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