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Diffstat (limited to 'gcc/ada/checks.adb')
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diff --git a/gcc/ada/checks.adb b/gcc/ada/checks.adb new file mode 100644 index 00000000000..b71b3ff99c1 --- /dev/null +++ b/gcc/ada/checks.adb @@ -0,0 +1,4093 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- C H E C K S -- +-- -- +-- B o d y -- +-- -- +-- $Revision: 1.205 $ +-- -- +-- Copyright (C) 1992-2001 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 2, 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 COPYING. If not, write -- +-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- +-- MA 02111-1307, USA. -- +-- -- +-- GNAT was originally developed by the GNAT team at New York University. -- +-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). -- +-- -- +------------------------------------------------------------------------------ + +with Atree; use Atree; +with Debug; use Debug; +with Einfo; use Einfo; +with Errout; use Errout; +with Exp_Ch2; use Exp_Ch2; +with Exp_Util; use Exp_Util; +with Elists; use Elists; +with Freeze; use Freeze; +with Nlists; use Nlists; +with Nmake; use Nmake; +with Opt; use Opt; +with Rtsfind; use Rtsfind; +with Sem; use Sem; +with Sem_Eval; use Sem_Eval; +with Sem_Res; use Sem_Res; +with Sem_Util; use Sem_Util; +with Sem_Warn; use Sem_Warn; +with Sinfo; use Sinfo; +with Snames; use Snames; +with Stand; use Stand; +with Tbuild; use Tbuild; +with Ttypes; use Ttypes; +with Urealp; use Urealp; +with Validsw; use Validsw; + +package body Checks is + + -- General note: many of these routines are concerned with generating + -- checking code to make sure that constraint error is raised at runtime. + -- Clearly this code is only needed if the expander is active, since + -- otherwise we will not be generating code or going into the runtime + -- execution anyway. + + -- We therefore disconnect most of these checks if the expander is + -- inactive. This has the additional benefit that we do not need to + -- worry about the tree being messed up by previous errors (since errors + -- turn off expansion anyway). + + -- There are a few exceptions to the above rule. For instance routines + -- such as Apply_Scalar_Range_Check that do not insert any code can be + -- safely called even when the Expander is inactive (but Errors_Detected + -- is 0). The benefit of executing this code when expansion is off, is + -- the ability to emit constraint error warning for static expressions + -- even when we are not generating code. + + ---------------------------- + -- Local Subprogram Specs -- + ---------------------------- + + procedure Apply_Selected_Length_Checks + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id; + Do_Static : Boolean); + -- This is the subprogram that does all the work for Apply_Length_Check + -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as + -- described for the above routines. The Do_Static flag indicates that + -- only a static check is to be done. + + procedure Apply_Selected_Range_Checks + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id; + Do_Static : Boolean); + -- This is the subprogram that does all the work for Apply_Range_Check. + -- Expr, Target_Typ and Source_Typ are as described for the above + -- routine. The Do_Static flag indicates that only a static check is + -- to be done. + + function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id; + -- If a discriminal is used in constraining a prival, Return reference + -- to the discriminal of the protected body (which renames the parameter + -- of the enclosing protected operation). This clumsy transformation is + -- needed because privals are created too late and their actual subtypes + -- are not available when analysing the bodies of the protected operations. + -- To be cleaned up??? + + function Guard_Access + (Cond : Node_Id; + Loc : Source_Ptr; + Ck_Node : Node_Id) + return Node_Id; + -- In the access type case, guard the test with a test to ensure + -- that the access value is non-null, since the checks do not + -- not apply to null access values. + + procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr); + -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the + -- Constraint_Error node. + + function Selected_Length_Checks + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id; + Warn_Node : Node_Id) + return Check_Result; + -- Like Apply_Selected_Length_Checks, except it doesn't modify + -- anything, just returns a list of nodes as described in the spec of + -- this package for the Range_Check function. + + function Selected_Range_Checks + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id; + Warn_Node : Node_Id) + return Check_Result; + -- Like Apply_Selected_Range_Checks, except it doesn't modify anything, + -- just returns a list of nodes as described in the spec of this package + -- for the Range_Check function. + + ------------------------------ + -- Access_Checks_Suppressed -- + ------------------------------ + + function Access_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Access_Checks + or else (Present (E) and then Suppress_Access_Checks (E)); + end Access_Checks_Suppressed; + + ------------------------------------- + -- Accessibility_Checks_Suppressed -- + ------------------------------------- + + function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Accessibility_Checks + or else (Present (E) and then Suppress_Accessibility_Checks (E)); + end Accessibility_Checks_Suppressed; + + ------------------------- + -- Append_Range_Checks -- + ------------------------- + + procedure Append_Range_Checks + (Checks : Check_Result; + Stmts : List_Id; + Suppress_Typ : Entity_Id; + Static_Sloc : Source_Ptr; + Flag_Node : Node_Id) + is + Internal_Flag_Node : Node_Id := Flag_Node; + Internal_Static_Sloc : Source_Ptr := Static_Sloc; + Checks_On : constant Boolean := + (not Index_Checks_Suppressed (Suppress_Typ)) + or else + (not Range_Checks_Suppressed (Suppress_Typ)); + + begin + -- For now we just return if Checks_On is false, however this should + -- be enhanced to check for an always True value in the condition + -- and to generate a compilation warning??? + + if not Checks_On then + return; + end if; + + for J in 1 .. 2 loop + exit when No (Checks (J)); + + if Nkind (Checks (J)) = N_Raise_Constraint_Error + and then Present (Condition (Checks (J))) + then + if not Has_Dynamic_Range_Check (Internal_Flag_Node) then + Append_To (Stmts, Checks (J)); + Set_Has_Dynamic_Range_Check (Internal_Flag_Node); + end if; + + else + Append_To + (Stmts, Make_Raise_Constraint_Error (Internal_Static_Sloc)); + end if; + end loop; + end Append_Range_Checks; + + ------------------------ + -- Apply_Access_Check -- + ------------------------ + + procedure Apply_Access_Check (N : Node_Id) is + P : constant Node_Id := Prefix (N); + + begin + if Inside_A_Generic then + return; + end if; + + if Is_Entity_Name (P) then + Check_Unset_Reference (P); + end if; + + if Is_Entity_Name (P) + and then Access_Checks_Suppressed (Entity (P)) + then + return; + + elsif Access_Checks_Suppressed (Etype (P)) then + return; + + else + Set_Do_Access_Check (N, True); + end if; + end Apply_Access_Check; + + ------------------------------- + -- Apply_Accessibility_Check -- + ------------------------------- + + procedure Apply_Accessibility_Check (N : Node_Id; Typ : Entity_Id) is + Loc : constant Source_Ptr := Sloc (N); + Param_Ent : constant Entity_Id := Param_Entity (N); + Param_Level : Node_Id; + Type_Level : Node_Id; + + begin + if Inside_A_Generic then + return; + + -- Only apply the run-time check if the access parameter + -- has an associated extra access level parameter and + -- when the level of the type is less deep than the level + -- of the access parameter. + + elsif Present (Param_Ent) + and then Present (Extra_Accessibility (Param_Ent)) + and then UI_Gt (Object_Access_Level (N), + Type_Access_Level (Typ)) + and then not Accessibility_Checks_Suppressed (Param_Ent) + and then not Accessibility_Checks_Suppressed (Typ) + then + Param_Level := + New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc); + + Type_Level := + Make_Integer_Literal (Loc, Type_Access_Level (Typ)); + + -- Raise Program_Error if the accessibility level of the + -- the access parameter is deeper than the level of the + -- target access type. + + Insert_Action (N, + Make_Raise_Program_Error (Loc, + Condition => + Make_Op_Gt (Loc, + Left_Opnd => Param_Level, + Right_Opnd => Type_Level))); + + Analyze_And_Resolve (N); + end if; + end Apply_Accessibility_Check; + + ------------------------------------- + -- Apply_Arithmetic_Overflow_Check -- + ------------------------------------- + + -- This routine is called only if the type is an integer type, and + -- a software arithmetic overflow check must be performed for op + -- (add, subtract, multiply). The check is performed only if + -- Software_Overflow_Checking is enabled and Do_Overflow_Check + -- is set. In this case we expand the operation into a more complex + -- sequence of tests that ensures that overflow is properly caught. + + procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is + Loc : constant Source_Ptr := Sloc (N); + Typ : constant Entity_Id := Etype (N); + Rtyp : constant Entity_Id := Root_Type (Typ); + Siz : constant Int := UI_To_Int (Esize (Rtyp)); + Dsiz : constant Int := Siz * 2; + Opnod : Node_Id; + Ctyp : Entity_Id; + Opnd : Node_Id; + Cent : RE_Id; + Lo : Uint; + Hi : Uint; + OK : Boolean; + + begin + if not Software_Overflow_Checking + or else not Do_Overflow_Check (N) + or else not Expander_Active + then + return; + end if; + + -- Nothing to do if the range of the result is known OK + + Determine_Range (N, OK, Lo, Hi); + + -- Note in the test below that we assume that if a bound of the + -- range is equal to that of the type. That's not quite accurate + -- but we do this for the following reasons: + + -- a) The way that Determine_Range works, it will typically report + -- the bounds of the value are the bounds of the type, because + -- it either can't tell anything more precise, or does not think + -- it is worth the effort to be more precise. + + -- b) It is very unusual to have a situation in which this would + -- generate an unnecessary overflow check (an example would be + -- a subtype with a range 0 .. Integer'Last - 1 to which the + -- literal value one is added. + + -- c) The alternative is a lot of special casing in this routine + -- which would partially duplicate the Determine_Range processing. + + if OK + and then Lo > Expr_Value (Type_Low_Bound (Typ)) + and then Hi < Expr_Value (Type_High_Bound (Typ)) + then + return; + end if; + + -- None of the special case optimizations worked, so there is nothing + -- for it but to generate the full general case code: + + -- x op y + + -- is expanded into + + -- Typ (Checktyp (x) op Checktyp (y)); + + -- where Typ is the type of the original expression, and Checktyp is + -- an integer type of sufficient length to hold the largest possible + -- result. + + -- In the case where check type exceeds the size of Long_Long_Integer, + -- we use a different approach, expanding to: + + -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y))) + + -- where xxx is Add, Multiply or Subtract as appropriate + + -- Find check type if one exists + + if Dsiz <= Standard_Integer_Size then + Ctyp := Standard_Integer; + + elsif Dsiz <= Standard_Long_Long_Integer_Size then + Ctyp := Standard_Long_Long_Integer; + + -- No check type exists, use runtime call + + else + if Nkind (N) = N_Op_Add then + Cent := RE_Add_With_Ovflo_Check; + + elsif Nkind (N) = N_Op_Multiply then + Cent := RE_Multiply_With_Ovflo_Check; + + else + pragma Assert (Nkind (N) = N_Op_Subtract); + Cent := RE_Subtract_With_Ovflo_Check; + end if; + + Rewrite (N, + OK_Convert_To (Typ, + Make_Function_Call (Loc, + Name => New_Reference_To (RTE (Cent), Loc), + Parameter_Associations => New_List ( + OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)), + OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N)))))); + + Analyze_And_Resolve (N, Typ); + return; + end if; + + -- If we fall through, we have the case where we do the arithmetic in + -- the next higher type and get the check by conversion. In these cases + -- Ctyp is set to the type to be used as the check type. + + Opnod := Relocate_Node (N); + + Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod)); + + Analyze (Opnd); + Set_Etype (Opnd, Ctyp); + Set_Analyzed (Opnd, True); + Set_Left_Opnd (Opnod, Opnd); + + Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod)); + + Analyze (Opnd); + Set_Etype (Opnd, Ctyp); + Set_Analyzed (Opnd, True); + Set_Right_Opnd (Opnod, Opnd); + + -- The type of the operation changes to the base type of the check + -- type, and we reset the overflow check indication, since clearly + -- no overflow is possible now that we are using a double length + -- type. We also set the Analyzed flag to avoid a recursive attempt + -- to expand the node. + + Set_Etype (Opnod, Base_Type (Ctyp)); + Set_Do_Overflow_Check (Opnod, False); + Set_Analyzed (Opnod, True); + + -- Now build the outer conversion + + Opnd := OK_Convert_To (Typ, Opnod); + + Analyze (Opnd); + Set_Etype (Opnd, Typ); + Set_Analyzed (Opnd, True); + Set_Do_Overflow_Check (Opnd, True); + + Rewrite (N, Opnd); + end Apply_Arithmetic_Overflow_Check; + + ---------------------------- + -- Apply_Array_Size_Check -- + ---------------------------- + + -- Note: Really of course this entre check should be in the backend, + -- and perhaps this is not quite the right value, but it is good + -- enough to catch the normal cases (and the relevant ACVC tests!) + + procedure Apply_Array_Size_Check (N : Node_Id; Typ : Entity_Id) is + Loc : constant Source_Ptr := Sloc (N); + Ctyp : constant Entity_Id := Component_Type (Typ); + Ent : constant Entity_Id := Defining_Identifier (N); + Decl : Node_Id; + Lo : Node_Id; + Hi : Node_Id; + Lob : Uint; + Hib : Uint; + Siz : Uint; + Xtyp : Entity_Id; + Indx : Node_Id; + Sizx : Node_Id; + Code : Node_Id; + + Static : Boolean := True; + -- Set false if any index subtye bound is non-static + + Umark : constant Uintp.Save_Mark := Uintp.Mark; + -- We can throw away all the Uint computations here, since they are + -- done only to generate boolean test results. + + Check_Siz : Uint; + -- Size to check against + + function Is_Address_Or_Import (Decl : Node_Id) return Boolean; + -- Determines if Decl is an address clause or Import/Interface pragma + -- that references the defining identifier of the current declaration. + + -------------------------- + -- Is_Address_Or_Import -- + -------------------------- + + function Is_Address_Or_Import (Decl : Node_Id) return Boolean is + begin + if Nkind (Decl) = N_At_Clause then + return Chars (Identifier (Decl)) = Chars (Ent); + + elsif Nkind (Decl) = N_Attribute_Definition_Clause then + return + Chars (Decl) = Name_Address + and then + Nkind (Name (Decl)) = N_Identifier + and then + Chars (Name (Decl)) = Chars (Ent); + + elsif Nkind (Decl) = N_Pragma then + if (Chars (Decl) = Name_Import + or else + Chars (Decl) = Name_Interface) + and then Present (Pragma_Argument_Associations (Decl)) + then + declare + F : constant Node_Id := + First (Pragma_Argument_Associations (Decl)); + + begin + return + Present (F) + and then + Present (Next (F)) + and then + Nkind (Expression (Next (F))) = N_Identifier + and then + Chars (Expression (Next (F))) = Chars (Ent); + end; + + else + return False; + end if; + + else + return False; + end if; + end Is_Address_Or_Import; + + -- Start of processing for Apply_Array_Size_Check + + begin + if not Expander_Active + or else Storage_Checks_Suppressed (Typ) + then + return; + end if; + + -- It is pointless to insert this check inside an _init_proc, because + -- that's too late, we have already built the object to be the right + -- size, and if it's too large, too bad! + + if Inside_Init_Proc then + return; + end if; + + -- Look head for pragma interface/import or address clause applying + -- to this entity. If found, we suppress the check entirely. For now + -- we only look ahead 20 declarations to stop this becoming too slow + -- Note that eventually this whole routine gets moved to gigi. + + Decl := N; + for Ctr in 1 .. 20 loop + Next (Decl); + exit when No (Decl); + + if Is_Address_Or_Import (Decl) then + return; + end if; + end loop; + + -- First step is to calculate the maximum number of elements. For this + -- calculation, we use the actual size of the subtype if it is static, + -- and if a bound of a subtype is non-static, we go to the bound of the + -- base type. + + Siz := Uint_1; + Indx := First_Index (Typ); + while Present (Indx) loop + Xtyp := Etype (Indx); + Lo := Type_Low_Bound (Xtyp); + Hi := Type_High_Bound (Xtyp); + + -- If any bound raises constraint error, we will never get this + -- far, so there is no need to generate any kind of check. + + if Raises_Constraint_Error (Lo) + or else + Raises_Constraint_Error (Hi) + then + Uintp.Release (Umark); + return; + end if; + + -- Otherwise get bounds values + + if Is_Static_Expression (Lo) then + Lob := Expr_Value (Lo); + else + Lob := Expr_Value (Type_Low_Bound (Base_Type (Xtyp))); + Static := False; + end if; + + if Is_Static_Expression (Hi) then + Hib := Expr_Value (Hi); + else + Hib := Expr_Value (Type_High_Bound (Base_Type (Xtyp))); + Static := False; + end if; + + Siz := Siz * UI_Max (Hib - Lob + 1, Uint_0); + Next_Index (Indx); + end loop; + + -- Compute the limit against which we want to check. For subprograms, + -- where the array will go on the stack, we use 8*2**24, which (in + -- bits) is the size of a 16 megabyte array. + + if Is_Subprogram (Scope (Ent)) then + Check_Siz := Uint_2 ** 27; + else + Check_Siz := Uint_2 ** 31; + end if; + + -- If we have all static bounds and Siz is too large, then we know we + -- know we have a storage error right now, so generate message + + if Static and then Siz >= Check_Siz then + Insert_Action (N, + Make_Raise_Storage_Error (Loc)); + Warn_On_Instance := True; + Error_Msg_N ("?Storage_Error will be raised at run-time", N); + Warn_On_Instance := False; + Uintp.Release (Umark); + return; + end if; + + -- Case of component size known at compile time. If the array + -- size is definitely in range, then we do not need a check. + + if Known_Esize (Ctyp) + and then Siz * Esize (Ctyp) < Check_Siz + then + Uintp.Release (Umark); + return; + end if; + + -- Here if a dynamic check is required + + -- What we do is to build an expression for the size of the array, + -- which is computed as the 'Size of the array component, times + -- the size of each dimension. + + Uintp.Release (Umark); + + Sizx := + Make_Attribute_Reference (Loc, + Prefix => New_Occurrence_Of (Ctyp, Loc), + Attribute_Name => Name_Size); + + Indx := First_Index (Typ); + + for J in 1 .. Number_Dimensions (Typ) loop + + if Sloc (Etype (Indx)) = Sloc (N) then + Ensure_Defined (Etype (Indx), N); + end if; + + Sizx := + Make_Op_Multiply (Loc, + Left_Opnd => Sizx, + Right_Opnd => + Make_Attribute_Reference (Loc, + Prefix => New_Occurrence_Of (Typ, Loc), + Attribute_Name => Name_Length, + Expressions => New_List ( + Make_Integer_Literal (Loc, J)))); + Next_Index (Indx); + end loop; + + Code := + Make_Raise_Storage_Error (Loc, + Condition => + Make_Op_Ge (Loc, + Left_Opnd => Sizx, + Right_Opnd => + Make_Integer_Literal (Loc, Check_Siz))); + + Set_Size_Check_Code (Defining_Identifier (N), Code); + Insert_Action (N, Code); + + end Apply_Array_Size_Check; + + ---------------------------- + -- Apply_Constraint_Check -- + ---------------------------- + + procedure Apply_Constraint_Check + (N : Node_Id; + Typ : Entity_Id; + No_Sliding : Boolean := False) + is + Desig_Typ : Entity_Id; + + begin + if Inside_A_Generic then + return; + + elsif Is_Scalar_Type (Typ) then + Apply_Scalar_Range_Check (N, Typ); + + elsif Is_Array_Type (Typ) then + + if Is_Constrained (Typ) then + Apply_Length_Check (N, Typ); + + if No_Sliding then + Apply_Range_Check (N, Typ); + end if; + else + Apply_Range_Check (N, Typ); + end if; + + elsif (Is_Record_Type (Typ) + or else Is_Private_Type (Typ)) + and then Has_Discriminants (Base_Type (Typ)) + and then Is_Constrained (Typ) + then + Apply_Discriminant_Check (N, Typ); + + elsif Is_Access_Type (Typ) then + + Desig_Typ := Designated_Type (Typ); + + -- No checks necessary if expression statically null + + if Nkind (N) = N_Null then + null; + + -- No sliding possible on access to arrays + + elsif Is_Array_Type (Desig_Typ) then + if Is_Constrained (Desig_Typ) then + Apply_Length_Check (N, Typ); + end if; + + Apply_Range_Check (N, Typ); + + elsif Has_Discriminants (Base_Type (Desig_Typ)) + and then Is_Constrained (Desig_Typ) + then + Apply_Discriminant_Check (N, Typ); + end if; + end if; + end Apply_Constraint_Check; + + ------------------------------ + -- Apply_Discriminant_Check -- + ------------------------------ + + procedure Apply_Discriminant_Check + (N : Node_Id; + Typ : Entity_Id; + Lhs : Node_Id := Empty) + is + Loc : constant Source_Ptr := Sloc (N); + Do_Access : constant Boolean := Is_Access_Type (Typ); + S_Typ : Entity_Id := Etype (N); + Cond : Node_Id; + T_Typ : Entity_Id; + + function Is_Aliased_Unconstrained_Component return Boolean; + -- It is possible for an aliased component to have a nominal + -- unconstrained subtype (through instantiation). If this is a + -- discriminated component assigned in the expansion of an aggregate + -- in an initialization, the check must be suppressed. This unusual + -- situation requires a predicate of its own (see 7503-008). + + ---------------------------------------- + -- Is_Aliased_Unconstrained_Component -- + ---------------------------------------- + + function Is_Aliased_Unconstrained_Component return Boolean is + Comp : Entity_Id; + Pref : Node_Id; + + begin + if Nkind (Lhs) /= N_Selected_Component then + return False; + else + Comp := Entity (Selector_Name (Lhs)); + Pref := Prefix (Lhs); + end if; + + if Ekind (Comp) /= E_Component + or else not Is_Aliased (Comp) + then + return False; + end if; + + return not Comes_From_Source (Pref) + and then In_Instance + and then not Is_Constrained (Etype (Comp)); + end Is_Aliased_Unconstrained_Component; + + -- Start of processing for Apply_Discriminant_Check + + begin + if Do_Access then + T_Typ := Designated_Type (Typ); + else + T_Typ := Typ; + end if; + + -- Nothing to do if discriminant checks are suppressed or else no code + -- is to be generated + + if not Expander_Active + or else Discriminant_Checks_Suppressed (T_Typ) + then + return; + end if; + + -- No discriminant checks necessary for access when expression + -- is statically Null. This is not only an optimization, this is + -- fundamental because otherwise discriminant checks may be generated + -- in init procs for types containing an access to a non-frozen yet + -- record, causing a deadly forward reference. + + -- Also, if the expression is of an access type whose designated + -- type is incomplete, then the access value must be null and + -- we suppress the check. + + if Nkind (N) = N_Null then + return; + + elsif Is_Access_Type (S_Typ) then + S_Typ := Designated_Type (S_Typ); + + if Ekind (S_Typ) = E_Incomplete_Type then + return; + end if; + end if; + + -- If an assignment target is present, then we need to generate + -- the actual subtype if the target is a parameter or aliased + -- object with an unconstrained nominal subtype. + + if Present (Lhs) + and then (Present (Param_Entity (Lhs)) + or else (not Is_Constrained (T_Typ) + and then Is_Aliased_View (Lhs) + and then not Is_Aliased_Unconstrained_Component)) + then + T_Typ := Get_Actual_Subtype (Lhs); + end if; + + -- Nothing to do if the type is unconstrained (this is the case + -- where the actual subtype in the RM sense of N is unconstrained + -- and no check is required). + + if not Is_Constrained (T_Typ) then + return; + end if; + + -- Suppress checks if the subtypes are the same. + -- the check must be preserved in an assignment to a formal, because + -- the constraint is given by the actual. + + if Nkind (Original_Node (N)) /= N_Allocator + and then (No (Lhs) + or else not Is_Entity_Name (Lhs) + or else (Ekind (Entity (Lhs)) /= E_In_Out_Parameter + and then Ekind (Entity (Lhs)) /= E_Out_Parameter)) + then + if (Etype (N) = Typ + or else (Do_Access and then Designated_Type (Typ) = S_Typ)) + and then not Is_Aliased_View (Lhs) + then + return; + end if; + + -- We can also eliminate checks on allocators with a subtype mark + -- that coincides with the context type. The context type may be a + -- subtype without a constraint (common case, a generic actual). + + elsif Nkind (Original_Node (N)) = N_Allocator + and then Is_Entity_Name (Expression (Original_Node (N))) + then + declare + Alloc_Typ : Entity_Id := Entity (Expression (Original_Node (N))); + + begin + if Alloc_Typ = T_Typ + or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration + and then Is_Entity_Name ( + Subtype_Indication (Parent (T_Typ))) + and then Alloc_Typ = Base_Type (T_Typ)) + + then + return; + end if; + end; + end if; + + -- See if we have a case where the types are both constrained, and + -- all the constraints are constants. In this case, we can do the + -- check successfully at compile time. + + -- we skip this check for the case where the node is a rewritten` + -- allocator, because it already carries the context subtype, and + -- extracting the discriminants from the aggregate is messy. + + if Is_Constrained (S_Typ) + and then Nkind (Original_Node (N)) /= N_Allocator + then + declare + DconT : Elmt_Id; + Discr : Entity_Id; + DconS : Elmt_Id; + ItemS : Node_Id; + ItemT : Node_Id; + + begin + -- S_Typ may not have discriminants in the case where it is a + -- private type completed by a default discriminated type. In + -- that case, we need to get the constraints from the + -- underlying_type. If the underlying type is unconstrained (i.e. + -- has no default discriminants) no check is needed. + + if Has_Discriminants (S_Typ) then + Discr := First_Discriminant (S_Typ); + DconS := First_Elmt (Discriminant_Constraint (S_Typ)); + + else + Discr := First_Discriminant (Underlying_Type (S_Typ)); + DconS := + First_Elmt + (Discriminant_Constraint (Underlying_Type (S_Typ))); + + if No (DconS) then + return; + end if; + end if; + + DconT := First_Elmt (Discriminant_Constraint (T_Typ)); + + while Present (Discr) loop + ItemS := Node (DconS); + ItemT := Node (DconT); + + exit when + not Is_OK_Static_Expression (ItemS) + or else + not Is_OK_Static_Expression (ItemT); + + if Expr_Value (ItemS) /= Expr_Value (ItemT) then + if Do_Access then -- needs run-time check. + exit; + else + Apply_Compile_Time_Constraint_Error + (N, "incorrect value for discriminant&?", Ent => Discr); + return; + end if; + end if; + + Next_Elmt (DconS); + Next_Elmt (DconT); + Next_Discriminant (Discr); + end loop; + + if No (Discr) then + return; + end if; + end; + end if; + + -- Here we need a discriminant check. First build the expression + -- for the comparisons of the discriminants: + + -- (n.disc1 /= typ.disc1) or else + -- (n.disc2 /= typ.disc2) or else + -- ... + -- (n.discn /= typ.discn) + + Cond := Build_Discriminant_Checks (N, T_Typ); + + -- If Lhs is set and is a parameter, then the condition is + -- guarded by: lhs'constrained and then (condition built above) + + if Present (Param_Entity (Lhs)) then + Cond := + Make_And_Then (Loc, + Left_Opnd => + Make_Attribute_Reference (Loc, + Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc), + Attribute_Name => Name_Constrained), + Right_Opnd => Cond); + end if; + + if Do_Access then + Cond := Guard_Access (Cond, Loc, N); + end if; + + Insert_Action (N, + Make_Raise_Constraint_Error (Loc, Condition => Cond)); + + end Apply_Discriminant_Check; + + ------------------------ + -- Apply_Divide_Check -- + ------------------------ + + procedure Apply_Divide_Check (N : Node_Id) is + Loc : constant Source_Ptr := Sloc (N); + Typ : constant Entity_Id := Etype (N); + Left : constant Node_Id := Left_Opnd (N); + Right : constant Node_Id := Right_Opnd (N); + + LLB : Uint; + Llo : Uint; + Lhi : Uint; + LOK : Boolean; + Rlo : Uint; + Rhi : Uint; + ROK : Boolean; + + begin + if Expander_Active + and then Software_Overflow_Checking + then + Determine_Range (Right, ROK, Rlo, Rhi); + + -- See if division by zero possible, and if so generate test. This + -- part of the test is not controlled by the -gnato switch. + + if Do_Division_Check (N) then + + if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then + Insert_Action (N, + Make_Raise_Constraint_Error (Loc, + Condition => + Make_Op_Eq (Loc, + Left_Opnd => Duplicate_Subexpr (Right), + Right_Opnd => Make_Integer_Literal (Loc, 0)))); + end if; + end if; + + -- Test for extremely annoying case of xxx'First divided by -1 + + if Do_Overflow_Check (N) then + + if Nkind (N) = N_Op_Divide + and then Is_Signed_Integer_Type (Typ) + then + Determine_Range (Left, LOK, Llo, Lhi); + LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ))); + + if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi)) + and then + ((not LOK) or else (Llo = LLB)) + then + Insert_Action (N, + Make_Raise_Constraint_Error (Loc, + Condition => + Make_And_Then (Loc, + + Make_Op_Eq (Loc, + Left_Opnd => Duplicate_Subexpr (Left), + Right_Opnd => Make_Integer_Literal (Loc, LLB)), + + Make_Op_Eq (Loc, + Left_Opnd => Duplicate_Subexpr (Right), + Right_Opnd => + Make_Integer_Literal (Loc, -1))))); + end if; + end if; + end if; + end if; + end Apply_Divide_Check; + + ------------------------ + -- Apply_Length_Check -- + ------------------------ + + procedure Apply_Length_Check + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id := Empty) + is + begin + Apply_Selected_Length_Checks + (Ck_Node, Target_Typ, Source_Typ, Do_Static => False); + end Apply_Length_Check; + + ----------------------- + -- Apply_Range_Check -- + ----------------------- + + procedure Apply_Range_Check + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id := Empty) + is + begin + Apply_Selected_Range_Checks + (Ck_Node, Target_Typ, Source_Typ, Do_Static => False); + end Apply_Range_Check; + + ------------------------------ + -- Apply_Scalar_Range_Check -- + ------------------------------ + + -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check + -- flag off if it is already set on. + + procedure Apply_Scalar_Range_Check + (Expr : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id := Empty; + Fixed_Int : Boolean := False) + is + Parnt : constant Node_Id := Parent (Expr); + S_Typ : Entity_Id; + Arr : Node_Id := Empty; -- initialize to prevent warning + Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning + OK : Boolean; + + Is_Subscr_Ref : Boolean; + -- Set true if Expr is a subscript + + Is_Unconstrained_Subscr_Ref : Boolean; + -- Set true if Expr is a subscript of an unconstrained array. In this + -- case we do not attempt to do an analysis of the value against the + -- range of the subscript, since we don't know the actual subtype. + + Int_Real : Boolean; + -- Set to True if Expr should be regarded as a real value + -- even though the type of Expr might be discrete. + + procedure Bad_Value; + -- Procedure called if value is determined to be out of range + + procedure Bad_Value is + begin + Apply_Compile_Time_Constraint_Error + (Expr, "value not in range of}?", + Ent => Target_Typ, + Typ => Target_Typ); + end Bad_Value; + + begin + if Inside_A_Generic then + return; + + -- Return if check obviously not needed. Note that we do not check + -- for the expander being inactive, since this routine does not + -- insert any code, but it does generate useful warnings sometimes, + -- which we would like even if we are in semantics only mode. + + elsif Target_Typ = Any_Type + or else not Is_Scalar_Type (Target_Typ) + or else Raises_Constraint_Error (Expr) + then + return; + end if; + + -- Now, see if checks are suppressed + + Is_Subscr_Ref := + Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component; + + if Is_Subscr_Ref then + Arr := Prefix (Parnt); + Arr_Typ := Get_Actual_Subtype_If_Available (Arr); + end if; + + if not Do_Range_Check (Expr) then + + -- Subscript reference. Check for Index_Checks suppressed + + if Is_Subscr_Ref then + + -- Check array type and its base type + + if Index_Checks_Suppressed (Arr_Typ) + or else Suppress_Index_Checks (Base_Type (Arr_Typ)) + then + return; + + -- Check array itself if it is an entity name + + elsif Is_Entity_Name (Arr) + and then Suppress_Index_Checks (Entity (Arr)) + then + return; + + -- Check expression itself if it is an entity name + + elsif Is_Entity_Name (Expr) + and then Suppress_Index_Checks (Entity (Expr)) + then + return; + end if; + + -- All other cases, check for Range_Checks suppressed + + else + -- Check target type and its base type + + if Range_Checks_Suppressed (Target_Typ) + or else Suppress_Range_Checks (Base_Type (Target_Typ)) + then + return; + + -- Check expression itself if it is an entity name + + elsif Is_Entity_Name (Expr) + and then Suppress_Range_Checks (Entity (Expr)) + then + return; + + -- If Expr is part of an assignment statement, then check + -- left side of assignment if it is an entity name. + + elsif Nkind (Parnt) = N_Assignment_Statement + and then Is_Entity_Name (Name (Parnt)) + and then Suppress_Range_Checks (Entity (Name (Parnt))) + then + return; + end if; + end if; + end if; + + -- Now see if we need a check + + if No (Source_Typ) then + S_Typ := Etype (Expr); + else + S_Typ := Source_Typ; + end if; + + if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then + return; + end if; + + Is_Unconstrained_Subscr_Ref := + Is_Subscr_Ref and then not Is_Constrained (Arr_Typ); + + -- Always do a range check if the source type includes infinities + -- and the target type does not include infinities. + + if Is_Floating_Point_Type (S_Typ) + and then Has_Infinities (S_Typ) + and then not Has_Infinities (Target_Typ) + then + Enable_Range_Check (Expr); + end if; + + -- Return if we know expression is definitely in the range of + -- the target type as determined by Determine_Range. Right now + -- we only do this for discrete types, and not fixed-point or + -- floating-point types. + + -- The additional less-precise tests below catch these cases. + + -- Note: skip this if we are given a source_typ, since the point + -- of supplying a Source_Typ is to stop us looking at the expression. + -- could sharpen this test to be out parameters only ??? + + if Is_Discrete_Type (Target_Typ) + and then Is_Discrete_Type (Etype (Expr)) + and then not Is_Unconstrained_Subscr_Ref + and then No (Source_Typ) + then + declare + Tlo : constant Node_Id := Type_Low_Bound (Target_Typ); + Thi : constant Node_Id := Type_High_Bound (Target_Typ); + Lo : Uint; + Hi : Uint; + + begin + if Compile_Time_Known_Value (Tlo) + and then Compile_Time_Known_Value (Thi) + then + Determine_Range (Expr, OK, Lo, Hi); + + if OK then + declare + Lov : constant Uint := Expr_Value (Tlo); + Hiv : constant Uint := Expr_Value (Thi); + + begin + if Lo >= Lov and then Hi <= Hiv then + return; + + elsif Lov > Hi or else Hiv < Lo then + Bad_Value; + return; + end if; + end; + end if; + end if; + end; + end if; + + Int_Real := + Is_Floating_Point_Type (S_Typ) + or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int); + + -- Check if we can determine at compile time whether Expr is in the + -- range of the target type. Note that if S_Typ is within the + -- bounds of Target_Typ then this must be the case. This checks is + -- only meaningful if this is not a conversion between integer and + -- real types. + + if not Is_Unconstrained_Subscr_Ref + and then + Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ) + and then + (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int) + or else + Is_In_Range (Expr, Target_Typ, Fixed_Int, Int_Real)) + then + return; + + elsif Is_Out_Of_Range (Expr, Target_Typ, Fixed_Int, Int_Real) then + Bad_Value; + return; + + -- Do not set range checks if they are killed + + elsif Nkind (Expr) = N_Unchecked_Type_Conversion + and then Kill_Range_Check (Expr) + then + return; + + -- ??? We only need a runtime check if the target type is constrained + -- (the predefined type Float is not for instance). + -- so the following should really be + -- + -- elsif Is_Constrained (Target_Typ) then + -- + -- but it isn't because certain types do not have the Is_Constrained + -- flag properly set (see 1503-003). + + else + Enable_Range_Check (Expr); + return; + end if; + + end Apply_Scalar_Range_Check; + + ---------------------------------- + -- Apply_Selected_Length_Checks -- + ---------------------------------- + + procedure Apply_Selected_Length_Checks + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id; + Do_Static : Boolean) + is + Cond : Node_Id; + R_Result : Check_Result; + R_Cno : Node_Id; + + Loc : constant Source_Ptr := Sloc (Ck_Node); + Checks_On : constant Boolean := + (not Index_Checks_Suppressed (Target_Typ)) + or else + (not Length_Checks_Suppressed (Target_Typ)); + + begin + if not Expander_Active or else not Checks_On then + return; + end if; + + R_Result := + Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty); + + for J in 1 .. 2 loop + + R_Cno := R_Result (J); + exit when No (R_Cno); + + -- A length check may mention an Itype which is attached to a + -- subsequent node. At the top level in a package this can cause + -- an order-of-elaboration problem, so we make sure that the itype + -- is referenced now. + + if Ekind (Current_Scope) = E_Package + and then Is_Compilation_Unit (Current_Scope) + then + Ensure_Defined (Target_Typ, Ck_Node); + + if Present (Source_Typ) then + Ensure_Defined (Source_Typ, Ck_Node); + + elsif Is_Itype (Etype (Ck_Node)) then + Ensure_Defined (Etype (Ck_Node), Ck_Node); + end if; + end if; + + -- If the item is a conditional raise of constraint error, + -- then have a look at what check is being performed and + -- ??? + + if Nkind (R_Cno) = N_Raise_Constraint_Error + and then Present (Condition (R_Cno)) + then + Cond := Condition (R_Cno); + + if not Has_Dynamic_Length_Check (Ck_Node) then + Insert_Action (Ck_Node, R_Cno); + + if not Do_Static then + Set_Has_Dynamic_Length_Check (Ck_Node); + end if; + + end if; + + -- Output a warning if the condition is known to be True + + if Is_Entity_Name (Cond) + and then Entity (Cond) = Standard_True + then + Apply_Compile_Time_Constraint_Error + (Ck_Node, "wrong length for array of}?", + Ent => Target_Typ, + Typ => Target_Typ); + + -- If we were only doing a static check, or if checks are not + -- on, then we want to delete the check, since it is not needed. + -- We do this by replacing the if statement by a null statement + + elsif Do_Static or else not Checks_On then + Rewrite (R_Cno, Make_Null_Statement (Loc)); + end if; + + else + Install_Static_Check (R_Cno, Loc); + end if; + + end loop; + + end Apply_Selected_Length_Checks; + + --------------------------------- + -- Apply_Selected_Range_Checks -- + --------------------------------- + + procedure Apply_Selected_Range_Checks + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id; + Do_Static : Boolean) + is + Cond : Node_Id; + R_Result : Check_Result; + R_Cno : Node_Id; + + Loc : constant Source_Ptr := Sloc (Ck_Node); + Checks_On : constant Boolean := + (not Index_Checks_Suppressed (Target_Typ)) + or else + (not Range_Checks_Suppressed (Target_Typ)); + + begin + if not Expander_Active or else not Checks_On then + return; + end if; + + R_Result := + Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty); + + for J in 1 .. 2 loop + + R_Cno := R_Result (J); + exit when No (R_Cno); + + -- If the item is a conditional raise of constraint error, + -- then have a look at what check is being performed and + -- ??? + + if Nkind (R_Cno) = N_Raise_Constraint_Error + and then Present (Condition (R_Cno)) + then + Cond := Condition (R_Cno); + + if not Has_Dynamic_Range_Check (Ck_Node) then + Insert_Action (Ck_Node, R_Cno); + + if not Do_Static then + Set_Has_Dynamic_Range_Check (Ck_Node); + end if; + end if; + + -- Output a warning if the condition is known to be True + + if Is_Entity_Name (Cond) + and then Entity (Cond) = Standard_True + then + -- Since an N_Range is technically not an expression, we + -- have to set one of the bounds to C_E and then just flag + -- the N_Range. The warning message will point to the + -- lower bound and complain about a range, which seems OK. + + if Nkind (Ck_Node) = N_Range then + Apply_Compile_Time_Constraint_Error + (Low_Bound (Ck_Node), "static range out of bounds of}?", + Ent => Target_Typ, + Typ => Target_Typ); + + Set_Raises_Constraint_Error (Ck_Node); + + else + Apply_Compile_Time_Constraint_Error + (Ck_Node, "static value out of range of}?", + Ent => Target_Typ, + Typ => Target_Typ); + end if; + + -- If we were only doing a static check, or if checks are not + -- on, then we want to delete the check, since it is not needed. + -- We do this by replacing the if statement by a null statement + + elsif Do_Static or else not Checks_On then + Rewrite (R_Cno, Make_Null_Statement (Loc)); + end if; + + else + Install_Static_Check (R_Cno, Loc); + end if; + + end loop; + + end Apply_Selected_Range_Checks; + + ------------------------------- + -- Apply_Static_Length_Check -- + ------------------------------- + + procedure Apply_Static_Length_Check + (Expr : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id := Empty) + is + begin + Apply_Selected_Length_Checks + (Expr, Target_Typ, Source_Typ, Do_Static => True); + end Apply_Static_Length_Check; + + ------------------------------------- + -- Apply_Subscript_Validity_Checks -- + ------------------------------------- + + procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is + Sub : Node_Id; + + begin + pragma Assert (Nkind (Expr) = N_Indexed_Component); + + -- Loop through subscripts + + Sub := First (Expressions (Expr)); + while Present (Sub) loop + + -- Check one subscript. Note that we do not worry about + -- enumeration type with holes, since we will convert the + -- value to a Pos value for the subscript, and that convert + -- will do the necessary validity check. + + Ensure_Valid (Sub, Holes_OK => True); + + -- Move to next subscript + + Sub := Next (Sub); + end loop; + end Apply_Subscript_Validity_Checks; + + ---------------------------------- + -- Apply_Type_Conversion_Checks -- + ---------------------------------- + + procedure Apply_Type_Conversion_Checks (N : Node_Id) is + Target_Type : constant Entity_Id := Etype (N); + Target_Base : constant Entity_Id := Base_Type (Target_Type); + + Expr : constant Node_Id := Expression (N); + Expr_Type : constant Entity_Id := Etype (Expr); + + begin + if Inside_A_Generic then + return; + + -- Skip these checks if errors detected, there are some nasty + -- situations of incomplete trees that blow things up. + + elsif Errors_Detected > 0 then + return; + + -- Scalar type conversions of the form Target_Type (Expr) require + -- two checks: + -- + -- - First there is an overflow check to insure that Expr is + -- in the base type of Target_Typ (4.6 (28)), + -- + -- - After we know Expr fits into the base type, we must perform a + -- range check to ensure that Expr meets the constraints of the + -- Target_Type. + + elsif Is_Scalar_Type (Target_Type) then + declare + Conv_OK : constant Boolean := Conversion_OK (N); + -- If the Conversion_OK flag on the type conversion is set + -- and no floating point type is involved in the type conversion + -- then fixed point values must be read as integral values. + + begin + -- Overflow check. + + if not Overflow_Checks_Suppressed (Target_Base) + and then not In_Subrange_Of (Expr_Type, Target_Base, Conv_OK) + then + Set_Do_Overflow_Check (N); + end if; + + if not Range_Checks_Suppressed (Target_Type) + and then not Range_Checks_Suppressed (Expr_Type) + then + Apply_Scalar_Range_Check + (Expr, Target_Type, Fixed_Int => Conv_OK); + end if; + end; + + elsif Comes_From_Source (N) + and then Is_Record_Type (Target_Type) + and then Is_Derived_Type (Target_Type) + and then not Is_Tagged_Type (Target_Type) + and then not Is_Constrained (Target_Type) + and then Present (Girder_Constraint (Target_Type)) + then + -- A unconstrained derived type may have inherited discriminants. + -- Build an actual discriminant constraint list using the girder + -- constraint, to verify that the expression of the parent type + -- satisfies the constraints imposed by the (unconstrained!) + -- derived type. This applies to value conversions, not to view + -- conversions of tagged types. + + declare + Loc : constant Source_Ptr := Sloc (N); + Cond : Node_Id; + Constraint : Elmt_Id; + Discr_Value : Node_Id; + Discr : Entity_Id; + New_Constraints : Elist_Id := New_Elmt_List; + Old_Constraints : Elist_Id := Discriminant_Constraint (Expr_Type); + + begin + Constraint := First_Elmt (Girder_Constraint (Target_Type)); + + while Present (Constraint) loop + Discr_Value := Node (Constraint); + + if Is_Entity_Name (Discr_Value) + and then Ekind (Entity (Discr_Value)) = E_Discriminant + then + Discr := Corresponding_Discriminant (Entity (Discr_Value)); + + if Present (Discr) + and then Scope (Discr) = Base_Type (Expr_Type) + then + -- Parent is constrained by new discriminant. Obtain + -- Value of original discriminant in expression. If + -- the new discriminant has been used to constrain more + -- than one of the girder ones, this will provide the + -- required consistency check. + + Append_Elmt ( + Make_Selected_Component (Loc, + Prefix => + Duplicate_Subexpr (Expr, Name_Req => True), + Selector_Name => + Make_Identifier (Loc, Chars (Discr))), + New_Constraints); + + else + -- Discriminant of more remote ancestor ??? + + return; + end if; + + -- Derived type definition has an explicit value for + -- this girder discriminant. + + else + Append_Elmt + (Duplicate_Subexpr (Discr_Value), New_Constraints); + end if; + + Next_Elmt (Constraint); + end loop; + + -- Use the unconstrained expression type to retrieve the + -- discriminants of the parent, and apply momentarily the + -- discriminant constraint synthesized above. + + Set_Discriminant_Constraint (Expr_Type, New_Constraints); + Cond := Build_Discriminant_Checks (Expr, Expr_Type); + Set_Discriminant_Constraint (Expr_Type, Old_Constraints); + + Insert_Action (N, + Make_Raise_Constraint_Error (Loc, Condition => Cond)); + end; + + -- should there be other checks here for array types ??? + + else + null; + end if; + + end Apply_Type_Conversion_Checks; + + ---------------------------------------------- + -- Apply_Universal_Integer_Attribute_Checks -- + ---------------------------------------------- + + procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is + Loc : constant Source_Ptr := Sloc (N); + Typ : constant Entity_Id := Etype (N); + + begin + if Inside_A_Generic then + return; + + -- Nothing to do if checks are suppressed + + elsif Range_Checks_Suppressed (Typ) + and then Overflow_Checks_Suppressed (Typ) + then + return; + + -- Nothing to do if the attribute does not come from source. The + -- internal attributes we generate of this type do not need checks, + -- and furthermore the attempt to check them causes some circular + -- elaboration orders when dealing with packed types. + + elsif not Comes_From_Source (N) then + return; + + -- Otherwise, replace the attribute node with a type conversion + -- node whose expression is the attribute, retyped to universal + -- integer, and whose subtype mark is the target type. The call + -- to analyze this conversion will set range and overflow checks + -- as required for proper detection of an out of range value. + + else + Set_Etype (N, Universal_Integer); + Set_Analyzed (N, True); + + Rewrite (N, + Make_Type_Conversion (Loc, + Subtype_Mark => New_Occurrence_Of (Typ, Loc), + Expression => Relocate_Node (N))); + + Analyze_And_Resolve (N, Typ); + return; + end if; + + end Apply_Universal_Integer_Attribute_Checks; + + ------------------------------- + -- Build_Discriminant_Checks -- + ------------------------------- + + function Build_Discriminant_Checks + (N : Node_Id; + T_Typ : Entity_Id) + return Node_Id + is + Loc : constant Source_Ptr := Sloc (N); + Cond : Node_Id; + Disc : Elmt_Id; + Disc_Ent : Entity_Id; + Dval : Node_Id; + + begin + Cond := Empty; + Disc := First_Elmt (Discriminant_Constraint (T_Typ)); + + -- For a fully private type, use the discriminants of the parent + -- type. + + if Is_Private_Type (T_Typ) + and then No (Full_View (T_Typ)) + then + Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ))); + else + Disc_Ent := First_Discriminant (T_Typ); + end if; + + while Present (Disc) loop + + Dval := Node (Disc); + + if Nkind (Dval) = N_Identifier + and then Ekind (Entity (Dval)) = E_Discriminant + then + Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc); + else + Dval := Duplicate_Subexpr (Dval); + end if; + + Evolve_Or_Else (Cond, + Make_Op_Ne (Loc, + Left_Opnd => + Make_Selected_Component (Loc, + Prefix => + Duplicate_Subexpr (N, Name_Req => True), + Selector_Name => + Make_Identifier (Loc, Chars (Disc_Ent))), + Right_Opnd => Dval)); + + Next_Elmt (Disc); + Next_Discriminant (Disc_Ent); + end loop; + + return Cond; + end Build_Discriminant_Checks; + + ----------------------------------- + -- Check_Valid_Lvalue_Subscripts -- + ----------------------------------- + + procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is + begin + -- Skip this if range checks are suppressed + + if Range_Checks_Suppressed (Etype (Expr)) then + return; + + -- Only do this check for expressions that come from source. We + -- assume that expander generated assignments explicitly include + -- any necessary checks. Note that this is not just an optimization, + -- it avoids infinite recursions! + + elsif not Comes_From_Source (Expr) then + return; + + -- For a selected component, check the prefix + + elsif Nkind (Expr) = N_Selected_Component then + Check_Valid_Lvalue_Subscripts (Prefix (Expr)); + return; + + -- Case of indexed component + + elsif Nkind (Expr) = N_Indexed_Component then + Apply_Subscript_Validity_Checks (Expr); + + -- Prefix may itself be or contain an indexed component, and + -- these subscripts need checking as well + + Check_Valid_Lvalue_Subscripts (Prefix (Expr)); + end if; + end Check_Valid_Lvalue_Subscripts; + + --------------------- + -- Determine_Range -- + --------------------- + + Cache_Size : constant := 2 ** 6; + type Cache_Index is range 0 .. Cache_Size - 1; + -- Determine size of below cache (power of 2 is more efficient!) + + Determine_Range_Cache_N : array (Cache_Index) of Node_Id; + Determine_Range_Cache_Lo : array (Cache_Index) of Uint; + Determine_Range_Cache_Hi : array (Cache_Index) of Uint; + -- The above arrays are used to implement a small direct cache + -- for Determine_Range calls. Because of the way Determine_Range + -- recursively traces subexpressions, and because overflow checking + -- calls the routine on the way up the tree, a quadratic behavior + -- can otherwise be encountered in large expressions. The cache + -- entry for node N is stored in the (N mod Cache_Size) entry, and + -- can be validated by checking the actual node value stored there. + + procedure Determine_Range + (N : Node_Id; + OK : out Boolean; + Lo : out Uint; + Hi : out Uint) + is + Typ : constant Entity_Id := Etype (N); + + Lo_Left : Uint; + Lo_Right : Uint; + Hi_Left : Uint; + Hi_Right : Uint; + Bound : Node_Id; + Hbound : Uint; + Lor : Uint; + Hir : Uint; + OK1 : Boolean; + Cindex : Cache_Index; + + function OK_Operands return Boolean; + -- Used for binary operators. Determines the ranges of the left and + -- right operands, and if they are both OK, returns True, and puts + -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left + + ----------------- + -- OK_Operands -- + ----------------- + + function OK_Operands return Boolean is + begin + Determine_Range (Left_Opnd (N), OK1, Lo_Left, Hi_Left); + + if not OK1 then + return False; + end if; + + Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right); + return OK1; + end OK_Operands; + + -- Start of processing for Determine_Range + + begin + -- Prevent junk warnings by initializing range variables + + Lo := No_Uint; + Hi := No_Uint; + Lor := No_Uint; + Hir := No_Uint; + + -- If the type is not discrete, or is undefined, then we can't + -- do anything about determining the range. + + if No (Typ) or else not Is_Discrete_Type (Typ) + or else Error_Posted (N) + then + OK := False; + return; + end if; + + -- For all other cases, we can determine the range + + OK := True; + + -- If value is compile time known, then the possible range is the + -- one value that we know this expression definitely has! + + if Compile_Time_Known_Value (N) then + Lo := Expr_Value (N); + Hi := Lo; + return; + end if; + + -- Return if already in the cache + + Cindex := Cache_Index (N mod Cache_Size); + + if Determine_Range_Cache_N (Cindex) = N then + Lo := Determine_Range_Cache_Lo (Cindex); + Hi := Determine_Range_Cache_Hi (Cindex); + return; + end if; + + -- Otherwise, start by finding the bounds of the type of the + -- expression, the value cannot be outside this range (if it + -- is, then we have an overflow situation, which is a separate + -- check, we are talking here only about the expression value). + + -- We use the actual bound unless it is dynamic, in which case + -- use the corresponding base type bound if possible. If we can't + -- get a bound then + + Bound := Type_Low_Bound (Typ); + + if Compile_Time_Known_Value (Bound) then + Lo := Expr_Value (Bound); + + elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then + Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ))); + + else + OK := False; + return; + end if; + + Bound := Type_High_Bound (Typ); + + if Compile_Time_Known_Value (Bound) then + Hi := Expr_Value (Bound); + + elsif Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then + Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ))); + Hi := Hbound; + + else + OK := False; + return; + end if; + + -- We may be able to refine this value in certain situations. If + -- refinement is possible, then Lor and Hir are set to possibly + -- tighter bounds, and OK1 is set to True. + + case Nkind (N) is + + -- For unary plus, result is limited by range of operand + + when N_Op_Plus => + Determine_Range (Right_Opnd (N), OK1, Lor, Hir); + + -- For unary minus, determine range of operand, and negate it + + when N_Op_Minus => + Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right); + + if OK1 then + Lor := -Hi_Right; + Hir := -Lo_Right; + end if; + + -- For binary addition, get range of each operand and do the + -- addition to get the result range. + + when N_Op_Add => + if OK_Operands then + Lor := Lo_Left + Lo_Right; + Hir := Hi_Left + Hi_Right; + end if; + + -- Division is tricky. The only case we consider is where the + -- right operand is a positive constant, and in this case we + -- simply divide the bounds of the left operand + + when N_Op_Divide => + if OK_Operands then + if Lo_Right = Hi_Right + and then Lo_Right > 0 + then + Lor := Lo_Left / Lo_Right; + Hir := Hi_Left / Lo_Right; + + else + OK1 := False; + end if; + end if; + + -- For binary subtraction, get range of each operand and do + -- the worst case subtraction to get the result range. + + when N_Op_Subtract => + if OK_Operands then + Lor := Lo_Left - Hi_Right; + Hir := Hi_Left - Lo_Right; + end if; + + -- For MOD, if right operand is a positive constant, then + -- result must be in the allowable range of mod results. + + when N_Op_Mod => + if OK_Operands then + if Lo_Right = Hi_Right then + if Lo_Right > 0 then + Lor := Uint_0; + Hir := Lo_Right - 1; + + elsif Lo_Right < 0 then + Lor := Lo_Right + 1; + Hir := Uint_0; + end if; + + else + OK1 := False; + end if; + end if; + + -- For REM, if right operand is a positive constant, then + -- result must be in the allowable range of mod results. + + when N_Op_Rem => + if OK_Operands then + if Lo_Right = Hi_Right then + declare + Dval : constant Uint := (abs Lo_Right) - 1; + + begin + -- The sign of the result depends on the sign of the + -- dividend (but not on the sign of the divisor, hence + -- the abs operation above). + + if Lo_Left < 0 then + Lor := -Dval; + else + Lor := Uint_0; + end if; + + if Hi_Left < 0 then + Hir := Uint_0; + else + Hir := Dval; + end if; + end; + + else + OK1 := False; + end if; + end if; + + -- Attribute reference cases + + when N_Attribute_Reference => + case Attribute_Name (N) is + + -- For Pos/Val attributes, we can refine the range using the + -- possible range of values of the attribute expression + + when Name_Pos | Name_Val => + Determine_Range (First (Expressions (N)), OK1, Lor, Hir); + + -- For Length attribute, use the bounds of the corresponding + -- index type to refine the range. + + when Name_Length => + declare + Atyp : Entity_Id := Etype (Prefix (N)); + Inum : Nat; + Indx : Node_Id; + + LL, LU : Uint; + UL, UU : Uint; + + begin + if Is_Access_Type (Atyp) then + Atyp := Designated_Type (Atyp); + end if; + + -- For string literal, we know exact value + + if Ekind (Atyp) = E_String_Literal_Subtype then + OK := True; + Lo := String_Literal_Length (Atyp); + Hi := String_Literal_Length (Atyp); + return; + end if; + + -- Otherwise check for expression given + + if No (Expressions (N)) then + Inum := 1; + else + Inum := + UI_To_Int (Expr_Value (First (Expressions (N)))); + end if; + + Indx := First_Index (Atyp); + for J in 2 .. Inum loop + Indx := Next_Index (Indx); + end loop; + + Determine_Range + (Type_Low_Bound (Etype (Indx)), OK1, LL, LU); + + if OK1 then + Determine_Range + (Type_High_Bound (Etype (Indx)), OK1, UL, UU); + + if OK1 then + + -- The maximum value for Length is the biggest + -- possible gap between the values of the bounds. + -- But of course, this value cannot be negative. + + Hir := UI_Max (Uint_0, UU - LL); + + -- For constrained arrays, the minimum value for + -- Length is taken from the actual value of the + -- bounds, since the index will be exactly of + -- this subtype. + + if Is_Constrained (Atyp) then + Lor := UI_Max (Uint_0, UL - LU); + + -- For an unconstrained array, the minimum value + -- for length is always zero. + + else + Lor := Uint_0; + end if; + end if; + end if; + end; + + -- No special handling for other attributes + -- Probably more opportunities exist here ??? + + when others => + OK1 := False; + + end case; + + -- For type conversion from one discrete type to another, we + -- can refine the range using the converted value. + + when N_Type_Conversion => + Determine_Range (Expression (N), OK1, Lor, Hir); + + -- Nothing special to do for all other expression kinds + + when others => + OK1 := False; + Lor := No_Uint; + Hir := No_Uint; + end case; + + -- At this stage, if OK1 is true, then we know that the actual + -- result of the computed expression is in the range Lor .. Hir. + -- We can use this to restrict the possible range of results. + + if OK1 then + + -- If the refined value of the low bound is greater than the + -- type high bound, then reset it to the more restrictive + -- value. However, we do NOT do this for the case of a modular + -- type where the possible upper bound on the value is above the + -- base type high bound, because that means the result could wrap. + + if Lor > Lo + and then not (Is_Modular_Integer_Type (Typ) + and then Hir > Hbound) + then + Lo := Lor; + end if; + + -- Similarly, if the refined value of the high bound is less + -- than the value so far, then reset it to the more restrictive + -- value. Again, we do not do this if the refined low bound is + -- negative for a modular type, since this would wrap. + + if Hir < Hi + and then not (Is_Modular_Integer_Type (Typ) + and then Lor < Uint_0) + then + Hi := Hir; + end if; + end if; + + -- Set cache entry for future call and we are all done + + Determine_Range_Cache_N (Cindex) := N; + Determine_Range_Cache_Lo (Cindex) := Lo; + Determine_Range_Cache_Hi (Cindex) := Hi; + return; + + -- If any exception occurs, it means that we have some bug in the compiler + -- possibly triggered by a previous error, or by some unforseen 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 a range in this case after all. + + exception + when others => + + -- Debug flag K disables this behavior (useful for debugging) + + if Debug_Flag_K then + raise; + else + OK := False; + Lo := No_Uint; + Hi := No_Uint; + return; + end if; + + end Determine_Range; + + ------------------------------------ + -- Discriminant_Checks_Suppressed -- + ------------------------------------ + + function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Discriminant_Checks + or else (Present (E) and then Suppress_Discriminant_Checks (E)); + end Discriminant_Checks_Suppressed; + + -------------------------------- + -- Division_Checks_Suppressed -- + -------------------------------- + + function Division_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Division_Checks + or else (Present (E) and then Suppress_Division_Checks (E)); + end Division_Checks_Suppressed; + + ----------------------------------- + -- Elaboration_Checks_Suppressed -- + ----------------------------------- + + function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Elaboration_Checks + or else (Present (E) and then Suppress_Elaboration_Checks (E)); + end Elaboration_Checks_Suppressed; + + ------------------------ + -- Enable_Range_Check -- + ------------------------ + + procedure Enable_Range_Check (N : Node_Id) is + begin + if Nkind (N) = N_Unchecked_Type_Conversion + and then Kill_Range_Check (N) + then + return; + else + Set_Do_Range_Check (N, True); + end if; + end Enable_Range_Check; + + ------------------ + -- Ensure_Valid -- + ------------------ + + procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is + Typ : constant Entity_Id := Etype (Expr); + + begin + -- Ignore call if we are not doing any validity checking + + if not Validity_Checks_On then + return; + + -- No check required if expression is from the expander, we assume + -- the expander will generate whatever checks are needed. Note that + -- this is not just an optimization, it avoids infinite recursions! + + -- Unchecked conversions must be checked, unless they are initialized + -- scalar values, as in a component assignment in an init_proc. + + elsif not Comes_From_Source (Expr) + and then (Nkind (Expr) /= N_Unchecked_Type_Conversion + or else Kill_Range_Check (Expr)) + then + return; + + -- No check required if expression is known to have valid value + + elsif Expr_Known_Valid (Expr) then + return; + + -- No check required if checks off + + elsif Range_Checks_Suppressed (Typ) then + return; + + -- Ignore case of enumeration with holes where the flag is set not + -- to worry about holes, since no special validity check is needed + + elsif Is_Enumeration_Type (Typ) + and then Has_Non_Standard_Rep (Typ) + and then Holes_OK + then + return; + + -- No check required on the left-hand side of an assignment. + + elsif Nkind (Parent (Expr)) = N_Assignment_Statement + and then Expr = Name (Parent (Expr)) + then + return; + + -- An annoying special case. If this is an out parameter of a scalar + -- type, then the value is not going to be accessed, therefore it is + -- inappropriate to do any validity check at the call site. + + else + -- Only need to worry about scalar types + + if Is_Scalar_Type (Typ) then + declare + P : Node_Id; + N : Node_Id; + E : Entity_Id; + F : Entity_Id; + A : Node_Id; + L : List_Id; + + begin + -- Find actual argument (which may be a parameter association) + -- and the parent of the actual argument (the call statement) + + N := Expr; + P := Parent (Expr); + + if Nkind (P) = N_Parameter_Association then + N := P; + P := Parent (N); + end if; + + -- Only need to worry if we are argument of a procedure + -- call since functions don't have out parameters. + + if Nkind (P) = N_Procedure_Call_Statement then + L := Parameter_Associations (P); + E := Entity (Name (P)); + + -- Only need to worry if there are indeed actuals, and + -- if this could be a procedure call, otherwise we cannot + -- get a match (either we are not an argument, or the + -- mode of the formal is not OUT). This test also filters + -- out the generic case. + + if Is_Non_Empty_List (L) + and then Is_Subprogram (E) + then + -- This is the loop through parameters, looking to + -- see if there is an OUT parameter for which we are + -- the argument. + + F := First_Formal (E); + A := First (L); + + while Present (F) loop + if Ekind (F) = E_Out_Parameter and then A = N then + return; + end if; + + Next_Formal (F); + Next (A); + end loop; + end if; + end if; + end; + end if; + end if; + + -- If we fall through, a validity check is required. Note that it would + -- not be good to set Do_Range_Check, even in contexts where this is + -- permissible, since this flag causes checking against the target type, + -- not the source type in contexts such as assignments + + Insert_Valid_Check (Expr); + end Ensure_Valid; + + ---------------------- + -- Expr_Known_Valid -- + ---------------------- + + function Expr_Known_Valid (Expr : Node_Id) return Boolean is + Typ : constant Entity_Id := Etype (Expr); + + begin + -- Non-scalar types are always consdered valid, since they never + -- give rise to the issues of erroneous or bounded error behavior + -- that are the concern. In formal reference manual terms the + -- notion of validity only applies to scalar types. + + if not Is_Scalar_Type (Typ) then + return True; + + -- If no validity checking, then everything is considered valid + + elsif not Validity_Checks_On then + return True; + + -- Floating-point types are considered valid unless floating-point + -- validity checks have been specifically turned on. + + elsif Is_Floating_Point_Type (Typ) + and then not Validity_Check_Floating_Point + then + return True; + + -- If the expression is the value of an object that is known to + -- be valid, then clearly the expression value itself is valid. + + elsif Is_Entity_Name (Expr) + and then Is_Known_Valid (Entity (Expr)) + then + return True; + + -- If the type is one for which all values are known valid, then + -- we are sure that the value is valid except in the slightly odd + -- case where the expression is a reference to a variable whose size + -- has been explicitly set to a value greater than the object size. + + elsif Is_Known_Valid (Typ) then + if Is_Entity_Name (Expr) + and then Ekind (Entity (Expr)) = E_Variable + and then Esize (Entity (Expr)) > Esize (Typ) + then + return False; + else + return True; + end if; + + -- Integer and character literals always have valid values, where + -- appropriate these will be range checked in any case. + + elsif Nkind (Expr) = N_Integer_Literal + or else + Nkind (Expr) = N_Character_Literal + then + return True; + + -- If we have a type conversion or a qualification of a known valid + -- value, then the result will always be valid. + + elsif Nkind (Expr) = N_Type_Conversion + or else + Nkind (Expr) = N_Qualified_Expression + then + return Expr_Known_Valid (Expression (Expr)); + + -- The result of any function call or operator is always considered + -- valid, since we assume the necessary checks are done by the call. + + elsif Nkind (Expr) in N_Binary_Op + or else + Nkind (Expr) in N_Unary_Op + or else + Nkind (Expr) = N_Function_Call + then + return True; + + -- For all other cases, we do not know the expression is valid + + else + return False; + end if; + end Expr_Known_Valid; + + --------------------- + -- Get_Discriminal -- + --------------------- + + function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is + Loc : constant Source_Ptr := Sloc (E); + D : Entity_Id; + Sc : Entity_Id; + + begin + -- The entity E is the type of a private component of the protected + -- type, or the type of a renaming of that component within a protected + -- operation of that type. + + Sc := Scope (E); + + if Ekind (Sc) /= E_Protected_Type then + Sc := Scope (Sc); + + if Ekind (Sc) /= E_Protected_Type then + return Bound; + end if; + end if; + + D := First_Discriminant (Sc); + + while Present (D) + and then Chars (D) /= Chars (Bound) + loop + Next_Discriminant (D); + end loop; + + return New_Occurrence_Of (Discriminal (D), Loc); + end Get_Discriminal; + + ------------------ + -- Guard_Access -- + ------------------ + + function Guard_Access + (Cond : Node_Id; + Loc : Source_Ptr; + Ck_Node : Node_Id) + return Node_Id + is + begin + if Nkind (Cond) = N_Or_Else then + Set_Paren_Count (Cond, 1); + end if; + + if Nkind (Ck_Node) = N_Allocator then + return Cond; + else + return + Make_And_Then (Loc, + Left_Opnd => + Make_Op_Ne (Loc, + Left_Opnd => Duplicate_Subexpr (Ck_Node), + Right_Opnd => Make_Null (Loc)), + Right_Opnd => Cond); + end if; + end Guard_Access; + + ----------------------------- + -- Index_Checks_Suppressed -- + ----------------------------- + + function Index_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Index_Checks + or else (Present (E) and then Suppress_Index_Checks (E)); + end Index_Checks_Suppressed; + + ---------------- + -- Initialize -- + ---------------- + + procedure Initialize is + begin + for J in Determine_Range_Cache_N'Range loop + Determine_Range_Cache_N (J) := Empty; + end loop; + end Initialize; + + ------------------------- + -- Insert_Range_Checks -- + ------------------------- + + procedure Insert_Range_Checks + (Checks : Check_Result; + Node : Node_Id; + Suppress_Typ : Entity_Id; + Static_Sloc : Source_Ptr := No_Location; + Flag_Node : Node_Id := Empty; + Do_Before : Boolean := False) + is + Internal_Flag_Node : Node_Id := Flag_Node; + Internal_Static_Sloc : Source_Ptr := Static_Sloc; + + Check_Node : Node_Id; + Checks_On : constant Boolean := + (not Index_Checks_Suppressed (Suppress_Typ)) + or else + (not Range_Checks_Suppressed (Suppress_Typ)); + + begin + -- For now we just return if Checks_On is false, however this should + -- be enhanced to check for an always True value in the condition + -- and to generate a compilation warning??? + + if not Expander_Active or else not Checks_On then + return; + end if; + + if Static_Sloc = No_Location then + Internal_Static_Sloc := Sloc (Node); + end if; + + if No (Flag_Node) then + Internal_Flag_Node := Node; + end if; + + for J in 1 .. 2 loop + exit when No (Checks (J)); + + if Nkind (Checks (J)) = N_Raise_Constraint_Error + and then Present (Condition (Checks (J))) + then + if not Has_Dynamic_Range_Check (Internal_Flag_Node) then + Check_Node := Checks (J); + Mark_Rewrite_Insertion (Check_Node); + + if Do_Before then + Insert_Before_And_Analyze (Node, Check_Node); + else + Insert_After_And_Analyze (Node, Check_Node); + end if; + + Set_Has_Dynamic_Range_Check (Internal_Flag_Node); + end if; + + else + Check_Node := + Make_Raise_Constraint_Error (Internal_Static_Sloc); + Mark_Rewrite_Insertion (Check_Node); + + if Do_Before then + Insert_Before_And_Analyze (Node, Check_Node); + else + Insert_After_And_Analyze (Node, Check_Node); + end if; + end if; + end loop; + end Insert_Range_Checks; + + ------------------------ + -- Insert_Valid_Check -- + ------------------------ + + procedure Insert_Valid_Check (Expr : Node_Id) is + Loc : constant Source_Ptr := Sloc (Expr); + + begin + -- Do not insert if checks off, or if not checking validity + + if Range_Checks_Suppressed (Etype (Expr)) + or else (not Validity_Checks_On) + then + null; + + -- Otherwise insert the validity check. Note that we do this with + -- validity checks turned off, to avoid recursion, we do not want + -- validity checks on the validity checking code itself! + + else + Validity_Checks_On := False; + Insert_Action + (Expr, + Make_Raise_Constraint_Error (Loc, + Condition => + Make_Op_Not (Loc, + Right_Opnd => + Make_Attribute_Reference (Loc, + Prefix => + Duplicate_Subexpr (Expr, Name_Req => True), + Attribute_Name => Name_Valid))), + Suppress => All_Checks); + Validity_Checks_On := True; + end if; + end Insert_Valid_Check; + + -------------------------- + -- Install_Static_Check -- + -------------------------- + + procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is + Stat : constant Boolean := Is_Static_Expression (R_Cno); + Typ : constant Entity_Id := Etype (R_Cno); + + begin + Rewrite (R_Cno, Make_Raise_Constraint_Error (Loc)); + Set_Analyzed (R_Cno); + Set_Etype (R_Cno, Typ); + Set_Raises_Constraint_Error (R_Cno); + Set_Is_Static_Expression (R_Cno, Stat); + end Install_Static_Check; + + ------------------------------ + -- Length_Checks_Suppressed -- + ------------------------------ + + function Length_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Length_Checks + or else (Present (E) and then Suppress_Length_Checks (E)); + end Length_Checks_Suppressed; + + -------------------------------- + -- Overflow_Checks_Suppressed -- + -------------------------------- + + function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Overflow_Checks + or else (Present (E) and then Suppress_Overflow_Checks (E)); + end Overflow_Checks_Suppressed; + + ----------------- + -- Range_Check -- + ----------------- + + function Range_Check + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id := Empty; + Warn_Node : Node_Id := Empty) + return Check_Result + is + begin + return Selected_Range_Checks + (Ck_Node, Target_Typ, Source_Typ, Warn_Node); + end Range_Check; + + ----------------------------- + -- Range_Checks_Suppressed -- + ----------------------------- + + function Range_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + -- Note: for now we always suppress range checks on Vax float types, + -- since Gigi does not know how to generate these checks. + + return Scope_Suppress.Range_Checks + or else (Present (E) and then Suppress_Range_Checks (E)) + or else Vax_Float (E); + end Range_Checks_Suppressed; + + ---------------------------- + -- Selected_Length_Checks -- + ---------------------------- + + function Selected_Length_Checks + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id; + Warn_Node : Node_Id) + return Check_Result + is + Loc : constant Source_Ptr := Sloc (Ck_Node); + S_Typ : Entity_Id; + T_Typ : Entity_Id; + Expr_Actual : Node_Id; + Exptyp : Entity_Id; + Cond : Node_Id := Empty; + Do_Access : Boolean := False; + Wnode : Node_Id := Warn_Node; + Ret_Result : Check_Result := (Empty, Empty); + Num_Checks : Natural := 0; + + procedure Add_Check (N : Node_Id); + -- Adds the action given to Ret_Result if N is non-Empty + + function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id; + function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id; + + function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean; + -- True for equal literals and for nodes that denote the same constant + -- entity, even if its value is not a static constant. This removes + -- some obviously superfluous checks. + + function Length_E_Cond + (Exptyp : Entity_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id; + -- Returns expression to compute: + -- Typ'Length /= Exptyp'Length + + function Length_N_Cond + (Expr : Node_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id; + -- Returns expression to compute: + -- Typ'Length /= Expr'Length + + --------------- + -- Add_Check -- + --------------- + + procedure Add_Check (N : Node_Id) is + begin + if Present (N) then + + -- For now, ignore attempt to place more than 2 checks ??? + + if Num_Checks = 2 then + return; + end if; + + pragma Assert (Num_Checks <= 1); + Num_Checks := Num_Checks + 1; + Ret_Result (Num_Checks) := N; + end if; + end Add_Check; + + ------------------ + -- Get_E_Length -- + ------------------ + + function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is + N : Node_Id; + E1 : Entity_Id := E; + Pt : Entity_Id := Scope (Scope (E)); + + begin + if Ekind (Scope (E)) = E_Record_Type + and then Has_Discriminants (Scope (E)) + then + N := Build_Discriminal_Subtype_Of_Component (E); + + if Present (N) then + Insert_Action (Ck_Node, N); + E1 := Defining_Identifier (N); + end if; + end if; + + if Ekind (E1) = E_String_Literal_Subtype then + return + Make_Integer_Literal (Loc, + Intval => String_Literal_Length (E1)); + + elsif Ekind (Pt) = E_Protected_Type + and then Has_Discriminants (Pt) + and then Has_Completion (Pt) + and then not Inside_Init_Proc + then + + -- If the type whose length is needed is a private component + -- constrained by a discriminant, we must expand the 'Length + -- attribute into an explicit computation, using the discriminal + -- of the current protected operation. This is because the actual + -- type of the prival is constructed after the protected opera- + -- tion has been fully expanded. + + declare + Indx_Type : Node_Id; + Lo : Node_Id; + Hi : Node_Id; + Do_Expand : Boolean := False; + + begin + Indx_Type := First_Index (E); + + for J in 1 .. Indx - 1 loop + Next_Index (Indx_Type); + end loop; + + Get_Index_Bounds (Indx_Type, Lo, Hi); + + if Nkind (Lo) = N_Identifier + and then Ekind (Entity (Lo)) = E_In_Parameter + then + Lo := Get_Discriminal (E, Lo); + Do_Expand := True; + end if; + + if Nkind (Hi) = N_Identifier + and then Ekind (Entity (Hi)) = E_In_Parameter + then + Hi := Get_Discriminal (E, Hi); + Do_Expand := True; + end if; + + if Do_Expand then + if not Is_Entity_Name (Lo) then + Lo := Duplicate_Subexpr (Lo); + end if; + + if not Is_Entity_Name (Hi) then + Lo := Duplicate_Subexpr (Hi); + end if; + + N := + Make_Op_Add (Loc, + Left_Opnd => + Make_Op_Subtract (Loc, + Left_Opnd => Hi, + Right_Opnd => Lo), + + Right_Opnd => Make_Integer_Literal (Loc, 1)); + return N; + + else + N := + Make_Attribute_Reference (Loc, + Attribute_Name => Name_Length, + Prefix => + New_Occurrence_Of (E1, Loc)); + + if Indx > 1 then + Set_Expressions (N, New_List ( + Make_Integer_Literal (Loc, Indx))); + end if; + + return N; + end if; + end; + + else + N := + Make_Attribute_Reference (Loc, + Attribute_Name => Name_Length, + Prefix => + New_Occurrence_Of (E1, Loc)); + + if Indx > 1 then + Set_Expressions (N, New_List ( + Make_Integer_Literal (Loc, Indx))); + end if; + + return N; + + end if; + end Get_E_Length; + + ------------------ + -- Get_N_Length -- + ------------------ + + function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is + begin + return + Make_Attribute_Reference (Loc, + Attribute_Name => Name_Length, + Prefix => + Duplicate_Subexpr (N, Name_Req => True), + Expressions => New_List ( + Make_Integer_Literal (Loc, Indx))); + + end Get_N_Length; + + ------------------- + -- Length_E_Cond -- + ------------------- + + function Length_E_Cond + (Exptyp : Entity_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id + is + begin + return + Make_Op_Ne (Loc, + Left_Opnd => Get_E_Length (Typ, Indx), + Right_Opnd => Get_E_Length (Exptyp, Indx)); + + end Length_E_Cond; + + ------------------- + -- Length_N_Cond -- + ------------------- + + function Length_N_Cond + (Expr : Node_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id + is + begin + return + Make_Op_Ne (Loc, + Left_Opnd => Get_E_Length (Typ, Indx), + Right_Opnd => Get_N_Length (Expr, Indx)); + + end Length_N_Cond; + + function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is + begin + return + (Nkind (L) = N_Integer_Literal + and then Nkind (R) = N_Integer_Literal + and then Intval (L) = Intval (R)) + + or else + (Is_Entity_Name (L) + and then Ekind (Entity (L)) = E_Constant + and then ((Is_Entity_Name (R) + and then Entity (L) = Entity (R)) + or else + (Nkind (R) = N_Type_Conversion + and then Is_Entity_Name (Expression (R)) + and then Entity (L) = Entity (Expression (R))))) + + or else + (Is_Entity_Name (R) + and then Ekind (Entity (R)) = E_Constant + and then Nkind (L) = N_Type_Conversion + and then Is_Entity_Name (Expression (L)) + and then Entity (R) = Entity (Expression (L))); + end Same_Bounds; + + -- Start of processing for Selected_Length_Checks + + begin + if not Expander_Active then + return Ret_Result; + end if; + + if Target_Typ = Any_Type + or else Target_Typ = Any_Composite + or else Raises_Constraint_Error (Ck_Node) + then + return Ret_Result; + end if; + + if No (Wnode) then + Wnode := Ck_Node; + end if; + + T_Typ := Target_Typ; + + if No (Source_Typ) then + S_Typ := Etype (Ck_Node); + else + S_Typ := Source_Typ; + end if; + + if S_Typ = Any_Type or else S_Typ = Any_Composite then + return Ret_Result; + end if; + + if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then + S_Typ := Designated_Type (S_Typ); + T_Typ := Designated_Type (T_Typ); + Do_Access := True; + + -- A simple optimization + + if Nkind (Ck_Node) = N_Null then + return Ret_Result; + end if; + end if; + + if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then + if Is_Constrained (T_Typ) then + + -- The checking code to be generated will freeze the + -- corresponding array type. However, we must freeze the + -- type now, so that the freeze node does not appear within + -- the generated condional expression, but ahead of it. + + Freeze_Before (Ck_Node, T_Typ); + + Expr_Actual := Get_Referenced_Object (Ck_Node); + Exptyp := Get_Actual_Subtype (Expr_Actual); + + if Is_Access_Type (Exptyp) then + Exptyp := Designated_Type (Exptyp); + end if; + + -- String_Literal case. This needs to be handled specially be- + -- cause no index types are available for string literals. The + -- condition is simply: + + -- T_Typ'Length = string-literal-length + + if Nkind (Expr_Actual) = N_String_Literal then + Cond := + Make_Op_Ne (Loc, + Left_Opnd => Get_E_Length (T_Typ, 1), + Right_Opnd => + Make_Integer_Literal (Loc, + Intval => + String_Literal_Length (Etype (Expr_Actual)))); + + -- General array case. Here we have a usable actual subtype for + -- the expression, and the condition is built from the two types + -- (Do_Length): + + -- T_Typ'Length /= Exptyp'Length or else + -- T_Typ'Length (2) /= Exptyp'Length (2) or else + -- T_Typ'Length (3) /= Exptyp'Length (3) or else + -- ... + + elsif Is_Constrained (Exptyp) then + declare + L_Index : Node_Id; + R_Index : Node_Id; + Ndims : Nat := Number_Dimensions (T_Typ); + + L_Low : Node_Id; + L_High : Node_Id; + R_Low : Node_Id; + R_High : Node_Id; + + L_Length : Uint; + R_Length : Uint; + + begin + L_Index := First_Index (T_Typ); + R_Index := First_Index (Exptyp); + + for Indx in 1 .. Ndims loop + if not (Nkind (L_Index) = N_Raise_Constraint_Error + or else Nkind (R_Index) = N_Raise_Constraint_Error) + then + Get_Index_Bounds (L_Index, L_Low, L_High); + Get_Index_Bounds (R_Index, R_Low, R_High); + + -- Deal with compile time length check. Note that we + -- skip this in the access case, because the access + -- value may be null, so we cannot know statically. + + if not Do_Access + and then Compile_Time_Known_Value (L_Low) + and then Compile_Time_Known_Value (L_High) + and then Compile_Time_Known_Value (R_Low) + and then Compile_Time_Known_Value (R_High) + then + if Expr_Value (L_High) >= Expr_Value (L_Low) then + L_Length := Expr_Value (L_High) - + Expr_Value (L_Low) + 1; + else + L_Length := UI_From_Int (0); + end if; + + if Expr_Value (R_High) >= Expr_Value (R_Low) then + R_Length := Expr_Value (R_High) - + Expr_Value (R_Low) + 1; + else + R_Length := UI_From_Int (0); + end if; + + if L_Length > R_Length then + Add_Check + (Compile_Time_Constraint_Error + (Wnode, "too few elements for}?", T_Typ)); + + elsif L_Length < R_Length then + Add_Check + (Compile_Time_Constraint_Error + (Wnode, "too many elements for}?", T_Typ)); + end if; + + -- The comparison for an individual index subtype + -- is omitted if the corresponding index subtypes + -- statically match, since the result is known to + -- be true. Note that this test is worth while even + -- though we do static evaluation, because non-static + -- subtypes can statically match. + + elsif not + Subtypes_Statically_Match + (Etype (L_Index), Etype (R_Index)) + + and then not + (Same_Bounds (L_Low, R_Low) + and then Same_Bounds (L_High, R_High)) + then + Evolve_Or_Else + (Cond, Length_E_Cond (Exptyp, T_Typ, Indx)); + end if; + + Next (L_Index); + Next (R_Index); + end if; + end loop; + end; + + -- Handle cases where we do not get a usable actual subtype that + -- is constrained. This happens for example in the function call + -- and explicit dereference cases. In these cases, we have to get + -- the length or range from the expression itself, making sure we + -- do not evaluate it more than once. + + -- Here Ck_Node is the original expression, or more properly the + -- result of applying Duplicate_Expr to the original tree, + -- forcing the result to be a name. + + else + declare + Ndims : Nat := Number_Dimensions (T_Typ); + + begin + -- Build the condition for the explicit dereference case + + for Indx in 1 .. Ndims loop + Evolve_Or_Else + (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx)); + end loop; + end; + end if; + end if; + end if; + + -- Construct the test and insert into the tree + + if Present (Cond) then + if Do_Access then + Cond := Guard_Access (Cond, Loc, Ck_Node); + end if; + + Add_Check (Make_Raise_Constraint_Error (Loc, Condition => Cond)); + end if; + + return Ret_Result; + + end Selected_Length_Checks; + + --------------------------- + -- Selected_Range_Checks -- + --------------------------- + + function Selected_Range_Checks + (Ck_Node : Node_Id; + Target_Typ : Entity_Id; + Source_Typ : Entity_Id; + Warn_Node : Node_Id) + return Check_Result + is + Loc : constant Source_Ptr := Sloc (Ck_Node); + S_Typ : Entity_Id; + T_Typ : Entity_Id; + Expr_Actual : Node_Id; + Exptyp : Entity_Id; + Cond : Node_Id := Empty; + Do_Access : Boolean := False; + Wnode : Node_Id := Warn_Node; + Ret_Result : Check_Result := (Empty, Empty); + Num_Checks : Integer := 0; + + procedure Add_Check (N : Node_Id); + -- Adds the action given to Ret_Result if N is non-Empty + + function Discrete_Range_Cond + (Expr : Node_Id; + Typ : Entity_Id) + return Node_Id; + -- Returns expression to compute: + -- Low_Bound (Expr) < Typ'First + -- or else + -- High_Bound (Expr) > Typ'Last + + function Discrete_Expr_Cond + (Expr : Node_Id; + Typ : Entity_Id) + return Node_Id; + -- Returns expression to compute: + -- Expr < Typ'First + -- or else + -- Expr > Typ'Last + + function Get_E_First_Or_Last + (E : Entity_Id; + Indx : Nat; + Nam : Name_Id) + return Node_Id; + -- Returns expression to compute: + -- E'First or E'Last + + function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id; + function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id; + -- Returns expression to compute: + -- N'First or N'Last using Duplicate_Subexpr + + function Range_E_Cond + (Exptyp : Entity_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id; + -- Returns expression to compute: + -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last + + function Range_Equal_E_Cond + (Exptyp : Entity_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id; + -- Returns expression to compute: + -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last + + function Range_N_Cond + (Expr : Node_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id; + -- Return expression to compute: + -- Expr'First < Typ'First or else Expr'Last > Typ'Last + + --------------- + -- Add_Check -- + --------------- + + procedure Add_Check (N : Node_Id) is + begin + if Present (N) then + + -- For now, ignore attempt to place more than 2 checks ??? + + if Num_Checks = 2 then + return; + end if; + + pragma Assert (Num_Checks <= 1); + Num_Checks := Num_Checks + 1; + Ret_Result (Num_Checks) := N; + end if; + end Add_Check; + + ------------------------- + -- Discrete_Expr_Cond -- + ------------------------- + + function Discrete_Expr_Cond + (Expr : Node_Id; + Typ : Entity_Id) + return Node_Id + is + begin + return + Make_Or_Else (Loc, + Left_Opnd => + Make_Op_Lt (Loc, + Left_Opnd => + Convert_To (Base_Type (Typ), Duplicate_Subexpr (Expr)), + Right_Opnd => + Convert_To (Base_Type (Typ), + Get_E_First_Or_Last (Typ, 0, Name_First))), + + Right_Opnd => + Make_Op_Gt (Loc, + Left_Opnd => + Convert_To (Base_Type (Typ), Duplicate_Subexpr (Expr)), + Right_Opnd => + Convert_To + (Base_Type (Typ), + Get_E_First_Or_Last (Typ, 0, Name_Last)))); + end Discrete_Expr_Cond; + + ------------------------- + -- Discrete_Range_Cond -- + ------------------------- + + function Discrete_Range_Cond + (Expr : Node_Id; + Typ : Entity_Id) + return Node_Id + is + LB : Node_Id := Low_Bound (Expr); + HB : Node_Id := High_Bound (Expr); + + Left_Opnd : Node_Id; + Right_Opnd : Node_Id; + + begin + if Nkind (LB) = N_Identifier + and then Ekind (Entity (LB)) = E_Discriminant then + LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc); + end if; + + if Nkind (HB) = N_Identifier + and then Ekind (Entity (HB)) = E_Discriminant then + HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc); + end if; + + Left_Opnd := + Make_Op_Lt (Loc, + Left_Opnd => + Convert_To + (Base_Type (Typ), Duplicate_Subexpr (LB)), + + Right_Opnd => + Convert_To + (Base_Type (Typ), Get_E_First_Or_Last (Typ, 0, Name_First))); + + if Base_Type (Typ) = Typ then + return Left_Opnd; + + elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ))) + and then + Compile_Time_Known_Value (High_Bound (Scalar_Range + (Base_Type (Typ)))) + then + if Is_Floating_Point_Type (Typ) then + if Expr_Value_R (High_Bound (Scalar_Range (Typ))) = + Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ)))) + then + return Left_Opnd; + end if; + + else + if Expr_Value (High_Bound (Scalar_Range (Typ))) = + Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ)))) + then + return Left_Opnd; + end if; + end if; + end if; + + Right_Opnd := + Make_Op_Gt (Loc, + Left_Opnd => + Convert_To + (Base_Type (Typ), Duplicate_Subexpr (HB)), + + Right_Opnd => + Convert_To + (Base_Type (Typ), + Get_E_First_Or_Last (Typ, 0, Name_Last))); + + return Make_Or_Else (Loc, Left_Opnd, Right_Opnd); + end Discrete_Range_Cond; + + ------------------------- + -- Get_E_First_Or_Last -- + ------------------------- + + function Get_E_First_Or_Last + (E : Entity_Id; + Indx : Nat; + Nam : Name_Id) + return Node_Id + is + N : Node_Id; + LB : Node_Id; + HB : Node_Id; + Bound : Node_Id; + + begin + if Is_Array_Type (E) then + N := First_Index (E); + + for J in 2 .. Indx loop + Next_Index (N); + end loop; + + else + N := Scalar_Range (E); + end if; + + if Nkind (N) = N_Subtype_Indication then + LB := Low_Bound (Range_Expression (Constraint (N))); + HB := High_Bound (Range_Expression (Constraint (N))); + + elsif Is_Entity_Name (N) then + LB := Type_Low_Bound (Etype (N)); + HB := Type_High_Bound (Etype (N)); + + else + LB := Low_Bound (N); + HB := High_Bound (N); + end if; + + if Nam = Name_First then + Bound := LB; + else + Bound := HB; + end if; + + if Nkind (Bound) = N_Identifier + and then Ekind (Entity (Bound)) = E_Discriminant + then + return New_Occurrence_Of (Discriminal (Entity (Bound)), Loc); + + elsif Nkind (Bound) = N_Identifier + and then Ekind (Entity (Bound)) = E_In_Parameter + and then not Inside_Init_Proc + then + return Get_Discriminal (E, Bound); + + elsif Nkind (Bound) = N_Integer_Literal then + return Make_Integer_Literal (Loc, Intval (Bound)); + + else + return Duplicate_Subexpr (Bound); + end if; + end Get_E_First_Or_Last; + + ----------------- + -- Get_N_First -- + ----------------- + + function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is + begin + return + Make_Attribute_Reference (Loc, + Attribute_Name => Name_First, + Prefix => + Duplicate_Subexpr (N, Name_Req => True), + Expressions => New_List ( + Make_Integer_Literal (Loc, Indx))); + + end Get_N_First; + + ---------------- + -- Get_N_Last -- + ---------------- + + function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is + begin + return + Make_Attribute_Reference (Loc, + Attribute_Name => Name_Last, + Prefix => + Duplicate_Subexpr (N, Name_Req => True), + Expressions => New_List ( + Make_Integer_Literal (Loc, Indx))); + + end Get_N_Last; + + ------------------ + -- Range_E_Cond -- + ------------------ + + function Range_E_Cond + (Exptyp : Entity_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id + is + begin + return + Make_Or_Else (Loc, + Left_Opnd => + Make_Op_Lt (Loc, + Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First), + Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)), + + Right_Opnd => + Make_Op_Gt (Loc, + Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last), + Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last))); + + end Range_E_Cond; + + ------------------------ + -- Range_Equal_E_Cond -- + ------------------------ + + function Range_Equal_E_Cond + (Exptyp : Entity_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id + is + begin + return + Make_Or_Else (Loc, + Left_Opnd => + Make_Op_Ne (Loc, + Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First), + Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)), + Right_Opnd => + Make_Op_Ne (Loc, + Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last), + Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last))); + end Range_Equal_E_Cond; + + ------------------ + -- Range_N_Cond -- + ------------------ + + function Range_N_Cond + (Expr : Node_Id; + Typ : Entity_Id; + Indx : Nat) + return Node_Id + is + begin + return + Make_Or_Else (Loc, + Left_Opnd => + Make_Op_Lt (Loc, + Left_Opnd => Get_N_First (Expr, Indx), + Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)), + + Right_Opnd => + Make_Op_Gt (Loc, + Left_Opnd => Get_N_Last (Expr, Indx), + Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last))); + end Range_N_Cond; + + -- Start of processing for Selected_Range_Checks + + begin + if not Expander_Active then + return Ret_Result; + end if; + + if Target_Typ = Any_Type + or else Target_Typ = Any_Composite + or else Raises_Constraint_Error (Ck_Node) + then + return Ret_Result; + end if; + + if No (Wnode) then + Wnode := Ck_Node; + end if; + + T_Typ := Target_Typ; + + if No (Source_Typ) then + S_Typ := Etype (Ck_Node); + else + S_Typ := Source_Typ; + end if; + + if S_Typ = Any_Type or else S_Typ = Any_Composite then + return Ret_Result; + end if; + + -- The order of evaluating T_Typ before S_Typ seems to be critical + -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed + -- in, and since Node can be an N_Range node, it might be invalid. + -- Should there be an assert check somewhere for taking the Etype of + -- an N_Range node ??? + + if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then + S_Typ := Designated_Type (S_Typ); + T_Typ := Designated_Type (T_Typ); + Do_Access := True; + + -- A simple optimization + + if Nkind (Ck_Node) = N_Null then + return Ret_Result; + end if; + end if; + + -- For an N_Range Node, check for a null range and then if not + -- null generate a range check action. + + if Nkind (Ck_Node) = N_Range then + + -- There's no point in checking a range against itself + + if Ck_Node = Scalar_Range (T_Typ) then + return Ret_Result; + end if; + + declare + T_LB : constant Node_Id := Type_Low_Bound (T_Typ); + T_HB : constant Node_Id := Type_High_Bound (T_Typ); + LB : constant Node_Id := Low_Bound (Ck_Node); + HB : constant Node_Id := High_Bound (Ck_Node); + Null_Range : Boolean; + + Out_Of_Range_L : Boolean; + Out_Of_Range_H : Boolean; + + begin + -- Check for case where everything is static and we can + -- do the check at compile time. This is skipped if we + -- have an access type, since the access value may be null. + + -- ??? This code can be improved since you only need to know + -- that the two respective bounds (LB & T_LB or HB & T_HB) + -- are known at compile time to emit pertinent messages. + + if Compile_Time_Known_Value (LB) + and then Compile_Time_Known_Value (HB) + and then Compile_Time_Known_Value (T_LB) + and then Compile_Time_Known_Value (T_HB) + and then not Do_Access + then + -- Floating-point case + + if Is_Floating_Point_Type (S_Typ) then + Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB); + Out_Of_Range_L := + (Expr_Value_R (LB) < Expr_Value_R (T_LB)) + or else + (Expr_Value_R (LB) > Expr_Value_R (T_HB)); + + Out_Of_Range_H := + (Expr_Value_R (HB) > Expr_Value_R (T_HB)) + or else + (Expr_Value_R (HB) < Expr_Value_R (T_LB)); + + -- Fixed or discrete type case + + else + Null_Range := Expr_Value (HB) < Expr_Value (LB); + Out_Of_Range_L := + (Expr_Value (LB) < Expr_Value (T_LB)) + or else + (Expr_Value (LB) > Expr_Value (T_HB)); + + Out_Of_Range_H := + (Expr_Value (HB) > Expr_Value (T_HB)) + or else + (Expr_Value (HB) < Expr_Value (T_LB)); + end if; + + if not Null_Range then + if Out_Of_Range_L then + if No (Warn_Node) then + Add_Check + (Compile_Time_Constraint_Error + (Low_Bound (Ck_Node), + "static value out of range of}?", T_Typ)); + + else + Add_Check + (Compile_Time_Constraint_Error + (Wnode, + "static range out of bounds of}?", T_Typ)); + end if; + end if; + + if Out_Of_Range_H then + if No (Warn_Node) then + Add_Check + (Compile_Time_Constraint_Error + (High_Bound (Ck_Node), + "static value out of range of}?", T_Typ)); + + else + Add_Check + (Compile_Time_Constraint_Error + (Wnode, + "static range out of bounds of}?", T_Typ)); + end if; + end if; + + end if; + + else + declare + LB : Node_Id := Low_Bound (Ck_Node); + HB : Node_Id := High_Bound (Ck_Node); + + begin + + -- If either bound is a discriminant and we are within + -- the record declaration, it is a use of the discriminant + -- in a constraint of a component, and nothing can be + -- checked here. The check will be emitted within the + -- init_proc. Before then, the discriminal has no real + -- meaning. + + if Nkind (LB) = N_Identifier + and then Ekind (Entity (LB)) = E_Discriminant + then + if Current_Scope = Scope (Entity (LB)) then + return Ret_Result; + else + LB := + New_Occurrence_Of (Discriminal (Entity (LB)), Loc); + end if; + end if; + + if Nkind (HB) = N_Identifier + and then Ekind (Entity (HB)) = E_Discriminant + then + if Current_Scope = Scope (Entity (HB)) then + return Ret_Result; + else + HB := + New_Occurrence_Of (Discriminal (Entity (HB)), Loc); + end if; + end if; + + Cond := Discrete_Range_Cond (Ck_Node, T_Typ); + Set_Paren_Count (Cond, 1); + + Cond := + Make_And_Then (Loc, + Left_Opnd => + Make_Op_Ge (Loc, + Left_Opnd => Duplicate_Subexpr (HB), + Right_Opnd => Duplicate_Subexpr (LB)), + Right_Opnd => Cond); + end; + + end if; + end; + + elsif Is_Scalar_Type (S_Typ) then + + -- This somewhat duplicates what Apply_Scalar_Range_Check does, + -- except the above simply sets a flag in the node and lets + -- gigi generate the check base on the Etype of the expression. + -- Sometimes, however we want to do a dynamic check against an + -- arbitrary target type, so we do that here. + + if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then + Cond := Discrete_Expr_Cond (Ck_Node, T_Typ); + + -- For literals, we can tell if the constraint error will be + -- raised at compile time, so we never need a dynamic check, but + -- if the exception will be raised, then post the usual warning, + -- and replace the literal with a raise constraint error + -- expression. As usual, skip this for access types + + elsif Compile_Time_Known_Value (Ck_Node) + and then not Do_Access + then + declare + LB : constant Node_Id := Type_Low_Bound (T_Typ); + UB : constant Node_Id := Type_High_Bound (T_Typ); + + Out_Of_Range : Boolean; + Static_Bounds : constant Boolean := + Compile_Time_Known_Value (LB) + and Compile_Time_Known_Value (UB); + + begin + -- Following range tests should use Sem_Eval routine ??? + + if Static_Bounds then + if Is_Floating_Point_Type (S_Typ) then + Out_Of_Range := + (Expr_Value_R (Ck_Node) < Expr_Value_R (LB)) + or else + (Expr_Value_R (Ck_Node) > Expr_Value_R (UB)); + + else -- fixed or discrete type + Out_Of_Range := + Expr_Value (Ck_Node) < Expr_Value (LB) + or else + Expr_Value (Ck_Node) > Expr_Value (UB); + end if; + + -- Bounds of the type are static and the literal is + -- out of range so make a warning message. + + if Out_Of_Range then + if No (Warn_Node) then + Add_Check + (Compile_Time_Constraint_Error + (Ck_Node, + "static value out of range of}?", T_Typ)); + + else + Add_Check + (Compile_Time_Constraint_Error + (Wnode, + "static value out of range of}?", T_Typ)); + end if; + end if; + + else + Cond := Discrete_Expr_Cond (Ck_Node, T_Typ); + end if; + end; + + -- Here for the case of a non-static expression, we need a runtime + -- check unless the source type range is guaranteed to be in the + -- range of the target type. + + else + if not In_Subrange_Of (S_Typ, T_Typ) then + Cond := Discrete_Expr_Cond (Ck_Node, T_Typ); + end if; + end if; + end if; + + if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then + if Is_Constrained (T_Typ) then + + Expr_Actual := Get_Referenced_Object (Ck_Node); + Exptyp := Get_Actual_Subtype (Expr_Actual); + + if Is_Access_Type (Exptyp) then + Exptyp := Designated_Type (Exptyp); + end if; + + -- String_Literal case. This needs to be handled specially be- + -- cause no index types are available for string literals. The + -- condition is simply: + + -- T_Typ'Length = string-literal-length + + if Nkind (Expr_Actual) = N_String_Literal then + null; + + -- General array case. Here we have a usable actual subtype for + -- the expression, and the condition is built from the two types + + -- T_Typ'First < Exptyp'First or else + -- T_Typ'Last > Exptyp'Last or else + -- T_Typ'First(1) < Exptyp'First(1) or else + -- T_Typ'Last(1) > Exptyp'Last(1) or else + -- ... + + elsif Is_Constrained (Exptyp) then + declare + L_Index : Node_Id; + R_Index : Node_Id; + Ndims : Nat := Number_Dimensions (T_Typ); + + L_Low : Node_Id; + L_High : Node_Id; + R_Low : Node_Id; + R_High : Node_Id; + + begin + L_Index := First_Index (T_Typ); + R_Index := First_Index (Exptyp); + + for Indx in 1 .. Ndims loop + if not (Nkind (L_Index) = N_Raise_Constraint_Error + or else Nkind (R_Index) = N_Raise_Constraint_Error) + then + Get_Index_Bounds (L_Index, L_Low, L_High); + Get_Index_Bounds (R_Index, R_Low, R_High); + + -- Deal with compile time length check. Note that we + -- skip this in the access case, because the access + -- value may be null, so we cannot know statically. + + if not + Subtypes_Statically_Match + (Etype (L_Index), Etype (R_Index)) + then + -- If the target type is constrained then we + -- have to check for exact equality of bounds + -- (required for qualified expressions). + + if Is_Constrained (T_Typ) then + Evolve_Or_Else + (Cond, + Range_Equal_E_Cond (Exptyp, T_Typ, Indx)); + + else + Evolve_Or_Else + (Cond, Range_E_Cond (Exptyp, T_Typ, Indx)); + end if; + end if; + + Next (L_Index); + Next (R_Index); + + end if; + end loop; + end; + + -- Handle cases where we do not get a usable actual subtype that + -- is constrained. This happens for example in the function call + -- and explicit dereference cases. In these cases, we have to get + -- the length or range from the expression itself, making sure we + -- do not evaluate it more than once. + + -- Here Ck_Node is the original expression, or more properly the + -- result of applying Duplicate_Expr to the original tree, + -- forcing the result to be a name. + + else + declare + Ndims : Nat := Number_Dimensions (T_Typ); + + begin + -- Build the condition for the explicit dereference case + + for Indx in 1 .. Ndims loop + Evolve_Or_Else + (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx)); + end loop; + end; + + end if; + + else + -- Generate an Action to check that the bounds of the + -- source value are within the constraints imposed by the + -- target type for a conversion to an unconstrained type. + -- Rule is 4.6(38). + + if Nkind (Parent (Ck_Node)) = N_Type_Conversion then + declare + Opnd_Index : Node_Id; + Targ_Index : Node_Id; + + begin + Opnd_Index + := First_Index (Get_Actual_Subtype (Ck_Node)); + Targ_Index := First_Index (T_Typ); + + while Opnd_Index /= Empty loop + if Nkind (Opnd_Index) = N_Range then + if Is_In_Range + (Low_Bound (Opnd_Index), Etype (Targ_Index)) + and then + Is_In_Range + (High_Bound (Opnd_Index), Etype (Targ_Index)) + then + null; + + elsif Is_Out_Of_Range + (Low_Bound (Opnd_Index), Etype (Targ_Index)) + or else + Is_Out_Of_Range + (High_Bound (Opnd_Index), Etype (Targ_Index)) + then + Add_Check + (Compile_Time_Constraint_Error + (Wnode, "value out of range of}?", T_Typ)); + + else + Evolve_Or_Else + (Cond, + Discrete_Range_Cond + (Opnd_Index, Etype (Targ_Index))); + end if; + end if; + + Next_Index (Opnd_Index); + Next_Index (Targ_Index); + end loop; + end; + end if; + end if; + end if; + + -- Construct the test and insert into the tree + + if Present (Cond) then + if Do_Access then + Cond := Guard_Access (Cond, Loc, Ck_Node); + end if; + + Add_Check (Make_Raise_Constraint_Error (Loc, Condition => Cond)); + end if; + + return Ret_Result; + + end Selected_Range_Checks; + + ------------------------------- + -- Storage_Checks_Suppressed -- + ------------------------------- + + function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Storage_Checks + or else (Present (E) and then Suppress_Storage_Checks (E)); + end Storage_Checks_Suppressed; + + --------------------------- + -- Tag_Checks_Suppressed -- + --------------------------- + + function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is + begin + return Scope_Suppress.Tag_Checks + or else (Present (E) and then Suppress_Tag_Checks (E)); + end Tag_Checks_Suppressed; + +end Checks; |