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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- C H E C K S --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2003 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. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Atree; use Atree;
with Debug; use Debug;
with Einfo; use Einfo;
with Errout; use Errout;
with Exp_Ch2; use Exp_Ch2;
with Exp_Util; use Exp_Util;
with Elists; use Elists;
with Freeze; use Freeze;
with Lib; use Lib;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Output; use Output;
with Restrict; use Restrict;
with Rtsfind; use Rtsfind;
with Sem; use Sem;
with Sem_Eval; use Sem_Eval;
with Sem_Ch8; use Sem_Ch8;
with Sem_Res; use Sem_Res;
with Sem_Util; use Sem_Util;
with Sem_Warn; use Sem_Warn;
with Sinfo; use Sinfo;
with Sinput; use Sinput;
with Snames; use Snames;
with Sprint; use Sprint;
with Stand; use Stand;
with Targparm; use Targparm;
with Tbuild; use Tbuild;
with Ttypes; use Ttypes;
with Urealp; use Urealp;
with Validsw; use Validsw;
package body Checks is
-- General note: many of these routines are concerned with generating
-- checking code to make sure that constraint error is raised at runtime.
-- Clearly this code is only needed if the expander is active, since
-- otherwise we will not be generating code or going into the runtime
-- execution anyway.
-- We therefore disconnect most of these checks if the expander is
-- inactive. This has the additional benefit that we do not need to
-- worry about the tree being messed up by previous errors (since errors
-- turn off expansion anyway).
-- There are a few exceptions to the above rule. For instance routines
-- such as Apply_Scalar_Range_Check that do not insert any code can be
-- safely called even when the Expander is inactive (but Errors_Detected
-- is 0). The benefit of executing this code when expansion is off, is
-- the ability to emit constraint error warning for static expressions
-- even when we are not generating code.
-------------------------------------
-- Suppression of Redundant Checks --
-------------------------------------
-- This unit implements a limited circuit for removal of redundant
-- checks. The processing is based on a tracing of simple sequential
-- flow. For any sequence of statements, we save expressions that are
-- marked to be checked, and then if the same expression appears later
-- with the same check, then under certain circumstances, the second
-- check can be suppressed.
-- Basically, we can suppress the check if we know for certain that
-- the previous expression has been elaborated (together with its
-- check), and we know that the exception frame is the same, and that
-- nothing has happened to change the result of the exception.
-- Let us examine each of these three conditions in turn to describe
-- how we ensure that this condition is met.
-- First, we need to know for certain that the previous expression has
-- been executed. This is done principly by the mechanism of calling
-- Conditional_Statements_Begin at the start of any statement sequence
-- and Conditional_Statements_End at the end. The End call causes all
-- checks remembered since the Begin call to be discarded. This does
-- miss a few cases, notably the case of a nested BEGIN-END block with
-- no exception handlers. But the important thing is to be conservative.
-- The other protection is that all checks are discarded if a label
-- is encountered, since then the assumption of sequential execution
-- is violated, and we don't know enough about the flow.
-- Second, we need to know that the exception frame is the same. We
-- do this by killing all remembered checks when we enter a new frame.
-- Again, that's over-conservative, but generally the cases we can help
-- with are pretty local anyway (like the body of a loop for example).
-- Third, we must be sure to forget any checks which are no longer valid.
-- This is done by two mechanisms, first the Kill_Checks_Variable call is
-- used to note any changes to local variables. We only attempt to deal
-- with checks involving local variables, so we do not need to worry
-- about global variables. Second, a call to any non-global procedure
-- causes us to abandon all stored checks, since such a all may affect
-- the values of any local variables.
-- The following define the data structures used to deal with remembering
-- checks so that redundant checks can be eliminated as described above.
-- Right now, the only expressions that we deal with are of the form of
-- simple local objects (either declared locally, or IN parameters) or
-- such objects plus/minus a compile time known constant. We can do
-- more later on if it seems worthwhile, but this catches many simple
-- cases in practice.
-- The following record type reflects a single saved check. An entry
-- is made in the stack of saved checks if and only if the expression
-- has been elaborated with the indicated checks.
type Saved_Check is record
Killed : Boolean;
-- Set True if entry is killed by Kill_Checks
Entity : Entity_Id;
-- The entity involved in the expression that is checked
Offset : Uint;
-- A compile time value indicating the result of adding or
-- subtracting a compile time value. This value is to be
-- added to the value of the Entity. A value of zero is
-- used for the case of a simple entity reference.
Check_Type : Character;
-- This is set to 'R' for a range check (in which case Target_Type
-- is set to the target type for the range check) or to 'O' for an
-- overflow check (in which case Target_Type is set to Empty).
Target_Type : Entity_Id;
-- Used only if Do_Range_Check is set. Records the target type for
-- the check. We need this, because a check is a duplicate only if
-- it has a the same target type (or more accurately one with a
-- range that is smaller or equal to the stored target type of a
-- saved check).
end record;
-- The following table keeps track of saved checks. Rather than use an
-- extensible table. We just use a table of fixed size, and we discard
-- any saved checks that do not fit. That's very unlikely to happen and
-- this is only an optimization in any case.
Saved_Checks : array (Int range 1 .. 200) of Saved_Check;
-- Array of saved checks
Num_Saved_Checks : Nat := 0;
-- Number of saved checks
-- The following stack keeps track of statement ranges. It is treated
-- as a stack. When Conditional_Statements_Begin is called, an entry
-- is pushed onto this stack containing the value of Num_Saved_Checks
-- at the time of the call. Then when Conditional_Statements_End is
-- called, this value is popped off and used to reset Num_Saved_Checks.
-- Note: again, this is a fixed length stack with a size that should
-- always be fine. If the value of the stack pointer goes above the
-- limit, then we just forget all saved checks.
Saved_Checks_Stack : array (Int range 1 .. 100) of Nat;
Saved_Checks_TOS : Nat := 0;
-----------------------
-- Local Subprograms --
-----------------------
procedure Apply_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.
procedure Find_Check
(Expr : Node_Id;
Check_Type : Character;
Target_Type : Entity_Id;
Entry_OK : out Boolean;
Check_Num : out Nat;
Ent : out Entity_Id;
Ofs : out Uint);
-- This routine is used by Enable_Range_Check and Enable_Overflow_Check
-- to see if a check is of the form for optimization, and if so, to see
-- if it has already been performed. Expr is the expression to check,
-- and Check_Type is 'R' for a range check, 'O' for an overflow check.
-- Target_Type is the target type for a range check, and Empty for an
-- overflow check. If the entry is not of the form for optimization,
-- then Entry_OK is set to False, and the remaining out parameters
-- are undefined. If the entry is OK, then Ent/Ofs are set to the
-- entity and offset from the expression. Check_Num is the number of
-- a matching saved entry in Saved_Checks, or zero if no such entry
-- is located.
function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id;
-- If a discriminal is used in constraining a prival, Return reference
-- to the discriminal of the protected body (which renames the parameter
-- of the enclosing protected operation). This clumsy transformation is
-- needed because privals are created too late and their actual subtypes
-- are not available when analysing the bodies of the protected operations.
-- 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
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Access_Check);
else
return Scope_Suppress (Access_Check);
end if;
end Access_Checks_Suppressed;
-------------------------------------
-- Accessibility_Checks_Suppressed --
-------------------------------------
function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Accessibility_Check);
else
return Scope_Suppress (Accessibility_Check);
end if;
end Accessibility_Checks_Suppressed;
-------------------------
-- Append_Range_Checks --
-------------------------
procedure Append_Range_Checks
(Checks : Check_Result;
Stmts : List_Id;
Suppress_Typ : Entity_Id;
Static_Sloc : Source_Ptr;
Flag_Node : Node_Id)
is
Internal_Flag_Node : constant Node_Id := Flag_Node;
Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
Checks_On : constant Boolean :=
(not Index_Checks_Suppressed (Suppress_Typ))
or else
(not Range_Checks_Suppressed (Suppress_Typ));
begin
-- For now we just return if Checks_On is false, however this should
-- be enhanced to check for an always True value in the condition
-- and to generate a compilation warning???
if not Checks_On then
return;
end if;
for J in 1 .. 2 loop
exit when No (Checks (J));
if Nkind (Checks (J)) = N_Raise_Constraint_Error
and then Present (Condition (Checks (J)))
then
if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
Append_To (Stmts, Checks (J));
Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
end if;
else
Append_To
(Stmts,
Make_Raise_Constraint_Error (Internal_Static_Sloc,
Reason => CE_Range_Check_Failed));
end if;
end loop;
end Append_Range_Checks;
------------------------
-- Apply_Access_Check --
------------------------
procedure Apply_Access_Check (N : Node_Id) is
P : constant Node_Id := Prefix (N);
begin
if Inside_A_Generic then
return;
end if;
if Is_Entity_Name (P) then
Check_Unset_Reference (P);
end if;
-- Don't need access check if prefix is known to be non-null
if Known_Non_Null (P) then
return;
-- Don't need access checks if they are suppressed on the type
elsif Access_Checks_Suppressed (Etype (P)) then
return;
end if;
-- Case where P is an entity name
if Is_Entity_Name (P) then
declare
Ent : constant Entity_Id := Entity (P);
begin
if Access_Checks_Suppressed (Ent) then
return;
end if;
-- Otherwise we are going to generate an access check, and
-- are we have done it, the entity will now be known non null
-- But we have to check for safe sequential semantics here!
if Safe_To_Capture_Value (N, Ent) then
Set_Is_Known_Non_Null (Ent);
end if;
end;
end if;
-- Access check is required
declare
Loc : constant Source_Ptr := Sloc (N);
begin
Insert_Action (N,
Make_Raise_Constraint_Error (Sloc (N),
Condition =>
Make_Op_Eq (Loc,
Left_Opnd => Duplicate_Subexpr_Move_Checks (P),
Right_Opnd =>
Make_Null (Loc)),
Reason => CE_Access_Check_Failed));
end;
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),
Reason => PE_Accessibility_Check_Failed));
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;
Alignment_Required : constant Boolean := Maximum_Alignment > 1;
-- Constant to show whether target requires alignment checks
begin
-- See if check needed. Note that we never need a check if the
-- maximum alignment is one, since the check will always succeed
if No (AC)
or else not Check_Address_Alignment (AC)
or else not Alignment_Required
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,
Reason => PE_Misaligned_Address_Value));
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_No_Checks (Expr)),
Right_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (E, Loc),
Attribute_Name => Name_Alignment)),
Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
Reason => PE_Misaligned_Address_Value),
Suppress => All_Checks);
end if;
end if;
return;
exception
when RE_Not_Available =>
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;
begin
-- Skip this if overflow checks are done in back end, or the overflow
-- flag is not set anyway, or we are not doing code expansion.
if Backend_Overflow_Checks_On_Target
or not Do_Overflow_Check (N)
or not Expander_Active
then
return;
end if;
-- Otherwise, we generate the full general code for front end overflow
-- detection, which works by doing arithmetic in a larger type:
-- x op y
-- is expanded into
-- Typ (Checktyp (x) op Checktyp (y));
-- where Typ is the type of the original expression, and Checktyp is
-- an integer type of sufficient length to hold the largest possible
-- result.
-- 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);
-- In the discrete type case, we directly generate the range check
-- for the outer operand. This range check will implement the required
-- overflow check.
if Is_Discrete_Type (Typ) then
Rewrite (N, Opnd);
Generate_Range_Check (Expression (N), Typ, CE_Overflow_Check_Failed);
-- For other types, we enable overflow checking on the conversion,
-- after setting the node as analyzed to prevent recursive attempts
-- to expand the conversion node.
else
Set_Analyzed (Opnd, True);
Enable_Overflow_Check (Opnd);
Rewrite (N, Opnd);
end if;
exception
when RE_Not_Available =>
return;
end 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,
Reason => SE_Object_Too_Large));
Error_Msg_N ("?Storage_Error will be raised at run-time", N);
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)),
Reason => SE_Object_Too_Large);
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 No (Param_Entity (Lhs)))
then
if (Etype (N) = Typ
or else (Do_Access and then Designated_Type (Typ) = S_Typ))
and then not Is_Aliased_View (Lhs)
then
return;
end if;
-- We can also eliminate checks on allocators with a subtype mark
-- that coincides with the context type. The context type may be a
-- subtype without a constraint (common case, a generic actual).
elsif Nkind (Original_Node (N)) = N_Allocator
and then Is_Entity_Name (Expression (Original_Node (N)))
then
declare
Alloc_Typ : constant Entity_Id :=
Entity (Expression (Original_Node (N)));
begin
if Alloc_Typ = T_Typ
or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
and then Is_Entity_Name (
Subtype_Indication (Parent (T_Typ)))
and then Alloc_Typ = Base_Type (T_Typ))
then
return;
end if;
end;
end if;
-- See if we have a case where the types are both constrained, and
-- all the constraints are constants. In this case, we can do the
-- check successfully at compile time.
-- We skip this check for the case where the node is a rewritten`
-- allocator, because it already carries the context subtype, and
-- extracting the discriminants from the aggregate is messy.
if Is_Constrained (S_Typ)
and then Nkind (Original_Node (N)) /= N_Allocator
then
declare
DconT : Elmt_Id;
Discr : Entity_Id;
DconS : Elmt_Id;
ItemS : Node_Id;
ItemT : Node_Id;
begin
-- S_Typ may not have discriminants in the case where it is a
-- private type completed by a default discriminated type. In
-- that case, we need to get the constraints from the
-- underlying_type. If the underlying type is unconstrained (i.e.
-- has no default discriminants) no check is needed.
if Has_Discriminants (S_Typ) then
Discr := First_Discriminant (S_Typ);
DconS := First_Elmt (Discriminant_Constraint (S_Typ));
else
Discr := First_Discriminant (Underlying_Type (S_Typ));
DconS :=
First_Elmt
(Discriminant_Constraint (Underlying_Type (S_Typ)));
if No (DconS) then
return;
end if;
-- A further optimization: if T_Typ is derived from S_Typ
-- without imposing a constraint, no check is needed.
if Nkind (Original_Node (Parent (T_Typ))) =
N_Full_Type_Declaration
then
declare
Type_Def : constant Node_Id :=
Type_Definition
(Original_Node (Parent (T_Typ)));
begin
if Nkind (Type_Def) = N_Derived_Type_Definition
and then Is_Entity_Name (Subtype_Indication (Type_Def))
and then Entity (Subtype_Indication (Type_Def)) = S_Typ
then
return;
end if;
end;
end if;
end if;
DconT := First_Elmt (Discriminant_Constraint (T_Typ));
while Present (Discr) loop
ItemS := Node (DconS);
ItemT := Node (DconT);
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&?",
CE_Discriminant_Check_Failed, Ent => Discr);
return;
end if;
end if;
Next_Elmt (DconS);
Next_Elmt (DconT);
Next_Discriminant (Discr);
end loop;
if No (Discr) then
return;
end if;
end;
end if;
-- Here we need a discriminant check. First build the expression
-- for the comparisons of the discriminants:
-- (n.disc1 /= typ.disc1) or else
-- (n.disc2 /= typ.disc2) or else
-- ...
-- (n.discn /= typ.discn)
Cond := Build_Discriminant_Checks (N, T_Typ);
-- If Lhs is set and is a parameter, then the condition is
-- guarded by: lhs'constrained and then (condition built above)
if Present (Param_Entity (Lhs)) then
Cond :=
Make_And_Then (Loc,
Left_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
Attribute_Name => Name_Constrained),
Right_Opnd => Cond);
end if;
if Do_Access then
Cond := Guard_Access (Cond, Loc, N);
end if;
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition => Cond,
Reason => CE_Discriminant_Check_Failed));
end Apply_Discriminant_Check;
------------------------
-- Apply_Divide_Check --
------------------------
procedure Apply_Divide_Check (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
LLB : Uint;
Llo : Uint;
Lhi : Uint;
LOK : Boolean;
Rlo : Uint;
Rhi : Uint;
ROK : Boolean;
begin
if Expander_Active
and not Backend_Divide_Checks_On_Target
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_Move_Checks (Right),
Right_Opnd => Make_Integer_Literal (Loc, 0)),
Reason => CE_Divide_By_Zero));
end if;
end if;
-- Test for extremely annoying case of xxx'First divided by -1
if Do_Overflow_Check (N) then
if Nkind (N) = N_Op_Divide
and then Is_Signed_Integer_Type (Typ)
then
Determine_Range (Left, LOK, Llo, Lhi);
LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
and then
((not LOK) or else (Llo = LLB))
then
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_And_Then (Loc,
Make_Op_Eq (Loc,
Left_Opnd =>
Duplicate_Subexpr_Move_Checks (Left),
Right_Opnd => Make_Integer_Literal (Loc, LLB)),
Make_Op_Eq (Loc,
Left_Opnd =>
Duplicate_Subexpr (Right),
Right_Opnd =>
Make_Integer_Literal (Loc, -1))),
Reason => CE_Overflow_Check_Failed));
end if;
end if;
end if;
end if;
end Apply_Divide_Check;
------------------------
-- Apply_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
---------------
-- Bad_Value --
---------------
procedure Bad_Value is
begin
Apply_Compile_Time_Constraint_Error
(Expr, "value not in range of}?", CE_Range_Check_Failed,
Ent => Target_Typ,
Typ => Target_Typ);
end Bad_Value;
-- Start of processing for Apply_Scalar_Range_Check
begin
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 Index_Checks_Suppressed (Base_Type (Arr_Typ))
then
return;
-- Check array itself if it is an entity name
elsif Is_Entity_Name (Arr)
and then Index_Checks_Suppressed (Entity (Arr))
then
return;
-- Check expression itself if it is an entity name
elsif Is_Entity_Name (Expr)
and then Index_Checks_Suppressed (Entity (Expr))
then
return;
end if;
-- All other cases, check for Range_Checks suppressed
else
-- Check target type and its base type
if Range_Checks_Suppressed (Target_Typ)
or else Range_Checks_Suppressed (Base_Type (Target_Typ))
then
return;
-- Check expression itself if it is an entity name
elsif Is_Entity_Name (Expr)
and then Range_Checks_Suppressed (Entity (Expr))
then
return;
-- If Expr is part of an assignment statement, then check
-- left side of assignment if it is an entity name.
elsif Nkind (Parnt) = N_Assignment_Statement
and then Is_Entity_Name (Name (Parnt))
and then Range_Checks_Suppressed (Entity (Name (Parnt)))
then
return;
end if;
end if;
end if;
-- Do not set range checks if they are killed
if Nkind (Expr) = N_Unchecked_Type_Conversion
and then Kill_Range_Check (Expr)
then
return;
end if;
-- Do not set range checks for any values from System.Scalar_Values
-- since the whole idea of such values is to avoid checking them!
if Is_Entity_Name (Expr)
and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
then
return;
end if;
-- Now see if we need a check
if No (Source_Typ) then
S_Typ := Etype (Expr);
else
S_Typ := Source_Typ;
end if;
if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
return;
end if;
Is_Unconstrained_Subscr_Ref :=
Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
-- Always do a range check if the source type includes infinities
-- and the target type does not include infinities. We do not do
-- this if range checks are killed.
if Is_Floating_Point_Type (S_Typ)
and then Has_Infinities (S_Typ)
and then not Has_Infinities (Target_Typ)
then
Enable_Range_Check (Expr);
end if;
-- Return if we know expression is definitely in the range of
-- the target type as determined by Determine_Range. Right now
-- we only do this for discrete types, and not fixed-point or
-- floating-point types.
-- The additional less-precise tests below catch these cases.
-- Note: skip this if we are given a source_typ, since the point
-- of supplying a Source_Typ is to stop us looking at the expression.
-- could sharpen this test to be out parameters only ???
if Is_Discrete_Type (Target_Typ)
and then Is_Discrete_Type (Etype (Expr))
and then not Is_Unconstrained_Subscr_Ref
and then No (Source_Typ)
then
declare
Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
Thi : constant Node_Id := Type_High_Bound (Target_Typ);
Lo : Uint;
Hi : Uint;
begin
if Compile_Time_Known_Value (Tlo)
and then Compile_Time_Known_Value (Thi)
then
declare
Lov : constant Uint := Expr_Value (Tlo);
Hiv : constant Uint := Expr_Value (Thi);
begin
-- If range is null, we for sure have a constraint error
-- (we don't even need to look at the value involved,
-- since all possible values will raise CE).
if Lov > Hiv then
Bad_Value;
return;
end if;
-- Otherwise determine range of value
Determine_Range (Expr, OK, Lo, Hi);
if OK then
-- If definitely in range, all OK
if Lo >= Lov and then Hi <= Hiv then
return;
-- If definitely not in range, warn
elsif Lov > Hi or else Hiv < Lo then
Bad_Value;
return;
-- Otherwise we don't know
else
null;
end if;
end if;
end;
end if;
end;
end if;
Int_Real :=
Is_Floating_Point_Type (S_Typ)
or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
-- Check if we can determine at compile time whether Expr is in the
-- range of the target type. Note that if S_Typ is within the bounds
-- of Target_Typ then this must be the case. This check is meaningful
-- only if this is not a conversion between integer and real types.
if not Is_Unconstrained_Subscr_Ref
and then
Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
and then
(In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
or else
Is_In_Range (Expr, Target_Typ, Fixed_Int, Int_Real))
then
return;
elsif Is_Out_Of_Range (Expr, Target_Typ, Fixed_Int, Int_Real) then
Bad_Value;
return;
-- In the floating-point case, we only do range checks if the
-- type is constrained. We definitely do NOT want range checks
-- for unconstrained types, since we want to have infinities
elsif Is_Floating_Point_Type (S_Typ) then
if Is_Constrained (S_Typ) then
Enable_Range_Check (Expr);
end if;
-- For all other cases we enable a range check unconditionally
else
Enable_Range_Check (Expr);
return;
end if;
end Apply_Scalar_Range_Check;
----------------------------------
-- Apply_Selected_Length_Checks --
----------------------------------
procedure Apply_Selected_Length_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Do_Static : Boolean)
is
Cond : Node_Id;
R_Result : Check_Result;
R_Cno : Node_Id;
Loc : constant Source_Ptr := Sloc (Ck_Node);
Checks_On : constant Boolean :=
(not Index_Checks_Suppressed (Target_Typ))
or else
(not Length_Checks_Suppressed (Target_Typ));
begin
if not Expander_Active then
return;
end if;
R_Result :=
Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
for J in 1 .. 2 loop
R_Cno := R_Result (J);
exit when No (R_Cno);
-- A length check may mention an Itype which is attached to a
-- subsequent node. At the top level in a package this can cause
-- an order-of-elaboration problem, so we make sure that the itype
-- is referenced now.
if Ekind (Current_Scope) = E_Package
and then Is_Compilation_Unit (Current_Scope)
then
Ensure_Defined (Target_Typ, Ck_Node);
if Present (Source_Typ) then
Ensure_Defined (Source_Typ, Ck_Node);
elsif Is_Itype (Etype (Ck_Node)) then
Ensure_Defined (Etype (Ck_Node), Ck_Node);
end if;
end if;
-- If the item is a conditional raise of constraint error,
-- then have a look at what check is being performed and
-- ???
if Nkind (R_Cno) = N_Raise_Constraint_Error
and then Present (Condition (R_Cno))
then
Cond := Condition (R_Cno);
if not Has_Dynamic_Length_Check (Ck_Node)
and then Checks_On
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}?",
CE_Length_Check_Failed,
Ent => Target_Typ,
Typ => Target_Typ);
-- If we were only doing a static check, or if checks are not
-- on, then we want to delete the check, since it is not needed.
-- We do this by replacing the if statement by a null statement
elsif Do_Static or else not Checks_On then
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}?",
CE_Range_Check_Failed,
Ent => Target_Typ,
Typ => Target_Typ);
Set_Raises_Constraint_Error (Ck_Node);
else
Apply_Compile_Time_Constraint_Error
(Ck_Node, "static value out of range of}?",
CE_Range_Check_Failed,
Ent => Target_Typ,
Typ => Target_Typ);
end if;
-- If we were only doing a static check, or if checks are not
-- on, then we want to delete the check, since it is not needed.
-- We do this by replacing the if statement by a null statement
elsif Do_Static or else not Checks_On then
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 serious errors detected, there are some nasty
-- situations of incomplete trees that blow things up.
elsif Serious_Errors_Detected > 0 then
return;
-- Scalar type conversions of the form Target_Type (Expr) require
-- a range check if we cannot be sure that Expr is in the base type
-- of Target_Typ and also that Expr is in the range of Target_Typ.
-- These are not quite the same condition from an implementation
-- point of view, but clearly the second includes the first.
elsif Is_Scalar_Type (Target_Type) then
declare
Conv_OK : constant Boolean := Conversion_OK (N);
-- If the Conversion_OK flag on the type conversion is set
-- and no floating point type is involved in the type conversion
-- then fixed point values must be read as integral values.
begin
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 (Stored_Constraint (Target_Type))
then
-- An unconstrained derived type may have inherited discriminant
-- Build an actual discriminant constraint list using the stored
-- constraint, to verify that the expression of the parent type
-- satisfies the constraints imposed by the (unconstrained!)
-- derived type. This applies to value conversions, not to view
-- conversions of tagged types.
declare
Loc : constant Source_Ptr := Sloc (N);
Cond : Node_Id;
Constraint : Elmt_Id;
Discr_Value : Node_Id;
Discr : Entity_Id;
New_Constraints : constant Elist_Id := New_Elmt_List;
Old_Constraints : constant Elist_Id :=
Discriminant_Constraint (Expr_Type);
begin
Constraint := First_Elmt (Stored_Constraint (Target_Type));
while Present (Constraint) loop
Discr_Value := Node (Constraint);
if Is_Entity_Name (Discr_Value)
and then Ekind (Entity (Discr_Value)) = E_Discriminant
then
Discr := Corresponding_Discriminant (Entity (Discr_Value));
if Present (Discr)
and then Scope (Discr) = Base_Type (Expr_Type)
then
-- Parent is constrained by new discriminant. Obtain
-- Value of original discriminant in expression. If
-- the new discriminant has been used to constrain more
-- than one of the stored discriminants, this will
-- provide the required consistency check.
Append_Elmt (
Make_Selected_Component (Loc,
Prefix =>
Duplicate_Subexpr_No_Checks
(Expr, Name_Req => True),
Selector_Name =>
Make_Identifier (Loc, Chars (Discr))),
New_Constraints);
else
-- Discriminant of more remote ancestor ???
return;
end if;
-- Derived type definition has an explicit value for
-- this stored discriminant.
else
Append_Elmt
(Duplicate_Subexpr_No_Checks (Discr_Value),
New_Constraints);
end if;
Next_Elmt (Constraint);
end loop;
-- Use the unconstrained expression type to retrieve the
-- discriminants of the parent, and apply momentarily the
-- discriminant constraint synthesized above.
Set_Discriminant_Constraint (Expr_Type, New_Constraints);
Cond := Build_Discriminant_Checks (Expr, Expr_Type);
Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition => Cond,
Reason => CE_Discriminant_Check_Failed));
end;
-- For arrays, conversions are applied during expansion, to take
-- into accounts changes of representation. The checks become range
-- checks on the base type or length checks on the subtype, depending
-- on whether the target type is unconstrained or constrained.
else
null;
end if;
end Apply_Type_Conversion_Checks;
----------------------------------------------
-- Apply_Universal_Integer_Attribute_Checks --
----------------------------------------------
procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
begin
if Inside_A_Generic then
return;
-- Nothing to do if checks are suppressed
elsif Range_Checks_Suppressed (Typ)
and then Overflow_Checks_Suppressed (Typ)
then
return;
-- Nothing to do if the attribute does not come from source. The
-- internal attributes we generate of this type do not need checks,
-- and furthermore the attempt to check them causes some circular
-- elaboration orders when dealing with packed types.
elsif not Comes_From_Source (N) then
return;
-- If the prefix is a selected component that depends on a discriminant
-- the check may improperly expose a discriminant instead of using
-- the bounds of the object itself. Set the type of the attribute to
-- the base type of the context, so that a check will be imposed when
-- needed (e.g. if the node appears as an index).
elsif Nkind (Prefix (N)) = N_Selected_Component
and then Ekind (Typ) = E_Signed_Integer_Subtype
and then Depends_On_Discriminant (Scalar_Range (Typ))
then
Set_Etype (N, Base_Type (Typ));
-- Otherwise, replace the attribute node with a type conversion
-- node whose expression is the attribute, retyped to universal
-- integer, and whose subtype mark is the target type. The call
-- to analyze this conversion will set range and overflow checks
-- as required for proper detection of an out of range value.
else
Set_Etype (N, Universal_Integer);
Set_Analyzed (N, True);
Rewrite (N,
Make_Type_Conversion (Loc,
Subtype_Mark => New_Occurrence_Of (Typ, Loc),
Expression => Relocate_Node (N)));
Analyze_And_Resolve (N, Typ);
return;
end if;
end Apply_Universal_Integer_Attribute_Checks;
-------------------------------
-- Build_Discriminant_Checks --
-------------------------------
function Build_Discriminant_Checks
(N : Node_Id;
T_Typ : Entity_Id)
return Node_Id
is
Loc : constant Source_Ptr := Sloc (N);
Cond : Node_Id;
Disc : Elmt_Id;
Disc_Ent : Entity_Id;
Dref : Node_Id;
Dval : Node_Id;
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_No_Checks (Dval);
end if;
Dref :=
Make_Selected_Component (Loc,
Prefix =>
Duplicate_Subexpr_No_Checks (N, Name_Req => True),
Selector_Name =>
Make_Identifier (Loc, Chars (Disc_Ent)));
Set_Is_In_Discriminant_Check (Dref);
Evolve_Or_Else (Cond,
Make_Op_Ne (Loc,
Left_Opnd => Dref,
Right_Opnd => Dval));
Next_Elmt (Disc);
Next_Discriminant (Disc_Ent);
end loop;
return Cond;
end Build_Discriminant_Checks;
-----------------------------------
-- Check_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;
----------------------------------
-- Conditional_Statements_Begin --
----------------------------------
procedure Conditional_Statements_Begin is
begin
Saved_Checks_TOS := Saved_Checks_TOS + 1;
-- If stack overflows, kill all checks, that way we know to
-- simply reset the number of saved checks to zero on return.
-- This should never occur in practice.
if Saved_Checks_TOS > Saved_Checks_Stack'Last then
Kill_All_Checks;
-- In the normal case, we just make a new stack entry saving
-- the current number of saved checks for a later restore.
else
Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
if Debug_Flag_CC then
w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
Num_Saved_Checks);
end if;
end if;
end Conditional_Statements_Begin;
--------------------------------
-- Conditional_Statements_End --
--------------------------------
procedure Conditional_Statements_End is
begin
pragma Assert (Saved_Checks_TOS > 0);
-- If the saved checks stack overflowed, then we killed all
-- checks, so setting the number of saved checks back to
-- zero is correct. This should never occur in practice.
if Saved_Checks_TOS > Saved_Checks_Stack'Last then
Num_Saved_Checks := 0;
-- In the normal case, restore the number of saved checks
-- from the top stack entry.
else
Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
if Debug_Flag_CC then
w ("Conditional_Statements_End: Num_Saved_Checks = ",
Num_Saved_Checks);
end if;
end if;
Saved_Checks_TOS := Saved_Checks_TOS - 1;
end Conditional_Statements_End;
---------------------
-- Determine_Range --
---------------------
Cache_Size : constant := 2 ** 10;
type Cache_Index is range 0 .. Cache_Size - 1;
-- Determine size of below cache (power of 2 is more efficient!)
Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
Determine_Range_Cache_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
and then Lo_Right /= 0
then
if Lo_Right > 0 then
Lor := Uint_0;
Hir := Lo_Right - 1;
else -- Lo_Right < 0
Lor := Lo_Right + 1;
Hir := Uint_0;
end if;
else
OK1 := False;
end if;
end if;
-- For REM, if right operand is a positive constant, then
-- result must be in the allowable range of mod results.
when N_Op_Rem =>
if OK_Operands then
if Lo_Right = Hi_Right
and then Lo_Right /= 0
then
declare
Dval : constant Uint := (abs Lo_Right) - 1;
begin
-- The sign of the result depends on the sign of the
-- dividend (but not on the sign of the divisor, hence
-- the abs operation above).
if Lo_Left < 0 then
Lor := -Dval;
else
Lor := Uint_0;
end if;
if Hi_Left < 0 then
Hir := Uint_0;
else
Hir := Dval;
end if;
end;
else
OK1 := False;
end if;
end if;
-- Attribute reference cases
when N_Attribute_Reference =>
case Attribute_Name (N) is
-- For Pos/Val attributes, we can refine the range using the
-- possible range of values of the attribute expression
when Name_Pos | Name_Val =>
Determine_Range (First (Expressions (N)), OK1, Lor, Hir);
-- 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
if Present (E) then
if Is_Unchecked_Union (E) then
return True;
elsif Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Discriminant_Check);
end if;
end if;
return Scope_Suppress (Discriminant_Check);
end Discriminant_Checks_Suppressed;
--------------------------------
-- Division_Checks_Suppressed --
--------------------------------
function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Division_Check);
else
return Scope_Suppress (Division_Check);
end if;
end Division_Checks_Suppressed;
-----------------------------------
-- Elaboration_Checks_Suppressed --
-----------------------------------
function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) then
if Kill_Elaboration_Checks (E) then
return True;
elsif Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Elaboration_Check);
end if;
end if;
return Scope_Suppress (Elaboration_Check);
end Elaboration_Checks_Suppressed;
---------------------------
-- Enable_Overflow_Check --
---------------------------
procedure Enable_Overflow_Check (N : Node_Id) is
Typ : constant Entity_Id := Base_Type (Etype (N));
Chk : Nat;
OK : Boolean;
Ent : Entity_Id;
Ofs : Uint;
Lo : Uint;
Hi : Uint;
begin
if Debug_Flag_CC then
w ("Enable_Overflow_Check for node ", Int (N));
Write_Str (" Source location = ");
wl (Sloc (N));
pg (N);
end if;
-- Nothing to do if the range of the result is known OK. We skip
-- this for conversions, since the caller already did the check,
-- and in any case the condition for deleting the check for a
-- type conversion is different in any case.
if Nkind (N) /= N_Type_Conversion then
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 as being equal to the bounds of the
-- type, because it either can't tell anything more precise, or
-- does not think it is worth the effort to be more precise.
-- b) It is very unusual to have a situation in which this would
-- generate an unnecessary overflow check (an example would be
-- a subtype with a range 0 .. Integer'Last - 1 to which the
-- literal value one is added.
-- c) The alternative is a lot of special casing in this routine
-- which would partially duplicate Determine_Range processing.
if OK
and then Lo > Expr_Value (Type_Low_Bound (Typ))
and then Hi < Expr_Value (Type_High_Bound (Typ))
then
if Debug_Flag_CC then
w ("No overflow check required");
end if;
return;
end if;
end if;
-- If not in optimizing mode, set flag and we are done. We are also
-- done (and just set the flag) if the type is not a discrete type,
-- since it is not worth the effort to eliminate checks for other
-- than discrete types. In addition, we take this same path if we
-- have stored the maximum number of checks possible already (a
-- very unlikely situation, but we do not want to blow up!)
if Optimization_Level = 0
or else not Is_Discrete_Type (Etype (N))
or else Num_Saved_Checks = Saved_Checks'Last
then
Set_Do_Overflow_Check (N, True);
if Debug_Flag_CC then
w ("Optimization off");
end if;
return;
end if;
-- Otherwise evaluate and check the expression
Find_Check
(Expr => N,
Check_Type => 'O',
Target_Type => Empty,
Entry_OK => OK,
Check_Num => Chk,
Ent => Ent,
Ofs => Ofs);
if Debug_Flag_CC then
w ("Called Find_Check");
w (" OK = ", OK);
if OK then
w (" Check_Num = ", Chk);
w (" Ent = ", Int (Ent));
Write_Str (" Ofs = ");
pid (Ofs);
end if;
end if;
-- If check is not of form to optimize, then set flag and we are done
if not OK then
Set_Do_Overflow_Check (N, True);
return;
end if;
-- If check is already performed, then return without setting flag
if Chk /= 0 then
if Debug_Flag_CC then
w ("Check suppressed!");
end if;
return;
end if;
-- Here we will make a new entry for the new check
Set_Do_Overflow_Check (N, True);
Num_Saved_Checks := Num_Saved_Checks + 1;
Saved_Checks (Num_Saved_Checks) :=
(Killed => False,
Entity => Ent,
Offset => Ofs,
Check_Type => 'O',
Target_Type => Empty);
if Debug_Flag_CC then
w ("Make new entry, check number = ", Num_Saved_Checks);
w (" Entity = ", Int (Ent));
Write_Str (" Offset = ");
pid (Ofs);
w (" Check_Type = O");
w (" Target_Type = Empty");
end if;
-- If we get an exception, then something went wrong, probably because
-- of an error in the structure of the tree due to an incorrect program.
-- Or it may be a bug in the optimization circuit. In either case the
-- safest thing is simply to set the check flag unconditionally.
exception
when others =>
Set_Do_Overflow_Check (N, True);
if Debug_Flag_CC then
w (" exception occurred, overflow flag set");
end if;
return;
end Enable_Overflow_Check;
------------------------
-- Enable_Range_Check --
------------------------
procedure Enable_Range_Check (N : Node_Id) is
Chk : Nat;
OK : Boolean;
Ent : Entity_Id;
Ofs : Uint;
Ttyp : Entity_Id;
P : Node_Id;
begin
-- Return if unchecked type conversion with range check killed.
-- In this case we never set the flag (that's what Kill_Range_Check
-- is all about!)
if Nkind (N) = N_Unchecked_Type_Conversion
and then Kill_Range_Check (N)
then
return;
end if;
-- Debug trace output
if Debug_Flag_CC then
w ("Enable_Range_Check for node ", Int (N));
Write_Str (" Source location = ");
wl (Sloc (N));
pg (N);
end if;
-- If not in optimizing mode, set flag and we are done. We are also
-- done (and just set the flag) if the type is not a discrete type,
-- since it is not worth the effort to eliminate checks for other
-- than discrete types. In addition, we take this same path if we
-- have stored the maximum number of checks possible already (a
-- very unlikely situation, but we do not want to blow up!)
if Optimization_Level = 0
or else No (Etype (N))
or else not Is_Discrete_Type (Etype (N))
or else Num_Saved_Checks = Saved_Checks'Last
then
Set_Do_Range_Check (N, True);
if Debug_Flag_CC then
w ("Optimization off");
end if;
return;
end if;
-- Otherwise find out the target type
P := Parent (N);
-- For assignment, use left side subtype
if Nkind (P) = N_Assignment_Statement
and then Expression (P) = N
then
Ttyp := Etype (Name (P));
-- For indexed component, use subscript subtype
elsif Nkind (P) = N_Indexed_Component then
declare
Atyp : Entity_Id;
Indx : Node_Id;
Subs : Node_Id;
begin
Atyp := Etype (Prefix (P));
if Is_Access_Type (Atyp) then
Atyp := Designated_Type (Atyp);
end if;
Indx := First_Index (Atyp);
Subs := First (Expressions (P));
loop
if Subs = N then
Ttyp := Etype (Indx);
exit;
end if;
Next_Index (Indx);
Next (Subs);
end loop;
end;
-- For now, ignore all other cases, they are not so interesting
else
if Debug_Flag_CC then
w (" target type not found, flag set");
end if;
Set_Do_Range_Check (N, True);
return;
end if;
-- Evaluate and check the expression
Find_Check
(Expr => N,
Check_Type => 'R',
Target_Type => Ttyp,
Entry_OK => OK,
Check_Num => Chk,
Ent => Ent,
Ofs => Ofs);
if Debug_Flag_CC then
w ("Called Find_Check");
w ("Target_Typ = ", Int (Ttyp));
w (" OK = ", OK);
if OK then
w (" Check_Num = ", Chk);
w (" Ent = ", Int (Ent));
Write_Str (" Ofs = ");
pid (Ofs);
end if;
end if;
-- If check is not of form to optimize, then set flag and we are done
if not OK then
if Debug_Flag_CC then
w (" expression not of optimizable type, flag set");
end if;
Set_Do_Range_Check (N, True);
return;
end if;
-- If check is already performed, then return without setting flag
if Chk /= 0 then
if Debug_Flag_CC then
w ("Check suppressed!");
end if;
return;
end if;
-- Here we will make a new entry for the new check
Set_Do_Range_Check (N, True);
Num_Saved_Checks := Num_Saved_Checks + 1;
Saved_Checks (Num_Saved_Checks) :=
(Killed => False,
Entity => Ent,
Offset => Ofs,
Check_Type => 'R',
Target_Type => Ttyp);
if Debug_Flag_CC then
w ("Make new entry, check number = ", Num_Saved_Checks);
w (" Entity = ", Int (Ent));
Write_Str (" Offset = ");
pid (Ofs);
w (" Check_Type = R");
w (" Target_Type = ", Int (Ttyp));
pg (Ttyp);
end if;
-- If we get an exception, then something went wrong, probably because
-- of an error in the structure of the tree due to an incorrect program.
-- Or it may be a bug in the optimization circuit. In either case the
-- safest thing is simply to set the check flag unconditionally.
exception
when others =>
Set_Do_Range_Check (N, True);
if Debug_Flag_CC then
w (" exception occurred, range flag set");
end if;
return;
end Enable_Range_Check;
------------------
-- Ensure_Valid --
------------------
procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
Typ : constant Entity_Id := Etype (Expr);
begin
-- Ignore call if we are not doing any validity checking
if not Validity_Checks_On then
return;
-- Ignore call if range checks suppressed on entity in question
elsif Is_Entity_Name (Expr)
and then Range_Checks_Suppressed (Entity (Expr))
then
return;
-- No check required if expression is from the expander, we assume
-- the expander will generate whatever checks are needed. Note that
-- this is not just an optimization, it avoids infinite recursions!
-- Unchecked conversions must be checked, unless they are initialized
-- scalar values, as in a component assignment in an init proc.
-- In addition, we force a check if Force_Validity_Checks is set
elsif not Comes_From_Source (Expr)
and then not Force_Validity_Checks
and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
or else Kill_Range_Check (Expr))
then
return;
-- No check required if expression is known to have valid value
elsif Expr_Known_Valid (Expr) then
return;
-- 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 this
-- is an indirect or dispatching call, get signature from
-- the subprogram type.
if Nkind (P) = N_Procedure_Call_Statement then
L := Parameter_Associations (P);
if Is_Entity_Name (Name (P)) then
E := Entity (Name (P));
else
pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
E := Etype (Name (P));
end if;
-- Only need to worry if there are indeed actuals, and
-- if this could be a procedure call, otherwise we cannot
-- get a match (either we are not an argument, or the
-- mode of the formal is not OUT). This test also filters
-- out the generic case.
if Is_Non_Empty_List (L)
and then Is_Subprogram (E)
then
-- This is the loop through parameters, looking 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;
----------------
-- Find_Check --
----------------
procedure Find_Check
(Expr : Node_Id;
Check_Type : Character;
Target_Type : Entity_Id;
Entry_OK : out Boolean;
Check_Num : out Nat;
Ent : out Entity_Id;
Ofs : out Uint)
is
function Within_Range_Of
(Target_Type : Entity_Id;
Check_Type : Entity_Id)
return Boolean;
-- Given a requirement for checking a range against Target_Type, and
-- and a range Check_Type against which a check has already been made,
-- determines if the check against check type is sufficient to ensure
-- that no check against Target_Type is required.
---------------------
-- Within_Range_Of --
---------------------
function Within_Range_Of
(Target_Type : Entity_Id;
Check_Type : Entity_Id)
return Boolean
is
begin
if Target_Type = Check_Type then
return True;
else
declare
Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
Thi : constant Node_Id := Type_High_Bound (Target_Type);
Clo : constant Node_Id := Type_Low_Bound (Check_Type);
Chi : constant Node_Id := Type_High_Bound (Check_Type);
begin
if (Tlo = Clo
or else (Compile_Time_Known_Value (Tlo)
and then
Compile_Time_Known_Value (Clo)
and then
Expr_Value (Clo) >= Expr_Value (Tlo)))
and then
(Thi = Chi
or else (Compile_Time_Known_Value (Thi)
and then
Compile_Time_Known_Value (Chi)
and then
Expr_Value (Chi) <= Expr_Value (Clo)))
then
return True;
else
return False;
end if;
end;
end if;
end Within_Range_Of;
-- Start of processing for Find_Check
begin
-- Establish default, to avoid warnings from GCC.
Check_Num := 0;
-- Case of expression is simple entity reference
if Is_Entity_Name (Expr) then
Ent := Entity (Expr);
Ofs := Uint_0;
-- Case of expression is entity + known constant
elsif Nkind (Expr) = N_Op_Add
and then Compile_Time_Known_Value (Right_Opnd (Expr))
and then Is_Entity_Name (Left_Opnd (Expr))
then
Ent := Entity (Left_Opnd (Expr));
Ofs := Expr_Value (Right_Opnd (Expr));
-- Case of expression is entity - known constant
elsif Nkind (Expr) = N_Op_Subtract
and then Compile_Time_Known_Value (Right_Opnd (Expr))
and then Is_Entity_Name (Left_Opnd (Expr))
then
Ent := Entity (Left_Opnd (Expr));
Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
-- Any other expression is not of the right form
else
Ent := Empty;
Ofs := Uint_0;
Entry_OK := False;
return;
end if;
-- Come here with expression of appropriate form, check if
-- entity is an appropriate one for our purposes.
if (Ekind (Ent) = E_Variable
or else
Ekind (Ent) = E_Constant
or else
Ekind (Ent) = E_Loop_Parameter
or else
Ekind (Ent) = E_In_Parameter)
and then not Is_Library_Level_Entity (Ent)
then
Entry_OK := True;
else
Entry_OK := False;
return;
end if;
-- See if there is matching check already
for J in reverse 1 .. Num_Saved_Checks loop
declare
SC : Saved_Check renames Saved_Checks (J);
begin
if SC.Killed = False
and then SC.Entity = Ent
and then SC.Offset = Ofs
and then SC.Check_Type = Check_Type
and then Within_Range_Of (Target_Type, SC.Target_Type)
then
Check_Num := J;
return;
end if;
end;
end loop;
-- If we fall through entry was not found
Check_Num := 0;
return;
end Find_Check;
---------------------------------
-- Generate_Discriminant_Check --
---------------------------------
-- Note: the code for this procedure is derived from the
-- emit_discriminant_check routine a-trans.c v1.659.
procedure Generate_Discriminant_Check (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Pref : constant Node_Id := Prefix (N);
Sel : constant Node_Id := Selector_Name (N);
Orig_Comp : constant Entity_Id :=
Original_Record_Component (Entity (Sel));
-- The original component to be checked
Discr_Fct : constant Entity_Id :=
Discriminant_Checking_Func (Orig_Comp);
-- The discriminant checking function
Discr : Entity_Id;
-- One discriminant to be checked in the type
Real_Discr : Entity_Id;
-- Actual discriminant in the call
Pref_Type : Entity_Id;
-- Type of relevant prefix (ignoring private/access stuff)
Args : List_Id;
-- List of arguments for function call
Formal : Entity_Id;
-- Keep track of the formal corresponding to the actual we build
-- for each discriminant, in order to be able to perform the
-- necessary type conversions.
Scomp : Node_Id;
-- Selected component reference for checking function argument
begin
Pref_Type := Etype (Pref);
-- Force evaluation of the prefix, so that it does not get evaluated
-- twice (once for the check, once for the actual reference). Such a
-- double evaluation is always a potential source of inefficiency,
-- and is functionally incorrect in the volatile case, or when the
-- prefix may have side-effects. An entity or a component of an
-- entity requires no evaluation.
if Is_Entity_Name (Pref) then
if Treat_As_Volatile (Entity (Pref)) then
Force_Evaluation (Pref, Name_Req => True);
end if;
elsif Treat_As_Volatile (Etype (Pref)) then
Force_Evaluation (Pref, Name_Req => True);
elsif Nkind (Pref) = N_Selected_Component
and then Is_Entity_Name (Prefix (Pref))
then
null;
else
Force_Evaluation (Pref, Name_Req => True);
end if;
-- For a tagged type, use the scope of the original component to
-- obtain the type, because ???
if Is_Tagged_Type (Scope (Orig_Comp)) then
Pref_Type := Scope (Orig_Comp);
-- For an untagged derived type, use the discriminants of the
-- parent which have been renamed in the derivation, possibly
-- by a one-to-many discriminant constraint.
-- For non-tagged type, initially get the Etype of the prefix
else
if Is_Derived_Type (Pref_Type)
and then Number_Discriminants (Pref_Type) /=
Number_Discriminants (Etype (Base_Type (Pref_Type)))
then
Pref_Type := Etype (Base_Type (Pref_Type));
end if;
end if;
-- We definitely should have a checking function, This routine should
-- not be called if no discriminant checking function is present.
pragma Assert (Present (Discr_Fct));
-- Create the list of the actual parameters for the call. This list
-- is the list of the discriminant fields of the record expression to
-- be discriminant checked.
Args := New_List;
Formal := First_Formal (Discr_Fct);
Discr := First_Discriminant (Pref_Type);
while Present (Discr) loop
-- If we have a corresponding discriminant field, and a parent
-- subtype is present, then we want to use the corresponding
-- discriminant since this is the one with the useful value.
if Present (Corresponding_Discriminant (Discr))
and then Ekind (Pref_Type) = E_Record_Type
and then Present (Parent_Subtype (Pref_Type))
then
Real_Discr := Corresponding_Discriminant (Discr);
else
Real_Discr := Discr;
end if;
-- Construct the reference to the discriminant
Scomp :=
Make_Selected_Component (Loc,
Prefix =>
Unchecked_Convert_To (Pref_Type,
Duplicate_Subexpr (Pref)),
Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
-- Manually analyze and resolve this selected component. We really
-- want it just as it appears above, and do not want the expander
-- playing discriminal games etc with this reference. Then we
-- append the argument to the list we are gathering.
Set_Etype (Scomp, Etype (Real_Discr));
Set_Analyzed (Scomp, True);
Append_To (Args, Convert_To (Etype (Formal), Scomp));
Next_Formal_With_Extras (Formal);
Next_Discriminant (Discr);
end loop;
-- Now build and insert the call
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Function_Call (Loc,
Name => New_Occurrence_Of (Discr_Fct, Loc),
Parameter_Associations => Args),
Reason => CE_Discriminant_Check_Failed));
end Generate_Discriminant_Check;
----------------------------
-- Generate_Index_Checks --
----------------------------
procedure Generate_Index_Checks (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
A : constant Node_Id := Prefix (N);
Sub : Node_Id;
Ind : Nat;
Num : List_Id;
begin
Sub := First (Expressions (N));
Ind := 1;
while Present (Sub) loop
if Do_Range_Check (Sub) then
Set_Do_Range_Check (Sub, False);
-- Force evaluation except for the case of a simple name of
-- a non-volatile entity.
if not Is_Entity_Name (Sub)
or else Treat_As_Volatile (Entity (Sub))
then
Force_Evaluation (Sub);
end if;
-- Generate a raise of constraint error with the appropriate
-- reason and a condition of the form:
-- Base_Type(Sub) not in array'range (subscript)
-- Note that the reason we generate the conversion to the
-- base type here is that we definitely want the range check
-- to take place, even if it looks like the subtype is OK.
-- Optimization considerations that allow us to omit the
-- check have already been taken into account in the setting
-- of the Do_Range_Check flag earlier on.
if Ind = 1 then
Num := No_List;
else
Num := New_List (Make_Integer_Literal (Loc, Ind));
end if;
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd =>
Convert_To (Base_Type (Etype (Sub)),
Duplicate_Subexpr_Move_Checks (Sub)),
Right_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => Duplicate_Subexpr_Move_Checks (A),
Attribute_Name => Name_Range,
Expressions => Num)),
Reason => CE_Index_Check_Failed));
end if;
Ind := Ind + 1;
Next (Sub);
end loop;
end Generate_Index_Checks;
--------------------------
-- Generate_Range_Check --
--------------------------
procedure Generate_Range_Check
(N : Node_Id;
Target_Type : Entity_Id;
Reason : RT_Exception_Code)
is
Loc : constant Source_Ptr := Sloc (N);
Source_Type : constant Entity_Id := Etype (N);
Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
begin
-- First special case, if the source type is already within the
-- range of the target type, then no check is needed (probably we
-- should have stopped Do_Range_Check from being set in the first
-- place, but better late than later in preventing junk code!
-- We do NOT apply this if the source node is a literal, since in
-- this case the literal has already been labeled as having the
-- subtype of the target.
if In_Subrange_Of (Source_Type, Target_Type)
and then not
(Nkind (N) = N_Integer_Literal
or else
Nkind (N) = N_Real_Literal
or else
Nkind (N) = N_Character_Literal
or else
(Is_Entity_Name (N)
and then Ekind (Entity (N)) = E_Enumeration_Literal))
then
return;
end if;
-- We need a check, so force evaluation of the node, so that it does
-- not get evaluated twice (once for the check, once for the actual
-- reference). Such a double evaluation is always a potential source
-- of inefficiency, and is functionally incorrect in the volatile case.
if not Is_Entity_Name (N)
or else Treat_As_Volatile (Entity (N))
then
Force_Evaluation (N);
end if;
-- The easiest case is when Source_Base_Type and Target_Base_Type
-- are the same since in this case we can simply do a direct
-- check of the value of N against the bounds of Target_Type.
-- [constraint_error when N not in Target_Type]
-- Note: this is by far the most common case, for example all cases of
-- checks on the RHS of assignments are in this category, but not all
-- cases are like this. Notably conversions can involve two types.
if Source_Base_Type = Target_Base_Type then
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
Reason => Reason));
-- Next test for the case where the target type is within the bounds
-- of the base type of the source type, since in this case we can
-- simply convert these bounds to the base type of T to do the test.
-- [constraint_error when N not in
-- Source_Base_Type (Target_Type'First)
-- ..
-- Source_Base_Type(Target_Type'Last))]
-- The conversions will always work and need no check.
elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd =>
Make_Range (Loc,
Low_Bound =>
Convert_To (Source_Base_Type,
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_First)),
High_Bound =>
Convert_To (Source_Base_Type,
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_Last)))),
Reason => Reason));
-- Note that at this stage we now that the Target_Base_Type is
-- not in the range of the Source_Base_Type (since even the
-- Target_Type itself is not in this range). It could still be
-- the case that the Source_Type is in range of the target base
-- type, since we have not checked that case.
-- If that is the case, we can freely convert the source to the
-- target, and then test the target result against the bounds.
elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
-- We make a temporary to hold the value of the converted
-- value (converted to the base type), and then we will
-- do the test against this temporary.
-- Tnn : constant Target_Base_Type := Target_Base_Type (N);
-- [constraint_error when Tnn not in Target_Type]
-- Then the conversion itself is replaced by an occurrence of Tnn
declare
Tnn : constant Entity_Id :=
Make_Defining_Identifier (Loc,
Chars => New_Internal_Name ('T'));
begin
Insert_Actions (N, New_List (
Make_Object_Declaration (Loc,
Defining_Identifier => Tnn,
Object_Definition =>
New_Occurrence_Of (Target_Base_Type, Loc),
Constant_Present => True,
Expression =>
Make_Type_Conversion (Loc,
Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
Expression => Duplicate_Subexpr (N))),
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd => New_Occurrence_Of (Tnn, Loc),
Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
Reason => Reason)));
Rewrite (N, New_Occurrence_Of (Tnn, Loc));
end;
-- At this stage, we know that we have two scalar types, which are
-- directly convertible, and where neither scalar type has a base
-- range that is in the range of the other scalar type.
-- The only way this can happen is with a signed and unsigned type.
-- So test for these two cases:
else
-- Case of the source is unsigned and the target is signed
if Is_Unsigned_Type (Source_Base_Type)
and then not Is_Unsigned_Type (Target_Base_Type)
then
-- If the source is unsigned and the target is signed, then we
-- know that the source is not shorter than the target (otherwise
-- the source base type would be in the target base type range).
-- In other words, the unsigned type is either the same size
-- as the target, or it is larger. It cannot be smaller.
pragma Assert
(Esize (Source_Base_Type) >= Esize (Target_Base_Type));
-- We only need to check the low bound if the low bound of the
-- target type is non-negative. If the low bound of the target
-- type is negative, then we know that we will fit fine.
-- If the high bound of the target type is negative, then we
-- know we have a constraint error, since we can't possibly
-- have a negative source.
-- With these two checks out of the way, we can do the check
-- using the source type safely
-- This is definitely the most annoying case!
-- [constraint_error
-- when (Target_Type'First >= 0
-- and then
-- N < Source_Base_Type (Target_Type'First))
-- or else Target_Type'Last < 0
-- or else N > Source_Base_Type (Target_Type'Last)];
-- We turn off all checks since we know that the conversions
-- will work fine, given the guards for negative values.
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Or_Else (Loc,
Make_Or_Else (Loc,
Left_Opnd =>
Make_And_Then (Loc,
Left_Opnd => Make_Op_Ge (Loc,
Left_Opnd =>
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_First),
Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
Right_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd =>
Convert_To (Source_Base_Type,
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_First)))),
Right_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_Last),
Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
Right_Opnd =>
Make_Op_Gt (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd =>
Convert_To (Source_Base_Type,
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_Last)))),
Reason => Reason),
Suppress => All_Checks);
-- Only remaining possibility is that the source is signed and
-- the target is unsigned
else
pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
and then Is_Unsigned_Type (Target_Base_Type));
-- If the source is signed and the target is unsigned, then
-- we know that the target is not shorter than the source
-- (otherwise the target base type would be in the source
-- base type range).
-- In other words, the unsigned type is either the same size
-- as the target, or it is larger. It cannot be smaller.
-- Clearly we have an error if the source value is negative
-- since no unsigned type can have negative values. If the
-- source type is non-negative, then the check can be done
-- using the target type.
-- Tnn : constant Target_Base_Type (N) := Target_Type;
-- [constraint_error
-- when N < 0 or else Tnn not in Target_Type];
-- We turn off all checks for the conversion of N to the
-- target base type, since we generate the explicit check
-- to ensure that the value is non-negative
declare
Tnn : constant Entity_Id :=
Make_Defining_Identifier (Loc,
Chars => New_Internal_Name ('T'));
begin
Insert_Actions (N, New_List (
Make_Object_Declaration (Loc,
Defining_Identifier => Tnn,
Object_Definition =>
New_Occurrence_Of (Target_Base_Type, Loc),
Constant_Present => True,
Expression =>
Make_Type_Conversion (Loc,
Subtype_Mark =>
New_Occurrence_Of (Target_Base_Type, Loc),
Expression => Duplicate_Subexpr (N))),
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Or_Else (Loc,
Left_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
Right_Opnd =>
Make_Not_In (Loc,
Left_Opnd => New_Occurrence_Of (Tnn, Loc),
Right_Opnd =>
New_Occurrence_Of (Target_Type, Loc))),
Reason => Reason)),
Suppress => All_Checks);
-- Set the Etype explicitly, because Insert_Actions may
-- have placed the declaration in the freeze list for an
-- enclosing construct, and thus it is not analyzed yet.
Set_Etype (Tnn, Target_Base_Type);
Rewrite (N, New_Occurrence_Of (Tnn, Loc));
end;
end if;
end if;
end Generate_Range_Check;
---------------------
-- Get_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_No_Checks (Ck_Node),
Right_Opnd => Make_Null (Loc)),
Right_Opnd => Cond);
end if;
end Guard_Access;
-----------------------------
-- Index_Checks_Suppressed --
-----------------------------
function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Index_Check);
else
return Scope_Suppress (Index_Check);
end if;
end Index_Checks_Suppressed;
----------------
-- Initialize --
----------------
procedure Initialize is
begin
for J in Determine_Range_Cache_N'Range loop
Determine_Range_Cache_N (J) := Empty;
end loop;
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,
Reason => CE_Range_Check_Failed);
Mark_Rewrite_Insertion (Check_Node);
if Do_Before then
Insert_Before_And_Analyze (Node, Check_Node);
else
Insert_After_And_Analyze (Node, Check_Node);
end if;
end if;
end loop;
end Insert_Range_Checks;
------------------------
-- Insert_Valid_Check --
------------------------
procedure Insert_Valid_Check (Expr : Node_Id) is
Loc : constant Source_Ptr := Sloc (Expr);
Exp : Node_Id;
begin
-- Do not insert if checks off, or if not checking validity
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_No_Checks (Exp, Name_Req => True),
Attribute_Name => Name_Valid)),
Reason => CE_Invalid_Data),
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,
Reason => CE_Range_Check_Failed));
Set_Analyzed (R_Cno);
Set_Etype (R_Cno, Typ);
Set_Raises_Constraint_Error (R_Cno);
Set_Is_Static_Expression (R_Cno, Stat);
end Install_Static_Check;
---------------------
-- Kill_All_Checks --
---------------------
procedure Kill_All_Checks is
begin
if Debug_Flag_CC then
w ("Kill_All_Checks");
end if;
-- We reset the number of saved checks to zero, and also modify
-- all stack entries for statement ranges to indicate that the
-- number of checks at each level is now zero.
Num_Saved_Checks := 0;
for J in 1 .. Saved_Checks_TOS loop
Saved_Checks_Stack (J) := 0;
end loop;
end Kill_All_Checks;
-----------------
-- Kill_Checks --
-----------------
procedure Kill_Checks (V : Entity_Id) is
begin
if Debug_Flag_CC then
w ("Kill_Checks for entity", Int (V));
end if;
for J in 1 .. Num_Saved_Checks loop
if Saved_Checks (J).Entity = V then
if Debug_Flag_CC then
w (" Checks killed for saved check ", J);
end if;
Saved_Checks (J).Killed := True;
end if;
end loop;
end Kill_Checks;
------------------------------
-- Length_Checks_Suppressed --
------------------------------
function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Length_Check);
else
return Scope_Suppress (Length_Check);
end if;
end Length_Checks_Suppressed;
--------------------------------
-- Overflow_Checks_Suppressed --
--------------------------------
function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Overflow_Check);
else
return Scope_Suppress (Overflow_Check);
end if;
end Overflow_Checks_Suppressed;
-----------------
-- Range_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
if Present (E) then
-- Note: for now we always suppress range checks on Vax float types,
-- since Gigi does not know how to generate these checks.
if Vax_Float (E) then
return True;
elsif Kill_Range_Checks (E) then
return True;
elsif Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Range_Check);
end if;
end if;
return Scope_Suppress (Range_Check);
end Range_Checks_Suppressed;
-------------------
-- Remove_Checks --
-------------------
procedure Remove_Checks (Expr : Node_Id) is
Discard : Traverse_Result;
pragma Warnings (Off, Discard);
function Process (N : Node_Id) return Traverse_Result;
-- Process a single node during the traversal
function Traverse is new Traverse_Func (Process);
-- The traversal function itself