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Diffstat (limited to 'gcc-4.9/gcc/ada/checks.adb')
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diff --git a/gcc-4.9/gcc/ada/checks.adb b/gcc-4.9/gcc/ada/checks.adb new file mode 100644 index 000000000..7d3979dcb --- /dev/null +++ b/gcc-4.9/gcc/ada/checks.adb @@ -0,0 +1,9501 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- C H E C K S -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2013, 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 Casing; use Casing; +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 Expander; use Expander; +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 Stringt; use Stringt; +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. + + -- The above is modified in gnatprove mode to ensure that proper check + -- flags are always placed, even if expansion is off. + + ------------------------------------- + -- 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_Arithmetic_Overflow_Strict (N : Node_Id); + -- Used to apply arithmetic overflow checks for all cases except operators + -- on signed arithmetic types in MINIMIZED/ELIMINATED case (for which we + -- call Apply_Arithmetic_Overflow_Minimized_Eliminated below). N can be a + -- signed integer arithmetic operator (but not an if or case expression). + -- It is also called for types other than signed integers. + + procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id); + -- Used to apply arithmetic overflow checks for the case where the overflow + -- checking mode is MINIMIZED or ELIMINATED and we have a signed integer + -- arithmetic op (which includes the case of if and case expressions). Note + -- that Do_Overflow_Check may or may not be set for node Op. In these modes + -- we have work to do even if overflow checking is suppressed. + + procedure Apply_Division_Check + (N : Node_Id; + Rlo : Uint; + Rhi : Uint; + ROK : Boolean); + -- N is an N_Op_Div, N_Op_Rem, or N_Op_Mod node. This routine applies + -- division checks as required if the Do_Division_Check flag is set. + -- Rlo and Rhi give the possible range of the right operand, these values + -- can be referenced and trusted only if ROK is set True. + + 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 Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean; + -- Returns True if node N is for an arithmetic operation with signed + -- integer operands. This includes unary and binary operators, and also + -- if and case expression nodes where the dependent expressions are of + -- a signed integer type. These are the kinds of nodes for which special + -- handling applies in MINIMIZED or ELIMINATED overflow checking mode. + + 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.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.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 + if not Nkind_In (N, N_Op_Rem, N_Op_Mod, N_Op_Plus) then + Set_Do_Overflow_Check (N, True); + Possible_Local_Raise (N, Standard_Constraint_Error); + end if; + 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.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 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 + pragma Assert (Nkind (N) = N_Freeze_Entity); + + 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 + ("?o?specified address for& may be inconsistent with alignment", + Aexp, E); + Error_Msg_FE + ("\?o?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; + + if No (Actions (N)) then + Set_Actions (N, New_List); + end if; + + Prepend_To (Actions (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)); + Analyze (First (Actions (N)), Suppress => All_Checks); + + -- If the address clause generates an alignment check and we are + -- in ZPF or some restricted run-time, add a warning to explain + -- the propagation warning that is generated by the check. + + if Nkind (First (Actions (N))) = N_Raise_Program_Error + and then not Warnings_Off (E) + and then Restriction_Active (No_Exception_Propagation) + then + Error_Msg_N + ("address value may be incompatible with alignment of object?", + N); + end if; + + 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 -- + ------------------------------------- + + procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is + begin + -- Use old routine in almost all cases (the only case we are treating + -- specially is the case of a signed integer arithmetic op with the + -- overflow checking mode set to MINIMIZED or ELIMINATED). + + if Overflow_Check_Mode = Strict + or else not Is_Signed_Integer_Arithmetic_Op (N) + then + Apply_Arithmetic_Overflow_Strict (N); + + -- Otherwise use the new routine for the case of a signed integer + -- arithmetic op, with Do_Overflow_Check set to True, and the checking + -- mode is MINIMIZED or ELIMINATED. + + else + Apply_Arithmetic_Overflow_Minimized_Eliminated (N); + end if; + end Apply_Arithmetic_Overflow_Check; + + -------------------------------------- + -- Apply_Arithmetic_Overflow_Strict -- + -------------------------------------- + + -- 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. + + -- This is used in CHECKED modes. It is identical to the code for this + -- cases before the big overflow earthquake, thus ensuring that in this + -- modes we have compatible behavior (and reliability) to what was there + -- before. It is also called for types other than signed integers, and if + -- the Do_Overflow_Check flag is off. + + -- Note: we also call this routine if we decide in the MINIMIZED case + -- to give up and just generate an overflow check without any fuss. + + procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id) is + Loc : constant Source_Ptr := Sloc (N); + Typ : constant Entity_Id := Etype (N); + Rtyp : constant Entity_Id := Root_Type (Typ); + + begin + -- Nothing to do if Do_Overflow_Check not set or overflow checks + -- suppressed. + + if not Do_Overflow_Check (N) then + return; + end if; + + -- 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 + Conversion_Optimization : 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 Conversion_Optimization; + 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 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_Occurrence_Of (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_Strict; + + ---------------------------------------------------- + -- Apply_Arithmetic_Overflow_Minimized_Eliminated -- + ---------------------------------------------------- + + procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id) is + pragma Assert (Is_Signed_Integer_Arithmetic_Op (Op)); + + Loc : constant Source_Ptr := Sloc (Op); + P : constant Node_Id := Parent (Op); + + LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer); + -- Operands and results are of this type when we convert + + Result_Type : constant Entity_Id := Etype (Op); + -- Original result type + + Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode; + pragma Assert (Check_Mode in Minimized_Or_Eliminated); + + Lo, Hi : Uint; + -- Ranges of values for result + + begin + -- Nothing to do if our parent is one of the following: + + -- Another signed integer arithmetic op + -- A membership operation + -- A comparison operation + + -- In all these cases, we will process at the higher level (and then + -- this node will be processed during the downwards recursion that + -- is part of the processing in Minimize_Eliminate_Overflows). + + if Is_Signed_Integer_Arithmetic_Op (P) + or else Nkind (P) in N_Membership_Test + or else Nkind (P) in N_Op_Compare + + -- This is also true for an alternative in a case expression + + or else Nkind (P) = N_Case_Expression_Alternative + + -- This is also true for a range operand in a membership test + + or else (Nkind (P) = N_Range + and then Nkind (Parent (P)) in N_Membership_Test) + then + return; + end if; + + -- Otherwise, we have a top level arithmetic operation node, and this + -- is where we commence the special processing for MINIMIZED/ELIMINATED + -- modes. This is the case where we tell the machinery not to move into + -- Bignum mode at this top level (of course the top level operation + -- will still be in Bignum mode if either of its operands are of type + -- Bignum). + + Minimize_Eliminate_Overflows (Op, Lo, Hi, Top_Level => True); + + -- That call may but does not necessarily change the result type of Op. + -- It is the job of this routine to undo such changes, so that at the + -- top level, we have the proper type. This "undoing" is a point at + -- which a final overflow check may be applied. + + -- If the result type was not fiddled we are all set. We go to base + -- types here because things may have been rewritten to generate the + -- base type of the operand types. + + if Base_Type (Etype (Op)) = Base_Type (Result_Type) then + return; + + -- Bignum case + + elsif Is_RTE (Etype (Op), RE_Bignum) then + + -- We need a sequence that looks like: + + -- Rnn : Result_Type; + + -- declare + -- M : Mark_Id := SS_Mark; + -- begin + -- Rnn := Long_Long_Integer'Base (From_Bignum (Op)); + -- SS_Release (M); + -- end; + + -- This block is inserted (using Insert_Actions), and then the node + -- is replaced with a reference to Rnn. + + -- A special case arises if our parent is a conversion node. In this + -- case no point in generating a conversion to Result_Type, we will + -- let the parent handle this. Note that this special case is not + -- just about optimization. Consider + + -- A,B,C : Integer; + -- ... + -- X := Long_Long_Integer'Base (A * (B ** C)); + + -- Now the product may fit in Long_Long_Integer but not in Integer. + -- In MINIMIZED/ELIMINATED mode, we don't want to introduce an + -- overflow exception for this intermediate value. + + declare + Blk : constant Node_Id := Make_Bignum_Block (Loc); + Rnn : constant Entity_Id := Make_Temporary (Loc, 'R', Op); + RHS : Node_Id; + + Rtype : Entity_Id; + + begin + RHS := Convert_From_Bignum (Op); + + if Nkind (P) /= N_Type_Conversion then + Convert_To_And_Rewrite (Result_Type, RHS); + Rtype := Result_Type; + + -- Interesting question, do we need a check on that conversion + -- operation. Answer, not if we know the result is in range. + -- At the moment we are not taking advantage of this. To be + -- looked at later ??? + + else + Rtype := LLIB; + end if; + + Insert_Before + (First (Statements (Handled_Statement_Sequence (Blk))), + Make_Assignment_Statement (Loc, + Name => New_Occurrence_Of (Rnn, Loc), + Expression => RHS)); + + Insert_Actions (Op, New_List ( + Make_Object_Declaration (Loc, + Defining_Identifier => Rnn, + Object_Definition => New_Occurrence_Of (Rtype, Loc)), + Blk)); + + Rewrite (Op, New_Occurrence_Of (Rnn, Loc)); + Analyze_And_Resolve (Op); + end; + + -- Here we know the result is Long_Long_Integer'Base, of that it has + -- been rewritten because the parent operation is a conversion. See + -- Apply_Arithmetic_Overflow_Strict.Conversion_Optimization. + + else + pragma Assert + (Etype (Op) = LLIB or else Nkind (Parent (Op)) = N_Type_Conversion); + + -- All we need to do here is to convert the result to the proper + -- result type. As explained above for the Bignum case, we can + -- omit this if our parent is a type conversion. + + if Nkind (P) /= N_Type_Conversion then + Convert_To_And_Rewrite (Result_Type, Op); + end if; + + Analyze_And_Resolve (Op); + end if; + end Apply_Arithmetic_Overflow_Minimized_Eliminated; + + ---------------------------- + -- 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 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 Object_Type_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 rewritten as + -- an 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; + + -- Constraint may appear in full view of type + + if Ekind (T_Typ) = E_Private_Subtype + and then Present (Full_View (T_Typ)) + then + DconT := + First_Elmt (Discriminant_Constraint (Full_View (T_Typ))); + else + DconT := + First_Elmt (Discriminant_Constraint (T_Typ)); + end if; + + 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_Checks -- + ------------------------- + + procedure Apply_Divide_Checks (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); + + Mode : constant Overflow_Mode_Type := Overflow_Check_Mode; + -- Current overflow checking mode + + 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 we are operating in MINIMIZED or ELIMINATED mode, and we are + -- operating on signed integer types, then the only thing this routine + -- does is to call Apply_Arithmetic_Overflow_Minimized_Eliminated. That + -- procedure will (possibly later on during recursive downward calls), + -- ensure that any needed overflow/division checks are properly applied. + + if Mode in Minimized_Or_Eliminated + and then Is_Signed_Integer_Type (Typ) + then + Apply_Arithmetic_Overflow_Minimized_Eliminated (N); + return; + end if; + + -- Proceed here in SUPPRESSED or CHECKED modes + + if 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); + + -- Deal with division check + + if Do_Division_Check (N) + and then not Division_Checks_Suppressed (Typ) + then + Apply_Division_Check (N, Rlo, Rhi, ROK); + end if; + + -- Deal with overflow check + + if Do_Overflow_Check (N) + and then not Overflow_Checks_Suppressed (Etype (N)) + then + -- Test for extremely annoying case of xxx'First divided by -1 + -- for division of signed integer types (only overflow case). + + 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, + Left_Opnd => + Make_Op_Eq (Loc, + Left_Opnd => + Duplicate_Subexpr_Move_Checks (Left), + Right_Opnd => Make_Integer_Literal (Loc, LLB)), + + Right_Opnd => + 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_Checks; + + -------------------------- + -- Apply_Division_Check -- + -------------------------- + + procedure Apply_Division_Check + (N : Node_Id; + Rlo : Uint; + Rhi : Uint; + ROK : Boolean) + is + pragma Assert (Do_Division_Check (N)); + + Loc : constant Source_Ptr := Sloc (N); + Right : constant Node_Id := Right_Opnd (N); + + begin + if Expander_Active + and then not Backend_Divide_Checks_On_Target + and then Check_Needed (Right, Division_Check) + then + -- See if division by zero possible, and if so generate test. This + -- part of the test is not controlled by the -gnato switch, since + -- it is a Division_Check and not an Overflow_Check. + + 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; + end if; + end Apply_Division_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 + -- We do not need checks if we are not generating code (i.e. the full + -- expander is not active). In SPARK mode, we specifically don't want + -- the frontend to expand these checks, which are dealt with directly + -- in the formal verification backend. + + if not Expander_Active then + return; + end if; + + 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_Parameter_Aliasing_Checks -- + ------------------------------------- + + procedure Apply_Parameter_Aliasing_Checks + (Call : Node_Id; + Subp : Entity_Id) + is + Loc : constant Source_Ptr := Sloc (Call); + + function May_Cause_Aliasing + (Formal_1 : Entity_Id; + Formal_2 : Entity_Id) return Boolean; + -- Determine whether two formal parameters can alias each other + -- depending on their modes. + + function Original_Actual (N : Node_Id) return Node_Id; + -- The expander may replace an actual with a temporary for the sake of + -- side effect removal. The temporary may hide a potential aliasing as + -- it does not share the address of the actual. This routine attempts + -- to retrieve the original actual. + + procedure Overlap_Check + (Actual_1 : Node_Id; + Actual_2 : Node_Id; + Formal_1 : Entity_Id; + Formal_2 : Entity_Id; + Check : in out Node_Id); + -- Create a check to determine whether Actual_1 overlaps with Actual_2. + -- If detailed exception messages are enabled, the check is augmented to + -- provide information about the names of the corresponding formals. See + -- the body for details. Actual_1 and Actual_2 denote the two actuals to + -- be tested. Formal_1 and Formal_2 denote the corresponding formals. + -- Check contains all and-ed simple tests generated so far or remains + -- unchanged in the case of detailed exception messaged. + + ------------------------ + -- May_Cause_Aliasing -- + ------------------------ + + function May_Cause_Aliasing + (Formal_1 : Entity_Id; + Formal_2 : Entity_Id) return Boolean + is + begin + -- The following combination cannot lead to aliasing + + -- Formal 1 Formal 2 + -- IN IN + + if Ekind (Formal_1) = E_In_Parameter + and then + Ekind (Formal_2) = E_In_Parameter + then + return False; + + -- The following combinations may lead to aliasing + + -- Formal 1 Formal 2 + -- IN OUT + -- IN IN OUT + -- OUT IN + -- OUT IN OUT + -- OUT OUT + + else + return True; + end if; + end May_Cause_Aliasing; + + --------------------- + -- Original_Actual -- + --------------------- + + function Original_Actual (N : Node_Id) return Node_Id is + begin + if Nkind (N) = N_Type_Conversion then + return Expression (N); + + -- The expander created a temporary to capture the result of a type + -- conversion where the expression is the real actual. + + elsif Nkind (N) = N_Identifier + and then Present (Original_Node (N)) + and then Nkind (Original_Node (N)) = N_Type_Conversion + then + return Expression (Original_Node (N)); + end if; + + return N; + end Original_Actual; + + ------------------- + -- Overlap_Check -- + ------------------- + + procedure Overlap_Check + (Actual_1 : Node_Id; + Actual_2 : Node_Id; + Formal_1 : Entity_Id; + Formal_2 : Entity_Id; + Check : in out Node_Id) + is + Cond : Node_Id; + ID_Casing : constant Casing_Type := + Identifier_Casing (Source_Index (Current_Sem_Unit)); + + begin + -- Generate: + -- Actual_1'Overlaps_Storage (Actual_2) + + Cond := + Make_Attribute_Reference (Loc, + Prefix => New_Copy_Tree (Original_Actual (Actual_1)), + Attribute_Name => Name_Overlaps_Storage, + Expressions => + New_List (New_Copy_Tree (Original_Actual (Actual_2)))); + + -- Generate the following check when detailed exception messages are + -- enabled: + + -- if Actual_1'Overlaps_Storage (Actual_2) then + -- raise Program_Error with <detailed message>; + -- end if; + + if Exception_Extra_Info then + Start_String; + + -- Do not generate location information for internal calls + + if Comes_From_Source (Call) then + Store_String_Chars (Build_Location_String (Loc)); + Store_String_Char (' '); + end if; + + Store_String_Chars ("aliased parameters, actuals for """); + + Get_Name_String (Chars (Formal_1)); + Set_Casing (ID_Casing); + Store_String_Chars (Name_Buffer (1 .. Name_Len)); + + Store_String_Chars (""" and """); + + Get_Name_String (Chars (Formal_2)); + Set_Casing (ID_Casing); + Store_String_Chars (Name_Buffer (1 .. Name_Len)); + + Store_String_Chars (""" overlap"); + + Insert_Action (Call, + Make_If_Statement (Loc, + Condition => Cond, + Then_Statements => New_List ( + Make_Raise_Statement (Loc, + Name => + New_Occurrence_Of (Standard_Program_Error, Loc), + Expression => Make_String_Literal (Loc, End_String))))); + + -- Create a sequence of overlapping checks by and-ing them all + -- together. + + else + if No (Check) then + Check := Cond; + else + Check := + Make_And_Then (Loc, + Left_Opnd => Check, + Right_Opnd => Cond); + end if; + end if; + end Overlap_Check; + + -- Local variables + + Actual_1 : Node_Id; + Actual_2 : Node_Id; + Check : Node_Id; + Formal_1 : Entity_Id; + Formal_2 : Entity_Id; + + -- Start of processing for Apply_Parameter_Aliasing_Checks + + begin + Check := Empty; + + Actual_1 := First_Actual (Call); + Formal_1 := First_Formal (Subp); + while Present (Actual_1) and then Present (Formal_1) loop + + -- Ensure that the actual is an object that is not passed by value. + -- Elementary types are always passed by value, therefore actuals of + -- such types cannot lead to aliasing. + + if Is_Object_Reference (Original_Actual (Actual_1)) + and then not Is_Elementary_Type (Etype (Original_Actual (Actual_1))) + then + Actual_2 := Next_Actual (Actual_1); + Formal_2 := Next_Formal (Formal_1); + while Present (Actual_2) and then Present (Formal_2) loop + + -- The other actual we are testing against must also denote + -- a non pass-by-value object. Generate the check only when + -- the mode of the two formals may lead to aliasing. + + if Is_Object_Reference (Original_Actual (Actual_2)) + and then not + Is_Elementary_Type (Etype (Original_Actual (Actual_2))) + and then May_Cause_Aliasing (Formal_1, Formal_2) + then + Overlap_Check + (Actual_1 => Actual_1, + Actual_2 => Actual_2, + Formal_1 => Formal_1, + Formal_2 => Formal_2, + Check => Check); + end if; + + Next_Actual (Actual_2); + Next_Formal (Formal_2); + end loop; + end if; + + Next_Actual (Actual_1); + Next_Formal (Formal_1); + end loop; + + -- Place a simple check right before the call + + if Present (Check) and then not Exception_Extra_Info then + Insert_Action (Call, + Make_Raise_Program_Error (Loc, + Condition => Check, + Reason => PE_Aliased_Parameters)); + end if; + end Apply_Parameter_Aliasing_Checks; + + ------------------------------------- + -- Apply_Parameter_Validity_Checks -- + ------------------------------------- + + procedure Apply_Parameter_Validity_Checks (Subp : Entity_Id) is + Subp_Decl : Node_Id; + + procedure Add_Validity_Check + (Context : Entity_Id; + PPC_Nam : Name_Id; + For_Result : Boolean := False); + -- Add a single 'Valid[_Scalar] check which verifies the initialization + -- of Context. PPC_Nam denotes the pre or post condition pragma name. + -- Set flag For_Result when to verify the result of a function. + + procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id); + -- Create a pre or post condition pragma with name PPC_Nam which + -- tests expression Check. + + ------------------------ + -- Add_Validity_Check -- + ------------------------ + + procedure Add_Validity_Check + (Context : Entity_Id; + PPC_Nam : Name_Id; + For_Result : Boolean := False) + is + Loc : constant Source_Ptr := Sloc (Subp); + Typ : constant Entity_Id := Etype (Context); + Check : Node_Id; + Nam : Name_Id; + + begin + -- Pick the proper version of 'Valid depending on the type of the + -- context. If the context is not eligible for such a check, return. + + if Is_Scalar_Type (Typ) then + Nam := Name_Valid; + elsif not No_Scalar_Parts (Typ) then + Nam := Name_Valid_Scalars; + else + return; + end if; + + -- Step 1: Create the expression to verify the validity of the + -- context. + + Check := New_Occurrence_Of (Context, Loc); + + -- When processing a function result, use 'Result. Generate + -- Context'Result + + if For_Result then + Check := + Make_Attribute_Reference (Loc, + Prefix => Check, + Attribute_Name => Name_Result); + end if; + + -- Generate: + -- Context['Result]'Valid[_Scalars] + + Check := + Make_Attribute_Reference (Loc, + Prefix => Check, + Attribute_Name => Nam); + + -- Step 2: Create a pre or post condition pragma + + Build_PPC_Pragma (PPC_Nam, Check); + end Add_Validity_Check; + + ---------------------- + -- Build_PPC_Pragma -- + ---------------------- + + procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id) is + Loc : constant Source_Ptr := Sloc (Subp); + Decls : List_Id; + Prag : Node_Id; + + begin + Prag := + Make_Pragma (Loc, + Pragma_Identifier => Make_Identifier (Loc, PPC_Nam), + Pragma_Argument_Associations => New_List ( + Make_Pragma_Argument_Association (Loc, + Chars => Name_Check, + Expression => Check))); + + -- Add a message unless exception messages are suppressed + + if not Exception_Locations_Suppressed then + Append_To (Pragma_Argument_Associations (Prag), + Make_Pragma_Argument_Association (Loc, + Chars => Name_Message, + Expression => + Make_String_Literal (Loc, + Strval => "failed " & Get_Name_String (PPC_Nam) & + " from " & Build_Location_String (Loc)))); + end if; + + -- Insert the pragma in the tree + + if Nkind (Parent (Subp_Decl)) = N_Compilation_Unit then + Add_Global_Declaration (Prag); + Analyze (Prag); + + -- PPC pragmas associated with subprogram bodies must be inserted in + -- the declarative part of the body. + + elsif Nkind (Subp_Decl) = N_Subprogram_Body then + Decls := Declarations (Subp_Decl); + + if No (Decls) then + Decls := New_List; + Set_Declarations (Subp_Decl, Decls); + end if; + + Prepend_To (Decls, Prag); + + -- Ensure the proper visibility of the subprogram body and its + -- parameters. + + Push_Scope (Subp); + Analyze (Prag); + Pop_Scope; + + -- For subprogram declarations insert the PPC pragma right after the + -- declarative node. + + else + Insert_After_And_Analyze (Subp_Decl, Prag); + end if; + end Build_PPC_Pragma; + + -- Local variables + + Formal : Entity_Id; + Subp_Spec : Node_Id; + + -- Start of processing for Apply_Parameter_Validity_Checks + + begin + -- Extract the subprogram specification and declaration nodes + + Subp_Spec := Parent (Subp); + + if Nkind (Subp_Spec) = N_Defining_Program_Unit_Name then + Subp_Spec := Parent (Subp_Spec); + end if; + + Subp_Decl := Parent (Subp_Spec); + + if not Comes_From_Source (Subp) + + -- Do not process formal subprograms because the corresponding actual + -- will receive the proper checks when the instance is analyzed. + + or else Is_Formal_Subprogram (Subp) + + -- Do not process imported subprograms since pre and post conditions + -- are never verified on routines coming from a different language. + + or else Is_Imported (Subp) + or else Is_Intrinsic_Subprogram (Subp) + + -- The PPC pragmas generated by this routine do not correspond to + -- source aspects, therefore they cannot be applied to abstract + -- subprograms. + + or else Nkind (Subp_Decl) = N_Abstract_Subprogram_Declaration + + -- Do not consider subprogram renaminds because the renamed entity + -- already has the proper PPC pragmas. + + or else Nkind (Subp_Decl) = N_Subprogram_Renaming_Declaration + + -- Do not process null procedures because there is no benefit of + -- adding the checks to a no action routine. + + or else (Nkind (Subp_Spec) = N_Procedure_Specification + and then Null_Present (Subp_Spec)) + then + return; + end if; + + -- Inspect all the formals applying aliasing and scalar initialization + -- checks where applicable. + + Formal := First_Formal (Subp); + while Present (Formal) loop + + -- Generate the following scalar initialization checks for each + -- formal parameter: + + -- mode IN - Pre => Formal'Valid[_Scalars] + -- mode IN OUT - Pre, Post => Formal'Valid[_Scalars] + -- mode OUT - Post => Formal'Valid[_Scalars] + + if Check_Validity_Of_Parameters then + if Ekind_In (Formal, E_In_Parameter, E_In_Out_Parameter) then + Add_Validity_Check (Formal, Name_Precondition, False); + end if; + + if Ekind_In (Formal, E_In_Out_Parameter, E_Out_Parameter) then + Add_Validity_Check (Formal, Name_Postcondition, False); + end if; + end if; + + Next_Formal (Formal); + end loop; + + -- Generate following scalar initialization check for function result: + + -- Post => Subp'Result'Valid[_Scalars] + + if Check_Validity_Of_Parameters and then Ekind (Subp) = E_Function then + Add_Validity_Check (Subp, Name_Postcondition, True); + end if; + end Apply_Parameter_Validity_Checks; + + --------------------------- + -- Apply_Predicate_Check -- + --------------------------- + + procedure Apply_Predicate_Check (N : Node_Id; Typ : Entity_Id) is + S : Entity_Id; + + begin + if Present (Predicate_Function (Typ)) then + + S := Current_Scope; + while Present (S) and then not Is_Subprogram (S) loop + S := Scope (S); + end loop; + + -- A predicate check does not apply within internally generated + -- subprograms, such as TSS functions. + + if Within_Internal_Subprogram then + return; + + -- If the check appears within the predicate function itself, it + -- means that the user specified a check whose formal is the + -- predicated subtype itself, rather than some covering type. This + -- is likely to be a common error, and thus deserves a warning. + + elsif Present (S) and then S = Predicate_Function (Typ) then + Error_Msg_N + ("predicate check includes a function call that " + & "requires a predicate check??", Parent (N)); + Error_Msg_N + ("\this will result in infinite recursion??", Parent (N)); + Insert_Action (N, + Make_Raise_Storage_Error (Sloc (N), + Reason => SE_Infinite_Recursion)); + + -- Here for normal case of predicate active + + else + -- If the type has a static predicate and the expression is known + -- at compile time, see if the expression satisfies the predicate. + + Check_Expression_Against_Static_Predicate (N, Typ); + + Insert_Action (N, + Make_Predicate_Check (Typ, Duplicate_Subexpr (N))); + end if; + 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); + + -- Special checks for floating-point type + + if Is_Floating_Point_Type (S_Typ) then + + -- 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 Has_Infinities (S_Typ) + and then not Has_Infinities (Target_Typ) + then + Enable_Range_Check (Expr); + + -- Always do a range check for operators if option set + + elsif Check_Float_Overflow and then Nkind (Expr) in N_Op then + Enable_Range_Check (Expr); + end if; + 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; + + -- Floating-point case + -- 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 + + -- Normally, we only do range checks if the type is constrained. We do + -- NOT want range checks for unconstrained types, since we want to have + -- infinities. Override this decision in Check_Float_Overflow mode. + + if Is_Constrained (S_Typ) or else Check_Float_Overflow 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 + -- Note: this means that we lose some useful warnings if the expander + -- is not active, and we also lose these warnings in SPARK mode ??? + + if not 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 + 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); + + Cond : Node_Id; + R_Cno : Node_Id; + R_Result : Check_Result; + + begin + if not Expander_Active or 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); + + -- The range check requires runtime evaluation. Depending on what its + -- triggering condition is, the check may be converted into a compile + -- time constraint check. + + if Nkind (R_Cno) = N_Raise_Constraint_Error + and then Present (Condition (R_Cno)) + then + Cond := Condition (R_Cno); + + -- Insert the range check before the related context. Note that + -- this action analyses the triggering condition. + + Insert_Action (Ck_Node, R_Cno); + + -- This old code doesn't make sense, why is the context flagged as + -- requiring dynamic range checks now in the middle of generating + -- them ??? + + if not Do_Static then + Set_Has_Dynamic_Range_Check (Ck_Node); + end if; + + -- The triggering condition evaluates to True, the range check + -- can be converted into a compile time constraint check. + + 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 + + -- Why are we even generating checks if checks are turned off ??? + + elsif Do_Static or else not Checks_On then + Remove_Warning_Messages (R_Cno); + Rewrite (R_Cno, Make_Null_Statement (Loc)); + end if; + + -- The range check raises Constrant_Error explicitly + + 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; + + -- Never generate discriminant checks for Unchecked_Union types + + elsif Present (Expr_Type) + and then Is_Unchecked_Union (Expr_Type) + 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 Overflow_Checks_Suppressed (Target_Type) + 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, checks are set now, but 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. Note that the range check is put on the expression of a + -- type conversion, while the length check is put on the type conversion + -- itself. + + elsif Is_Array_Type (Target_Type) then + if Is_Constrained (Target_Type) then + Set_Do_Length_Check (N); + else + Set_Do_Range_Check (Expr); + end if; + 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.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; + + function Left_Expression (Op : Node_Id) return Node_Id; + -- Return the relevant expression from the left operand of the given + -- short circuit form: this is LO itself, except if LO is a qualified + -- expression, a type conversion, or an expression with actions, in + -- which case this is Left_Expression (Expression (LO)). + + --------------------- + -- Left_Expression -- + --------------------- + + function Left_Expression (Op : Node_Id) return Node_Id is + LE : Node_Id := Left_Opnd (Op); + begin + while Nkind_In (LE, N_Qualified_Expression, + N_Type_Conversion, + N_Expression_With_Actions) + loop + LE := Expression (LE); + end loop; + + return LE; + end Left_Expression; + + -- Start of processing for Check_Needed + + 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_Expression (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_Expression (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_Expression (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_Expression (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 look further. + + L := Left_Expression (P); + + -- L is an "=" or "/=" operator: extract its operands + + 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 + Error_Msg_Warn := SPARK_Mode /= On; + + case Check is + when Access_Check => + if GNATprove_Mode then + Error_Msg_N + ("Constraint_Error might have been raised (access check)", + Parent (Nod)); + else + Error_Msg_N + ("Constraint_Error may be raised (access check)??", + Parent (Nod)); + end if; + + when Division_Check => + if GNATprove_Mode then + Error_Msg_N + ("Constraint_Error might have been raised (zero divide)", + Parent (Nod)); + else + Error_Msg_N + ("Constraint_Error may be raised (zero divide)??", + Parent (Nod)); + end if; + + 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 + (Nkind_In (K, N_Component_Declaration, + N_Discriminant_Specification, + N_Function_Specification, + N_Object_Declaration, + 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; + + ------------------------- + -- Convert_From_Bignum -- + ------------------------- + + function Convert_From_Bignum (N : Node_Id) return Node_Id is + Loc : constant Source_Ptr := Sloc (N); + + begin + pragma Assert (Is_RTE (Etype (N), RE_Bignum)); + + -- Construct call From Bignum + + return + Make_Function_Call (Loc, + Name => + New_Occurrence_Of (RTE (RE_From_Bignum), Loc), + Parameter_Associations => New_List (Relocate_Node (N))); + end Convert_From_Bignum; + + ----------------------- + -- Convert_To_Bignum -- + ----------------------- + + function Convert_To_Bignum (N : Node_Id) return Node_Id is + Loc : constant Source_Ptr := Sloc (N); + + begin + -- Nothing to do if Bignum already except call Relocate_Node + + if Is_RTE (Etype (N), RE_Bignum) then + return Relocate_Node (N); + + -- Otherwise construct call to To_Bignum, converting the operand to the + -- required Long_Long_Integer form. + + else + pragma Assert (Is_Signed_Integer_Type (Etype (N))); + return + Make_Function_Call (Loc, + Name => + New_Occurrence_Of (RTE (RE_To_Bignum), Loc), + Parameter_Associations => New_List ( + Convert_To (Standard_Long_Long_Integer, Relocate_Node (N)))); + end if; + end Convert_To_Bignum; + + --------------------- + -- 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 + + Btyp : Entity_Id; + -- Base type + + 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; + + -- Retrieve the base type. Handle the case where the base type is a + -- private enumeration type. + + Btyp := Base_Type (Typ); + + if Is_Private_Type (Btyp) and then Present (Full_View (Btyp)) then + Btyp := Full_View (Btyp); + 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 (Btyp)) then + Lo := Expr_Value (Type_Low_Bound (Btyp)); + + 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 (Btyp)) then + Hbound := Expr_Value (Type_High_Bound (Btyp)); + 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 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.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.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.Suppress (Elaboration_Check) then + return True; + elsif Dynamic_Elaboration_Checks then + return Scope_Suppress.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)); + Mode : constant Overflow_Mode_Type := Overflow_Check_Mode; + 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 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; + end if; + + -- This is the point at which processing for STRICT mode diverges + -- from processing for MINIMIZED/ELIMINATED modes. This divergence is + -- probably more extreme that it needs to be, but what is going on here + -- is that when we introduced MINIMIZED/ELIMINATED modes, we wanted + -- to leave the processing for STRICT mode untouched. There were + -- two reasons for this. First it avoided any incompatible change of + -- behavior. Second, it guaranteed that STRICT mode continued to be + -- legacy reliable. + + -- The big difference is that in STRICT mode there is a fair amount of + -- circuitry to try to avoid setting the Do_Overflow_Check flag if we + -- know that no check is needed. We skip all that in the two new modes, + -- since really overflow checking happens over a whole subtree, and we + -- do the corresponding optimizations later on when applying the checks. + + if Mode in Minimized_Or_Eliminated then + if not (Overflow_Checks_Suppressed (Etype (N))) + and then not (Is_Entity_Name (N) + and then Overflow_Checks_Suppressed (Entity (N))) + then + Activate_Overflow_Check (N); + end if; + + if Debug_Flag_CC then + w ("Minimized/Eliminated mode"); + end if; + + return; + end if; + + -- Remainder of processing is for STRICT case, and is unchanged from + -- earlier versions preceding the addition of MINIMIZED/ELIMINATED. + + -- 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. + + if 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; + + -- For an expression with actions, we want to insert the validity check + -- on the final Expression. + + elsif Nkind (Expr) = N_Expression_With_Actions then + Ensure_Valid (Expression (Expr)); + 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)) + + -- Exclude volatile variables + + and then not Treat_As_Volatile (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_In (Expr, N_Integer_Literal, N_Character_Literal) then + return True; + + -- Real literals are assumed to be valid in VM targets + + elsif VM_Target /= No_VM and then Nkind (Expr) = N_Real_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_In (Expr, N_Type_Conversion, N_Qualified_Expression) then + return Expr_Known_Valid (Expression (Expr)); + + -- Case of expression is a non-floating-point operator. In this case we + -- can assume the result is valid the generated code for the operator + -- will include whatever checks are needed (e.g. range checks) to ensure + -- validity. This assumption does not hold for the floating-point case, + -- since floating-point operators can generate Infinite or NaN results + -- which are considered invalid. + + -- Historical note: in older versions, the exemption of floating-point + -- types from this assumption was done only in cases where the parent + -- was an assignment, function call or parameter association. Presumably + -- the idea was that in other contexts, the result would be checked + -- elsewhere, but this list of cases was missing tests (at least the + -- N_Object_Declaration case, as shown by a reported missing validity + -- check), and it is not clear why function calls but not procedure + -- calls were tested for. It really seems more accurate and much + -- safer to recognize that expressions which are the result of a + -- floating-point operator can never be assumed to be valid. + + elsif Nkind (Expr) in N_Op and then not Is_Floating_Point_Type (Typ) then + return True; + + -- 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. A non-volatile entity or a component of a + -- non-volatile 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; + + -- The indexed component we are dealing with contains 'Loop_Entry in its + -- prefix. This case arises when analysis has determined that constructs + -- such as + + -- Prefix'Loop_Entry (Expr) + -- Prefix'Loop_Entry (Expr1, Expr2, ... ExprN) + + -- require rewriting for error detection purposes. A side effect of this + -- action is the generation of index checks that mention 'Loop_Entry. + -- Delay the generation of the check until 'Loop_Entry has been properly + -- expanded. This is done in Expand_Loop_Entry_Attributes. + + elsif Nkind (Prefix (N)) = N_Attribute_Reference + and then Attribute_Name (Prefix (N)) = Name_Loop_Entry + 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_Occurrence_Of (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_Occurrence_Of (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 never in preventing junk code. + + if In_Subrange_Of (Source_Type, Target_Type) + + -- 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. + + and then not + (Nkind_In (N, N_Integer_Literal, N_Real_Literal, N_Character_Literal) + or else + (Is_Entity_Name (N) + and then Ekind (Entity (N)) = E_Enumeration_Literal)) + + -- Also do not apply this for floating-point if Check_Float_Overflow + + and then not + (Is_Floating_Point_Type (Source_Type) and Check_Float_Overflow) + 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.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 Expander_Active or 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); + Typ : constant Entity_Id := Etype (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; + + -- Do not insert checks within a predicate function. This will arise + -- if the current unit and the predicate function are being compiled + -- with validity checks enabled. + + if Present (Predicate_Function (Typ)) + and then Current_Scope = Predicate_Function (Typ) + 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); + PV : Node_Id; + CE : Node_Id; + + 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; + + -- Build the prefix for the 'Valid call + + PV := Duplicate_Subexpr_No_Checks (Exp, Name_Req => True); + + -- A rather specialized kludge. If PV is an analyzed expression + -- which is an indexed component of a packed array that has not + -- been properly expanded, turn off its Analyzed flag to make sure + -- it gets properly reexpanded. + + -- The reason this arises is that Duplicate_Subexpr_No_Checks did + -- an analyze with the old parent pointer. This may point e.g. to + -- a subprogram call, which deactivates this expansion. + + if Analyzed (PV) + and then Nkind (PV) = N_Indexed_Component + and then Present (Packed_Array_Type (Etype (Prefix (PV)))) + then + Set_Analyzed (PV, False); + end if; + + -- Build the raise CE node to check for validity + + CE := + Make_Raise_Constraint_Error (Loc, + Condition => + Make_Op_Not (Loc, + Right_Opnd => + Make_Attribute_Reference (Loc, + Prefix => PV, + Attribute_Name => Name_Valid)), + Reason => CE_Invalid_Data); + + -- 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, CE, 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; + + ------------------------------------- + -- Is_Signed_Integer_Arithmetic_Op -- + ------------------------------------- + + function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean is + begin + case Nkind (N) is + when N_Op_Abs | N_Op_Add | N_Op_Divide | N_Op_Expon | + N_Op_Minus | N_Op_Mod | N_Op_Multiply | N_Op_Plus | + N_Op_Rem | N_Op_Subtract => + return Is_Signed_Integer_Type (Etype (N)); + + when N_If_Expression | N_Case_Expression => + return Is_Signed_Integer_Type (Etype (N)); + + when others => + return False; + end case; + end Is_Signed_Integer_Arithmetic_Op; + + ---------------------------------- + -- 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 an if expression and not part of the + -- condition, then we return False, since neither the THEN or + -- ELSE dependent expressions will always be elaborated. + + if Nkind (P) = N_If_Expression + and then N /= First (Expressions (P)) + then + return False; + end if; + + -- If within a case expression, and not part of the expression, + -- then return False, since a particular dependent expression + -- 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, if node N belongs to a + -- statement, then 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, check will be emitted in instance + + 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. In SPARK mode + -- we can go ahead and call Apply_Compile_Time_Constraint_Error + -- since it will be turned into an error in any case. + + if (not Inside_Init_Proc or else SPARK_Mode = On) + + -- Do not emit the warning within a conditional expression, + -- where the expression might not be evaluated, and the warning + -- appear as extraneous noise. + + and then not Within_Case_Or_If_Expression (N) + then + Apply_Compile_Time_Constraint_Error + (N, "null value not allowed here??", CE_Access_Check_Failed); + + -- Remaining cases, where we silently insert the raise + + 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 in interface thunks since the runtime check is + -- already performed at the caller side. + + if Is_Thunk (Current_Scope) 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; + + ------------------------- + -- Is_Check_Suppressed -- + ------------------------- + + function Is_Check_Suppressed (E : Entity_Id; C : Check_Id) return Boolean is + Ptr : Suppress_Stack_Entry_Ptr; + + begin + -- First search the local entity suppress stack. We search this from the + -- top of the stack down so that we get the innermost entry that applies + -- to this case if there are nested entries. + + Ptr := Local_Suppress_Stack_Top; + while Ptr /= null loop + if (Ptr.Entity = Empty or else Ptr.Entity = E) + and then (Ptr.Check = All_Checks or else Ptr.Check = C) + then + return Ptr.Suppress; + end if; + + Ptr := Ptr.Prev; + end loop; + + -- Now search the global entity suppress table for a matching entry. + -- We also search this from the top down so that if there are multiple + -- pragmas for the same entity, the last one applies (not clear what + -- or whether the RM specifies this handling, but it seems reasonable). + + Ptr := Global_Suppress_Stack_Top; + while Ptr /= null loop + if (Ptr.Entity = Empty or else Ptr.Entity = E) + and then (Ptr.Check = All_Checks or else Ptr.Check = C) + then + return Ptr.Suppress; + end if; + + Ptr := Ptr.Prev; + end loop; + + -- If we did not find a matching entry, then use the normal scope + -- suppress value after all (actually this will be the global setting + -- since it clearly was not overridden at any point). For a predefined + -- check, we test the specific flag. For a user defined check, we check + -- the All_Checks flag. The Overflow flag requires special handling to + -- deal with the General vs Assertion case + + if C = Overflow_Check then + return Overflow_Checks_Suppressed (Empty); + elsif C in Predefined_Check_Id then + return Scope_Suppress.Suppress (C); + else + return Scope_Suppress.Suppress (All_Checks); + end if; + end Is_Check_Suppressed; + + --------------------- + -- 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.Suppress (Length_Check); + end if; + end Length_Checks_Suppressed; + + ----------------------- + -- Make_Bignum_Block -- + ----------------------- + + function Make_Bignum_Block (Loc : Source_Ptr) return Node_Id is + M : constant Entity_Id := Make_Defining_Identifier (Loc, Name_uM); + + begin + return + Make_Block_Statement (Loc, + Declarations => New_List ( + Make_Object_Declaration (Loc, + Defining_Identifier => M, + Object_Definition => + New_Occurrence_Of (RTE (RE_Mark_Id), Loc), + Expression => + Make_Function_Call (Loc, + Name => New_Occurrence_Of (RTE (RE_SS_Mark), Loc)))), + + Handled_Statement_Sequence => + Make_Handled_Sequence_Of_Statements (Loc, + Statements => New_List ( + Make_Procedure_Call_Statement (Loc, + Name => New_Occurrence_Of (RTE (RE_SS_Release), Loc), + Parameter_Associations => New_List ( + New_Occurrence_Of (M, Loc)))))); + end Make_Bignum_Block; + + ---------------------------------- + -- Minimize_Eliminate_Overflows -- + ---------------------------------- + + -- This is a recursive routine that is called at the top of an expression + -- tree to properly process overflow checking for a whole subtree by making + -- recursive calls to process operands. This processing may involve the use + -- of bignum or long long integer arithmetic, which will change the types + -- of operands and results. That's why we can't do this bottom up (since + -- it would interfere with semantic analysis). + + -- What happens is that if MINIMIZED/ELIMINATED mode is in effect then + -- the operator expansion routines, as well as the expansion routines for + -- if/case expression, do nothing (for the moment) except call the routine + -- to apply the overflow check (Apply_Arithmetic_Overflow_Check). That + -- routine does nothing for non top-level nodes, so at the point where the + -- call is made for the top level node, the entire expression subtree has + -- not been expanded, or processed for overflow. All that has to happen as + -- a result of the top level call to this routine. + + -- As noted above, the overflow processing works by making recursive calls + -- for the operands, and figuring out what to do, based on the processing + -- of these operands (e.g. if a bignum operand appears, the parent op has + -- to be done in bignum mode), and the determined ranges of the operands. + + -- After possible rewriting of a constituent subexpression node, a call is + -- made to either reexpand the node (if nothing has changed) or reanalyze + -- the node (if it has been modified by the overflow check processing). The + -- Analyzed_Flag is set to False before the reexpand/reanalyze. To avoid + -- a recursive call into the whole overflow apparatus, an important rule + -- for this call is that the overflow handling mode must be temporarily set + -- to STRICT. + + procedure Minimize_Eliminate_Overflows + (N : Node_Id; + Lo : out Uint; + Hi : out Uint; + Top_Level : Boolean) + is + Rtyp : constant Entity_Id := Etype (N); + pragma Assert (Is_Signed_Integer_Type (Rtyp)); + -- Result type, must be a signed integer type + + Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode; + pragma Assert (Check_Mode in Minimized_Or_Eliminated); + + Loc : constant Source_Ptr := Sloc (N); + + Rlo, Rhi : Uint; + -- Ranges of values for right operand (operator case) + + Llo, Lhi : Uint; + -- Ranges of values for left operand (operator case) + + LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer); + -- Operands and results are of this type when we convert + + LLLo : constant Uint := Intval (Type_Low_Bound (LLIB)); + LLHi : constant Uint := Intval (Type_High_Bound (LLIB)); + -- Bounds of Long_Long_Integer + + Binary : constant Boolean := Nkind (N) in N_Binary_Op; + -- Indicates binary operator case + + OK : Boolean; + -- Used in call to Determine_Range + + Bignum_Operands : Boolean; + -- Set True if one or more operands is already of type Bignum, meaning + -- that for sure (regardless of Top_Level setting) we are committed to + -- doing the operation in Bignum mode (or in the case of a case or if + -- expression, converting all the dependent expressions to Bignum). + + Long_Long_Integer_Operands : Boolean; + -- Set True if one or more operands is already of type Long_Long_Integer + -- which means that if the result is known to be in the result type + -- range, then we must convert such operands back to the result type. + + procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False); + -- This is called when we have modified the node and we therefore need + -- to reanalyze it. It is important that we reset the mode to STRICT for + -- this reanalysis, since if we leave it in MINIMIZED or ELIMINATED mode + -- we would reenter this routine recursively which would not be good. + -- The argument Suppress is set True if we also want to suppress + -- overflow checking for the reexpansion (this is set when we know + -- overflow is not possible). Typ is the type for the reanalysis. + + procedure Reexpand (Suppress : Boolean := False); + -- This is like Reanalyze, but does not do the Analyze step, it only + -- does a reexpansion. We do this reexpansion in STRICT mode, so that + -- instead of reentering the MINIMIZED/ELIMINATED mode processing, we + -- follow the normal expansion path (e.g. converting A**4 to A**2**2). + -- Note that skipping reanalysis is not just an optimization, testing + -- has showed up several complex cases in which reanalyzing an already + -- analyzed node causes incorrect behavior. + + function In_Result_Range return Boolean; + -- Returns True iff Lo .. Hi are within range of the result type + + procedure Max (A : in out Uint; B : Uint); + -- If A is No_Uint, sets A to B, else to UI_Max (A, B) + + procedure Min (A : in out Uint; B : Uint); + -- If A is No_Uint, sets A to B, else to UI_Min (A, B) + + --------------------- + -- In_Result_Range -- + --------------------- + + function In_Result_Range return Boolean is + begin + if Lo = No_Uint or else Hi = No_Uint then + return False; + + elsif Is_Static_Subtype (Etype (N)) then + return Lo >= Expr_Value (Type_Low_Bound (Rtyp)) + and then + Hi <= Expr_Value (Type_High_Bound (Rtyp)); + + else + return Lo >= Expr_Value (Type_Low_Bound (Base_Type (Rtyp))) + and then + Hi <= Expr_Value (Type_High_Bound (Base_Type (Rtyp))); + end if; + end In_Result_Range; + + --------- + -- Max -- + --------- + + procedure Max (A : in out Uint; B : Uint) is + begin + if A = No_Uint or else B > A then + A := B; + end if; + end Max; + + --------- + -- Min -- + --------- + + procedure Min (A : in out Uint; B : Uint) is + begin + if A = No_Uint or else B < A then + A := B; + end if; + end Min; + + --------------- + -- Reanalyze -- + --------------- + + procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False) is + Svg : constant Overflow_Mode_Type := + Scope_Suppress.Overflow_Mode_General; + Sva : constant Overflow_Mode_Type := + Scope_Suppress.Overflow_Mode_Assertions; + Svo : constant Boolean := + Scope_Suppress.Suppress (Overflow_Check); + + begin + Scope_Suppress.Overflow_Mode_General := Strict; + Scope_Suppress.Overflow_Mode_Assertions := Strict; + + if Suppress then + Scope_Suppress.Suppress (Overflow_Check) := True; + end if; + + Analyze_And_Resolve (N, Typ); + + Scope_Suppress.Suppress (Overflow_Check) := Svo; + Scope_Suppress.Overflow_Mode_General := Svg; + Scope_Suppress.Overflow_Mode_Assertions := Sva; + end Reanalyze; + + -------------- + -- Reexpand -- + -------------- + + procedure Reexpand (Suppress : Boolean := False) is + Svg : constant Overflow_Mode_Type := + Scope_Suppress.Overflow_Mode_General; + Sva : constant Overflow_Mode_Type := + Scope_Suppress.Overflow_Mode_Assertions; + Svo : constant Boolean := + Scope_Suppress.Suppress (Overflow_Check); + + begin + Scope_Suppress.Overflow_Mode_General := Strict; + Scope_Suppress.Overflow_Mode_Assertions := Strict; + Set_Analyzed (N, False); + + if Suppress then + Scope_Suppress.Suppress (Overflow_Check) := True; + end if; + + Expand (N); + + Scope_Suppress.Suppress (Overflow_Check) := Svo; + Scope_Suppress.Overflow_Mode_General := Svg; + Scope_Suppress.Overflow_Mode_Assertions := Sva; + end Reexpand; + + -- Start of processing for Minimize_Eliminate_Overflows + + begin + -- Case where we do not have a signed integer arithmetic operation + + if not Is_Signed_Integer_Arithmetic_Op (N) then + + -- Use the normal Determine_Range routine to get the range. We + -- don't require operands to be valid, invalid values may result in + -- rubbish results where the result has not been properly checked for + -- overflow, that's fine. + + Determine_Range (N, OK, Lo, Hi, Assume_Valid => False); + + -- If Determine_Range did not work (can this in fact happen? Not + -- clear but might as well protect), use type bounds. + + if not OK then + Lo := Intval (Type_Low_Bound (Base_Type (Etype (N)))); + Hi := Intval (Type_High_Bound (Base_Type (Etype (N)))); + end if; + + -- If we don't have a binary operator, all we have to do is to set + -- the Hi/Lo range, so we are done. + + return; + + -- Processing for if expression + + elsif Nkind (N) = N_If_Expression then + declare + Then_DE : constant Node_Id := Next (First (Expressions (N))); + Else_DE : constant Node_Id := Next (Then_DE); + + begin + Bignum_Operands := False; + + Minimize_Eliminate_Overflows + (Then_DE, Lo, Hi, Top_Level => False); + + if Lo = No_Uint then + Bignum_Operands := True; + end if; + + Minimize_Eliminate_Overflows + (Else_DE, Rlo, Rhi, Top_Level => False); + + if Rlo = No_Uint then + Bignum_Operands := True; + else + Long_Long_Integer_Operands := + Etype (Then_DE) = LLIB or else Etype (Else_DE) = LLIB; + + Min (Lo, Rlo); + Max (Hi, Rhi); + end if; + + -- If at least one of our operands is now Bignum, we must rebuild + -- the if expression to use Bignum operands. We will analyze the + -- rebuilt if expression with overflow checks off, since once we + -- are in bignum mode, we are all done with overflow checks. + + if Bignum_Operands then + Rewrite (N, + Make_If_Expression (Loc, + Expressions => New_List ( + Remove_Head (Expressions (N)), + Convert_To_Bignum (Then_DE), + Convert_To_Bignum (Else_DE)), + Is_Elsif => Is_Elsif (N))); + + Reanalyze (RTE (RE_Bignum), Suppress => True); + + -- If we have no Long_Long_Integer operands, then we are in result + -- range, since it means that none of our operands felt the need + -- to worry about overflow (otherwise it would have already been + -- converted to long long integer or bignum). We reexpand to + -- complete the expansion of the if expression (but we do not + -- need to reanalyze). + + elsif not Long_Long_Integer_Operands then + Set_Do_Overflow_Check (N, False); + Reexpand; + + -- Otherwise convert us to long long integer mode. Note that we + -- don't need any further overflow checking at this level. + + else + Convert_To_And_Rewrite (LLIB, Then_DE); + Convert_To_And_Rewrite (LLIB, Else_DE); + Set_Etype (N, LLIB); + + -- Now reanalyze with overflow checks off + + Set_Do_Overflow_Check (N, False); + Reanalyze (LLIB, Suppress => True); + end if; + end; + + return; + + -- Here for case expression + + elsif Nkind (N) = N_Case_Expression then + Bignum_Operands := False; + Long_Long_Integer_Operands := False; + + declare + Alt : Node_Id; + + begin + -- Loop through expressions applying recursive call + + Alt := First (Alternatives (N)); + while Present (Alt) loop + declare + Aexp : constant Node_Id := Expression (Alt); + + begin + Minimize_Eliminate_Overflows + (Aexp, Lo, Hi, Top_Level => False); + + if Lo = No_Uint then + Bignum_Operands := True; + elsif Etype (Aexp) = LLIB then + Long_Long_Integer_Operands := True; + end if; + end; + + Next (Alt); + end loop; + + -- If we have no bignum or long long integer operands, it means + -- that none of our dependent expressions could raise overflow. + -- In this case, we simply return with no changes except for + -- resetting the overflow flag, since we are done with overflow + -- checks for this node. We will reexpand to get the needed + -- expansion for the case expression, but we do not need to + -- reanalyze, since nothing has changed. + + if not (Bignum_Operands or Long_Long_Integer_Operands) then + Set_Do_Overflow_Check (N, False); + Reexpand (Suppress => True); + + -- Otherwise we are going to rebuild the case expression using + -- either bignum or long long integer operands throughout. + + else + declare + Rtype : Entity_Id; + New_Alts : List_Id; + New_Exp : Node_Id; + + begin + New_Alts := New_List; + Alt := First (Alternatives (N)); + while Present (Alt) loop + if Bignum_Operands then + New_Exp := Convert_To_Bignum (Expression (Alt)); + Rtype := RTE (RE_Bignum); + else + New_Exp := Convert_To (LLIB, Expression (Alt)); + Rtype := LLIB; + end if; + + Append_To (New_Alts, + Make_Case_Expression_Alternative (Sloc (Alt), + Actions => No_List, + Discrete_Choices => Discrete_Choices (Alt), + Expression => New_Exp)); + + Next (Alt); + end loop; + + Rewrite (N, + Make_Case_Expression (Loc, + Expression => Expression (N), + Alternatives => New_Alts)); + + Reanalyze (Rtype, Suppress => True); + end; + end if; + end; + + return; + end if; + + -- If we have an arithmetic operator we make recursive calls on the + -- operands to get the ranges (and to properly process the subtree + -- that lies below us). + + Minimize_Eliminate_Overflows + (Right_Opnd (N), Rlo, Rhi, Top_Level => False); + + if Binary then + Minimize_Eliminate_Overflows + (Left_Opnd (N), Llo, Lhi, Top_Level => False); + end if; + + -- Record if we have Long_Long_Integer operands + + Long_Long_Integer_Operands := + Etype (Right_Opnd (N)) = LLIB + or else (Binary and then Etype (Left_Opnd (N)) = LLIB); + + -- If either operand is a bignum, then result will be a bignum and we + -- don't need to do any range analysis. As previously discussed we could + -- do range analysis in such cases, but it could mean working with giant + -- numbers at compile time for very little gain (the number of cases + -- in which we could slip back from bignum mode is small). + + if Rlo = No_Uint or else (Binary and then Llo = No_Uint) then + Lo := No_Uint; + Hi := No_Uint; + Bignum_Operands := True; + + -- Otherwise compute result range + + else + Bignum_Operands := False; + + case Nkind (N) is + + -- Absolute value + + when N_Op_Abs => + Lo := Uint_0; + Hi := UI_Max (abs Rlo, abs Rhi); + + -- Addition + + when N_Op_Add => + Lo := Llo + Rlo; + Hi := Lhi + Rhi; + + -- Division + + when N_Op_Divide => + + -- If the right operand can only be zero, set 0..0 + + if Rlo = 0 and then Rhi = 0 then + Lo := Uint_0; + Hi := Uint_0; + + -- Possible bounds of division must come from dividing end + -- values of the input ranges (four possibilities), provided + -- zero is not included in the possible values of the right + -- operand. + + -- Otherwise, we just consider two intervals of values for + -- the right operand: the interval of negative values (up to + -- -1) and the interval of positive values (starting at 1). + -- Since division by 1 is the identity, and division by -1 + -- is negation, we get all possible bounds of division in that + -- case by considering: + -- - all values from the division of end values of input + -- ranges; + -- - the end values of the left operand; + -- - the negation of the end values of the left operand. + + else + declare + Mrk : constant Uintp.Save_Mark := Mark; + -- Mark so we can release the RR and Ev values + + Ev1 : Uint; + Ev2 : Uint; + Ev3 : Uint; + Ev4 : Uint; + + begin + -- Discard extreme values of zero for the divisor, since + -- they will simply result in an exception in any case. + + if Rlo = 0 then + Rlo := Uint_1; + elsif Rhi = 0 then + Rhi := -Uint_1; + end if; + + -- Compute possible bounds coming from dividing end + -- values of the input ranges. + + Ev1 := Llo / Rlo; + Ev2 := Llo / Rhi; + Ev3 := Lhi / Rlo; + Ev4 := Lhi / Rhi; + + Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4)); + Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4)); + + -- If the right operand can be both negative or positive, + -- include the end values of the left operand in the + -- extreme values, as well as their negation. + + if Rlo < 0 and then Rhi > 0 then + Ev1 := Llo; + Ev2 := -Llo; + Ev3 := Lhi; + Ev4 := -Lhi; + + Min (Lo, + UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4))); + Max (Hi, + UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4))); + end if; + + -- Release the RR and Ev values + + Release_And_Save (Mrk, Lo, Hi); + end; + end if; + + -- Exponentiation + + when N_Op_Expon => + + -- Discard negative values for the exponent, since they will + -- simply result in an exception in any case. + + if Rhi < 0 then + Rhi := Uint_0; + elsif Rlo < 0 then + Rlo := Uint_0; + end if; + + -- Estimate number of bits in result before we go computing + -- giant useless bounds. Basically the number of bits in the + -- result is the number of bits in the base multiplied by the + -- value of the exponent. If this is big enough that the result + -- definitely won't fit in Long_Long_Integer, switch to bignum + -- mode immediately, and avoid computing giant bounds. + + -- The comparison here is approximate, but conservative, it + -- only clicks on cases that are sure to exceed the bounds. + + if Num_Bits (UI_Max (abs Llo, abs Lhi)) * Rhi + 1 > 100 then + Lo := No_Uint; + Hi := No_Uint; + + -- If right operand is zero then result is 1 + + elsif Rhi = 0 then + Lo := Uint_1; + Hi := Uint_1; + + else + -- High bound comes either from exponentiation of largest + -- positive value to largest exponent value, or from + -- the exponentiation of most negative value to an + -- even exponent. + + declare + Hi1, Hi2 : Uint; + + begin + if Lhi > 0 then + Hi1 := Lhi ** Rhi; + else + Hi1 := Uint_0; + end if; + + if Llo < 0 then + if Rhi mod 2 = 0 then + Hi2 := Llo ** Rhi; + else + Hi2 := Llo ** (Rhi - 1); + end if; + else + Hi2 := Uint_0; + end if; + + Hi := UI_Max (Hi1, Hi2); + end; + + -- Result can only be negative if base can be negative + + if Llo < 0 then + if Rhi mod 2 = 0 then + Lo := Llo ** (Rhi - 1); + else + Lo := Llo ** Rhi; + end if; + + -- Otherwise low bound is minimum ** minimum + + else + Lo := Llo ** Rlo; + end if; + end if; + + -- Negation + + when N_Op_Minus => + Lo := -Rhi; + Hi := -Rlo; + + -- Mod + + when N_Op_Mod => + declare + Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1; + -- This is the maximum absolute value of the result + + begin + Lo := Uint_0; + Hi := Uint_0; + + -- The result depends only on the sign and magnitude of + -- the right operand, it does not depend on the sign or + -- magnitude of the left operand. + + if Rlo < 0 then + Lo := -Maxabs; + end if; + + if Rhi > 0 then + Hi := Maxabs; + end if; + end; + + -- Multiplication + + when N_Op_Multiply => + + -- Possible bounds of multiplication must come from multiplying + -- end values of the input ranges (four possibilities). + + declare + Mrk : constant Uintp.Save_Mark := Mark; + -- Mark so we can release the Ev values + + Ev1 : constant Uint := Llo * Rlo; + Ev2 : constant Uint := Llo * Rhi; + Ev3 : constant Uint := Lhi * Rlo; + Ev4 : constant Uint := Lhi * Rhi; + + begin + Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4)); + Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4)); + + -- Release the Ev values + + Release_And_Save (Mrk, Lo, Hi); + end; + + -- Plus operator (affirmation) + + when N_Op_Plus => + Lo := Rlo; + Hi := Rhi; + + -- Remainder + + when N_Op_Rem => + declare + Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1; + -- This is the maximum absolute value of the result. Note + -- that the result range does not depend on the sign of the + -- right operand. + + begin + Lo := Uint_0; + Hi := Uint_0; + + -- Case of left operand negative, which results in a range + -- of -Maxabs .. 0 for those negative values. If there are + -- no negative values then Lo value of result is always 0. + + if Llo < 0 then + Lo := -Maxabs; + end if; + + -- Case of left operand positive + + if Lhi > 0 then + Hi := Maxabs; + end if; + end; + + -- Subtract + + when N_Op_Subtract => + Lo := Llo - Rhi; + Hi := Lhi - Rlo; + + -- Nothing else should be possible + + when others => + raise Program_Error; + end case; + end if; + + -- Here for the case where we have not rewritten anything (no bignum + -- operands or long long integer operands), and we know the result. + -- If we know we are in the result range, and we do not have Bignum + -- operands or Long_Long_Integer operands, we can just reexpand with + -- overflow checks turned off (since we know we cannot have overflow). + -- As always the reexpansion is required to complete expansion of the + -- operator, but we do not need to reanalyze, and we prevent recursion + -- by suppressing the check. + + if not (Bignum_Operands or Long_Long_Integer_Operands) + and then In_Result_Range + then + Set_Do_Overflow_Check (N, False); + Reexpand (Suppress => True); + return; + + -- Here we know that we are not in the result range, and in the general + -- case we will move into either the Bignum or Long_Long_Integer domain + -- to compute the result. However, there is one exception. If we are + -- at the top level, and we do not have Bignum or Long_Long_Integer + -- operands, we will have to immediately convert the result back to + -- the result type, so there is no point in Bignum/Long_Long_Integer + -- fiddling. + + elsif Top_Level + and then not (Bignum_Operands or Long_Long_Integer_Operands) + + -- One further refinement. If we are at the top level, but our parent + -- is a type conversion, then go into bignum or long long integer node + -- since the result will be converted to that type directly without + -- going through the result type, and we may avoid an overflow. This + -- is the case for example of Long_Long_Integer (A ** 4), where A is + -- of type Integer, and the result A ** 4 fits in Long_Long_Integer + -- but does not fit in Integer. + + and then Nkind (Parent (N)) /= N_Type_Conversion + then + -- Here keep original types, but we need to complete analysis + + -- One subtlety. We can't just go ahead and do an analyze operation + -- here because it will cause recursion into the whole MINIMIZED/ + -- ELIMINATED overflow processing which is not what we want. Here + -- we are at the top level, and we need a check against the result + -- mode (i.e. we want to use STRICT mode). So do exactly that. + -- Also, we have not modified the node, so this is a case where + -- we need to reexpand, but not reanalyze. + + Reexpand; + return; + + -- Cases where we do the operation in Bignum mode. This happens either + -- because one of our operands is in Bignum mode already, or because + -- the computed bounds are outside the bounds of Long_Long_Integer, + -- which in some cases can be indicated by Hi and Lo being No_Uint. + + -- Note: we could do better here and in some cases switch back from + -- Bignum mode to normal mode, e.g. big mod 2 must be in the range + -- 0 .. 1, but the cases are rare and it is not worth the effort. + -- Failing to do this switching back is only an efficiency issue. + + elsif Lo = No_Uint or else Lo < LLLo or else Hi > LLHi then + + -- OK, we are definitely outside the range of Long_Long_Integer. The + -- question is whether to move to Bignum mode, or stay in the domain + -- of Long_Long_Integer, signalling that an overflow check is needed. + + -- Obviously in MINIMIZED mode we stay with LLI, since we are not in + -- the Bignum business. In ELIMINATED mode, we will normally move + -- into Bignum mode, but there is an exception if neither of our + -- operands is Bignum now, and we are at the top level (Top_Level + -- set True). In this case, there is no point in moving into Bignum + -- mode to prevent overflow if the caller will immediately convert + -- the Bignum value back to LLI with an overflow check. It's more + -- efficient to stay in LLI mode with an overflow check (if needed) + + if Check_Mode = Minimized + or else (Top_Level and not Bignum_Operands) + then + if Do_Overflow_Check (N) then + Enable_Overflow_Check (N); + end if; + + -- The result now has to be in Long_Long_Integer mode, so adjust + -- the possible range to reflect this. Note these calls also + -- change No_Uint values from the top level case to LLI bounds. + + Max (Lo, LLLo); + Min (Hi, LLHi); + + -- Otherwise we are in ELIMINATED mode and we switch to Bignum mode + + else + pragma Assert (Check_Mode = Eliminated); + + declare + Fent : Entity_Id; + Args : List_Id; + + begin + case Nkind (N) is + when N_Op_Abs => + Fent := RTE (RE_Big_Abs); + + when N_Op_Add => + Fent := RTE (RE_Big_Add); + + when N_Op_Divide => + Fent := RTE (RE_Big_Div); + + when N_Op_Expon => + Fent := RTE (RE_Big_Exp); + + when N_Op_Minus => + Fent := RTE (RE_Big_Neg); + + when N_Op_Mod => + Fent := RTE (RE_Big_Mod); + + when N_Op_Multiply => + Fent := RTE (RE_Big_Mul); + + when N_Op_Rem => + Fent := RTE (RE_Big_Rem); + + when N_Op_Subtract => + Fent := RTE (RE_Big_Sub); + + -- Anything else is an internal error, this includes the + -- N_Op_Plus case, since how can plus cause the result + -- to be out of range if the operand is in range? + + when others => + raise Program_Error; + end case; + + -- Construct argument list for Bignum call, converting our + -- operands to Bignum form if they are not already there. + + Args := New_List; + + if Binary then + Append_To (Args, Convert_To_Bignum (Left_Opnd (N))); + end if; + + Append_To (Args, Convert_To_Bignum (Right_Opnd (N))); + + -- Now rewrite the arithmetic operator with a call to the + -- corresponding bignum function. + + Rewrite (N, + Make_Function_Call (Loc, + Name => New_Occurrence_Of (Fent, Loc), + Parameter_Associations => Args)); + Reanalyze (RTE (RE_Bignum), Suppress => True); + + -- Indicate result is Bignum mode + + Lo := No_Uint; + Hi := No_Uint; + return; + end; + end if; + + -- Otherwise we are in range of Long_Long_Integer, so no overflow + -- check is required, at least not yet. + + else + Set_Do_Overflow_Check (N, False); + end if; + + -- Here we are not in Bignum territory, but we may have long long + -- integer operands that need special handling. First a special check: + -- If an exponentiation operator exponent is of type Long_Long_Integer, + -- it means we converted it to prevent overflow, but exponentiation + -- requires a Natural right operand, so convert it back to Natural. + -- This conversion may raise an exception which is fine. + + if Nkind (N) = N_Op_Expon and then Etype (Right_Opnd (N)) = LLIB then + Convert_To_And_Rewrite (Standard_Natural, Right_Opnd (N)); + end if; + + -- Here we will do the operation in Long_Long_Integer. We do this even + -- if we know an overflow check is required, better to do this in long + -- long integer mode, since we are less likely to overflow. + + -- Convert right or only operand to Long_Long_Integer, except that + -- we do not touch the exponentiation right operand. + + if Nkind (N) /= N_Op_Expon then + Convert_To_And_Rewrite (LLIB, Right_Opnd (N)); + end if; + + -- Convert left operand to Long_Long_Integer for binary case + + if Binary then + Convert_To_And_Rewrite (LLIB, Left_Opnd (N)); + end if; + + -- Reset node to unanalyzed + + Set_Analyzed (N, False); + Set_Etype (N, Empty); + Set_Entity (N, Empty); + + -- Now analyze this new node. This reanalysis will complete processing + -- for the node. In particular we will complete the expansion of an + -- exponentiation operator (e.g. changing A ** 2 to A * A), and also + -- we will complete any division checks (since we have not changed the + -- setting of the Do_Division_Check flag). + + -- We do this reanalysis in STRICT mode to avoid recursion into the + -- MINIMIZED/ELIMINATED handling, since we are now done with that. + + declare + SG : constant Overflow_Mode_Type := + Scope_Suppress.Overflow_Mode_General; + SA : constant Overflow_Mode_Type := + Scope_Suppress.Overflow_Mode_Assertions; + + begin + Scope_Suppress.Overflow_Mode_General := Strict; + Scope_Suppress.Overflow_Mode_Assertions := Strict; + + if not Do_Overflow_Check (N) then + Reanalyze (LLIB, Suppress => True); + else + Reanalyze (LLIB); + end if; + + Scope_Suppress.Overflow_Mode_General := SG; + Scope_Suppress.Overflow_Mode_Assertions := SA; + end; + end Minimize_Eliminate_Overflows; + + ------------------------- + -- Overflow_Check_Mode -- + ------------------------- + + function Overflow_Check_Mode return Overflow_Mode_Type is + begin + if In_Assertion_Expr = 0 then + return Scope_Suppress.Overflow_Mode_General; + else + return Scope_Suppress.Overflow_Mode_Assertions; + end if; + end Overflow_Check_Mode; + + -------------------------------- + -- 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.Suppress (Overflow_Check); + end if; + end Overflow_Checks_Suppressed; + + --------------------------------- + -- Predicate_Checks_Suppressed -- + --------------------------------- + + function Predicate_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, Predicate_Check); + else + return Scope_Suppress.Suppress (Predicate_Check); + end if; + end Predicate_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.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.Suppress (Range_Check) + or + Scope_Suppress.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 two checks ??? + -- This is really worrisome, are we really discarding 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 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 if 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; + + 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 Nkind (HB) = N_Identifier + and then Ekind (Entity (HB)) = E_Discriminant + then + HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc); + 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 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 => + Convert_To (Base_Type (Etype (HB)), + Duplicate_Subexpr_No_Checks (HB)), + Right_Opnd => + Convert_To (Base_Type (Etype (LB)), + 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.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) + and then Checks_May_Be_Suppressed (E) + then + return Is_Check_Suppressed (E, Tag_Check); + else + return Scope_Suppress.Suppress (Tag_Check); + end if; + 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.Suppress (Validity_Check); + end if; + end Validity_Checks_Suppressed; + +end Checks; |