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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, error types, or universal real -- types that have no usable bounds. if T = Any_Type or else not Is_Scalar_Type (T) or else T = Universal_Fixed or else T = Universal_Real 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;
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