(T1
) then
5830 -- If either subtype is unconstrained then both must be, and if both
5831 -- are unconstrained then no further checking is needed.
5833 if not Is_Constrained
(T1
) or else not Is_Constrained
(T2
) then
5834 return not (Is_Constrained
(T1
) or else Is_Constrained
(T2
));
5837 -- Both subtypes are constrained, so check that the index subtypes
5838 -- statically match.
5841 Index1
: Node_Id
:= First_Index
(T1
);
5842 Index2
: Node_Id
:= First_Index
(T2
);
5845 while Present
(Index1
) loop
5847 Subtypes_Statically_Match
(Etype
(Index1
), Etype
(Index2
))
5852 Next_Index
(Index1
);
5853 Next_Index
(Index2
);
5859 elsif Is_Access_Type
(T1
) then
5860 if Can_Never_Be_Null
(T1
) /= Can_Never_Be_Null
(T2
) then
5863 elsif Ekind_In
(T1
, E_Access_Subprogram_Type
,
5864 E_Anonymous_Access_Subprogram_Type
)
5868 (Designated_Type
(T1
),
5869 Designated_Type
(T2
));
5872 Subtypes_Statically_Match
5873 (Designated_Type
(T1
),
5874 Designated_Type
(T2
))
5875 and then Is_Access_Constant
(T1
) = Is_Access_Constant
(T2
);
5878 -- All other types definitely match
5883 end Subtypes_Statically_Match
;
5889 function Test
(Cond
: Boolean) return Uint
is
5898 ---------------------------------
5899 -- Test_Expression_Is_Foldable --
5900 ---------------------------------
5904 procedure Test_Expression_Is_Foldable
5914 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
5918 -- If operand is Any_Type, just propagate to result and do not
5919 -- try to fold, this prevents cascaded errors.
5921 if Etype
(Op1
) = Any_Type
then
5922 Set_Etype
(N
, Any_Type
);
5925 -- If operand raises constraint error, then replace node N with the
5926 -- raise constraint error node, and we are obviously not foldable.
5927 -- Note that this replacement inherits the Is_Static_Expression flag
5928 -- from the operand.
5930 elsif Raises_Constraint_Error
(Op1
) then
5931 Rewrite_In_Raise_CE
(N
, Op1
);
5934 -- If the operand is not static, then the result is not static, and
5935 -- all we have to do is to check the operand since it is now known
5936 -- to appear in a non-static context.
5938 elsif not Is_Static_Expression
(Op1
) then
5939 Check_Non_Static_Context
(Op1
);
5940 Fold
:= Compile_Time_Known_Value
(Op1
);
5943 -- An expression of a formal modular type is not foldable because
5944 -- the modulus is unknown.
5946 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
5947 and then Is_Generic_Type
(Etype
(Op1
))
5949 Check_Non_Static_Context
(Op1
);
5952 -- Here we have the case of an operand whose type is OK, which is
5953 -- static, and which does not raise constraint error, we can fold.
5956 Set_Is_Static_Expression
(N
);
5960 end Test_Expression_Is_Foldable
;
5964 procedure Test_Expression_Is_Foldable
5970 CRT_Safe
: Boolean := False)
5972 Rstat
: constant Boolean := Is_Static_Expression
(Op1
)
5974 Is_Static_Expression
(Op2
);
5980 -- Inhibit folding if -gnatd.f flag set
5982 if Debug_Flag_Dot_F
and then In_Extended_Main_Source_Unit
(N
) then
5986 -- If either operand is Any_Type, just propagate to result and
5987 -- do not try to fold, this prevents cascaded errors.
5989 if Etype
(Op1
) = Any_Type
or else Etype
(Op2
) = Any_Type
then
5990 Set_Etype
(N
, Any_Type
);
5993 -- If left operand raises constraint error, then replace node N with the
5994 -- Raise_Constraint_Error node, and we are obviously not foldable.
5995 -- Is_Static_Expression is set from the two operands in the normal way,
5996 -- and we check the right operand if it is in a non-static context.
5998 elsif Raises_Constraint_Error
(Op1
) then
6000 Check_Non_Static_Context
(Op2
);
6003 Rewrite_In_Raise_CE
(N
, Op1
);
6004 Set_Is_Static_Expression
(N
, Rstat
);
6007 -- Similar processing for the case of the right operand. Note that we
6008 -- don't use this routine for the short-circuit case, so we do not have
6009 -- to worry about that special case here.
6011 elsif Raises_Constraint_Error
(Op2
) then
6013 Check_Non_Static_Context
(Op1
);
6016 Rewrite_In_Raise_CE
(N
, Op2
);
6017 Set_Is_Static_Expression
(N
, Rstat
);
6020 -- Exclude expressions of a generic modular type, as above
6022 elsif Is_Modular_Integer_Type
(Etype
(Op1
))
6023 and then Is_Generic_Type
(Etype
(Op1
))
6025 Check_Non_Static_Context
(Op1
);
6028 -- If result is not static, then check non-static contexts on operands
6029 -- since one of them may be static and the other one may not be static.
6031 elsif not Rstat
then
6032 Check_Non_Static_Context
(Op1
);
6033 Check_Non_Static_Context
(Op2
);
6036 Fold
:= CRT_Safe_Compile_Time_Known_Value
(Op1
)
6037 and then CRT_Safe_Compile_Time_Known_Value
(Op2
);
6039 Fold
:= Compile_Time_Known_Value
(Op1
)
6040 and then Compile_Time_Known_Value
(Op2
);
6045 -- Else result is static and foldable. Both operands are static, and
6046 -- neither raises constraint error, so we can definitely fold.
6049 Set_Is_Static_Expression
(N
);
6054 end Test_Expression_Is_Foldable
;
6060 function Test_In_Range
6063 Assume_Valid
: Boolean;
6064 Fixed_Int
: Boolean;
6065 Int_Real
: Boolean) return Range_Membership
6070 pragma Warnings
(Off
, Assume_Valid
);
6071 -- For now Assume_Valid is unreferenced since the current implementation
6072 -- always returns Unknown if N is not a compile time known value, but we
6073 -- keep the parameter to allow for future enhancements in which we try
6074 -- to get the information in the variable case as well.
6077 -- If an error was posted on expression, then return Unknown, we do not
6078 -- want cascaded errors based on some false analysis of a junk node.
6080 if Error_Posted
(N
) then
6083 -- Expression that raises constraint error is an odd case. We certainly
6084 -- do not want to consider it to be in range. It might make sense to
6085 -- consider it always out of range, but this causes incorrect error
6086 -- messages about static expressions out of range. So we just return
6087 -- Unknown, which is always safe.
6089 elsif Raises_Constraint_Error
(N
) then
6092 -- Universal types have no range limits, so always in range
6094 elsif Typ
= Universal_Integer
or else Typ
= Universal_Real
then
6097 -- Never known if not scalar type. Don't know if this can actually
6098 -- happen, but our spec allows it, so we must check.
6100 elsif not Is_Scalar_Type
(Typ
) then
6103 -- Never known if this is a generic type, since the bounds of generic
6104 -- types are junk. Note that if we only checked for static expressions
6105 -- (instead of compile time known values) below, we would not need this
6106 -- check, because values of a generic type can never be static, but they
6107 -- can be known at compile time.
6109 elsif Is_Generic_Type
(Typ
) then
6112 -- Case of a known compile time value, where we can check if it is in
6113 -- the bounds of the given type.
6115 elsif Compile_Time_Known_Value
(N
) then
6124 Lo
:= Type_Low_Bound
(Typ
);
6125 Hi
:= Type_High_Bound
(Typ
);
6127 LB_Known
:= Compile_Time_Known_Value
(Lo
);
6128 HB_Known
:= Compile_Time_Known_Value
(Hi
);
6130 -- Fixed point types should be considered as such only if flag
6131 -- Fixed_Int is set to False.
6133 if Is_Floating_Point_Type
(Typ
)
6134 or else (Is_Fixed_Point_Type
(Typ
) and then not Fixed_Int
)
6137 Valr
:= Expr_Value_R
(N
);
6139 if LB_Known
and HB_Known
then
6140 if Valr
>= Expr_Value_R
(Lo
)
6142 Valr
<= Expr_Value_R
(Hi
)
6146 return Out_Of_Range
;
6149 elsif (LB_Known
and then Valr
< Expr_Value_R
(Lo
))
6151 (HB_Known
and then Valr
> Expr_Value_R
(Hi
))
6153 return Out_Of_Range
;
6160 Val
:= Expr_Value
(N
);
6162 if LB_Known
and HB_Known
then
6163 if Val
>= Expr_Value
(Lo
) and then Val
<= Expr_Value
(Hi
)
6167 return Out_Of_Range
;
6170 elsif (LB_Known
and then Val
< Expr_Value
(Lo
))
6172 (HB_Known
and then Val
> Expr_Value
(Hi
))
6174 return Out_Of_Range
;
6182 -- Here for value not known at compile time. Case of expression subtype
6183 -- is Typ or is a subtype of Typ, and we can assume expression is valid.
6184 -- In this case we know it is in range without knowing its value.
6187 and then (Etype
(N
) = Typ
or else Is_Subtype_Of
(Etype
(N
), Typ
))
6191 -- Another special case. For signed integer types, if the target type
6192 -- has Is_Known_Valid set, and the source type does not have a larger
6193 -- size, then the source value must be in range. We exclude biased
6194 -- types, because they bizarrely can generate out of range values.
6196 elsif Is_Signed_Integer_Type
(Etype
(N
))
6197 and then Is_Known_Valid
(Typ
)
6198 and then Esize
(Etype
(N
)) <= Esize
(Typ
)
6199 and then not Has_Biased_Representation
(Etype
(N
))
6203 -- For all other cases, result is unknown
6214 procedure To_Bits
(U
: Uint
; B
: out Bits
) is
6216 for J
in 0 .. B
'Last loop
6217 B
(J
) := (U
/ (2 ** J
)) mod 2 /= 0;
6221 --------------------
6222 -- Why_Not_Static --
6223 --------------------
6225 procedure Why_Not_Static
(Expr
: Node_Id
) is
6226 N
: constant Node_Id
:= Original_Node
(Expr
);
6232 procedure Why_Not_Static_List
(L
: List_Id
);
6233 -- A version that can be called on a list of expressions. Finds all
6234 -- non-static violations in any element of the list.
6236 -------------------------
6237 -- Why_Not_Static_List --
6238 -------------------------
6240 procedure Why_Not_Static_List
(L
: List_Id
) is
6243 if Is_Non_Empty_List
(L
) then
6245 while Present
(N
) loop
6250 end Why_Not_Static_List
;
6252 -- Start of processing for Why_Not_Static
6255 -- Ignore call on error or empty node
6257 if No
(Expr
) or else Nkind
(Expr
) = N_Error
then
6261 -- Preprocessing for sub expressions
6263 if Nkind
(Expr
) in N_Subexpr
then
6265 -- Nothing to do if expression is static
6267 if Is_OK_Static_Expression
(Expr
) then
6271 -- Test for constraint error raised
6273 if Raises_Constraint_Error
(Expr
) then
6275 -- Special case membership to find out which piece to flag
6277 if Nkind
(N
) in N_Membership_Test
then
6278 if Raises_Constraint_Error
(Left_Opnd
(N
)) then
6279 Why_Not_Static
(Left_Opnd
(N
));
6282 elsif Present
(Right_Opnd
(N
))
6283 and then Raises_Constraint_Error
(Right_Opnd
(N
))
6285 Why_Not_Static
(Right_Opnd
(N
));
6289 pragma Assert
(Present
(Alternatives
(N
)));
6291 Alt
:= First
(Alternatives
(N
));
6292 while Present
(Alt
) loop
6293 if Raises_Constraint_Error
(Alt
) then
6294 Why_Not_Static
(Alt
);
6302 -- Special case a range to find out which bound to flag
6304 elsif Nkind
(N
) = N_Range
then
6305 if Raises_Constraint_Error
(Low_Bound
(N
)) then
6306 Why_Not_Static
(Low_Bound
(N
));
6309 elsif Raises_Constraint_Error
(High_Bound
(N
)) then
6310 Why_Not_Static
(High_Bound
(N
));
6314 -- Special case attribute to see which part to flag
6316 elsif Nkind
(N
) = N_Attribute_Reference
then
6317 if Raises_Constraint_Error
(Prefix
(N
)) then
6318 Why_Not_Static
(Prefix
(N
));
6322 if Present
(Expressions
(N
)) then
6323 Exp
:= First
(Expressions
(N
));
6324 while Present
(Exp
) loop
6325 if Raises_Constraint_Error
(Exp
) then
6326 Why_Not_Static
(Exp
);
6334 -- Special case a subtype name
6336 elsif Is_Entity_Name
(Expr
) and then Is_Type
(Entity
(Expr
)) then
6338 ("!& is not a static subtype (RM 4.9(26))", N
, Entity
(Expr
));
6342 -- End of special cases
6345 ("!expression raises exception, cannot be static (RM 4.9(34))",
6350 -- If no type, then something is pretty wrong, so ignore
6352 Typ
:= Etype
(Expr
);
6358 -- Type must be scalar or string type (but allow Bignum, since this
6359 -- is really a scalar type from our point of view in this diagnosis).
6361 if not Is_Scalar_Type
(Typ
)
6362 and then not Is_String_Type
(Typ
)
6363 and then not Is_RTE
(Typ
, RE_Bignum
)
6366 ("!static expression must have scalar or string type " &
6372 -- If we got through those checks, test particular node kind
6378 when N_Expanded_Name | N_Identifier | N_Operator_Symbol
=>
6381 if Is_Named_Number
(E
) then
6384 elsif Ekind
(E
) = E_Constant
then
6386 -- One case we can give a metter message is when we have a
6387 -- string literal created by concatenating an aggregate with
6388 -- an others expression.
6390 Entity_Case
: declare
6391 CV
: constant Node_Id
:= Constant_Value
(E
);
6392 CO
: constant Node_Id
:= Original_Node
(CV
);
6394 function Is_Aggregate
(N
: Node_Id
) return Boolean;
6395 -- See if node N came from an others aggregate, if so
6396 -- return True and set Error_Msg_Sloc to aggregate.
6402 function Is_Aggregate
(N
: Node_Id
) return Boolean is
6404 if Nkind
(Original_Node
(N
)) = N_Aggregate
then
6405 Error_Msg_Sloc
:= Sloc
(Original_Node
(N
));
6408 elsif Is_Entity_Name
(N
)
6409 and then Ekind
(Entity
(N
)) = E_Constant
6411 Nkind
(Original_Node
(Constant_Value
(Entity
(N
)))) =
6415 Sloc
(Original_Node
(Constant_Value
(Entity
(N
))));
6423 -- Start of processing for Entity_Case
6426 if Is_Aggregate
(CV
)
6427 or else (Nkind
(CO
) = N_Op_Concat
6428 and then (Is_Aggregate
(Left_Opnd
(CO
))
6430 Is_Aggregate
(Right_Opnd
(CO
))))
6432 Error_Msg_N
("!aggregate (#) is never static", N
);
6434 elsif No
(CV
) or else not Is_Static_Expression
(CV
) then
6436 ("!& is not a static constant (RM 4.9(5))", N
, E
);
6440 elsif Is_Type
(E
) then
6442 ("!& is not a static subtype (RM 4.9(26))", N
, E
);
6446 ("!& is not static constant or named number "
6447 & "(RM 4.9(5))", N
, E
);
6452 when N_Binary_Op | N_Short_Circuit | N_Membership_Test
=>
6453 if Nkind
(N
) in N_Op_Shift
then
6455 ("!shift functions are never static (RM 4.9(6,18))", N
);
6457 Why_Not_Static
(Left_Opnd
(N
));
6458 Why_Not_Static
(Right_Opnd
(N
));
6464 Why_Not_Static
(Right_Opnd
(N
));
6466 -- Attribute reference
6468 when N_Attribute_Reference
=>
6469 Why_Not_Static_List
(Expressions
(N
));
6471 E
:= Etype
(Prefix
(N
));
6473 if E
= Standard_Void_Type
then
6477 -- Special case non-scalar'Size since this is a common error
6479 if Attribute_Name
(N
) = Name_Size
then
6481 ("!size attribute is only static for static scalar type "
6482 & "(RM 4.9(7,8))", N
);
6486 elsif Is_Array_Type
(E
) then
6487 if not Nam_In
(Attribute_Name
(N
), Name_First
,
6492 ("!static array attribute must be Length, First, or Last "
6493 & "(RM 4.9(8))", N
);
6495 -- Since we know the expression is not-static (we already
6496 -- tested for this, must mean array is not static).
6500 ("!prefix is non-static array (RM 4.9(8))", Prefix
(N
));
6505 -- Special case generic types, since again this is a common source
6508 elsif Is_Generic_Actual_Type
(E
) or else Is_Generic_Type
(E
) then
6510 ("!attribute of generic type is never static "
6511 & "(RM 4.9(7,8))", N
);
6513 elsif Is_OK_Static_Subtype
(E
) then
6516 elsif Is_Scalar_Type
(E
) then
6518 ("!prefix type for attribute is not static scalar subtype "
6519 & "(RM 4.9(7))", N
);
6523 ("!static attribute must apply to array/scalar type "
6524 & "(RM 4.9(7,8))", N
);
6529 when N_String_Literal
=>
6531 ("!subtype of string literal is non-static (RM 4.9(4))", N
);
6533 -- Explicit dereference
6535 when N_Explicit_Dereference
=>
6537 ("!explicit dereference is never static (RM 4.9)", N
);
6541 when N_Function_Call
=>
6542 Why_Not_Static_List
(Parameter_Associations
(N
));
6544 -- Complain about non-static function call unless we have Bignum
6545 -- which means that the underlying expression is really some
6546 -- scalar arithmetic operation.
6548 if not Is_RTE
(Typ
, RE_Bignum
) then
6549 Error_Msg_N
("!non-static function call (RM 4.9(6,18))", N
);
6552 -- Parameter assocation (test actual parameter)
6554 when N_Parameter_Association
=>
6555 Why_Not_Static
(Explicit_Actual_Parameter
(N
));
6557 -- Indexed component
6559 when N_Indexed_Component
=>
6560 Error_Msg_N
("!indexed component is never static (RM 4.9)", N
);
6564 when N_Procedure_Call_Statement
=>
6565 Error_Msg_N
("!procedure call is never static (RM 4.9)", N
);
6567 -- Qualified expression (test expression)
6569 when N_Qualified_Expression
=>
6570 Why_Not_Static
(Expression
(N
));
6574 when N_Aggregate | N_Extension_Aggregate
=>
6575 Error_Msg_N
("!an aggregate is never static (RM 4.9)", N
);
6580 Why_Not_Static
(Low_Bound
(N
));
6581 Why_Not_Static
(High_Bound
(N
));
6583 -- Range constraint, test range expression
6585 when N_Range_Constraint
=>
6586 Why_Not_Static
(Range_Expression
(N
));
6588 -- Subtype indication, test constraint
6590 when N_Subtype_Indication
=>
6591 Why_Not_Static
(Constraint
(N
));
6593 -- Selected component
6595 when N_Selected_Component
=>
6596 Error_Msg_N
("!selected component is never static (RM 4.9)", N
);
6601 Error_Msg_N
("!slice is never static (RM 4.9)", N
);
6603 when N_Type_Conversion
=>
6604 Why_Not_Static
(Expression
(N
));
6606 if not Is_Scalar_Type
(Entity
(Subtype_Mark
(N
)))
6607 or else not Is_OK_Static_Subtype
(Entity
(Subtype_Mark
(N
)))
6610 ("!static conversion requires static scalar subtype result "
6611 & "(RM 4.9(9))", N
);
6614 -- Unchecked type conversion
6616 when N_Unchecked_Type_Conversion
=>
6618 ("!unchecked type conversion is never static (RM 4.9)", N
);
6620 -- All other cases, no reason to give