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Diffstat (limited to 'gcc-4.8/gcc/ada/checks.adb')
| -rw-r--r-- | gcc-4.8/gcc/ada/checks.adb | 9295 |
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diff --git a/gcc-4.8/gcc/ada/checks.adb b/gcc-4.8/gcc/ada/checks.adb deleted file mode 100644 index 7afabd1c2..000000000 --- a/gcc-4.8/gcc/ada/checks.adb +++ /dev/null @@ -1,9295 +0,0 @@ ------------------------------------------------------------------------------- --- -- --- 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 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_Tss; use Exp_Tss; -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 Targparm; use Targparm; -with Tbuild; use Tbuild; -with Ttypes; use Ttypes; -with Urealp; use Urealp; -with Validsw; use Validsw; - -package body Checks is - - -- General note: many of these routines are concerned with generating - -- checking code to make sure that constraint error is raised at runtime. - -- Clearly this code is only needed if the expander is active, since - -- otherwise we will not be generating code or going into the runtime - -- execution anyway. - - -- We therefore disconnect most of these checks if the expander is - -- inactive. This has the additional benefit that we do not need to - -- worry about the tree being messed up by previous errors (since errors - -- turn off expansion anyway). - - -- There are a few exceptions to the above rule. For instance routines - -- such as Apply_Scalar_Range_Check that do not insert any code can be - -- safely called even when the Expander is inactive (but Errors_Detected - -- is 0). The benefit of executing this code when expansion is off, is - -- the ability to emit constraint error warning for static expressions - -- even when we are not generating code. - - ------------------------------------- - -- Suppression of Redundant Checks -- - ------------------------------------- - - -- This unit implements a limited circuit for removal of redundant - -- checks. The processing is based on a tracing of simple sequential - -- flow. For any sequence of statements, we save expressions that are - -- marked to be checked, and then if the same expression appears later - -- with the same check, then under certain circumstances, the second - -- check can be suppressed. - - -- Basically, we can suppress the check if we know for certain that - -- the previous expression has been elaborated (together with its - -- check), and we know that the exception frame is the same, and that - -- nothing has happened to change the result of the exception. - - -- Let us examine each of these three conditions in turn to describe - -- how we ensure that this condition is met. - - -- First, we need to know for certain that the previous expression has - -- been executed. This is done principally by the mechanism of calling - -- Conditional_Statements_Begin at the start of any statement sequence - -- and Conditional_Statements_End at the end. The End call causes all - -- checks remembered since the Begin call to be discarded. This does - -- miss a few cases, notably the case of a nested BEGIN-END block with - -- no exception handlers. But the important thing is to be conservative. - -- The other protection is that all checks are discarded if a label - -- is encountered, since then the assumption of sequential execution - -- is violated, and we don't know enough about the flow. - - -- Second, we need to know that the exception frame is the same. We - -- do this by killing all remembered checks when we enter a new frame. - -- Again, that's over-conservative, but generally the cases we can help - -- with are pretty local anyway (like the body of a loop for example). - - -- Third, we must be sure to forget any checks which are no longer valid. - -- This is done by two mechanisms, first the Kill_Checks_Variable call is - -- used to note any changes to local variables. We only attempt to deal - -- with checks involving local variables, so we do not need to worry - -- about global variables. Second, a call to any non-global procedure - -- causes us to abandon all stored checks, since such a all may affect - -- the values of any local variables. - - -- The following define the data structures used to deal with remembering - -- checks so that redundant checks can be eliminated as described above. - - -- Right now, the only expressions that we deal with are of the form of - -- simple local objects (either declared locally, or IN parameters) or - -- such objects plus/minus a compile time known constant. We can do - -- more later on if it seems worthwhile, but this catches many simple - -- cases in practice. - - -- The following record type reflects a single saved check. An entry - -- is made in the stack of saved checks if and only if the expression - -- has been elaborated with the indicated checks. - - type Saved_Check is record - Killed : Boolean; - -- Set True if entry is killed by Kill_Checks - - Entity : Entity_Id; - -- The entity involved in the expression that is checked - - Offset : Uint; - -- A compile time value indicating the result of adding or - -- subtracting a compile time value. This value is to be - -- added to the value of the Entity. A value of zero is - -- used for the case of a simple entity reference. - - Check_Type : Character; - -- This is set to 'R' for a range check (in which case Target_Type - -- is set to the target type for the range check) or to 'O' for an - -- overflow check (in which case Target_Type is set to Empty). - - Target_Type : Entity_Id; - -- Used only if Do_Range_Check is set. Records the target type for - -- the check. We need this, because a check is a duplicate only if - -- it has the same target type (or more accurately one with a - -- range that is smaller or equal to the stored target type of a - -- saved check). - end record; - - -- The following table keeps track of saved checks. Rather than use an - -- extensible table. We just use a table of fixed size, and we discard - -- any saved checks that do not fit. That's very unlikely to happen and - -- this is only an optimization in any case. - - Saved_Checks : array (Int range 1 .. 200) of Saved_Check; - -- Array of saved checks - - Num_Saved_Checks : Nat := 0; - -- Number of saved checks - - -- The following stack keeps track of statement ranges. It is treated - -- as a stack. When Conditional_Statements_Begin is called, an entry - -- is pushed onto this stack containing the value of Num_Saved_Checks - -- at the time of the call. Then when Conditional_Statements_End is - -- called, this value is popped off and used to reset Num_Saved_Checks. - - -- Note: again, this is a fixed length stack with a size that should - -- always be fine. If the value of the stack pointer goes above the - -- limit, then we just forget all saved checks. - - Saved_Checks_Stack : array (Int range 1 .. 100) of Nat; - Saved_Checks_TOS : Nat := 0; - - ----------------------- - -- Local Subprograms -- - ----------------------- - - procedure Apply_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 Full_Expander_Active then - return; - end if; - - -- No check if short circuiting makes check unnecessary - - if not Check_Needed (P, Access_Check) then - return; - end if; - - -- No check if accessing the Offset_To_Top component of a dispatch - -- table. They are safe by construction. - - if Tagged_Type_Expansion - and then Present (Etype (P)) - and then RTU_Loaded (Ada_Tags) - and then RTE_Available (RE_Offset_To_Top_Ptr) - and then Etype (P) = RTE (RE_Offset_To_Top_Ptr) - then - return; - end if; - - -- Otherwise go ahead and install the check - - Install_Null_Excluding_Check (P); - end Apply_Access_Check; - - ------------------------------- - -- Apply_Accessibility_Check -- - ------------------------------- - - procedure Apply_Accessibility_Check - (N : Node_Id; - Typ : Entity_Id; - Insert_Node : Node_Id) - is - Loc : constant Source_Ptr := Sloc (N); - Param_Ent : Entity_Id := Param_Entity (N); - Param_Level : Node_Id; - Type_Level : Node_Id; - - begin - if Ada_Version >= Ada_2012 - and then not Present (Param_Ent) - and then Is_Entity_Name (N) - and then Ekind_In (Entity (N), E_Constant, E_Variable) - and then Present (Effective_Extra_Accessibility (Entity (N))) - then - Param_Ent := Entity (N); - while Present (Renamed_Object (Param_Ent)) loop - - -- Renamed_Object must return an Entity_Name here - -- because of preceding "Present (E_E_A (...))" test. - - Param_Ent := Entity (Renamed_Object (Param_Ent)); - end loop; - end if; - - if Inside_A_Generic then - return; - - -- Only apply the run-time check if the access parameter has an - -- associated extra access level parameter and when the level of the - -- type is less deep than the level of the access parameter, and - -- accessibility checks are not suppressed. - - elsif Present (Param_Ent) - and then Present (Extra_Accessibility (Param_Ent)) - and then UI_Gt (Object_Access_Level (N), - Deepest_Type_Access_Level (Typ)) - and then not Accessibility_Checks_Suppressed (Param_Ent) - and then not Accessibility_Checks_Suppressed (Typ) - then - Param_Level := - New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc); - - Type_Level := - Make_Integer_Literal (Loc, Deepest_Type_Access_Level (Typ)); - - -- Raise Program_Error if the accessibility level of the access - -- parameter is deeper than the level of the target access type. - - Insert_Action (Insert_Node, - Make_Raise_Program_Error (Loc, - Condition => - Make_Op_Gt (Loc, - Left_Opnd => Param_Level, - Right_Opnd => Type_Level), - Reason => PE_Accessibility_Check_Failed)); - - Analyze_And_Resolve (N); - end if; - end Apply_Accessibility_Check; - - -------------------------------- - -- Apply_Address_Clause_Check -- - -------------------------------- - - procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is - 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); - 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 Full_Expander_Active - or else (Present (Parent (N)) - and then Nkind (Parent (N)) = N_Type_Conversion - and then Integer_Promotion_Possible (Parent (N))) - or else - (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size) - then - return; - end if; - - -- Otherwise, generate the full general code for front end overflow - -- detection, which works by doing arithmetic in a larger type: - - -- x op y - - -- is expanded into - - -- Typ (Checktyp (x) op Checktyp (y)); - - -- where Typ is the type of the original expression, and Checktyp is - -- an integer type of sufficient length to hold the largest possible - -- result. - - -- If the size of check type exceeds the size of Long_Long_Integer, - -- we use a different approach, expanding to: - - -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y))) - - -- where xxx is Add, Multiply or Subtract as appropriate - - -- Find check type if one exists - - if Dsiz <= Standard_Integer_Size then - Ctyp := Standard_Integer; - - elsif Dsiz <= Standard_Long_Long_Integer_Size then - Ctyp := Standard_Long_Long_Integer; - - -- No check type exists, use runtime call - - else - if Nkind (N) = N_Op_Add then - Cent := RE_Add_With_Ovflo_Check; - - elsif Nkind (N) = N_Op_Multiply then - Cent := RE_Multiply_With_Ovflo_Check; - - else - pragma Assert (Nkind (N) = N_Op_Subtract); - Cent := RE_Subtract_With_Ovflo_Check; - end if; - - Rewrite (N, - OK_Convert_To (Typ, - Make_Function_Call (Loc, - Name => New_Reference_To (RTE (Cent), Loc), - Parameter_Associations => New_List ( - OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)), - OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N)))))); - - Analyze_And_Resolve (N, Typ); - return; - end if; - - -- If we fall through, we have the case where we do the arithmetic - -- in the next higher type and get the check by conversion. In these - -- cases Ctyp is set to the type to be used as the check type. - - Opnod := Relocate_Node (N); - - Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod)); - - Analyze (Opnd); - Set_Etype (Opnd, Ctyp); - Set_Analyzed (Opnd, True); - Set_Left_Opnd (Opnod, Opnd); - - Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod)); - - Analyze (Opnd); - Set_Etype (Opnd, Ctyp); - Set_Analyzed (Opnd, True); - Set_Right_Opnd (Opnod, Opnd); - - -- The type of the operation changes to the base type of the check - -- type, and we reset the overflow check indication, since clearly no - -- overflow is possible now that we are using a double length type. - -- We also set the Analyzed flag to avoid a recursive attempt to - -- expand the node. - - Set_Etype (Opnod, Base_Type (Ctyp)); - Set_Do_Overflow_Check (Opnod, False); - Set_Analyzed (Opnod, True); - - -- Now build the outer conversion - - Opnd := OK_Convert_To (Typ, Opnod); - Analyze (Opnd); - Set_Etype (Opnd, Typ); - - -- In the discrete type case, we directly generate the range check - -- for the outer operand. This range check will implement the - -- required overflow check. - - if Is_Discrete_Type (Typ) then - Rewrite (N, Opnd); - Generate_Range_Check - (Expression (N), Typ, CE_Overflow_Check_Failed); - - -- For other types, we enable overflow checking on the conversion, - -- after setting the node as analyzed to prevent recursive attempts - -- to expand the conversion node. - - else - Set_Analyzed (Opnd, True); - Enable_Overflow_Check (Opnd); - Rewrite (N, Opnd); - end if; - - exception - when RE_Not_Available => - return; - end; - end Apply_Arithmetic_Overflow_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 Full_Expander_Active - or else Discriminant_Checks_Suppressed (T_Typ) - then - return; - end if; - - -- No discriminant checks necessary for an access when expression is - -- statically Null. This is not only an optimization, it is fundamental - -- because otherwise discriminant checks may be generated in init procs - -- for types containing an access to a not-yet-frozen record, causing a - -- deadly forward reference. - - -- Also, if the expression is of an access type whose designated type is - -- incomplete, then the access value must be null and we suppress the - -- check. - - if Known_Null (N) then - return; - - elsif Is_Access_Type (S_Typ) then - S_Typ := Designated_Type (S_Typ); - - if Ekind (S_Typ) = E_Incomplete_Type then - return; - end if; - end if; - - -- If an assignment target is present, then we need to generate the - -- actual subtype if the target is a parameter or aliased object with - -- an unconstrained nominal subtype. - - -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual - -- subtype to the parameter and dereference cases, since other aliased - -- objects are unconstrained (unless the nominal subtype is explicitly - -- constrained). - - if Present (Lhs) - and then (Present (Param_Entity (Lhs)) - or else (Ada_Version < Ada_2005 - and then not Is_Constrained (T_Typ) - and then Is_Aliased_View (Lhs) - and then not Is_Aliased_Unconstrained_Component) - or else (Ada_Version >= Ada_2005 - and then not Is_Constrained (T_Typ) - and then Denotes_Explicit_Dereference (Lhs) - and then Nkind (Original_Node (Lhs)) /= - N_Function_Call)) - then - T_Typ := Get_Actual_Subtype (Lhs); - end if; - - -- Nothing to do if the type is unconstrained (this is the case where - -- the actual subtype in the RM sense of N is unconstrained and no check - -- is required). - - if not Is_Constrained (T_Typ) then - return; - - -- Ada 2005: nothing to do if the type is one for which there is a - -- partial view that is constrained. - - elsif Ada_Version >= Ada_2005 - and then Effectively_Has_Constrained_Partial_View - (Typ => Base_Type (T_Typ), - Scop => Current_Scope) - then - return; - end if; - - -- Nothing to do if the type is an Unchecked_Union - - if Is_Unchecked_Union (Base_Type (T_Typ)) then - return; - end if; - - -- Suppress checks if the subtypes are the same. the check must be - -- preserved in an assignment to a formal, because the constraint is - -- given by the actual. - - if Nkind (Original_Node (N)) /= N_Allocator - and then (No (Lhs) - or else not Is_Entity_Name (Lhs) - or else No (Param_Entity (Lhs))) - then - if (Etype (N) = Typ - or else (Do_Access and then Designated_Type (Typ) = S_Typ)) - and then not Is_Aliased_View (Lhs) - then - return; - end if; - - -- We can also eliminate checks on allocators with a subtype mark that - -- coincides with the context type. The context type may be a subtype - -- without a constraint (common case, a generic actual). - - elsif Nkind (Original_Node (N)) = N_Allocator - and then Is_Entity_Name (Expression (Original_Node (N))) - then - declare - Alloc_Typ : constant Entity_Id := - Entity (Expression (Original_Node (N))); - - begin - if Alloc_Typ = T_Typ - or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration - and then Is_Entity_Name ( - Subtype_Indication (Parent (T_Typ))) - and then Alloc_Typ = Base_Type (T_Typ)) - - then - return; - end if; - end; - end if; - - -- See if we have a case where the types are both constrained, and all - -- the constraints are constants. In this case, we can do the check - -- successfully at compile time. - - -- We skip this check for the case where the node is 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 Full_Expander_Active - and then not Backend_Divide_Checks_On_Target - and then Check_Needed (Right, Division_Check) - then - Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True); - - -- 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 Full_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 - 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 - 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. - - ------------------------ - -- 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; - - -- Local variables - - Loc : constant Source_Ptr := Sloc (Call); - Actual_1 : Node_Id; - Actual_2 : Node_Id; - Check : Node_Id; - Cond : Node_Id; - Formal_1 : Entity_Id; - Formal_2 : Entity_Id; - - -- Start of processing for Apply_Parameter_Aliasing_Checks - - begin - Cond := 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 - -- Generate: - -- Actual_1'Overlaps_Storage (Actual_2) - - Check := - 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)))); - - if No (Cond) then - Cond := Check; - else - Cond := - Make_And_Then (Loc, - Left_Opnd => Cond, - Right_Opnd => Check); - end if; - 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 the check right before the call - - if Present (Cond) then - Insert_Action (Call, - Make_Raise_Program_Error (Loc, - Condition => Cond, - Reason => PE_Explicit_Raise)); - 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_Reference_To (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 - - -- A predicate check does not apply within internally generated - -- subprograms, such as TSS functions. - - S := Current_Scope; - while Present (S) and then not Is_Subprogram (S) loop - S := Scope (S); - end loop; - - if Present (S) and then Get_TSS_Name (S) /= TSS_Null 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 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 predicate is a static predicate and the operand is - -- static, the predicate must be evaluated statically. If the - -- evaluation fails this is a static constraint error. This check - -- is disabled in -gnatc mode, because the compiler is incapable - -- of evaluating static expressions in that case. - - if Is_OK_Static_Expression (N) then - if Present (Static_Predicate (Typ)) then - if Operating_Mode < Generate_Code - or else Eval_Static_Predicate_Check (N, Typ) - then - return; - else - Error_Msg_NE - ("static expression fails static predicate check on&", - N, Typ); - end if; - end if; - end if; - - 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 - if not Full_Expander_Active then - return; - end if; - - R_Result := - Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty); - - for J in 1 .. 2 loop - R_Cno := R_Result (J); - exit when No (R_Cno); - - -- A length check may mention an Itype which is attached to a - -- subsequent node. At the top level in a package this can cause - -- an order-of-elaboration problem, so we make sure that the itype - -- is referenced now. - - if Ekind (Current_Scope) = E_Package - and then Is_Compilation_Unit (Current_Scope) - then - Ensure_Defined (Target_Typ, Ck_Node); - - if Present (Source_Typ) then - Ensure_Defined (Source_Typ, Ck_Node); - - elsif Is_Itype (Etype (Ck_Node)) then - Ensure_Defined (Etype (Ck_Node), Ck_Node); - end if; - end if; - - -- If the item is a conditional raise of constraint error, then have - -- a look at what check is being performed and ??? - - if Nkind (R_Cno) = N_Raise_Constraint_Error - and then Present (Condition (R_Cno)) - then - Cond := Condition (R_Cno); - - -- Case where node does not now have a dynamic check - - if not Has_Dynamic_Length_Check (Ck_Node) then - - -- If checks are on, just insert the check - - if Checks_On then - Insert_Action (Ck_Node, R_Cno); - - if not Do_Static then - Set_Has_Dynamic_Length_Check (Ck_Node); - end if; - - -- If checks are off, then analyze the length check after - -- temporarily attaching it to the tree in case the relevant - -- condition can be evaluated at compile time. We still want a - -- compile time warning in this case. - - else - Set_Parent (R_Cno, Ck_Node); - Analyze (R_Cno); - end if; - end if; - - -- Output a warning if the condition is known to be True - - if Is_Entity_Name (Cond) - and then Entity (Cond) = Standard_True - then - Apply_Compile_Time_Constraint_Error - (Ck_Node, "wrong length for array of}??", - CE_Length_Check_Failed, - Ent => Target_Typ, - Typ => Target_Typ); - - -- If we were only doing a static check, or if checks are not - -- on, then we want to delete the check, since it is not needed. - -- We do this by replacing the if statement by a null statement - - elsif Do_Static or else not Checks_On then - Remove_Warning_Messages (R_Cno); - Rewrite (R_Cno, Make_Null_Statement (Loc)); - end if; - - else - Install_Static_Check (R_Cno, Loc); - end if; - end loop; - end Apply_Selected_Length_Checks; - - --------------------------------- - -- Apply_Selected_Range_Checks -- - --------------------------------- - - procedure Apply_Selected_Range_Checks - (Ck_Node : Node_Id; - Target_Typ : Entity_Id; - Source_Typ : Entity_Id; - Do_Static : Boolean) - is - Cond : Node_Id; - R_Result : Check_Result; - R_Cno : Node_Id; - - Loc : constant Source_Ptr := Sloc (Ck_Node); - Checks_On : constant Boolean := - (not Index_Checks_Suppressed (Target_Typ)) - or else (not Range_Checks_Suppressed (Target_Typ)); - - begin - if not Full_Expander_Active or else not Checks_On then - return; - end if; - - R_Result := - Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty); - - for J in 1 .. 2 loop - - R_Cno := R_Result (J); - exit when No (R_Cno); - - -- If the item is a conditional raise of constraint error, then have - -- a look at what check is being performed and ??? - - if Nkind (R_Cno) = N_Raise_Constraint_Error - and then Present (Condition (R_Cno)) - then - Cond := Condition (R_Cno); - - if not Has_Dynamic_Range_Check (Ck_Node) then - Insert_Action (Ck_Node, R_Cno); - - if not Do_Static then - Set_Has_Dynamic_Range_Check (Ck_Node); - end if; - end if; - - -- Output a warning if the condition is known to be True - - if Is_Entity_Name (Cond) - and then Entity (Cond) = Standard_True - then - -- Since an N_Range is technically not an expression, we have - -- to set one of the bounds to C_E and then just flag the - -- N_Range. The warning message will point to the lower bound - -- and complain about a range, which seems OK. - - if Nkind (Ck_Node) = N_Range then - Apply_Compile_Time_Constraint_Error - (Low_Bound (Ck_Node), "static range out of bounds of}??", - CE_Range_Check_Failed, - Ent => Target_Typ, - Typ => Target_Typ); - - Set_Raises_Constraint_Error (Ck_Node); - - else - Apply_Compile_Time_Constraint_Error - (Ck_Node, "static value out of range of}?", - CE_Range_Check_Failed, - Ent => Target_Typ, - Typ => Target_Typ); - end if; - - -- If we were only doing a static check, or if checks are not - -- on, then we want to delete the check, since it is not needed. - -- We do this by replacing the if statement by a null statement - - elsif Do_Static or else not Checks_On then - Remove_Warning_Messages (R_Cno); - Rewrite (R_Cno, Make_Null_Statement (Loc)); - end if; - - else - Install_Static_Check (R_Cno, Loc); - end if; - end loop; - end Apply_Selected_Range_Checks; - - ------------------------------- - -- Apply_Static_Length_Check -- - ------------------------------- - - procedure Apply_Static_Length_Check - (Expr : Node_Id; - Target_Typ : Entity_Id; - Source_Typ : Entity_Id := Empty) - is - begin - Apply_Selected_Length_Checks - (Expr, Target_Typ, Source_Typ, Do_Static => True); - end Apply_Static_Length_Check; - - ------------------------------------- - -- Apply_Subscript_Validity_Checks -- - ------------------------------------- - - procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is - Sub : Node_Id; - - begin - pragma Assert (Nkind (Expr) = N_Indexed_Component); - - -- Loop through subscripts - - Sub := First (Expressions (Expr)); - while Present (Sub) loop - - -- Check one subscript. Note that we do not worry about enumeration - -- type with holes, since we will convert the value to a Pos value - -- for the subscript, and that convert will do the necessary validity - -- check. - - Ensure_Valid (Sub, Holes_OK => True); - - -- Move to next subscript - - Sub := Next (Sub); - end loop; - end Apply_Subscript_Validity_Checks; - - ---------------------------------- - -- Apply_Type_Conversion_Checks -- - ---------------------------------- - - procedure Apply_Type_Conversion_Checks (N : Node_Id) is - Target_Type : constant Entity_Id := Etype (N); - Target_Base : constant Entity_Id := Base_Type (Target_Type); - Expr : constant Node_Id := Expression (N); - - Expr_Type : constant Entity_Id := Underlying_Type (Etype (Expr)); - -- Note: if Etype (Expr) is a private type without discriminants, its - -- full view might have discriminants with defaults, so we need the - -- full view here to retrieve the constraints. - - begin - if Inside_A_Generic then - return; - - -- Skip these checks if serious errors detected, there are some nasty - -- situations of incomplete trees that blow things up. - - elsif Serious_Errors_Detected > 0 then - return; - - -- Scalar type conversions of the form Target_Type (Expr) require a - -- range check if we cannot be sure that Expr is in the base type of - -- Target_Typ and also that Expr is in the range of Target_Typ. These - -- are not quite the same condition from an implementation point of - -- view, but clearly the second includes the first. - - elsif Is_Scalar_Type (Target_Type) then - declare - Conv_OK : constant Boolean := Conversion_OK (N); - -- If the Conversion_OK flag on the type conversion is set and no - -- floating point type is involved in the type conversion then - -- fixed point values must be read as integral values. - - Float_To_Int : constant Boolean := - Is_Floating_Point_Type (Expr_Type) - and then Is_Integer_Type (Target_Type); - - begin - if not Overflow_Checks_Suppressed (Target_Base) - and then not 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, conversions are applied during expansion, to take into - -- accounts changes of representation. The checks become range checks on - -- the base type or length checks on the subtype, depending on whether - -- the target type is unconstrained or constrained. - - else - null; - end if; - end Apply_Type_Conversion_Checks; - - ---------------------------------------------- - -- Apply_Universal_Integer_Attribute_Checks -- - ---------------------------------------------- - - procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Typ : constant Entity_Id := Etype (N); - - begin - if Inside_A_Generic then - return; - - -- Nothing to do if checks are suppressed - - elsif Range_Checks_Suppressed (Typ) - and then Overflow_Checks_Suppressed (Typ) - then - return; - - -- Nothing to do if the attribute does not come from source. The - -- internal attributes we generate of this type do not need checks, - -- and furthermore the attempt to check them causes some circular - -- elaboration orders when dealing with packed types. - - elsif not Comes_From_Source (N) then - return; - - -- If the prefix is a selected component that depends on a discriminant - -- the check may improperly expose a discriminant instead of using - -- the bounds of the object itself. Set the type of the attribute to - -- the base type of the context, so that a check will be imposed when - -- needed (e.g. if the node appears as an index). - - elsif Nkind (Prefix (N)) = N_Selected_Component - and then Ekind (Typ) = E_Signed_Integer_Subtype - and then Depends_On_Discriminant (Scalar_Range (Typ)) - then - Set_Etype (N, Base_Type (Typ)); - - -- Otherwise, replace the attribute node with a type conversion node - -- whose expression is the attribute, retyped to universal integer, and - -- whose subtype mark is the target type. The call to analyze this - -- conversion will set range and overflow checks as required for proper - -- detection of an out of range value. - - else - Set_Etype (N, Universal_Integer); - Set_Analyzed (N, True); - - Rewrite (N, - Make_Type_Conversion (Loc, - Subtype_Mark => New_Occurrence_Of (Typ, Loc), - Expression => Relocate_Node (N))); - - Analyze_And_Resolve (N, Typ); - return; - end if; - end Apply_Universal_Integer_Attribute_Checks; - - ------------------------------------- - -- Atomic_Synchronization_Disabled -- - ------------------------------------- - - -- Note: internally Disable/Enable_Atomic_Synchronization is implemented - -- using a bogus check called Atomic_Synchronization. This is to make it - -- more convenient to get exactly the same semantics as [Un]Suppress. - - function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is - begin - -- If debug flag d.e is set, always return False, i.e. all atomic sync - -- looks enabled, since it is never disabled. - - if Debug_Flag_Dot_E then - return False; - - -- If debug flag d.d is set then always return True, i.e. all atomic - -- sync looks disabled, since it always tests True. - - elsif Debug_Flag_Dot_D then - return True; - - -- If entity present, then check result for that entity - - elsif Present (E) and then Checks_May_Be_Suppressed (E) then - return Is_Check_Suppressed (E, Atomic_Synchronization); - - -- Otherwise result depends on current scope setting - - else - return Scope_Suppress.Suppress (Atomic_Synchronization); - end if; - end Atomic_Synchronization_Disabled; - - ------------------------------- - -- Build_Discriminant_Checks -- - ------------------------------- - - function Build_Discriminant_Checks - (N : Node_Id; - T_Typ : Entity_Id) return Node_Id - is - Loc : constant Source_Ptr := Sloc (N); - Cond : Node_Id; - Disc : Elmt_Id; - Disc_Ent : Entity_Id; - Dref : Node_Id; - Dval : Node_Id; - - function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id; - - ---------------------------------- - -- Aggregate_Discriminant_Value -- - ---------------------------------- - - function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is - Assoc : Node_Id; - - begin - -- The aggregate has been normalized with named associations. We use - -- the Chars field to locate the discriminant to take into account - -- discriminants in derived types, which carry the same name as those - -- in the parent. - - Assoc := First (Component_Associations (N)); - while Present (Assoc) loop - if Chars (First (Choices (Assoc))) = Chars (Disc) then - return Expression (Assoc); - else - Next (Assoc); - end if; - end loop; - - -- Discriminant must have been found in the loop above - - raise Program_Error; - end Aggregate_Discriminant_Val; - - -- Start of processing for Build_Discriminant_Checks - - begin - -- Loop through discriminants evolving the condition - - Cond := Empty; - Disc := First_Elmt (Discriminant_Constraint (T_Typ)); - - -- For a fully private type, use the discriminants of the parent type - - if Is_Private_Type (T_Typ) - and then No (Full_View (T_Typ)) - then - Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ))); - else - Disc_Ent := First_Discriminant (T_Typ); - end if; - - while Present (Disc) loop - Dval := Node (Disc); - - if Nkind (Dval) = N_Identifier - and then Ekind (Entity (Dval)) = E_Discriminant - then - Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc); - else - Dval := Duplicate_Subexpr_No_Checks (Dval); - end if; - - -- If we have an Unchecked_Union node, we can infer the discriminants - -- of the node. - - if Is_Unchecked_Union (Base_Type (T_Typ)) then - Dref := New_Copy ( - Get_Discriminant_Value ( - First_Discriminant (T_Typ), - T_Typ, - Stored_Constraint (T_Typ))); - - elsif Nkind (N) = N_Aggregate then - Dref := - Duplicate_Subexpr_No_Checks - (Aggregate_Discriminant_Val (Disc_Ent)); - - else - Dref := - Make_Selected_Component (Loc, - Prefix => - Duplicate_Subexpr_No_Checks (N, Name_Req => True), - Selector_Name => - Make_Identifier (Loc, Chars (Disc_Ent))); - - Set_Is_In_Discriminant_Check (Dref); - end if; - - Evolve_Or_Else (Cond, - Make_Op_Ne (Loc, - Left_Opnd => Dref, - Right_Opnd => Dval)); - - Next_Elmt (Disc); - Next_Discriminant (Disc_Ent); - end loop; - - return Cond; - end Build_Discriminant_Checks; - - ------------------ - -- Check_Needed -- - ------------------ - - function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is - N : Node_Id; - P : Node_Id; - K : Node_Kind; - L : Node_Id; - R : Node_Id; - - begin - -- Always check if not simple entity - - if Nkind (Nod) not in N_Has_Entity - or else not Comes_From_Source (Nod) - then - return True; - end if; - - -- Look up tree for short circuit - - N := Nod; - loop - P := Parent (N); - K := Nkind (P); - - -- Done if out of subexpression (note that we allow generated stuff - -- such as itype declarations in this context, to keep the loop going - -- since we may well have generated such stuff in complex situations. - -- Also done if no parent (probably an error condition, but no point - -- in behaving nasty if we find it!) - - if No (P) - or else (K not in N_Subexpr and then Comes_From_Source (P)) - then - return True; - - -- Or/Or Else case, where test is part of the right operand, or is - -- part of one of the actions associated with the right operand, and - -- the left operand is an equality test. - - elsif K = N_Op_Or then - exit when N = Right_Opnd (P) - and then Nkind (Left_Opnd (P)) = N_Op_Eq; - - elsif K = N_Or_Else then - exit when (N = Right_Opnd (P) - or else - (Is_List_Member (N) - and then List_Containing (N) = Actions (P))) - and then Nkind (Left_Opnd (P)) = N_Op_Eq; - - -- Similar test for the And/And then case, where the left operand - -- is an inequality test. - - elsif K = N_Op_And then - exit when N = Right_Opnd (P) - and then Nkind (Left_Opnd (P)) = N_Op_Ne; - - elsif K = N_And_Then then - exit when (N = Right_Opnd (P) - or else - (Is_List_Member (N) - and then List_Containing (N) = Actions (P))) - and then Nkind (Left_Opnd (P)) = N_Op_Ne; - end if; - - N := P; - end loop; - - -- If we fall through the loop, then we have a conditional with an - -- appropriate test as its left operand. So test further. - - L := Left_Opnd (P); - R := Right_Opnd (L); - L := Left_Opnd (L); - - -- Left operand of test must match original variable - - if Nkind (L) not in N_Has_Entity - or else Entity (L) /= Entity (Nod) - then - return True; - end if; - - -- Right operand of test must be key value (zero or null) - - case Check is - when Access_Check => - if not Known_Null (R) then - return True; - end if; - - when Division_Check => - if not Compile_Time_Known_Value (R) - or else Expr_Value (R) /= Uint_0 - then - return True; - end if; - - when others => - raise Program_Error; - end case; - - -- Here we have the optimizable case, warn if not short-circuited - - if K = N_Op_And or else K = N_Op_Or then - case Check is - when Access_Check => - Error_Msg_N - ("Constraint_Error may be raised (access check)??", - Parent (Nod)); - when Division_Check => - Error_Msg_N - ("Constraint_Error may be raised (zero divide)??", - Parent (Nod)); - - when others => - raise Program_Error; - end case; - - if K = N_Op_And then - Error_Msg_N -- CODEFIX - ("use `AND THEN` instead of AND??", P); - else - Error_Msg_N -- CODEFIX - ("use `OR ELSE` instead of OR??", P); - end if; - - -- If not short-circuited, we need the check - - return True; - - -- If short-circuited, we can omit the check - - else - return False; - end if; - end Check_Needed; - - ----------------------------------- - -- Check_Valid_Lvalue_Subscripts -- - ----------------------------------- - - procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is - begin - -- Skip this if range checks are suppressed - - if Range_Checks_Suppressed (Etype (Expr)) then - return; - - -- Only do this check for expressions that come from source. We assume - -- that expander generated assignments explicitly include any necessary - -- checks. Note that this is not just an optimization, it avoids - -- infinite recursions! - - elsif not Comes_From_Source (Expr) then - return; - - -- For a selected component, check the prefix - - elsif Nkind (Expr) = N_Selected_Component then - Check_Valid_Lvalue_Subscripts (Prefix (Expr)); - return; - - -- Case of indexed component - - elsif Nkind (Expr) = N_Indexed_Component then - Apply_Subscript_Validity_Checks (Expr); - - -- Prefix may itself be or contain an indexed component, and these - -- subscripts need checking as well. - - Check_Valid_Lvalue_Subscripts (Prefix (Expr)); - end if; - end Check_Valid_Lvalue_Subscripts; - - ---------------------------------- - -- Null_Exclusion_Static_Checks -- - ---------------------------------- - - procedure Null_Exclusion_Static_Checks (N : Node_Id) is - Error_Node : Node_Id; - Expr : Node_Id; - Has_Null : constant Boolean := Has_Null_Exclusion (N); - K : constant Node_Kind := Nkind (N); - Typ : Entity_Id; - - begin - pragma Assert - (K = N_Component_Declaration - or else K = N_Discriminant_Specification - or else K = N_Function_Specification - or else K = N_Object_Declaration - or else K = N_Parameter_Specification); - - if K = N_Function_Specification then - Typ := Etype (Defining_Entity (N)); - else - Typ := Etype (Defining_Identifier (N)); - end if; - - case K is - when N_Component_Declaration => - if Present (Access_Definition (Component_Definition (N))) then - Error_Node := Component_Definition (N); - else - Error_Node := Subtype_Indication (Component_Definition (N)); - end if; - - when N_Discriminant_Specification => - Error_Node := Discriminant_Type (N); - - when N_Function_Specification => - Error_Node := Result_Definition (N); - - when N_Object_Declaration => - Error_Node := Object_Definition (N); - - when N_Parameter_Specification => - Error_Node := Parameter_Type (N); - - when others => - raise Program_Error; - end case; - - if Has_Null then - - -- Enforce legality rule 3.10 (13): A null exclusion can only be - -- applied to an access [sub]type. - - if not Is_Access_Type (Typ) then - Error_Msg_N - ("`NOT NULL` allowed only for an access type", Error_Node); - - -- Enforce legality rule RM 3.10(14/1): A null exclusion can only - -- be applied to a [sub]type that does not exclude null already. - - elsif Can_Never_Be_Null (Typ) - and then Comes_From_Source (Typ) - then - Error_Msg_NE - ("`NOT NULL` not allowed (& already excludes null)", - Error_Node, Typ); - end if; - end if; - - -- Check that null-excluding objects are always initialized, except for - -- deferred constants, for which the expression will appear in the full - -- declaration. - - if K = N_Object_Declaration - and then No (Expression (N)) - and then not Constant_Present (N) - and then not No_Initialization (N) - then - -- Add an expression that assigns null. This node is needed by - -- Apply_Compile_Time_Constraint_Error, which will replace this with - -- a Constraint_Error node. - - Set_Expression (N, Make_Null (Sloc (N))); - Set_Etype (Expression (N), Etype (Defining_Identifier (N))); - - Apply_Compile_Time_Constraint_Error - (N => Expression (N), - Msg => - "(Ada 2005) null-excluding objects must be initialized??", - Reason => CE_Null_Not_Allowed); - end if; - - -- Check that a null-excluding component, formal or object is not being - -- assigned a null value. Otherwise generate a warning message and - -- replace Expression (N) by an N_Constraint_Error node. - - if K /= N_Function_Specification then - Expr := Expression (N); - - if Present (Expr) and then Known_Null (Expr) then - case K is - when N_Component_Declaration | - N_Discriminant_Specification => - Apply_Compile_Time_Constraint_Error - (N => Expr, - Msg => "(Ada 2005) null not allowed " & - "in null-excluding components??", - Reason => CE_Null_Not_Allowed); - - when N_Object_Declaration => - Apply_Compile_Time_Constraint_Error - (N => Expr, - Msg => "(Ada 2005) null not allowed " & - "in null-excluding objects?", - Reason => CE_Null_Not_Allowed); - - when N_Parameter_Specification => - Apply_Compile_Time_Constraint_Error - (N => Expr, - Msg => "(Ada 2005) null not allowed " & - "in null-excluding formals??", - Reason => CE_Null_Not_Allowed); - - when others => - null; - end case; - end if; - end if; - end Null_Exclusion_Static_Checks; - - ---------------------------------- - -- Conditional_Statements_Begin -- - ---------------------------------- - - procedure Conditional_Statements_Begin is - begin - Saved_Checks_TOS := Saved_Checks_TOS + 1; - - -- If stack overflows, kill all checks, that way we know to simply reset - -- the number of saved checks to zero on return. This should never occur - -- in practice. - - if Saved_Checks_TOS > Saved_Checks_Stack'Last then - Kill_All_Checks; - - -- In the normal case, we just make a new stack entry saving the current - -- number of saved checks for a later restore. - - else - Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks; - - if Debug_Flag_CC then - w ("Conditional_Statements_Begin: Num_Saved_Checks = ", - Num_Saved_Checks); - end if; - end if; - end Conditional_Statements_Begin; - - -------------------------------- - -- Conditional_Statements_End -- - -------------------------------- - - procedure Conditional_Statements_End is - begin - pragma Assert (Saved_Checks_TOS > 0); - - -- If the saved checks stack overflowed, then we killed all checks, so - -- setting the number of saved checks back to zero is correct. This - -- should never occur in practice. - - if Saved_Checks_TOS > Saved_Checks_Stack'Last then - Num_Saved_Checks := 0; - - -- In the normal case, restore the number of saved checks from the top - -- stack entry. - - else - Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS); - if Debug_Flag_CC then - w ("Conditional_Statements_End: Num_Saved_Checks = ", - Num_Saved_Checks); - end if; - end if; - - Saved_Checks_TOS := Saved_Checks_TOS - 1; - end Conditional_Statements_End; - - ------------------------- - -- 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; - - -- An annoying special case. If this is an out parameter of a scalar - -- type, then the value is not going to be accessed, therefore it is - -- inappropriate to do any validity check at the call site. - - else - -- Only need to worry about scalar types - - if Is_Scalar_Type (Typ) then - declare - P : Node_Id; - N : Node_Id; - E : Entity_Id; - F : Entity_Id; - A : Node_Id; - L : List_Id; - - begin - -- Find actual argument (which may be a parameter association) - -- and the parent of the actual argument (the call statement) - - N := Expr; - P := Parent (Expr); - - if Nkind (P) = N_Parameter_Association then - N := P; - P := Parent (N); - end if; - - -- Only need to worry if we are argument of a procedure call - -- since functions don't have out parameters. If this is an - -- indirect or dispatching call, get signature from the - -- subprogram type. - - if Nkind (P) = N_Procedure_Call_Statement then - L := Parameter_Associations (P); - - if Is_Entity_Name (Name (P)) then - E := Entity (Name (P)); - else - pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference); - E := Etype (Name (P)); - end if; - - -- Only need to worry if there are indeed actuals, and if - -- this could be a procedure call, otherwise we cannot get a - -- match (either we are not an argument, or the mode of the - -- formal is not OUT). This test also filters out the - -- generic case. - - if Is_Non_Empty_List (L) - and then Is_Subprogram (E) - then - -- This is the loop through parameters, looking for an - -- OUT parameter for which we are the argument. - - F := First_Formal (E); - A := First (L); - while Present (F) loop - if Ekind (F) = E_Out_Parameter and then A = N then - return; - end if; - - Next_Formal (F); - Next (A); - end loop; - end if; - end if; - end; - end if; - end if; - - -- If this is a boolean expression, only its elementary operands need - -- checking: if they are valid, a boolean or short-circuit operation - -- with them will be valid as well. - - if Base_Type (Typ) = Standard_Boolean - and then - (Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit) - then - return; - end if; - - -- If we fall through, a validity check is required - - Insert_Valid_Check (Expr); - - if Is_Entity_Name (Expr) - and then Safe_To_Capture_Value (Expr, Entity (Expr)) - then - Set_Is_Known_Valid (Entity (Expr)); - end if; - end Ensure_Valid; - - ---------------------- - -- Expr_Known_Valid -- - ---------------------- - - function Expr_Known_Valid (Expr : Node_Id) return Boolean is - Typ : constant Entity_Id := Etype (Expr); - - begin - -- Non-scalar types are always considered valid, since they never give - -- rise to the issues of erroneous or bounded error behavior that are - -- the concern. In formal reference manual terms the notion of validity - -- only applies to scalar types. Note that even when packed arrays are - -- represented using modular types, they are still arrays semantically, - -- so they are also always valid (in particular, the unused bits can be - -- random rubbish without affecting the validity of the array value). - - if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then - return True; - - -- If no validity checking, then everything is considered valid - - elsif not Validity_Checks_On then - return True; - - -- Floating-point types are considered valid unless floating-point - -- validity checks have been specifically turned on. - - elsif Is_Floating_Point_Type (Typ) - and then not Validity_Check_Floating_Point - then - return True; - - -- If the expression is the value of an object that is known to be - -- valid, then clearly the expression value itself is valid. - - elsif Is_Entity_Name (Expr) - and then Is_Known_Valid (Entity (Expr)) - then - return True; - - -- References to discriminants are always considered valid. The value - -- of a discriminant gets checked when the object is built. Within the - -- record, we consider it valid, and it is important to do so, since - -- otherwise we can try to generate bogus validity checks which - -- reference discriminants out of scope. Discriminants of concurrent - -- types are excluded for the same reason. - - elsif Is_Entity_Name (Expr) - and then Denotes_Discriminant (Expr, Check_Concurrent => True) - then - return True; - - -- If the type is one for which all values are known valid, then we are - -- sure that the value is valid except in the slightly odd case where - -- the expression is a reference to a variable whose size has been - -- explicitly set to a value greater than the object size. - - elsif Is_Known_Valid (Typ) then - if Is_Entity_Name (Expr) - and then Ekind (Entity (Expr)) = E_Variable - and then Esize (Entity (Expr)) > Esize (Typ) - then - return False; - else - return True; - end if; - - -- Integer and character literals always have valid values, where - -- appropriate these will be range checked in any case. - - elsif Nkind (Expr) = N_Integer_Literal - or else - Nkind (Expr) = N_Character_Literal - then - return True; - - -- 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 (Expr) = N_Type_Conversion - or else - Nkind (Expr) = N_Qualified_Expression - then - return Expr_Known_Valid (Expression (Expr)); - - -- The result of any operator is always considered valid, since we - -- assume the necessary checks are done by the operator. For operators - -- on floating-point operations, we must also check when the operation - -- is the right-hand side of an assignment, or is an actual in a call. - - elsif Nkind (Expr) in N_Op then - if Is_Floating_Point_Type (Typ) - and then Validity_Check_Floating_Point - and then - (Nkind (Parent (Expr)) = N_Assignment_Statement - or else Nkind (Parent (Expr)) = N_Function_Call - or else Nkind (Parent (Expr)) = N_Parameter_Association) - then - return False; - else - return True; - end if; - - -- The result of a membership test is always valid, since it is true or - -- false, there are no other possibilities. - - elsif Nkind (Expr) in N_Membership_Test then - return True; - - -- For all other cases, we do not know the expression is valid - - else - return False; - end if; - end Expr_Known_Valid; - - ---------------- - -- Find_Check -- - ---------------- - - procedure Find_Check - (Expr : Node_Id; - Check_Type : Character; - Target_Type : Entity_Id; - Entry_OK : out Boolean; - Check_Num : out Nat; - Ent : out Entity_Id; - Ofs : out Uint) - is - function Within_Range_Of - (Target_Type : Entity_Id; - Check_Type : Entity_Id) return Boolean; - -- Given a requirement for checking a range against Target_Type, and - -- and a range Check_Type against which a check has already been made, - -- determines if the check against check type is sufficient to ensure - -- that no check against Target_Type is required. - - --------------------- - -- Within_Range_Of -- - --------------------- - - function Within_Range_Of - (Target_Type : Entity_Id; - Check_Type : Entity_Id) return Boolean - is - begin - if Target_Type = Check_Type then - return True; - - else - declare - Tlo : constant Node_Id := Type_Low_Bound (Target_Type); - Thi : constant Node_Id := Type_High_Bound (Target_Type); - Clo : constant Node_Id := Type_Low_Bound (Check_Type); - Chi : constant Node_Id := Type_High_Bound (Check_Type); - - begin - if (Tlo = Clo - or else (Compile_Time_Known_Value (Tlo) - and then - Compile_Time_Known_Value (Clo) - and then - Expr_Value (Clo) >= Expr_Value (Tlo))) - and then - (Thi = Chi - or else (Compile_Time_Known_Value (Thi) - and then - Compile_Time_Known_Value (Chi) - and then - Expr_Value (Chi) <= Expr_Value (Clo))) - then - return True; - else - return False; - end if; - end; - end if; - end Within_Range_Of; - - -- Start of processing for Find_Check - - begin - -- Establish default, in case no entry is found - - Check_Num := 0; - - -- Case of expression is simple entity reference - - if Is_Entity_Name (Expr) then - Ent := Entity (Expr); - Ofs := Uint_0; - - -- Case of expression is entity + known constant - - elsif Nkind (Expr) = N_Op_Add - and then Compile_Time_Known_Value (Right_Opnd (Expr)) - and then Is_Entity_Name (Left_Opnd (Expr)) - then - Ent := Entity (Left_Opnd (Expr)); - Ofs := Expr_Value (Right_Opnd (Expr)); - - -- Case of expression is entity - known constant - - elsif Nkind (Expr) = N_Op_Subtract - and then Compile_Time_Known_Value (Right_Opnd (Expr)) - and then Is_Entity_Name (Left_Opnd (Expr)) - then - Ent := Entity (Left_Opnd (Expr)); - Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr))); - - -- Any other expression is not of the right form - - else - Ent := Empty; - Ofs := Uint_0; - Entry_OK := False; - return; - end if; - - -- Come here with expression of appropriate form, check if entity is an - -- appropriate one for our purposes. - - if (Ekind (Ent) = E_Variable - or else Is_Constant_Object (Ent)) - and then not Is_Library_Level_Entity (Ent) - then - Entry_OK := True; - else - Entry_OK := False; - return; - end if; - - -- See if there is matching check already - - for J in reverse 1 .. Num_Saved_Checks loop - declare - SC : Saved_Check renames Saved_Checks (J); - - begin - if SC.Killed = False - and then SC.Entity = Ent - and then SC.Offset = Ofs - and then SC.Check_Type = Check_Type - and then Within_Range_Of (Target_Type, SC.Target_Type) - then - Check_Num := J; - return; - end if; - end; - end loop; - - -- If we fall through entry was not found - - return; - end Find_Check; - - --------------------------------- - -- Generate_Discriminant_Check -- - --------------------------------- - - -- Note: the code for this procedure is derived from the - -- Emit_Discriminant_Check Routine in trans.c. - - procedure Generate_Discriminant_Check (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Pref : constant Node_Id := Prefix (N); - Sel : constant Node_Id := Selector_Name (N); - - Orig_Comp : constant Entity_Id := - Original_Record_Component (Entity (Sel)); - -- The original component to be checked - - Discr_Fct : constant Entity_Id := - Discriminant_Checking_Func (Orig_Comp); - -- The discriminant checking function - - Discr : Entity_Id; - -- One discriminant to be checked in the type - - Real_Discr : Entity_Id; - -- Actual discriminant in the call - - Pref_Type : Entity_Id; - -- Type of relevant prefix (ignoring private/access stuff) - - Args : List_Id; - -- List of arguments for function call - - Formal : Entity_Id; - -- Keep track of the formal corresponding to the actual we build for - -- each discriminant, in order to be able to perform the necessary type - -- conversions. - - Scomp : Node_Id; - -- Selected component reference for checking function argument - - begin - Pref_Type := Etype (Pref); - - -- Force evaluation of the prefix, so that it does not get evaluated - -- twice (once for the check, once for the actual reference). Such a - -- double evaluation is always a potential source of inefficiency, - -- and is functionally incorrect in the volatile case, or when the - -- prefix may have side-effects. An entity or a component of an - -- entity requires no evaluation. - - if Is_Entity_Name (Pref) then - if Treat_As_Volatile (Entity (Pref)) then - Force_Evaluation (Pref, Name_Req => True); - end if; - - elsif Treat_As_Volatile (Etype (Pref)) then - Force_Evaluation (Pref, Name_Req => True); - - elsif Nkind (Pref) = N_Selected_Component - and then Is_Entity_Name (Prefix (Pref)) - then - null; - - else - Force_Evaluation (Pref, Name_Req => True); - end if; - - -- For a tagged type, use the scope of the original component to - -- obtain the type, because ??? - - if Is_Tagged_Type (Scope (Orig_Comp)) then - Pref_Type := Scope (Orig_Comp); - - -- For an untagged derived type, use the discriminants of the parent - -- which have been renamed in the derivation, possibly by a one-to-many - -- discriminant constraint. For non-tagged type, initially get the Etype - -- of the prefix - - else - if Is_Derived_Type (Pref_Type) - and then Number_Discriminants (Pref_Type) /= - Number_Discriminants (Etype (Base_Type (Pref_Type))) - then - Pref_Type := Etype (Base_Type (Pref_Type)); - end if; - end if; - - -- We definitely should have a checking function, This routine should - -- not be called if no discriminant checking function is present. - - pragma Assert (Present (Discr_Fct)); - - -- Create the list of the actual parameters for the call. This list - -- is the list of the discriminant fields of the record expression to - -- be discriminant checked. - - Args := New_List; - Formal := First_Formal (Discr_Fct); - Discr := First_Discriminant (Pref_Type); - while Present (Discr) loop - - -- If we have a corresponding discriminant field, and a parent - -- subtype is present, then we want to use the corresponding - -- discriminant since this is the one with the useful value. - - if Present (Corresponding_Discriminant (Discr)) - and then Ekind (Pref_Type) = E_Record_Type - and then Present (Parent_Subtype (Pref_Type)) - then - Real_Discr := Corresponding_Discriminant (Discr); - else - Real_Discr := Discr; - end if; - - -- Construct the reference to the discriminant - - Scomp := - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To (Pref_Type, - Duplicate_Subexpr (Pref)), - Selector_Name => New_Occurrence_Of (Real_Discr, Loc)); - - -- Manually analyze and resolve this selected component. We really - -- want it just as it appears above, and do not want the expander - -- playing discriminal games etc with this reference. Then we append - -- the argument to the list we are gathering. - - Set_Etype (Scomp, Etype (Real_Discr)); - Set_Analyzed (Scomp, True); - Append_To (Args, Convert_To (Etype (Formal), Scomp)); - - Next_Formal_With_Extras (Formal); - Next_Discriminant (Discr); - end loop; - - -- Now build and insert the call - - Insert_Action (N, - Make_Raise_Constraint_Error (Loc, - Condition => - Make_Function_Call (Loc, - Name => New_Occurrence_Of (Discr_Fct, Loc), - Parameter_Associations => Args), - Reason => CE_Discriminant_Check_Failed)); - end Generate_Discriminant_Check; - - --------------------------- - -- Generate_Index_Checks -- - --------------------------- - - procedure Generate_Index_Checks (N : Node_Id) is - - function Entity_Of_Prefix return Entity_Id; - -- Returns the entity of the prefix of N (or Empty if not found) - - ---------------------- - -- Entity_Of_Prefix -- - ---------------------- - - function Entity_Of_Prefix return Entity_Id is - P : Node_Id; - - begin - P := Prefix (N); - while not Is_Entity_Name (P) loop - if not Nkind_In (P, N_Selected_Component, - N_Indexed_Component) - then - return Empty; - end if; - - P := Prefix (P); - end loop; - - return Entity (P); - end Entity_Of_Prefix; - - -- Local variables - - Loc : constant Source_Ptr := Sloc (N); - A : constant Node_Id := Prefix (N); - A_Ent : constant Entity_Id := Entity_Of_Prefix; - Sub : Node_Id; - - -- Start of processing for Generate_Index_Checks - - begin - -- Ignore call if the prefix is not an array since we have a serious - -- error in the sources. Ignore it also if index checks are suppressed - -- for array object or type. - - if not Is_Array_Type (Etype (A)) - or else (Present (A_Ent) - and then Index_Checks_Suppressed (A_Ent)) - or else Index_Checks_Suppressed (Etype (A)) - then - return; - - -- 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_Reference_To (Etype (A), Loc), - Attribute_Name => Name_Range)), - Reason => CE_Index_Check_Failed)); - end if; - - -- General case - - else - declare - A_Idx : Node_Id := Empty; - A_Range : Node_Id; - Ind : Nat; - Num : List_Id; - Range_N : Node_Id; - - begin - A_Idx := First_Index (Etype (A)); - Ind := 1; - while Present (Sub) loop - if Do_Range_Check (Sub) then - Set_Do_Range_Check (Sub, False); - - -- Force evaluation except for the case of a simple name of - -- a non-volatile entity. - - if not Is_Entity_Name (Sub) - or else Treat_As_Volatile (Entity (Sub)) - then - Force_Evaluation (Sub); - end if; - - if Nkind (A_Idx) = N_Range then - A_Range := A_Idx; - - elsif Nkind (A_Idx) = N_Identifier - or else Nkind (A_Idx) = N_Expanded_Name - then - A_Range := Scalar_Range (Entity (A_Idx)); - - else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication); - A_Range := Range_Expression (Constraint (A_Idx)); - end if; - - -- For array objects with constant bounds we can generate - -- the index check using the bounds of the type of the index - - if Present (A_Ent) - and then Ekind (A_Ent) = E_Variable - and then Is_Constant_Bound (Low_Bound (A_Range)) - and then Is_Constant_Bound (High_Bound (A_Range)) - then - Range_N := - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To (Etype (A_Idx), Loc), - Attribute_Name => Name_Range); - - -- For arrays with non-constant bounds we cannot generate - -- the index check using the bounds of the type of the index - -- since it may reference discriminants of some enclosing - -- type. We obtain the bounds directly from the prefix - -- object. - - else - if Ind = 1 then - Num := No_List; - else - Num := New_List (Make_Integer_Literal (Loc, Ind)); - end if; - - Range_N := - Make_Attribute_Reference (Loc, - Prefix => - Duplicate_Subexpr_Move_Checks (A, Name_Req => True), - Attribute_Name => Name_Range, - Expressions => Num); - end if; - - Insert_Action (N, - Make_Raise_Constraint_Error (Loc, - Condition => - Make_Not_In (Loc, - Left_Opnd => - Convert_To (Base_Type (Etype (Sub)), - Duplicate_Subexpr_Move_Checks (Sub)), - Right_Opnd => Range_N), - Reason => CE_Index_Check_Failed)); - end if; - - A_Idx := Next_Index (A_Idx); - Ind := Ind + 1; - Next (Sub); - end loop; - end; - end if; - end Generate_Index_Checks; - - -------------------------- - -- Generate_Range_Check -- - -------------------------- - - procedure Generate_Range_Check - (N : Node_Id; - Target_Type : Entity_Id; - Reason : RT_Exception_Code) - is - Loc : constant Source_Ptr := Sloc (N); - Source_Type : constant Entity_Id := Etype (N); - Source_Base_Type : constant Entity_Id := Base_Type (Source_Type); - Target_Base_Type : constant Entity_Id := Base_Type (Target_Type); - - begin - -- First special case, if the source type is already within the range - -- of the target type, then no check is needed (probably we should have - -- stopped Do_Range_Check from being set in the first place, but better - -- late than 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 Full_Expander_Active or else not Checks_On then - return; - end if; - - if Static_Sloc = No_Location then - Internal_Static_Sloc := Sloc (Node); - end if; - - if No (Flag_Node) then - Internal_Flag_Node := Node; - end if; - - for J in 1 .. 2 loop - exit when No (Checks (J)); - - if Nkind (Checks (J)) = N_Raise_Constraint_Error - and then Present (Condition (Checks (J))) - then - if not Has_Dynamic_Range_Check (Internal_Flag_Node) then - Check_Node := Checks (J); - Mark_Rewrite_Insertion (Check_Node); - - if Do_Before then - Insert_Before_And_Analyze (Node, Check_Node); - else - Insert_After_And_Analyze (Node, Check_Node); - end if; - - Set_Has_Dynamic_Range_Check (Internal_Flag_Node); - end if; - - else - Check_Node := - Make_Raise_Constraint_Error (Internal_Static_Sloc, - Reason => CE_Range_Check_Failed); - Mark_Rewrite_Insertion (Check_Node); - - if Do_Before then - Insert_Before_And_Analyze (Node, Check_Node); - else - Insert_After_And_Analyze (Node, Check_Node); - end if; - end if; - end loop; - end Insert_Range_Checks; - - ------------------------ - -- Insert_Valid_Check -- - ------------------------ - - procedure Insert_Valid_Check (Expr : Node_Id) is - Loc : constant Source_Ptr := Sloc (Expr); - Exp : Node_Id; - - begin - -- Do not insert if checks off, or if not checking validity or - -- if expression is known to be valid - - if not Validity_Checks_On - or else Range_Or_Validity_Checks_Suppressed (Expr) - or else Expr_Known_Valid (Expr) - then - return; - end if; - - -- If we have a checked conversion, then validity check applies to - -- the expression inside the conversion, not the result, since if - -- the expression inside is valid, then so is the conversion result. - - Exp := Expr; - while Nkind (Exp) = N_Type_Conversion loop - Exp := Expression (Exp); - end loop; - - -- We are about to insert the validity check for Exp. We save and - -- reset the Do_Range_Check flag over this validity check, and then - -- put it back for the final original reference (Exp may be rewritten). - - declare - DRC : constant Boolean := Do_Range_Check (Exp); - 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 we are in a case expression, and not part of the - -- expression, then we 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, we find that N - -- belongs to a statement, thus it may never appear in - -- a declarative region. - - if Nkind (P) in N_Statement_Other_Than_Procedure_Call - or else Nkind (P) = N_Procedure_Call_Statement - then - return False; - end if; - - -- If we are at a declaration, record it and exit - - if Nkind (P) in N_Declaration - and then Nkind (P) not in N_Subprogram_Specification - then - N_Decl := P; - exit; - end if; - - P := Parent (P); - end loop; - - if No (N_Decl) then - return False; - end if; - - return List_Containing (N_Decl) = Declarations (S_Par); - end; - end Safe_To_Capture_In_Parameter_Value; - - ------------------- - -- Mark_Non_Null -- - ------------------- - - procedure Mark_Non_Null is - begin - -- Only case of interest is if node N is an entity name - - if Is_Entity_Name (N) then - - -- For sure, we want to clear an indication that this is known to - -- be null, since if we get past this check, it definitely is not! - - Set_Is_Known_Null (Entity (N), False); - - -- We can mark the entity as known to be non-null if either it is - -- safe to capture the value, or in the case of an IN parameter, - -- which is a constant, if the check we just installed is in the - -- declarative region of the subprogram body. In this latter case, - -- a check is decisive for the rest of the body if the expression - -- is sure to be elaborated, since we know we have to elaborate - -- all declarations before executing the body. - - -- Couldn't this always be part of Safe_To_Capture_Value ??? - - if Safe_To_Capture_Value (N, Entity (N)) - or else Safe_To_Capture_In_Parameter_Value - then - Set_Is_Known_Non_Null (Entity (N)); - end if; - end if; - end Mark_Non_Null; - - -- Start of processing for Install_Null_Excluding_Check - - begin - pragma Assert (Is_Access_Type (Typ)); - - -- No check inside a generic (why not???) - - if Inside_A_Generic then - return; - end if; - - -- No check needed if known to be non-null - - if Known_Non_Null (N) then - return; - end if; - - -- If known to be null, here is where we generate a compile time check - - if Known_Null (N) then - - -- Avoid generating warning message inside init procs - - if not Inside_Init_Proc then - Apply_Compile_Time_Constraint_Error - (N, - "null value not allowed here??", - CE_Access_Check_Failed); - else - Insert_Action (N, - Make_Raise_Constraint_Error (Loc, - Reason => CE_Access_Check_Failed)); - end if; - - Mark_Non_Null; - return; - end if; - - -- If entity is never assigned, for sure a warning is appropriate - - if Is_Entity_Name (N) then - Check_Unset_Reference (N); - end if; - - -- No check needed if checks are suppressed on the range. Note that we - -- don't set Is_Known_Non_Null in this case (we could legitimately do - -- so, since the program is erroneous, but we don't like to casually - -- propagate such conclusions from erroneosity). - - if Access_Checks_Suppressed (Typ) then - return; - end if; - - -- No check needed for access to concurrent record types generated by - -- the expander. This is not just an optimization (though it does indeed - -- remove junk checks). It also avoids generation of junk warnings. - - if Nkind (N) in N_Has_Chars - and then Chars (N) = Name_uObject - and then Is_Concurrent_Record_Type - (Directly_Designated_Type (Etype (N))) - then - return; - end if; - - -- No check needed for the Get_Current_Excep.all.all idiom generated by - -- the expander within exception handlers, since we know that the value - -- can never be null. - - -- Is this really the right way to do this? Normally we generate such - -- code in the expander with checks off, and that's how we suppress this - -- kind of junk check ??? - - if Nkind (N) = N_Function_Call - and then Nkind (Name (N)) = N_Explicit_Dereference - and then Nkind (Prefix (Name (N))) = N_Identifier - and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep) - then - return; - end if; - - -- Otherwise install access check - - Insert_Action (N, - Make_Raise_Constraint_Error (Loc, - Condition => - Make_Op_Eq (Loc, - Left_Opnd => Duplicate_Subexpr_Move_Checks (N), - Right_Opnd => Make_Null (Loc)), - Reason => CE_Access_Check_Failed)); - - Mark_Non_Null; - end Install_Null_Excluding_Check; - - -------------------------- - -- Install_Static_Check -- - -------------------------- - - procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is - Stat : constant Boolean := Is_Static_Expression (R_Cno); - Typ : constant Entity_Id := Etype (R_Cno); - - begin - Rewrite (R_Cno, - Make_Raise_Constraint_Error (Loc, - Reason => CE_Range_Check_Failed)); - Set_Analyzed (R_Cno); - Set_Etype (R_Cno, Typ); - Set_Raises_Constraint_Error (R_Cno); - Set_Is_Static_Expression (R_Cno, Stat); - - -- Now deal with possible local raise handling - - Possible_Local_Raise (R_Cno, Standard_Constraint_Error); - end Install_Static_Check; - - ------------------------- - -- 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_Reference_To (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_Reference_To (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; - - ----------------------------- - -- 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 2 checks ??? - - if Num_Checks = 2 then - return; - end if; - - pragma Assert (Num_Checks <= 1); - Num_Checks := Num_Checks + 1; - Ret_Result (Num_Checks) := N; - end if; - end Add_Check; - - ------------------ - -- Get_E_Length -- - ------------------ - - function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is - SE : constant Entity_Id := Scope (E); - N : Node_Id; - E1 : Entity_Id := E; - - begin - if Ekind (Scope (E)) = E_Record_Type - and then Has_Discriminants (Scope (E)) - then - N := Build_Discriminal_Subtype_Of_Component (E); - - if Present (N) then - Insert_Action (Ck_Node, N); - E1 := Defining_Identifier (N); - end if; - end if; - - if Ekind (E1) = E_String_Literal_Subtype then - return - Make_Integer_Literal (Loc, - Intval => String_Literal_Length (E1)); - - elsif SE /= Standard_Standard - and then Ekind (Scope (SE)) = E_Protected_Type - and then Has_Discriminants (Scope (SE)) - and then Has_Completion (Scope (SE)) - and then not Inside_Init_Proc - then - -- If the type whose length is needed is a private component - -- constrained by a discriminant, we must expand the 'Length - -- attribute into an explicit computation, using the discriminal - -- of the current protected operation. This is because the actual - -- type of the prival is constructed after the protected opera- - -- tion has been fully expanded. - - declare - Indx_Type : Node_Id; - Lo : Node_Id; - Hi : Node_Id; - Do_Expand : Boolean := False; - - begin - Indx_Type := First_Index (E); - - for J in 1 .. Indx - 1 loop - Next_Index (Indx_Type); - end loop; - - Get_Index_Bounds (Indx_Type, Lo, Hi); - - if Nkind (Lo) = N_Identifier - and then Ekind (Entity (Lo)) = E_In_Parameter - then - Lo := Get_Discriminal (E, Lo); - Do_Expand := True; - end if; - - if Nkind (Hi) = N_Identifier - and then Ekind (Entity (Hi)) = E_In_Parameter - then - Hi := Get_Discriminal (E, Hi); - Do_Expand := True; - end if; - - if Do_Expand then - if not Is_Entity_Name (Lo) then - Lo := Duplicate_Subexpr_No_Checks (Lo); - end if; - - if not Is_Entity_Name (Hi) then - Lo := Duplicate_Subexpr_No_Checks (Hi); - end if; - - N := - Make_Op_Add (Loc, - Left_Opnd => - Make_Op_Subtract (Loc, - Left_Opnd => Hi, - Right_Opnd => Lo), - - Right_Opnd => Make_Integer_Literal (Loc, 1)); - return N; - - else - N := - Make_Attribute_Reference (Loc, - Attribute_Name => Name_Length, - Prefix => - New_Occurrence_Of (E1, Loc)); - - if Indx > 1 then - Set_Expressions (N, New_List ( - Make_Integer_Literal (Loc, Indx))); - end if; - - return N; - end if; - end; - - else - N := - Make_Attribute_Reference (Loc, - Attribute_Name => Name_Length, - Prefix => - New_Occurrence_Of (E1, Loc)); - - if Indx > 1 then - Set_Expressions (N, New_List ( - Make_Integer_Literal (Loc, Indx))); - end if; - - return N; - end if; - end Get_E_Length; - - ------------------ - -- Get_N_Length -- - ------------------ - - function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is - begin - return - Make_Attribute_Reference (Loc, - Attribute_Name => Name_Length, - Prefix => - Duplicate_Subexpr_No_Checks (N, Name_Req => True), - Expressions => New_List ( - Make_Integer_Literal (Loc, Indx))); - end Get_N_Length; - - ------------------- - -- Length_E_Cond -- - ------------------- - - function Length_E_Cond - (Exptyp : Entity_Id; - Typ : Entity_Id; - Indx : Nat) return Node_Id - is - begin - return - Make_Op_Ne (Loc, - Left_Opnd => Get_E_Length (Typ, Indx), - Right_Opnd => Get_E_Length (Exptyp, Indx)); - end Length_E_Cond; - - ------------------- - -- Length_N_Cond -- - ------------------- - - function Length_N_Cond - (Expr : Node_Id; - Typ : Entity_Id; - Indx : Nat) return Node_Id - is - begin - return - Make_Op_Ne (Loc, - Left_Opnd => Get_E_Length (Typ, Indx), - Right_Opnd => Get_N_Length (Expr, Indx)); - end Length_N_Cond; - - ----------------- - -- Same_Bounds -- - ----------------- - - function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is - begin - return - (Nkind (L) = N_Integer_Literal - and then Nkind (R) = N_Integer_Literal - and then Intval (L) = Intval (R)) - - or else - (Is_Entity_Name (L) - and then Ekind (Entity (L)) = E_Constant - and then ((Is_Entity_Name (R) - and then Entity (L) = Entity (R)) - or else - (Nkind (R) = N_Type_Conversion - and then Is_Entity_Name (Expression (R)) - and then Entity (L) = Entity (Expression (R))))) - - or else - (Is_Entity_Name (R) - and then Ekind (Entity (R)) = E_Constant - and then Nkind (L) = N_Type_Conversion - and then Is_Entity_Name (Expression (L)) - and then Entity (R) = Entity (Expression (L))) - - or else - (Is_Entity_Name (L) - and then Is_Entity_Name (R) - and then Entity (L) = Entity (R) - and then Ekind (Entity (L)) = E_In_Parameter - and then Inside_Init_Proc); - end Same_Bounds; - - -- Start of processing for Selected_Length_Checks - - begin - if not Full_Expander_Active then - return Ret_Result; - end if; - - if Target_Typ = Any_Type - or else Target_Typ = Any_Composite - or else Raises_Constraint_Error (Ck_Node) - then - return Ret_Result; - end if; - - if No (Wnode) then - Wnode := Ck_Node; - end if; - - T_Typ := Target_Typ; - - if No (Source_Typ) then - S_Typ := Etype (Ck_Node); - else - S_Typ := Source_Typ; - end if; - - if S_Typ = Any_Type or else S_Typ = Any_Composite then - return Ret_Result; - end if; - - if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then - S_Typ := Designated_Type (S_Typ); - T_Typ := Designated_Type (T_Typ); - Do_Access := True; - - -- A simple optimization for the null case - - if Known_Null (Ck_Node) then - return Ret_Result; - end if; - end if; - - if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then - if Is_Constrained (T_Typ) then - - -- The checking code to be generated will freeze the corresponding - -- array type. However, we must freeze the type now, so that the - -- freeze node does not appear within the generated 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 Full_Expander_Active then - return Ret_Result; - end if; - - if Target_Typ = Any_Type - or else Target_Typ = Any_Composite - or else Raises_Constraint_Error (Ck_Node) - then - return Ret_Result; - end if; - - if No (Wnode) then - Wnode := Ck_Node; - end if; - - T_Typ := Target_Typ; - - if No (Source_Typ) then - S_Typ := Etype (Ck_Node); - else - S_Typ := Source_Typ; - end if; - - if S_Typ = Any_Type or else S_Typ = Any_Composite then - return Ret_Result; - end if; - - -- The order of evaluating T_Typ before S_Typ seems to be critical - -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed - -- in, and since Node can be an N_Range node, it might be invalid. - -- Should there be an assert check somewhere for taking the Etype of - -- an N_Range node ??? - - if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then - S_Typ := Designated_Type (S_Typ); - T_Typ := Designated_Type (T_Typ); - Do_Access := True; - - -- A simple optimization for the null case - - if Known_Null (Ck_Node) then - return Ret_Result; - end if; - end if; - - -- For an N_Range Node, check for a null range and then if not - -- null generate a range check action. - - if Nkind (Ck_Node) = N_Range then - - -- There's no point in checking a range against itself - - if Ck_Node = Scalar_Range (T_Typ) then - return Ret_Result; - end if; - - declare - T_LB : constant Node_Id := Type_Low_Bound (T_Typ); - T_HB : constant Node_Id := Type_High_Bound (T_Typ); - Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB); - Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB); - - LB : Node_Id := Low_Bound (Ck_Node); - HB : Node_Id := High_Bound (Ck_Node); - Known_LB : Boolean; - Known_HB : Boolean; - - Null_Range : Boolean; - Out_Of_Range_L : Boolean; - Out_Of_Range_H : Boolean; - - begin - -- Compute what is known at compile time - - if Known_T_LB and Known_T_HB then - if Compile_Time_Known_Value (LB) then - Known_LB := True; - - -- There's no point in checking that a bound is within its - -- own range so pretend that it is known in this case. First - -- deal with low bound. - - elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype - and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ) - then - LB := T_LB; - Known_LB := True; - - else - Known_LB := False; - end if; - - -- Likewise for the high bound - - if Compile_Time_Known_Value (HB) then - Known_HB := True; - - elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype - and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ) - then - HB := T_HB; - Known_HB := True; - - else - Known_HB := False; - end if; - end if; - - -- Check for case where everything is static and we can do the - -- check at compile time. This is skipped if we have an access - -- type, since the access value may be null. - - -- ??? This code can be improved since you only need to know that - -- the two respective bounds (LB & T_LB or HB & T_HB) are known at - -- compile time to emit pertinent messages. - - if Known_T_LB and Known_T_HB and Known_LB and Known_HB - and not Do_Access - then - -- Floating-point case - - if Is_Floating_Point_Type (S_Typ) then - Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB); - Out_Of_Range_L := - (Expr_Value_R (LB) < Expr_Value_R (T_LB)) - or else - (Expr_Value_R (LB) > Expr_Value_R (T_HB)); - - Out_Of_Range_H := - (Expr_Value_R (HB) > Expr_Value_R (T_HB)) - or else - (Expr_Value_R (HB) < Expr_Value_R (T_LB)); - - -- Fixed or discrete type case - - else - Null_Range := Expr_Value (HB) < Expr_Value (LB); - Out_Of_Range_L := - (Expr_Value (LB) < Expr_Value (T_LB)) - or else - (Expr_Value (LB) > Expr_Value (T_HB)); - - Out_Of_Range_H := - (Expr_Value (HB) > Expr_Value (T_HB)) - or else - (Expr_Value (HB) < Expr_Value (T_LB)); - end if; - - if not Null_Range then - if Out_Of_Range_L then - if No (Warn_Node) then - Add_Check - (Compile_Time_Constraint_Error - (Low_Bound (Ck_Node), - "static value out of range of}??", T_Typ)); - - else - Add_Check - (Compile_Time_Constraint_Error - (Wnode, - "static range out of bounds of}??", T_Typ)); - end if; - end if; - - if Out_Of_Range_H then - if No (Warn_Node) then - Add_Check - (Compile_Time_Constraint_Error - (High_Bound (Ck_Node), - "static value out of range of}??", T_Typ)); - - else - Add_Check - (Compile_Time_Constraint_Error - (Wnode, - "static range out of bounds of}??", T_Typ)); - end if; - end if; - end if; - - else - declare - LB : Node_Id := Low_Bound (Ck_Node); - HB : Node_Id := High_Bound (Ck_Node); - - begin - -- If either bound is a discriminant and we are within the - -- record declaration, it is a use of the discriminant in a - -- constraint of a component, and nothing can be checked - -- here. The check will be emitted within the init proc. - -- Before then, the discriminal has no real meaning. - -- Similarly, if the entity is a discriminal, there is no - -- check to perform yet. - - -- The same holds within a discriminated synchronized type, - -- where the discriminant may constrain a component or an - -- entry family. - - if Nkind (LB) = N_Identifier - and then Denotes_Discriminant (LB, True) - then - if Current_Scope = Scope (Entity (LB)) - or else Is_Concurrent_Type (Current_Scope) - or else Ekind (Entity (LB)) /= E_Discriminant - then - return Ret_Result; - else - LB := - New_Occurrence_Of (Discriminal (Entity (LB)), Loc); - end if; - end if; - - if Nkind (HB) = N_Identifier - and then Denotes_Discriminant (HB, True) - then - if Current_Scope = Scope (Entity (HB)) - or else Is_Concurrent_Type (Current_Scope) - or else Ekind (Entity (HB)) /= E_Discriminant - then - return Ret_Result; - else - HB := - New_Occurrence_Of (Discriminal (Entity (HB)), Loc); - end if; - end if; - - Cond := Discrete_Range_Cond (Ck_Node, T_Typ); - Set_Paren_Count (Cond, 1); - - Cond := - Make_And_Then (Loc, - Left_Opnd => - Make_Op_Ge (Loc, - Left_Opnd => Duplicate_Subexpr_No_Checks (HB), - Right_Opnd => Duplicate_Subexpr_No_Checks (LB)), - Right_Opnd => Cond); - end; - end if; - end; - - elsif Is_Scalar_Type (S_Typ) then - - -- This somewhat duplicates what Apply_Scalar_Range_Check does, - -- except the above simply sets a flag in the node and lets - -- gigi generate the check base on the Etype of the expression. - -- Sometimes, however we want to do a dynamic check against an - -- arbitrary target type, so we do that here. - - if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then - Cond := Discrete_Expr_Cond (Ck_Node, T_Typ); - - -- For literals, we can tell if the constraint error will be - -- raised at compile time, so we never need a dynamic check, but - -- if the exception will be raised, then post the usual warning, - -- and replace the literal with a raise constraint error - -- expression. As usual, skip this for access types - - elsif Compile_Time_Known_Value (Ck_Node) - and then not Do_Access - then - declare - LB : constant Node_Id := Type_Low_Bound (T_Typ); - UB : constant Node_Id := Type_High_Bound (T_Typ); - - Out_Of_Range : Boolean; - Static_Bounds : constant Boolean := - Compile_Time_Known_Value (LB) - and Compile_Time_Known_Value (UB); - - begin - -- Following range tests should use Sem_Eval routine ??? - - if Static_Bounds then - if Is_Floating_Point_Type (S_Typ) then - Out_Of_Range := - (Expr_Value_R (Ck_Node) < Expr_Value_R (LB)) - or else - (Expr_Value_R (Ck_Node) > Expr_Value_R (UB)); - - -- Fixed or discrete type - - else - Out_Of_Range := - Expr_Value (Ck_Node) < Expr_Value (LB) - or else - Expr_Value (Ck_Node) > Expr_Value (UB); - end if; - - -- Bounds of the type are static and the literal is out of - -- range so output a warning message. - - if Out_Of_Range then - if No (Warn_Node) then - Add_Check - (Compile_Time_Constraint_Error - (Ck_Node, - "static value out of range of}??", T_Typ)); - - else - Add_Check - (Compile_Time_Constraint_Error - (Wnode, - "static value out of range of}??", T_Typ)); - end if; - end if; - - else - Cond := Discrete_Expr_Cond (Ck_Node, T_Typ); - end if; - end; - - -- Here for the case of a non-static expression, we need a runtime - -- check unless the source type range is guaranteed to be in the - -- range of the target type. - - else - if not In_Subrange_Of (S_Typ, T_Typ) then - Cond := Discrete_Expr_Cond (Ck_Node, T_Typ); - end if; - end if; - end if; - - if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then - if Is_Constrained (T_Typ) then - - Expr_Actual := Get_Referenced_Object (Ck_Node); - Exptyp := Get_Actual_Subtype (Expr_Actual); - - if Is_Access_Type (Exptyp) then - Exptyp := Designated_Type (Exptyp); - end if; - - -- String_Literal case. This needs to be handled specially be- - -- cause no index types are available for string literals. The - -- condition is simply: - - -- T_Typ'Length = string-literal-length - - if Nkind (Expr_Actual) = N_String_Literal then - null; - - -- General array case. Here we have a usable actual subtype for - -- the expression, and the condition is built from the two types - - -- T_Typ'First < Exptyp'First or else - -- T_Typ'Last > Exptyp'Last or else - -- T_Typ'First(1) < Exptyp'First(1) or else - -- T_Typ'Last(1) > Exptyp'Last(1) or else - -- ... - - elsif Is_Constrained (Exptyp) then - declare - Ndims : constant Nat := Number_Dimensions (T_Typ); - - L_Index : Node_Id; - R_Index : Node_Id; - - begin - L_Index := First_Index (T_Typ); - R_Index := First_Index (Exptyp); - - for Indx in 1 .. Ndims loop - if not (Nkind (L_Index) = N_Raise_Constraint_Error - or else - Nkind (R_Index) = N_Raise_Constraint_Error) - then - -- Deal with compile time length check. Note that we - -- skip this in the access case, because the access - -- value may be null, so we cannot know statically. - - if not - Subtypes_Statically_Match - (Etype (L_Index), Etype (R_Index)) - then - -- If the target type is constrained then we - -- have to check for exact equality of bounds - -- (required for qualified expressions). - - if Is_Constrained (T_Typ) then - Evolve_Or_Else - (Cond, - Range_Equal_E_Cond (Exptyp, T_Typ, Indx)); - else - Evolve_Or_Else - (Cond, Range_E_Cond (Exptyp, T_Typ, Indx)); - end if; - end if; - - Next (L_Index); - Next (R_Index); - end if; - end loop; - end; - - -- Handle cases where we do not get a usable actual subtype that - -- is constrained. This happens for example in the function call - -- and explicit dereference cases. In these cases, we have to get - -- the length or range from the expression itself, making sure we - -- do not evaluate it more than once. - - -- Here Ck_Node is the original expression, or more properly the - -- result of applying Duplicate_Expr to the original tree, - -- forcing the result to be a name. - - else - declare - Ndims : constant Nat := Number_Dimensions (T_Typ); - - begin - -- Build the condition for the explicit dereference case - - for Indx in 1 .. Ndims loop - Evolve_Or_Else - (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx)); - end loop; - end; - end if; - - else - -- For a conversion to an unconstrained array type, generate an - -- Action to check that the bounds of the source value are within - -- the constraints imposed by the target type (RM 4.6(38)). No - -- check is needed for a conversion to an access to unconstrained - -- array type, as 4.6(24.15/2) requires the designated subtypes - -- of the two access types to statically match. - - if Nkind (Parent (Ck_Node)) = N_Type_Conversion - and then not Do_Access - then - declare - Opnd_Index : Node_Id; - Targ_Index : Node_Id; - Opnd_Range : Node_Id; - - begin - Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node)); - Targ_Index := First_Index (T_Typ); - while Present (Opnd_Index) loop - - -- If the index is a range, use its bounds. If it is an - -- entity (as will be the case if it is a named subtype - -- or an itype created for a slice) retrieve its range. - - if Is_Entity_Name (Opnd_Index) - and then Is_Type (Entity (Opnd_Index)) - then - Opnd_Range := Scalar_Range (Entity (Opnd_Index)); - else - Opnd_Range := Opnd_Index; - end if; - - if Nkind (Opnd_Range) = N_Range then - if Is_In_Range - (Low_Bound (Opnd_Range), Etype (Targ_Index), - Assume_Valid => True) - and then - Is_In_Range - (High_Bound (Opnd_Range), Etype (Targ_Index), - Assume_Valid => True) - then - null; - - -- If null range, no check needed - - elsif - Compile_Time_Known_Value (High_Bound (Opnd_Range)) - and then - Compile_Time_Known_Value (Low_Bound (Opnd_Range)) - and then - Expr_Value (High_Bound (Opnd_Range)) < - Expr_Value (Low_Bound (Opnd_Range)) - then - null; - - elsif Is_Out_Of_Range - (Low_Bound (Opnd_Range), Etype (Targ_Index), - Assume_Valid => True) - or else - Is_Out_Of_Range - (High_Bound (Opnd_Range), Etype (Targ_Index), - Assume_Valid => True) - then - Add_Check - (Compile_Time_Constraint_Error - (Wnode, "value out of range of}??", T_Typ)); - - else - Evolve_Or_Else - (Cond, - Discrete_Range_Cond - (Opnd_Range, Etype (Targ_Index))); - end if; - end if; - - Next_Index (Opnd_Index); - Next_Index (Targ_Index); - end loop; - end; - end if; - end if; - end if; - - -- Construct the test and insert into the tree - - if Present (Cond) then - if Do_Access then - Cond := Guard_Access (Cond, Loc, Ck_Node); - end if; - - Add_Check - (Make_Raise_Constraint_Error (Loc, - Condition => Cond, - Reason => CE_Range_Check_Failed)); - end if; - - return Ret_Result; - end Selected_Range_Checks; - - ------------------------------- - -- Storage_Checks_Suppressed -- - ------------------------------- - - function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is - begin - if Present (E) and then Checks_May_Be_Suppressed (E) then - return Is_Check_Suppressed (E, Storage_Check); - else - return Scope_Suppress.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); - end if; - - return Scope_Suppress.Suppress (Tag_Check); - end Tag_Checks_Suppressed; - - -------------------------- - -- Validity_Check_Range -- - -------------------------- - - procedure Validity_Check_Range (N : Node_Id) is - begin - if Validity_Checks_On and Validity_Check_Operands then - if Nkind (N) = N_Range then - Ensure_Valid (Low_Bound (N)); - Ensure_Valid (High_Bound (N)); - end if; - end if; - end Validity_Check_Range; - - -------------------------------- - -- Validity_Checks_Suppressed -- - -------------------------------- - - function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is - begin - if Present (E) and then Checks_May_Be_Suppressed (E) then - return Is_Check_Suppressed (E, Validity_Check); - else - return Scope_Suppress.Suppress (Validity_Check); - end if; - end Validity_Checks_Suppressed; - -end Checks; |