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chromium / native_client / pnacl-gcc / cf3f40121df7fd852a0942d12170bdaea3c22651 / . / gcc / ada / sem_eval.adb
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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ E V A L --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2011, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Atree; use Atree;
with Checks; use Checks;
with Debug; use Debug;
with Einfo; use Einfo;
with Elists; use Elists;
with Errout; use Errout;
with Eval_Fat; use Eval_Fat;
with Exp_Util; use Exp_Util;
with Freeze; use Freeze;
with Lib; use Lib;
with Namet; use Namet;
with Nmake; use Nmake;
with Nlists; use Nlists;
with Opt; use Opt;
with Sem; use Sem;
with Sem_Aux; use Sem_Aux;
with Sem_Cat; use Sem_Cat;
with Sem_Ch6; use Sem_Ch6;
with Sem_Ch8; use Sem_Ch8;
with Sem_Res; use Sem_Res;
with Sem_Util; use Sem_Util;
with Sem_Type; use Sem_Type;
with Sem_Warn; use Sem_Warn;
with Sinfo; use Sinfo;
with Snames; use Snames;
with Stand; use Stand;
with Stringt; use Stringt;
with Tbuild; use Tbuild;
package body Sem_Eval is
-----------------------------------------
-- Handling of Compile Time Evaluation --
-----------------------------------------
-- The compile time evaluation of expressions is distributed over several
-- Eval_xxx procedures. These procedures are called immediately after
-- a subexpression is resolved and is therefore accomplished in a bottom
-- up fashion. The flags are synthesized using the following approach.
-- Is_Static_Expression is determined by following the detailed rules
-- in RM 4.9(4-14). This involves testing the Is_Static_Expression
-- flag of the operands in many cases.
-- Raises_Constraint_Error is set if any of the operands have the flag
-- set or if an attempt to compute the value of the current expression
-- results in detection of a runtime constraint error.
-- As described in the spec, the requirement is that Is_Static_Expression
-- be accurately set, and in addition for nodes for which this flag is set,
-- Raises_Constraint_Error must also be set. Furthermore a node which has
-- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
-- requirement is that the expression value must be precomputed, and the
-- node is either a literal, or the name of a constant entity whose value
-- is a static expression.
-- The general approach is as follows. First compute Is_Static_Expression.
-- If the node is not static, then the flag is left off in the node and
-- we are all done. Otherwise for a static node, we test if any of the
-- operands will raise constraint error, and if so, propagate the flag
-- Raises_Constraint_Error to the result node and we are done (since the
-- error was already posted at a lower level).
-- For the case of a static node whose operands do not raise constraint
-- error, we attempt to evaluate the node. If this evaluation succeeds,
-- then the node is replaced by the result of this computation. If the
-- evaluation raises constraint error, then we rewrite the node with
-- Apply_Compile_Time_Constraint_Error to raise the exception and also
-- to post appropriate error messages.
----------------
-- Local Data --
----------------
type Bits is array (Nat range <>) of Boolean;
-- Used to convert unsigned (modular) values for folding logical ops
-- The following definitions are used to maintain a cache of nodes that
-- have compile time known values. The cache is maintained only for
-- discrete types (the most common case), and is populated by calls to
-- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
-- since it is possible for the status to change (in particular it is
-- possible for a node to get replaced by a constraint error node).
CV_Bits : constant := 5;
-- Number of low order bits of Node_Id value used to reference entries
-- in the cache table.
CV_Cache_Size : constant Nat := 2 ** CV_Bits;
-- Size of cache for compile time values
subtype CV_Range is Nat range 0 .. CV_Cache_Size;
type CV_Entry is record
N : Node_Id;
V : Uint;
end record;
type CV_Cache_Array is array (CV_Range) of CV_Entry;
CV_Cache : CV_Cache_Array := (others => (Node_High_Bound, Uint_0));
-- This is the actual cache, with entries consisting of node/value pairs,
-- and the impossible value Node_High_Bound used for unset entries.
type Range_Membership is (In_Range, Out_Of_Range, Unknown);
-- Range membership may either be statically known to be in range or out
-- of range, or not statically known. Used for Test_In_Range below.
-----------------------
-- Local Subprograms --
-----------------------
function From_Bits (B : Bits; T : Entity_Id) return Uint;
-- Converts a bit string of length B'Length to a Uint value to be used
-- for a target of type T, which is a modular type. This procedure
-- includes the necessary reduction by the modulus in the case of a
-- non-binary modulus (for a binary modulus, the bit string is the
-- right length any way so all is well).
function Get_String_Val (N : Node_Id) return Node_Id;
-- Given a tree node for a folded string or character value, returns
-- the corresponding string literal or character literal (one of the
-- two must be available, or the operand would not have been marked
-- as foldable in the earlier analysis of the operation).
function OK_Bits (N : Node_Id; Bits : Uint) return Boolean;
-- Bits represents the number of bits in an integer value to be computed
-- (but the value has not been computed yet). If this value in Bits is
-- reasonable, a result of True is returned, with the implication that
-- the caller should go ahead and complete the calculation. If the value
-- in Bits is unreasonably large, then an error is posted on node N, and
-- False is returned (and the caller skips the proposed calculation).
procedure Out_Of_Range (N : Node_Id);
-- This procedure is called if it is determined that node N, which
-- appears in a non-static context, is a compile time known value
-- which is outside its range, i.e. the range of Etype. This is used
-- in contexts where this is an illegality if N is static, and should
-- generate a warning otherwise.
procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id);
-- N and Exp are nodes representing an expression, Exp is known
-- to raise CE. N is rewritten in term of Exp in the optimal way.
function String_Type_Len (Stype : Entity_Id) return Uint;
-- Given a string type, determines the length of the index type, or,
-- if this index type is non-static, the length of the base type of
-- this index type. Note that if the string type is itself static,
-- then the index type is static, so the second case applies only
-- if the string type passed is non-static.
function Test (Cond : Boolean) return Uint;
pragma Inline (Test);
-- This function simply returns the appropriate Boolean'Pos value
-- corresponding to the value of Cond as a universal integer. It is
-- used for producing the result of the static evaluation of the
-- logical operators
function Find_Universal_Operator_Type (N : Node_Id) return Entity_Id;
-- Check whether an arithmetic operation with universal operands which
-- is a rewritten function call with an explicit scope indication is
-- ambiguous: P."+" (1, 2) will be ambiguous if there is more than one
-- visible numeric type declared in P and the context does not impose a
-- type on the result (e.g. in the expression of a type conversion).
-- If ambiguous, emit an error and return Empty, else return the result
-- type of the operator.
procedure Test_Expression_Is_Foldable
(N : Node_Id;
Op1 : Node_Id;
Stat : out Boolean;
Fold : out Boolean);
-- Tests to see if expression N whose single operand is Op1 is foldable,
-- i.e. the operand value is known at compile time. If the operation is
-- foldable, then Fold is True on return, and Stat indicates whether
-- the result is static (i.e. both operands were static). Note that it
-- is quite possible for Fold to be True, and Stat to be False, since
-- there are cases in which we know the value of an operand even though
-- it is not technically static (e.g. the static lower bound of a range
-- whose upper bound is non-static).
--
-- If Stat is set False on return, then Test_Expression_Is_Foldable makes a
-- call to Check_Non_Static_Context on the operand. If Fold is False on
-- return, then all processing is complete, and the caller should
-- return, since there is nothing else to do.
--
-- If Stat is set True on return, then Is_Static_Expression is also set
-- true in node N. There are some cases where this is over-enthusiastic,
-- e.g. in the two operand case below, for string comparison, the result
-- is not static even though the two operands are static. In such cases,
-- the caller must reset the Is_Static_Expression flag in N.
procedure Test_Expression_Is_Foldable
(N : Node_Id;
Op1 : Node_Id;
Op2 : Node_Id;
Stat : out Boolean;
Fold : out Boolean);
-- Same processing, except applies to an expression N with two operands
-- Op1 and Op2.
function Test_In_Range
(N : Node_Id;
Typ : Entity_Id;
Assume_Valid : Boolean;
Fixed_Int : Boolean;
Int_Real : Boolean) return Range_Membership;
-- Common processing for Is_In_Range and Is_Out_Of_Range:
-- Returns In_Range or Out_Of_Range if it can be guaranteed at compile time
-- that expression N is known to be in or out of range of the subtype Typ.
-- If not compile time known, Unknown is returned.
-- See documentation of Is_In_Range for complete description of parameters.
procedure To_Bits (U : Uint; B : out Bits);
-- Converts a Uint value to a bit string of length B'Length
------------------------------
-- Check_Non_Static_Context --
------------------------------
procedure Check_Non_Static_Context (N : Node_Id) is
T : constant Entity_Id := Etype (N);
Checks_On : constant Boolean :=
not Index_Checks_Suppressed (T)
and not Range_Checks_Suppressed (T);
begin
-- Ignore cases of non-scalar types or error types
if T = Any_Type or else not Is_Scalar_Type (T) then
return;
end if;
-- At this stage we have a scalar type. If we have an expression
-- that raises CE, then we already issued a warning or error msg
-- so there is nothing more to be done in this routine.
if Raises_Constraint_Error (N) then
return;
end if;
-- Now we have a scalar type which is not marked as raising a
-- constraint error exception. The main purpose of this routine
-- is to deal with static expressions appearing in a non-static
-- context. That means that if we do not have a static expression
-- then there is not much to do. The one case that we deal with
-- here is that if we have a floating-point value that is out of
-- range, then we post a warning that an infinity will result.
if not Is_Static_Expression (N) then
if Is_Floating_Point_Type (T)
and then Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True)
then
Error_Msg_N
("?float value out of range, infinity will be generated", N);
end if;
return;
end if;
-- Here we have the case of outer level static expression of
-- scalar type, where the processing of this procedure is needed.
-- For real types, this is where we convert the value to a machine
-- number (see RM 4.9(38)). Also see ACVC test C490001. We should
-- only need to do this if the parent is a constant declaration,
-- since in other cases, gigi should do the necessary conversion
-- correctly, but experimentation shows that this is not the case
-- on all machines, in particular if we do not convert all literals
-- to machine values in non-static contexts, then ACVC test C490001
-- fails on Sparc/Solaris and SGI/Irix.
if Nkind (N) = N_Real_Literal
and then not Is_Machine_Number (N)
and then not Is_Generic_Type (Etype (N))
and then Etype (N) /= Universal_Real
then
-- Check that value is in bounds before converting to machine
-- number, so as not to lose case where value overflows in the
-- least significant bit or less. See B490001.
if Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True) then
Out_Of_Range (N);
return;
end if;
-- Note: we have to copy the node, to avoid problems with conformance
-- of very similar numbers (see ACVC tests B4A010C and B63103A).
Rewrite (N, New_Copy (N));
if not Is_Floating_Point_Type (T) then
Set_Realval
(N, Corresponding_Integer_Value (N) * Small_Value (T));
elsif not UR_Is_Zero (Realval (N)) then
-- Note: even though RM 4.9(38) specifies biased rounding,
-- this has been modified by AI-100 in order to prevent
-- confusing differences in rounding between static and
-- non-static expressions. AI-100 specifies that the effect
-- of such rounding is implementation dependent, and in GNAT
-- we round to nearest even to match the run-time behavior.
Set_Realval
(N, Machine (Base_Type (T), Realval (N), Round_Even, N));
end if;
Set_Is_Machine_Number (N);
end if;
-- Check for out of range universal integer. This is a non-static
-- context, so the integer value must be in range of the runtime
-- representation of universal integers.
-- We do this only within an expression, because that is the only
-- case in which non-static universal integer values can occur, and
-- furthermore, Check_Non_Static_Context is currently (incorrectly???)
-- called in contexts like the expression of a number declaration where
-- we certainly want to allow out of range values.
if Etype (N) = Universal_Integer
and then Nkind (N) = N_Integer_Literal
and then Nkind (Parent (N)) in N_Subexpr
and then
(Intval (N) < Expr_Value (Type_Low_Bound (Universal_Integer))
or else
Intval (N) > Expr_Value (Type_High_Bound (Universal_Integer)))
then
Apply_Compile_Time_Constraint_Error
(N, "non-static universal integer value out of range?",
CE_Range_Check_Failed);
-- Check out of range of base type
elsif Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True) then
Out_Of_Range (N);
-- Give warning if outside subtype (where one or both of the bounds of
-- the subtype is static). This warning is omitted if the expression
-- appears in a range that could be null (warnings are handled elsewhere
-- for this case).
elsif T /= Base_Type (T)
and then Nkind (Parent (N)) /= N_Range
then
if Is_In_Range (N, T, Assume_Valid => True) then
null;
elsif Is_Out_Of_Range (N, T, Assume_Valid => True) then
Apply_Compile_Time_Constraint_Error
(N, "value not in range of}?", CE_Range_Check_Failed);
elsif Checks_On then
Enable_Range_Check (N);
else
Set_Do_Range_Check (N, False);
end if;
end if;
end Check_Non_Static_Context;
---------------------------------
-- Check_String_Literal_Length --
---------------------------------
procedure Check_String_Literal_Length (N : Node_Id; Ttype : Entity_Id) is
begin
if not Raises_Constraint_Error (N)
and then Is_Constrained (Ttype)
then
if
UI_From_Int (String_Length (Strval (N))) /= String_Type_Len (Ttype)
then
Apply_Compile_Time_Constraint_Error
(N, "string length wrong for}?",
CE_Length_Check_Failed,
Ent => Ttype,
Typ => Ttype);
end if;
end if;
end Check_String_Literal_Length;
--------------------------
-- Compile_Time_Compare --
--------------------------
function Compile_Time_Compare
(L, R : Node_Id;
Assume_Valid : Boolean) return Compare_Result
is
Discard : aliased Uint;
begin
return Compile_Time_Compare (L, R, Discard'Access, Assume_Valid);
end Compile_Time_Compare;
function Compile_Time_Compare
(L, R : Node_Id;
Diff : access Uint;
Assume_Valid : Boolean;
Rec : Boolean := False) return Compare_Result
is
Ltyp : Entity_Id := Underlying_Type (Etype (L));
Rtyp : Entity_Id := Underlying_Type (Etype (R));
-- These get reset to the base type for the case of entities where
-- Is_Known_Valid is not set. This takes care of handling possible
-- invalid representations using the value of the base type, in
-- accordance with RM 13.9.1(10).
Discard : aliased Uint;
procedure Compare_Decompose
(N : Node_Id;
R : out Node_Id;
V : out Uint);
-- This procedure decomposes the node N into an expression node and a
-- signed offset, so that the value of N is equal to the value of R plus
-- the value V (which may be negative). If no such decomposition is
-- possible, then on return R is a copy of N, and V is set to zero.
function Compare_Fixup (N : Node_Id) return Node_Id;
-- This function deals with replacing 'Last and 'First references with
-- their corresponding type bounds, which we then can compare. The
-- argument is the original node, the result is the identity, unless we
-- have a 'Last/'First reference in which case the value returned is the
-- appropriate type bound.
function Is_Known_Valid_Operand (Opnd : Node_Id) return Boolean;
-- Even if the context does not assume that values are valid, some
-- simple cases can be recognized.
function Is_Same_Value (L, R : Node_Id) return Boolean;
-- Returns True iff L and R represent expressions that definitely
-- have identical (but not necessarily compile time known) values
-- Indeed the caller is expected to have already dealt with the
-- cases of compile time known values, so these are not tested here.
-----------------------
-- Compare_Decompose --
-----------------------
procedure Compare_Decompose
(N : Node_Id;
R : out Node_Id;
V : out Uint)
is
begin
if Nkind (N) = N_Op_Add
and then Nkind (Right_Opnd (N)) = N_Integer_Literal
then
R := Left_Opnd (N);
V := Intval (Right_Opnd (N));
return;
elsif Nkind (N) = N_Op_Subtract
and then Nkind (Right_Opnd (N)) = N_Integer_Literal
then
R := Left_Opnd (N);
V := UI_Negate (Intval (Right_Opnd (N)));
return;
elsif Nkind (N) = N_Attribute_Reference then
if Attribute_Name (N) = Name_Succ then
R := First (Expressions (N));
V := Uint_1;
return;
elsif Attribute_Name (N) = Name_Pred then
R := First (Expressions (N));
V := Uint_Minus_1;
return;
end if;
end if;
R := N;
V := Uint_0;
end Compare_Decompose;
-------------------
-- Compare_Fixup --
-------------------
function Compare_Fixup (N : Node_Id) return Node_Id is
Indx : Node_Id;
Xtyp : Entity_Id;
Subs : Nat;
begin
if Nkind (N) = N_Attribute_Reference
and then (Attribute_Name (N) = Name_First
or else
Attribute_Name (N) = Name_Last)
then
Xtyp := Etype (Prefix (N));
-- If we have no type, then just abandon the attempt to do
-- a fixup, this is probably the result of some other error.
if No (Xtyp) then
return N;
end if;
-- Dereference an access type
if Is_Access_Type (Xtyp) then
Xtyp := Designated_Type (Xtyp);
end if;
-- If we don't have an array type at this stage, something
-- is peculiar, e.g. another error, and we abandon the attempt
-- at a fixup.
if not Is_Array_Type (Xtyp) then
return N;
end if;
-- Ignore unconstrained array, since bounds are not meaningful
if not Is_Constrained (Xtyp) then
return N;
end if;
if Ekind (Xtyp) = E_String_Literal_Subtype then
if Attribute_Name (N) = Name_First then
return String_Literal_Low_Bound (Xtyp);
else -- Attribute_Name (N) = Name_Last
return Make_Integer_Literal (Sloc (N),
Intval => Intval (String_Literal_Low_Bound (Xtyp))
+ String_Literal_Length (Xtyp));
end if;
end if;
-- Find correct index type
Indx := First_Index (Xtyp);
if Present (Expressions (N)) then
Subs := UI_To_Int (Expr_Value (First (Expressions (N))));
for J in 2 .. Subs loop
Indx := Next_Index (Indx);
end loop;
end if;
Xtyp := Etype (Indx);
if Attribute_Name (N) = Name_First then
return Type_Low_Bound (Xtyp);
else -- Attribute_Name (N) = Name_Last
return Type_High_Bound (Xtyp);
end if;
end if;
return N;
end Compare_Fixup;
----------------------------
-- Is_Known_Valid_Operand --
----------------------------
function Is_Known_Valid_Operand (Opnd : Node_Id) return Boolean is
begin
return (Is_Entity_Name (Opnd)
and then
(Is_Known_Valid (Entity (Opnd))
or else Ekind (Entity (Opnd)) = E_In_Parameter
or else
(Ekind (Entity (Opnd)) in Object_Kind
and then Present (Current_Value (Entity (Opnd))))))
or else Is_OK_Static_Expression (Opnd);
end Is_Known_Valid_Operand;
-------------------
-- Is_Same_Value --
-------------------
function Is_Same_Value (L, R : Node_Id) return Boolean is
Lf : constant Node_Id := Compare_Fixup (L);
Rf : constant Node_Id := Compare_Fixup (R);
function Is_Same_Subscript (L, R : List_Id) return Boolean;
-- L, R are the Expressions values from two attribute nodes for First
-- or Last attributes. Either may be set to No_List if no expressions
-- are present (indicating subscript 1). The result is True if both
-- expressions represent the same subscript (note one case is where
-- one subscript is missing and the other is explicitly set to 1).
-----------------------
-- Is_Same_Subscript --
-----------------------
function Is_Same_Subscript (L, R : List_Id) return Boolean is
begin
if L = No_List then
if R = No_List then
return True;
else
return Expr_Value (First (R)) = Uint_1;
end if;
else
if R = No_List then
return Expr_Value (First (L)) = Uint_1;
else
return Expr_Value (First (L)) = Expr_Value (First (R));
end if;
end if;
end Is_Same_Subscript;
-- Start of processing for Is_Same_Value
begin
-- Values are the same if they refer to the same entity and the
-- entity is non-volatile. This does not however apply to Float
-- types, since we may have two NaN values and they should never
-- compare equal.
-- If the entity is a discriminant, the two expressions may be bounds
-- of components of objects of the same discriminated type. The
-- values of the discriminants are not static, and therefore the
-- result is unknown.
-- It would be better to comment individual branches of this test ???
if Nkind_In (Lf, N_Identifier, N_Expanded_Name)
and then Nkind_In (Rf, N_Identifier, N_Expanded_Name)
and then Entity (Lf) = Entity (Rf)
and then Ekind (Entity (Lf)) /= E_Discriminant
and then Present (Entity (Lf))
and then not Is_Floating_Point_Type (Etype (L))
and then not Is_Volatile_Reference (L)
and then not Is_Volatile_Reference (R)
then
return True;
-- Or if they are compile time known and identical
elsif Compile_Time_Known_Value (Lf)
and then
Compile_Time_Known_Value (Rf)
and then Expr_Value (Lf) = Expr_Value (Rf)
then
return True;
-- False if Nkind of the two nodes is different for remaining cases
elsif Nkind (Lf) /= Nkind (Rf) then
return False;
-- True if both 'First or 'Last values applying to the same entity
-- (first and last don't change even if value does). Note that we
-- need this even with the calls to Compare_Fixup, to handle the
-- case of unconstrained array attributes where Compare_Fixup
-- cannot find useful bounds.
elsif Nkind (Lf) = N_Attribute_Reference
and then Attribute_Name (Lf) = Attribute_Name (Rf)
and then (Attribute_Name (Lf) = Name_First
or else
Attribute_Name (Lf) = Name_Last)
and then Nkind_In (Prefix (Lf), N_Identifier, N_Expanded_Name)
and then Nkind_In (Prefix (Rf), N_Identifier, N_Expanded_Name)
and then Entity (Prefix (Lf)) = Entity (Prefix (Rf))
and then Is_Same_Subscript (Expressions (Lf), Expressions (Rf))
then
return True;
-- True if the same selected component from the same record
elsif Nkind (Lf) = N_Selected_Component
and then Selector_Name (Lf) = Selector_Name (Rf)
and then Is_Same_Value (Prefix (Lf), Prefix (Rf))
then
return True;
-- True if the same unary operator applied to the same operand
elsif Nkind (Lf) in N_Unary_Op
and then Is_Same_Value (Right_Opnd (Lf), Right_Opnd (Rf))
then
return True;
-- True if the same binary operator applied to the same operands
elsif Nkind (Lf) in N_Binary_Op
and then Is_Same_Value (Left_Opnd (Lf), Left_Opnd (Rf))
and then Is_Same_Value (Right_Opnd (Lf), Right_Opnd (Rf))
then
return True;
-- All other cases, we can't tell, so return False
else
return False;
end if;
end Is_Same_Value;
-- Start of processing for Compile_Time_Compare
begin
Diff.all := No_Uint;
-- If either operand could raise constraint error, then we cannot
-- know the result at compile time (since CE may be raised!)
if not (Cannot_Raise_Constraint_Error (L)
and then
Cannot_Raise_Constraint_Error (R))
then
return Unknown;
end if;
-- Identical operands are most certainly equal
if L = R then
return EQ;
-- If expressions have no types, then do not attempt to determine if
-- they are the same, since something funny is going on. One case in
-- which this happens is during generic template analysis, when bounds
-- are not fully analyzed.
elsif No (Ltyp) or else No (Rtyp) then
return Unknown;
-- We do not attempt comparisons for packed arrays arrays represented as
-- modular types, where the semantics of comparison is quite different.
elsif Is_Packed_Array_Type (Ltyp)
and then Is_Modular_Integer_Type (Ltyp)
then
return Unknown;
-- For access types, the only time we know the result at compile time
-- (apart from identical operands, which we handled already) is if we
-- know one operand is null and the other is not, or both operands are
-- known null.
elsif Is_Access_Type (Ltyp) then
if Known_Null (L) then
if Known_Null (R) then
return EQ;
elsif Known_Non_Null (R) then
return NE;
else
return Unknown;
end if;
elsif Known_Non_Null (L) and then Known_Null (R) then
return NE;
else
return Unknown;
end if;
-- Case where comparison involves two compile time known values
elsif Compile_Time_Known_Value (L)
and then Compile_Time_Known_Value (R)
then
-- For the floating-point case, we have to be a little careful, since
-- at compile time we are dealing with universal exact values, but at
-- runtime, these will be in non-exact target form. That's why the
-- returned results are LE and GE below instead of LT and GT.
if Is_Floating_Point_Type (Ltyp)
or else
Is_Floating_Point_Type (Rtyp)
then
declare
Lo : constant Ureal := Expr_Value_R (L);
Hi : constant Ureal := Expr_Value_R (R);
begin
if Lo < Hi then
return LE;
elsif Lo = Hi then
return EQ;
else
return GE;
end if;
end;
-- For string types, we have two string literals and we proceed to
-- compare them using the Ada style dictionary string comparison.
elsif not Is_Scalar_Type (Ltyp) then
declare
Lstring : constant String_Id := Strval (Expr_Value_S (L));
Rstring : constant String_Id := Strval (Expr_Value_S (R));
Llen : constant Nat := String_Length (Lstring);
Rlen : constant Nat := String_Length (Rstring);
begin
for J in 1 .. Nat'Min (Llen, Rlen) loop
declare
LC : constant Char_Code := Get_String_Char (Lstring, J);
RC : constant Char_Code := Get_String_Char (Rstring, J);
begin
if LC < RC then
return LT;
elsif LC > RC then
return GT;
end if;
end;
end loop;
if Llen < Rlen then
return LT;
elsif Llen > Rlen then
return GT;
else
return EQ;
end if;
end;
-- For remaining scalar cases we know exactly (note that this does
-- include the fixed-point case, where we know the run time integer
-- values now).
else
declare
Lo : constant Uint := Expr_Value (L);
Hi : constant Uint := Expr_Value (R);
begin
if Lo < Hi then
Diff.all := Hi - Lo;
return LT;
elsif Lo = Hi then
return EQ;
else
Diff.all := Lo - Hi;
return GT;
end if;
end;
end if;
-- Cases where at least one operand is not known at compile time
else
-- Remaining checks apply only for discrete types
if not Is_Discrete_Type (Ltyp)
or else not Is_Discrete_Type (Rtyp)
then
return Unknown;
end if;
-- Defend against generic types, or actually any expressions that
-- contain a reference to a generic type from within a generic
-- template. We don't want to do any range analysis of such
-- expressions for two reasons. First, the bounds of a generic type
-- itself are junk and cannot be used for any kind of analysis.
-- Second, we may have a case where the range at run time is indeed
-- known, but we don't want to do compile time analysis in the
-- template based on that range since in an instance the value may be
-- static, and able to be elaborated without reference to the bounds
-- of types involved. As an example, consider:
-- (F'Pos (F'Last) + 1) > Integer'Last
-- The expression on the left side of > is Universal_Integer and thus
-- acquires the type Integer for evaluation at run time, and at run
-- time it is true that this condition is always False, but within
-- an instance F may be a type with a static range greater than the
-- range of Integer, and the expression statically evaluates to True.
if References_Generic_Formal_Type (L)
or else
References_Generic_Formal_Type (R)
then
return Unknown;
end if;
-- Replace types by base types for the case of entities which are
-- not known to have valid representations. This takes care of
-- properly dealing with invalid representations.
if not Assume_Valid and then not Assume_No_Invalid_Values then
if Is_Entity_Name (L) and then not Is_Known_Valid (Entity (L)) then
Ltyp := Underlying_Type (Base_Type (Ltyp));
end if;
if Is_Entity_Name (R) and then not Is_Known_Valid (Entity (R)) then
Rtyp := Underlying_Type (Base_Type (Rtyp));
end if;
end if;
-- Try range analysis on variables and see if ranges are disjoint
declare
LOK, ROK : Boolean;
LLo, LHi : Uint;
RLo, RHi : Uint;
begin
Determine_Range (L, LOK, LLo, LHi, Assume_Valid);
Determine_Range (R, ROK, RLo, RHi, Assume_Valid);
if LOK and ROK then
if LHi < RLo then
return LT;
elsif RHi < LLo then
return GT;
elsif LLo = LHi
and then RLo = RHi
and then LLo = RLo
then
-- If the range includes a single literal and we can assume
-- validity then the result is known even if an operand is
-- not static.
if Assume_Valid then
return EQ;
else
return Unknown;
end if;
elsif LHi = RLo then
return LE;
elsif RHi = LLo then
return GE;
elsif not Is_Known_Valid_Operand (L)
and then not Assume_Valid
then
if Is_Same_Value (L, R) then
return EQ;
else
return Unknown;
end if;
end if;
-- If the range of either operand cannot be determined, nothing
-- further can be inferred.
else
return Unknown;
end if;
end;
-- Here is where we check for comparisons against maximum bounds of
-- types, where we know that no value can be outside the bounds of
-- the subtype. Note that this routine is allowed to assume that all
-- expressions are within their subtype bounds. Callers wishing to
-- deal with possibly invalid values must in any case take special
-- steps (e.g. conversions to larger types) to avoid this kind of
-- optimization, which is always considered to be valid. We do not
-- attempt this optimization with generic types, since the type
-- bounds may not be meaningful in this case.
-- We are in danger of an infinite recursion here. It does not seem
-- useful to go more than one level deep, so the parameter Rec is
-- used to protect ourselves against this infinite recursion.
if not Rec then
-- See if we can get a decisive check against one operand and
-- a bound of the other operand (four possible tests here).
-- Note that we avoid testing junk bounds of a generic type.
if not Is_Generic_Type (Rtyp) then
case Compile_Time_Compare (L, Type_Low_Bound (Rtyp),
Discard'Access,
Assume_Valid, Rec => True)
is
when LT => return LT;
when LE => return LE;
when EQ => return LE;
when others => null;
end case;
case Compile_Time_Compare (L, Type_High_Bound (Rtyp),
Discard'Access,
Assume_Valid, Rec => True)
is
when GT => return GT;
when GE => return GE;
when EQ => return GE;
when others => null;
end case;
end if;
if not Is_Generic_Type (Ltyp) then
case Compile_Time_Compare (Type_Low_Bound (Ltyp), R,
Discard'Access,
Assume_Valid, Rec => True)
is
when GT => return GT;
when GE => return GE;
when EQ => return GE;
when others => null;
end case;
case Compile_Time_Compare (Type_High_Bound (Ltyp), R,
Discard'Access,
Assume_Valid, Rec => True)
is
when LT => return LT;
when LE => return LE;
when EQ => return LE;
when others => null;
end case;
end if;
end if;
-- Next attempt is to decompose the expressions to extract
-- a constant offset resulting from the use of any of the forms:
-- expr + literal
-- expr - literal
-- typ'Succ (expr)
-- typ'Pred (expr)
-- Then we see if the two expressions are the same value, and if so
-- the result is obtained by comparing the offsets.
declare
Lnode : Node_Id;
Loffs : Uint;
Rnode : Node_Id;
Roffs : Uint;
begin
Compare_Decompose (L, Lnode, Loffs);
Compare_Decompose (R, Rnode, Roffs);
if Is_Same_Value (Lnode, Rnode) then
if Loffs = Roffs then
return EQ;
elsif Loffs < Roffs then
Diff.all := Roffs - Loffs;
return LT;
else
Diff.all := Loffs - Roffs;
return GT;
end if;
end if;
end;
-- Next attempt is to see if we have an entity compared with a
-- compile time known value, where there is a current value
-- conditional for the entity which can tell us the result.
declare
Var : Node_Id;
-- Entity variable (left operand)
Val : Uint;
-- Value (right operand)
Inv : Boolean;
-- If False, we have reversed the operands
Op : Node_Kind;
-- Comparison operator kind from Get_Current_Value_Condition call
Opn : Node_Id;
-- Value from Get_Current_Value_Condition call
Opv : Uint;
-- Value of Opn
Result : Compare_Result;
-- Known result before inversion
begin
if Is_Entity_Name (L)
and then Compile_Time_Known_Value (R)
then
Var := L;
Val := Expr_Value (R);
Inv := False;
elsif Is_Entity_Name (R)
and then Compile_Time_Known_Value (L)
then
Var := R;
Val := Expr_Value (L);
Inv := True;
-- That was the last chance at finding a compile time result
else
return Unknown;
end if;
Get_Current_Value_Condition (Var, Op, Opn);
-- That was the last chance, so if we got nothing return
if No (Opn) then
return Unknown;
end if;
Opv := Expr_Value (Opn);
-- We got a comparison, so we might have something interesting
-- Convert LE to LT and GE to GT, just so we have fewer cases
if Op = N_Op_Le then
Op := N_Op_Lt;
Opv := Opv + 1;
elsif Op = N_Op_Ge then
Op := N_Op_Gt;
Opv := Opv - 1;
end if;
-- Deal with equality case
if Op = N_Op_Eq then
if Val = Opv then
Result := EQ;
elsif Opv < Val then
Result := LT;
else
Result := GT;
end if;
-- Deal with inequality case
elsif Op = N_Op_Ne then
if Val = Opv then
Result := NE;
else
return Unknown;
end if;
-- Deal with greater than case
elsif Op = N_Op_Gt then
if Opv >= Val then
Result := GT;
elsif Opv = Val - 1 then
Result := GE;
else
return Unknown;
end if;
-- Deal with less than case
else pragma Assert (Op = N_Op_Lt);
if Opv <= Val then
Result := LT;
elsif Opv = Val + 1 then
Result := LE;
else
return Unknown;
end if;
end if;
-- Deal with inverting result
if Inv then
case Result is
when GT => return LT;
when GE => return LE;
when LT => return GT;
when LE => return GE;
when others => return Result;
end case;
end if;
return Result;
end;
end if;
end Compile_Time_Compare;
-------------------------------
-- Compile_Time_Known_Bounds --
-------------------------------
function Compile_Time_Known_Bounds (T : Entity_Id) return Boolean is
Indx : Node_Id;
Typ : Entity_Id;
begin
if not Is_Array_Type (T) then
return False;
end if;
Indx := First_Index (T);
while Present (Indx) loop
Typ := Underlying_Type (Etype (Indx));
-- Never look at junk bounds of a generic type
if Is_Generic_Type (Typ) then
return False;
end if;
-- Otherwise check bounds for compile time known
if not Compile_Time_Known_Value (Type_Low_Bound (Typ)) then
return False;
elsif not Compile_Time_Known_Value (Type_High_Bound (Typ)) then
return False;
else
Next_Index (Indx);
end if;
end loop;
return True;
end Compile_Time_Known_Bounds;
------------------------------
-- Compile_Time_Known_Value --
------------------------------
function Compile_Time_Known_Value (Op : Node_Id) return Boolean is
K : constant Node_Kind := Nkind (Op);
CV_Ent : CV_Entry renames CV_Cache (Nat (Op) mod CV_Cache_Size);
begin
-- Never known at compile time if bad type or raises constraint error
-- or empty (latter case occurs only as a result of a previous error)
if No (Op)
or else Op = Error
or else Etype (Op) = Any_Type
or else Raises_Constraint_Error (Op)
then
return False;
end if;
-- If this is not a static expression or a null literal, and we are in
-- configurable run-time mode, then we consider it not known at compile
-- time. This avoids anomalies where whether something is allowed with a
-- given configurable run-time library depends on how good the compiler
-- is at optimizing and knowing that things are constant when they are
-- nonstatic.
if Configurable_Run_Time_Mode
and then K /= N_Null
and then not Is_Static_Expression (Op)
then
return False;
end if;
-- If we have an entity name, then see if it is the name of a constant
-- and if so, test the corresponding constant value, or the name of
-- an enumeration literal, which is always a constant.
if Present (Etype (Op)) and then Is_Entity_Name (Op) then
declare
E : constant Entity_Id := Entity (Op);
V : Node_Id;
begin
-- Never known at compile time if it is a packed array value.
-- We might want to try to evaluate these at compile time one
-- day, but we do not make that attempt now.
if Is_Packed_Array_Type (Etype (Op)) then
return False;
end if;
if Ekind (E) = E_Enumeration_Literal then
return True;
elsif Ekind (E) = E_Constant then
V := Constant_Value (E);
return Present (V) and then Compile_Time_Known_Value (V);
end if;
end;
-- We have a value, see if it is compile time known
else
-- Integer literals are worth storing in the cache
if K = N_Integer_Literal then
CV_Ent.N := Op;
CV_Ent.V := Intval (Op);
return True;
-- Other literals and NULL are known at compile time
elsif
K = N_Character_Literal
or else
K = N_Real_Literal
or else
K = N_String_Literal
or else
K = N_Null
then
return True;
-- Any reference to Null_Parameter is known at compile time. No
-- other attribute references (that have not already been folded)
-- are known at compile time.
elsif K = N_Attribute_Reference then
return Attribute_Name (Op) = Name_Null_Parameter;
end if;
end if;
-- If we fall through, not known at compile time
return False;
-- If we get an exception while trying to do this test, then some error
-- has occurred, and we simply say that the value is not known after all
exception
when others =>
return False;
end Compile_Time_Known_Value;
--------------------------------------
-- Compile_Time_Known_Value_Or_Aggr --
--------------------------------------
function Compile_Time_Known_Value_Or_Aggr (Op : Node_Id) return Boolean is
begin
-- If we have an entity name, then see if it is the name of a constant
-- and if so, test the corresponding constant value, or the name of
-- an enumeration literal, which is always a constant.
if Is_Entity_Name (Op) then
declare
E : constant Entity_Id := Entity (Op);
V : Node_Id;
begin
if Ekind (E) = E_Enumeration_Literal then
return True;
elsif Ekind (E) /= E_Constant then
return False;
else
V := Constant_Value (E);
return Present (V)
and then Compile_Time_Known_Value_Or_Aggr (V);
end if;
end;
-- We have a value, see if it is compile time known
else
if Compile_Time_Known_Value (Op) then
return True;
elsif Nkind (Op) = N_Aggregate then
if Present (Expressions (Op)) then
declare
Expr : Node_Id;
begin
Expr := First (Expressions (Op));
while Present (Expr) loop
if not Compile_Time_Known_Value_Or_Aggr (Expr) then
return False;
end if;
Next (Expr);
end loop;
end;
end if;
if Present (Component_Associations (Op)) then
declare
Cass : Node_Id;
begin
Cass := First (Component_Associations (Op));
while Present (Cass) loop
if not
Compile_Time_Known_Value_Or_Aggr (Expression (Cass))
then
return False;
end if;
Next (Cass);
end loop;
end;
end if;
return True;
-- All other types of values are not known at compile time
else
return False;
end if;
end if;
end Compile_Time_Known_Value_Or_Aggr;
-----------------
-- Eval_Actual --
-----------------
-- This is only called for actuals of functions that are not predefined
-- operators (which have already been rewritten as operators at this
-- stage), so the call can never be folded, and all that needs doing for
-- the actual is to do the check for a non-static context.
procedure Eval_Actual (N : Node_Id) is
begin
Check_Non_Static_Context (N);
end Eval_Actual;
--------------------
-- Eval_Allocator --
--------------------
-- Allocators are never static, so all we have to do is to do the
-- check for a non-static context if an expression is present.
procedure Eval_Allocator (N : Node_Id) is
Expr : constant Node_Id := Expression (N);
begin
if Nkind (Expr) = N_Qualified_Expression then
Check_Non_Static_Context (Expression (Expr));
end if;
end Eval_Allocator;
------------------------
-- Eval_Arithmetic_Op --
------------------------
-- Arithmetic operations are static functions, so the result is static
-- if both operands are static (RM 4.9(7), 4.9(20)).
procedure Eval_Arithmetic_Op (N : Node_Id) is
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
Ltype : constant Entity_Id := Etype (Left);
Rtype : constant Entity_Id := Etype (Right);
Otype : Entity_Id := Empty;
Stat : Boolean;
Fold : Boolean;
begin
-- If not foldable we are done
Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
if not Fold then
return;
end if;
if Is_Universal_Numeric_Type (Etype (Left))
and then
Is_Universal_Numeric_Type (Etype (Right))
then
Otype := Find_Universal_Operator_Type (N);
end if;
-- Fold for cases where both operands are of integer type
if Is_Integer_Type (Ltype) and then Is_Integer_Type (Rtype) then
declare
Left_Int : constant Uint := Expr_Value (Left);
Right_Int : constant Uint := Expr_Value (Right);
Result : Uint;
begin
case Nkind (N) is
when N_Op_Add =>
Result := Left_Int + Right_Int;
when N_Op_Subtract =>
Result := Left_Int - Right_Int;
when N_Op_Multiply =>
if OK_Bits
(N, UI_From_Int
(Num_Bits (Left_Int) + Num_Bits (Right_Int)))
then
Result := Left_Int * Right_Int;
else
Result := Left_Int;
end if;
when N_Op_Divide =>
-- The exception Constraint_Error is raised by integer
-- division, rem and mod if the right operand is zero.
if Right_Int = 0 then
Apply_Compile_Time_Constraint_Error
(N, "division by zero",
CE_Divide_By_Zero,
Warn => not Stat);
return;
else
Result := Left_Int / Right_Int;
end if;
when N_Op_Mod =>
-- The exception Constraint_Error is raised by integer
-- division, rem and mod if the right operand is zero.
if Right_Int = 0 then
Apply_Compile_Time_Constraint_Error
(N, "mod with zero divisor",
CE_Divide_By_Zero,
Warn => not Stat);
return;
else
Result := Left_Int mod Right_Int;
end if;
when N_Op_Rem =>
-- The exception Constraint_Error is raised by integer
-- division, rem and mod if the right operand is zero.
if Right_Int = 0 then
Apply_Compile_Time_Constraint_Error
(N, "rem with zero divisor",
CE_Divide_By_Zero,
Warn => not Stat);
return;
else
Result := Left_Int rem Right_Int;
end if;
when others =>
raise Program_Error;
end case;
-- Adjust the result by the modulus if the type is a modular type
if Is_Modular_Integer_Type (Ltype) then
Result := Result mod Modulus (Ltype);
-- For a signed integer type, check non-static overflow
elsif (not Stat) and then Is_Signed_Integer_Type (Ltype) then
declare
BT : constant Entity_Id := Base_Type (Ltype);
Lo : constant Uint := Expr_Value (Type_Low_Bound (BT));
Hi : constant Uint := Expr_Value (Type_High_Bound (BT));
begin
if Result < Lo or else Result > Hi then
Apply_Compile_Time_Constraint_Error
(N, "value not in range of }?",
CE_Overflow_Check_Failed,
Ent => BT);
return;
end if;
end;
end if;
-- If we get here we can fold the result
Fold_Uint (N, Result, Stat);
end;
-- Cases where at least one operand is a real. We handle the cases of
-- both reals, or mixed/real integer cases (the latter happen only for
-- divide and multiply, and the result is always real).
elsif Is_Real_Type (Ltype) or else Is_Real_Type (Rtype) then
declare
Left_Real : Ureal;
Right_Real : Ureal;
Result : Ureal;
begin
if Is_Real_Type (Ltype) then
Left_Real := Expr_Value_R (Left);
else
Left_Real := UR_From_Uint (Expr_Value (Left));
end if;
if Is_Real_Type (Rtype) then
Right_Real := Expr_Value_R (Right);
else
Right_Real := UR_From_Uint (Expr_Value (Right));
end if;
if Nkind (N) = N_Op_Add then
Result := Left_Real + Right_Real;
elsif Nkind (N) = N_Op_Subtract then
Result := Left_Real - Right_Real;
elsif Nkind (N) = N_Op_Multiply then
Result := Left_Real * Right_Real;
else pragma Assert (Nkind (N) = N_Op_Divide);
if UR_Is_Zero (Right_Real) then
Apply_Compile_Time_Constraint_Error
(N, "division by zero", CE_Divide_By_Zero);
return;
end if;
Result := Left_Real / Right_Real;
end if;
Fold_Ureal (N, Result, Stat);
end;
end if;
-- If the operator was resolved to a specific type, make sure that type
-- is frozen even if the expression is folded into a literal (which has
-- a universal type).
if Present (Otype) then
Freeze_Before (N, Otype);
end if;
end Eval_Arithmetic_Op;
----------------------------
-- Eval_Character_Literal --
----------------------------
-- Nothing to be done!
procedure Eval_Character_Literal (N : Node_Id) is
pragma Warnings (Off, N);
begin
null;
end Eval_Character_Literal;
---------------
-- Eval_Call --
---------------
-- Static function calls are either calls to predefined operators
-- with static arguments, or calls to functions that rename a literal.
-- Only the latter case is handled here, predefined operators are
-- constant-folded elsewhere.
-- If the function is itself inherited (see 7423-001) the literal of
-- the parent type must be explicitly converted to the return type
-- of the function.
procedure Eval_Call (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
Lit : Entity_Id;
begin
if Nkind (N) = N_Function_Call
and then No (Parameter_Associations (N))
and then Is_Entity_Name (Name (N))
and then Present (Alias (Entity (Name (N))))
and then Is_Enumeration_Type (Base_Type (Typ))
then
Lit := Ultimate_Alias (Entity (Name (N)));
if Ekind (Lit) = E_Enumeration_Literal then
if Base_Type (Etype (Lit)) /= Base_Type (Typ) then
Rewrite
(N, Convert_To (Typ, New_Occurrence_Of (Lit, Loc)));
else
Rewrite (N, New_Occurrence_Of (Lit, Loc));
end if;
Resolve (N, Typ);
end if;
end if;
end Eval_Call;
--------------------------
-- Eval_Case_Expression --
--------------------------
-- Right now we do not attempt folding of any case expressions, and the
-- language does not require it, so the only required processing is to
-- do the check for all expressions appearing in the case expression.
procedure Eval_Case_Expression (N : Node_Id) is
Alt : Node_Id;
begin
Check_Non_Static_Context (Expression (N));
Alt := First (Alternatives (N));
while Present (Alt) loop
Check_Non_Static_Context (Expression (Alt));
Next (Alt);
end loop;
end Eval_Case_Expression;
------------------------
-- Eval_Concatenation --
------------------------
-- Concatenation is a static function, so the result is static if both
-- operands are static (RM 4.9(7), 4.9(21)).
procedure Eval_Concatenation (N : Node_Id) is
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
C_Typ : constant Entity_Id := Root_Type (Component_Type (Etype (N)));
Stat : Boolean;
Fold : Boolean;
begin
-- Concatenation is never static in Ada 83, so if Ada 83 check operand
-- non-static context.
if Ada_Version = Ada_83
and then Comes_From_Source (N)
then
Check_Non_Static_Context (Left);
Check_Non_Static_Context (Right);
return;
end if;
-- If not foldable we are done. In principle concatenation that yields
-- any string type is static (i.e. an array type of character types).
-- However, character types can include enumeration literals, and
-- concatenation in that case cannot be described by a literal, so we
-- only consider the operation static if the result is an array of
-- (a descendant of) a predefined character type.
Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
if not (Is_Standard_Character_Type (C_Typ) and then Fold) then
Set_Is_Static_Expression (N, False);
return;
end if;
-- Compile time string concatenation
-- ??? Note that operands that are aggregates can be marked as static,
-- so we should attempt at a later stage to fold concatenations with
-- such aggregates.
declare
Left_Str : constant Node_Id := Get_String_Val (Left);
Left_Len : Nat;
Right_Str : constant Node_Id := Get_String_Val (Right);
Folded_Val : String_Id;
begin
-- Establish new string literal, and store left operand. We make
-- sure to use the special Start_String that takes an operand if
-- the left operand is a string literal. Since this is optimized
-- in the case where that is the most recently created string
-- literal, we ensure efficient time/space behavior for the
-- case of a concatenation of a series of string literals.
if Nkind (Left_Str) = N_String_Literal then
Left_Len := String_Length (Strval (Left_Str));
-- If the left operand is the empty string, and the right operand
-- is a string literal (the case of "" & "..."), the result is the
-- value of the right operand. This optimization is important when
-- Is_Folded_In_Parser, to avoid copying an enormous right
-- operand.
if Left_Len = 0 and then Nkind (Right_Str) = N_String_Literal then
Folded_Val := Strval (Right_Str);
else
Start_String (Strval (Left_Str));
end if;
else
Start_String;
Store_String_Char (UI_To_CC (Char_Literal_Value (Left_Str)));
Left_Len := 1;
end if;
-- Now append the characters of the right operand, unless we
-- optimized the "" & "..." case above.
if Nkind (Right_Str) = N_String_Literal then
if Left_Len /= 0 then
Store_String_Chars (Strval (Right_Str));
Folded_Val := End_String;
end if;
else
Store_String_Char (UI_To_CC (Char_Literal_Value (Right_Str)));
Folded_Val := End_String;
end if;
Set_Is_Static_Expression (N, Stat);
if Stat then
-- If left operand is the empty string, the result is the
-- right operand, including its bounds if anomalous.
if Left_Len = 0
and then Is_Array_Type (Etype (Right))
and then Etype (Right) /= Any_String
then
Set_Etype (N, Etype (Right));
end if;
Fold_Str (N, Folded_Val, Static => True);
end if;
end;
end Eval_Concatenation;
---------------------------------
-- Eval_Conditional_Expression --
---------------------------------
-- We can fold to a static expression if the condition and both constituent
-- expressions are static. Otherwise, the only required processing is to do
-- the check for non-static context for the then and else expressions.
procedure Eval_Conditional_Expression (N : Node_Id) is
Condition : constant Node_Id := First (Expressions (N));
Then_Expr : constant Node_Id := Next (Condition);
Else_Expr : constant Node_Id := Next (Then_Expr);
Result : Node_Id;
Non_Result : Node_Id;
Rstat : constant Boolean :=
Is_Static_Expression (Condition)
and then
Is_Static_Expression (Then_Expr)
and then
Is_Static_Expression (Else_Expr);
begin
-- If any operand is Any_Type, just propagate to result and do not try
-- to fold, this prevents cascaded errors.
if Etype (Condition) = Any_Type or else
Etype (Then_Expr) = Any_Type or else
Etype (Else_Expr) = Any_Type
then
Set_Etype (N, Any_Type);
Set_Is_Static_Expression (N, False);
return;
-- Static case where we can fold. Note that we don't try to fold cases
-- where the condition is known at compile time, but the result is
-- non-static. This avoids possible cases of infinite recursion where
-- the expander puts in a redundant test and we remove it. Instead we
-- deal with these cases in the expander.
elsif Rstat then
-- Select result operand
if Is_True (Expr_Value (Condition)) then
Result := Then_Expr;
Non_Result := Else_Expr;
else
Result := Else_Expr;
Non_Result := Then_Expr;
end if;
-- Note that it does not matter if the non-result operand raises a
-- Constraint_Error, but if the result raises constraint error then
-- we replace the node with a raise constraint error. This will
-- properly propagate Raises_Constraint_Error since this flag is
-- set in Result.
if Raises_Constraint_Error (Result) then
Rewrite_In_Raise_CE (N, Result);
Check_Non_Static_Context (Non_Result);
-- Otherwise the result operand replaces the original node
else
Rewrite (N, Relocate_Node (Result));
end if;
-- Case of condition not known at compile time
else
Check_Non_Static_Context (Condition);
Check_Non_Static_Context (Then_Expr);
Check_Non_Static_Context (Else_Expr);
end if;
Set_Is_Static_Expression (N, Rstat);
end Eval_Conditional_Expression;
----------------------
-- Eval_Entity_Name --
----------------------
-- This procedure is used for identifiers and expanded names other than
-- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
-- static if they denote a static constant (RM 4.9(6)) or if the name
-- denotes an enumeration literal (RM 4.9(22)).
procedure Eval_Entity_Name (N : Node_Id) is
Def_Id : constant Entity_Id := Entity (N);
Val : Node_Id;
begin
-- Enumeration literals are always considered to be constants
-- and cannot raise constraint error (RM 4.9(22)).
if Ekind (Def_Id) = E_Enumeration_Literal then
Set_Is_Static_Expression (N);
return;
-- A name is static if it denotes a static constant (RM 4.9(5)), and
-- we also copy Raise_Constraint_Error. Notice that even if non-static,
-- it does not violate 10.2.1(8) here, since this is not a variable.
elsif Ekind (Def_Id) = E_Constant then
-- Deferred constants must always be treated as nonstatic
-- outside the scope of their full view.
if Present (Full_View (Def_Id))
and then not In_Open_Scopes (Scope (Def_Id))
then
Val := Empty;
else
Val := Constant_Value (Def_Id);
end if;
if Present (Val) then
Set_Is_Static_Expression
(N, Is_Static_Expression (Val)
and then Is_Static_Subtype (Etype (Def_Id)));
Set_Raises_Constraint_Error (N, Raises_Constraint_Error (Val));
if not Is_Static_Expression (N)
and then not Is_Generic_Type (Etype (N))
then
Validate_Static_Object_Name (N);
end if;
return;
end if;
end if;
-- Fall through if the name is not static
Validate_Static_Object_Name (N);
end Eval_Entity_Name;
----------------------------
-- Eval_Indexed_Component --
----------------------------
-- Indexed components are never static, so we need to perform the check
-- for non-static context on the index values. Then, we check if the
-- value can be obtained at compile time, even though it is non-static.
procedure Eval_Indexed_Component (N : Node_Id) is
Expr : Node_Id;
begin
-- Check for non-static context on index values
Expr := First (Expressions (N));
while Present (Expr) loop
Check_Non_Static_Context (Expr);
Next (Expr);
end loop;
-- If the indexed component appears in an object renaming declaration
-- then we do not want to try to evaluate it, since in this case we
-- need the identity of the array element.
if Nkind (Parent (N)) = N_Object_Renaming_Declaration then
return;
-- Similarly if the indexed component appears as the prefix of an
-- attribute we don't want to evaluate it, because at least for
-- some cases of attributes we need the identify (e.g. Access, Size)
elsif Nkind (Parent (N)) = N_Attribute_Reference then
return;
end if;
-- Note: there are other cases, such as the left side of an assignment,
-- or an OUT parameter for a call, where the replacement results in the
-- illegal use of a constant, But these cases are illegal in the first
-- place, so the replacement, though silly, is harmless.
-- Now see if this is a constant array reference
if List_Length (Expressions (N)) = 1
and then Is_Entity_Name (Prefix (N))
and then Ekind (Entity (Prefix (N))) = E_Constant
and then Present (Constant_Value (Entity (Prefix (N))))
then
declare
Loc : constant Source_Ptr := Sloc (N);
Arr : constant Node_Id := Constant_Value (Entity (Prefix (N)));
Sub : constant Node_Id := First (Expressions (N));
Atyp : Entity_Id;
-- Type of array
Lin : Nat;
-- Linear one's origin subscript value for array reference
Lbd : Node_Id;
-- Lower bound of the first array index
Elm : Node_Id;
-- Value from constant array
begin
Atyp := Etype (Arr);
if Is_Access_Type (Atyp) then
Atyp := Designated_Type (Atyp);
end if;
-- If we have an array type (we should have but perhaps there are
-- error cases where this is not the case), then see if we can do
-- a constant evaluation of the array reference.
if Is_Array_Type (Atyp) and then Atyp /= Any_Composite then
if Ekind (Atyp) = E_String_Literal_Subtype then
Lbd := String_Literal_Low_Bound (Atyp);
else
Lbd := Type_Low_Bound (Etype (First_Index (Atyp)));
end if;
if Compile_Time_Known_Value (Sub)
and then Nkind (Arr) = N_Aggregate
and then Compile_Time_Known_Value (Lbd)
and then Is_Discrete_Type (Component_Type (Atyp))
then
Lin := UI_To_Int (Expr_Value (Sub) - Expr_Value (Lbd)) + 1;
if List_Length (Expressions (Arr)) >= Lin then
Elm := Pick (Expressions (Arr), Lin);
-- If the resulting expression is compile time known,
-- then we can rewrite the indexed component with this
-- value, being sure to mark the result as non-static.
-- We also reset the Sloc, in case this generates an
-- error later on (e.g. 136'Access).
if Compile_Time_Known_Value (Elm) then
Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
Set_Is_Static_Expression (N, False);
Set_Sloc (N, Loc);
end if;
end if;
-- We can also constant-fold if the prefix is a string literal.
-- This will be useful in an instantiation or an inlining.
elsif Compile_Time_Known_Value (Sub)
and then Nkind (Arr) = N_String_Literal
and then Compile_Time_Known_Value (Lbd)
and then Expr_Value (Lbd) = 1
and then Expr_Value (Sub) <=
String_Literal_Length (Etype (Arr))
then
declare
C : constant Char_Code :=
Get_String_Char (Strval (Arr),
UI_To_Int (Expr_Value (Sub)));
begin
Set_Character_Literal_Name (C);
Elm :=
Make_Character_Literal (Loc,
Chars => Name_Find,
Char_Literal_Value => UI_From_CC (C));
Set_Etype (Elm, Component_Type (Atyp));
Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
Set_Is_Static_Expression (N, False);
end;
end if;
end if;
end;
end if;
end Eval_Indexed_Component;
--------------------------
-- Eval_Integer_Literal --
--------------------------
-- Numeric literals are static (RM 4.9(1)), and have already been marked
-- as static by the analyzer. The reason we did it that early is to allow
-- the possibility of turning off the Is_Static_Expression flag after
-- analysis, but before resolution, when integer literals are generated in
-- the expander that do not correspond to static expressions.
procedure Eval_Integer_Literal (N : Node_Id) is
T : constant Entity_Id := Etype (N);
function In_Any_Integer_Context return Boolean;
-- If the literal is resolved with a specific type in a context where
-- the expected type is Any_Integer, there are no range checks on the
-- literal. By the time the literal is evaluated, it carries the type
-- imposed by the enclosing expression, and we must recover the context
-- to determine that Any_Integer is meant.
----------------------------
-- In_Any_Integer_Context --
----------------------------
function In_Any_Integer_Context return Boolean is
Par : constant Node_Id := Parent (N);
K : constant Node_Kind := Nkind (Par);
begin
-- Any_Integer also appears in digits specifications for real types,
-- but those have bounds smaller that those of any integer base type,
-- so we can safely ignore these cases.
return K = N_Number_Declaration
or else K = N_Attribute_Reference
or else K = N_Attribute_Definition_Clause
or else K = N_Modular_Type_Definition
or else K = N_Signed_Integer_Type_Definition;
end In_Any_Integer_Context;
-- Start of processing for Eval_Integer_Literal
begin
-- If the literal appears in a non-expression context, then it is
-- certainly appearing in a non-static context, so check it. This is
-- actually a redundant check, since Check_Non_Static_Context would
-- check it, but it seems worth while avoiding the call.
if Nkind (Parent (N)) not in N_Subexpr
and then not In_Any_Integer_Context
then
Check_Non_Static_Context (N);
end if;
-- Modular integer literals must be in their base range
if Is_Modular_Integer_Type (T)
and then Is_Out_Of_Range (N, Base_Type (T), Assume_Valid => True)
then
Out_Of_Range (N);
end if;
end Eval_Integer_Literal;
---------------------
-- Eval_Logical_Op --
---------------------
-- Logical operations are static functions, so the result is potentially
-- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
procedure Eval_Logical_Op (N : Node_Id) is
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
Stat : Boolean;
Fold : Boolean;
begin
-- If not foldable we are done
Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
if not Fold then
return;
end if;
-- Compile time evaluation of logical operation
declare
Left_Int : constant Uint := Expr_Value (Left);
Right_Int : constant Uint := Expr_Value (Right);
begin
-- VMS includes bitwise operations on signed types
if Is_Modular_Integer_Type (Etype (N))
or else Is_VMS_Operator (Entity (N))
then
declare
Left_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
Right_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
begin
To_Bits (Left_Int, Left_Bits);
To_Bits (Right_Int, Right_Bits);
-- Note: should really be able to use array ops instead of
-- these loops, but they weren't working at the time ???
if Nkind (N) = N_Op_And then
for J in Left_Bits'Range loop
Left_Bits (J) := Left_Bits (J) and Right_Bits (J);
end loop;
elsif Nkind (N) = N_Op_Or then
for J in Left_Bits'Range loop
Left_Bits (J) := Left_Bits (J) or Right_Bits (J);
end loop;
else
pragma Assert (Nkind (N) = N_Op_Xor);
for J in Left_Bits'Range loop
Left_Bits (J) := Left_Bits (J) xor Right_Bits (J);
end loop;
end if;
Fold_Uint (N, From_Bits (Left_Bits, Etype (N)), Stat);
end;
else
pragma Assert (Is_Boolean_Type (Etype (N)));
if Nkind (N) = N_Op_And then
Fold_Uint (N,
Test (Is_True (Left_Int) and then Is_True (Right_Int)), Stat);
elsif Nkind (N) = N_Op_Or then
Fold_Uint (N,
Test (Is_True (Left_Int) or else Is_True (Right_Int)), Stat);
else
pragma Assert (Nkind (N) = N_Op_Xor);
Fold_Uint (N,
Test (Is_True (Left_Int) xor Is_True (Right_Int)), Stat);
end if;
end if;
end;
end Eval_Logical_Op;
------------------------
-- Eval_Membership_Op --
------------------------
-- A membership test is potentially static if the expression is static, and
-- the range is a potentially static range, or is a subtype mark denoting a
-- static subtype (RM 4.9(12)).
procedure Eval_Membership_Op (N : Node_Id) is
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
Def_Id : Entity_Id;
Lo : Node_Id;
Hi : Node_Id;
Result : Boolean;
Stat : Boolean;
Fold : Boolean;
begin
-- Ignore if error in either operand, except to make sure that Any_Type
-- is properly propagated to avoid junk cascaded errors.
if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
Set_Etype (N, Any_Type);
return;
end if;
-- Ignore if types involved have predicates
if Present (Predicate_Function (Etype (Left)))
or else
Present (Predicate_Function (Etype (Right)))
then
return;
end if;
-- Case of right operand is a subtype name
if Is_Entity_Name (Right) then
Def_Id := Entity (Right);
if (Is_Scalar_Type (Def_Id) or else Is_String_Type (Def_Id))
and then Is_OK_Static_Subtype (Def_Id)
then
Test_Expression_Is_Foldable (N, Left, Stat, Fold);
if not Fold or else not Stat then
return;
end if;
else
Check_Non_Static_Context (Left);
return;
end if;
-- For string membership tests we will check the length further on
if not Is_String_Type (Def_Id) then
Lo := Type_Low_Bound (Def_Id);
Hi := Type_High_Bound (Def_Id);
else
Lo := Empty;
Hi := Empty;
end if;
-- Case of right operand is a range
else
if Is_Static_Range (Right) then
Test_Expression_Is_Foldable (N, Left, Stat, Fold);
if not Fold or else not Stat then
return;
-- If one bound of range raises CE, then don't try to fold
elsif not Is_OK_Static_Range (Right) then
Check_Non_Static_Context (Left);
return;
end if;
else
Check_Non_Static_Context (Left);
return;
end if;
-- Here we know range is an OK static range
Lo := Low_Bound (Right);
Hi := High_Bound (Right);
end if;
-- For strings we check that the length of the string expression is
-- compatible with the string subtype if the subtype is constrained,
-- or if unconstrained then the test is always true.
if Is_String_Type (Etype (Right)) then
if not Is_Constrained (Etype (Right)) then
Result := True;
else
declare
Typlen : constant Uint := String_Type_Len (Etype (Right));
Strlen : constant Uint :=
UI_From_Int
(String_Length (Strval (Get_String_Val (Left))));
begin
Result := (Typlen = Strlen);
end;
end if;
-- Fold the membership test. We know we have a static range and Lo and
-- Hi are set to the expressions for the end points of this range.
elsif Is_Real_Type (Etype (Right)) then
declare
Leftval : constant Ureal := Expr_Value_R (Left);
begin
Result := Expr_Value_R (Lo) <= Leftval
and then Leftval <= Expr_Value_R (Hi);
end;
else
declare
Leftval : constant Uint := Expr_Value (Left);
begin
Result := Expr_Value (Lo) <= Leftval
and then Leftval <= Expr_Value (Hi);
end;
end if;
if Nkind (N) = N_Not_In then
Result := not Result;
end if;
Fold_Uint (N, Test (Result), True);
Warn_On_Known_Condition (N);
end Eval_Membership_Op;
------------------------
-- Eval_Named_Integer --
------------------------
procedure Eval_Named_Integer (N : Node_Id) is
begin
Fold_Uint (N,
Expr_Value (Expression (Declaration_Node (Entity (N)))), True);
end Eval_Named_Integer;
---------------------
-- Eval_Named_Real --
---------------------
procedure Eval_Named_Real (N : Node_Id) is
begin
Fold_Ureal (N,
Expr_Value_R (Expression (Declaration_Node (Entity (N)))), True);
end Eval_Named_Real;
-------------------
-- Eval_Op_Expon --
-------------------
-- Exponentiation is a static functions, so the result is potentially
-- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
procedure Eval_Op_Expon (N : Node_Id) is
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
Stat : Boolean;
Fold : Boolean;
begin
-- If not foldable we are done
Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
if not Fold then
return;
end if;
-- Fold exponentiation operation
declare
Right_Int : constant Uint := Expr_Value (Right);
begin
-- Integer case
if Is_Integer_Type (Etype (Left)) then
declare
Left_Int : constant Uint := Expr_Value (Left);
Result : Uint;
begin
-- Exponentiation of an integer raises Constraint_Error for a
-- negative exponent (RM 4.5.6).
if Right_Int < 0 then
Apply_Compile_Time_Constraint_Error
(N, "integer exponent negative",
CE_Range_Check_Failed,
Warn => not Stat);
return;
else
if OK_Bits (N, Num_Bits (Left_Int) * Right_Int) then
Result := Left_Int ** Right_Int;
else
Result := Left_Int;
end if;
if Is_Modular_Integer_Type (Etype (N)) then
Result := Result mod Modulus (Etype (N));
end if;
Fold_Uint (N, Result, Stat);
end if;
end;
-- Real case
else
declare
Left_Real : constant Ureal := Expr_Value_R (Left);
begin
-- Cannot have a zero base with a negative exponent
if UR_Is_Zero (Left_Real) then
if Right_Int < 0 then
Apply_Compile_Time_Constraint_Error
(N, "zero ** negative integer",
CE_Range_Check_Failed,
Warn => not Stat);
return;
else
Fold_Ureal (N, Ureal_0, Stat);
end if;
else
Fold_Ureal (N, Left_Real ** Right_Int, Stat);
end if;
end;
end if;
end;
end Eval_Op_Expon;
-----------------
-- Eval_Op_Not --
-----------------
-- The not operation is a static functions, so the result is potentially
-- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
procedure Eval_Op_Not (N : Node_Id) is
Right : constant Node_Id := Right_Opnd (N);
Stat : Boolean;
Fold : Boolean;
begin
-- If not foldable we are done
Test_Expression_Is_Foldable (N, Right, Stat, Fold);
if not Fold then
return;
end if;
-- Fold not operation
declare
Rint : constant Uint := Expr_Value (Right);
Typ : constant Entity_Id := Etype (N);
begin
-- Negation is equivalent to subtracting from the modulus minus one.
-- For a binary modulus this is equivalent to the ones-complement of
-- the original value. For non-binary modulus this is an arbitrary
-- but consistent definition.
if Is_Modular_Integer_Type (Typ) then
Fold_Uint (N, Modulus (Typ) - 1 - Rint, Stat);
else
pragma Assert (Is_Boolean_Type (Typ));
Fold_Uint (N, Test (not Is_True (Rint)), Stat);
end if;
Set_Is_Static_Expression (N, Stat);
end;
end Eval_Op_Not;
-------------------------------
-- Eval_Qualified_Expression --
-------------------------------
-- A qualified expression is potentially static if its subtype mark denotes
-- a static subtype and its expression is potentially static (RM 4.9 (11)).
procedure Eval_Qualified_Expression (N : Node_Id) is
Operand : constant Node_Id := Expression (N);
Target_Type : constant Entity_Id := Entity (Subtype_Mark (N));
Stat : Boolean;
Fold : Boolean;
Hex : Boolean;
begin
-- Can only fold if target is string or scalar and subtype is static.
-- Also, do not fold if our parent is an allocator (this is because the
-- qualified expression is really part of the syntactic structure of an
-- allocator, and we do not want to end up with something that
-- corresponds to "new 1" where the 1 is the result of folding a
-- qualified expression).
if not Is_Static_Subtype (Target_Type)
or else Nkind (Parent (N)) = N_Allocator
then
Check_Non_Static_Context (Operand);
-- If operand is known to raise constraint_error, set the flag on the
-- expression so it does not get optimized away.
if Nkind (Operand) = N_Raise_Constraint_Error then
Set_Raises_Constraint_Error (N);
end if;
return;
end if;
-- If not foldable we are done
Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
if not Fold then
return;
-- Don't try fold if target type has constraint error bounds
elsif not Is_OK_Static_Subtype (Target_Type) then
Set_Raises_Constraint_Error (N);
return;
end if;
-- Here we will fold, save Print_In_Hex indication
Hex := Nkind (Operand) = N_Integer_Literal
and then Print_In_Hex (Operand);
-- Fold the result of qualification
if Is_Discrete_Type (Target_Type) then
Fold_Uint (N, Expr_Value (Operand), Stat);
-- Preserve Print_In_Hex indication
if Hex and then Nkind (N) = N_Integer_Literal then
Set_Print_In_Hex (N);
end if;
elsif Is_Real_Type (Target_Type) then
Fold_Ureal (N, Expr_Value_R (Operand), Stat);
else
Fold_Str (N, Strval (Get_String_Val (Operand)), Stat);
if not Stat then
Set_Is_Static_Expression (N, False);
else
Check_String_Literal_Length (N, Target_Type);
end if;
return;
end if;
-- The expression may be foldable but not static
Set_Is_Static_Expression (N, Stat);
if Is_Out_Of_Range (N, Etype (N), Assume_Valid => True) then
Out_Of_Range (N);
end if;
end Eval_Qualified_Expression;
-----------------------
-- Eval_Real_Literal --
-----------------------
-- Numeric literals are static (RM 4.9(1)), and have already been marked
-- as static by the analyzer. The reason we did it that early is to allow
-- the possibility of turning off the Is_Static_Expression flag after
-- analysis, but before resolution, when integer literals are generated
-- in the expander that do not correspond to static expressions.
procedure Eval_Real_Literal (N : Node_Id) is
PK : constant Node_Kind := Nkind (Parent (N));
begin
-- If the literal appears in a non-expression context and not as part of
-- a number declaration, then it is appearing in a non-static context,
-- so check it.
if PK not in N_Subexpr and then PK /= N_Number_Declaration then
Check_Non_Static_Context (N);
end if;
end Eval_Real_Literal;
------------------------
-- Eval_Relational_Op --
------------------------
-- Relational operations are static functions, so the result is static if
-- both operands are static (RM 4.9(7), 4.9(20)), except that for strings,
-- the result is never static, even if the operands are.
procedure Eval_Relational_Op (N : Node_Id) is
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
Typ : constant Entity_Id := Etype (Left);
Otype : Entity_Id := Empty;
Result : Boolean;
Stat : Boolean;
Fold : Boolean;
begin
-- One special case to deal with first. If we can tell that the result
-- will be false because the lengths of one or more index subtypes are
-- compile time known and different, then we can replace the entire
-- result by False. We only do this for one dimensional arrays, because
-- the case of multi-dimensional arrays is rare and too much trouble! If
-- one of the operands is an illegal aggregate, its type might still be
-- an arbitrary composite type, so nothing to do.
if Is_Array_Type (Typ)
and then Typ /= Any_Composite
and then Number_Dimensions (Typ) = 1
and then (Nkind (N) = N_Op_Eq or else Nkind (N) = N_Op_Ne)
then
if Raises_Constraint_Error (Left)
or else Raises_Constraint_Error (Right)
then
return;
end if;
-- OK, we have the case where we may be able to do this fold
Length_Mismatch : declare
procedure Get_Static_Length (Op : Node_Id; Len : out Uint);
-- If Op is an expression for a constrained array with a known at
-- compile time length, then Len is set to this (non-negative
-- length). Otherwise Len is set to minus 1.
-----------------------
-- Get_Static_Length --
-----------------------
procedure Get_Static_Length (Op : Node_Id; Len : out Uint) is
T : Entity_Id;
begin
-- First easy case string literal
if Nkind (Op) = N_String_Literal then
Len := UI_From_Int (String_Length (Strval (Op)));
return;
end if;
-- Second easy case, not constrained subtype, so no length
if not Is_Constrained (Etype (Op)) then
Len := Uint_Minus_1;
return;
end if;
-- General case
T := Etype (First_Index (Etype (Op)));
-- The simple case, both bounds are known at compile time
if Is_Discrete_Type (T)
and then
Compile_Time_Known_Value (Type_Low_Bound (T))
and then
Compile_Time_Known_Value (Type_High_Bound (T))
then
Len := UI_Max (Uint_0,
Expr_Value (Type_High_Bound (T)) -
Expr_Value (Type_Low_Bound (T)) + 1);
return;
end if;
-- A more complex case, where the bounds are of the form
-- X [+/- K1] .. X [+/- K2]), where X is an expression that is
-- either A'First or A'Last (with A an entity name), or X is an
-- entity name, and the two X's are the same and K1 and K2 are
-- known at compile time, in this case, the length can also be
-- computed at compile time, even though the bounds are not
-- known. A common case of this is e.g. (X'First .. X'First+5).
Extract_Length : declare
procedure Decompose_Expr
(Expr : Node_Id;
Ent : out Entity_Id;
Kind : out Character;
Cons : out Uint);
-- Given an expression, see if is of the form above,
-- X [+/- K]. If so Ent is set to the entity in X,
-- Kind is 'F','L','E' for 'First/'Last/simple entity,
-- and Cons is the value of K. If the expression is
-- not of the required form, Ent is set to Empty.
--------------------
-- Decompose_Expr --
--------------------
procedure Decompose_Expr
(Expr : Node_Id;
Ent : out Entity_Id;
Kind : out Character;
Cons : out Uint)
is
Exp : Node_Id;
begin
if Nkind (Expr) = N_Op_Add
and then Compile_Time_Known_Value (Right_Opnd (Expr))
then
Exp := Left_Opnd (Expr);
Cons := Expr_Value (Right_Opnd (Expr));
elsif Nkind (Expr) = N_Op_Subtract
and then Compile_Time_Known_Value (Right_Opnd (Expr))
then
Exp := Left_Opnd (Expr);
Cons := -Expr_Value (Right_Opnd (Expr));
-- If the bound is a constant created to remove side
-- effects, recover original expression to see if it has
-- one of the recognizable forms.
elsif Nkind (Expr) = N_Identifier
and then not Comes_From_Source (Entity (Expr))
and then Ekind (Entity (Expr)) = E_Constant
and then
Nkind (Parent (Entity (Expr))) = N_Object_Declaration
then
Exp := Expression (Parent (Entity (Expr)));
Decompose_Expr (Exp, Ent, Kind, Cons);
-- If original expression includes an entity, create a
-- reference to it for use below.
if Present (Ent) then
Exp := New_Occurrence_Of (Ent, Sloc (Ent));
end if;
else
Exp := Expr;
Cons := Uint_0;
end if;
-- At this stage Exp is set to the potential X
if Nkind (Exp) = N_Attribute_Reference then
if Attribute_Name (Exp) = Name_First then
Kind := 'F';
elsif Attribute_Name (Exp) = Name_Last then
Kind := 'L';
else
Ent := Empty;
return;
end if;
Exp := Prefix (Exp);
else
Kind := 'E';
end if;
if Is_Entity_Name (Exp)
and then Present (Entity (Exp))
then
Ent := Entity (Exp);
else
Ent := Empty;
end if;
end Decompose_Expr;
-- Local Variables
Ent1, Ent2 : Entity_Id;
Kind1, Kind2 : Character;
Cons1, Cons2 : Uint;
-- Start of processing for Extract_Length
begin
Decompose_Expr
(Original_Node (Type_Low_Bound (T)), Ent1, Kind1, Cons1);
Decompose_Expr
(Original_Node (Type_High_Bound (T)), Ent2, Kind2, Cons2);
if Present (Ent1)
and then Kind1 = Kind2
and then Ent1 = Ent2
then
Len := Cons2 - Cons1 + 1;
else
Len := Uint_Minus_1;
end if;
end Extract_Length;
end Get_Static_Length;
-- Local Variables
Len_L : Uint;
Len_R : Uint;
-- Start of processing for Length_Mismatch
begin
Get_Static_Length (Left, Len_L);
Get_Static_Length (Right, Len_R);
if Len_L /= Uint_Minus_1
and then Len_R /= Uint_Minus_1
and then Len_L /= Len_R
then
Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
Warn_On_Known_Condition (N);
return;
end if;
end Length_Mismatch;
end if;
-- Test for expression being foldable
Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
-- Only comparisons of scalars can give static results. In particular,
-- comparisons of strings never yield a static result, even if both
-- operands are static strings.
if not Is_Scalar_Type (Typ) then
Stat := False;
Set_Is_Static_Expression (N, False);
end if;
-- For operators on universal numeric types called as functions with
-- an explicit scope, determine appropriate specific numeric type, and
-- diagnose possible ambiguity.
if Is_Universal_Numeric_Type (Etype (Left))
and then
Is_Universal_Numeric_Type (Etype (Right))
then
Otype := Find_Universal_Operator_Type (N);
end if;
-- For static real type expressions, we cannot use Compile_Time_Compare
-- since it worries about run-time results which are not exact.
if Stat and then Is_Real_Type (Typ) then
declare
Left_Real : constant Ureal := Expr_Value_R (Left);
Right_Real : constant Ureal := Expr_Value_R (Right);
begin
case Nkind (N) is
when N_Op_Eq => Result := (Left_Real = Right_Real);
when N_Op_Ne => Result := (Left_Real /= Right_Real);
when N_Op_Lt => Result := (Left_Real < Right_Real);
when N_Op_Le => Result := (Left_Real <= Right_Real);
when N_Op_Gt => Result := (Left_Real > Right_Real);
when N_Op_Ge => Result := (Left_Real >= Right_Real);
when others =>
raise Program_Error;
end case;
Fold_Uint (N, Test (Result), True);
end;
-- For all other cases, we use Compile_Time_Compare to do the compare
else
declare
CR : constant Compare_Result :=
Compile_Time_Compare (Left, Right, Assume_Valid => False);
begin
if CR = Unknown then
return;
end if;
case Nkind (N) is
when N_Op_Eq =>
if CR = EQ then
Result := True;
elsif CR = NE or else CR = GT or else CR = LT then
Result := False;
else
return;
end if;
when N_Op_Ne =>
if CR = NE or else CR = GT or else CR = LT then
Result := True;
elsif CR = EQ then
Result := False;
else
return;
end if;
when N_Op_Lt =>
if CR = LT then
Result := True;
elsif CR = EQ or else CR = GT or else CR = GE then
Result := False;
else
return;
end if;
when N_Op_Le =>
if CR = LT or else CR = EQ or else CR = LE then
Result := True;
elsif CR = GT then
Result := False;
else
return;
end if;
when N_Op_Gt =>
if CR = GT then
Result := True;
elsif CR = EQ or else CR = LT or else CR = LE then
Result := False;
else
return;
end if;
when N_Op_Ge =>
if CR = GT or else CR = EQ or else CR = GE then
Result := True;
elsif CR = LT then
Result := False;
else
return;
end if;
when others =>
raise Program_Error;
end case;
end;
Fold_Uint (N, Test (Result), Stat);
end if;
-- For the case of a folded relational operator on a specific numeric
-- type, freeze operand type now.
if Present (Otype) then
Freeze_Before (N, Otype);
end if;
Warn_On_Known_Condition (N);
end Eval_Relational_Op;
----------------
-- Eval_Shift --
----------------
-- Shift operations are intrinsic operations that can never be static, so
-- the only processing required is to perform the required check for a non
-- static context for the two operands.
-- Actually we could do some compile time evaluation here some time ???
procedure Eval_Shift (N : Node_Id) is
begin
Check_Non_Static_Context (Left_Opnd (N));
Check_Non_Static_Context (Right_Opnd (N));
end Eval_Shift;
------------------------
-- Eval_Short_Circuit --
------------------------
-- A short circuit operation is potentially static if both operands are
-- potentially static (RM 4.9 (13)).
procedure Eval_Short_Circuit (N : Node_Id) is
Kind : constant Node_Kind := Nkind (N);
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
Left_Int : Uint;
Rstat : constant Boolean :=
Is_Static_Expression (Left)
and then
Is_Static_Expression (Right);
begin
-- Short circuit operations are never static in Ada 83
if Ada_Version = Ada_83 and then Comes_From_Source (N) then
Check_Non_Static_Context (Left);
Check_Non_Static_Context (Right);
return;
end if;
-- Now look at the operands, we can't quite use the normal call to
-- Test_Expression_Is_Foldable here because short circuit operations
-- are a special case, they can still be foldable, even if the right
-- operand raises constraint error.
-- If either operand is Any_Type, just propagate to result and do not
-- try to fold, this prevents cascaded errors.
if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
Set_Etype (N, Any_Type);
return;
-- If left operand raises constraint error, then replace node N with
-- the raise constraint error node, and we are obviously not foldable.
-- Is_Static_Expression is set from the two operands in the normal way,
-- and we check the right operand if it is in a non-static context.
elsif Raises_Constraint_Error (Left) then
if not Rstat then
Check_Non_Static_Context (Right);
end if;
Rewrite_In_Raise_CE (N, Left);
Set_Is_Static_Expression (N, Rstat);
return;
-- If the result is not static, then we won't in any case fold
elsif not Rstat then
Check_Non_Static_Context (Left);
Check_Non_Static_Context (Right);
return;
end if;
-- Here the result is static, note that, unlike the normal processing
-- in Test_Expression_Is_Foldable, we did *not* check above to see if
-- the right operand raises constraint error, that's because it is not
-- significant if the left operand is decisive.
Set_Is_Static_Expression (N);
-- It does not matter if the right operand raises constraint error if
-- it will not be evaluated. So deal specially with the cases where
-- the right operand is not evaluated. Note that we will fold these
-- cases even if the right operand is non-static, which is fine, but
-- of course in these cases the result is not potentially static.
Left_Int := Expr_Value (Left);
if (Kind = N_And_Then and then Is_False (Left_Int))
or else
(Kind = N_Or_Else and then Is_True (Left_Int))
then
Fold_Uint (N, Left_Int, Rstat);
return;
end if;
-- If first operand not decisive, then it does matter if the right
-- operand raises constraint error, since it will be evaluated, so
-- we simply replace the node with the right operand. Note that this
-- properly propagates Is_Static_Expression and Raises_Constraint_Error
-- (both are set to True in Right).
if Raises_Constraint_Error (Right) then
Rewrite_In_Raise_CE (N, Right);
Check_Non_Static_Context (Left);
return;
end if;
-- Otherwise the result depends on the right operand
Fold_Uint (N, Expr_Value (Right), Rstat);
return;
end Eval_Short_Circuit;
----------------
-- Eval_Slice --
----------------
-- Slices can never be static, so the only processing required is to check
-- for non-static context if an explicit range is given.
procedure Eval_Slice (N : Node_Id) is
Drange : constant Node_Id := Discrete_Range (N);
begin
if Nkind (Drange) = N_Range then
Check_Non_Static_Context (Low_Bound (Drange));
Check_Non_Static_Context (High_Bound (Drange));
end if;
-- A slice of the form A (subtype), when the subtype is the index of
-- the type of A, is redundant, the slice can be replaced with A, and
-- this is worth a warning.
if Is_Entity_Name (Prefix (N)) then
declare
E : constant Entity_Id := Entity (Prefix (N));
T : constant Entity_Id := Etype (E);
begin
if Ekind (E) = E_Constant
and then Is_Array_Type (T)
and then Is_Entity_Name (Drange)
then
if Is_Entity_Name (Original_Node (First_Index (T)))
and then Entity (Original_Node (First_Index (T)))
= Entity (Drange)
then
if Warn_On_Redundant_Constructs then
Error_Msg_N ("redundant slice denotes whole array?", N);
end if;
-- The following might be a useful optimization????
-- Rewrite (N, New_Occurrence_Of (E, Sloc (N)));
end if;
end if;
end;
end if;
end Eval_Slice;
-------------------------
-- Eval_String_Literal --
-------------------------
procedure Eval_String_Literal (N : Node_Id) is
Typ : constant Entity_Id := Etype (N);
Bas : constant Entity_Id := Base_Type (Typ);
Xtp : Entity_Id;
Len : Nat;
Lo : Node_Id;
begin
-- Nothing to do if error type (handles cases like default expressions
-- or generics where we have not yet fully resolved the type).
if Bas = Any_Type or else Bas = Any_String then
return;
end if;
-- String literals are static if the subtype is static (RM 4.9(2)), so
-- reset the static expression flag (it was set unconditionally in
-- Analyze_String_Literal) if the subtype is non-static. We tell if
-- the subtype is static by looking at the lower bound.
if Ekind (Typ) = E_String_Literal_Subtype then
if not Is_OK_Static_Expression (String_Literal_Low_Bound (Typ)) then
Set_Is_Static_Expression (N, False);
return;
end if;
-- Here if Etype of string literal is normal Etype (not yet possible,
-- but may be possible in future).
elsif not Is_OK_Static_Expression
(Type_Low_Bound (Etype (First_Index (Typ))))
then
Set_Is_Static_Expression (N, False);
return;
end if;
-- If original node was a type conversion, then result if non-static
if Nkind (Original_Node (N)) = N_Type_Conversion then
Set_Is_Static_Expression (N, False);
return;
end if;
-- Test for illegal Ada 95 cases. A string literal is illegal in Ada 95
-- if its bounds are outside the index base type and this index type is
-- static. This can happen in only two ways. Either the string literal
-- is too long, or it is null, and the lower bound is type'First. In
-- either case it is the upper bound that is out of range of the index
-- type.
if Ada_Version >= Ada_95 then
if Root_Type (Bas) = Standard_String
or else
Root_Type (Bas) = Standard_Wide_String
then
Xtp := Standard_Positive;
else
Xtp := Etype (First_Index (Bas));
end if;
if Ekind (Typ) = E_String_Literal_Subtype then
Lo := String_Literal_Low_Bound (Typ);
else
Lo := Type_Low_Bound (Etype (First_Index (Typ)));
end if;
Len := String_Length (Strval (N));
if UI_From_Int (Len) > String_Type_Len (Bas) then
Apply_Compile_Time_Constraint_Error
(N, "string literal too long for}", CE_Length_Check_Failed,
Ent => Bas,
Typ => First_Subtype (Bas));
elsif Len = 0
and then not Is_Generic_Type (Xtp)
and then
Expr_Value (Lo) = Expr_Value (Type_Low_Bound (Base_Type (Xtp)))
then
Apply_Compile_Time_Constraint_Error
(N, "null string literal not allowed for}",
CE_Length_Check_Failed,
Ent => Bas,
Typ => First_Subtype (Bas));
end if;
end if;
end Eval_String_Literal;
--------------------------
-- Eval_Type_Conversion --
--------------------------
-- A type conversion is potentially static if its subtype mark is for a
-- static scalar subtype, and its operand expression is potentially static
-- (RM 4.9(10)).
procedure Eval_Type_Conversion (N : Node_Id) is
Operand : constant Node_Id := Expression (N);
Source_Type : constant Entity_Id := Etype (Operand);
Target_Type : constant Entity_Id := Etype (N);
Stat : Boolean;
Fold : Boolean;
function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean;
-- Returns true if type T is an integer type, or if it is a fixed-point
-- type to be treated as an integer (i.e. the flag Conversion_OK is set
-- on the conversion node).
function To_Be_Treated_As_Real (T : Entity_Id) return Boolean;
-- Returns true if type T is a floating-point type, or if it is a
-- fixed-point type that is not to be treated as an integer (i.e. the
-- flag Conversion_OK is not set on the conversion node).
------------------------------
-- To_Be_Treated_As_Integer --
------------------------------
function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean is
begin
return
Is_Integer_Type (T)
or else (Is_Fixed_Point_Type (T) and then Conversion_OK (N));
end To_Be_Treated_As_Integer;
---------------------------
-- To_Be_Treated_As_Real --
---------------------------
function To_Be_Treated_As_Real (T : Entity_Id) return Boolean is
begin
return
Is_Floating_Point_Type (T)
or else (Is_Fixed_Point_Type (T) and then not Conversion_OK (N));
end To_Be_Treated_As_Real;
-- Start of processing for Eval_Type_Conversion
begin
-- Cannot fold if target type is non-static or if semantic error
if not Is_Static_Subtype (Target_Type) then
Check_Non_Static_Context (Operand);
return;
elsif Error_Posted (N) then
return;
end if;
-- If not foldable we are done
Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
if not Fold then
return;
-- Don't try fold if target type has constraint error bounds
elsif not Is_OK_Static_Subtype (Target_Type) then
Set_Raises_Constraint_Error (N);
return;
end if;
-- Remaining processing depends on operand types. Note that in the
-- following type test, fixed-point counts as real unless the flag
-- Conversion_OK is set, in which case it counts as integer.
-- Fold conversion, case of string type. The result is not static
if Is_String_Type (Target_Type) then
Fold_Str (N, Strval (Get_String_Val (Operand)), Static => False);
return;
-- Fold conversion, case of integer target type
elsif To_Be_Treated_As_Integer (Target_Type) then
declare
Result : Uint;
begin
-- Integer to integer conversion
if To_Be_Treated_As_Integer (Source_Type) then
Result := Expr_Value (Operand);
-- Real to integer conversion
else
Result := UR_To_Uint (Expr_Value_R (Operand));
end if;
-- If fixed-point type (Conversion_OK must be set), then the
-- result is logically an integer, but we must replace the
-- conversion with the corresponding real literal, since the
-- type from a semantic point of view is still fixed-point.
if Is_Fixed_Point_Type (Target_Type) then
Fold_Ureal
(N, UR_From_Uint (Result) * Small_Value (Target_Type), Stat);
-- Otherwise result is integer literal
else
Fold_Uint (N, Result, Stat);
end if;
end;
-- Fold conversion, case of real target type
elsif To_Be_Treated_As_Real (Target_Type) then
declare
Result : Ureal;
begin
if To_Be_Treated_As_Real (Source_Type) then
Result := Expr_Value_R (Operand);
else
Result := UR_From_Uint (Expr_Value (Operand));
end if;
Fold_Ureal (N, Result, Stat);
end;
-- Enumeration types
else
Fold_Uint (N, Expr_Value (Operand), Stat);
end if;
if Is_Out_Of_Range (N, Etype (N), Assume_Valid => True) then
Out_Of_Range (N);
end if;
end Eval_Type_Conversion;
-------------------
-- Eval_Unary_Op --
-------------------
-- Predefined unary operators are static functions (RM 4.9(20)) and thus
-- are potentially static if the operand is potentially static (RM 4.9(7)).
procedure Eval_Unary_Op (N : Node_Id) is
Right : constant Node_Id := Right_Opnd (N);
Otype : Entity_Id := Empty;
Stat : Boolean;
Fold : Boolean;
begin
-- If not foldable we are done
Test_Expression_Is_Foldable (N, Right, Stat, Fold);
if not Fold then
return;
end if;
if Etype (Right) = Universal_Integer
or else
Etype (Right) = Universal_Real
then
Otype := Find_Universal_Operator_Type (N);
end if;
-- Fold for integer case
if Is_Integer_Type (Etype (N)) then
declare
Rint : constant Uint := Expr_Value (Right);
Result : Uint;
begin
-- In the case of modular unary plus and abs there is no need
-- to adjust the result of the operation since if the original
-- operand was in bounds the result will be in the bounds of the
-- modular type. However, in the case of modular unary minus the
-- result may go out of the bounds of the modular type and needs
-- adjustment.
if Nkind (N) = N_Op_Plus then
Result := Rint;
elsif Nkind (N) = N_Op_Minus then
if Is_Modular_Integer_Type (Etype (N)) then
Result := (-Rint) mod Modulus (Etype (N));
else
Result := (-Rint);
end if;
else
pragma Assert (Nkind (N) = N_Op_Abs);
Result := abs Rint;
end if;
Fold_Uint (N, Result, Stat);
end;
-- Fold for real case
elsif Is_Real_Type (Etype (N)) then
declare
Rreal : constant Ureal := Expr_Value_R (Right);
Result : Ureal;
begin
if Nkind (N) = N_Op_Plus then
Result := Rreal;
elsif Nkind (N) = N_Op_Minus then
Result := UR_Negate (Rreal);
else
pragma Assert (Nkind (N) = N_Op_Abs);
Result := abs Rreal;
end if;
Fold_Ureal (N, Result, Stat);
end;
end if;
-- If the operator was resolved to a specific type, make sure that type
-- is frozen even if the expression is folded into a literal (which has
-- a universal type).
if Present (Otype) then
Freeze_Before (N, Otype);
end if;
end Eval_Unary_Op;
-------------------------------
-- Eval_Unchecked_Conversion --
-------------------------------
-- Unchecked conversions can never be static, so the only required
-- processing is to check for a non-static context for the operand.
procedure Eval_Unchecked_Conversion (N : Node_Id) is
begin
Check_Non_Static_Context (Expression (N));
end Eval_Unchecked_Conversion;
--------------------
-- Expr_Rep_Value --
--------------------
function Expr_Rep_Value (N : Node_Id) return Uint is
Kind : constant Node_Kind := Nkind (N);
Ent : Entity_Id;
begin
if Is_Entity_Name (N) then
Ent := Entity (N);
-- An enumeration literal that was either in the source or created
-- as a result of static evaluation.
if Ekind (Ent) = E_Enumeration_Literal then
return Enumeration_Rep (Ent);
-- A user defined static constant
else
pragma Assert (Ekind (Ent) = E_Constant);
return Expr_Rep_Value (Constant_Value (Ent));
end if;
-- An integer literal that was either in the source or created as a
-- result of static evaluation.
elsif Kind = N_Integer_Literal then
return Intval (N);
-- A real literal for a fixed-point type. This must be the fixed-point
-- case, either the literal is of a fixed-point type, or it is a bound
-- of a fixed-point type, with type universal real. In either case we
-- obtain the desired value from Corresponding_Integer_Value.
elsif Kind = N_Real_Literal then
pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
return Corresponding_Integer_Value (N);
-- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
elsif Kind = N_Attribute_Reference
and then Attribute_Name (N) = Name_Null_Parameter
then
return Uint_0;
-- Otherwise must be character literal
else
pragma Assert (Kind = N_Character_Literal);
Ent := Entity (N);
-- Since Character literals of type Standard.Character don't have any
-- defining character literals built for them, they do not have their
-- Entity set, so just use their Char code. Otherwise for user-
-- defined character literals use their Pos value as usual which is
-- the same as the Rep value.
if No (Ent) then
return Char_Literal_Value (N);
else
return Enumeration_Rep (Ent);
end if;
end if;
end Expr_Rep_Value;
----------------
-- Expr_Value --
----------------
function Expr_Value (N : Node_Id) return Uint is
Kind : constant Node_Kind := Nkind (N);
CV_Ent : CV_Entry renames CV_Cache (Nat (N) mod CV_Cache_Size);
Ent : Entity_Id;
Val : Uint;
begin
-- If already in cache, then we know it's compile time known and we can
-- return the value that was previously stored in the cache since
-- compile time known values cannot change.
if CV_Ent.N = N then
return CV_Ent.V;
end if;
-- Otherwise proceed to test value
if Is_Entity_Name (N) then
Ent := Entity (N);
-- An enumeration literal that was either in the source or created as
-- a result of static evaluation.
if Ekind (Ent) = E_Enumeration_Literal then
Val := Enumeration_Pos (Ent);
-- A user defined static constant
else
pragma Assert (Ekind (Ent) = E_Constant);
Val := Expr_Value (Constant_Value (Ent));
end if;
-- An integer literal that was either in the source or created as a
-- result of static evaluation.
elsif Kind = N_Integer_Literal then
Val := Intval (N);
-- A real literal for a fixed-point type. This must be the fixed-point
-- case, either the literal is of a fixed-point type, or it is a bound
-- of a fixed-point type, with type universal real. In either case we
-- obtain the desired value from Corresponding_Integer_Value.
elsif Kind = N_Real_Literal then
pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
Val := Corresponding_Integer_Value (N);
-- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
elsif Kind = N_Attribute_Reference
and then Attribute_Name (N) = Name_Null_Parameter
then
Val := Uint_0;
-- Otherwise must be character literal
else
pragma Assert (Kind = N_Character_Literal);
Ent := Entity (N);
-- Since Character literals of type Standard.Character don't
-- have any defining character literals built for them, they
-- do not have their Entity set, so just use their Char
-- code. Otherwise for user-defined character literals use
-- their Pos value as usual.
if No (Ent) then
Val := Char_Literal_Value (N);
else
Val := Enumeration_Pos (Ent);
end if;
end if;
-- Come here with Val set to value to be returned, set cache
CV_Ent.N := N;
CV_Ent.V := Val;
return Val;
end Expr_Value;
------------------
-- Expr_Value_E --
------------------
function Expr_Value_E (N : Node_Id) return Entity_Id is
Ent : constant Entity_Id := Entity (N);
begin
if Ekind (Ent) = E_Enumeration_Literal then
return Ent;
else
pragma Assert (Ekind (Ent) = E_Constant);
return Expr_Value_E (Constant_Value (Ent));
end if;
end Expr_Value_E;
------------------
-- Expr_Value_R --
------------------
function Expr_Value_R (N : Node_Id) return Ureal is
Kind : constant Node_Kind := Nkind (N);
Ent : Entity_Id;
Expr : Node_Id;
begin
if Kind = N_Real_Literal then
return Realval (N);
elsif Kind = N_Identifier or else Kind = N_Expanded_Name then
Ent := Entity (N);
pragma Assert (Ekind (Ent) = E_Constant);
return Expr_Value_R (Constant_Value (Ent));
elsif Kind = N_Integer_Literal then
return UR_From_Uint (Expr_Value (N));
-- Strange case of VAX literals, which are at this stage transformed
-- into Vax_Type!x_To_y(IEEE_Literal). See Expand_N_Real_Literal in
-- Exp_Vfpt for further details.
elsif Vax_Float (Etype (N))
and then Nkind (N) = N_Unchecked_Type_Conversion
then
Expr := Expression (N);
if Nkind (Expr) = N_Function_Call
and then Present (Parameter_Associations (Expr))
then
Expr := First (Parameter_Associations (Expr));
if Nkind (Expr) = N_Real_Literal then
return Realval (Expr);
end if;
end if;
-- Peculiar VMS case, if we have xxx'Null_Parameter, return 0.0
elsif Kind = N_Attribute_Reference
and then Attribute_Name (N) = Name_Null_Parameter
then
return Ureal_0;
end if;
-- If we fall through, we have a node that cannot be interpreted as a
-- compile time constant. That is definitely an error.
raise Program_Error;
end Expr_Value_R;
------------------
-- Expr_Value_S --
------------------
function Expr_Value_S (N : Node_Id) return Node_Id is
begin
if Nkind (N) = N_String_Literal then
return N;
else
pragma Assert (Ekind (Entity (N)) = E_Constant);
return Expr_Value_S (Constant_Value (Entity (N)));
end if;
end Expr_Value_S;
----------------------------------
-- Find_Universal_Operator_Type --
----------------------------------
function Find_Universal_Operator_Type (N : Node_Id) return Entity_Id is
PN : constant Node_Id := Parent (N);
Call : constant Node_Id := Original_Node (N);
Is_Int : constant Boolean := Is_Integer_Type (Etype (N));
Is_Fix : constant Boolean :=
Nkind (N) in N_Binary_Op
and then Nkind (Right_Opnd (N)) /= Nkind (Left_Opnd (N));
-- A mixed-mode operation in this context indicates the presence of
-- fixed-point type in the designated package.
Is_Relational : constant Boolean := Etype (N) = Standard_Boolean;
-- Case where N is a relational (or membership) operator (else it is an
-- arithmetic one).
In_Membership : constant Boolean :=
Nkind (PN) in N_Membership_Test
and then
Nkind (Right_Opnd (PN)) = N_Range
and then
Is_Universal_Numeric_Type (Etype (Left_Opnd (PN)))
and then
Is_Universal_Numeric_Type
(Etype (Low_Bound (Right_Opnd (PN))))
and then
Is_Universal_Numeric_Type
(Etype (High_Bound (Right_Opnd (PN))));
-- Case where N is part of a membership test with a universal range
E : Entity_Id;
Pack : Entity_Id;
Typ1 : Entity_Id := Empty;
Priv_E : Entity_Id;
function Is_Mixed_Mode_Operand (Op : Node_Id) return Boolean;
-- Check whether one operand is a mixed-mode operation that requires the
-- presence of a fixed-point type. Given that all operands are universal
-- and have been constant-folded, retrieve the original function call.
---------------------------
-- Is_Mixed_Mode_Operand --
---------------------------
function Is_Mixed_Mode_Operand (Op : Node_Id) return Boolean is
Onod : constant Node_Id := Original_Node (Op);
begin
return Nkind (Onod) = N_Function_Call
and then Present (Next_Actual (First_Actual (Onod)))
and then Etype (First_Actual (Onod)) /=
Etype (Next_Actual (First_Actual (Onod)));
end Is_Mixed_Mode_Operand;
-- Start of processing for Find_Universal_Operator_Type
begin
if Nkind (Call) /= N_Function_Call
or else Nkind (Name (Call)) /= N_Expanded_Name
then
return Empty;
-- There are several cases where the context does not imply the type of
-- the operands:
-- - the universal expression appears in a type conversion;
-- - the expression is a relational operator applied to universal
-- operands;
-- - the expression is a membership test with a universal operand
-- and a range with universal bounds.
elsif Nkind (Parent (N)) = N_Type_Conversion
or else Is_Relational
or else In_Membership
then
Pack := Entity (Prefix (Name (Call)));
-- If the prefix is a package declared elsewhere, iterate over its
-- visible entities, otherwise iterate over all declarations in the
-- designated scope.
if Ekind (Pack) = E_Package
and then not In_Open_Scopes (Pack)
then
Priv_E := First_Private_Entity (Pack);
else
Priv_E := Empty;
end if;
Typ1 := Empty;
E := First_Entity (Pack);
while Present (E) and then E /= Priv_E loop
if Is_Numeric_Type (E)
and then Nkind (Parent (E)) /= N_Subtype_Declaration
and then Comes_From_Source (E)
and then Is_Integer_Type (E) = Is_Int
and then
(Nkind (N) in N_Unary_Op
or else Is_Relational
or else Is_Fixed_Point_Type (E) = Is_Fix)
then
if No (Typ1) then
Typ1 := E;
-- Before emitting an error, check for the presence of a
-- mixed-mode operation that specifies a fixed point type.
elsif Is_Relational
and then
(Is_Mixed_Mode_Operand (Left_Opnd (N))
or else Is_Mixed_Mode_Operand (Right_Opnd (N)))
and then Is_Fixed_Point_Type (E) /= Is_Fixed_Point_Type (Typ1)
then
if Is_Fixed_Point_Type (E) then
Typ1 := E;
end if;
else
-- More than one type of the proper class declared in P
Error_Msg_N ("ambiguous operation", N);
Error_Msg_Sloc := Sloc (Typ1);
Error_Msg_N ("\possible interpretation (inherited)#", N);
Error_Msg_Sloc := Sloc (E);
Error_Msg_N ("\possible interpretation (inherited)#", N);
return Empty;
end if;
end if;
Next_Entity (E);
end loop;
end if;
return Typ1;
end Find_Universal_Operator_Type;
--------------------------
-- Flag_Non_Static_Expr --
--------------------------
procedure Flag_Non_Static_Expr (Msg : String; Expr : Node_Id) is
begin
if Error_Posted (Expr) and then not All_Errors_Mode then
return;
else
Error_Msg_F (Msg, Expr);
Why_Not_Static (Expr);
end if;
end Flag_Non_Static_Expr;
--------------
-- Fold_Str --
--------------
procedure Fold_Str (N : Node_Id; Val : String_Id; Static : Boolean) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
begin
Rewrite (N, Make_String_Literal (Loc, Strval => Val));
-- We now have the literal with the right value, both the actual type
-- and the expected type of this literal are taken from the expression
-- that was evaluated.
Analyze (N);
Set_Is_Static_Expression (N, Static);
Set_Etype (N, Typ);
Resolve (N);
end Fold_Str;
---------------
-- Fold_Uint --
---------------
procedure Fold_Uint (N : Node_Id; Val : Uint; Static : Boolean) is
Loc : constant Source_Ptr := Sloc (N);
Typ : Entity_Id := Etype (N);
Ent : Entity_Id;
begin
-- If we are folding a named number, retain the entity in the literal,
-- for ASIS use.
if Is_Entity_Name (N)
and then Ekind (Entity (N)) = E_Named_Integer
then
Ent := Entity (N);
else
Ent := Empty;
end if;
if Is_Private_Type (Typ) then
Typ := Full_View (Typ);
end if;
-- For a result of type integer, substitute an N_Integer_Literal node
-- for the result of the compile time evaluation of the expression.
-- For ASIS use, set a link to the original named number when not in
-- a generic context.
if Is_Integer_Type (Typ) then
Rewrite (N, Make_Integer_Literal (Loc, Val));
Set_Original_Entity (N, Ent);
-- Otherwise we have an enumeration type, and we substitute either
-- an N_Identifier or N_Character_Literal to represent the enumeration
-- literal corresponding to the given value, which must always be in
-- range, because appropriate tests have already been made for this.
else pragma Assert (Is_Enumeration_Type (Typ));
Rewrite (N, Get_Enum_Lit_From_Pos (Etype (N), Val, Loc));
end if;
-- We now have the literal with the right value, both the actual type
-- and the expected type of this literal are taken from the expression
-- that was evaluated.
Analyze (N);
Set_Is_Static_Expression (N, Static);
Set_Etype (N, Typ);
Resolve (N);
end Fold_Uint;
----------------
-- Fold_Ureal --
----------------
procedure Fold_Ureal (N : Node_Id; Val : Ureal; Static : Boolean) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
Ent : Entity_Id;
begin
-- If we are folding a named number, retain the entity in the literal,
-- for ASIS use.
if Is_Entity_Name (N)
and then Ekind (Entity (N)) = E_Named_Real
then
Ent := Entity (N);
else
Ent := Empty;
end if;
Rewrite (N, Make_Real_Literal (Loc, Realval => Val));
-- Set link to original named number, for ASIS use
Set_Original_Entity (N, Ent);
-- Both the actual and expected type comes from the original expression
Analyze (N);
Set_Is_Static_Expression (N, Static);
Set_Etype (N, Typ);
Resolve (N);
end Fold_Ureal;
---------------
-- From_Bits --
---------------
function From_Bits (B : Bits; T : Entity_Id) return Uint is
V : Uint := Uint_0;
begin
for J in 0 .. B'Last loop
if B (J) then
V := V + 2 ** J;
end if;
end loop;
if Non_Binary_Modulus (T) then
V := V mod Modulus (T);
end if;
return V;
end From_Bits;
--------------------
-- Get_String_Val --
--------------------
function Get_String_Val (N : Node_Id) return Node_Id is
begin
if Nkind (N) = N_String_Literal then
return N;
elsif Nkind (N) = N_Character_Literal then
return N;
else
pragma Assert (Is_Entity_Name (N));
return Get_String_Val (Constant_Value (Entity (N)));
end if;
end Get_String_Val;
----------------
-- Initialize --
----------------
procedure Initialize is
begin
CV_Cache := (others => (Node_High_Bound, Uint_0));
end Initialize;
--------------------
-- In_Subrange_Of --
--------------------
function In_Subrange_Of
(T1 : Entity_Id;
T2 : Entity_Id;
Fixed_Int : Boolean := False) return Boolean
is
L1 : Node_Id;
H1 : Node_Id;
L2 : Node_Id;
H2 : Node_Id;
begin
if T1 = T2 or else Is_Subtype_Of (T1, T2) then
return True;
-- Never in range if both types are not scalar. Don't know if this can
-- actually happen, but just in case.
elsif not Is_Scalar_Type (T1) or else not Is_Scalar_Type (T1) then
return False;
-- If T1 has infinities but T2 doesn't have infinities, then T1 is
-- definitely not compatible with T2.
elsif Is_Floating_Point_Type (T1)
and then Has_Infinities (T1)
and then Is_Floating_Point_Type (T2)
and then not Has_Infinities (T2)
then
return False;
else
L1 := Type_Low_Bound (T1);
H1 := Type_High_Bound (T1);
L2 := Type_Low_Bound (T2);
H2 := Type_High_Bound (T2);
-- Check bounds to see if comparison possible at compile time
if Compile_Time_Compare (L1, L2, Assume_Valid => True) in Compare_GE
and then
Compile_Time_Compare (H1, H2, Assume_Valid => True) in Compare_LE
then
return True;
end if;
-- If bounds not comparable at compile time, then the bounds of T2
-- must be compile time known or we cannot answer the query.
if not Compile_Time_Known_Value (L2)
or else not Compile_Time_Known_Value (H2)
then
return False;
end if;
-- If the bounds of T1 are know at compile time then use these
-- ones, otherwise use the bounds of the base type (which are of
-- course always static).
if not Compile_Time_Known_Value (L1) then
L1 := Type_Low_Bound (Base_Type (T1));
end if;
if not Compile_Time_Known_Value (H1) then
H1 := Type_High_Bound (Base_Type (T1));
end if;
-- Fixed point types should be considered as such only if
-- flag Fixed_Int is set to False.
if Is_Floating_Point_Type (T1) or else Is_Floating_Point_Type (T2)
or else (Is_Fixed_Point_Type (T1) and then not Fixed_Int)
or else (Is_Fixed_Point_Type (T2) and then not Fixed_Int)
then
return
Expr_Value_R (L2) <= Expr_Value_R (L1)
and then
Expr_Value_R (H2) >= Expr_Value_R (H1);
else
return
Expr_Value (L2) <= Expr_Value (L1)
and then
Expr_Value (H2) >= Expr_Value (H1);
end if;
end if;
-- If any exception occurs, it means that we have some bug in the compiler
-- possibly triggered by a previous error, or by some unforeseen peculiar
-- occurrence. However, this is only an optimization attempt, so there is
-- really no point in crashing the compiler. Instead we just decide, too
-- bad, we can't figure out the answer in this case after all.
exception
when others =>
-- Debug flag K disables this behavior (useful for debugging)
if Debug_Flag_K then
raise;
else
return False;
end if;
end In_Subrange_Of;
-----------------
-- Is_In_Range --
-----------------
function Is_In_Range
(N : Node_Id;
Typ : Entity_Id;
Assume_Valid : Boolean := False;
Fixed_Int : Boolean := False;
Int_Real : Boolean := False) return Boolean
is
begin
return Test_In_Range (N, Typ, Assume_Valid, Fixed_Int, Int_Real)
= In_Range;
end Is_In_Range;
-------------------
-- Is_Null_Range --
-------------------
function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
Typ : constant Entity_Id := Etype (Lo);
begin
if not Compile_Time_Known_Value (Lo)
or else not Compile_Time_Known_Value (Hi)
then
return False;
end if;
if Is_Discrete_Type (Typ) then
return Expr_Value (Lo) > Expr_Value (Hi);
else
pragma Assert (Is_Real_Type (Typ));
return Expr_Value_R (Lo) > Expr_Value_R (Hi);
end if;
end Is_Null_Range;
-----------------------------
-- Is_OK_Static_Expression --
-----------------------------
function Is_OK_Static_Expression (N : Node_Id) return Boolean is
begin
return Is_Static_Expression (N)
and then not Raises_Constraint_Error (N);
end Is_OK_Static_Expression;
------------------------
-- Is_OK_Static_Range --
------------------------
-- A static range is a range whose bounds are static expressions, or a
-- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
-- We have already converted range attribute references, so we get the
-- "or" part of this rule without needing a special test.
function Is_OK_Static_Range (N : Node_Id) return Boolean is
begin
return Is_OK_Static_Expression (Low_Bound (N))
and then Is_OK_Static_Expression (High_Bound (N));
end Is_OK_Static_Range;
--------------------------
-- Is_OK_Static_Subtype --
--------------------------
-- Determines if Typ is a static subtype as defined in (RM 4.9(26)) where
-- neither bound raises constraint error when evaluated.
function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean is
Base_T : constant Entity_Id := Base_Type (Typ);
Anc_Subt : Entity_Id;
begin
-- First a quick check on the non static subtype flag. As described
-- in further detail in Einfo, this flag is not decisive in all cases,
-- but if it is set, then the subtype is definitely non-static.
if Is_Non_Static_Subtype (Typ) then
return False;
end if;
Anc_Subt := Ancestor_Subtype (Typ);
if Anc_Subt = Empty then
Anc_Subt := Base_T;
end if;
if Is_Generic_Type (Root_Type (Base_T))
or else Is_Generic_Actual_Type (Base_T)
then
return False;
-- String types
elsif Is_String_Type (Typ) then
return
Ekind (Typ) = E_String_Literal_Subtype
or else
(Is_OK_Static_Subtype (Component_Type (Typ))
and then Is_OK_Static_Subtype (Etype (First_Index (Typ))));
-- Scalar types
elsif Is_Scalar_Type (Typ) then
if Base_T = Typ then
return True;
else
-- Scalar_Range (Typ) might be an N_Subtype_Indication, so use
-- Get_Type_{Low,High}_Bound.
return Is_OK_Static_Subtype (Anc_Subt)
and then Is_OK_Static_Expression (Type_Low_Bound (Typ))
and then Is_OK_Static_Expression (Type_High_Bound (Typ));
end if;
-- Types other than string and scalar types are never static
else
return False;
end if;
end Is_OK_Static_Subtype;
---------------------
-- Is_Out_Of_Range --
---------------------
function Is_Out_Of_Range
(N : Node_Id;
Typ : Entity_Id;
Assume_Valid : Boolean := False;
Fixed_Int : Boolean := False;
Int_Real : Boolean := False) return Boolean
is
begin
return Test_In_Range (N, Typ, Assume_Valid, Fixed_Int, Int_Real)
= Out_Of_Range;
end Is_Out_Of_Range;
---------------------
-- Is_Static_Range --
---------------------
-- A static range is a range whose bounds are static expressions, or a
-- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
-- We have already converted range attribute references, so we get the
-- "or" part of this rule without needing a special test.
function Is_Static_Range (N : Node_Id) return Boolean is
begin
return Is_Static_Expression (Low_Bound (N))
and then Is_Static_Expression (High_Bound (N));
end Is_Static_Range;
-----------------------
-- Is_Static_Subtype --
-----------------------
-- Determines if Typ is a static subtype as defined in (RM 4.9(26))
function Is_Static_Subtype (Typ : Entity_Id) return Boolean is
Base_T : constant Entity_Id := Base_Type (Typ);
Anc_Subt : Entity_Id;
begin
-- First a quick check on the non static subtype flag. As described
-- in further detail in Einfo, this flag is not decisive in all cases,
-- but if it is set, then the subtype is definitely non-static.
if Is_Non_Static_Subtype (Typ) then
return False;
end if;
Anc_Subt := Ancestor_Subtype (Typ);
if Anc_Subt = Empty then
Anc_Subt := Base_T;
end if;
if Is_Generic_Type (Root_Type (Base_T))
or else Is_Generic_Actual_Type (Base_T)
then
return False;
-- String types
elsif Is_String_Type (Typ) then
return
Ekind (Typ) = E_String_Literal_Subtype
or else
(Is_Static_Subtype (Component_Type (Typ))
and then Is_Static_Subtype (Etype (First_Index (Typ))));
-- Scalar types
elsif Is_Scalar_Type (Typ) then
if Base_T = Typ then
return True;
else
return Is_Static_Subtype (Anc_Subt)
and then Is_Static_Expression (Type_Low_Bound (Typ))
and then Is_Static_Expression (Type_High_Bound (Typ));
end if;
-- Types other than string and scalar types are never static
else
return False;
end if;
end Is_Static_Subtype;
--------------------
-- Not_Null_Range --
--------------------
function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
Typ : constant Entity_Id := Etype (Lo);
begin
if not Compile_Time_Known_Value (Lo)
or else not Compile_Time_Known_Value (Hi)
then
return False;
end if;
if Is_Discrete_Type (Typ) then
return Expr_Value (Lo) <= Expr_Value (Hi);
else
pragma Assert (Is_Real_Type (Typ));
return Expr_Value_R (Lo) <= Expr_Value_R (Hi);
end if;
end Not_Null_Range;
-------------
-- OK_Bits --
-------------
function OK_Bits (N : Node_Id; Bits : Uint) return Boolean is
begin
-- We allow a maximum of 500,000 bits which seems a reasonable limit
if Bits < 500_000 then
return True;
else
Error_Msg_N ("static value too large, capacity exceeded", N);
return False;
end if;
end OK_Bits;
------------------
-- Out_Of_Range --
------------------
procedure Out_Of_Range (N : Node_Id) is
begin
-- If we have the static expression case, then this is an illegality
-- in Ada 95 mode, except that in an instance, we never generate an
-- error (if the error is legitimate, it was already diagnosed in the
-- template). The expression to compute the length of a packed array is
-- attached to the array type itself, and deserves a separate message.
if Is_Static_Expression (N)
and then not In_Instance
and then not In_Inlined_Body
and then Ada_Version >= Ada_95
then
if Nkind (Parent (N)) = N_Defining_Identifier
and then Is_Array_Type (Parent (N))
and then Present (Packed_Array_Type (Parent (N)))
and then Present (First_Rep_Item (Parent (N)))
then
Error_Msg_N
("length of packed array must not exceed Integer''Last",
First_Rep_Item (Parent (N)));
Rewrite (N, Make_Integer_Literal (Sloc (N), Uint_1));
else
Apply_Compile_Time_Constraint_Error
(N, "value not in range of}", CE_Range_Check_Failed);
end if;
-- Here we generate a warning for the Ada 83 case, or when we are in an
-- instance, or when we have a non-static expression case.
else
Apply_Compile_Time_Constraint_Error
(N, "value not in range of}?", CE_Range_Check_Failed);
end if;
end Out_Of_Range;
-------------------------
-- Rewrite_In_Raise_CE --
-------------------------
procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id) is
Typ : constant Entity_Id := Etype (N);
begin
-- If we want to raise CE in the condition of a N_Raise_CE node
-- we may as well get rid of the condition.
if Present (Parent (N))
and then Nkind (Parent (N)) = N_Raise_Constraint_Error
then
Set_Condition (Parent (N), Empty);
-- If the expression raising CE is a N_Raise_CE node, we can use that
-- one. We just preserve the type of the context.
elsif Nkind (Exp) = N_Raise_Constraint_Error then
Rewrite (N, Exp);
Set_Etype (N, Typ);
-- Else build an explcit N_Raise_CE
else
Rewrite (N,
Make_Raise_Constraint_Error (Sloc (Exp),
Reason => CE_Range_Check_Failed));
Set_Raises_Constraint_Error (N);
Set_Etype (N, Typ);
end if;
end Rewrite_In_Raise_CE;
---------------------
-- String_Type_Len --
---------------------
function String_Type_Len (Stype : Entity_Id) return Uint is
NT : constant Entity_Id := Etype (First_Index (Stype));
T : Entity_Id;
begin
if Is_OK_Static_Subtype (NT) then
T := NT;
else
T := Base_Type (NT);
end if;
return Expr_Value (Type_High_Bound (T)) -
Expr_Value (Type_Low_Bound (T)) + 1;
end String_Type_Len;
------------------------------------
-- Subtypes_Statically_Compatible --
------------------------------------
function Subtypes_Statically_Compatible
(T1 : Entity_Id;
T2 : Entity_Id) return Boolean
is
begin
-- Scalar types
if Is_Scalar_Type (T1) then
-- Definitely compatible if we match
if Subtypes_Statically_Match (T1, T2) then
return True;
-- If either subtype is nonstatic then they're not compatible
elsif not Is_Static_Subtype (T1)
or else not Is_Static_Subtype (T2)
then
return False;
-- If either type has constraint error bounds, then consider that
-- they match to avoid junk cascaded errors here.
elsif not Is_OK_Static_Subtype (T1)
or else not Is_OK_Static_Subtype (T2)
then
return True;
-- Base types must match, but we don't check that (should we???) but
-- we do at least check that both types are real, or both types are
-- not real.
elsif Is_Real_Type (T1) /= Is_Real_Type (T2) then
return False;
-- Here we check the bounds
else
declare
LB1 : constant Node_Id := Type_Low_Bound (T1);
HB1 : constant Node_Id := Type_High_Bound (T1);
LB2 : constant Node_Id := Type_Low_Bound (T2);
HB2 : constant Node_Id := Type_High_Bound (T2);
begin
if Is_Real_Type (T1) then
return
(Expr_Value_R (LB1) > Expr_Value_R (HB1))
or else
(Expr_Value_R (LB2) <= Expr_Value_R (LB1)
and then
Expr_Value_R (HB1) <= Expr_Value_R (HB2));
else
return
(Expr_Value (LB1) > Expr_Value (HB1))
or else
(Expr_Value (LB2) <= Expr_Value (LB1)
and then
Expr_Value (HB1) <= Expr_Value (HB2));
end if;
end;
end if;
-- Access types
elsif Is_Access_Type (T1) then
return (not Is_Constrained (T2)
or else (Subtypes_Statically_Match
(Designated_Type (T1), Designated_Type (T2))))
and then not (Can_Never_Be_Null (T2)
and then not Can_Never_Be_Null (T1));
-- All other cases
else
return (Is_Composite_Type (T1) and then not Is_Constrained (T2))
or else Subtypes_Statically_Match (T1, T2);
end if;
end Subtypes_Statically_Compatible;
-------------------------------
-- Subtypes_Statically_Match --
-------------------------------
-- Subtypes statically match if they have statically matching constraints
-- (RM 4.9.1(2)). Constraints statically match if there are none, or if
-- they are the same identical constraint, or if they are static and the
-- values match (RM 4.9.1(1)).
function Subtypes_Statically_Match (T1, T2 : Entity_Id) return Boolean is
begin
-- A type always statically matches itself
if T1 = T2 then
return True;
-- Scalar types
elsif Is_Scalar_Type (T1) then
-- Base types must be the same
if Base_Type (T1) /= Base_Type (T2) then
return False;
end if;
-- A constrained numeric subtype never matches an unconstrained
-- subtype, i.e. both types must be constrained or unconstrained.
-- To understand the requirement for this test, see RM 4.9.1(1).
-- As is made clear in RM 3.5.4(11), type Integer, for example is
-- a constrained subtype with constraint bounds matching the bounds
-- of its corresponding unconstrained base type. In this situation,
-- Integer and Integer'Base do not statically match, even though
-- they have the same bounds.
-- We only apply this test to types in Standard and types that appear
-- in user programs. That way, we do not have to be too careful about
-- setting Is_Constrained right for Itypes.
if Is_Numeric_Type (T1)
and then (Is_Constrained (T1) /= Is_Constrained (T2))
and then (Scope (T1) = Standard_Standard
or else Comes_From_Source (T1))
and then (Scope (T2) = Standard_Standard
or else Comes_From_Source (T2))
then
return False;
-- A generic scalar type does not statically match its base type
-- (AI-311). In this case we make sure that the formals, which are
-- first subtypes of their bases, are constrained.
elsif Is_Generic_Type (T1)
and then Is_Generic_Type (T2)
and then (Is_Constrained (T1) /= Is_Constrained (T2))
then
return False;
end if;
-- If there was an error in either range, then just assume the types
-- statically match to avoid further junk errors.
if No (Scalar_Range (T1)) or else No (Scalar_Range (T2))
or else Error_Posted (Scalar_Range (T1))
or else Error_Posted (Scalar_Range (T2))
then
return True;
end if;
-- Otherwise both types have bound that can be compared
declare
LB1 : constant Node_Id := Type_Low_Bound (T1);
HB1 : constant Node_Id := Type_High_Bound (T1);
LB2 : constant Node_Id := Type_Low_Bound (T2);
HB2 : constant Node_Id := Type_High_Bound (T2);
begin
-- If the bounds are the same tree node, then match
if LB1 = LB2 and then HB1 = HB2 then
return True;
-- Otherwise bounds must be static and identical value
else
if not Is_Static_Subtype (T1)
or else not Is_Static_Subtype (T2)
then
return False;
-- If either type has constraint error bounds, then say that
-- they match to avoid junk cascaded errors here.
elsif not Is_OK_Static_Subtype (T1)
or else not Is_OK_Static_Subtype (T2)
then
return True;
elsif Is_Real_Type (T1) then
return
(Expr_Value_R (LB1) = Expr_Value_R (LB2))
and then
(Expr_Value_R (HB1) = Expr_Value_R (HB2));
else
return
Expr_Value (LB1) = Expr_Value (LB2)
and then
Expr_Value (HB1) = Expr_Value (HB2);
end if;
end if;
end;
-- Type with discriminants
elsif Has_Discriminants (T1) or else Has_Discriminants (T2) then
-- Because of view exchanges in multiple instantiations, conformance
-- checking might try to match a partial view of a type with no
-- discriminants with a full view that has defaulted discriminants.
-- In such a case, use the discriminant constraint of the full view,
-- which must exist because we know that the two subtypes have the
-- same base type.
if Has_Discriminants (T1) /= Has_Discriminants (T2) then
if In_Instance then
if Is_Private_Type (T2)
and then Present (Full_View (T2))
and then Has_Discriminants (Full_View (T2))
then
return Subtypes_Statically_Match (T1, Full_View (T2));
elsif Is_Private_Type (T1)
and then Present (Full_View (T1))
and then Has_Discriminants (Full_View (T1))
then
return Subtypes_Statically_Match (Full_View (T1), T2);
else
return False;
end if;
else
return False;
end if;
end if;
declare
DL1 : constant Elist_Id := Discriminant_Constraint (T1);
DL2 : constant Elist_Id := Discriminant_Constraint (T2);
DA1 : Elmt_Id;
DA2 : Elmt_Id;
begin
if DL1 = DL2 then
return True;
elsif Is_Constrained (T1) /= Is_Constrained (T2) then
return False;
end if;
-- Now loop through the discriminant constraints
-- Note: the guard here seems necessary, since it is possible at
-- least for DL1 to be No_Elist. Not clear this is reasonable ???
if Present (DL1) and then Present (DL2) then
DA1 := First_Elmt (DL1);
DA2 := First_Elmt (DL2);
while Present (DA1) loop
declare
Expr1 : constant Node_Id := Node (DA1);
Expr2 : constant Node_Id := Node (DA2);
begin
if not Is_Static_Expression (Expr1)
or else not Is_Static_Expression (Expr2)
then
return False;
-- If either expression raised a constraint error,
-- consider the expressions as matching, since this
-- helps to prevent cascading errors.
elsif Raises_Constraint_Error (Expr1)
or else Raises_Constraint_Error (Expr2)
then
null;
elsif Expr_Value (Expr1) /= Expr_Value (Expr2) then
return False;
end if;
end;
Next_Elmt (DA1);
Next_Elmt (DA2);
end loop;
end if;
end;
return True;
-- A definite type does not match an indefinite or classwide type.
-- However, a generic type with unknown discriminants may be
-- instantiated with a type with no discriminants, and conformance
-- checking on an inherited operation may compare the actual with the
-- subtype that renames it in the instance.
elsif
Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
then
return
Is_Generic_Actual_Type (T1) or else Is_Generic_Actual_Type (T2);
-- Array type
elsif Is_Array_Type (T1) then
-- If either subtype is unconstrained then both must be, and if both
-- are unconstrained then no further checking is needed.
if not Is_Constrained (T1) or else not Is_Constrained (T2) then
return not (Is_Constrained (T1) or else Is_Constrained (T2));
end if;
-- Both subtypes are constrained, so check that the index subtypes
-- statically match.
declare
Index1 : Node_Id := First_Index (T1);
Index2 : Node_Id := First_Index (T2);
begin
while Present (Index1) loop
if not
Subtypes_Statically_Match (Etype (Index1), Etype (Index2))
then
return False;
end if;
Next_Index (Index1);
Next_Index (Index2);
end loop;
return True;
end;
elsif Is_Access_Type (T1) then
if Can_Never_Be_Null (T1) /= Can_Never_Be_Null (T2) then
return False;
elsif Ekind_In (T1, E_Access_Subprogram_Type,
E_Anonymous_Access_Subprogram_Type)
then
return
Subtype_Conformant
(Designated_Type (T1),
Designated_Type (T2));
else
return
Subtypes_Statically_Match
(Designated_Type (T1),
Designated_Type (T2))
and then Is_Access_Constant (T1) = Is_Access_Constant (T2);
end if;
-- All other types definitely match
else
return True;
end if;
end Subtypes_Statically_Match;
----------
-- Test --
----------
function Test (Cond : Boolean) return Uint is
begin
if Cond then
return Uint_1;
else
return Uint_0;
end if;
end Test;
---------------------------------
-- Test_Expression_Is_Foldable --
---------------------------------
-- One operand case
procedure Test_Expression_Is_Foldable
(N : Node_Id;
Op1 : Node_Id;
Stat : out Boolean;
Fold : out Boolean)
is
begin
Stat := False;
Fold := False;
if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
return;
end if;
-- If operand is Any_Type, just propagate to result and do not
-- try to fold, this prevents cascaded errors.
if Etype (Op1) = Any_Type then
Set_Etype (N, Any_Type);
return;
-- If operand raises constraint error, then replace node N with the
-- raise constraint error node, and we are obviously not foldable.
-- Note that this replacement inherits the Is_Static_Expression flag
-- from the operand.
elsif Raises_Constraint_Error (Op1) then
Rewrite_In_Raise_CE (N, Op1);
return;
-- If the operand is not static, then the result is not static, and
-- all we have to do is to check the operand since it is now known
-- to appear in a non-static context.
elsif not Is_Static_Expression (Op1) then
Check_Non_Static_Context (Op1);
Fold := Compile_Time_Known_Value (Op1);
return;
-- An expression of a formal modular type is not foldable because
-- the modulus is unknown.
elsif Is_Modular_Integer_Type (Etype (Op1))
and then Is_Generic_Type (Etype (Op1))
then
Check_Non_Static_Context (Op1);
return;
-- Here we have the case of an operand whose type is OK, which is
-- static, and which does not raise constraint error, we can fold.
else
Set_Is_Static_Expression (N);
Fold := True;
Stat := True;
end if;
end Test_Expression_Is_Foldable;
-- Two operand case
procedure Test_Expression_Is_Foldable
(N : Node_Id;
Op1 : Node_Id;
Op2 : Node_Id;
Stat : out Boolean;
Fold : out Boolean)
is
Rstat : constant Boolean := Is_Static_Expression (Op1)
and then Is_Static_Expression (Op2);
begin
Stat := False;
Fold := False;
if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
return;
end if;
-- If either operand is Any_Type, just propagate to result and
-- do not try to fold, this prevents cascaded errors.
if Etype (Op1) = Any_Type or else Etype (Op2) = Any_Type then
Set_Etype (N, Any_Type);
return;
-- If left operand raises constraint error, then replace node N with the
-- Raise_Constraint_Error node, and we are obviously not foldable.
-- Is_Static_Expression is set from the two operands in the normal way,
-- and we check the right operand if it is in a non-static context.
elsif Raises_Constraint_Error (Op1) then
if not Rstat then
Check_Non_Static_Context (Op2);
end if;
Rewrite_In_Raise_CE (N, Op1);
Set_Is_Static_Expression (N, Rstat);
return;
-- Similar processing for the case of the right operand. Note that we
-- don't use this routine for the short-circuit case, so we do not have
-- to worry about that special case here.
elsif Raises_Constraint_Error (Op2) then
if not Rstat then
Check_Non_Static_Context (Op1);
end if;
Rewrite_In_Raise_CE (N, Op2);
Set_Is_Static_Expression (N, Rstat);
return;
-- Exclude expressions of a generic modular type, as above
elsif Is_Modular_Integer_Type (Etype (Op1))
and then Is_Generic_Type (Etype (Op1))
then
Check_Non_Static_Context (Op1);
return;
-- If result is not static, then check non-static contexts on operands
-- since one of them may be static and the other one may not be static.
elsif not Rstat then
Check_Non_Static_Context (Op1);
Check_Non_Static_Context (Op2);
Fold := Compile_Time_Known_Value (Op1)
and then Compile_Time_Known_Value (Op2);
return;
-- Else result is static and foldable. Both operands are static, and
-- neither raises constraint error, so we can definitely fold.
else
Set_Is_Static_Expression (N);
Fold := True;
Stat := True;
return;
end if;
end Test_Expression_Is_Foldable;
-------------------
-- Test_In_Range --
-------------------
function Test_In_Range
(N : Node_Id;
Typ : Entity_Id;
Assume_Valid : Boolean;
Fixed_Int : Boolean;
Int_Real : Boolean) return Range_Membership
is
Val : Uint;
Valr : Ureal;
pragma Warnings (Off, Assume_Valid);
-- For now Assume_Valid is unreferenced since the current implementation
-- always returns Unknown if N is not a compile time known value, but we
-- keep the parameter to allow for future enhancements in which we try
-- to get the information in the variable case as well.
begin
-- Universal types have no range limits, so always in range
if Typ = Universal_Integer or else Typ = Universal_Real then
return In_Range;
-- Never known if not scalar type. Don't know if this can actually
-- happen, but our spec allows it, so we must check!
elsif not Is_Scalar_Type (Typ) then
return Unknown;
-- Never known if this is a generic type, since the bounds of generic
-- types are junk. Note that if we only checked for static expressions
-- (instead of compile time known values) below, we would not need this
-- check, because values of a generic type can never be static, but they
-- can be known at compile time.
elsif Is_Generic_Type (Typ) then
return Unknown;
-- Never known unless we have a compile time known value
elsif not Compile_Time_Known_Value (N) then
return Unknown;
-- General processing with a known compile time value
else
declare
Lo : Node_Id;
Hi : Node_Id;
LB_Known : Boolean;
HB_Known : Boolean;
begin
Lo := Type_Low_Bound (Typ);
Hi := Type_High_Bound (Typ);
LB_Known := Compile_Time_Known_Value (Lo);
HB_Known := Compile_Time_Known_Value (Hi);
-- Fixed point types should be considered as such only if flag
-- Fixed_Int is set to False.
if Is_Floating_Point_Type (Typ)
or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
or else Int_Real
then
Valr := Expr_Value_R (N);
if LB_Known and HB_Known then
if Valr >= Expr_Value_R (Lo)
and then
Valr <= Expr_Value_R (Hi)
then
return In_Range;
else
return Out_Of_Range;
end if;
elsif (LB_Known and then Valr < Expr_Value_R (Lo))
or else
(HB_Known and then Valr > Expr_Value_R (Hi))
then
return Out_Of_Range;
else
return Unknown;
end if;
else
Val := Expr_Value (N);
if LB_Known and HB_Known then
if Val >= Expr_Value (Lo)
and then
Val <= Expr_Value (Hi)
then
return In_Range;
else
return Out_Of_Range;
end if;
elsif (LB_Known and then Val < Expr_Value (Lo))
or else
(HB_Known and then Val > Expr_Value (Hi))
then
return Out_Of_Range;
else
return Unknown;
end if;
end if;
end;
end if;
end Test_In_Range;
--------------
-- To_Bits --
--------------
procedure To_Bits (U : Uint; B : out Bits) is
begin
for J in 0 .. B'Last loop
B (J) := (U / (2 ** J)) mod 2 /= 0;
end loop;
end To_Bits;
--------------------
-- Why_Not_Static --
--------------------
procedure Why_Not_Static (Expr : Node_Id) is
N : constant Node_Id := Original_Node (Expr);
Typ : Entity_Id;
E : Entity_Id;
procedure Why_Not_Static_List (L : List_Id);
-- A version that can be called on a list of expressions. Finds all
-- non-static violations in any element of the list.
-------------------------
-- Why_Not_Static_List --
-------------------------
procedure Why_Not_Static_List (L : List_Id) is
N : Node_Id;
begin
if Is_Non_Empty_List (L) then
N := First (L);
while Present (N) loop
Why_Not_Static (N);
Next (N);
end loop;
end if;
end Why_Not_Static_List;
-- Start of processing for Why_Not_Static
begin
-- If in ACATS mode (debug flag 2), then suppress all these messages,
-- this avoids massive updates to the ACATS base line.
if Debug_Flag_2 then
return;
end if;
-- Ignore call on error or empty node
if No (Expr) or else Nkind (Expr) = N_Error then
return;
end if;
-- Preprocessing for sub expressions
if Nkind (Expr) in N_Subexpr then
-- Nothing to do if expression is static
if Is_OK_Static_Expression (Expr) then
return;
end if;
-- Test for constraint error raised
if Raises_Constraint_Error (Expr) then
Error_Msg_N
("expression raises exception, cannot be static " &
"(RM 4.9(34))!", N);
return;
end if;
-- If no type, then something is pretty wrong, so ignore
Typ := Etype (Expr);
if No (Typ) then
return;
end if;
-- Type must be scalar or string type
if not Is_Scalar_Type (Typ)
and then not Is_String_Type (Typ)
then
Error_Msg_N
("static expression must have scalar or string type " &
"(RM 4.9(2))!", N);
return;
end if;
end if;
-- If we got through those checks, test particular node kind
case Nkind (N) is
when N_Expanded_Name | N_Identifier | N_Operator_Symbol =>
E := Entity (N);
if Is_Named_Number (E) then
null;
elsif Ekind (E) = E_Constant then
if not Is_Static_Expression (Constant_Value (E)) then
Error_Msg_NE
("& is not a static constant (RM 4.9(5))!", N, E);
end if;
else
Error_Msg_NE
("& is not static constant or named number " &
"(RM 4.9(5))!", N, E);
end if;
when N_Binary_Op | N_Short_Circuit | N_Membership_Test =>
if Nkind (N) in N_Op_Shift then
Error_Msg_N
("shift functions are never static (RM 4.9(6,18))!", N);
else
Why_Not_Static (Left_Opnd (N));
Why_Not_Static (Right_Opnd (N));
end if;
when N_Unary_Op =>
Why_Not_Static (Right_Opnd (N));
when N_Attribute_Reference =>
Why_Not_Static_List (Expressions (N));
E := Etype (Prefix (N));
if E = Standard_Void_Type then
return;
end if;
-- Special case non-scalar'Size since this is a common error
if Attribute_Name (N) = Name_Size then
Error_Msg_N
("size attribute is only static for static scalar type " &
"(RM 4.9(7,8))", N);
-- Flag array cases
elsif Is_Array_Type (E) then
if Attribute_Name (N) /= Name_First
and then
Attribute_Name (N) /= Name_Last
and then
Attribute_Name (N) /= Name_Length
then
Error_Msg_N
("static array attribute must be Length, First, or Last " &
"(RM 4.9(8))!", N);
-- Since we know the expression is not-static (we already
-- tested for this, must mean array is not static).
else
Error_Msg_N
("prefix is non-static array (RM 4.9(8))!", Prefix (N));
end if;
return;
-- Special case generic types, since again this is a common source
-- of confusion.
elsif Is_Generic_Actual_Type (E)
or else
Is_Generic_Type (E)
then
Error_Msg_N
("attribute of generic type is never static " &
"(RM 4.9(7,8))!", N);
elsif Is_Static_Subtype (E) then
null;
elsif Is_Scalar_Type (E) then
Error_Msg_N
("prefix type for attribute is not static scalar subtype " &
"(RM 4.9(7))!", N);
else
Error_Msg_N
("static attribute must apply to array/scalar type " &
"(RM 4.9(7,8))!", N);
end if;
when N_String_Literal =>
Error_Msg_N
("subtype of string literal is non-static (RM 4.9(4))!", N);
when N_Explicit_Dereference =>
Error_Msg_N
("explicit dereference is never static (RM 4.9)!", N);
when N_Function_Call =>
Why_Not_Static_List (Parameter_Associations (N));
Error_Msg_N ("non-static function call (RM 4.9(6,18))!", N);
when N_Parameter_Association =>
Why_Not_Static (Explicit_Actual_Parameter (N));
when N_Indexed_Component =>
Error_Msg_N
("indexed component is never static (RM 4.9)!", N);
when N_Procedure_Call_Statement =>
Error_Msg_N
("procedure call is never static (RM 4.9)!", N);
when N_Qualified_Expression =>
Why_Not_Static (Expression (N));
when N_Aggregate | N_Extension_Aggregate =>
Error_Msg_N
("an aggregate is never static (RM 4.9)!", N);
when N_Range =>
Why_Not_Static (Low_Bound (N));
Why_Not_Static (High_Bound (N));
when N_Range_Constraint =>
Why_Not_Static (Range_Expression (N));
when N_Subtype_Indication =>
Why_Not_Static (Constraint (N));
when N_Selected_Component =>
Error_Msg_N
("selected component is never static (RM 4.9)!", N);
when N_Slice =>
Error_Msg_N
("slice is never static (RM 4.9)!", N);
when N_Type_Conversion =>
Why_Not_Static (Expression (N));
if not Is_Scalar_Type (Entity (Subtype_Mark (N)))
or else not Is_Static_Subtype (Entity (Subtype_Mark (N)))
then
Error_Msg_N
("static conversion requires static scalar subtype result " &
"(RM 4.9(9))!", N);
end if;
when N_Unchecked_Type_Conversion =>
Error_Msg_N
("unchecked type conversion is never static (RM 4.9)!", N);
when others =>
null;
end case;
end Why_Not_Static;
end Sem_Eval;