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------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- C H E C K S -- -- -- -- B o d y -- -- -- -- Copyright (C) 1992-2011, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING3. If not, go to -- -- http://www.gnu.org/licenses for a complete copy of the license. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ with Atree; use Atree; with Debug; use Debug; with Einfo; use Einfo; with Errout; use Errout; with Exp_Ch2; use Exp_Ch2; with Exp_Ch4; use Exp_Ch4; with Exp_Ch11; use Exp_Ch11; with Exp_Pakd; use Exp_Pakd; with Exp_Util; use Exp_Util; with Elists; use Elists; with Eval_Fat; use Eval_Fat; with Freeze; use Freeze; with Lib; use Lib; with Nlists; use Nlists; with Nmake; use Nmake; with Opt; use Opt; with Output; use Output; with Restrict; use Restrict; with Rident; use Rident; with Rtsfind; use Rtsfind; with Sem; use Sem; with Sem_Aux; use Sem_Aux; with Sem_Eval; use Sem_Eval; with Sem_Ch3; use Sem_Ch3; with Sem_Ch8; use Sem_Ch8; with Sem_Res; use Sem_Res; with Sem_Util; use Sem_Util; with Sem_Warn; use Sem_Warn; with Sinfo; use Sinfo; with Sinput; use Sinput; with Snames; use Snames; with Sprint; use Sprint; with Stand; use Stand; with Targparm; use Targparm; 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. ------------------------------------- -- Suppression of Redundant Checks -- ------------------------------------- -- This unit implements a limited circuit for removal of redundant -- checks. The processing is based on a tracing of simple sequential -- flow. For any sequence of statements, we save expressions that are -- marked to be checked, and then if the same expression appears later -- with the same check, then under certain circumstances, the second -- check can be suppressed. -- Basically, we can suppress the check if we know for certain that -- the previous expression has been elaborated (together with its -- check), and we know that the exception frame is the same, and that -- nothing has happened to change the result of the exception. -- Let us examine each of these three conditions in turn to describe -- how we ensure that this condition is met. -- First, we need to know for certain that the previous expression has -- been executed. This is done principally by the mechanism of calling -- Conditional_Statements_Begin at the start of any statement sequence -- and Conditional_Statements_End at the end. The End call causes all -- checks remembered since the Begin call to be discarded. This does -- miss a few cases, notably the case of a nested BEGIN-END block with -- no exception handlers. But the important thing is to be conservative. -- The other protection is that all checks are discarded if a label -- is encountered, since then the assumption of sequential execution -- is violated, and we don't know enough about the flow. -- Second, we need to know that the exception frame is the same. We -- do this by killing all remembered checks when we enter a new frame. -- Again, that's over-conservative, but generally the cases we can help -- with are pretty local anyway (like the body of a loop for example). -- Third, we must be sure to forget any checks which are no longer valid. -- This is done by two mechanisms, first the Kill_Checks_Variable call is -- used to note any changes to local variables. We only attempt to deal -- with checks involving local variables, so we do not need to worry -- about global variables. Second, a call to any non-global procedure -- causes us to abandon all stored checks, since such a all may affect -- the values of any local variables. -- The following define the data structures used to deal with remembering -- checks so that redundant checks can be eliminated as described above. -- Right now, the only expressions that we deal with are of the form of -- simple local objects (either declared locally, or IN parameters) or -- such objects plus/minus a compile time known constant. We can do -- more later on if it seems worthwhile, but this catches many simple -- cases in practice. -- The following record type reflects a single saved check. An entry -- is made in the stack of saved checks if and only if the expression -- has been elaborated with the indicated checks. type Saved_Check is record Killed : Boolean; -- Set True if entry is killed by Kill_Checks Entity : Entity_Id; -- The entity involved in the expression that is checked Offset : Uint; -- A compile time value indicating the result of adding or -- subtracting a compile time value. This value is to be -- added to the value of the Entity. A value of zero is -- used for the case of a simple entity reference. Check_Type : Character; -- This is set to 'R' for a range check (in which case Target_Type -- is set to the target type for the range check) or to 'O' for an -- overflow check (in which case Target_Type is set to Empty). Target_Type : Entity_Id; -- Used only if Do_Range_Check is set. Records the target type for -- the check. We need this, because a check is a duplicate only if -- it has the same target type (or more accurately one with a -- range that is smaller or equal to the stored target type of a -- saved check). end record; -- The following table keeps track of saved checks. Rather than use an -- extensible table. We just use a table of fixed size, and we discard -- any saved checks that do not fit. That's very unlikely to happen and -- this is only an optimization in any case. Saved_Checks : array (Int range 1 .. 200) of Saved_Check; -- Array of saved checks Num_Saved_Checks : Nat := 0; -- Number of saved checks -- The following stack keeps track of statement ranges. It is treated -- as a stack. When Conditional_Statements_Begin is called, an entry -- is pushed onto this stack containing the value of Num_Saved_Checks -- at the time of the call. Then when Conditional_Statements_End is -- called, this value is popped off and used to reset Num_Saved_Checks. -- Note: again, this is a fixed length stack with a size that should -- always be fine. If the value of the stack pointer goes above the -- limit, then we just forget all saved checks. Saved_Checks_Stack : array (Int range 1 .. 100) of Nat; Saved_Checks_TOS : Nat := 0; ----------------------- -- Local Subprograms -- ----------------------- procedure Apply_Float_Conversion_Check (Ck_Node : Node_Id; Target_Typ : Entity_Id); -- The checks on a conversion from a floating-point type to an integer -- type are delicate. They have to be performed before conversion, they -- have to raise an exception when the operand is a NaN, and rounding must -- be taken into account to determine the safe bounds of the operand. 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. type Check_Type is new Check_Id range Access_Check .. Division_Check; function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean; -- This function is used to see if an access or division by zero check is -- needed. The check is to be applied to a single variable appearing in the -- source, and N is the node for the reference. If N is not of this form, -- True is returned with no further processing. If N is of the right form, -- then further processing determines if the given Check is needed. -- -- The particular circuit is to see if we have the case of a check that is -- not needed because it appears in the right operand of a short circuited -- conditional where the left operand guards the check. For example: -- -- if Var = 0 or else Q / Var > 12 then -- ... -- end if; -- -- In this example, the division check is not required. At the same time -- we can issue warnings for suspicious use of non-short-circuited forms, -- such as: -- -- if Var = 0 or Q / Var > 12 then -- ... -- end if; procedure Find_Check (Expr : Node_Id; Check_Type : Character; Target_Type : Entity_Id; Entry_OK : out Boolean; Check_Num : out Nat; Ent : out Entity_Id; Ofs : out Uint); -- This routine is used by Enable_Range_Check and Enable_Overflow_Check -- to see if a check is of the form for optimization, and if so, to see -- if it has already been performed. Expr is the expression to check, -- and Check_Type is 'R' for a range check, 'O' for an overflow check. -- Target_Type is the target type for a range check, and Empty for an -- overflow check. If the entry is not of the form for optimization, -- then Entry_OK is set to False, and the remaining out parameters -- are undefined. If the entry is OK, then Ent/Ofs are set to the -- entity and offset from the expression. Check_Num is the number of -- a matching saved entry in Saved_Checks, or zero if no such entry -- is located. 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. -- This function is called whenever the bound is an entity and the scope -- indicates a protected operation. If the bound is an in-parameter of -- a protected operation that is not a prival, the function returns the -- bound itself. -- 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 Range_Or_Validity_Checks_Suppressed (Expr : Node_Id) return Boolean; -- Returns True if either range or validity checks or both are suppressed -- for the type of the given expression, or, if the expression is the name -- of an entity, if these checks are suppressed for the entity. 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 if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Access_Check); else return Scope_Suppress (Access_Check); end if; end Access_Checks_Suppressed; ------------------------------------- -- Accessibility_Checks_Suppressed -- ------------------------------------- function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Accessibility_Check); else return Scope_Suppress (Accessibility_Check); end if; end Accessibility_Checks_Suppressed; ----------------------------- -- Activate_Division_Check -- ----------------------------- procedure Activate_Division_Check (N : Node_Id) is begin Set_Do_Division_Check (N, True); Possible_Local_Raise (N, Standard_Constraint_Error); end Activate_Division_Check; ----------------------------- -- Activate_Overflow_Check -- ----------------------------- procedure Activate_Overflow_Check (N : Node_Id) is begin Set_Do_Overflow_Check (N, True); Possible_Local_Raise (N, Standard_Constraint_Error); end Activate_Overflow_Check; -------------------------- -- Activate_Range_Check -- -------------------------- procedure Activate_Range_Check (N : Node_Id) is begin Set_Do_Range_Check (N, True); Possible_Local_Raise (N, Standard_Constraint_Error); end Activate_Range_Check; --------------------------------- -- Alignment_Checks_Suppressed -- --------------------------------- function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Alignment_Check); else return Scope_Suppress (Alignment_Check); end if; end Alignment_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 : constant Node_Id := Flag_Node; Internal_Static_Sloc : constant 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, Reason => CE_Range_Check_Failed)); 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 -- We do not need checks if we are not generating code (i.e. the -- expander is not active). This is not just an optimization, there -- are cases (e.g. with pragma Debug) where generating the checks -- can cause real trouble). if not Full_Expander_Active then return; end if; -- No check if short circuiting makes check unnecessary if not Check_Needed (P, Access_Check) then return; end if; -- No check if accessing the Offset_To_Top component of a dispatch -- table. They are safe by construction. if Tagged_Type_Expansion and then Present (Etype (P)) and then RTU_Loaded (Ada_Tags) and then RTE_Available (RE_Offset_To_Top_Ptr) and then Etype (P) = RTE (RE_Offset_To_Top_Ptr) then return; end if; -- Otherwise go ahead and install the check Install_Null_Excluding_Check (P); end Apply_Access_Check; ------------------------------- -- Apply_Accessibility_Check -- ------------------------------- procedure Apply_Accessibility_Check (N : Node_Id; Typ : Entity_Id; Insert_Node : Node_Id) is Loc : constant Source_Ptr := Sloc (N); Param_Ent : Entity_Id := Param_Entity (N); Param_Level : Node_Id; Type_Level : Node_Id; begin if Ada_Version >= Ada_2012 and then not Present (Param_Ent) and then Is_Entity_Name (N) and then Ekind_In (Entity (N), E_Constant, E_Variable) and then Present (Effective_Extra_Accessibility (Entity (N))) then Param_Ent := Entity (N); while Present (Renamed_Object (Param_Ent)) loop -- Renamed_Object must return an Entity_Name here -- because of preceding "Present (E_E_A (...))" test. Param_Ent := Entity (Renamed_Object (Param_Ent)); end loop; end if; 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, and -- accessibility checks are not suppressed. elsif Present (Param_Ent) and then Present (Extra_Accessibility (Param_Ent)) and then UI_Gt (Object_Access_Level (N), Deepest_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, Deepest_Type_Access_Level (Typ)); -- Raise Program_Error if the accessibility level of the access -- parameter is deeper than the level of the target access type. Insert_Action (Insert_Node, Make_Raise_Program_Error (Loc, Condition => Make_Op_Gt (Loc, Left_Opnd => Param_Level, Right_Opnd => Type_Level), Reason => PE_Accessibility_Check_Failed)); Analyze_And_Resolve (N); end if; end Apply_Accessibility_Check; -------------------------------- -- Apply_Address_Clause_Check -- -------------------------------- procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is AC : constant Node_Id := Address_Clause (E); Loc : constant Source_Ptr := Sloc (AC); Typ : constant Entity_Id := Etype (E); Aexp : constant Node_Id := Expression (AC); Expr : Node_Id; -- Address expression (not necessarily the same as Aexp, for example -- when Aexp is a reference to a constant, in which case Expr gets -- reset to reference the value expression of the constant. procedure Compile_Time_Bad_Alignment; -- Post error warnings when alignment is known to be incompatible. Note -- that we do not go as far as inserting a raise of Program_Error since -- this is an erroneous case, and it may happen that we are lucky and an -- underaligned address turns out to be OK after all. -------------------------------- -- Compile_Time_Bad_Alignment -- -------------------------------- procedure Compile_Time_Bad_Alignment is begin if Address_Clause_Overlay_Warnings then Error_Msg_FE ("?specified address for& may be inconsistent with alignment ", Aexp, E); Error_Msg_FE ("\?program execution may be erroneous (RM 13.3(27))", Aexp, E); Set_Address_Warning_Posted (AC); end if; end Compile_Time_Bad_Alignment; -- Start of processing for Apply_Address_Clause_Check begin -- See if alignment check needed. Note that we never need a check if the -- maximum alignment is one, since the check will always succeed. -- Note: we do not check for checks suppressed here, since that check -- was done in Sem_Ch13 when the address clause was processed. We are -- only called if checks were not suppressed. The reason for this is -- that we have to delay the call to Apply_Alignment_Check till freeze -- time (so that all types etc are elaborated), but we have to check -- the status of check suppressing at the point of the address clause. if No (AC) or else not Check_Address_Alignment (AC) or else Maximum_Alignment = 1 then return; end if; -- Obtain expression from address clause Expr := Expression (AC); -- The following loop digs for the real expression to use in the check loop -- For constant, get constant expression if Is_Entity_Name (Expr) and then Ekind (Entity (Expr)) = E_Constant then Expr := Constant_Value (Entity (Expr)); -- For unchecked conversion, get result to convert elsif Nkind (Expr) = N_Unchecked_Type_Conversion then Expr := Expression (Expr); -- For (common case) of To_Address call, get argument elsif Nkind (Expr) = N_Function_Call and then Is_Entity_Name (Name (Expr)) and then Is_RTE (Entity (Name (Expr)), RE_To_Address) then Expr := First (Parameter_Associations (Expr)); if Nkind (Expr) = N_Parameter_Association then Expr := Explicit_Actual_Parameter (Expr); end if; -- We finally have the real expression else exit; end if; end loop; -- See if we know that Expr has a bad alignment at compile time if Compile_Time_Known_Value (Expr) and then (Known_Alignment (E) or else Known_Alignment (Typ)) then declare AL : Uint := Alignment (Typ); begin -- The object alignment might be more restrictive than the -- type alignment. if Known_Alignment (E) then AL := Alignment (E); end if; if Expr_Value (Expr) mod AL /= 0 then Compile_Time_Bad_Alignment; else return; end if; end; -- If the expression has the form X'Address, then we can find out if -- the object X has an alignment that is compatible with the object E. -- If it hasn't or we don't know, we defer issuing the warning until -- the end of the compilation to take into account back end annotations. elsif Nkind (Expr) = N_Attribute_Reference and then Attribute_Name (Expr) = Name_Address and then Has_Compatible_Alignment (E, Prefix (Expr)) = Known_Compatible then return; end if; -- Here we do not know if the value is acceptable. Strictly we don't -- have to do anything, since if the alignment is bad, we have an -- erroneous program. However we are allowed to check for erroneous -- conditions and we decide to do this by default if the check is not -- suppressed. -- However, don't do the check if elaboration code is unwanted if Restriction_Active (No_Elaboration_Code) then return; -- Generate a check to raise PE if alignment may be inappropriate else -- If the original expression is a non-static constant, use the -- name of the constant itself rather than duplicating its -- defining expression, which was extracted above. -- Note: Expr is empty if the address-clause is applied to in-mode -- actuals (allowed by 13.1(22)). if not Present (Expr) or else (Is_Entity_Name (Expression (AC)) and then Ekind (Entity (Expression (AC))) = E_Constant and then Nkind (Parent (Entity (Expression (AC)))) = N_Object_Declaration) then Expr := New_Copy_Tree (Expression (AC)); else Remove_Side_Effects (Expr); end if; Insert_After_And_Analyze (N, Make_Raise_Program_Error (Loc, Condition => Make_Op_Ne (Loc, Left_Opnd => Make_Op_Mod (Loc, Left_Opnd => Unchecked_Convert_To (RTE (RE_Integer_Address), Expr), Right_Opnd => Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (E, Loc), Attribute_Name => Name_Alignment)), Right_Opnd => Make_Integer_Literal (Loc, Uint_0)), Reason => PE_Misaligned_Address_Value), Suppress => All_Checks); return; end if; exception -- If we have some missing run time component in configurable run time -- mode then just skip the check (it is not required in any case). when RE_Not_Available => return; end Apply_Address_Clause_Check; ------------------------------------- -- Apply_Arithmetic_Overflow_Check -- ------------------------------------- -- This routine is called only if the type is an integer type, and a -- software arithmetic overflow check may be needed for op (add, subtract, -- or multiply). This 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); begin -- An interesting special case. If the arithmetic operation appears as -- the operand of a type conversion: -- type1 (x op y) -- and all the following conditions apply: -- arithmetic operation is for a signed integer type -- target type type1 is a static integer subtype -- range of x and y are both included in the range of type1 -- range of x op y is included in the range of type1 -- size of type1 is at least twice the result size of op -- then we don't do an overflow check in any case, instead we transform -- the operation so that we end up with: -- type1 (type1 (x) op type1 (y)) -- This avoids intermediate overflow before the conversion. It is -- explicitly permitted by RM 3.5.4(24): -- For the execution of a predefined operation of a signed integer -- type, the implementation need not raise Constraint_Error if the -- result is outside the base range of the type, so long as the -- correct result is produced. -- It's hard to imagine that any programmer counts on the exception -- being raised in this case, and in any case it's wrong coding to -- have this expectation, given the RM permission. Furthermore, other -- Ada compilers do allow such out of range results. -- Note that we do this transformation even if overflow checking is -- off, since this is precisely about giving the "right" result and -- avoiding the need for an overflow check. -- Note: this circuit is partially redundant with respect to the similar -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals -- with cases that do not come through here. We still need the following -- processing even with the Exp_Ch4 code in place, since we want to be -- sure not to generate the arithmetic overflow check in these cases -- (Exp_Ch4 would have a hard time removing them once generated). if Is_Signed_Integer_Type (Typ) and then Nkind (Parent (N)) = N_Type_Conversion then declare Target_Type : constant Entity_Id := Base_Type (Entity (Subtype_Mark (Parent (N)))); Llo, Lhi : Uint; Rlo, Rhi : Uint; LOK, ROK : Boolean; Vlo : Uint; Vhi : Uint; VOK : Boolean; Tlo : Uint; Thi : Uint; begin if Is_Integer_Type (Target_Type) and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp) then Tlo := Expr_Value (Type_Low_Bound (Target_Type)); Thi := Expr_Value (Type_High_Bound (Target_Type)); Determine_Range (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True); Determine_Range (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True); if (LOK and ROK) and then Tlo <= Llo and then Lhi <= Thi and then Tlo <= Rlo and then Rhi <= Thi then Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True); if VOK and then Tlo <= Vlo and then Vhi <= Thi then Rewrite (Left_Opnd (N), Make_Type_Conversion (Loc, Subtype_Mark => New_Occurrence_Of (Target_Type, Loc), Expression => Relocate_Node (Left_Opnd (N)))); Rewrite (Right_Opnd (N), Make_Type_Conversion (Loc, Subtype_Mark => New_Occurrence_Of (Target_Type, Loc), Expression => Relocate_Node (Right_Opnd (N)))); -- Rewrite the conversion operand so that the original -- node is retained, in order to avoid the warning for -- redundant conversions in Resolve_Type_Conversion. Rewrite (N, Relocate_Node (N)); Set_Etype (N, Target_Type); Analyze_And_Resolve (Left_Opnd (N), Target_Type); Analyze_And_Resolve (Right_Opnd (N), Target_Type); -- Given that the target type is twice the size of the -- source type, overflow is now impossible, so we can -- safely kill the overflow check and return. Set_Do_Overflow_Check (N, False); return; end if; end if; end if; end; end if; -- Now see if an overflow check is required declare 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; begin -- Skip check if back end does overflow checks, or the overflow flag -- is not set anyway, or we are not doing code expansion, or the -- parent node is a type conversion whose operand is an arithmetic -- operation on signed integers on which the expander can promote -- later the operands to type Integer (see Expand_N_Type_Conversion). -- Special case CLI target, where arithmetic overflow checks can be -- performed for integer and long_integer if Backend_Overflow_Checks_On_Target or else not Do_Overflow_Check (N) or else not Full_Expander_Active or else (Present (Parent (N)) and then Nkind (Parent (N)) = N_Type_Conversion and then Integer_Promotion_Possible (Parent (N))) or else (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size) then return; end if; -- Otherwise, generate the full general code for front end overflow -- detection, which works by doing arithmetic in a larger type: -- 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. -- If the size of 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); -- In the discrete type case, we directly generate the range check -- for the outer operand. This range check will implement the -- required overflow check. if Is_Discrete_Type (Typ) then Rewrite (N, Opnd); Generate_Range_Check (Expression (N), Typ, CE_Overflow_Check_Failed); -- For other types, we enable overflow checking on the conversion, -- after setting the node as analyzed to prevent recursive attempts -- to expand the conversion node. else Set_Analyzed (Opnd, True); Enable_Overflow_Check (Opnd); Rewrite (N, Opnd); end if; exception when RE_Not_Available => return; end; end Apply_Arithmetic_Overflow_Check; ---------------------------- -- Apply_Constraint_Check -- ---------------------------- procedure Apply_Constraint_Check (N : Node_Id; Typ : Entity_Id; No_Sliding : Boolean := False) is Desig_Typ : Entity_Id; begin -- No checks inside a generic (check the instantiations) if Inside_A_Generic then return; end if; -- Apply required constraint checks if Is_Scalar_Type (Typ) then Apply_Scalar_Range_Check (N, Typ); elsif Is_Array_Type (Typ) then -- A useful optimization: an aggregate with only an others clause -- always has the right bounds. if Nkind (N) = N_Aggregate and then No (Expressions (N)) and then Nkind (First (Choices (First (Component_Associations (N))))) = N_Others_Choice then return; end if; 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 Known_Null (N) then if Can_Never_Be_Null (Typ) then Install_Null_Excluding_Check (N); end if; -- 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; -- Apply the 2005 Null_Excluding check. Note that we do not apply -- this check if the constraint node is illegal, as shown by having -- an error posted. This additional guard prevents cascaded errors -- and compiler aborts on illegal programs involving Ada 2005 checks. if Can_Never_Be_Null (Typ) and then not Can_Never_Be_Null (Etype (N)) and then not Error_Posted (N) then Install_Null_Excluding_Check (N); 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 Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean; -- A heap object with an indefinite subtype is constrained by its -- initial value, and assigning to it requires a constraint_check. -- The target may be an explicit dereference, or a renaming of one. 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. ---------------------------------- -- Denotes_Explicit_Dereference -- ---------------------------------- function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is begin return Nkind (Obj) = N_Explicit_Dereference or else (Is_Entity_Name (Obj) and then Present (Renamed_Object (Entity (Obj))) and then Nkind (Renamed_Object (Entity (Obj))) = N_Explicit_Dereference); end Denotes_Explicit_Dereference; ---------------------------------------- -- 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 Full_Expander_Active or else Discriminant_Checks_Suppressed (T_Typ) then return; end if; -- No discriminant checks necessary for an access when expression is -- statically Null. This is not only an optimization, it is fundamental -- because otherwise discriminant checks may be generated in init procs -- for types containing an access to a not-yet-frozen 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 Known_Null (N) 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. -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual -- subtype to the parameter and dereference cases, since other aliased -- objects are unconstrained (unless the nominal subtype is explicitly -- constrained). if Present (Lhs) and then (Present (Param_Entity (Lhs)) or else (Ada_Version < Ada_2005 and then not Is_Constrained (T_Typ) and then Is_Aliased_View (Lhs) and then not Is_Aliased_Unconstrained_Component) or else (Ada_Version >= Ada_2005 and then not Is_Constrained (T_Typ) and then Denotes_Explicit_Dereference (Lhs) and then Nkind (Original_Node (Lhs)) /= N_Function_Call)) 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; -- Ada 2005: nothing to do if the type is one for which there is a -- partial view that is constrained. elsif Ada_Version >= Ada_2005 and then Effectively_Has_Constrained_Partial_View (Typ => Base_Type (T_Typ), Scop => Current_Scope) then return; end if; -- Nothing to do if the type is an Unchecked_Union if Is_Unchecked_Union (Base_Type (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 No (Param_Entity (Lhs))) 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 : constant 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; -- A further optimization: if T_Typ is derived from S_Typ -- without imposing a constraint, no check is needed. if Nkind (Original_Node (Parent (T_Typ))) = N_Full_Type_Declaration then declare Type_Def : constant Node_Id := Type_Definition (Original_Node (Parent (T_Typ))); begin if Nkind (Type_Def) = N_Derived_Type_Definition and then Is_Entity_Name (Subtype_Indication (Type_Def)) and then Entity (Subtype_Indication (Type_Def)) = S_Typ then return; end if; end; end if; end if; DconT := First_Elmt (Discriminant_Constraint (T_Typ)); while Present (Discr) loop ItemS := Node (DconS); ItemT := Node (DconT); -- For a discriminated component type constrained by the -- current instance of an enclosing type, there is no -- applicable discriminant check. if Nkind (ItemT) = N_Attribute_Reference and then Is_Access_Type (Etype (ItemT)) and then Is_Entity_Name (Prefix (ItemT)) and then Is_Type (Entity (Prefix (ItemT))) then return; end if; -- If the expressions for the discriminants are identical -- and it is side-effect free (for now just an entity), -- this may be a shared constraint, e.g. from a subtype -- without a constraint introduced as a generic actual. -- Examine other discriminants if any. if ItemS = ItemT and then Is_Entity_Name (ItemS) then null; elsif not Is_OK_Static_Expression (ItemS) or else not Is_OK_Static_Expression (ItemT) then exit; elsif 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&?", CE_Discriminant_Check_Failed, 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, Reason => CE_Discriminant_Check_Failed)); 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; pragma Warnings (Off, Lhi); -- Don't actually use this value begin if Full_Expander_Active and then not Backend_Divide_Checks_On_Target and then Check_Needed (Right, Division_Check) then Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True); -- 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_Move_Checks (Right), Right_Opnd => Make_Integer_Literal (Loc, 0)), Reason => CE_Divide_By_Zero)); 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, Assume_Valid => True); 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_Move_Checks (Left), Right_Opnd => Make_Integer_Literal (Loc, LLB)), Make_Op_Eq (Loc, Left_Opnd => Duplicate_Subexpr (Right), Right_Opnd => Make_Integer_Literal (Loc, -1))), Reason => CE_Overflow_Check_Failed)); end if; end if; end if; end if; end Apply_Divide_Check; ---------------------------------- -- Apply_Float_Conversion_Check -- ---------------------------------- -- Let F and I be the source and target types of the conversion. The RM -- specifies that a floating-point value X is rounded to the nearest -- integer, with halfway cases being rounded away from zero. The rounded -- value of X is checked against I'Range. -- The catch in the above paragraph is that there is no good way to know -- whether the round-to-integer operation resulted in overflow. A remedy is -- to perform a range check in the floating-point domain instead, however: -- (1) The bounds may not be known at compile time -- (2) The check must take into account rounding or truncation. -- (3) The range of type I may not be exactly representable in F. -- (4) For the rounding case, The end-points I'First - 0.5 and -- I'Last + 0.5 may or may not be in range, depending on the -- sign of I'First and I'Last. -- (5) X may be a NaN, which will fail any comparison -- The following steps correctly convert X with rounding: -- (1) If either I'First or I'Last is not known at compile time, use -- I'Base instead of I in the next three steps and perform a -- regular range check against I'Range after conversion. -- (2) If I'First - 0.5 is representable in F then let Lo be that -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First). -- In other words, take one of the closest floating-point numbers -- (which is an integer value) to I'First, and see if it is in -- range or not. -- (3) If I'Last + 0.5 is representable in F then let Hi be that value -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last). -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo) -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi) -- For the truncating case, replace steps (2) and (3) as follows: -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let -- Lo_OK be True. -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let -- Hi_OK be True. procedure Apply_Float_Conversion_Check (Ck_Node : Node_Id; Target_Typ : Entity_Id) is LB : constant Node_Id := Type_Low_Bound (Target_Typ); HB : constant Node_Id := Type_High_Bound (Target_Typ); Loc : constant Source_Ptr := Sloc (Ck_Node); Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node)); Target_Base : constant Entity_Id := Implementation_Base_Type (Target_Typ); Par : constant Node_Id := Parent (Ck_Node); pragma Assert (Nkind (Par) = N_Type_Conversion); -- Parent of check node, must be a type conversion Truncate : constant Boolean := Float_Truncate (Par); Max_Bound : constant Uint := UI_Expon (Machine_Radix_Value (Expr_Type), Machine_Mantissa_Value (Expr_Type) - 1) - 1; -- Largest bound, so bound plus or minus half is a machine number of F Ifirst, Ilast : Uint; -- Bounds of integer type Lo, Hi : Ureal; -- Bounds to check in floating-point domain Lo_OK, Hi_OK : Boolean; -- True iff Lo resp. Hi belongs to I'Range Lo_Chk, Hi_Chk : Node_Id; -- Expressions that are False iff check fails Reason : RT_Exception_Code; begin if not Compile_Time_Known_Value (LB) or not Compile_Time_Known_Value (HB) then declare -- First check that the value falls in the range of the base type, -- to prevent overflow during conversion and then perform a -- regular range check against the (dynamic) bounds. pragma Assert (Target_Base /= Target_Typ); Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par); begin Apply_Float_Conversion_Check (Ck_Node, Target_Base); Set_Etype (Temp, Target_Base); Insert_Action (Parent (Par), Make_Object_Declaration (Loc, Defining_Identifier => Temp, Object_Definition => New_Occurrence_Of (Target_Typ, Loc), Expression => New_Copy_Tree (Par)), Suppress => All_Checks); Insert_Action (Par, Make_Raise_Constraint_Error (Loc, Condition => Make_Not_In (Loc, Left_Opnd => New_Occurrence_Of (Temp, Loc), Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)), Reason => CE_Range_Check_Failed)); Rewrite (Par, New_Occurrence_Of (Temp, Loc)); return; end; end if; -- Get the (static) bounds of the target type Ifirst := Expr_Value (LB); Ilast := Expr_Value (HB); -- A simple optimization: if the expression is a universal literal, -- we can do the comparison with the bounds and the conversion to -- an integer type statically. The range checks are unchanged. if Nkind (Ck_Node) = N_Real_Literal and then Etype (Ck_Node) = Universal_Real and then Is_Integer_Type (Target_Typ) and then Nkind (Parent (Ck_Node)) = N_Type_Conversion then declare Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node)); begin if Int_Val <= Ilast and then Int_Val >= Ifirst then -- Conversion is safe Rewrite (Parent (Ck_Node), Make_Integer_Literal (Loc, UI_To_Int (Int_Val))); Analyze_And_Resolve (Parent (Ck_Node), Target_Typ); return; end if; end; end if; -- Check against lower bound if Truncate and then Ifirst > 0 then Lo := Pred (Expr_Type, UR_From_Uint (Ifirst)); Lo_OK := False; elsif Truncate then Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1)); Lo_OK := True; elsif abs (Ifirst) < Max_Bound then Lo := UR_From_Uint (Ifirst) - Ureal_Half; Lo_OK := (Ifirst > 0); else Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node); Lo_OK := (Lo >= UR_From_Uint (Ifirst)); end if; if Lo_OK then -- Lo_Chk := (X >= Lo) Lo_Chk := Make_Op_Ge (Loc, Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node), Right_Opnd => Make_Real_Literal (Loc, Lo)); else -- Lo_Chk := (X > Lo) Lo_Chk := Make_Op_Gt (Loc, Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node), Right_Opnd => Make_Real_Literal (Loc, Lo)); end if; -- Check against higher bound if Truncate and then Ilast < 0 then Hi := Succ (Expr_Type, UR_From_Uint (Ilast)); Hi_OK := False; elsif Truncate then Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1)); Hi_OK := True; elsif abs (Ilast) < Max_Bound then Hi := UR_From_Uint (Ilast) + Ureal_Half; Hi_OK := (Ilast < 0); else Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node); Hi_OK := (Hi <= UR_From_Uint (Ilast)); end if; if Hi_OK then -- Hi_Chk := (X <= Hi) Hi_Chk := Make_Op_Le (Loc, Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node), Right_Opnd => Make_Real_Literal (Loc, Hi)); else -- Hi_Chk := (X < Hi) Hi_Chk := Make_Op_Lt (Loc, Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node), Right_Opnd => Make_Real_Literal (Loc, Hi)); end if; -- If the bounds of the target type are the same as those of the base -- type, the check is an overflow check as a range check is not -- performed in these cases. if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast then Reason := CE_Overflow_Check_Failed; else Reason := CE_Range_Check_Failed; end if; -- Raise CE if either conditions does not hold Insert_Action (Ck_Node, Make_Raise_Constraint_Error (Loc, Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)), Reason => Reason)); end Apply_Float_Conversion_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_Predicate_Check -- --------------------------- procedure Apply_Predicate_Check (N : Node_Id; Typ : Entity_Id) is begin if Present (Predicate_Function (Typ)) then Insert_Action (N, Make_Predicate_Check (Typ, Duplicate_Subexpr (N))); end if; end Apply_Predicate_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 --------------- -- Bad_Value -- --------------- procedure Bad_Value is begin Apply_Compile_Time_Constraint_Error (Expr, "value not in range of}?", CE_Range_Check_Failed, Ent => Target_Typ, Typ => Target_Typ); end Bad_Value; -- Start of processing for Apply_Scalar_Range_Check begin -- Return if check obviously not needed if -- Not needed inside generic Inside_A_Generic -- Not needed if previous error or else Target_Typ = Any_Type or else Nkind (Expr) = N_Error -- Not needed for non-scalar type or else not Is_Scalar_Type (Target_Typ) -- Not needed if we know node raises CE already 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); if Is_Access_Type (Arr_Typ) then Arr_Typ := Designated_Type (Arr_Typ); end if; 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 Index_Checks_Suppressed (Base_Type (Arr_Typ)) then return; -- Check array itself if it is an entity name elsif Is_Entity_Name (Arr) and then Index_Checks_Suppressed (Entity (Arr)) then return; -- Check expression itself if it is an entity name elsif Is_Entity_Name (Expr) and then Index_Checks_Suppressed (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 Range_Checks_Suppressed (Base_Type (Target_Typ)) then return; -- Check expression itself if it is an entity name elsif Is_Entity_Name (Expr) and then Range_Checks_Suppressed (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 Range_Checks_Suppressed (Entity (Name (Parnt))) then return; end if; end if; end if; -- Do not set range checks if they are killed if Nkind (Expr) = N_Unchecked_Type_Conversion and then Kill_Range_Check (Expr) then return; end if; -- Do not set range checks for any values from System.Scalar_Values -- since the whole idea of such values is to avoid checking them! if Is_Entity_Name (Expr) and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values) then return; 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. We do not do this if -- range checks are killed. 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. -- We 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 declare Lov : constant Uint := Expr_Value (Tlo); Hiv : constant Uint := Expr_Value (Thi); begin -- If range is null, we for sure have a constraint error -- (we don't even need to look at the value involved, -- since all possible values will raise CE). if Lov > Hiv then Bad_Value; return; end if; -- Otherwise determine range of value Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True); if OK then -- If definitely in range, all OK if Lo >= Lov and then Hi <= Hiv then return; -- If definitely not in range, warn elsif Lov > Hi or else Hiv < Lo then Bad_Value; return; -- Otherwise we don't know else null; end if; end if; end; 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 check is meaningful -- only 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, Assume_Valid => True, Fixed_Int => Fixed_Int, Int_Real => Int_Real)) then return; elsif Is_Out_Of_Range (Expr, Target_Typ, Assume_Valid => True, Fixed_Int => Fixed_Int, Int_Real => Int_Real) then Bad_Value; return; -- In the floating-point case, we only do range checks if the type is -- constrained. We definitely do NOT want range checks for unconstrained -- types, since we want to have infinities elsif Is_Floating_Point_Type (S_Typ) then if Is_Constrained (S_Typ) then Enable_Range_Check (Expr); end if; -- For all other cases we enable a range check unconditionally 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 Full_Expander_Active 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); -- Case where node does not now have a dynamic check if not Has_Dynamic_Length_Check (Ck_Node) then -- If checks are on, just insert the check if Checks_On then Insert_Action (Ck_Node, R_Cno); if not Do_Static then Set_Has_Dynamic_Length_Check (Ck_Node); end if; -- If checks are off, then analyze the length check after -- temporarily attaching it to the tree in case the relevant -- condition can be evaluated at compile time. We still want a -- compile time warning in this case. else Set_Parent (R_Cno, Ck_Node); Analyze (R_Cno); 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}?", CE_Length_Check_Failed, 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 Remove_Warning_Messages (R_Cno); 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 Full_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}?", CE_Range_Check_Failed, 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}?", CE_Range_Check_Failed, 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 Remove_Warning_Messages (R_Cno); 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 := Underlying_Type (Etype (Expr)); -- Note: if Etype (Expr) is a private type without discriminants, its -- full view might have discriminants with defaults, so we need the -- full view here to retrieve the constraints. begin if Inside_A_Generic then return; -- Skip these checks if serious errors detected, there are some nasty -- situations of incomplete trees that blow things up. elsif Serious_Errors_Detected > 0 then return; -- Scalar type conversions of the form Target_Type (Expr) require a -- range check if we cannot be sure that Expr is in the base type of -- Target_Typ and also that Expr is in the range of Target_Typ. These -- are not quite the same condition from an implementation point of -- view, but clearly the second includes the first. 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. Float_To_Int : constant Boolean := Is_Floating_Point_Type (Expr_Type) and then Is_Integer_Type (Target_Type); begin if not Overflow_Checks_Suppressed (Target_Base) and then not In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK) and then not Float_To_Int then Activate_Overflow_Check (N); end if; if not Range_Checks_Suppressed (Target_Type) and then not Range_Checks_Suppressed (Expr_Type) then if Float_To_Int then Apply_Float_Conversion_Check (Expr, Target_Type); else Apply_Scalar_Range_Check (Expr, Target_Type, Fixed_Int => Conv_OK); -- If the target type has predicates, we need to indicate -- the need for a check, even if Determine_Range finds -- that the value is within bounds. This may be the case -- e.g for a division with a constant denominator. if Has_Predicates (Target_Type) then Enable_Range_Check (Expr); end if; end if; end if; end; elsif Comes_From_Source (N) and then not Discriminant_Checks_Suppressed (Target_Type) 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 (Stored_Constraint (Target_Type)) then -- An unconstrained derived type may have inherited discriminant. -- Build an actual discriminant constraint list using the stored -- 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 : constant Elist_Id := New_Elmt_List; Old_Constraints : constant Elist_Id := Discriminant_Constraint (Expr_Type); begin Constraint := First_Elmt (Stored_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 stored discriminants, this will provide the -- required consistency check. Append_Elmt (Make_Selected_Component (Loc, Prefix => Duplicate_Subexpr_No_Checks (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 -- stored discriminant. else Append_Elmt (Duplicate_Subexpr_No_Checks (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, Reason => CE_Discriminant_Check_Failed)); end; -- For arrays, conversions are applied during expansion, to take into -- accounts changes of representation. The checks become range checks on -- the base type or length checks on the subtype, depending on whether -- the target type is unconstrained or constrained. 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; -- If the prefix is a selected component that depends on a discriminant -- the check may improperly expose a discriminant instead of using -- the bounds of the object itself. Set the type of the attribute to -- the base type of the context, so that a check will be imposed when -- needed (e.g. if the node appears as an index). elsif Nkind (Prefix (N)) = N_Selected_Component and then Ekind (Typ) = E_Signed_Integer_Subtype and then Depends_On_Discriminant (Scalar_Range (Typ)) then Set_Etype (N, Base_Type (Typ)); -- 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; ------------------------------------- -- Atomic_Synchronization_Disabled -- ------------------------------------- -- Note: internally Disable/Enable_Atomic_Synchronization is implemented -- using a bogus check called Atomic_Synchronization. This is to make it -- more convenient to get exactly the same semantics as [Un]Suppress. function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is begin -- If debug flag d.e is set, always return False, i.e. all atomic sync -- looks enabled, since it is never disabled. if Debug_Flag_Dot_E then return False; -- If debug flag d.d is set then always return True, i.e. all atomic -- sync looks disabled, since it always tests True. elsif Debug_Flag_Dot_D then return True; -- If entity present, then check result for that entity elsif Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Atomic_Synchronization); -- Otherwise result depends on current scope setting else return Scope_Suppress (Atomic_Synchronization); end if; end Atomic_Synchronization_Disabled; ------------------------------- -- 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; Dref : Node_Id; Dval : Node_Id; function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id; ---------------------------------- -- Aggregate_Discriminant_Value -- ---------------------------------- function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is Assoc : Node_Id; begin -- The aggregate has been normalized with named associations. We use -- the Chars field to locate the discriminant to take into account -- discriminants in derived types, which carry the same name as those -- in the parent. Assoc := First (Component_Associations (N)); while Present (Assoc) loop if Chars (First (Choices (Assoc))) = Chars (Disc) then return Expression (Assoc); else Next (Assoc); end if; end loop; -- Discriminant must have been found in the loop above raise Program_Error; end Aggregate_Discriminant_Val; -- Start of processing for Build_Discriminant_Checks begin -- Loop through discriminants evolving the condition 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_No_Checks (Dval); end if; -- If we have an Unchecked_Union node, we can infer the discriminants -- of the node. if Is_Unchecked_Union (Base_Type (T_Typ)) then Dref := New_Copy ( Get_Discriminant_Value ( First_Discriminant (T_Typ), T_Typ, Stored_Constraint (T_Typ))); elsif Nkind (N) = N_Aggregate then Dref := Duplicate_Subexpr_No_Checks (Aggregate_Discriminant_Val (Disc_Ent)); else Dref := Make_Selected_Component (Loc, Prefix => Duplicate_Subexpr_No_Checks (N, Name_Req => True), Selector_Name => Make_Identifier (Loc, Chars (Disc_Ent))); Set_Is_In_Discriminant_Check (Dref); end if; Evolve_Or_Else (Cond, Make_Op_Ne (Loc, Left_Opnd => Dref, Right_Opnd => Dval)); Next_Elmt (Disc); Next_Discriminant (Disc_Ent); end loop; return Cond; end Build_Discriminant_Checks; ------------------ -- Check_Needed -- ------------------ function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is N : Node_Id; P : Node_Id; K : Node_Kind; L : Node_Id; R : Node_Id; begin -- Always check if not simple entity if Nkind (Nod) not in N_Has_Entity or else not Comes_From_Source (Nod) then return True; end if; -- Look up tree for short circuit N := Nod; loop P := Parent (N); K := Nkind (P); -- Done if out of subexpression (note that we allow generated stuff -- such as itype declarations in this context, to keep the loop going -- since we may well have generated such stuff in complex situations. -- Also done if no parent (probably an error condition, but no point -- in behaving nasty if we find it!) if No (P) or else (K not in N_Subexpr and then Comes_From_Source (P)) then return True; -- Or/Or Else case, where test is part of the right operand, or is -- part of one of the actions associated with the right operand, and -- the left operand is an equality test. elsif K = N_Op_Or then exit when N = Right_Opnd (P) and then Nkind (Left_Opnd (P)) = N_Op_Eq; elsif K = N_Or_Else then exit when (N = Right_Opnd (P) or else (Is_List_Member (N) and then List_Containing (N) = Actions (P))) and then Nkind (Left_Opnd (P)) = N_Op_Eq; -- Similar test for the And/And then case, where the left operand -- is an inequality test. elsif K = N_Op_And then exit when N = Right_Opnd (P) and then Nkind (Left_Opnd (P)) = N_Op_Ne; elsif K = N_And_Then then exit when (N = Right_Opnd (P) or else (Is_List_Member (N) and then List_Containing (N) = Actions (P))) and then Nkind (Left_Opnd (P)) = N_Op_Ne; end if; N := P; end loop; -- If we fall through the loop, then we have a conditional with an -- appropriate test as its left operand. So test further. L := Left_Opnd (P); R := Right_Opnd (L); L := Left_Opnd (L); -- Left operand of test must match original variable if Nkind (L) not in N_Has_Entity or else Entity (L) /= Entity (Nod) then return True; end if; -- Right operand of test must be key value (zero or null) case Check is when Access_Check => if not Known_Null (R) then return True; end if; when Division_Check => if not Compile_Time_Known_Value (R) or else Expr_Value (R) /= Uint_0 then return True; end if; when others => raise Program_Error; end case; -- Here we have the optimizable case, warn if not short-circuited if K = N_Op_And or else K = N_Op_Or then case Check is when Access_Check => Error_Msg_N ("Constraint_Error may be raised (access check)?", Parent (Nod)); when Division_Check => Error_Msg_N ("Constraint_Error may be raised (zero divide)?", Parent (Nod)); when others => raise Program_Error; end case; if K = N_Op_And then Error_Msg_N -- CODEFIX ("use `AND THEN` instead of AND?", P); else Error_Msg_N -- CODEFIX ("use `OR ELSE` instead of OR?", P); end if; -- If not short-circuited, we need the check return True; -- If short-circuited, we can omit the check else return False; end if; end Check_Needed; ----------------------------------- -- 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; ---------------------------------- -- Null_Exclusion_Static_Checks -- ---------------------------------- procedure Null_Exclusion_Static_Checks (N : Node_Id) is Error_Node : Node_Id; Expr : Node_Id; Has_Null : constant Boolean := Has_Null_Exclusion (N); K : constant Node_Kind := Nkind (N); Typ : Entity_Id; begin pragma Assert (K = N_Component_Declaration or else K = N_Discriminant_Specification or else K = N_Function_Specification or else K = N_Object_Declaration or else K = N_Parameter_Specification); if K = N_Function_Specification then Typ := Etype (Defining_Entity (N)); else Typ := Etype (Defining_Identifier (N)); end if; case K is when N_Component_Declaration => if Present (Access_Definition (Component_Definition (N))) then Error_Node := Component_Definition (N); else Error_Node := Subtype_Indication (Component_Definition (N)); end if; when N_Discriminant_Specification => Error_Node := Discriminant_Type (N); when N_Function_Specification => Error_Node := Result_Definition (N); when N_Object_Declaration => Error_Node := Object_Definition (N); when N_Parameter_Specification => Error_Node := Parameter_Type (N); when others => raise Program_Error; end case; if Has_Null then -- Enforce legality rule 3.10 (13): A null exclusion can only be -- applied to an access [sub]type. if not Is_Access_Type (Typ) then Error_Msg_N ("`NOT NULL` allowed only for an access type", Error_Node); -- Enforce legality rule RM 3.10(14/1): A null exclusion can only -- be applied to a [sub]type that does not exclude null already. elsif Can_Never_Be_Null (Typ) and then Comes_From_Source (Typ) then Error_Msg_NE ("`NOT NULL` not allowed (& already excludes null)", Error_Node, Typ); end if; end if; -- Check that null-excluding objects are always initialized, except for -- deferred constants, for which the expression will appear in the full -- declaration. if K = N_Object_Declaration and then No (Expression (N)) and then not Constant_Present (N) and then not No_Initialization (N) then -- Add an expression that assigns null. This node is needed by -- Apply_Compile_Time_Constraint_Error, which will replace this with -- a Constraint_Error node. Set_Expression (N, Make_Null (Sloc (N))); Set_Etype (Expression (N), Etype (Defining_Identifier (N))); Apply_Compile_Time_Constraint_Error (N => Expression (N), Msg => "(Ada 2005) null-excluding objects must be initialized?", Reason => CE_Null_Not_Allowed); end if; -- Check that a null-excluding component, formal or object is not being -- assigned a null value. Otherwise generate a warning message and -- replace Expression (N) by an N_Constraint_Error node. if K /= N_Function_Specification then Expr := Expression (N); if Present (Expr) and then Known_Null (Expr) then case K is when N_Component_Declaration | N_Discriminant_Specification => Apply_Compile_Time_Constraint_Error (N => Expr, Msg => "(Ada 2005) null not allowed " & "in null-excluding components?", Reason => CE_Null_Not_Allowed); when N_Object_Declaration => Apply_Compile_Time_Constraint_Error (N => Expr, Msg => "(Ada 2005) null not allowed " & "in null-excluding objects?", Reason => CE_Null_Not_Allowed); when N_Parameter_Specification => Apply_Compile_Time_Constraint_Error (N => Expr, Msg => "(Ada 2005) null not allowed " & "in null-excluding formals?", Reason => CE_Null_Not_Allowed); when others => null; end case; end if; end if; end Null_Exclusion_Static_Checks; ---------------------------------- -- Conditional_Statements_Begin -- ---------------------------------- procedure Conditional_Statements_Begin is begin Saved_Checks_TOS := Saved_Checks_TOS + 1; -- If stack overflows, kill all checks, that way we know to simply reset -- the number of saved checks to zero on return. This should never occur -- in practice. if Saved_Checks_TOS > Saved_Checks_Stack'Last then Kill_All_Checks; -- In the normal case, we just make a new stack entry saving the current -- number of saved checks for a later restore. else Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks; if Debug_Flag_CC then w ("Conditional_Statements_Begin: Num_Saved_Checks = ", Num_Saved_Checks); end if; end if; end Conditional_Statements_Begin; -------------------------------- -- Conditional_Statements_End -- -------------------------------- procedure Conditional_Statements_End is begin pragma Assert (Saved_Checks_TOS > 0); -- If the saved checks stack overflowed, then we killed all checks, so -- setting the number of saved checks back to zero is correct. This -- should never occur in practice. if Saved_Checks_TOS > Saved_Checks_Stack'Last then Num_Saved_Checks := 0; -- In the normal case, restore the number of saved checks from the top -- stack entry. else Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS); if Debug_Flag_CC then w ("Conditional_Statements_End: Num_Saved_Checks = ", Num_Saved_Checks); end if; end if; Saved_Checks_TOS := Saved_Checks_TOS - 1; end Conditional_Statements_End; --------------------- -- Determine_Range -- --------------------- Cache_Size : constant := 2 ** 10; 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_V : array (Cache_Index) of Boolean; 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. The Range_Cache_V array records the -- setting of Assume_Valid for the cache entry. procedure Determine_Range (N : Node_Id; OK : out Boolean; Lo : out Uint; Hi : out Uint; Assume_Valid : Boolean := False) is Typ : Entity_Id := Etype (N); -- Type to use, may get reset to base type for possibly invalid entity Lo_Left : Uint; Hi_Left : Uint; -- Lo and Hi bounds of left operand Lo_Right : Uint; Hi_Right : Uint; -- Lo and Hi bounds of right (or only) operand Bound : Node_Id; -- Temp variable used to hold a bound node Hbound : Uint; -- High bound of base type of expression Lor : Uint; Hir : Uint; -- Refined values for low and high bounds, after tightening OK1 : Boolean; -- Used in lower level calls to indicate if call succeeded Cindex : Cache_Index; -- Used to search cache 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, Assume_Valid); if not OK1 then return False; end if; Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid); return OK1; end OK_Operands; -- Start of processing for Determine_Range begin -- For temporary constants internally generated to remove side effects -- we must use the corresponding expression to determine the range of -- the expression. if Is_Entity_Name (N) and then Nkind (Parent (Entity (N))) = N_Object_Declaration and then Ekind (Entity (N)) = E_Constant and then Is_Internal_Name (Chars (Entity (N))) then Determine_Range (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid); return; end if; -- Prevent junk warnings by initializing range variables Lo := No_Uint; Hi := No_Uint; Lor := No_Uint; Hir := No_Uint; -- If type is not defined, we can't determine its range if No (Typ) -- We don't deal with anything except discrete types or else not Is_Discrete_Type (Typ) -- Ignore type for which an error has been posted, since range in -- this case may well be a bogosity deriving from the error. Also -- ignore if error posted on the reference node. or else Error_Posted (N) or else Error_Posted (Typ) 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 and then Determine_Range_Cache_V (Cindex) = Assume_Valid 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). -- First a check, never try to find the bounds of a generic type, since -- these bounds are always junk values, and it is only valid to look at -- the bounds in an instance. if Is_Generic_Type (Typ) then OK := False; return; end if; -- First step, change to use base type unless we know the value is valid if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N))) or else Assume_No_Invalid_Values or else Assume_Valid then null; else Typ := Underlying_Type (Base_Type (Typ)); end if; -- 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 we figure we can't determine the range (a peculiar case, that -- perhaps cannot happen, but there is no point in bombing in this -- optimization circuit. -- First the low bound 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; -- Now the high bound Bound := Type_High_Bound (Typ); -- We need the high bound of the base type later on, and this should -- always be compile time known. Again, it is not clear that this -- can ever be false, but no point in bombing. if 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; -- If we have a static subtype, then that may have a tighter bound so -- use the upper bound of the subtype instead in this case. if Compile_Time_Known_Value (Bound) then Hi := Expr_Value (Bound); end if; -- We may be able to refine this value in certain situations. If any -- 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, Assume_Valid); -- For unary minus, determine range of operand, and negate it when N_Op_Minus => Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid); 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 and then Lo_Right /= 0 then if Lo_Right > 0 then Lor := Uint_0; Hir := Lo_Right - 1; else -- Lo_Right < 0 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 and then Lo_Right /= 0 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, Assume_Valid); -- 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; -- If the index type is a formal type or derived from -- one, the bounds are not static. if Is_Generic_Type (Root_Type (Etype (Indx))) then OK := False; return; end if; Determine_Range (Type_Low_Bound (Etype (Indx)), OK1, LL, LU, Assume_Valid); if OK1 then Determine_Range (Type_High_Bound (Etype (Indx)), OK1, UL, UU, Assume_Valid); 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 + 1); -- 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 + 1); -- 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, Assume_Valid); -- 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 one of the computed bounds is outside the range of the base type, -- the expression may raise an exception and we had better indicate that -- the evaluation has failed, at least if checks are enabled. if OK1 and then Enable_Overflow_Checks and then not Is_Entity_Name (N) and then (Lor < Lo or else Hir > Hi) then OK := False; return; end if; 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_V (Cindex) := Assume_Valid; 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 unforeseen peculiar -- occurrence. However, this is only an optimization attempt, so there is -- really no point in crashing the compiler. Instead we just decide, too -- bad, we can't figure out 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 if Present (E) then if Is_Unchecked_Union (E) then return True; elsif Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Discriminant_Check); end if; end if; return Scope_Suppress (Discriminant_Check); end Discriminant_Checks_Suppressed; -------------------------------- -- Division_Checks_Suppressed -- -------------------------------- function Division_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Division_Check); else return Scope_Suppress (Division_Check); end if; end Division_Checks_Suppressed; ----------------------------------- -- Elaboration_Checks_Suppressed -- ----------------------------------- function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is begin -- The complication in this routine is that if we are in the dynamic -- model of elaboration, we also check All_Checks, since All_Checks -- does not set Elaboration_Check explicitly. if Present (E) then if Kill_Elaboration_Checks (E) then return True; elsif Checks_May_Be_Suppressed (E) then if Is_Check_Suppressed (E, Elaboration_Check) then return True; elsif Dynamic_Elaboration_Checks then return Is_Check_Suppressed (E, All_Checks); else return False; end if; end if; end if; if Scope_Suppress (Elaboration_Check) then return True; elsif Dynamic_Elaboration_Checks then return Scope_Suppress (All_Checks); else return False; end if; end Elaboration_Checks_Suppressed; --------------------------- -- Enable_Overflow_Check -- --------------------------- procedure Enable_Overflow_Check (N : Node_Id) is Typ : constant Entity_Id := Base_Type (Etype (N)); Chk : Nat; OK : Boolean; Ent : Entity_Id; Ofs : Uint; Lo : Uint; Hi : Uint; begin if Debug_Flag_CC then w ("Enable_Overflow_Check for node ", Int (N)); Write_Str (" Source location = "); wl (Sloc (N)); pg (Union_Id (N)); end if; -- No check if overflow checks suppressed for type of node if Present (Etype (N)) and then Overflow_Checks_Suppressed (Etype (N)) then return; -- Nothing to do for unsigned integer types, which do not overflow elsif Is_Modular_Integer_Type (Typ) then return; -- Nothing to do if the range of the result is known OK. We skip this -- for conversions, since the caller already did the check, and in any -- case the condition for deleting the check for a type conversion is -- different. elsif Nkind (N) /= N_Type_Conversion then Determine_Range (N, OK, Lo, Hi, Assume_Valid => True); -- Note in the test below that we assume that the range is not OK -- 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 as being equal to 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 Determine_Range processing. if OK and then Lo > Expr_Value (Type_Low_Bound (Typ)) and then Hi < Expr_Value (Type_High_Bound (Typ)) then if Debug_Flag_CC then w ("No overflow check required"); end if; return; end if; end if; -- If not in optimizing mode, set flag and we are done. We are also done -- (and just set the flag) if the type is not a discrete type, since it -- is not worth the effort to eliminate checks for other than discrete -- types. In addition, we take this same path if we have stored the -- maximum number of checks possible already (a very unlikely situation, -- but we do not want to blow up!) if Optimization_Level = 0 or else not Is_Discrete_Type (Etype (N)) or else Num_Saved_Checks = Saved_Checks'Last then Activate_Overflow_Check (N); if Debug_Flag_CC then w ("Optimization off"); end if; return; end if; -- Otherwise evaluate and check the expression Find_Check (Expr => N, Check_Type => 'O', Target_Type => Empty, Entry_OK => OK, Check_Num => Chk, Ent => Ent, Ofs => Ofs); if Debug_Flag_CC then w ("Called Find_Check"); w (" OK = ", OK); if OK then w (" Check_Num = ", Chk); w (" Ent = ", Int (Ent)); Write_Str (" Ofs = "); pid (Ofs); end if; end if; -- If check is not of form to optimize, then set flag and we are done if not OK then Activate_Overflow_Check (N); return; end if; -- If check is already performed, then return without setting flag if Chk /= 0 then if Debug_Flag_CC then w ("Check suppressed!"); end if; return; end if; -- Here we will make a new entry for the new check Activate_Overflow_Check (N); Num_Saved_Checks := Num_Saved_Checks + 1; Saved_Checks (Num_Saved_Checks) := (Killed => False, Entity => Ent, Offset => Ofs, Check_Type => 'O', Target_Type => Empty); if Debug_Flag_CC then w ("Make new entry, check number = ", Num_Saved_Checks); w (" Entity = ", Int (Ent)); Write_Str (" Offset = "); pid (Ofs); w (" Check_Type = O"); w (" Target_Type = Empty"); end if; -- If we get an exception, then something went wrong, probably because of -- an error in the structure of the tree due to an incorrect program. Or it -- may be a bug in the optimization circuit. In either case the safest -- thing is simply to set the check flag unconditionally. exception when others => Activate_Overflow_Check (N); if Debug_Flag_CC then w (" exception occurred, overflow flag set"); end if; return; end Enable_Overflow_Check; ------------------------ -- Enable_Range_Check -- ------------------------ procedure Enable_Range_Check (N : Node_Id) is Chk : Nat; OK : Boolean; Ent : Entity_Id; Ofs : Uint; Ttyp : Entity_Id; P : Node_Id; begin -- Return if unchecked type conversion with range check killed. In this -- case we never set the flag (that's what Kill_Range_Check is about!) if Nkind (N) = N_Unchecked_Type_Conversion and then Kill_Range_Check (N) then return; end if; -- Do not set range check flag if parent is assignment statement or -- object declaration with Suppress_Assignment_Checks flag set if Nkind_In (Parent (N), N_Assignment_Statement, N_Object_Declaration) and then Suppress_Assignment_Checks (Parent (N)) then return; end if; -- Check for various cases where we should suppress the range check -- No check if range checks suppressed for type of node if Present (Etype (N)) and then Range_Checks_Suppressed (Etype (N)) then return; -- No check if node is an entity name, and range checks are suppressed -- for this entity, or for the type of this entity. elsif Is_Entity_Name (N) and then (Range_Checks_Suppressed (Entity (N)) or else Range_Checks_Suppressed (Etype (Entity (N)))) then return; -- No checks if index of array, and index checks are suppressed for -- the array object or the type of the array. elsif Nkind (Parent (N)) = N_Indexed_Component then declare Pref : constant Node_Id := Prefix (Parent (N)); begin if Is_Entity_Name (Pref) and then Index_Checks_Suppressed (Entity (Pref)) then return; elsif Index_Checks_Suppressed (Etype (Pref)) then return; end if; end; end if; -- Debug trace output if Debug_Flag_CC then w ("Enable_Range_Check for node ", Int (N)); Write_Str (" Source location = "); wl (Sloc (N)); pg (Union_Id (N)); end if; -- If not in optimizing mode, set flag and we are done. We are also done -- (and just set the flag) if the type is not a discrete type, since it -- is not worth the effort to eliminate checks for other than discrete -- types. In addition, we take this same path if we have stored the -- maximum number of checks possible already (a very unlikely situation, -- but we do not want to blow up!) if Optimization_Level = 0 or else No (Etype (N)) or else not Is_Discrete_Type (Etype (N)) or else Num_Saved_Checks = Saved_Checks'Last then Activate_Range_Check (N); if Debug_Flag_CC then w ("Optimization off"); end if; return; end if; -- Otherwise find out the target type P := Parent (N); -- For assignment, use left side subtype if Nkind (P) = N_Assignment_Statement and then Expression (P) = N then Ttyp := Etype (Name (P)); -- For indexed component, use subscript subtype elsif Nkind (P) = N_Indexed_Component then declare Atyp : Entity_Id; Indx : Node_Id; Subs : Node_Id; begin Atyp := Etype (Prefix (P)); if Is_Access_Type (Atyp) then Atyp := Designated_Type (Atyp); -- If the prefix is an access to an unconstrained array, -- perform check unconditionally: it depends on the bounds of -- an object and we cannot currently recognize whether the test -- may be redundant. if not Is_Constrained (Atyp) then Activate_Range_Check (N); return; end if; -- Ditto if the prefix is an explicit dereference whose designated -- type is unconstrained. elsif Nkind (Prefix (P)) = N_Explicit_Dereference and then not Is_Constrained (Atyp) then Activate_Range_Check (N); return; end if; Indx := First_Index (Atyp); Subs := First (Expressions (P)); loop if Subs = N then Ttyp := Etype (Indx); exit; end if; Next_Index (Indx); Next (Subs); end loop; end; -- For now, ignore all other cases, they are not so interesting else if Debug_Flag_CC then w (" target type not found, flag set"); end if; Activate_Range_Check (N); return; end if; -- Evaluate and check the expression Find_Check (Expr => N, Check_Type => 'R', Target_Type => Ttyp, Entry_OK => OK, Check_Num => Chk, Ent => Ent, Ofs => Ofs); if Debug_Flag_CC then w ("Called Find_Check"); w ("Target_Typ = ", Int (Ttyp)); w (" OK = ", OK); if OK then w (" Check_Num = ", Chk); w (" Ent = ", Int (Ent)); Write_Str (" Ofs = "); pid (Ofs); end if; end if; -- If check is not of form to optimize, then set flag and we are done if not OK then if Debug_Flag_CC then w (" expression not of optimizable type, flag set"); end if; Activate_Range_Check (N); return; end if; -- If check is already performed, then return without setting flag if Chk /= 0 then if Debug_Flag_CC then w ("Check suppressed!"); end if; return; end if; -- Here we will make a new entry for the new check Activate_Range_Check (N); Num_Saved_Checks := Num_Saved_Checks + 1; Saved_Checks (Num_Saved_Checks) := (Killed => False, Entity => Ent, Offset => Ofs, Check_Type => 'R', Target_Type => Ttyp); if Debug_Flag_CC then w ("Make new entry, check number = ", Num_Saved_Checks); w (" Entity = ", Int (Ent)); Write_Str (" Offset = "); pid (Ofs); w (" Check_Type = R"); w (" Target_Type = ", Int (Ttyp)); pg (Union_Id (Ttyp)); end if; -- If we get an exception, then something went wrong, probably because of -- an error in the structure of the tree due to an incorrect program. Or -- it may be a bug in the optimization circuit. In either case the safest -- thing is simply to set the check flag unconditionally. exception when others => Activate_Range_Check (N); if Debug_Flag_CC then w (" exception occurred, range flag set"); end if; return; 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; -- Ignore call if range or validity checks suppressed on entity or type elsif Range_Or_Validity_Checks_Suppressed (Expr) 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. -- In addition, we force a check if Force_Validity_Checks is set elsif not Comes_From_Source (Expr) and then not Force_Validity_Checks 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; -- 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; -- No check on a universal real constant. The context will eventually -- convert it to a machine number for some target type, or report an -- illegality. elsif Nkind (Expr) = N_Real_Literal and then Etype (Expr) = Universal_Real then return; -- If the expression denotes a component of a packed boolean array, -- no possible check applies. We ignore the old ACATS chestnuts that -- involve Boolean range True..True. -- Note: validity checks are generated for expressions that yield a -- scalar type, when it is possible to create a value that is outside of -- the type. If this is a one-bit boolean no such value exists. This is -- an optimization, and it also prevents compiler blowing up during the -- elaboration of improperly expanded packed array references. elsif Nkind (Expr) = N_Indexed_Component and then Is_Bit_Packed_Array (Etype (Prefix (Expr))) and then Root_Type (Etype (Expr)) = Standard_Boolean 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 this is an -- indirect or dispatching call, get signature from the -- subprogram type. if Nkind (P) = N_Procedure_Call_Statement then L := Parameter_Associations (P); if Is_Entity_Name (Name (P)) then E := Entity (Name (P)); else pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference); E := Etype (Name (P)); end if; -- 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 for 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 this is a boolean expression, only its elementary operands need -- checking: if they are valid, a boolean or short-circuit operation -- with them will be valid as well. if Base_Type (Typ) = Standard_Boolean and then (Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit) then return; end if; -- If we fall through, a validity check is required Insert_Valid_Check (Expr); if Is_Entity_Name (Expr) and then Safe_To_Capture_Value (Expr, Entity (Expr)) then Set_Is_Known_Valid (Entity (Expr)); end if; 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 considered 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. Note that even when packed arrays are -- represented using modular types, they are still arrays semantically, -- so they are also always valid (in particular, the unused bits can be -- random rubbish without affecting the validity of the array value). if not Is_Scalar_Type (Typ) or else Is_Packed_Array_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; -- References to discriminants are always considered valid. The value -- of a discriminant gets checked when the object is built. Within the -- record, we consider it valid, and it is important to do so, since -- otherwise we can try to generate bogus validity checks which -- reference discriminants out of scope. Discriminants of concurrent -- types are excluded for the same reason. elsif Is_Entity_Name (Expr) and then Denotes_Discriminant (Expr, Check_Concurrent => True) 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 operator is always considered valid, since we -- assume the necessary checks are done by the operator. For operators -- on floating-point operations, we must also check when the operation -- is the right-hand side of an assignment, or is an actual in a call. elsif Nkind (Expr) in N_Op then if Is_Floating_Point_Type (Typ) and then Validity_Check_Floating_Point and then (Nkind (Parent (Expr)) = N_Assignment_Statement or else Nkind (Parent (Expr)) = N_Function_Call or else Nkind (Parent (Expr)) = N_Parameter_Association) then return False; else return True; end if; -- The result of a membership test is always valid, since it is true or -- false, there are no other possibilities. elsif Nkind (Expr) in N_Membership_Test then return True; -- For all other cases, we do not know the expression is valid else return False; end if; end Expr_Known_Valid; ---------------- -- Find_Check -- ---------------- procedure Find_Check (Expr : Node_Id; Check_Type : Character; Target_Type : Entity_Id; Entry_OK : out Boolean; Check_Num : out Nat; Ent : out Entity_Id; Ofs : out Uint) is function Within_Range_Of (Target_Type : Entity_Id; Check_Type : Entity_Id) return Boolean; -- Given a requirement for checking a range against Target_Type, and -- and a range Check_Type against which a check has already been made, -- determines if the check against check type is sufficient to ensure -- that no check against Target_Type is required. --------------------- -- Within_Range_Of -- --------------------- function Within_Range_Of (Target_Type : Entity_Id; Check_Type : Entity_Id) return Boolean is begin if Target_Type = Check_Type then return True; else declare Tlo : constant Node_Id := Type_Low_Bound (Target_Type); Thi : constant Node_Id := Type_High_Bound (Target_Type); Clo : constant Node_Id := Type_Low_Bound (Check_Type); Chi : constant Node_Id := Type_High_Bound (Check_Type); begin if (Tlo = Clo or else (Compile_Time_Known_Value (Tlo) and then Compile_Time_Known_Value (Clo) and then Expr_Value (Clo) >= Expr_Value (Tlo))) and then (Thi = Chi or else (Compile_Time_Known_Value (Thi) and then Compile_Time_Known_Value (Chi) and then Expr_Value (Chi) <= Expr_Value (Clo))) then return True; else return False; end if; end; end if; end Within_Range_Of; -- Start of processing for Find_Check begin -- Establish default, in case no entry is found Check_Num := 0; -- Case of expression is simple entity reference if Is_Entity_Name (Expr) then Ent := Entity (Expr); Ofs := Uint_0; -- Case of expression is entity + known constant elsif Nkind (Expr) = N_Op_Add and then Compile_Time_Known_Value (Right_Opnd (Expr)) and then Is_Entity_Name (Left_Opnd (Expr)) then Ent := Entity (Left_Opnd (Expr)); Ofs := Expr_Value (Right_Opnd (Expr)); -- Case of expression is entity - known constant elsif Nkind (Expr) = N_Op_Subtract and then Compile_Time_Known_Value (Right_Opnd (Expr)) and then Is_Entity_Name (Left_Opnd (Expr)) then Ent := Entity (Left_Opnd (Expr)); Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr))); -- Any other expression is not of the right form else Ent := Empty; Ofs := Uint_0; Entry_OK := False; return; end if; -- Come here with expression of appropriate form, check if entity is an -- appropriate one for our purposes. if (Ekind (Ent) = E_Variable or else Is_Constant_Object (Ent)) and then not Is_Library_Level_Entity (Ent) then Entry_OK := True; else Entry_OK := False; return; end if; -- See if there is matching check already for J in reverse 1 .. Num_Saved_Checks loop declare SC : Saved_Check renames Saved_Checks (J); begin if SC.Killed = False and then SC.Entity = Ent and then SC.Offset = Ofs and then SC.Check_Type = Check_Type and then Within_Range_Of (Target_Type, SC.Target_Type) then Check_Num := J; return; end if; end; end loop; -- If we fall through entry was not found return; end Find_Check; --------------------------------- -- Generate_Discriminant_Check -- --------------------------------- -- Note: the code for this procedure is derived from the -- Emit_Discriminant_Check Routine in trans.c. procedure Generate_Discriminant_Check (N : Node_Id) is Loc : constant Source_Ptr := Sloc (N); Pref : constant Node_Id := Prefix (N); Sel : constant Node_Id := Selector_Name (N); Orig_Comp : constant Entity_Id := Original_Record_Component (Entity (Sel)); -- The original component to be checked Discr_Fct : constant Entity_Id := Discriminant_Checking_Func (Orig_Comp); -- The discriminant checking function Discr : Entity_Id; -- One discriminant to be checked in the type Real_Discr : Entity_Id; -- Actual discriminant in the call Pref_Type : Entity_Id; -- Type of relevant prefix (ignoring private/access stuff) Args : List_Id; -- List of arguments for function call Formal : Entity_Id; -- Keep track of the formal corresponding to the actual we build for -- each discriminant, in order to be able to perform the necessary type -- conversions. Scomp : Node_Id; -- Selected component reference for checking function argument begin Pref_Type := Etype (Pref); -- Force evaluation of the prefix, so that it does not get evaluated -- twice (once for the check, once for the actual reference). Such a -- double evaluation is always a potential source of inefficiency, -- and is functionally incorrect in the volatile case, or when the -- prefix may have side-effects. An entity or a component of an -- entity requires no evaluation. if Is_Entity_Name (Pref) then if Treat_As_Volatile (Entity (Pref)) then Force_Evaluation (Pref, Name_Req => True); end if; elsif Treat_As_Volatile (Etype (Pref)) then Force_Evaluation (Pref, Name_Req => True); elsif Nkind (Pref) = N_Selected_Component and then Is_Entity_Name (Prefix (Pref)) then null; else Force_Evaluation (Pref, Name_Req => True); end if; -- For a tagged type, use the scope of the original component to -- obtain the type, because ??? if Is_Tagged_Type (Scope (Orig_Comp)) then Pref_Type := Scope (Orig_Comp); -- For an untagged derived type, use the discriminants of the parent -- which have been renamed in the derivation, possibly by a one-to-many -- discriminant constraint. For non-tagged type, initially get the Etype -- of the prefix else if Is_Derived_Type (Pref_Type) and then Number_Discriminants (Pref_Type) /= Number_Discriminants (Etype (Base_Type (Pref_Type))) then Pref_Type := Etype (Base_Type (Pref_Type)); end if; end if; -- We definitely should have a checking function, This routine should -- not be called if no discriminant checking function is present. pragma Assert (Present (Discr_Fct)); -- Create the list of the actual parameters for the call. This list -- is the list of the discriminant fields of the record expression to -- be discriminant checked. Args := New_List; Formal := First_Formal (Discr_Fct); Discr := First_Discriminant (Pref_Type); while Present (Discr) loop -- If we have a corresponding discriminant field, and a parent -- subtype is present, then we want to use the corresponding -- discriminant since this is the one with the useful value. if Present (Corresponding_Discriminant (Discr)) and then Ekind (Pref_Type) = E_Record_Type and then Present (Parent_Subtype (Pref_Type)) then Real_Discr := Corresponding_Discriminant (Discr); else Real_Discr := Discr; end if; -- Construct the reference to the discriminant Scomp := Make_Selected_Component (Loc, Prefix => Unchecked_Convert_To (Pref_Type, Duplicate_Subexpr (Pref)), Selector_Name => New_Occurrence_Of (Real_Discr, Loc)); -- Manually analyze and resolve this selected component. We really -- want it just as it appears above, and do not want the expander -- playing discriminal games etc with this reference. Then we append -- the argument to the list we are gathering. Set_Etype (Scomp, Etype (Real_Discr)); Set_Analyzed (Scomp, True); Append_To (Args, Convert_To (Etype (Formal), Scomp)); Next_Formal_With_Extras (Formal); Next_Discriminant (Discr); end loop; -- Now build and insert the call Insert_Action (N, Make_Raise_Constraint_Error (Loc, Condition => Make_Function_Call (Loc, Name => New_Occurrence_Of (Discr_Fct, Loc), Parameter_Associations => Args), Reason => CE_Discriminant_Check_Failed)); end Generate_Discriminant_Check; --------------------------- -- Generate_Index_Checks -- --------------------------- procedure Generate_Index_Checks (N : Node_Id) is function Entity_Of_Prefix return Entity_Id; -- Returns the entity of the prefix of N (or Empty if not found) ---------------------- -- Entity_Of_Prefix -- ---------------------- function Entity_Of_Prefix return Entity_Id is P : Node_Id; begin P := Prefix (N); while not Is_Entity_Name (P) loop if not Nkind_In (P, N_Selected_Component, N_Indexed_Component) then return Empty; end if; P := Prefix (P); end loop; return Entity (P); end Entity_Of_Prefix; -- Local variables Loc : constant Source_Ptr := Sloc (N); A : constant Node_Id := Prefix (N); A_Ent : constant Entity_Id := Entity_Of_Prefix; Sub : Node_Id; -- Start of processing for Generate_Index_Checks begin -- Ignore call if the prefix is not an array since we have a serious -- error in the sources. Ignore it also if index checks are suppressed -- for array object or type. if not Is_Array_Type (Etype (A)) or else (Present (A_Ent) and then Index_Checks_Suppressed (A_Ent)) or else Index_Checks_Suppressed (Etype (A)) then return; end if; -- Generate a raise of constraint error with the appropriate reason and -- a condition of the form: -- Base_Type (Sub) not in Array'Range (Subscript) -- Note that the reason we generate the conversion to the base type here -- is that we definitely want the range check to take place, even if it -- looks like the subtype is OK. Optimization considerations that allow -- us to omit the check have already been taken into account in the -- setting of the Do_Range_Check flag earlier on. Sub := First (Expressions (N)); -- Handle string literals if Ekind (Etype (A)) = E_String_Literal_Subtype then if Do_Range_Check (Sub) then Set_Do_Range_Check (Sub, False); -- For string literals we obtain the bounds of the string from the -- associated subtype. Insert_Action (N, Make_Raise_Constraint_Error (Loc, Condition => Make_Not_In (Loc, Left_Opnd => Convert_To (Base_Type (Etype (Sub)), Duplicate_Subexpr_Move_Checks (Sub)), Right_Opnd => Make_Attribute_Reference (Loc, Prefix => New_Reference_To (Etype (A), Loc), Attribute_Name => Name_Range)), Reason => CE_Index_Check_Failed)); end if; -- General case else declare A_Idx : Node_Id := Empty; A_Range : Node_Id; Ind : Nat; Num : List_Id; Range_N : Node_Id; begin A_Idx := First_Index (Etype (A)); Ind := 1; while Present (Sub) loop if Do_Range_Check (Sub) then Set_Do_Range_Check (Sub, False); -- Force evaluation except for the case of a simple name of -- a non-volatile entity. if not Is_Entity_Name (Sub) or else Treat_As_Volatile (Entity (Sub)) then Force_Evaluation (Sub); end if; if Nkind (A_Idx) = N_Range then A_Range := A_Idx; elsif Nkind (A_Idx) = N_Identifier or else Nkind (A_Idx) = N_Expanded_Name then A_Range := Scalar_Range (Entity (A_Idx)); else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication); A_Range := Range_Expression (Constraint (A_Idx)); end if; -- For array objects with constant bounds we can generate -- the index check using the bounds of the type of the index if Present (A_Ent) and then Ekind (A_Ent) = E_Variable and then Is_Constant_Bound (Low_Bound (A_Range)) and then Is_Constant_Bound (High_Bound (A_Range)) then Range_N := Make_Attribute_Reference (Loc, Prefix => New_Reference_To (Etype (A_Idx), Loc), Attribute_Name => Name_Range); -- For arrays with non-constant bounds we cannot generate -- the index check using the bounds of the type of the index -- since it may reference discriminants of some enclosing -- type. We obtain the bounds directly from the prefix -- object. else if Ind = 1 then Num := No_List; else Num := New_List (Make_Integer_Literal (Loc, Ind)); end if; Range_N := Make_Attribute_Reference (Loc, Prefix => Duplicate_Subexpr_Move_Checks (A, Name_Req => True), Attribute_Name => Name_Range, Expressions => Num); end if; Insert_Action (N, Make_Raise_Constraint_Error (Loc, Condition => Make_Not_In (Loc, Left_Opnd => Convert_To (Base_Type (Etype (Sub)), Duplicate_Subexpr_Move_Checks (Sub)), Right_Opnd => Range_N), Reason => CE_Index_Check_Failed)); end if; A_Idx := Next_Index (A_Idx); Ind := Ind + 1; Next (Sub); end loop; end; end if; end Generate_Index_Checks; -------------------------- -- Generate_Range_Check -- -------------------------- procedure Generate_Range_Check (N : Node_Id; Target_Type : Entity_Id; Reason : RT_Exception_Code) is Loc : constant Source_Ptr := Sloc (N); Source_Type : constant Entity_Id := Etype (N); Source_Base_Type : constant Entity_Id := Base_Type (Source_Type); Target_Base_Type : constant Entity_Id := Base_Type (Target_Type); begin -- First special case, if the source type is already within the range -- of the target type, then no check is needed (probably we should have -- stopped Do_Range_Check from being set in the first place, but better -- late than later in preventing junk code! -- We do NOT apply this if the source node is a literal, since in this -- case the literal has already been labeled as having the subtype of -- the target. if In_Subrange_Of (Source_Type, Target_Type) and then not (Nkind (N) = N_Integer_Literal or else Nkind (N) = N_Real_Literal or else Nkind (N) = N_Character_Literal or else (Is_Entity_Name (N) and then Ekind (Entity (N)) = E_Enumeration_Literal)) then return; end if; -- We need a check, so force evaluation of the node, so that it does -- not get evaluated twice (once for the check, once for the actual -- reference). Such a double evaluation is always a potential source -- of inefficiency, and is functionally incorrect in the volatile case. if not Is_Entity_Name (N) or else Treat_As_Volatile (Entity (N)) then Force_Evaluation (N); end if; -- The easiest case is when Source_Base_Type and Target_Base_Type are -- the same since in this case we can simply do a direct check of the -- value of N against the bounds of Target_Type. -- [constraint_error when N not in Target_Type] -- Note: this is by far the most common case, for example all cases of -- checks on the RHS of assignments are in this category, but not all -- cases are like this. Notably conversions can involve two types. if Source_Base_Type = Target_Base_Type then Insert_Action (N, Make_Raise_Constraint_Error (Loc, Condition => Make_Not_In (Loc, Left_Opnd => Duplicate_Subexpr (N), Right_Opnd => New_Occurrence_Of (Target_Type, Loc)), Reason => Reason)); -- Next test for the case where the target type is within the bounds -- of the base type of the source type, since in this case we can -- simply convert these bounds to the base type of T to do the test. -- [constraint_error when N not in -- Source_Base_Type (Target_Type'First) -- .. -- Source_Base_Type(Target_Type'Last))] -- The conversions will always work and need no check -- Unchecked_Convert_To is used instead of Convert_To to handle the case -- of converting from an enumeration value to an integer type, such as -- occurs for the case of generating a range check on Enum'Val(Exp) -- (which used to be handled by gigi). This is OK, since the conversion -- itself does not require a check. elsif In_Subrange_Of (Target_Type, Source_Base_Type) then Insert_Action (N, Make_Raise_Constraint_Error (Loc, Condition => Make_Not_In (Loc, Left_Opnd => Duplicate_Subexpr (N), Right_Opnd => Make_Range (Loc, Low_Bound => Unchecked_Convert_To (Source_Base_Type, Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (Target_Type, Loc), Attribute_Name => Name_First)), High_Bound => Unchecked_Convert_To (Source_Base_Type, Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (Target_Type, Loc), Attribute_Name => Name_Last)))), Reason => Reason)); -- Note that at this stage we now that the Target_Base_Type is not in -- the range of the Source_Base_Type (since even the Target_Type itself -- is not in this range). It could still be the case that Source_Type is -- in range of the target base type since we have not checked that case. -- If that is the case, we can freely convert the source to the target, -- and then test the target result against the bounds. elsif In_Subrange_Of (Source_Type, Target_Base_Type) then -- We make a temporary to hold the value of the converted value -- (converted to the base type), and then we will do the test against -- this temporary. -- Tnn : constant Target_Base_Type := Target_Base_Type (N); -- [constraint_error when Tnn not in Target_Type] -- Then the conversion itself is replaced by an occurrence of Tnn declare Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N); begin Insert_Actions (N, New_List ( Make_Object_Declaration (Loc, Defining_Identifier => Tnn, Object_Definition => New_Occurrence_Of (Target_Base_Type, Loc), Constant_Present => True, Expression => Make_Type_Conversion (Loc, Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc), Expression => Duplicate_Subexpr (N))), Make_Raise_Constraint_Error (Loc, Condition => Make_Not_In (Loc, Left_Opnd => New_Occurrence_Of (Tnn, Loc), Right_Opnd => New_Occurrence_Of (Target_Type, Loc)), Reason => Reason))); Rewrite (N, New_Occurrence_Of (Tnn, Loc)); -- Set the type of N, because the declaration for Tnn might not -- be analyzed yet, as is the case if N appears within a record -- declaration, as a discriminant constraint or expression. Set_Etype (N, Target_Base_Type); end; -- At this stage, we know that we have two scalar types, which are -- directly convertible, and where neither scalar type has a base -- range that is in the range of the other scalar type. -- The only way this can happen is with a signed and unsigned type. -- So test for these two cases: else -- Case of the source is unsigned and the target is signed if Is_Unsigned_Type (Source_Base_Type) and then not Is_Unsigned_Type (Target_Base_Type) then -- If the source is unsigned and the target is signed, then we -- know that the source is not shorter than the target (otherwise -- the source base type would be in the target base type range). -- In other words, the unsigned type is either the same size as -- the target, or it is larger. It cannot be smaller. pragma Assert (Esize (Source_Base_Type) >= Esize (Target_Base_Type)); -- We only need to check the low bound if the low bound of the -- target type is non-negative. If the low bound of the target -- type is negative, then we know that we will fit fine. -- If the high bound of the target type is negative, then we -- know we have a constraint error, since we can't possibly -- have a negative source. -- With these two checks out of the way, we can do the check -- using the source type safely -- This is definitely the most annoying case! -- [constraint_error -- when (Target_Type'First >= 0 -- and then -- N < Source_Base_Type (Target_Type'First)) -- or else Target_Type'Last < 0 -- or else N > Source_Base_Type (Target_Type'Last)]; -- We turn off all checks since we know that the conversions -- will work fine, given the guards for negative values. Insert_Action (N, Make_Raise_Constraint_Error (Loc, Condition => Make_Or_Else (Loc, Make_Or_Else (Loc, Left_Opnd => Make_And_Then (Loc, Left_Opnd => Make_Op_Ge (Loc, Left_Opnd => Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (Target_Type, Loc), Attribute_Name => Name_First), Right_Opnd => Make_Integer_Literal (Loc, Uint_0)), Right_Opnd => Make_Op_Lt (Loc, Left_Opnd => Duplicate_Subexpr (N), Right_Opnd => Convert_To (Source_Base_Type, Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (Target_Type, Loc), Attribute_Name => Name_First)))), Right_Opnd => Make_Op_Lt (Loc, Left_Opnd => Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (Target_Type, Loc), Attribute_Name => Name_Last), Right_Opnd => Make_Integer_Literal (Loc, Uint_0))), Right_Opnd => Make_Op_Gt (Loc, Left_Opnd => Duplicate_Subexpr (N), Right_Opnd => Convert_To (Source_Base_Type, Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (Target_Type, Loc), Attribute_Name => Name_Last)))), Reason => Reason), Suppress => All_Checks); -- Only remaining possibility is that the source is signed and -- the target is unsigned. else pragma Assert (not Is_Unsigned_Type (Source_Base_Type) and then Is_Unsigned_Type (Target_Base_Type)); -- If the source is signed and the target is unsigned, then we -- know that the target is not shorter than the source (otherwise -- the target base type would be in the source base type range). -- In other words, the unsigned type is either the same size as -- the target, or it is larger. It cannot be smaller. -- Clearly we have an error if the source value is negative since -- no unsigned type can have negative values. If the source type -- is non-negative, then the check can be done using the target -- type. -- Tnn : constant Target_Base_Type (N) := Target_Type; -- [constraint_error -- when N < 0 or else Tnn not in Target_Type]; -- We turn off all checks for the conversion of N to the target -- base type, since we generate the explicit check to ensure that -- the value is non-negative declare Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N); begin Insert_Actions (N, New_List ( Make_Object_Declaration (Loc, Defining_Identifier => Tnn, Object_Definition => New_Occurrence_Of (Target_Base_Type, Loc), Constant_Present => True, Expression => Make_Unchecked_Type_Conversion (Loc, Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc), Expression => Duplicate_Subexpr (N))), Make_Raise_Constraint_Error (Loc, Condition => Make_Or_Else (Loc, Left_Opnd => Make_Op_Lt (Loc, Left_Opnd => Duplicate_Subexpr (N), Right_Opnd => Make_Integer_Literal (Loc, Uint_0)), Right_Opnd => Make_Not_In (Loc, Left_Opnd => New_Occurrence_Of (Tnn, Loc), Right_Opnd => New_Occurrence_Of (Target_Type, Loc))), Reason => Reason)), Suppress => All_Checks); -- Set the Etype explicitly, because Insert_Actions may have -- placed the declaration in the freeze list for an enclosing -- construct, and thus it is not analyzed yet. Set_Etype (Tnn, Target_Base_Type); Rewrite (N, New_Occurrence_Of (Tnn, Loc)); end; end if; end if; end Generate_Range_Check; ------------------ -- Get_Check_Id -- ------------------ function Get_Check_Id (N : Name_Id) return Check_Id is begin -- For standard check name, we can do a direct computation if N in First_Check_Name .. Last_Check_Name then return Check_Id (N - (First_Check_Name - 1)); -- For non-standard names added by pragma Check_Name, search table else for J in All_Checks + 1 .. Check_Names.Last loop if Check_Names.Table (J) = N then return J; end if; end loop; end if; -- No matching name found return No_Check_Id; end Get_Check_Id; --------------------- -- 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 bound can be a bona fide parameter of a protected operation, -- rather than a prival encoded as an in-parameter. if No (Discriminal_Link (Entity (Bound))) then return Bound; end if; -- Climb the scope stack looking for an enclosing protected type. If -- we run out of scopes, return the bound itself. Sc := Scope (E); while Present (Sc) loop if Sc = Standard_Standard then return Bound; elsif Ekind (Sc) = E_Protected_Type then exit; end if; Sc := Scope (Sc); end loop; D := First_Discriminant (Sc); while Present (D) loop if Chars (D) = Chars (Bound) then return New_Occurrence_Of (Discriminal (D), Loc); end if; Next_Discriminant (D); end loop; return Bound; end Get_Discriminal; ---------------------- -- Get_Range_Checks -- ---------------------- function Get_Range_Checks (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 Get_Range_Checks; ------------------ -- 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_No_Checks (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 if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Index_Check); else return Scope_Suppress (Index_Check); end if; 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; Check_Names.Init; for J in Int range 1 .. All_Checks loop Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1)); 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 Full_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, Reason => CE_Range_Check_Failed); 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); Exp : Node_Id; begin -- Do not insert if checks off, or if not checking validity or -- if expression is known to be valid if not Validity_Checks_On or else Range_Or_Validity_Checks_Suppressed (Expr) or else Expr_Known_Valid (Expr) then return; end if; -- If we have a checked conversion, then validity check applies to -- the expression inside the conversion, not the result, since if -- the expression inside is valid, then so is the conversion result. Exp := Expr; while Nkind (Exp) = N_Type_Conversion loop Exp := Expression (Exp); end loop; -- We are about to insert the validity check for Exp. We save and -- reset the Do_Range_Check flag over this validity check, and then -- put it back for the final original reference (Exp may be rewritten). declare DRC : constant Boolean := Do_Range_Check (Exp); begin Set_Do_Range_Check (Exp, False); -- Force evaluation to avoid multiple reads for atomic/volatile if Is_Entity_Name (Exp) and then Is_Volatile (Entity (Exp)) then Force_Evaluation (Exp, Name_Req => True); end if; -- 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! Insert_Action (Expr, Make_Raise_Constraint_Error (Loc, Condition => Make_Op_Not (Loc, Right_Opnd => Make_Attribute_Reference (Loc, Prefix => Duplicate_Subexpr_No_Checks (Exp, Name_Req => True), Attribute_Name => Name_Valid)), Reason => CE_Invalid_Data), Suppress => Validity_Check); -- If the expression is a reference to an element of a bit-packed -- array, then it is rewritten as a renaming declaration. If the -- expression is an actual in a call, it has not been expanded, -- waiting for the proper point at which to do it. The same happens -- with renamings, so that we have to force the expansion now. This -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb -- and exp_ch6.adb. if Is_Entity_Name (Exp) and then Nkind (Parent (Entity (Exp))) = N_Object_Renaming_Declaration then declare Old_Exp : constant Node_Id := Name (Parent (Entity (Exp))); begin if Nkind (Old_Exp) = N_Indexed_Component and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp))) then Expand_Packed_Element_Reference (Old_Exp); end if; end; end if; -- Put back the Do_Range_Check flag on the resulting (possibly -- rewritten) expression. -- Note: it might be thought that a validity check is not required -- when a range check is present, but that's not the case, because -- the back end is allowed to assume for the range check that the -- operand is within its declared range (an assumption that validity -- checking is all about NOT assuming!) -- Note: no need to worry about Possible_Local_Raise here, it will -- already have been called if original node has Do_Range_Check set. Set_Do_Range_Check (Exp, DRC); end; end Insert_Valid_Check; ---------------------------------- -- Install_Null_Excluding_Check -- ---------------------------------- procedure Install_Null_Excluding_Check (N : Node_Id) is Loc : constant Source_Ptr := Sloc (Parent (N)); Typ : constant Entity_Id := Etype (N); function Safe_To_Capture_In_Parameter_Value return Boolean; -- Determines if it is safe to capture Known_Non_Null status for an -- the entity referenced by node N. The caller ensures that N is indeed -- an entity name. It is safe to capture the non-null status for an IN -- parameter when the reference occurs within a declaration that is sure -- to be executed as part of the declarative region. procedure Mark_Non_Null; -- After installation of check, if the node in question is an entity -- name, then mark this entity as non-null if possible. function Safe_To_Capture_In_Parameter_Value return Boolean is E : constant Entity_Id := Entity (N); S : constant Entity_Id := Current_Scope; S_Par : Node_Id; begin if Ekind (E) /= E_In_Parameter then return False; end if; -- Two initial context checks. We must be inside a subprogram body -- with declarations and reference must not appear in nested scopes. if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure) or else Scope (E) /= S then return False; end if; S_Par := Parent (Parent (S)); if Nkind (S_Par) /= N_Subprogram_Body or else No (Declarations (S_Par)) then return False; end if; declare N_Decl : Node_Id; P : Node_Id; begin -- Retrieve the declaration node of N (if any). Note that N -- may be a part of a complex initialization expression. P := Parent (N); N_Decl := Empty; while Present (P) loop -- If we have a short circuit form, and we are within the right -- hand expression, we return false, since the right hand side -- is not guaranteed to be elaborated. if Nkind (P) in N_Short_Circuit and then N = Right_Opnd (P) then return False; end if; -- Similarly, if we are in a conditional expression and not -- part of the condition, then we return False, since neither -- the THEN or ELSE expressions will always be elaborated. if Nkind (P) = N_Conditional_Expression and then N /= First (Expressions (P)) then return False; end if; -- If we are in a case expression, and not part of the -- expression, then we return False, since a particular -- branch may not always be elaborated if Nkind (P) = N_Case_Expression and then N /= Expression (P) then return False; end if; -- While traversing the parent chain, we find that N -- belongs to a statement, thus it may never appear in -- a declarative region. if Nkind (P) in N_Statement_Other_Than_Procedure_Call or else Nkind (P) = N_Procedure_Call_Statement then return False; end if; -- If we are at a declaration, record it and exit if Nkind (P) in N_Declaration and then Nkind (P) not in N_Subprogram_Specification then N_Decl := P; exit; end if; P := Parent (P); end loop; if No (N_Decl) then return False; end if; return List_Containing (N_Decl) = Declarations (S_Par); end; end Safe_To_Capture_In_Parameter_Value; ------------------- -- Mark_Non_Null -- ------------------- procedure Mark_Non_Null is begin -- Only case of interest is if node N is an entity name if Is_Entity_Name (N) then -- For sure, we want to clear an indication that this is known to -- be null, since if we get past this check, it definitely is not! Set_Is_Known_Null (Entity (N), False); -- We can mark the entity as known to be non-null if either it is -- safe to capture the value, or in the case of an IN parameter, -- which is a constant, if the check we just installed is in the -- declarative region of the subprogram body. In this latter case, -- a check is decisive for the rest of the body if the expression -- is sure to be elaborated, since we know we have to elaborate -- all declarations before executing the body. -- Couldn't this always be part of Safe_To_Capture_Value ??? if Safe_To_Capture_Value (N, Entity (N)) or else Safe_To_Capture_In_Parameter_Value then Set_Is_Known_Non_Null (Entity (N)); end if; end if; end Mark_Non_Null; -- Start of processing for Install_Null_Excluding_Check begin pragma Assert (Is_Access_Type (Typ)); -- No check inside a generic (why not???) if Inside_A_Generic then return; end if; -- No check needed if known to be non-null if Known_Non_Null (N) then return; end if; -- If known to be null, here is where we generate a compile time check if Known_Null (N) then -- Avoid generating warning message inside init procs if not Inside_Init_Proc then Apply_Compile_Time_Constraint_Error (N, "null value not allowed here?", CE_Access_Check_Failed); else Insert_Action (N, Make_Raise_Constraint_Error (Loc, Reason => CE_Access_Check_Failed)); end if; Mark_Non_Null; return; end if; -- If entity is never assigned, for sure a warning is appropriate if Is_Entity_Name (N) then Check_Unset_Reference (N); end if; -- No check needed if checks are suppressed on the range. Note that we -- don't set Is_Known_Non_Null in this case (we could legitimately do -- so, since the program is erroneous, but we don't like to casually -- propagate such conclusions from erroneosity). if Access_Checks_Suppressed (Typ) then return; end if; -- No check needed for access to concurrent record types generated by -- the expander. This is not just an optimization (though it does indeed -- remove junk checks). It also avoids generation of junk warnings. if Nkind (N) in N_Has_Chars and then Chars (N) = Name_uObject and then Is_Concurrent_Record_Type (Directly_Designated_Type (Etype (N))) then return; end if; -- No check needed for the Get_Current_Excep.all.all idiom generated by -- the expander within exception handlers, since we know that the value -- can never be null. -- Is this really the right way to do this? Normally we generate such -- code in the expander with checks off, and that's how we suppress this -- kind of junk check ??? if Nkind (N) = N_Function_Call and then Nkind (Name (N)) = N_Explicit_Dereference and then Nkind (Prefix (Name (N))) = N_Identifier and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep) then return; end if; -- Otherwise install access check Insert_Action (N, Make_Raise_Constraint_Error (Loc, Condition => Make_Op_Eq (Loc, Left_Opnd => Duplicate_Subexpr_Move_Checks (N), Right_Opnd => Make_Null (Loc)), Reason => CE_Access_Check_Failed)); Mark_Non_Null; end Install_Null_Excluding_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, Reason => CE_Range_Check_Failed)); Set_Analyzed (R_Cno); Set_Etype (R_Cno, Typ); Set_Raises_Constraint_Error (R_Cno); Set_Is_Static_Expression (R_Cno, Stat); -- Now deal with possible local raise handling Possible_Local_Raise (R_Cno, Standard_Constraint_Error); end Install_Static_Check; --------------------- -- Kill_All_Checks -- --------------------- procedure Kill_All_Checks is begin if Debug_Flag_CC then w ("Kill_All_Checks"); end if; -- We reset the number of saved checks to zero, and also modify all -- stack entries for statement ranges to indicate that the number of -- checks at each level is now zero. Num_Saved_Checks := 0; -- Note: the Int'Min here avoids any possibility of J being out of -- range when called from e.g. Conditional_Statements_Begin. for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop Saved_Checks_Stack (J) := 0; end loop; end Kill_All_Checks; ----------------- -- Kill_Checks -- ----------------- procedure Kill_Checks (V : Entity_Id) is begin if Debug_Flag_CC then w ("Kill_Checks for entity", Int (V)); end if; for J in 1 .. Num_Saved_Checks loop if Saved_Checks (J).Entity = V then if Debug_Flag_CC then w (" Checks killed for saved check ", J); end if; Saved_Checks (J).Killed := True; end if; end loop; end Kill_Checks; ------------------------------ -- Length_Checks_Suppressed -- ------------------------------ function Length_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Length_Check); else return Scope_Suppress (Length_Check); end if; end Length_Checks_Suppressed; -------------------------------- -- Overflow_Checks_Suppressed -- -------------------------------- function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Overflow_Check); else return Scope_Suppress (Overflow_Check); end if; end Overflow_Checks_Suppressed; ----------------------------- -- Range_Checks_Suppressed -- ----------------------------- function Range_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) then -- Note: for now we always suppress range checks on Vax float types, -- since Gigi does not know how to generate these checks. if Vax_Float (E) then return True; elsif Kill_Range_Checks (E) then return True; elsif Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Range_Check); end if; end if; return Scope_Suppress (Range_Check); end Range_Checks_Suppressed; ----------------------------------------- -- Range_Or_Validity_Checks_Suppressed -- ----------------------------------------- -- Note: the coding would be simpler here if we simply made appropriate -- calls to Range/Validity_Checks_Suppressed, but that would result in -- duplicated checks which we prefer to avoid. function Range_Or_Validity_Checks_Suppressed (Expr : Node_Id) return Boolean is begin -- Immediate return if scope checks suppressed for either check if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then return True; end if; -- If no expression, that's odd, decide that checks are suppressed, -- since we don't want anyone trying to do checks in this case, which -- is most likely the result of some other error. if No (Expr) then return True; end if; -- Expression is present, so perform suppress checks on type declare Typ : constant Entity_Id := Etype (Expr); begin if Vax_Float (Typ) then return True; elsif Checks_May_Be_Suppressed (Typ) and then (Is_Check_Suppressed (Typ, Range_Check) or else Is_Check_Suppressed (Typ, Validity_Check)) then return True; end if; end; -- If expression is an entity name, perform checks on this entity if Is_Entity_Name (Expr) then declare Ent : constant Entity_Id := Entity (Expr); begin if Checks_May_Be_Suppressed (Ent) then return Is_Check_Suppressed (Ent, Range_Check) or else Is_Check_Suppressed (Ent, Validity_Check); end if; end; end if; -- If we fall through, no checks suppressed return False; end Range_Or_Validity_Checks_Suppressed; ------------------- -- Remove_Checks -- ------------------- procedure Remove_Checks (Expr : Node_Id) is function Process (N : Node_Id) return Traverse_Result; -- Process a single node during the traversal procedure Traverse is new Traverse_Proc (Process); -- The traversal procedure itself ------------- -- Process -- ------------- function Process (N : Node_Id) return Traverse_Result is begin if Nkind (N) not in N_Subexpr then return Skip; end if; Set_Do_Range_Check (N, False); case Nkind (N) is when N_And_Then => Traverse (Left_Opnd (N)); return Skip; when N_Attribute_Reference => Set_Do_Overflow_Check (N, False); when N_Function_Call => Set_Do_Tag_Check (N, False); when N_Op => Set_Do_Overflow_Check (N, False); case Nkind (N) is when N_Op_Divide => Set_Do_Division_Check (N, False); when N_Op_And => Set_Do_Length_Check (N, False); when N_Op_Mod => Set_Do_Division_Check (N, False); when N_Op_Or => Set_Do_Length_Check (N, False); when N_Op_Rem => Set_Do_Division_Check (N, False); when N_Op_Xor => Set_Do_Length_Check (N, False); when others => null; end case; when N_Or_Else => Traverse (Left_Opnd (N)); return Skip; when N_Selected_Component => Set_Do_Discriminant_Check (N, False); when N_Type_Conversion => Set_Do_Length_Check (N, False); Set_Do_Tag_Check (N, False); Set_Do_Overflow_Check (N, False); when others => null; end case; return OK; end Process; -- Start of processing for Remove_Checks begin Traverse (Expr); end Remove_Checks; ---------------------------- -- 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; -- Comments required ??? 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 includes the -- case of a discriminal reference within an init proc. 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 SE : constant Entity_Id := Scope (E); N : Node_Id; E1 : Entity_Id := 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 SE /= Standard_Standard and then Ekind (Scope (SE)) = E_Protected_Type and then Has_Discriminants (Scope (SE)) and then Has_Completion (Scope (SE)) 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_No_Checks (Lo); end if; if not Is_Entity_Name (Hi) then Lo := Duplicate_Subexpr_No_Checks (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_No_Checks (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; ----------------- -- Same_Bounds -- ----------------- 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))) or else (Is_Entity_Name (L) and then Is_Entity_Name (R) and then Entity (L) = Entity (R) and then Ekind (Entity (L)) = E_In_Parameter and then Inside_Init_Proc); end Same_Bounds; -- Start of processing for Selected_Length_Checks begin if not Full_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 for the null case if Known_Null (Ck_Node) 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 conditional expression, but ahead of it. Freeze_Before (Ck_Node, T_Typ); Expr_Actual := Get_Referenced_Object (Ck_Node); Exptyp := Get_Actual_Subtype (Ck_Node); 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 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype 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 Ndims : constant Nat := Number_Dimensions (T_Typ); L_Index : Node_Id; R_Index : Node_Id; L_Low : Node_Id; L_High : Node_Id; R_Low : Node_Id; R_High : Node_Id; L_Length : Uint; R_Length : Uint; Ref_Node : Node_Id; begin -- At the library level, we need to ensure that the type of -- the object is elaborated before the check itself is -- emitted. This is only done if the object is in the -- current compilation unit, otherwise the type is frozen -- and elaborated in its unit. if Is_Itype (Exptyp) and then Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package and then not In_Package_Body (Cunit_Entity (Current_Sem_Unit)) and then In_Open_Scopes (Scope (Exptyp)) then Ref_Node := Make_Itype_Reference (Sloc (Ck_Node)); Set_Itype (Ref_Node, Exptyp); Insert_Action (Ck_Node, Ref_Node); end if; 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 : constant 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, Reason => CE_Length_Check_Failed)); 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 (Loc : Source_Ptr; E : Entity_Id; Indx : Nat; Nam : Name_Id) return Node_Id; -- Returns an attribute reference -- E'First or E'Last -- with a source location of Loc. -- -- Nam is Name_First or Name_Last, according to which attribute is -- desired. If Indx is non-zero, it is passed as a literal in the -- Expressions of the attribute reference (identifying the desired -- array dimension). 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_No_Checks 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_No_Checks (Expr)), Right_Opnd => Convert_To (Base_Type (Typ), Get_E_First_Or_Last (Loc, Typ, 0, Name_First))), Right_Opnd => Make_Op_Gt (Loc, Left_Opnd => Convert_To (Base_Type (Typ), Duplicate_Subexpr_No_Checks (Expr)), Right_Opnd => Convert_To (Base_Type (Typ), Get_E_First_Or_Last (Loc, 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_No_Checks (LB)), Right_Opnd => Convert_To (Base_Type (Typ), Get_E_First_Or_Last (Loc, 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_No_Checks (HB)), Right_Opnd => Convert_To (Base_Type (Typ), Get_E_First_Or_Last (Loc, 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 (Loc : Source_Ptr; E : Entity_Id; Indx : Nat; Nam : Name_Id) return Node_Id is Exprs : List_Id; begin if Indx > 0 then Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx))); else Exprs := No_List; end if; return Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (E, Loc), Attribute_Name => Nam, Expressions => Exprs); 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_No_Checks (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_No_Checks (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 (Loc, Exptyp, Indx, Name_First), Right_Opnd => Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)), Right_Opnd => Make_Op_Gt (Loc, Left_Opnd => Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last), Right_Opnd => Get_E_First_Or_Last (Loc, 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 (Loc, Exptyp, Indx, Name_First), Right_Opnd => Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)), Right_Opnd => Make_Op_Ne (Loc, Left_Opnd => Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last), Right_Opnd => Get_E_First_Or_Last (Loc, 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 (Loc, Typ, Indx, Name_First)), Right_Opnd => Make_Op_Gt (Loc, Left_Opnd => Get_N_Last (Expr, Indx), Right_Opnd => Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last))); end Range_N_Cond; -- Start of processing for Selected_Range_Checks begin if not Full_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 for the null case if Known_Null (Ck_Node) 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); Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB); Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB); LB : Node_Id := Low_Bound (Ck_Node); HB : Node_Id := High_Bound (Ck_Node); Known_LB : Boolean; Known_HB : Boolean; Null_Range : Boolean; Out_Of_Range_L : Boolean; Out_Of_Range_H : Boolean; begin -- Compute what is known at compile time if Known_T_LB and Known_T_HB then if Compile_Time_Known_Value (LB) then Known_LB := True; -- There's no point in checking that a bound is within its -- own range so pretend that it is known in this case. First -- deal with low bound. elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ) then LB := T_LB; Known_LB := True; else Known_LB := False; end if; -- Likewise for the high bound if Compile_Time_Known_Value (HB) then Known_HB := True; elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ) then HB := T_HB; Known_HB := True; else Known_HB := False; end if; end if; -- 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 Known_T_LB and Known_T_HB and Known_LB and Known_HB and 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. -- Similarly, if the entity is a discriminal, there is no -- check to perform yet. -- The same holds within a discriminated synchronized type, -- where the discriminant may constrain a component or an -- entry family. if Nkind (LB) = N_Identifier and then Denotes_Discriminant (LB, True) then if Current_Scope = Scope (Entity (LB)) or else Is_Concurrent_Type (Current_Scope) or else Ekind (Entity (LB)) /= E_Discriminant then return Ret_Result; else LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc); end if; end if; if Nkind (HB) = N_Identifier and then Denotes_Discriminant (HB, True) then if Current_Scope = Scope (Entity (HB)) or else Is_Concurrent_Type (Current_Scope) or else Ekind (Entity (HB)) /= E_Discriminant 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_No_Checks (HB), Right_Opnd => Duplicate_Subexpr_No_Checks (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)); -- Fixed or discrete type else 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 output 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 Ndims : constant Nat := Number_Dimensions (T_Typ); L_Index : Node_Id; R_Index : 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 -- 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 : constant 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 -- For a conversion to an unconstrained array type, generate an -- Action to check that the bounds of the source value are within -- the constraints imposed by the target type (RM 4.6(38)). No -- check is needed for a conversion to an access to unconstrained -- array type, as 4.6(24.15/2) requires the designated subtypes -- of the two access types to statically match. if Nkind (Parent (Ck_Node)) = N_Type_Conversion and then not Do_Access then declare Opnd_Index : Node_Id; Targ_Index : Node_Id; Opnd_Range : Node_Id; begin Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node)); Targ_Index := First_Index (T_Typ); while Present (Opnd_Index) loop -- If the index is a range, use its bounds. If it is an -- entity (as will be the case if it is a named subtype -- or an itype created for a slice) retrieve its range. if Is_Entity_Name (Opnd_Index) and then Is_Type (Entity (Opnd_Index)) then Opnd_Range := Scalar_Range (Entity (Opnd_Index)); else Opnd_Range := Opnd_Index; end if; if Nkind (Opnd_Range) = N_Range then if Is_In_Range (Low_Bound (Opnd_Range), Etype (Targ_Index), Assume_Valid => True) and then Is_In_Range (High_Bound (Opnd_Range), Etype (Targ_Index), Assume_Valid => True) then null; -- If null range, no check needed elsif Compile_Time_Known_Value (High_Bound (Opnd_Range)) and then Compile_Time_Known_Value (Low_Bound (Opnd_Range)) and then Expr_Value (High_Bound (Opnd_Range)) < Expr_Value (Low_Bound (Opnd_Range)) then null; elsif Is_Out_Of_Range (Low_Bound (Opnd_Range), Etype (Targ_Index), Assume_Valid => True) or else Is_Out_Of_Range (High_Bound (Opnd_Range), Etype (Targ_Index), Assume_Valid => True) then Add_Check (Compile_Time_Constraint_Error (Wnode, "value out of range of}?", T_Typ)); else Evolve_Or_Else (Cond, Discrete_Range_Cond (Opnd_Range, 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, Reason => CE_Range_Check_Failed)); end if; return Ret_Result; end Selected_Range_Checks; ------------------------------- -- Storage_Checks_Suppressed -- ------------------------------- function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Storage_Check); else return Scope_Suppress (Storage_Check); end if; end Storage_Checks_Suppressed; --------------------------- -- Tag_Checks_Suppressed -- --------------------------- function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) then if Kill_Tag_Checks (E) then return True; elsif Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Tag_Check); end if; end if; return Scope_Suppress (Tag_Check); end Tag_Checks_Suppressed; -------------------------- -- Validity_Check_Range -- -------------------------- procedure Validity_Check_Range (N : Node_Id) is begin if Validity_Checks_On and Validity_Check_Operands then if Nkind (N) = N_Range then Ensure_Valid (Low_Bound (N)); Ensure_Valid (High_Bound (N)); end if; end if; end Validity_Check_Range; -------------------------------- -- Validity_Checks_Suppressed -- -------------------------------- function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is begin if Present (E) and then Checks_May_Be_Suppressed (E) then return Is_Check_Suppressed (E, Validity_Check); else return Scope_Suppress (Validity_Check); end if; end Validity_Checks_Suppressed; end Checks;
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