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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- C H E C K S --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2013, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Atree; use Atree;
with Debug; use Debug;
with Einfo; use Einfo;
with Errout; use Errout;
with Exp_Ch2; use Exp_Ch2;
with Exp_Ch4; use Exp_Ch4;
with Exp_Ch11; use Exp_Ch11;
with Exp_Pakd; use Exp_Pakd;
with Exp_Tss; use Exp_Tss;
with Exp_Util; use Exp_Util;
with Elists; use Elists;
with Expander; use Expander;
with Eval_Fat; use Eval_Fat;
with Freeze; use Freeze;
with Lib; use Lib;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Output; use Output;
with Restrict; use Restrict;
with Rident; use Rident;
with Rtsfind; use Rtsfind;
with Sem; use Sem;
with Sem_Aux; use Sem_Aux;
with Sem_Eval; use Sem_Eval;
with Sem_Ch3; use Sem_Ch3;
with Sem_Ch8; use Sem_Ch8;
with Sem_Res; use Sem_Res;
with Sem_Util; use Sem_Util;
with Sem_Warn; use Sem_Warn;
with Sinfo; use Sinfo;
with Sinput; use Sinput;
with Snames; use Snames;
with Sprint; use Sprint;
with Stand; use Stand;
with Targparm; use Targparm;
with Tbuild; use Tbuild;
with Ttypes; use Ttypes;
with Urealp; use Urealp;
with Validsw; use Validsw;
package body Checks is
-- General note: many of these routines are concerned with generating
-- checking code to make sure that constraint error is raised at runtime.
-- Clearly this code is only needed if the expander is active, since
-- otherwise we will not be generating code or going into the runtime
-- execution anyway.
-- We therefore disconnect most of these checks if the expander is
-- inactive. This has the additional benefit that we do not need to
-- worry about the tree being messed up by previous errors (since errors
-- turn off expansion anyway).
-- There are a few exceptions to the above rule. For instance routines
-- such as Apply_Scalar_Range_Check that do not insert any code can be
-- safely called even when the Expander is inactive (but Errors_Detected
-- is 0). The benefit of executing this code when expansion is off, is
-- the ability to emit constraint error warning for static expressions
-- even when we are not generating code.
-------------------------------------
-- Suppression of Redundant Checks --
-------------------------------------
-- This unit implements a limited circuit for removal of redundant
-- checks. The processing is based on a tracing of simple sequential
-- flow. For any sequence of statements, we save expressions that are
-- marked to be checked, and then if the same expression appears later
-- with the same check, then under certain circumstances, the second
-- check can be suppressed.
-- Basically, we can suppress the check if we know for certain that
-- the previous expression has been elaborated (together with its
-- check), and we know that the exception frame is the same, and that
-- nothing has happened to change the result of the exception.
-- Let us examine each of these three conditions in turn to describe
-- how we ensure that this condition is met.
-- First, we need to know for certain that the previous expression has
-- been executed. This is done principally by the mechanism of calling
-- Conditional_Statements_Begin at the start of any statement sequence
-- and Conditional_Statements_End at the end. The End call causes all
-- checks remembered since the Begin call to be discarded. This does
-- miss a few cases, notably the case of a nested BEGIN-END block with
-- no exception handlers. But the important thing is to be conservative.
-- The other protection is that all checks are discarded if a label
-- is encountered, since then the assumption of sequential execution
-- is violated, and we don't know enough about the flow.
-- Second, we need to know that the exception frame is the same. We
-- do this by killing all remembered checks when we enter a new frame.
-- Again, that's over-conservative, but generally the cases we can help
-- with are pretty local anyway (like the body of a loop for example).
-- Third, we must be sure to forget any checks which are no longer valid.
-- This is done by two mechanisms, first the Kill_Checks_Variable call is
-- used to note any changes to local variables. We only attempt to deal
-- with checks involving local variables, so we do not need to worry
-- about global variables. Second, a call to any non-global procedure
-- causes us to abandon all stored checks, since such a all may affect
-- the values of any local variables.
-- The following define the data structures used to deal with remembering
-- checks so that redundant checks can be eliminated as described above.
-- Right now, the only expressions that we deal with are of the form of
-- simple local objects (either declared locally, or IN parameters) or
-- such objects plus/minus a compile time known constant. We can do
-- more later on if it seems worthwhile, but this catches many simple
-- cases in practice.
-- The following record type reflects a single saved check. An entry
-- is made in the stack of saved checks if and only if the expression
-- has been elaborated with the indicated checks.
type Saved_Check is record
Killed : Boolean;
-- Set True if entry is killed by Kill_Checks
Entity : Entity_Id;
-- The entity involved in the expression that is checked
Offset : Uint;
-- A compile time value indicating the result of adding or
-- subtracting a compile time value. This value is to be
-- added to the value of the Entity. A value of zero is
-- used for the case of a simple entity reference.
Check_Type : Character;
-- This is set to 'R' for a range check (in which case Target_Type
-- is set to the target type for the range check) or to 'O' for an
-- overflow check (in which case Target_Type is set to Empty).
Target_Type : Entity_Id;
-- Used only if Do_Range_Check is set. Records the target type for
-- the check. We need this, because a check is a duplicate only if
-- it has the same target type (or more accurately one with a
-- range that is smaller or equal to the stored target type of a
-- saved check).
end record;
-- The following table keeps track of saved checks. Rather than use an
-- extensible table. We just use a table of fixed size, and we discard
-- any saved checks that do not fit. That's very unlikely to happen and
-- this is only an optimization in any case.
Saved_Checks : array (Int range 1 .. 200) of Saved_Check;
-- Array of saved checks
Num_Saved_Checks : Nat := 0;
-- Number of saved checks
-- The following stack keeps track of statement ranges. It is treated
-- as a stack. When Conditional_Statements_Begin is called, an entry
-- is pushed onto this stack containing the value of Num_Saved_Checks
-- at the time of the call. Then when Conditional_Statements_End is
-- called, this value is popped off and used to reset Num_Saved_Checks.
-- Note: again, this is a fixed length stack with a size that should
-- always be fine. If the value of the stack pointer goes above the
-- limit, then we just forget all saved checks.
Saved_Checks_Stack : array (Int range 1 .. 100) of Nat;
Saved_Checks_TOS : Nat := 0;
-----------------------
-- Local Subprograms --
-----------------------
procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id);
-- Used to apply arithmetic overflow checks for all cases except operators
-- on signed arithmetic types in MINIMIZED/ELIMINATED case (for which we
-- call Apply_Arithmetic_Overflow_Minimized_Eliminated below). N can be a
-- signed integer arithmetic operator (but not an if or case expression).
-- It is also called for types other than signed integers.
procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id);
-- Used to apply arithmetic overflow checks for the case where the overflow
-- checking mode is MINIMIZED or ELIMINATED and we have a signed integer
-- arithmetic op (which includes the case of if and case expressions). Note
-- that Do_Overflow_Check may or may not be set for node Op. In these modes
-- we have work to do even if overflow checking is suppressed.
procedure Apply_Division_Check
(N : Node_Id;
Rlo : Uint;
Rhi : Uint;
ROK : Boolean);
-- N is an N_Op_Div, N_Op_Rem, or N_Op_Mod node. This routine applies
-- division checks as required if the Do_Division_Check flag is set.
-- Rlo and Rhi give the possible range of the right operand, these values
-- can be referenced and trusted only if ROK is set True.
procedure Apply_Float_Conversion_Check
(Ck_Node : Node_Id;
Target_Typ : Entity_Id);
-- The checks on a conversion from a floating-point type to an integer
-- type are delicate. They have to be performed before conversion, they
-- have to raise an exception when the operand is a NaN, and rounding must
-- be taken into account to determine the safe bounds of the operand.
procedure Apply_Selected_Length_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Do_Static : Boolean);
-- This is the subprogram that does all the work for Apply_Length_Check
-- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
-- described for the above routines. The Do_Static flag indicates that
-- only a static check is to be done.
procedure Apply_Selected_Range_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Do_Static : Boolean);
-- This is the subprogram that does all the work for Apply_Range_Check.
-- Expr, Target_Typ and Source_Typ are as described for the above
-- routine. The Do_Static flag indicates that only a static check is
-- to be done.
type Check_Type is new Check_Id range Access_Check .. Division_Check;
function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean;
-- This function is used to see if an access or division by zero check is
-- needed. The check is to be applied to a single variable appearing in the
-- source, and N is the node for the reference. If N is not of this form,
-- True is returned with no further processing. If N is of the right form,
-- then further processing determines if the given Check is needed.
--
-- The particular circuit is to see if we have the case of a check that is
-- not needed because it appears in the right operand of a short circuited
-- conditional where the left operand guards the check. For example:
--
-- if Var = 0 or else Q / Var > 12 then
-- ...
-- end if;
--
-- In this example, the division check is not required. At the same time
-- we can issue warnings for suspicious use of non-short-circuited forms,
-- such as:
--
-- if Var = 0 or Q / Var > 12 then
-- ...
-- end if;
procedure Find_Check
(Expr : Node_Id;
Check_Type : Character;
Target_Type : Entity_Id;
Entry_OK : out Boolean;
Check_Num : out Nat;
Ent : out Entity_Id;
Ofs : out Uint);
-- This routine is used by Enable_Range_Check and Enable_Overflow_Check
-- to see if a check is of the form for optimization, and if so, to see
-- if it has already been performed. Expr is the expression to check,
-- and Check_Type is 'R' for a range check, 'O' for an overflow check.
-- Target_Type is the target type for a range check, and Empty for an
-- overflow check. If the entry is not of the form for optimization,
-- then Entry_OK is set to False, and the remaining out parameters
-- are undefined. If the entry is OK, then Ent/Ofs are set to the
-- entity and offset from the expression. Check_Num is the number of
-- a matching saved entry in Saved_Checks, or zero if no such entry
-- is located.
function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id;
-- If a discriminal is used in constraining a prival, Return reference
-- to the discriminal of the protected body (which renames the parameter
-- of the enclosing protected operation). This clumsy transformation is
-- needed because privals are created too late and their actual subtypes
-- are not available when analysing the bodies of the protected operations.
-- This function is called whenever the bound is an entity and the scope
-- indicates a protected operation. If the bound is an in-parameter of
-- a protected operation that is not a prival, the function returns the
-- bound itself.
-- To be cleaned up???
function Guard_Access
(Cond : Node_Id;
Loc : Source_Ptr;
Ck_Node : Node_Id) return Node_Id;
-- In the access type case, guard the test with a test to ensure
-- that the access value is non-null, since the checks do not
-- not apply to null access values.
procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr);
-- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
-- Constraint_Error node.
function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean;
-- Returns True if node N is for an arithmetic operation with signed
-- integer operands. This includes unary and binary operators, and also
-- if and case expression nodes where the dependent expressions are of
-- a signed integer type. These are the kinds of nodes for which special
-- handling applies in MINIMIZED or ELIMINATED overflow checking mode.
function Range_Or_Validity_Checks_Suppressed
(Expr : Node_Id) return Boolean;
-- Returns True if either range or validity checks or both are suppressed
-- for the type of the given expression, or, if the expression is the name
-- of an entity, if these checks are suppressed for the entity.
function Selected_Length_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Warn_Node : Node_Id) return Check_Result;
-- Like Apply_Selected_Length_Checks, except it doesn't modify
-- anything, just returns a list of nodes as described in the spec of
-- this package for the Range_Check function.
function Selected_Range_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Warn_Node : Node_Id) return Check_Result;
-- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
-- just returns a list of nodes as described in the spec of this package
-- for the Range_Check function.
------------------------------
-- Access_Checks_Suppressed --
------------------------------
function Access_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Access_Check);
else
return Scope_Suppress.Suppress (Access_Check);
end if;
end Access_Checks_Suppressed;
-------------------------------------
-- Accessibility_Checks_Suppressed --
-------------------------------------
function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Accessibility_Check);
else
return Scope_Suppress.Suppress (Accessibility_Check);
end if;
end Accessibility_Checks_Suppressed;
-----------------------------
-- Activate_Division_Check --
-----------------------------
procedure Activate_Division_Check (N : Node_Id) is
begin
Set_Do_Division_Check (N, True);
Possible_Local_Raise (N, Standard_Constraint_Error);
end Activate_Division_Check;
-----------------------------
-- Activate_Overflow_Check --
-----------------------------
procedure Activate_Overflow_Check (N : Node_Id) is
begin
if not Nkind_In (N, N_Op_Rem, N_Op_Mod, N_Op_Plus) then
Set_Do_Overflow_Check (N, True);
Possible_Local_Raise (N, Standard_Constraint_Error);
end if;
end Activate_Overflow_Check;
--------------------------
-- Activate_Range_Check --
--------------------------
procedure Activate_Range_Check (N : Node_Id) is
begin
Set_Do_Range_Check (N, True);
Possible_Local_Raise (N, Standard_Constraint_Error);
end Activate_Range_Check;
---------------------------------
-- Alignment_Checks_Suppressed --
---------------------------------
function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Alignment_Check);
else
return Scope_Suppress.Suppress (Alignment_Check);
end if;
end Alignment_Checks_Suppressed;
-------------------------
-- Append_Range_Checks --
-------------------------
procedure Append_Range_Checks
(Checks : Check_Result;
Stmts : List_Id;
Suppress_Typ : Entity_Id;
Static_Sloc : Source_Ptr;
Flag_Node : Node_Id)
is
Internal_Flag_Node : constant Node_Id := Flag_Node;
Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
Checks_On : constant Boolean :=
(not Index_Checks_Suppressed (Suppress_Typ))
or else (not Range_Checks_Suppressed (Suppress_Typ));
begin
-- For now we just return if Checks_On is false, however this should
-- be enhanced to check for an always True value in the condition
-- and to generate a compilation warning???
if not Checks_On then
return;
end if;
for J in 1 .. 2 loop
exit when No (Checks (J));
if Nkind (Checks (J)) = N_Raise_Constraint_Error
and then Present (Condition (Checks (J)))
then
if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
Append_To (Stmts, Checks (J));
Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
end if;
else
Append_To
(Stmts,
Make_Raise_Constraint_Error (Internal_Static_Sloc,
Reason => CE_Range_Check_Failed));
end if;
end loop;
end Append_Range_Checks;
------------------------
-- Apply_Access_Check --
------------------------
procedure Apply_Access_Check (N : Node_Id) is
P : constant Node_Id := Prefix (N);
begin
-- We do not need checks if we are not generating code (i.e. the
-- expander is not active). This is not just an optimization, there
-- are cases (e.g. with pragma Debug) where generating the checks
-- can cause real trouble).
if not Full_Expander_Active then
return;
end if;
-- No check if short circuiting makes check unnecessary
if not Check_Needed (P, Access_Check) then
return;
end if;
-- No check if accessing the Offset_To_Top component of a dispatch
-- table. They are safe by construction.
if Tagged_Type_Expansion
and then Present (Etype (P))
and then RTU_Loaded (Ada_Tags)
and then RTE_Available (RE_Offset_To_Top_Ptr)
and then Etype (P) = RTE (RE_Offset_To_Top_Ptr)
then
return;
end if;
-- Otherwise go ahead and install the check
Install_Null_Excluding_Check (P);
end Apply_Access_Check;
-------------------------------
-- Apply_Accessibility_Check --
-------------------------------
procedure Apply_Accessibility_Check
(N : Node_Id;
Typ : Entity_Id;
Insert_Node : Node_Id)
is
Loc : constant Source_Ptr := Sloc (N);
Param_Ent : Entity_Id := Param_Entity (N);
Param_Level : Node_Id;
Type_Level : Node_Id;
begin
if Ada_Version >= Ada_2012
and then not Present (Param_Ent)
and then Is_Entity_Name (N)
and then Ekind_In (Entity (N), E_Constant, E_Variable)
and then Present (Effective_Extra_Accessibility (Entity (N)))
then
Param_Ent := Entity (N);
while Present (Renamed_Object (Param_Ent)) loop
-- Renamed_Object must return an Entity_Name here
-- because of preceding "Present (E_E_A (...))" test.
Param_Ent := Entity (Renamed_Object (Param_Ent));
end loop;
end if;
if Inside_A_Generic then
return;
-- Only apply the run-time check if the access parameter has an
-- associated extra access level parameter and when the level of the
-- type is less deep than the level of the access parameter, and
-- accessibility checks are not suppressed.
elsif Present (Param_Ent)
and then Present (Extra_Accessibility (Param_Ent))
and then UI_Gt (Object_Access_Level (N),
Deepest_Type_Access_Level (Typ))
and then not Accessibility_Checks_Suppressed (Param_Ent)
and then not Accessibility_Checks_Suppressed (Typ)
then
Param_Level :=
New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
Type_Level :=
Make_Integer_Literal (Loc, Deepest_Type_Access_Level (Typ));
-- Raise Program_Error if the accessibility level of the access
-- parameter is deeper than the level of the target access type.
Insert_Action (Insert_Node,
Make_Raise_Program_Error (Loc,
Condition =>
Make_Op_Gt (Loc,
Left_Opnd => Param_Level,
Right_Opnd => Type_Level),
Reason => PE_Accessibility_Check_Failed));
Analyze_And_Resolve (N);
end if;
end Apply_Accessibility_Check;
--------------------------------
-- Apply_Address_Clause_Check --
--------------------------------
procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
pragma Assert (Nkind (N) = N_Freeze_Entity);
AC : constant Node_Id := Address_Clause (E);
Loc : constant Source_Ptr := Sloc (AC);
Typ : constant Entity_Id := Etype (E);
Aexp : constant Node_Id := Expression (AC);
Expr : Node_Id;
-- Address expression (not necessarily the same as Aexp, for example
-- when Aexp is a reference to a constant, in which case Expr gets
-- reset to reference the value expression of the constant.
procedure Compile_Time_Bad_Alignment;
-- Post error warnings when alignment is known to be incompatible. Note
-- that we do not go as far as inserting a raise of Program_Error since
-- this is an erroneous case, and it may happen that we are lucky and an
-- underaligned address turns out to be OK after all.
--------------------------------
-- Compile_Time_Bad_Alignment --
--------------------------------
procedure Compile_Time_Bad_Alignment is
begin
if Address_Clause_Overlay_Warnings then
Error_Msg_FE
("?o?specified address for& may be inconsistent with alignment",
Aexp, E);
Error_Msg_FE
("\?o?program execution may be erroneous (RM 13.3(27))",
Aexp, E);
Set_Address_Warning_Posted (AC);
end if;
end Compile_Time_Bad_Alignment;
-- Start of processing for Apply_Address_Clause_Check
begin
-- See if alignment check needed. Note that we never need a check if the
-- maximum alignment is one, since the check will always succeed.
-- Note: we do not check for checks suppressed here, since that check
-- was done in Sem_Ch13 when the address clause was processed. We are
-- only called if checks were not suppressed. The reason for this is
-- that we have to delay the call to Apply_Alignment_Check till freeze
-- time (so that all types etc are elaborated), but we have to check
-- the status of check suppressing at the point of the address clause.
if No (AC)
or else not Check_Address_Alignment (AC)
or else Maximum_Alignment = 1
then
return;
end if;
-- Obtain expression from address clause
Expr := Expression (AC);
-- The following loop digs for the real expression to use in the check
loop
-- For constant, get constant expression
if Is_Entity_Name (Expr)
and then Ekind (Entity (Expr)) = E_Constant
then
Expr := Constant_Value (Entity (Expr));
-- For unchecked conversion, get result to convert
elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
Expr := Expression (Expr);
-- For (common case) of To_Address call, get argument
elsif Nkind (Expr) = N_Function_Call
and then Is_Entity_Name (Name (Expr))
and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
then
Expr := First (Parameter_Associations (Expr));
if Nkind (Expr) = N_Parameter_Association then
Expr := Explicit_Actual_Parameter (Expr);
end if;
-- We finally have the real expression
else
exit;
end if;
end loop;
-- See if we know that Expr has a bad alignment at compile time
if Compile_Time_Known_Value (Expr)
and then (Known_Alignment (E) or else Known_Alignment (Typ))
then
declare
AL : Uint := Alignment (Typ);
begin
-- The object alignment might be more restrictive than the
-- type alignment.
if Known_Alignment (E) then
AL := Alignment (E);
end if;
if Expr_Value (Expr) mod AL /= 0 then
Compile_Time_Bad_Alignment;
else
return;
end if;
end;
-- If the expression has the form X'Address, then we can find out if
-- the object X has an alignment that is compatible with the object E.
-- If it hasn't or we don't know, we defer issuing the warning until
-- the end of the compilation to take into account back end annotations.
elsif Nkind (Expr) = N_Attribute_Reference
and then Attribute_Name (Expr) = Name_Address
and then Has_Compatible_Alignment (E, Prefix (Expr)) = Known_Compatible
then
return;
end if;
-- Here we do not know if the value is acceptable. Strictly we don't
-- have to do anything, since if the alignment is bad, we have an
-- erroneous program. However we are allowed to check for erroneous
-- conditions and we decide to do this by default if the check is not
-- suppressed.
-- However, don't do the check if elaboration code is unwanted
if Restriction_Active (No_Elaboration_Code) then
return;
-- Generate a check to raise PE if alignment may be inappropriate
else
-- If the original expression is a non-static constant, use the
-- name of the constant itself rather than duplicating its
-- defining expression, which was extracted above.
-- Note: Expr is empty if the address-clause is applied to in-mode
-- actuals (allowed by 13.1(22)).
if not Present (Expr)
or else
(Is_Entity_Name (Expression (AC))
and then Ekind (Entity (Expression (AC))) = E_Constant
and then Nkind (Parent (Entity (Expression (AC))))
= N_Object_Declaration)
then
Expr := New_Copy_Tree (Expression (AC));
else
Remove_Side_Effects (Expr);
end if;
if No (Actions (N)) then
Set_Actions (N, New_List);
end if;
Prepend_To (Actions (N),
Make_Raise_Program_Error (Loc,
Condition =>
Make_Op_Ne (Loc,
Left_Opnd =>
Make_Op_Mod (Loc,
Left_Opnd =>
Unchecked_Convert_To
(RTE (RE_Integer_Address), Expr),
Right_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (E, Loc),
Attribute_Name => Name_Alignment)),
Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
Reason => PE_Misaligned_Address_Value));
Analyze (First (Actions (N)), Suppress => All_Checks);
return;
end if;
exception
-- If we have some missing run time component in configurable run time
-- mode then just skip the check (it is not required in any case).
when RE_Not_Available =>
return;
end Apply_Address_Clause_Check;
-------------------------------------
-- Apply_Arithmetic_Overflow_Check --
-------------------------------------
procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
begin
-- Use old routine in almost all cases (the only case we are treating
-- specially is the case of a signed integer arithmetic op with the
-- overflow checking mode set to MINIMIZED or ELIMINATED).
if Overflow_Check_Mode = Strict
or else not Is_Signed_Integer_Arithmetic_Op (N)
then
Apply_Arithmetic_Overflow_Strict (N);
-- Otherwise use the new routine for the case of a signed integer
-- arithmetic op, with Do_Overflow_Check set to True, and the checking
-- mode is MINIMIZED or ELIMINATED.
else
Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
end if;
end Apply_Arithmetic_Overflow_Check;
--------------------------------------
-- Apply_Arithmetic_Overflow_Strict --
--------------------------------------
-- This routine is called only if the type is an integer type, and a
-- software arithmetic overflow check may be needed for op (add, subtract,
-- or multiply). This check is performed only if Software_Overflow_Checking
-- is enabled and Do_Overflow_Check is set. In this case we expand the
-- operation into a more complex sequence of tests that ensures that
-- overflow is properly caught.
-- This is used in CHECKED modes. It is identical to the code for this
-- cases before the big overflow earthquake, thus ensuring that in this
-- modes we have compatible behavior (and reliability) to what was there
-- before. It is also called for types other than signed integers, and if
-- the Do_Overflow_Check flag is off.
-- Note: we also call this routine if we decide in the MINIMIZED case
-- to give up and just generate an overflow check without any fuss.
procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
Rtyp : constant Entity_Id := Root_Type (Typ);
begin
-- Nothing to do if Do_Overflow_Check not set or overflow checks
-- suppressed.
if not Do_Overflow_Check (N) then
return;
end if;
-- An interesting special case. If the arithmetic operation appears as
-- the operand of a type conversion:
-- type1 (x op y)
-- and all the following conditions apply:
-- arithmetic operation is for a signed integer type
-- target type type1 is a static integer subtype
-- range of x and y are both included in the range of type1
-- range of x op y is included in the range of type1
-- size of type1 is at least twice the result size of op
-- then we don't do an overflow check in any case, instead we transform
-- the operation so that we end up with:
-- type1 (type1 (x) op type1 (y))
-- This avoids intermediate overflow before the conversion. It is
-- explicitly permitted by RM 3.5.4(24):
-- For the execution of a predefined operation of a signed integer
-- type, the implementation need not raise Constraint_Error if the
-- result is outside the base range of the type, so long as the
-- correct result is produced.
-- It's hard to imagine that any programmer counts on the exception
-- being raised in this case, and in any case it's wrong coding to
-- have this expectation, given the RM permission. Furthermore, other
-- Ada compilers do allow such out of range results.
-- Note that we do this transformation even if overflow checking is
-- off, since this is precisely about giving the "right" result and
-- avoiding the need for an overflow check.
-- Note: this circuit is partially redundant with respect to the similar
-- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
-- with cases that do not come through here. We still need the following
-- processing even with the Exp_Ch4 code in place, since we want to be
-- sure not to generate the arithmetic overflow check in these cases
-- (Exp_Ch4 would have a hard time removing them once generated).
if Is_Signed_Integer_Type (Typ)
and then Nkind (Parent (N)) = N_Type_Conversion
then
Conversion_Optimization : declare
Target_Type : constant Entity_Id :=
Base_Type (Entity (Subtype_Mark (Parent (N))));
Llo, Lhi : Uint;
Rlo, Rhi : Uint;
LOK, ROK : Boolean;
Vlo : Uint;
Vhi : Uint;
VOK : Boolean;
Tlo : Uint;
Thi : Uint;
begin
if Is_Integer_Type (Target_Type)
and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
then
Tlo := Expr_Value (Type_Low_Bound (Target_Type));
Thi := Expr_Value (Type_High_Bound (Target_Type));
Determine_Range
(Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
Determine_Range
(Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
if (LOK and ROK)
and then Tlo <= Llo and then Lhi <= Thi
and then Tlo <= Rlo and then Rhi <= Thi
then
Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
if VOK and then Tlo <= Vlo and then Vhi <= Thi then
Rewrite (Left_Opnd (N),
Make_Type_Conversion (Loc,
Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
Expression => Relocate_Node (Left_Opnd (N))));
Rewrite (Right_Opnd (N),
Make_Type_Conversion (Loc,
Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
Expression => Relocate_Node (Right_Opnd (N))));
-- Rewrite the conversion operand so that the original
-- node is retained, in order to avoid the warning for
-- redundant conversions in Resolve_Type_Conversion.
Rewrite (N, Relocate_Node (N));
Set_Etype (N, Target_Type);
Analyze_And_Resolve (Left_Opnd (N), Target_Type);
Analyze_And_Resolve (Right_Opnd (N), Target_Type);
-- Given that the target type is twice the size of the
-- source type, overflow is now impossible, so we can
-- safely kill the overflow check and return.
Set_Do_Overflow_Check (N, False);
return;
end if;
end if;
end if;
end Conversion_Optimization;
end if;
-- Now see if an overflow check is required
declare
Siz : constant Int := UI_To_Int (Esize (Rtyp));
Dsiz : constant Int := Siz * 2;
Opnod : Node_Id;
Ctyp : Entity_Id;
Opnd : Node_Id;
Cent : RE_Id;
begin
-- Skip check if back end does overflow checks, or the overflow flag
-- is not set anyway, or we are not doing code expansion, or the
-- parent node is a type conversion whose operand is an arithmetic
-- operation on signed integers on which the expander can promote
-- later the operands to type Integer (see Expand_N_Type_Conversion).
-- Special case CLI target, where arithmetic overflow checks can be
-- performed for integer and long_integer
if Backend_Overflow_Checks_On_Target
or else not Do_Overflow_Check (N)
or else not Full_Expander_Active
or else (Present (Parent (N))
and then Nkind (Parent (N)) = N_Type_Conversion
and then Integer_Promotion_Possible (Parent (N)))
or else
(VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
then
return;
end if;
-- Otherwise, generate the full general code for front end overflow
-- detection, which works by doing arithmetic in a larger type:
-- x op y
-- is expanded into
-- Typ (Checktyp (x) op Checktyp (y));
-- where Typ is the type of the original expression, and Checktyp is
-- an integer type of sufficient length to hold the largest possible
-- result.
-- If the size of check type exceeds the size of Long_Long_Integer,
-- we use a different approach, expanding to:
-- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
-- where xxx is Add, Multiply or Subtract as appropriate
-- Find check type if one exists
if Dsiz <= Standard_Integer_Size then
Ctyp := Standard_Integer;
elsif Dsiz <= Standard_Long_Long_Integer_Size then
Ctyp := Standard_Long_Long_Integer;
-- No check type exists, use runtime call
else
if Nkind (N) = N_Op_Add then
Cent := RE_Add_With_Ovflo_Check;
elsif Nkind (N) = N_Op_Multiply then
Cent := RE_Multiply_With_Ovflo_Check;
else
pragma Assert (Nkind (N) = N_Op_Subtract);
Cent := RE_Subtract_With_Ovflo_Check;
end if;
Rewrite (N,
OK_Convert_To (Typ,
Make_Function_Call (Loc,
Name => New_Reference_To (RTE (Cent), Loc),
Parameter_Associations => New_List (
OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
Analyze_And_Resolve (N, Typ);
return;
end if;
-- If we fall through, we have the case where we do the arithmetic
-- in the next higher type and get the check by conversion. In these
-- cases Ctyp is set to the type to be used as the check type.
Opnod := Relocate_Node (N);
Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
Analyze (Opnd);
Set_Etype (Opnd, Ctyp);
Set_Analyzed (Opnd, True);
Set_Left_Opnd (Opnod, Opnd);
Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
Analyze (Opnd);
Set_Etype (Opnd, Ctyp);
Set_Analyzed (Opnd, True);
Set_Right_Opnd (Opnod, Opnd);
-- The type of the operation changes to the base type of the check
-- type, and we reset the overflow check indication, since clearly no
-- overflow is possible now that we are using a double length type.
-- We also set the Analyzed flag to avoid a recursive attempt to
-- expand the node.
Set_Etype (Opnod, Base_Type (Ctyp));
Set_Do_Overflow_Check (Opnod, False);
Set_Analyzed (Opnod, True);
-- Now build the outer conversion
Opnd := OK_Convert_To (Typ, Opnod);
Analyze (Opnd);
Set_Etype (Opnd, Typ);
-- In the discrete type case, we directly generate the range check
-- for the outer operand. This range check will implement the
-- required overflow check.
if Is_Discrete_Type (Typ) then
Rewrite (N, Opnd);
Generate_Range_Check
(Expression (N), Typ, CE_Overflow_Check_Failed);
-- For other types, we enable overflow checking on the conversion,
-- after setting the node as analyzed to prevent recursive attempts
-- to expand the conversion node.
else
Set_Analyzed (Opnd, True);
Enable_Overflow_Check (Opnd);
Rewrite (N, Opnd);
end if;
exception
when RE_Not_Available =>
return;
end;
end Apply_Arithmetic_Overflow_Strict;
----------------------------------------------------
-- Apply_Arithmetic_Overflow_Minimized_Eliminated --
----------------------------------------------------
procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id) is
pragma Assert (Is_Signed_Integer_Arithmetic_Op (Op));
Loc : constant Source_Ptr := Sloc (Op);
P : constant Node_Id := Parent (Op);
LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
-- Operands and results are of this type when we convert
Result_Type : constant Entity_Id := Etype (Op);
-- Original result type
Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
pragma Assert (Check_Mode in Minimized_Or_Eliminated);
Lo, Hi : Uint;
-- Ranges of values for result
begin
-- Nothing to do if our parent is one of the following:
-- Another signed integer arithmetic op
-- A membership operation
-- A comparison operation
-- In all these cases, we will process at the higher level (and then
-- this node will be processed during the downwards recursion that
-- is part of the processing in Minimize_Eliminate_Overflows).
if Is_Signed_Integer_Arithmetic_Op (P)
or else Nkind (P) in N_Membership_Test
or else Nkind (P) in N_Op_Compare
-- This is also true for an alternative in a case expression
or else Nkind (P) = N_Case_Expression_Alternative
-- This is also true for a range operand in a membership test
or else (Nkind (P) = N_Range
and then Nkind (Parent (P)) in N_Membership_Test)
then
return;
end if;
-- Otherwise, we have a top level arithmetic operation node, and this
-- is where we commence the special processing for MINIMIZED/ELIMINATED
-- modes. This is the case where we tell the machinery not to move into
-- Bignum mode at this top level (of course the top level operation
-- will still be in Bignum mode if either of its operands are of type
-- Bignum).
Minimize_Eliminate_Overflows (Op, Lo, Hi, Top_Level => True);
-- That call may but does not necessarily change the result type of Op.
-- It is the job of this routine to undo such changes, so that at the
-- top level, we have the proper type. This "undoing" is a point at
-- which a final overflow check may be applied.
-- If the result type was not fiddled we are all set. We go to base
-- types here because things may have been rewritten to generate the
-- base type of the operand types.
if Base_Type (Etype (Op)) = Base_Type (Result_Type) then
return;
-- Bignum case
elsif Is_RTE (Etype (Op), RE_Bignum) then
-- We need a sequence that looks like:
-- Rnn : Result_Type;
-- declare
-- M : Mark_Id := SS_Mark;
-- begin
-- Rnn := Long_Long_Integer'Base (From_Bignum (Op));
-- SS_Release (M);
-- end;
-- This block is inserted (using Insert_Actions), and then the node
-- is replaced with a reference to Rnn.
-- A special case arises if our parent is a conversion node. In this
-- case no point in generating a conversion to Result_Type, we will
-- let the parent handle this. Note that this special case is not
-- just about optimization. Consider
-- A,B,C : Integer;
-- ...
-- X := Long_Long_Integer'Base (A * (B ** C));
-- Now the product may fit in Long_Long_Integer but not in Integer.
-- In MINIMIZED/ELIMINATED mode, we don't want to introduce an
-- overflow exception for this intermediate value.
declare
Blk : constant Node_Id := Make_Bignum_Block (Loc);
Rnn : constant Entity_Id := Make_Temporary (Loc, 'R', Op);
RHS : Node_Id;
Rtype : Entity_Id;
begin
RHS := Convert_From_Bignum (Op);
if Nkind (P) /= N_Type_Conversion then
Convert_To_And_Rewrite (Result_Type, RHS);
Rtype := Result_Type;
-- Interesting question, do we need a check on that conversion
-- operation. Answer, not if we know the result is in range.
-- At the moment we are not taking advantage of this. To be
-- looked at later ???
else
Rtype := LLIB;
end if;
Insert_Before
(First (Statements (Handled_Statement_Sequence (Blk))),
Make_Assignment_Statement (Loc,
Name => New_Occurrence_Of (Rnn, Loc),
Expression => RHS));
Insert_Actions (Op, New_List (
Make_Object_Declaration (Loc,
Defining_Identifier => Rnn,
Object_Definition => New_Occurrence_Of (Rtype, Loc)),
Blk));
Rewrite (Op, New_Occurrence_Of (Rnn, Loc));
Analyze_And_Resolve (Op);
end;
-- Here we know the result is Long_Long_Integer'Base, of that it has
-- been rewritten because the parent operation is a conversion. See
-- Apply_Arithmetic_Overflow_Strict.Conversion_Optimization.
else
pragma Assert
(Etype (Op) = LLIB or else Nkind (Parent (Op)) = N_Type_Conversion);
-- All we need to do here is to convert the result to the proper
-- result type. As explained above for the Bignum case, we can
-- omit this if our parent is a type conversion.
if Nkind (P) /= N_Type_Conversion then
Convert_To_And_Rewrite (Result_Type, Op);
end if;
Analyze_And_Resolve (Op);
end if;
end Apply_Arithmetic_Overflow_Minimized_Eliminated;
----------------------------
-- Apply_Constraint_Check --
----------------------------
procedure Apply_Constraint_Check
(N : Node_Id;
Typ : Entity_Id;
No_Sliding : Boolean := False)
is
Desig_Typ : Entity_Id;
begin
-- No checks inside a generic (check the instantiations)
if Inside_A_Generic then
return;
end if;
-- Apply required constraint checks
if Is_Scalar_Type (Typ) then
Apply_Scalar_Range_Check (N, Typ);
elsif Is_Array_Type (Typ) then
-- A useful optimization: an aggregate with only an others clause
-- always has the right bounds.
if Nkind (N) = N_Aggregate
and then No (Expressions (N))
and then Nkind
(First (Choices (First (Component_Associations (N)))))
= N_Others_Choice
then
return;
end if;
if Is_Constrained (Typ) then
Apply_Length_Check (N, Typ);
if No_Sliding then
Apply_Range_Check (N, Typ);
end if;
else
Apply_Range_Check (N, Typ);
end if;
elsif (Is_Record_Type (Typ) or else Is_Private_Type (Typ))
and then Has_Discriminants (Base_Type (Typ))
and then Is_Constrained (Typ)
then
Apply_Discriminant_Check (N, Typ);
elsif Is_Access_Type (Typ) then
Desig_Typ := Designated_Type (Typ);
-- No checks necessary if expression statically null
if Known_Null (N) then
if Can_Never_Be_Null (Typ) then
Install_Null_Excluding_Check (N);
end if;
-- No sliding possible on access to arrays
elsif Is_Array_Type (Desig_Typ) then
if Is_Constrained (Desig_Typ) then
Apply_Length_Check (N, Typ);
end if;
Apply_Range_Check (N, Typ);
elsif Has_Discriminants (Base_Type (Desig_Typ))
and then Is_Constrained (Desig_Typ)
then
Apply_Discriminant_Check (N, Typ);
end if;
-- Apply the 2005 Null_Excluding check. Note that we do not apply
-- this check if the constraint node is illegal, as shown by having
-- an error posted. This additional guard prevents cascaded errors
-- and compiler aborts on illegal programs involving Ada 2005 checks.
if Can_Never_Be_Null (Typ)
and then not Can_Never_Be_Null (Etype (N))
and then not Error_Posted (N)
then
Install_Null_Excluding_Check (N);
end if;
end if;
end Apply_Constraint_Check;
------------------------------
-- Apply_Discriminant_Check --
------------------------------
procedure Apply_Discriminant_Check
(N : Node_Id;
Typ : Entity_Id;
Lhs : Node_Id := Empty)
is
Loc : constant Source_Ptr := Sloc (N);
Do_Access : constant Boolean := Is_Access_Type (Typ);
S_Typ : Entity_Id := Etype (N);
Cond : Node_Id;
T_Typ : Entity_Id;
function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean;
-- A heap object with an indefinite subtype is constrained by its
-- initial value, and assigning to it requires a constraint_check.
-- The target may be an explicit dereference, or a renaming of one.
function Is_Aliased_Unconstrained_Component return Boolean;
-- It is possible for an aliased component to have a nominal
-- unconstrained subtype (through instantiation). If this is a
-- discriminated component assigned in the expansion of an aggregate
-- in an initialization, the check must be suppressed. This unusual
-- situation requires a predicate of its own.
----------------------------------
-- Denotes_Explicit_Dereference --
----------------------------------
function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is
begin
return
Nkind (Obj) = N_Explicit_Dereference
or else
(Is_Entity_Name (Obj)
and then Present (Renamed_Object (Entity (Obj)))
and then Nkind (Renamed_Object (Entity (Obj))) =
N_Explicit_Dereference);
end Denotes_Explicit_Dereference;
----------------------------------------
-- Is_Aliased_Unconstrained_Component --
----------------------------------------
function Is_Aliased_Unconstrained_Component return Boolean is
Comp : Entity_Id;
Pref : Node_Id;
begin
if Nkind (Lhs) /= N_Selected_Component then
return False;
else
Comp := Entity (Selector_Name (Lhs));
Pref := Prefix (Lhs);
end if;
if Ekind (Comp) /= E_Component
or else not Is_Aliased (Comp)
then
return False;
end if;
return not Comes_From_Source (Pref)
and then In_Instance
and then not Is_Constrained (Etype (Comp));
end Is_Aliased_Unconstrained_Component;
-- Start of processing for Apply_Discriminant_Check
begin
if Do_Access then
T_Typ := Designated_Type (Typ);
else
T_Typ := Typ;
end if;
-- Nothing to do if discriminant checks are suppressed or else no code
-- is to be generated
if not Full_Expander_Active
or else Discriminant_Checks_Suppressed (T_Typ)
then
return;
end if;
-- No discriminant checks necessary for an access when expression is
-- statically Null. This is not only an optimization, it is fundamental
-- because otherwise discriminant checks may be generated in init procs
-- for types containing an access to a not-yet-frozen record, causing a
-- deadly forward reference.
-- Also, if the expression is of an access type whose designated type is
-- incomplete, then the access value must be null and we suppress the
-- check.
if Known_Null (N) then
return;
elsif Is_Access_Type (S_Typ) then
S_Typ := Designated_Type (S_Typ);
if Ekind (S_Typ) = E_Incomplete_Type then
return;
end if;
end if;
-- If an assignment target is present, then we need to generate the
-- actual subtype if the target is a parameter or aliased object with
-- an unconstrained nominal subtype.
-- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
-- subtype to the parameter and dereference cases, since other aliased
-- objects are unconstrained (unless the nominal subtype is explicitly
-- constrained).
if Present (Lhs)
and then (Present (Param_Entity (Lhs))
or else (Ada_Version < Ada_2005
and then not Is_Constrained (T_Typ)
and then Is_Aliased_View (Lhs)
and then not Is_Aliased_Unconstrained_Component)
or else (Ada_Version >= Ada_2005
and then not Is_Constrained (T_Typ)
and then Denotes_Explicit_Dereference (Lhs)
and then Nkind (Original_Node (Lhs)) /=
N_Function_Call))
then
T_Typ := Get_Actual_Subtype (Lhs);
end if;
-- Nothing to do if the type is unconstrained (this is the case where
-- the actual subtype in the RM sense of N is unconstrained and no check
-- is required).
if not Is_Constrained (T_Typ) then
return;
-- Ada 2005: nothing to do if the type is one for which there is a
-- partial view that is constrained.
elsif Ada_Version >= Ada_2005
and then Effectively_Has_Constrained_Partial_View
(Typ => Base_Type (T_Typ),
Scop => Current_Scope)
then
return;
end if;
-- Nothing to do if the type is an Unchecked_Union
if Is_Unchecked_Union (Base_Type (T_Typ)) then
return;
end if;
-- Suppress checks if the subtypes are the same. the check must be
-- preserved in an assignment to a formal, because the constraint is
-- given by the actual.
if Nkind (Original_Node (N)) /= N_Allocator
and then (No (Lhs)
or else not Is_Entity_Name (Lhs)
or else No (Param_Entity (Lhs)))
then
if (Etype (N) = Typ
or else (Do_Access and then Designated_Type (Typ) = S_Typ))
and then not Is_Aliased_View (Lhs)
then
return;
end if;
-- We can also eliminate checks on allocators with a subtype mark that
-- coincides with the context type. The context type may be a subtype
-- without a constraint (common case, a generic actual).
elsif Nkind (Original_Node (N)) = N_Allocator
and then Is_Entity_Name (Expression (Original_Node (N)))
then
declare
Alloc_Typ : constant Entity_Id :=
Entity (Expression (Original_Node (N)));
begin
if Alloc_Typ = T_Typ
or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
and then Is_Entity_Name (
Subtype_Indication (Parent (T_Typ)))
and then Alloc_Typ = Base_Type (T_Typ))
then
return;
end if;
end;
end if;
-- See if we have a case where the types are both constrained, and all
-- the constraints are constants. In this case, we can do the check
-- successfully at compile time.
-- We skip this check for the case where the node is rewritten`as
-- an allocator, because it already carries the context subtype,
-- and extracting the discriminants from the aggregate is messy.
if Is_Constrained (S_Typ)
and then Nkind (Original_Node (N)) /= N_Allocator
then
declare
DconT : Elmt_Id;
Discr : Entity_Id;
DconS : Elmt_Id;
ItemS : Node_Id;
ItemT : Node_Id;
begin
-- S_Typ may not have discriminants in the case where it is a
-- private type completed by a default discriminated type. In that
-- case, we need to get the constraints from the underlying_type.
-- If the underlying type is unconstrained (i.e. has no default
-- discriminants) no check is needed.
if Has_Discriminants (S_Typ) then
Discr := First_Discriminant (S_Typ);
DconS := First_Elmt (Discriminant_Constraint (S_Typ));
else
Discr := First_Discriminant (Underlying_Type (S_Typ));
DconS :=
First_Elmt
(Discriminant_Constraint (Underlying_Type (S_Typ)));
if No (DconS) then
return;
end if;
-- A further optimization: if T_Typ is derived from S_Typ
-- without imposing a constraint, no check is needed.
if Nkind (Original_Node (Parent (T_Typ))) =
N_Full_Type_Declaration
then
declare
Type_Def : constant Node_Id :=
Type_Definition (Original_Node (Parent (T_Typ)));
begin
if Nkind (Type_Def) = N_Derived_Type_Definition
and then Is_Entity_Name (Subtype_Indication (Type_Def))
and then Entity (Subtype_Indication (Type_Def)) = S_Typ
then
return;
end if;
end;
end if;
end if;
-- Constraint may appear in full view of type
if Ekind (T_Typ) = E_Private_Subtype
and then Present (Full_View (T_Typ))
then
DconT :=
First_Elmt (Discriminant_Constraint (Full_View (T_Typ)));
else
DconT :=
First_Elmt (Discriminant_Constraint (T_Typ));
end if;
while Present (Discr) loop
ItemS := Node (DconS);
ItemT := Node (DconT);
-- For a discriminated component type constrained by the
-- current instance of an enclosing type, there is no
-- applicable discriminant check.
if Nkind (ItemT) = N_Attribute_Reference
and then Is_Access_Type (Etype (ItemT))
and then Is_Entity_Name (Prefix (ItemT))
and then Is_Type (Entity (Prefix (ItemT)))
then
return;
end if;
-- If the expressions for the discriminants are identical
-- and it is side-effect free (for now just an entity),
-- this may be a shared constraint, e.g. from a subtype
-- without a constraint introduced as a generic actual.
-- Examine other discriminants if any.
if ItemS = ItemT
and then Is_Entity_Name (ItemS)
then
null;
elsif not Is_OK_Static_Expression (ItemS)
or else not Is_OK_Static_Expression (ItemT)
then
exit;
elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
if Do_Access then -- needs run-time check.
exit;
else
Apply_Compile_Time_Constraint_Error
(N, "incorrect value for discriminant&??",
CE_Discriminant_Check_Failed, Ent => Discr);
return;
end if;
end if;
Next_Elmt (DconS);
Next_Elmt (DconT);
Next_Discriminant (Discr);
end loop;
if No (Discr) then
return;
end if;
end;
end if;
-- Here we need a discriminant check. First build the expression
-- for the comparisons of the discriminants:
-- (n.disc1 /= typ.disc1) or else
-- (n.disc2 /= typ.disc2) or else
-- ...
-- (n.discn /= typ.discn)
Cond := Build_Discriminant_Checks (N, T_Typ);
-- If Lhs is set and is a parameter, then the condition is guarded by:
-- lhs'constrained and then (condition built above)
if Present (Param_Entity (Lhs)) then
Cond :=
Make_And_Then (Loc,
Left_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
Attribute_Name => Name_Constrained),
Right_Opnd => Cond);
end if;
if Do_Access then
Cond := Guard_Access (Cond, Loc, N);
end if;
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition => Cond,
Reason => CE_Discriminant_Check_Failed));
end Apply_Discriminant_Check;
-------------------------
-- Apply_Divide_Checks --
-------------------------
procedure Apply_Divide_Checks (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
Left : constant Node_Id := Left_Opnd (N);
Right : constant Node_Id := Right_Opnd (N);
Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
-- Current overflow checking mode
LLB : Uint;
Llo : Uint;
Lhi : Uint;
LOK : Boolean;
Rlo : Uint;
Rhi : Uint;
ROK : Boolean;
pragma Warnings (Off, Lhi);
-- Don't actually use this value
begin
-- If we are operating in MINIMIZED or ELIMINATED mode, and we are
-- operating on signed integer types, then the only thing this routine
-- does is to call Apply_Arithmetic_Overflow_Minimized_Eliminated. That
-- procedure will (possibly later on during recursive downward calls),
-- ensure that any needed overflow/division checks are properly applied.
if Mode in Minimized_Or_Eliminated
and then Is_Signed_Integer_Type (Typ)
then
Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
return;
end if;
-- Proceed here in SUPPRESSED or CHECKED modes
if Full_Expander_Active
and then not Backend_Divide_Checks_On_Target
and then Check_Needed (Right, Division_Check)
then
Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
-- Deal with division check
if Do_Division_Check (N)
and then not Division_Checks_Suppressed (Typ)
then
Apply_Division_Check (N, Rlo, Rhi, ROK);
end if;
-- Deal with overflow check
if Do_Overflow_Check (N)
and then not Overflow_Checks_Suppressed (Etype (N))
then
-- Test for extremely annoying case of xxx'First divided by -1
-- for division of signed integer types (only overflow case).
if Nkind (N) = N_Op_Divide
and then Is_Signed_Integer_Type (Typ)
then
Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
and then
((not LOK) or else (Llo = LLB))
then
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_And_Then (Loc,
Left_Opnd =>
Make_Op_Eq (Loc,
Left_Opnd =>
Duplicate_Subexpr_Move_Checks (Left),
Right_Opnd => Make_Integer_Literal (Loc, LLB)),
Right_Opnd =>
Make_Op_Eq (Loc,
Left_Opnd => Duplicate_Subexpr (Right),
Right_Opnd => Make_Integer_Literal (Loc, -1))),
Reason => CE_Overflow_Check_Failed));
end if;
end if;
end if;
end if;
end Apply_Divide_Checks;
--------------------------
-- Apply_Division_Check --
--------------------------
procedure Apply_Division_Check
(N : Node_Id;
Rlo : Uint;
Rhi : Uint;
ROK : Boolean)
is
pragma Assert (Do_Division_Check (N));
Loc : constant Source_Ptr := Sloc (N);
Right : constant Node_Id := Right_Opnd (N);
begin
if Full_Expander_Active
and then not Backend_Divide_Checks_On_Target
and then Check_Needed (Right, Division_Check)
then
-- See if division by zero possible, and if so generate test. This
-- part of the test is not controlled by the -gnato switch, since
-- it is a Division_Check and not an Overflow_Check.
if Do_Division_Check (N) then
if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Op_Eq (Loc,
Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
Right_Opnd => Make_Integer_Literal (Loc, 0)),
Reason => CE_Divide_By_Zero));
end if;
end if;
end if;
end Apply_Division_Check;
----------------------------------
-- Apply_Float_Conversion_Check --
----------------------------------
-- Let F and I be the source and target types of the conversion. The RM
-- specifies that a floating-point value X is rounded to the nearest
-- integer, with halfway cases being rounded away from zero. The rounded
-- value of X is checked against I'Range.
-- The catch in the above paragraph is that there is no good way to know
-- whether the round-to-integer operation resulted in overflow. A remedy is
-- to perform a range check in the floating-point domain instead, however:
-- (1) The bounds may not be known at compile time
-- (2) The check must take into account rounding or truncation.
-- (3) The range of type I may not be exactly representable in F.
-- (4) For the rounding case, The end-points I'First - 0.5 and
-- I'Last + 0.5 may or may not be in range, depending on the
-- sign of I'First and I'Last.
-- (5) X may be a NaN, which will fail any comparison
-- The following steps correctly convert X with rounding:
-- (1) If either I'First or I'Last is not known at compile time, use
-- I'Base instead of I in the next three steps and perform a
-- regular range check against I'Range after conversion.
-- (2) If I'First - 0.5 is representable in F then let Lo be that
-- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
-- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
-- In other words, take one of the closest floating-point numbers
-- (which is an integer value) to I'First, and see if it is in
-- range or not.
-- (3) If I'Last + 0.5 is representable in F then let Hi be that value
-- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
-- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
-- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
-- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
-- For the truncating case, replace steps (2) and (3) as follows:
-- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
-- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
-- Lo_OK be True.
-- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
-- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
-- Hi_OK be True.
procedure Apply_Float_Conversion_Check
(Ck_Node : Node_Id;
Target_Typ : Entity_Id)
is
LB : constant Node_Id := Type_Low_Bound (Target_Typ);
HB : constant Node_Id := Type_High_Bound (Target_Typ);
Loc : constant Source_Ptr := Sloc (Ck_Node);
Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
Target_Base : constant Entity_Id :=
Implementation_Base_Type (Target_Typ);
Par : constant Node_Id := Parent (Ck_Node);
pragma Assert (Nkind (Par) = N_Type_Conversion);
-- Parent of check node, must be a type conversion
Truncate : constant Boolean := Float_Truncate (Par);
Max_Bound : constant Uint :=
UI_Expon
(Machine_Radix_Value (Expr_Type),
Machine_Mantissa_Value (Expr_Type) - 1) - 1;
-- Largest bound, so bound plus or minus half is a machine number of F
Ifirst, Ilast : Uint;
-- Bounds of integer type
Lo, Hi : Ureal;
-- Bounds to check in floating-point domain
Lo_OK, Hi_OK : Boolean;
-- True iff Lo resp. Hi belongs to I'Range
Lo_Chk, Hi_Chk : Node_Id;
-- Expressions that are False iff check fails
Reason : RT_Exception_Code;
begin
if not Compile_Time_Known_Value (LB)
or not Compile_Time_Known_Value (HB)
then
declare
-- First check that the value falls in the range of the base type,
-- to prevent overflow during conversion and then perform a
-- regular range check against the (dynamic) bounds.
pragma Assert (Target_Base /= Target_Typ);
Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par);
begin
Apply_Float_Conversion_Check (Ck_Node, Target_Base);
Set_Etype (Temp, Target_Base);
Insert_Action (Parent (Par),
Make_Object_Declaration (Loc,
Defining_Identifier => Temp,
Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
Expression => New_Copy_Tree (Par)),
Suppress => All_Checks);
Insert_Action (Par,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd => New_Occurrence_Of (Temp, Loc),
Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
Reason => CE_Range_Check_Failed));
Rewrite (Par, New_Occurrence_Of (Temp, Loc));
return;
end;
end if;
-- Get the (static) bounds of the target type
Ifirst := Expr_Value (LB);
Ilast := Expr_Value (HB);
-- A simple optimization: if the expression is a universal literal,
-- we can do the comparison with the bounds and the conversion to
-- an integer type statically. The range checks are unchanged.
if Nkind (Ck_Node) = N_Real_Literal
and then Etype (Ck_Node) = Universal_Real
and then Is_Integer_Type (Target_Typ)
and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
then
declare
Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
begin
if Int_Val <= Ilast and then Int_Val >= Ifirst then
-- Conversion is safe
Rewrite (Parent (Ck_Node),
Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
return;
end if;
end;
end if;
-- Check against lower bound
if Truncate and then Ifirst > 0 then
Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
Lo_OK := False;
elsif Truncate then
Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
Lo_OK := True;
elsif abs (Ifirst) < Max_Bound then
Lo := UR_From_Uint (Ifirst) - Ureal_Half;
Lo_OK := (Ifirst > 0);
else
Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
Lo_OK := (Lo >= UR_From_Uint (Ifirst));
end if;
if Lo_OK then
-- Lo_Chk := (X >= Lo)
Lo_Chk := Make_Op_Ge (Loc,
Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
Right_Opnd => Make_Real_Literal (Loc, Lo));
else
-- Lo_Chk := (X > Lo)
Lo_Chk := Make_Op_Gt (Loc,
Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
Right_Opnd => Make_Real_Literal (Loc, Lo));
end if;
-- Check against higher bound
if Truncate and then Ilast < 0 then
Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
Hi_OK := False;
elsif Truncate then
Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
Hi_OK := True;
elsif abs (Ilast) < Max_Bound then
Hi := UR_From_Uint (Ilast) + Ureal_Half;
Hi_OK := (Ilast < 0);
else
Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
Hi_OK := (Hi <= UR_From_Uint (Ilast));
end if;
if Hi_OK then
-- Hi_Chk := (X <= Hi)
Hi_Chk := Make_Op_Le (Loc,
Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
Right_Opnd => Make_Real_Literal (Loc, Hi));
else
-- Hi_Chk := (X < Hi)
Hi_Chk := Make_Op_Lt (Loc,
Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
Right_Opnd => Make_Real_Literal (Loc, Hi));
end if;
-- If the bounds of the target type are the same as those of the base
-- type, the check is an overflow check as a range check is not
-- performed in these cases.
if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
then
Reason := CE_Overflow_Check_Failed;
else
Reason := CE_Range_Check_Failed;
end if;
-- Raise CE if either conditions does not hold
Insert_Action (Ck_Node,
Make_Raise_Constraint_Error (Loc,
Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
Reason => Reason));
end Apply_Float_Conversion_Check;
------------------------
-- Apply_Length_Check --
------------------------
procedure Apply_Length_Check
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id := Empty)
is
begin
Apply_Selected_Length_Checks
(Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
end Apply_Length_Check;
-------------------------------------
-- Apply_Parameter_Aliasing_Checks --
-------------------------------------
procedure Apply_Parameter_Aliasing_Checks
(Call : Node_Id;
Subp : Entity_Id)
is
function May_Cause_Aliasing
(Formal_1 : Entity_Id;
Formal_2 : Entity_Id) return Boolean;
-- Determine whether two formal parameters can alias each other
-- depending on their modes.
function Original_Actual (N : Node_Id) return Node_Id;
-- The expander may replace an actual with a temporary for the sake of
-- side effect removal. The temporary may hide a potential aliasing as
-- it does not share the address of the actual. This routine attempts
-- to retrieve the original actual.
------------------------
-- May_Cause_Aliasing --
------------------------
function May_Cause_Aliasing
(Formal_1 : Entity_Id;
Formal_2 : Entity_Id) return Boolean
is
begin
-- The following combination cannot lead to aliasing
-- Formal 1 Formal 2
-- IN IN
if Ekind (Formal_1) = E_In_Parameter
and then
Ekind (Formal_2) = E_In_Parameter
then
return False;
-- The following combinations may lead to aliasing
-- Formal 1 Formal 2
-- IN OUT
-- IN IN OUT
-- OUT IN
-- OUT IN OUT
-- OUT OUT
else
return True;
end if;
end May_Cause_Aliasing;
---------------------
-- Original_Actual --
---------------------
function Original_Actual (N : Node_Id) return Node_Id is
begin
if Nkind (N) = N_Type_Conversion then
return Expression (N);
-- The expander created a temporary to capture the result of a type
-- conversion where the expression is the real actual.
elsif Nkind (N) = N_Identifier
and then Present (Original_Node (N))
and then Nkind (Original_Node (N)) = N_Type_Conversion
then
return Expression (Original_Node (N));
end if;
return N;
end Original_Actual;
-- Local variables
Loc : constant Source_Ptr := Sloc (Call);
Actual_1 : Node_Id;
Actual_2 : Node_Id;
Check : Node_Id;
Cond : Node_Id;
Formal_1 : Entity_Id;
Formal_2 : Entity_Id;
-- Start of processing for Apply_Parameter_Aliasing_Checks
begin
Cond := Empty;
Actual_1 := First_Actual (Call);
Formal_1 := First_Formal (Subp);
while Present (Actual_1) and then Present (Formal_1) loop
-- Ensure that the actual is an object that is not passed by value.
-- Elementary types are always passed by value, therefore actuals of
-- such types cannot lead to aliasing.
if Is_Object_Reference (Original_Actual (Actual_1))
and then not Is_Elementary_Type (Etype (Original_Actual (Actual_1)))
then
Actual_2 := Next_Actual (Actual_1);
Formal_2 := Next_Formal (Formal_1);
while Present (Actual_2) and then Present (Formal_2) loop
-- The other actual we are testing against must also denote
-- a non pass-by-value object. Generate the check only when
-- the mode of the two formals may lead to aliasing.
if Is_Object_Reference (Original_Actual (Actual_2))
and then not
Is_Elementary_Type (Etype (Original_Actual (Actual_2)))
and then May_Cause_Aliasing (Formal_1, Formal_2)
then
-- Generate:
-- Actual_1'Overlaps_Storage (Actual_2)
Check :=
Make_Attribute_Reference (Loc,
Prefix =>
New_Copy_Tree (Original_Actual (Actual_1)),
Attribute_Name => Name_Overlaps_Storage,
Expressions =>
New_List (New_Copy_Tree (Original_Actual (Actual_2))));
if No (Cond) then
Cond := Check;
else
Cond :=
Make_And_Then (Loc,
Left_Opnd => Cond,
Right_Opnd => Check);
end if;
end if;
Next_Actual (Actual_2);
Next_Formal (Formal_2);
end loop;
end if;
Next_Actual (Actual_1);
Next_Formal (Formal_1);
end loop;
-- Place the check right before the call
if Present (Cond) then
Insert_Action (Call,
Make_Raise_Program_Error (Loc,
Condition => Cond,
Reason => PE_Explicit_Raise));
end if;
end Apply_Parameter_Aliasing_Checks;
-------------------------------------
-- Apply_Parameter_Validity_Checks --
-------------------------------------
procedure Apply_Parameter_Validity_Checks (Subp : Entity_Id) is
Subp_Decl : Node_Id;
procedure Add_Validity_Check
(Context : Entity_Id;
PPC_Nam : Name_Id;
For_Result : Boolean := False);
-- Add a single 'Valid[_Scalar] check which verifies the initialization
-- of Context. PPC_Nam denotes the pre or post condition pragma name.
-- Set flag For_Result when to verify the result of a function.
procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id);
-- Create a pre or post condition pragma with name PPC_Nam which
-- tests expression Check.
------------------------
-- Add_Validity_Check --
------------------------
procedure Add_Validity_Check
(Context : Entity_Id;
PPC_Nam : Name_Id;
For_Result : Boolean := False)
is
Loc : constant Source_Ptr := Sloc (Subp);
Typ : constant Entity_Id := Etype (Context);
Check : Node_Id;
Nam : Name_Id;
begin
-- Pick the proper version of 'Valid depending on the type of the
-- context. If the context is not eligible for such a check, return.
if Is_Scalar_Type (Typ) then
Nam := Name_Valid;
elsif not No_Scalar_Parts (Typ) then
Nam := Name_Valid_Scalars;
else
return;
end if;
-- Step 1: Create the expression to verify the validity of the
-- context.
Check := New_Reference_To (Context, Loc);
-- When processing a function result, use 'Result. Generate
-- Context'Result
if For_Result then
Check :=
Make_Attribute_Reference (Loc,
Prefix => Check,
Attribute_Name => Name_Result);
end if;
-- Generate:
-- Context['Result]'Valid[_Scalars]
Check :=
Make_Attribute_Reference (Loc,
Prefix => Check,
Attribute_Name => Nam);
-- Step 2: Create a pre or post condition pragma
Build_PPC_Pragma (PPC_Nam, Check);
end Add_Validity_Check;
----------------------
-- Build_PPC_Pragma --
----------------------
procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id) is
Loc : constant Source_Ptr := Sloc (Subp);
Decls : List_Id;
Prag : Node_Id;
begin
Prag :=
Make_Pragma (Loc,
Pragma_Identifier => Make_Identifier (Loc, PPC_Nam),
Pragma_Argument_Associations => New_List (
Make_Pragma_Argument_Association (Loc,
Chars => Name_Check,
Expression => Check)));
-- Add a message unless exception messages are suppressed
if not Exception_Locations_Suppressed then
Append_To (Pragma_Argument_Associations (Prag),
Make_Pragma_Argument_Association (Loc,
Chars => Name_Message,
Expression =>
Make_String_Literal (Loc,
Strval => "failed " & Get_Name_String (PPC_Nam) &
" from " & Build_Location_String (Loc))));
end if;
-- Insert the pragma in the tree
if Nkind (Parent (Subp_Decl)) = N_Compilation_Unit then
Add_Global_Declaration (Prag);
Analyze (Prag);
-- PPC pragmas associated with subprogram bodies must be inserted in
-- the declarative part of the body.
elsif Nkind (Subp_Decl) = N_Subprogram_Body then
Decls := Declarations (Subp_Decl);
if No (Decls) then
Decls := New_List;
Set_Declarations (Subp_Decl, Decls);
end if;
Prepend_To (Decls, Prag);
-- Ensure the proper visibility of the subprogram body and its
-- parameters.
Push_Scope (Subp);
Analyze (Prag);
Pop_Scope;
-- For subprogram declarations insert the PPC pragma right after the
-- declarative node.
else
Insert_After_And_Analyze (Subp_Decl, Prag);
end if;
end Build_PPC_Pragma;
-- Local variables
Formal : Entity_Id;
Subp_Spec : Node_Id;
-- Start of processing for Apply_Parameter_Validity_Checks
begin
-- Extract the subprogram specification and declaration nodes
Subp_Spec := Parent (Subp);
if Nkind (Subp_Spec) = N_Defining_Program_Unit_Name then
Subp_Spec := Parent (Subp_Spec);
end if;
Subp_Decl := Parent (Subp_Spec);
if not Comes_From_Source (Subp)
-- Do not process formal subprograms because the corresponding actual
-- will receive the proper checks when the instance is analyzed.
or else Is_Formal_Subprogram (Subp)
-- Do not process imported subprograms since pre and post conditions
-- are never verified on routines coming from a different language.
or else Is_Imported (Subp)
or else Is_Intrinsic_Subprogram (Subp)
-- The PPC pragmas generated by this routine do not correspond to
-- source aspects, therefore they cannot be applied to abstract
-- subprograms.
or else Nkind (Subp_Decl) = N_Abstract_Subprogram_Declaration
-- Do not consider subprogram renaminds because the renamed entity
-- already has the proper PPC pragmas.
or else Nkind (Subp_Decl) = N_Subprogram_Renaming_Declaration
-- Do not process null procedures because there is no benefit of
-- adding the checks to a no action routine.
or else (Nkind (Subp_Spec) = N_Procedure_Specification
and then Null_Present (Subp_Spec))
then
return;
end if;
-- Inspect all the formals applying aliasing and scalar initialization
-- checks where applicable.
Formal := First_Formal (Subp);
while Present (Formal) loop
-- Generate the following scalar initialization checks for each
-- formal parameter:
-- mode IN - Pre => Formal'Valid[_Scalars]
-- mode IN OUT - Pre, Post => Formal'Valid[_Scalars]
-- mode OUT - Post => Formal'Valid[_Scalars]
if Check_Validity_Of_Parameters then
if Ekind_In (Formal, E_In_Parameter, E_In_Out_Parameter) then
Add_Validity_Check (Formal, Name_Precondition, False);
end if;
if Ekind_In (Formal, E_In_Out_Parameter, E_Out_Parameter) then
Add_Validity_Check (Formal, Name_Postcondition, False);
end if;
end if;
Next_Formal (Formal);
end loop;
-- Generate following scalar initialization check for function result:
-- Post => Subp'Result'Valid[_Scalars]
if Check_Validity_Of_Parameters and then Ekind (Subp) = E_Function then
Add_Validity_Check (Subp, Name_Postcondition, True);
end if;
end Apply_Parameter_Validity_Checks;
---------------------------
-- Apply_Predicate_Check --
---------------------------
procedure Apply_Predicate_Check (N : Node_Id; Typ : Entity_Id) is
S : Entity_Id;
begin
if Present (Predicate_Function (Typ)) then
-- A predicate check does not apply within internally generated
-- subprograms, such as TSS functions.
S := Current_Scope;
while Present (S) and then not Is_Subprogram (S) loop
S := Scope (S);
end loop;
if Present (S) and then Get_TSS_Name (S) /= TSS_Null then
return;
-- If the check appears within the predicate function itself, it
-- means that the user specified a check whose formal is the
-- predicated subtype itself, rather than some covering type. This
-- is likely to be a common error, and thus deserves a warning.
elsif S = Predicate_Function (Typ) then
Error_Msg_N
("predicate check includes a function call that "
& "requires a predicate check??", Parent (N));
Error_Msg_N
("\this will result in infinite recursion??", Parent (N));
Insert_Action (N,
Make_Raise_Storage_Error (Sloc (N),
Reason => SE_Infinite_Recursion));
-- Here for normal case of predicate active.
else
-- If the predicate is a static predicate and the operand is
-- static, the predicate must be evaluated statically. If the
-- evaluation fails this is a static constraint error. This check
-- is disabled in -gnatc mode, because the compiler is incapable
-- of evaluating static expressions in that case.
if Is_OK_Static_Expression (N) then
if Present (Static_Predicate (Typ)) then
if Operating_Mode < Generate_Code
or else Eval_Static_Predicate_Check (N, Typ)
then
return;
else
Error_Msg_NE
("static expression fails static predicate check on&",
N, Typ);
end if;
end if;
end if;
Insert_Action (N,
Make_Predicate_Check (Typ, Duplicate_Subexpr (N)));
end if;
end if;
end Apply_Predicate_Check;
-----------------------
-- Apply_Range_Check --
-----------------------
procedure Apply_Range_Check
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id := Empty)
is
begin
Apply_Selected_Range_Checks
(Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
end Apply_Range_Check;
------------------------------
-- Apply_Scalar_Range_Check --
------------------------------
-- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
-- off if it is already set on.
procedure Apply_Scalar_Range_Check
(Expr : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id := Empty;
Fixed_Int : Boolean := False)
is
Parnt : constant Node_Id := Parent (Expr);
S_Typ : Entity_Id;
Arr : Node_Id := Empty; -- initialize to prevent warning
Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
OK : Boolean;
Is_Subscr_Ref : Boolean;
-- Set true if Expr is a subscript
Is_Unconstrained_Subscr_Ref : Boolean;
-- Set true if Expr is a subscript of an unconstrained array. In this
-- case we do not attempt to do an analysis of the value against the
-- range of the subscript, since we don't know the actual subtype.
Int_Real : Boolean;
-- Set to True if Expr should be regarded as a real value even though
-- the type of Expr might be discrete.
procedure Bad_Value;
-- Procedure called if value is determined to be out of range
---------------
-- Bad_Value --
---------------
procedure Bad_Value is
begin
Apply_Compile_Time_Constraint_Error
(Expr, "value not in range of}??", CE_Range_Check_Failed,
Ent => Target_Typ,
Typ => Target_Typ);
end Bad_Value;
-- Start of processing for Apply_Scalar_Range_Check
begin
-- Return if check obviously not needed
if
-- Not needed inside generic
Inside_A_Generic
-- Not needed if previous error
or else Target_Typ = Any_Type
or else Nkind (Expr) = N_Error
-- Not needed for non-scalar type
or else not Is_Scalar_Type (Target_Typ)
-- Not needed if we know node raises CE already
or else Raises_Constraint_Error (Expr)
then
return;
end if;
-- Now, see if checks are suppressed
Is_Subscr_Ref :=
Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
if Is_Subscr_Ref then
Arr := Prefix (Parnt);
Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
if Is_Access_Type (Arr_Typ) then
Arr_Typ := Designated_Type (Arr_Typ);
end if;
end if;
if not Do_Range_Check (Expr) then
-- Subscript reference. Check for Index_Checks suppressed
if Is_Subscr_Ref then
-- Check array type and its base type
if Index_Checks_Suppressed (Arr_Typ)
or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
then
return;
-- Check array itself if it is an entity name
elsif Is_Entity_Name (Arr)
and then Index_Checks_Suppressed (Entity (Arr))
then
return;
-- Check expression itself if it is an entity name
elsif Is_Entity_Name (Expr)
and then Index_Checks_Suppressed (Entity (Expr))
then
return;
end if;
-- All other cases, check for Range_Checks suppressed
else
-- Check target type and its base type
if Range_Checks_Suppressed (Target_Typ)
or else Range_Checks_Suppressed (Base_Type (Target_Typ))
then
return;
-- Check expression itself if it is an entity name
elsif Is_Entity_Name (Expr)
and then Range_Checks_Suppressed (Entity (Expr))
then
return;
-- If Expr is part of an assignment statement, then check left
-- side of assignment if it is an entity name.
elsif Nkind (Parnt) = N_Assignment_Statement
and then Is_Entity_Name (Name (Parnt))
and then Range_Checks_Suppressed (Entity (Name (Parnt)))
then
return;
end if;
end if;
end if;
-- Do not set range checks if they are killed
if Nkind (Expr) = N_Unchecked_Type_Conversion
and then Kill_Range_Check (Expr)
then
return;
end if;
-- Do not set range checks for any values from System.Scalar_Values
-- since the whole idea of such values is to avoid checking them!
if Is_Entity_Name (Expr)
and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
then
return;
end if;
-- Now see if we need a check
if No (Source_Typ) then
S_Typ := Etype (Expr);
else
S_Typ := Source_Typ;
end if;
if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
return;
end if;
Is_Unconstrained_Subscr_Ref :=
Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
-- Special checks for floating-point type
if Is_Floating_Point_Type (S_Typ) then
-- Always do a range check if the source type includes infinities and
-- the target type does not include infinities. We do not do this if
-- range checks are killed.
if Has_Infinities (S_Typ)
and then not Has_Infinities (Target_Typ)
then
Enable_Range_Check (Expr);
-- Always do a range check for operators if option set
elsif Check_Float_Overflow and then Nkind (Expr) in N_Op then
Enable_Range_Check (Expr);
end if;
end if;
-- Return if we know expression is definitely in the range of the target
-- type as determined by Determine_Range. Right now we only do this for
-- discrete types, and not fixed-point or floating-point types.
-- The additional less-precise tests below catch these cases
-- Note: skip this if we are given a source_typ, since the point of
-- supplying a Source_Typ is to stop us looking at the expression.
-- We could sharpen this test to be out parameters only ???
if Is_Discrete_Type (Target_Typ)
and then Is_Discrete_Type (Etype (Expr))
and then not Is_Unconstrained_Subscr_Ref
and then No (Source_Typ)
then
declare
Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
Thi : constant Node_Id := Type_High_Bound (Target_Typ);
Lo : Uint;
Hi : Uint;
begin
if Compile_Time_Known_Value (Tlo)
and then Compile_Time_Known_Value (Thi)
then
declare
Lov : constant Uint := Expr_Value (Tlo);
Hiv : constant Uint := Expr_Value (Thi);
begin
-- If range is null, we for sure have a constraint error
-- (we don't even need to look at the value involved,
-- since all possible values will raise CE).
if Lov > Hiv then
Bad_Value;
return;
end if;
-- Otherwise determine range of value
Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
if OK then
-- If definitely in range, all OK
if Lo >= Lov and then Hi <= Hiv then
return;
-- If definitely not in range, warn
elsif Lov > Hi or else Hiv < Lo then
Bad_Value;
return;
-- Otherwise we don't know
else
null;
end if;
end if;
end;
end if;
end;
end if;
Int_Real :=
Is_Floating_Point_Type (S_Typ)
or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
-- Check if we can determine at compile time whether Expr is in the
-- range of the target type. Note that if S_Typ is within the bounds
-- of Target_Typ then this must be the case. This check is meaningful
-- only if this is not a conversion between integer and real types.
if not Is_Unconstrained_Subscr_Ref
and then Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
and then
(In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
or else
Is_In_Range (Expr, Target_Typ,
Assume_Valid => True,
Fixed_Int => Fixed_Int,
Int_Real => Int_Real))
then
return;
elsif Is_Out_Of_Range (Expr, Target_Typ,
Assume_Valid => True,
Fixed_Int => Fixed_Int,
Int_Real => Int_Real)
then
Bad_Value;
return;
-- Floating-point case
-- In the floating-point case, we only do range checks if the type is
-- constrained. We definitely do NOT want range checks for unconstrained
-- types, since we want to have infinities
elsif Is_Floating_Point_Type (S_Typ) then
-- Normally, we only do range checks if the type is constrained. We do
-- NOT want range checks for unconstrained types, since we want to have
-- infinities. Override this decision in Check_Float_Overflow mode.
if Is_Constrained (S_Typ) or else Check_Float_Overflow then
Enable_Range_Check (Expr);
end if;
-- For all other cases we enable a range check unconditionally
else
Enable_Range_Check (Expr);
return;
end if;
end Apply_Scalar_Range_Check;
----------------------------------
-- Apply_Selected_Length_Checks --
----------------------------------
procedure Apply_Selected_Length_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Do_Static : Boolean)
is
Cond : Node_Id;
R_Result : Check_Result;
R_Cno : Node_Id;
Loc : constant Source_Ptr := Sloc (Ck_Node);
Checks_On : constant Boolean :=
(not Index_Checks_Suppressed (Target_Typ))
or else (not Length_Checks_Suppressed (Target_Typ));
begin
if not Full_Expander_Active then
return;
end if;
R_Result :=
Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
for J in 1 .. 2 loop
R_Cno := R_Result (J);
exit when No (R_Cno);
-- A length check may mention an Itype which is attached to a
-- subsequent node. At the top level in a package this can cause
-- an order-of-elaboration problem, so we make sure that the itype
-- is referenced now.
if Ekind (Current_Scope) = E_Package
and then Is_Compilation_Unit (Current_Scope)
then
Ensure_Defined (Target_Typ, Ck_Node);
if Present (Source_Typ) then
Ensure_Defined (Source_Typ, Ck_Node);
elsif Is_Itype (Etype (Ck_Node)) then
Ensure_Defined (Etype (Ck_Node), Ck_Node);
end if;
end if;
-- If the item is a conditional raise of constraint error, then have
-- a look at what check is being performed and ???
if Nkind (R_Cno) = N_Raise_Constraint_Error
and then Present (Condition (R_Cno))
then
Cond := Condition (R_Cno);
-- Case where node does not now have a dynamic check
if not Has_Dynamic_Length_Check (Ck_Node) then
-- If checks are on, just insert the check
if Checks_On then
Insert_Action (Ck_Node, R_Cno);
if not Do_Static then
Set_Has_Dynamic_Length_Check (Ck_Node);
end if;
-- If checks are off, then analyze the length check after
-- temporarily attaching it to the tree in case the relevant
-- condition can be evaluated at compile time. We still want a
-- compile time warning in this case.
else
Set_Parent (R_Cno, Ck_Node);
Analyze (R_Cno);
end if;
end if;
-- Output a warning if the condition is known to be True
if Is_Entity_Name (Cond)
and then Entity (Cond) = Standard_True
then
Apply_Compile_Time_Constraint_Error
(Ck_Node, "wrong length for array of}??",
CE_Length_Check_Failed,
Ent => Target_Typ,
Typ => Target_Typ);
-- If we were only doing a static check, or if checks are not
-- on, then we want to delete the check, since it is not needed.
-- We do this by replacing the if statement by a null statement
elsif Do_Static or else not Checks_On then
Remove_Warning_Messages (R_Cno);
Rewrite (R_Cno, Make_Null_Statement (Loc));
end if;
else
Install_Static_Check (R_Cno, Loc);
end if;
end loop;
end Apply_Selected_Length_Checks;
---------------------------------
-- Apply_Selected_Range_Checks --
---------------------------------
procedure Apply_Selected_Range_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Do_Static : Boolean)
is
Cond : Node_Id;
R_Result : Check_Result;
R_Cno : Node_Id;
Loc : constant Source_Ptr := Sloc (Ck_Node);
Checks_On : constant Boolean :=
(not Index_Checks_Suppressed (Target_Typ))
or else (not Range_Checks_Suppressed (Target_Typ));
begin
if not Full_Expander_Active or else not Checks_On then
return;
end if;
R_Result :=
Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
for J in 1 .. 2 loop
R_Cno := R_Result (J);
exit when No (R_Cno);
-- If the item is a conditional raise of constraint error, then have
-- a look at what check is being performed and ???
if Nkind (R_Cno) = N_Raise_Constraint_Error
and then Present (Condition (R_Cno))
then
Cond := Condition (R_Cno);
if not Has_Dynamic_Range_Check (Ck_Node) then
Insert_Action (Ck_Node, R_Cno);
if not Do_Static then
Set_Has_Dynamic_Range_Check (Ck_Node);
end if;
end if;
-- Output a warning if the condition is known to be True
if Is_Entity_Name (Cond)
and then Entity (Cond) = Standard_True
then
-- Since an N_Range is technically not an expression, we have
-- to set one of the bounds to C_E and then just flag the
-- N_Range. The warning message will point to the lower bound
-- and complain about a range, which seems OK.
if Nkind (Ck_Node) = N_Range then
Apply_Compile_Time_Constraint_Error
(Low_Bound (Ck_Node), "static range out of bounds of}??",
CE_Range_Check_Failed,
Ent => Target_Typ,
Typ => Target_Typ);
Set_Raises_Constraint_Error (Ck_Node);
else
Apply_Compile_Time_Constraint_Error
(Ck_Node, "static value out of range of}?",
CE_Range_Check_Failed,
Ent => Target_Typ,
Typ => Target_Typ);
end if;
-- If we were only doing a static check, or if checks are not
-- on, then we want to delete the check, since it is not needed.
-- We do this by replacing the if statement by a null statement
elsif Do_Static or else not Checks_On then
Remove_Warning_Messages (R_Cno);
Rewrite (R_Cno, Make_Null_Statement (Loc));
end if;
else
Install_Static_Check (R_Cno, Loc);
end if;
end loop;
end Apply_Selected_Range_Checks;
-------------------------------
-- Apply_Static_Length_Check --
-------------------------------
procedure Apply_Static_Length_Check
(Expr : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id := Empty)
is
begin
Apply_Selected_Length_Checks
(Expr, Target_Typ, Source_Typ, Do_Static => True);
end Apply_Static_Length_Check;
-------------------------------------
-- Apply_Subscript_Validity_Checks --
-------------------------------------
procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
Sub : Node_Id;
begin
pragma Assert (Nkind (Expr) = N_Indexed_Component);
-- Loop through subscripts
Sub := First (Expressions (Expr));
while Present (Sub) loop
-- Check one subscript. Note that we do not worry about enumeration
-- type with holes, since we will convert the value to a Pos value
-- for the subscript, and that convert will do the necessary validity
-- check.
Ensure_Valid (Sub, Holes_OK => True);
-- Move to next subscript
Sub := Next (Sub);
end loop;
end Apply_Subscript_Validity_Checks;
----------------------------------
-- Apply_Type_Conversion_Checks --
----------------------------------
procedure Apply_Type_Conversion_Checks (N : Node_Id) is
Target_Type : constant Entity_Id := Etype (N);
Target_Base : constant Entity_Id := Base_Type (Target_Type);
Expr : constant Node_Id := Expression (N);
Expr_Type : constant Entity_Id := Underlying_Type (Etype (Expr));
-- Note: if Etype (Expr) is a private type without discriminants, its
-- full view might have discriminants with defaults, so we need the
-- full view here to retrieve the constraints.
begin
if Inside_A_Generic then
return;
-- Skip these checks if serious errors detected, there are some nasty
-- situations of incomplete trees that blow things up.
elsif Serious_Errors_Detected > 0 then
return;
-- Scalar type conversions of the form Target_Type (Expr) require a
-- range check if we cannot be sure that Expr is in the base type of
-- Target_Typ and also that Expr is in the range of Target_Typ. These
-- are not quite the same condition from an implementation point of
-- view, but clearly the second includes the first.
elsif Is_Scalar_Type (Target_Type) then
declare
Conv_OK : constant Boolean := Conversion_OK (N);
-- If the Conversion_OK flag on the type conversion is set and no
-- floating point type is involved in the type conversion then
-- fixed point values must be read as integral values.
Float_To_Int : constant Boolean :=
Is_Floating_Point_Type (Expr_Type)
and then Is_Integer_Type (Target_Type);
begin
if not Overflow_Checks_Suppressed (Target_Base)
and then not Overflow_Checks_Suppressed (Target_Type)
and then not
In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
and then not Float_To_Int
then
Activate_Overflow_Check (N);
end if;
if not Range_Checks_Suppressed (Target_Type)
and then not Range_Checks_Suppressed (Expr_Type)
then
if Float_To_Int then
Apply_Float_Conversion_Check (Expr, Target_Type);
else
Apply_Scalar_Range_Check
(Expr, Target_Type, Fixed_Int => Conv_OK);
-- If the target type has predicates, we need to indicate
-- the need for a check, even if Determine_Range finds
-- that the value is within bounds. This may be the case
-- e.g for a division with a constant denominator.
if Has_Predicates (Target_Type) then
Enable_Range_Check (Expr);
end if;
end if;
end if;
end;
elsif Comes_From_Source (N)
and then not Discriminant_Checks_Suppressed (Target_Type)
and then Is_Record_Type (Target_Type)
and then Is_Derived_Type (Target_Type)
and then not Is_Tagged_Type (Target_Type)
and then not Is_Constrained (Target_Type)
and then Present (Stored_Constraint (Target_Type))
then
-- An unconstrained derived type may have inherited discriminant.
-- Build an actual discriminant constraint list using the stored
-- constraint, to verify that the expression of the parent type
-- satisfies the constraints imposed by the (unconstrained!)
-- derived type. This applies to value conversions, not to view
-- conversions of tagged types.
declare
Loc : constant Source_Ptr := Sloc (N);
Cond : Node_Id;
Constraint : Elmt_Id;
Discr_Value : Node_Id;
Discr : Entity_Id;
New_Constraints : constant Elist_Id := New_Elmt_List;
Old_Constraints : constant Elist_Id :=
Discriminant_Constraint (Expr_Type);
begin
Constraint := First_Elmt (Stored_Constraint (Target_Type));
while Present (Constraint) loop
Discr_Value := Node (Constraint);
if Is_Entity_Name (Discr_Value)
and then Ekind (Entity (Discr_Value)) = E_Discriminant
then
Discr := Corresponding_Discriminant (Entity (Discr_Value));
if Present (Discr)
and then Scope (Discr) = Base_Type (Expr_Type)
then
-- Parent is constrained by new discriminant. Obtain
-- Value of original discriminant in expression. If the
-- new discriminant has been used to constrain more than
-- one of the stored discriminants, this will provide the
-- required consistency check.
Append_Elmt
(Make_Selected_Component (Loc,
Prefix =>
Duplicate_Subexpr_No_Checks
(Expr, Name_Req => True),
Selector_Name =>
Make_Identifier (Loc, Chars (Discr))),
New_Constraints);
else
-- Discriminant of more remote ancestor ???
return;
end if;
-- Derived type definition has an explicit value for this
-- stored discriminant.
else
Append_Elmt
(Duplicate_Subexpr_No_Checks (Discr_Value),
New_Constraints);
end if;
Next_Elmt (Constraint);
end loop;
-- Use the unconstrained expression type to retrieve the
-- discriminants of the parent, and apply momentarily the
-- discriminant constraint synthesized above.
Set_Discriminant_Constraint (Expr_Type, New_Constraints);
Cond := Build_Discriminant_Checks (Expr, Expr_Type);
Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition => Cond,
Reason => CE_Discriminant_Check_Failed));
end;
-- For arrays, conversions are applied during expansion, to take into
-- accounts changes of representation. The checks become range checks on
-- the base type or length checks on the subtype, depending on whether
-- the target type is unconstrained or constrained.
else
null;
end if;
end Apply_Type_Conversion_Checks;
----------------------------------------------
-- Apply_Universal_Integer_Attribute_Checks --
----------------------------------------------
procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
begin
if Inside_A_Generic then
return;
-- Nothing to do if checks are suppressed
elsif Range_Checks_Suppressed (Typ)
and then Overflow_Checks_Suppressed (Typ)
then
return;
-- Nothing to do if the attribute does not come from source. The
-- internal attributes we generate of this type do not need checks,
-- and furthermore the attempt to check them causes some circular
-- elaboration orders when dealing with packed types.
elsif not Comes_From_Source (N) then
return;
-- If the prefix is a selected component that depends on a discriminant
-- the check may improperly expose a discriminant instead of using
-- the bounds of the object itself. Set the type of the attribute to
-- the base type of the context, so that a check will be imposed when
-- needed (e.g. if the node appears as an index).
elsif Nkind (Prefix (N)) = N_Selected_Component
and then Ekind (Typ) = E_Signed_Integer_Subtype
and then Depends_On_Discriminant (Scalar_Range (Typ))
then
Set_Etype (N, Base_Type (Typ));
-- Otherwise, replace the attribute node with a type conversion node
-- whose expression is the attribute, retyped to universal integer, and
-- whose subtype mark is the target type. The call to analyze this
-- conversion will set range and overflow checks as required for proper
-- detection of an out of range value.
else
Set_Etype (N, Universal_Integer);
Set_Analyzed (N, True);
Rewrite (N,
Make_Type_Conversion (Loc,
Subtype_Mark => New_Occurrence_Of (Typ, Loc),
Expression => Relocate_Node (N)));
Analyze_And_Resolve (N, Typ);
return;
end if;
end Apply_Universal_Integer_Attribute_Checks;
-------------------------------------
-- Atomic_Synchronization_Disabled --
-------------------------------------
-- Note: internally Disable/Enable_Atomic_Synchronization is implemented
-- using a bogus check called Atomic_Synchronization. This is to make it
-- more convenient to get exactly the same semantics as [Un]Suppress.
function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is
begin
-- If debug flag d.e is set, always return False, i.e. all atomic sync
-- looks enabled, since it is never disabled.
if Debug_Flag_Dot_E then
return False;
-- If debug flag d.d is set then always return True, i.e. all atomic
-- sync looks disabled, since it always tests True.
elsif Debug_Flag_Dot_D then
return True;
-- If entity present, then check result for that entity
elsif Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Atomic_Synchronization);
-- Otherwise result depends on current scope setting
else
return Scope_Suppress.Suppress (Atomic_Synchronization);
end if;
end Atomic_Synchronization_Disabled;
-------------------------------
-- Build_Discriminant_Checks --
-------------------------------
function Build_Discriminant_Checks
(N : Node_Id;
T_Typ : Entity_Id) return Node_Id
is
Loc : constant Source_Ptr := Sloc (N);
Cond : Node_Id;
Disc : Elmt_Id;
Disc_Ent : Entity_Id;
Dref : Node_Id;
Dval : Node_Id;
function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
----------------------------------
-- Aggregate_Discriminant_Value --
----------------------------------
function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
Assoc : Node_Id;
begin
-- The aggregate has been normalized with named associations. We use
-- the Chars field to locate the discriminant to take into account
-- discriminants in derived types, which carry the same name as those
-- in the parent.
Assoc := First (Component_Associations (N));
while Present (Assoc) loop
if Chars (First (Choices (Assoc))) = Chars (Disc) then
return Expression (Assoc);
else
Next (Assoc);
end if;
end loop;
-- Discriminant must have been found in the loop above
raise Program_Error;
end Aggregate_Discriminant_Val;
-- Start of processing for Build_Discriminant_Checks
begin
-- Loop through discriminants evolving the condition
Cond := Empty;
Disc := First_Elmt (Discriminant_Constraint (T_Typ));
-- For a fully private type, use the discriminants of the parent type
if Is_Private_Type (T_Typ)
and then No (Full_View (T_Typ))
then
Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
else
Disc_Ent := First_Discriminant (T_Typ);
end if;
while Present (Disc) loop
Dval := Node (Disc);
if Nkind (Dval) = N_Identifier
and then Ekind (Entity (Dval)) = E_Discriminant
then
Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
else
Dval := Duplicate_Subexpr_No_Checks (Dval);
end if;
-- If we have an Unchecked_Union node, we can infer the discriminants
-- of the node.
if Is_Unchecked_Union (Base_Type (T_Typ)) then
Dref := New_Copy (
Get_Discriminant_Value (
First_Discriminant (T_Typ),
T_Typ,
Stored_Constraint (T_Typ)));
elsif Nkind (N) = N_Aggregate then
Dref :=
Duplicate_Subexpr_No_Checks
(Aggregate_Discriminant_Val (Disc_Ent));
else
Dref :=
Make_Selected_Component (Loc,
Prefix =>
Duplicate_Subexpr_No_Checks (N, Name_Req => True),
Selector_Name =>
Make_Identifier (Loc, Chars (Disc_Ent)));
Set_Is_In_Discriminant_Check (Dref);
end if;
Evolve_Or_Else (Cond,
Make_Op_Ne (Loc,
Left_Opnd => Dref,
Right_Opnd => Dval));
Next_Elmt (Disc);
Next_Discriminant (Disc_Ent);
end loop;
return Cond;
end Build_Discriminant_Checks;
------------------
-- Check_Needed --
------------------
function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
N : Node_Id;
P : Node_Id;
K : Node_Kind;
L : Node_Id;
R : Node_Id;
begin
-- Always check if not simple entity
if Nkind (Nod) not in N_Has_Entity
or else not Comes_From_Source (Nod)
then
return True;
end if;
-- Look up tree for short circuit
N := Nod;
loop
P := Parent (N);
K := Nkind (P);
-- Done if out of subexpression (note that we allow generated stuff
-- such as itype declarations in this context, to keep the loop going
-- since we may well have generated such stuff in complex situations.
-- Also done if no parent (probably an error condition, but no point
-- in behaving nasty if we find it!)
if No (P)
or else (K not in N_Subexpr and then Comes_From_Source (P))
then
return True;
-- Or/Or Else case, where test is part of the right operand, or is
-- part of one of the actions associated with the right operand, and
-- the left operand is an equality test.
elsif K = N_Op_Or then
exit when N = Right_Opnd (P)
and then Nkind (Left_Opnd (P)) = N_Op_Eq;
elsif K = N_Or_Else then
exit when (N = Right_Opnd (P)
or else
(Is_List_Member (N)
and then List_Containing (N) = Actions (P)))
and then Nkind (Left_Opnd (P)) = N_Op_Eq;
-- Similar test for the And/And then case, where the left operand
-- is an inequality test.
elsif K = N_Op_And then
exit when N = Right_Opnd (P)
and then Nkind (Left_Opnd (P)) = N_Op_Ne;
elsif K = N_And_Then then
exit when (N = Right_Opnd (P)
or else
(Is_List_Member (N)
and then List_Containing (N) = Actions (P)))
and then Nkind (Left_Opnd (P)) = N_Op_Ne;
end if;
N := P;
end loop;
-- If we fall through the loop, then we have a conditional with an
-- appropriate test as its left operand. So test further.
L := Left_Opnd (P);
R := Right_Opnd (L);
L := Left_Opnd (L);
-- Left operand of test must match original variable
if Nkind (L) not in N_Has_Entity
or else Entity (L) /= Entity (Nod)
then
return True;
end if;
-- Right operand of test must be key value (zero or null)
case Check is
when Access_Check =>
if not Known_Null (R) then
return True;
end if;
when Division_Check =>
if not Compile_Time_Known_Value (R)
or else Expr_Value (R) /= Uint_0
then
return True;
end if;
when others =>
raise Program_Error;
end case;
-- Here we have the optimizable case, warn if not short-circuited
if K = N_Op_And or else K = N_Op_Or then
case Check is
when Access_Check =>
Error_Msg_N
("Constraint_Error may be raised (access check)??",
Parent (Nod));
when Division_Check =>
Error_Msg_N
("Constraint_Error may be raised (zero divide)??",
Parent (Nod));
when others =>
raise Program_Error;
end case;
if K = N_Op_And then
Error_Msg_N -- CODEFIX
("use `AND THEN` instead of AND??", P);
else
Error_Msg_N -- CODEFIX
("use `OR ELSE` instead of OR??", P);
end if;
-- If not short-circuited, we need the check
return True;
-- If short-circuited, we can omit the check
else
return False;
end if;
end Check_Needed;
-----------------------------------
-- Check_Valid_Lvalue_Subscripts --
-----------------------------------
procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
begin
-- Skip this if range checks are suppressed
if Range_Checks_Suppressed (Etype (Expr)) then
return;
-- Only do this check for expressions that come from source. We assume
-- that expander generated assignments explicitly include any necessary
-- checks. Note that this is not just an optimization, it avoids
-- infinite recursions!
elsif not Comes_From_Source (Expr) then
return;
-- For a selected component, check the prefix
elsif Nkind (Expr) = N_Selected_Component then
Check_Valid_Lvalue_Subscripts (Prefix (Expr));
return;
-- Case of indexed component
elsif Nkind (Expr) = N_Indexed_Component then
Apply_Subscript_Validity_Checks (Expr);
-- Prefix may itself be or contain an indexed component, and these
-- subscripts need checking as well.
Check_Valid_Lvalue_Subscripts (Prefix (Expr));
end if;
end Check_Valid_Lvalue_Subscripts;
----------------------------------
-- Null_Exclusion_Static_Checks --
----------------------------------
procedure Null_Exclusion_Static_Checks (N : Node_Id) is
Error_Node : Node_Id;
Expr : Node_Id;
Has_Null : constant Boolean := Has_Null_Exclusion (N);
K : constant Node_Kind := Nkind (N);
Typ : Entity_Id;
begin
pragma Assert
(K = N_Component_Declaration
or else K = N_Discriminant_Specification
or else K = N_Function_Specification
or else K = N_Object_Declaration
or else K = N_Parameter_Specification);
if K = N_Function_Specification then
Typ := Etype (Defining_Entity (N));
else
Typ := Etype (Defining_Identifier (N));
end if;
case K is
when N_Component_Declaration =>
if Present (Access_Definition (Component_Definition (N))) then
Error_Node := Component_Definition (N);
else
Error_Node := Subtype_Indication (Component_Definition (N));
end if;
when N_Discriminant_Specification =>
Error_Node := Discriminant_Type (N);
when N_Function_Specification =>
Error_Node := Result_Definition (N);
when N_Object_Declaration =>
Error_Node := Object_Definition (N);
when N_Parameter_Specification =>
Error_Node := Parameter_Type (N);
when others =>
raise Program_Error;
end case;
if Has_Null then
-- Enforce legality rule 3.10 (13): A null exclusion can only be
-- applied to an access [sub]type.
if not Is_Access_Type (Typ) then
Error_Msg_N
("`NOT NULL` allowed only for an access type", Error_Node);
-- Enforce legality rule RM 3.10(14/1): A null exclusion can only
-- be applied to a [sub]type that does not exclude null already.
elsif Can_Never_Be_Null (Typ)
and then Comes_From_Source (Typ)
then
Error_Msg_NE
("`NOT NULL` not allowed (& already excludes null)",
Error_Node, Typ);
end if;
end if;
-- Check that null-excluding objects are always initialized, except for
-- deferred constants, for which the expression will appear in the full
-- declaration.
if K = N_Object_Declaration
and then No (Expression (N))
and then not Constant_Present (N)
and then not No_Initialization (N)
then
-- Add an expression that assigns null. This node is needed by
-- Apply_Compile_Time_Constraint_Error, which will replace this with
-- a Constraint_Error node.
Set_Expression (N, Make_Null (Sloc (N)));
Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
Apply_Compile_Time_Constraint_Error
(N => Expression (N),
Msg =>
"(Ada 2005) null-excluding objects must be initialized??",
Reason => CE_Null_Not_Allowed);
end if;
-- Check that a null-excluding component, formal or object is not being
-- assigned a null value. Otherwise generate a warning message and
-- replace Expression (N) by an N_Constraint_Error node.
if K /= N_Function_Specification then
Expr := Expression (N);
if Present (Expr) and then Known_Null (Expr) then
case K is
when N_Component_Declaration |
N_Discriminant_Specification =>
Apply_Compile_Time_Constraint_Error
(N => Expr,
Msg => "(Ada 2005) null not allowed " &
"in null-excluding components??",
Reason => CE_Null_Not_Allowed);
when N_Object_Declaration =>
Apply_Compile_Time_Constraint_Error
(N => Expr,
Msg => "(Ada 2005) null not allowed " &
"in null-excluding objects?",
Reason => CE_Null_Not_Allowed);
when N_Parameter_Specification =>
Apply_Compile_Time_Constraint_Error
(N => Expr,
Msg => "(Ada 2005) null not allowed " &
"in null-excluding formals??",
Reason => CE_Null_Not_Allowed);
when others =>
null;
end case;
end if;
end if;
end Null_Exclusion_Static_Checks;
----------------------------------
-- Conditional_Statements_Begin --
----------------------------------
procedure Conditional_Statements_Begin is
begin
Saved_Checks_TOS := Saved_Checks_TOS + 1;
-- If stack overflows, kill all checks, that way we know to simply reset
-- the number of saved checks to zero on return. This should never occur
-- in practice.
if Saved_Checks_TOS > Saved_Checks_Stack'Last then
Kill_All_Checks;
-- In the normal case, we just make a new stack entry saving the current
-- number of saved checks for a later restore.
else
Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
if Debug_Flag_CC then
w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
Num_Saved_Checks);
end if;
end if;
end Conditional_Statements_Begin;
--------------------------------
-- Conditional_Statements_End --
--------------------------------
procedure Conditional_Statements_End is
begin
pragma Assert (Saved_Checks_TOS > 0);
-- If the saved checks stack overflowed, then we killed all checks, so
-- setting the number of saved checks back to zero is correct. This
-- should never occur in practice.
if Saved_Checks_TOS > Saved_Checks_Stack'Last then
Num_Saved_Checks := 0;
-- In the normal case, restore the number of saved checks from the top
-- stack entry.
else
Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
if Debug_Flag_CC then
w ("Conditional_Statements_End: Num_Saved_Checks = ",
Num_Saved_Checks);
end if;
end if;
Saved_Checks_TOS := Saved_Checks_TOS - 1;
end Conditional_Statements_End;
-------------------------
-- Convert_From_Bignum --
-------------------------
function Convert_From_Bignum (N : Node_Id) return Node_Id is
Loc : constant Source_Ptr := Sloc (N);
begin
pragma Assert (Is_RTE (Etype (N), RE_Bignum));
-- Construct call From Bignum
return
Make_Function_Call (Loc,
Name =>
New_Occurrence_Of (RTE (RE_From_Bignum), Loc),
Parameter_Associations => New_List (Relocate_Node (N)));
end Convert_From_Bignum;
-----------------------
-- Convert_To_Bignum --
-----------------------
function Convert_To_Bignum (N : Node_Id) return Node_Id is
Loc : constant Source_Ptr := Sloc (N);
begin
-- Nothing to do if Bignum already except call Relocate_Node
if Is_RTE (Etype (N), RE_Bignum) then
return Relocate_Node (N);
-- Otherwise construct call to To_Bignum, converting the operand to the
-- required Long_Long_Integer form.
else
pragma Assert (Is_Signed_Integer_Type (Etype (N)));
return
Make_Function_Call (Loc,
Name =>
New_Occurrence_Of (RTE (RE_To_Bignum), Loc),
Parameter_Associations => New_List (
Convert_To (Standard_Long_Long_Integer, Relocate_Node (N))));
end if;
end Convert_To_Bignum;
---------------------
-- Determine_Range --
---------------------
Cache_Size : constant := 2 ** 10;
type Cache_Index is range 0 .. Cache_Size - 1;
-- Determine size of below cache (power of 2 is more efficient!)
Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
Determine_Range_Cache_V : array (Cache_Index) of Boolean;
Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
-- The above arrays are used to implement a small direct cache for
-- Determine_Range calls. Because of the way Determine_Range recursively
-- traces subexpressions, and because overflow checking calls the routine
-- on the way up the tree, a quadratic behavior can otherwise be
-- encountered in large expressions. The cache entry for node N is stored
-- in the (N mod Cache_Size) entry, and can be validated by checking the
-- actual node value stored there. The Range_Cache_V array records the
-- setting of Assume_Valid for the cache entry.
procedure Determine_Range
(N : Node_Id;
OK : out Boolean;
Lo : out Uint;
Hi : out Uint;
Assume_Valid : Boolean := False)
is
Typ : Entity_Id := Etype (N);
-- Type to use, may get reset to base type for possibly invalid entity
Lo_Left : Uint;
Hi_Left : Uint;
-- Lo and Hi bounds of left operand
Lo_Right : Uint;
Hi_Right : Uint;
-- Lo and Hi bounds of right (or only) operand
Bound : Node_Id;
-- Temp variable used to hold a bound node
Hbound : Uint;
-- High bound of base type of expression
Lor : Uint;
Hir : Uint;
-- Refined values for low and high bounds, after tightening
OK1 : Boolean;
-- Used in lower level calls to indicate if call succeeded
Cindex : Cache_Index;
-- Used to search cache
Btyp : Entity_Id;
-- Base type
function OK_Operands return Boolean;
-- Used for binary operators. Determines the ranges of the left and
-- right operands, and if they are both OK, returns True, and puts
-- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
-----------------
-- OK_Operands --
-----------------
function OK_Operands return Boolean is
begin
Determine_Range
(Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
if not OK1 then
return False;
end if;
Determine_Range
(Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
return OK1;
end OK_Operands;
-- Start of processing for Determine_Range
begin
-- For temporary constants internally generated to remove side effects
-- we must use the corresponding expression to determine the range of
-- the expression.
if Is_Entity_Name (N)
and then Nkind (Parent (Entity (N))) = N_Object_Declaration
and then Ekind (Entity (N)) = E_Constant
and then Is_Internal_Name (Chars (Entity (N)))
then
Determine_Range
(Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
return;
end if;
-- Prevent junk warnings by initializing range variables
Lo := No_Uint;
Hi := No_Uint;
Lor := No_Uint;
Hir := No_Uint;
-- If type is not defined, we can't determine its range
if No (Typ)
-- We don't deal with anything except discrete types
or else not Is_Discrete_Type (Typ)
-- Ignore type for which an error has been posted, since range in
-- this case may well be a bogosity deriving from the error. Also
-- ignore if error posted on the reference node.
or else Error_Posted (N) or else Error_Posted (Typ)
then
OK := False;
return;
end if;
-- For all other cases, we can determine the range
OK := True;
-- If value is compile time known, then the possible range is the one
-- value that we know this expression definitely has!
if Compile_Time_Known_Value (N) then
Lo := Expr_Value (N);
Hi := Lo;
return;
end if;
-- Return if already in the cache
Cindex := Cache_Index (N mod Cache_Size);
if Determine_Range_Cache_N (Cindex) = N
and then
Determine_Range_Cache_V (Cindex) = Assume_Valid
then
Lo := Determine_Range_Cache_Lo (Cindex);
Hi := Determine_Range_Cache_Hi (Cindex);
return;
end if;
-- Otherwise, start by finding the bounds of the type of the expression,
-- the value cannot be outside this range (if it is, then we have an
-- overflow situation, which is a separate check, we are talking here
-- only about the expression value).
-- First a check, never try to find the bounds of a generic type, since
-- these bounds are always junk values, and it is only valid to look at
-- the bounds in an instance.
if Is_Generic_Type (Typ) then
OK := False;
return;
end if;
-- First step, change to use base type unless we know the value is valid
if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
or else Assume_No_Invalid_Values
or else Assume_Valid
then
null;
else
Typ := Underlying_Type (Base_Type (Typ));
end if;
-- Retrieve the base type. Handle the case where the base type is a
-- private enumeration type.
Btyp := Base_Type (Typ);
if Is_Private_Type (Btyp) and then Present (Full_View (Btyp)) then
Btyp := Full_View (Btyp);
end if;
-- We use the actual bound unless it is dynamic, in which case use the
-- corresponding base type bound if possible. If we can't get a bound
-- then we figure we can't determine the range (a peculiar case, that
-- perhaps cannot happen, but there is no point in bombing in this
-- optimization circuit.
-- First the low bound
Bound := Type_Low_Bound (Typ);
if Compile_Time_Known_Value (Bound) then
Lo := Expr_Value (Bound);
elsif Compile_Time_Known_Value (Type_Low_Bound (Btyp)) then
Lo := Expr_Value (Type_Low_Bound (Btyp));
else
OK := False;
return;
end if;
-- Now the high bound
Bound := Type_High_Bound (Typ);
-- We need the high bound of the base type later on, and this should
-- always be compile time known. Again, it is not clear that this
-- can ever be false, but no point in bombing.
if Compile_Time_Known_Value (Type_High_Bound (Btyp)) then
Hbound := Expr_Value (Type_High_Bound (Btyp));
Hi := Hbound;
else
OK := False;
return;
end if;
-- If we have a static subtype, then that may have a tighter bound so
-- use the upper bound of the subtype instead in this case.
if Compile_Time_Known_Value (Bound) then
Hi := Expr_Value (Bound);
end if;
-- We may be able to refine this value in certain situations. If any
-- refinement is possible, then Lor and Hir are set to possibly tighter
-- bounds, and OK1 is set to True.
case Nkind (N) is
-- For unary plus, result is limited by range of operand
when N_Op_Plus =>
Determine_Range
(Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
-- For unary minus, determine range of operand, and negate it
when N_Op_Minus =>
Determine_Range
(Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
if OK1 then
Lor := -Hi_Right;
Hir := -Lo_Right;
end if;
-- For binary addition, get range of each operand and do the
-- addition to get the result range.
when N_Op_Add =>
if OK_Operands then
Lor := Lo_Left + Lo_Right;
Hir := Hi_Left + Hi_Right;
end if;
-- Division is tricky. The only case we consider is where the right
-- operand is a positive constant, and in this case we simply divide
-- the bounds of the left operand
when N_Op_Divide =>
if OK_Operands then
if Lo_Right = Hi_Right
and then Lo_Right > 0
then
Lor := Lo_Left / Lo_Right;
Hir := Hi_Left / Lo_Right;
else
OK1 := False;
end if;
end if;
-- For binary subtraction, get range of each operand and do the worst
-- case subtraction to get the result range.
when N_Op_Subtract =>
if OK_Operands then
Lor := Lo_Left - Hi_Right;
Hir := Hi_Left - Lo_Right;
end if;
-- For MOD, if right operand is a positive constant, then result must
-- be in the allowable range of mod results.
when N_Op_Mod =>
if OK_Operands then
if Lo_Right = Hi_Right
and then Lo_Right /= 0
then
if Lo_Right > 0 then
Lor := Uint_0;
Hir := Lo_Right - 1;
else -- Lo_Right < 0
Lor := Lo_Right + 1;
Hir := Uint_0;
end if;
else
OK1 := False;
end if;
end if;
-- For REM, if right operand is a positive constant, then result must
-- be in the allowable range of mod results.
when N_Op_Rem =>
if OK_Operands then
if Lo_Right = Hi_Right
and then Lo_Right /= 0
then
declare
Dval : constant Uint := (abs Lo_Right) - 1;
begin
-- The sign of the result depends on the sign of the
-- dividend (but not on the sign of the divisor, hence
-- the abs operation above).
if Lo_Left < 0 then
Lor := -Dval;
else
Lor := Uint_0;
end if;
if Hi_Left < 0 then
Hir := Uint_0;
else
Hir := Dval;
end if;
end;
else
OK1 := False;
end if;
end if;
-- Attribute reference cases
when N_Attribute_Reference =>
case Attribute_Name (N) is
-- For Pos/Val attributes, we can refine the range using the
-- possible range of values of the attribute expression.
when Name_Pos | Name_Val =>
Determine_Range
(First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
-- For Length attribute, use the bounds of the corresponding
-- index type to refine the range.
when Name_Length =>
declare
Atyp : Entity_Id := Etype (Prefix (N));
Inum : Nat;
Indx : Node_Id;
LL, LU : Uint;
UL, UU : Uint;
begin
if Is_Access_Type (Atyp) then
Atyp := Designated_Type (Atyp);
end if;
-- For string literal, we know exact value
if Ekind (Atyp) = E_String_Literal_Subtype then
OK := True;
Lo := String_Literal_Length (Atyp);
Hi := String_Literal_Length (Atyp);
return;
end if;
-- Otherwise check for expression given
if No (Expressions (N)) then
Inum := 1;
else
Inum :=
UI_To_Int (Expr_Value (First (Expressions (N))));
end if;
Indx := First_Index (Atyp);
for J in 2 .. Inum loop
Indx := Next_Index (Indx);
end loop;
-- If the index type is a formal type or derived from
-- one, the bounds are not static.
if Is_Generic_Type (Root_Type (Etype (Indx))) then
OK := False;
return;
end if;
Determine_Range
(Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
Assume_Valid);
if OK1 then
Determine_Range
(Type_High_Bound (Etype (Indx)), OK1, UL, UU,
Assume_Valid);
if OK1 then
-- The maximum value for Length is the biggest
-- possible gap between the values of the bounds.
-- But of course, this value cannot be negative.
Hir := UI_Max (Uint_0, UU - LL + 1);
-- For constrained arrays, the minimum value for
-- Length is taken from the actual value of the
-- bounds, since the index will be exactly of this
-- subtype.
if Is_Constrained (Atyp) then
Lor := UI_Max (Uint_0, UL - LU + 1);
-- For an unconstrained array, the minimum value
-- for length is always zero.
else
Lor := Uint_0;
end if;
end if;
end if;
end;
-- No special handling for other attributes
-- Probably more opportunities exist here???
when others =>
OK1 := False;
end case;
-- For type conversion from one discrete type to another, we can
-- refine the range using the converted value.
when N_Type_Conversion =>
Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
-- Nothing special to do for all other expression kinds
when others =>
OK1 := False;
Lor := No_Uint;
Hir := No_Uint;
end case;
-- At this stage, if OK1 is true, then we know that the actual result of
-- the computed expression is in the range Lor .. Hir. We can use this
-- to restrict the possible range of results.
if OK1 then
-- If the refined value of the low bound is greater than the type
-- high bound, then reset it to the more restrictive value. However,
-- we do NOT do this for the case of a modular type where the
-- possible upper bound on the value is above the base type high
-- bound, because that means the result could wrap.
if Lor > Lo
and then not (Is_Modular_Integer_Type (Typ) and then Hir > Hbound)
then
Lo := Lor;
end if;
-- Similarly, if the refined value of the high bound is less than the
-- value so far, then reset it to the more restrictive value. Again,
-- we do not do this if the refined low bound is negative for a
-- modular type, since this would wrap.
if Hir < Hi
and then not (Is_Modular_Integer_Type (Typ) and then Lor < Uint_0)
then
Hi := Hir;
end if;
end if;
-- Set cache entry for future call and we are all done
Determine_Range_Cache_N (Cindex) := N;
Determine_Range_Cache_V (Cindex) := Assume_Valid;
Determine_Range_Cache_Lo (Cindex) := Lo;
Determine_Range_Cache_Hi (Cindex) := Hi;
return;
-- If any exception occurs, it means that we have some bug in the compiler,
-- possibly triggered by a previous error, or by some unforeseen peculiar
-- occurrence. However, this is only an optimization attempt, so there is
-- really no point in crashing the compiler. Instead we just decide, too
-- bad, we can't figure out a range in this case after all.
exception
when others =>
-- Debug flag K disables this behavior (useful for debugging)
if Debug_Flag_K then
raise;
else
OK := False;
Lo := No_Uint;
Hi := No_Uint;
return;
end if;
end Determine_Range;
------------------------------------
-- Discriminant_Checks_Suppressed --
------------------------------------
function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) then
if Is_Unchecked_Union (E) then
return True;
elsif Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Discriminant_Check);
end if;
end if;
return Scope_Suppress.Suppress (Discriminant_Check);
end Discriminant_Checks_Suppressed;
--------------------------------
-- Division_Checks_Suppressed --
--------------------------------
function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Division_Check);
else
return Scope_Suppress.Suppress (Division_Check);
end if;
end Division_Checks_Suppressed;
-----------------------------------
-- Elaboration_Checks_Suppressed --
-----------------------------------
function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
-- The complication in this routine is that if we are in the dynamic
-- model of elaboration, we also check All_Checks, since All_Checks
-- does not set Elaboration_Check explicitly.
if Present (E) then
if Kill_Elaboration_Checks (E) then
return True;
elsif Checks_May_Be_Suppressed (E) then
if Is_Check_Suppressed (E, Elaboration_Check) then
return True;
elsif Dynamic_Elaboration_Checks then
return Is_Check_Suppressed (E, All_Checks);
else
return False;
end if;
end if;
end if;
if Scope_Suppress.Suppress (Elaboration_Check) then
return True;
elsif Dynamic_Elaboration_Checks then
return Scope_Suppress.Suppress (All_Checks);
else
return False;
end if;
end Elaboration_Checks_Suppressed;
---------------------------
-- Enable_Overflow_Check --
---------------------------
procedure Enable_Overflow_Check (N : Node_Id) is
Typ : constant Entity_Id := Base_Type (Etype (N));
Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
Chk : Nat;
OK : Boolean;
Ent : Entity_Id;
Ofs : Uint;
Lo : Uint;
Hi : Uint;
begin
if Debug_Flag_CC then
w ("Enable_Overflow_Check for node ", Int (N));
Write_Str (" Source location = ");
wl (Sloc (N));
pg (Union_Id (N));
end if;
-- No check if overflow checks suppressed for type of node
if Overflow_Checks_Suppressed (Etype (N)) then
return;
-- Nothing to do for unsigned integer types, which do not overflow
elsif Is_Modular_Integer_Type (Typ) then
return;
end if;
-- This is the point at which processing for STRICT mode diverges
-- from processing for MINIMIZED/ELIMINATED modes. This divergence is
-- probably more extreme that it needs to be, but what is going on here
-- is that when we introduced MINIMIZED/ELIMINATED modes, we wanted
-- to leave the processing for STRICT mode untouched. There were
-- two reasons for this. First it avoided any incompatible change of
-- behavior. Second, it guaranteed that STRICT mode continued to be
-- legacy reliable.
-- The big difference is that in STRICT mode there is a fair amount of
-- circuitry to try to avoid setting the Do_Overflow_Check flag if we
-- know that no check is needed. We skip all that in the two new modes,
-- since really overflow checking happens over a whole subtree, and we
-- do the corresponding optimizations later on when applying the checks.
if Mode in Minimized_Or_Eliminated then
if not (Overflow_Checks_Suppressed (Etype (N)))
and then not (Is_Entity_Name (N)
and then Overflow_Checks_Suppressed (Entity (N)))
then
Activate_Overflow_Check (N);
end if;
if Debug_Flag_CC then
w ("Minimized/Eliminated mode");
end if;
return;
end if;
-- Remainder of processing is for STRICT case, and is unchanged from
-- earlier versions preceding the addition of MINIMIZED/ELIMINATED.
-- Nothing to do if the range of the result is known OK. We skip this
-- for conversions, since the caller already did the check, and in any
-- case the condition for deleting the check for a type conversion is
-- different.
if Nkind (N) /= N_Type_Conversion then
Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
-- Note in the test below that we assume that the range is not OK
-- if a bound of the range is equal to that of the type. That's not
-- quite accurate but we do this for the following reasons:
-- a) The way that Determine_Range works, it will typically report
-- the bounds of the value as being equal to the bounds of the
-- type, because it either can't tell anything more precise, or
-- does not think it is worth the effort to be more precise.
-- b) It is very unusual to have a situation in which this would
-- generate an unnecessary overflow check (an example would be
-- a subtype with a range 0 .. Integer'Last - 1 to which the
-- literal value one is added).
-- c) The alternative is a lot of special casing in this routine
-- which would partially duplicate Determine_Range processing.
if OK
and then Lo > Expr_Value (Type_Low_Bound (Typ))
and then Hi < Expr_Value (Type_High_Bound (Typ))
then
if Debug_Flag_CC then
w ("No overflow check required");
end if;
return;
end if;
end if;
-- If not in optimizing mode, set flag and we are done. We are also done
-- (and just set the flag) if the type is not a discrete type, since it
-- is not worth the effort to eliminate checks for other than discrete
-- types. In addition, we take this same path if we have stored the
-- maximum number of checks possible already (a very unlikely situation,
-- but we do not want to blow up!)
if Optimization_Level = 0
or else not Is_Discrete_Type (Etype (N))
or else Num_Saved_Checks = Saved_Checks'Last
then
Activate_Overflow_Check (N);
if Debug_Flag_CC then
w ("Optimization off");
end if;
return;
end if;
-- Otherwise evaluate and check the expression
Find_Check
(Expr => N,
Check_Type => 'O',
Target_Type => Empty,
Entry_OK => OK,
Check_Num => Chk,
Ent => Ent,
Ofs => Ofs);
if Debug_Flag_CC then
w ("Called Find_Check");
w (" OK = ", OK);
if OK then
w (" Check_Num = ", Chk);
w (" Ent = ", Int (Ent));
Write_Str (" Ofs = ");
pid (Ofs);
end if;
end if;
-- If check is not of form to optimize, then set flag and we are done
if not OK then
Activate_Overflow_Check (N);
return;
end if;
-- If check is already performed, then return without setting flag
if Chk /= 0 then
if Debug_Flag_CC then
w ("Check suppressed!");
end if;
return;
end if;
-- Here we will make a new entry for the new check
Activate_Overflow_Check (N);
Num_Saved_Checks := Num_Saved_Checks + 1;
Saved_Checks (Num_Saved_Checks) :=
(Killed => False,
Entity => Ent,
Offset => Ofs,
Check_Type => 'O',
Target_Type => Empty);
if Debug_Flag_CC then
w ("Make new entry, check number = ", Num_Saved_Checks);
w (" Entity = ", Int (Ent));
Write_Str (" Offset = ");
pid (Ofs);
w (" Check_Type = O");
w (" Target_Type = Empty");
end if;
-- If we get an exception, then something went wrong, probably because of
-- an error in the structure of the tree due to an incorrect program. Or it
-- may be a bug in the optimization circuit. In either case the safest
-- thing is simply to set the check flag unconditionally.
exception
when others =>
Activate_Overflow_Check (N);
if Debug_Flag_CC then
w (" exception occurred, overflow flag set");
end if;
return;
end Enable_Overflow_Check;
------------------------
-- Enable_Range_Check --
------------------------
procedure Enable_Range_Check (N : Node_Id) is
Chk : Nat;
OK : Boolean;
Ent : Entity_Id;
Ofs : Uint;
Ttyp : Entity_Id;
P : Node_Id;
begin
-- Return if unchecked type conversion with range check killed. In this
-- case we never set the flag (that's what Kill_Range_Check is about!)
if Nkind (N) = N_Unchecked_Type_Conversion
and then Kill_Range_Check (N)
then
return;
end if;
-- Do not set range check flag if parent is assignment statement or
-- object declaration with Suppress_Assignment_Checks flag set
if Nkind_In (Parent (N), N_Assignment_Statement, N_Object_Declaration)
and then Suppress_Assignment_Checks (Parent (N))
then
return;
end if;
-- Check for various cases where we should suppress the range check
-- No check if range checks suppressed for type of node
if Present (Etype (N))
and then Range_Checks_Suppressed (Etype (N))
then
return;
-- No check if node is an entity name, and range checks are suppressed
-- for this entity, or for the type of this entity.
elsif Is_Entity_Name (N)
and then (Range_Checks_Suppressed (Entity (N))
or else Range_Checks_Suppressed (Etype (Entity (N))))
then
return;
-- No checks if index of array, and index checks are suppressed for
-- the array object or the type of the array.
elsif Nkind (Parent (N)) = N_Indexed_Component then
declare
Pref : constant Node_Id := Prefix (Parent (N));
begin
if Is_Entity_Name (Pref)
and then Index_Checks_Suppressed (Entity (Pref))
then
return;
elsif Index_Checks_Suppressed (Etype (Pref)) then
return;
end if;
end;
end if;
-- Debug trace output
if Debug_Flag_CC then
w ("Enable_Range_Check for node ", Int (N));
Write_Str (" Source location = ");
wl (Sloc (N));
pg (Union_Id (N));
end if;
-- If not in optimizing mode, set flag and we are done. We are also done
-- (and just set the flag) if the type is not a discrete type, since it
-- is not worth the effort to eliminate checks for other than discrete
-- types. In addition, we take this same path if we have stored the
-- maximum number of checks possible already (a very unlikely situation,
-- but we do not want to blow up!)
if Optimization_Level = 0
or else No (Etype (N))
or else not Is_Discrete_Type (Etype (N))
or else Num_Saved_Checks = Saved_Checks'Last
then
Activate_Range_Check (N);
if Debug_Flag_CC then
w ("Optimization off");
end if;
return;
end if;
-- Otherwise find out the target type
P := Parent (N);
-- For assignment, use left side subtype
if Nkind (P) = N_Assignment_Statement
and then Expression (P) = N
then
Ttyp := Etype (Name (P));
-- For indexed component, use subscript subtype
elsif Nkind (P) = N_Indexed_Component then
declare
Atyp : Entity_Id;
Indx : Node_Id;
Subs : Node_Id;
begin
Atyp := Etype (Prefix (P));
if Is_Access_Type (Atyp) then
Atyp := Designated_Type (Atyp);
-- If the prefix is an access to an unconstrained array,
-- perform check unconditionally: it depends on the bounds of
-- an object and we cannot currently recognize whether the test
-- may be redundant.
if not Is_Constrained (Atyp) then
Activate_Range_Check (N);
return;
end if;
-- Ditto if the prefix is an explicit dereference whose designated
-- type is unconstrained.
elsif Nkind (Prefix (P)) = N_Explicit_Dereference
and then not Is_Constrained (Atyp)
then
Activate_Range_Check (N);
return;
end if;
Indx := First_Index (Atyp);
Subs := First (Expressions (P));
loop
if Subs = N then
Ttyp := Etype (Indx);
exit;
end if;
Next_Index (Indx);
Next (Subs);
end loop;
end;
-- For now, ignore all other cases, they are not so interesting
else
if Debug_Flag_CC then
w (" target type not found, flag set");
end if;
Activate_Range_Check (N);
return;
end if;
-- Evaluate and check the expression
Find_Check
(Expr => N,
Check_Type => 'R',
Target_Type => Ttyp,
Entry_OK => OK,
Check_Num => Chk,
Ent => Ent,
Ofs => Ofs);
if Debug_Flag_CC then
w ("Called Find_Check");
w ("Target_Typ = ", Int (Ttyp));
w (" OK = ", OK);
if OK then
w (" Check_Num = ", Chk);
w (" Ent = ", Int (Ent));
Write_Str (" Ofs = ");
pid (Ofs);
end if;
end if;
-- If check is not of form to optimize, then set flag and we are done
if not OK then
if Debug_Flag_CC then
w (" expression not of optimizable type, flag set");
end if;
Activate_Range_Check (N);
return;
end if;
-- If check is already performed, then return without setting flag
if Chk /= 0 then
if Debug_Flag_CC then
w ("Check suppressed!");
end if;
return;
end if;
-- Here we will make a new entry for the new check
Activate_Range_Check (N);
Num_Saved_Checks := Num_Saved_Checks + 1;
Saved_Checks (Num_Saved_Checks) :=
(Killed => False,
Entity => Ent,
Offset => Ofs,
Check_Type => 'R',
Target_Type => Ttyp);
if Debug_Flag_CC then
w ("Make new entry, check number = ", Num_Saved_Checks);
w (" Entity = ", Int (Ent));
Write_Str (" Offset = ");
pid (Ofs);
w (" Check_Type = R");
w (" Target_Type = ", Int (Ttyp));
pg (Union_Id (Ttyp));
end if;
-- If we get an exception, then something went wrong, probably because of
-- an error in the structure of the tree due to an incorrect program. Or
-- it may be a bug in the optimization circuit. In either case the safest
-- thing is simply to set the check flag unconditionally.
exception
when others =>
Activate_Range_Check (N);
if Debug_Flag_CC then
w (" exception occurred, range flag set");
end if;
return;
end Enable_Range_Check;
------------------
-- Ensure_Valid --
------------------
procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
Typ : constant Entity_Id := Etype (Expr);
begin
-- Ignore call if we are not doing any validity checking
if not Validity_Checks_On then
return;
-- Ignore call if range or validity checks suppressed on entity or type
elsif Range_Or_Validity_Checks_Suppressed (Expr) then
return;
-- No check required if expression is from the expander, we assume the
-- expander will generate whatever checks are needed. Note that this is
-- not just an optimization, it avoids infinite recursions!
-- Unchecked conversions must be checked, unless they are initialized
-- scalar values, as in a component assignment in an init proc.
-- In addition, we force a check if Force_Validity_Checks is set
elsif not Comes_From_Source (Expr)
and then not Force_Validity_Checks
and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
or else Kill_Range_Check (Expr))
then
return;
-- No check required if expression is known to have valid value
elsif Expr_Known_Valid (Expr) then
return;
-- Ignore case of enumeration with holes where the flag is set not to
-- worry about holes, since no special validity check is needed
elsif Is_Enumeration_Type (Typ)
and then Has_Non_Standard_Rep (Typ)
and then Holes_OK
then
return;
-- No check required on the left-hand side of an assignment
elsif Nkind (Parent (Expr)) = N_Assignment_Statement
and then Expr = Name (Parent (Expr))
then
return;
-- No check on a universal real constant. The context will eventually
-- convert it to a machine number for some target type, or report an
-- illegality.
elsif Nkind (Expr) = N_Real_Literal
and then Etype (Expr) = Universal_Real
then
return;
-- If the expression denotes a component of a packed boolean array,
-- no possible check applies. We ignore the old ACATS chestnuts that
-- involve Boolean range True..True.
-- Note: validity checks are generated for expressions that yield a
-- scalar type, when it is possible to create a value that is outside of
-- the type. If this is a one-bit boolean no such value exists. This is
-- an optimization, and it also prevents compiler blowing up during the
-- elaboration of improperly expanded packed array references.
elsif Nkind (Expr) = N_Indexed_Component
and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
and then Root_Type (Etype (Expr)) = Standard_Boolean
then
return;
-- An annoying special case. If this is an out parameter of a scalar
-- type, then the value is not going to be accessed, therefore it is
-- inappropriate to do any validity check at the call site.
else
-- Only need to worry about scalar types
if Is_Scalar_Type (Typ) then
declare
P : Node_Id;
N : Node_Id;
E : Entity_Id;
F : Entity_Id;
A : Node_Id;
L : List_Id;
begin
-- Find actual argument (which may be a parameter association)
-- and the parent of the actual argument (the call statement)
N := Expr;
P := Parent (Expr);
if Nkind (P) = N_Parameter_Association then
N := P;
P := Parent (N);
end if;
-- Only need to worry if we are argument of a procedure call
-- since functions don't have out parameters. If this is an
-- indirect or dispatching call, get signature from the
-- subprogram type.
if Nkind (P) = N_Procedure_Call_Statement then
L := Parameter_Associations (P);
if Is_Entity_Name (Name (P)) then
E := Entity (Name (P));
else
pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
E := Etype (Name (P));
end if;
-- Only need to worry if there are indeed actuals, and if
-- this could be a procedure call, otherwise we cannot get a
-- match (either we are not an argument, or the mode of the
-- formal is not OUT). This test also filters out the
-- generic case.
if Is_Non_Empty_List (L)
and then Is_Subprogram (E)
then
-- This is the loop through parameters, looking for an
-- OUT parameter for which we are the argument.
F := First_Formal (E);
A := First (L);
while Present (F) loop
if Ekind (F) = E_Out_Parameter and then A = N then
return;
end if;
Next_Formal (F);
Next (A);
end loop;
end if;
end if;
end;
end if;
end if;
-- If this is a boolean expression, only its elementary operands need
-- checking: if they are valid, a boolean or short-circuit operation
-- with them will be valid as well.
if Base_Type (Typ) = Standard_Boolean
and then
(Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit)
then
return;
end if;
-- If we fall through, a validity check is required
Insert_Valid_Check (Expr);
if Is_Entity_Name (Expr)
and then Safe_To_Capture_Value (Expr, Entity (Expr))
then
Set_Is_Known_Valid (Entity (Expr));
end if;
end Ensure_Valid;
----------------------
-- Expr_Known_Valid --
----------------------
function Expr_Known_Valid (Expr : Node_Id) return Boolean is
Typ : constant Entity_Id := Etype (Expr);
begin
-- Non-scalar types are always considered valid, since they never give
-- rise to the issues of erroneous or bounded error behavior that are
-- the concern. In formal reference manual terms the notion of validity
-- only applies to scalar types. Note that even when packed arrays are
-- represented using modular types, they are still arrays semantically,
-- so they are also always valid (in particular, the unused bits can be
-- random rubbish without affecting the validity of the array value).
if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
return True;
-- If no validity checking, then everything is considered valid
elsif not Validity_Checks_On then
return True;
-- Floating-point types are considered valid unless floating-point
-- validity checks have been specifically turned on.
elsif Is_Floating_Point_Type (Typ)
and then not Validity_Check_Floating_Point
then
return True;
-- If the expression is the value of an object that is known to be
-- valid, then clearly the expression value itself is valid.
elsif Is_Entity_Name (Expr)
and then Is_Known_Valid (Entity (Expr))
then
return True;
-- References to discriminants are always considered valid. The value
-- of a discriminant gets checked when the object is built. Within the
-- record, we consider it valid, and it is important to do so, since
-- otherwise we can try to generate bogus validity checks which
-- reference discriminants out of scope. Discriminants of concurrent
-- types are excluded for the same reason.
elsif Is_Entity_Name (Expr)
and then Denotes_Discriminant (Expr, Check_Concurrent => True)
then
return True;
-- If the type is one for which all values are known valid, then we are
-- sure that the value is valid except in the slightly odd case where
-- the expression is a reference to a variable whose size has been
-- explicitly set to a value greater than the object size.
elsif Is_Known_Valid (Typ) then
if Is_Entity_Name (Expr)
and then Ekind (Entity (Expr)) = E_Variable
and then Esize (Entity (Expr)) > Esize (Typ)
then
return False;
else
return True;
end if;
-- Integer and character literals always have valid values, where
-- appropriate these will be range checked in any case.
elsif Nkind (Expr) = N_Integer_Literal
or else
Nkind (Expr) = N_Character_Literal
then
return True;
-- Real literals are assumed to be valid in VM targets
elsif VM_Target /= No_VM
and then Nkind (Expr) = N_Real_Literal
then
return True;
-- If we have a type conversion or a qualification of a known valid
-- value, then the result will always be valid.
elsif Nkind (Expr) = N_Type_Conversion
or else
Nkind (Expr) = N_Qualified_Expression
then
return Expr_Known_Valid (Expression (Expr));
-- The result of any operator is always considered valid, since we
-- assume the necessary checks are done by the operator. For operators
-- on floating-point operations, we must also check when the operation
-- is the right-hand side of an assignment, or is an actual in a call.
elsif Nkind (Expr) in N_Op then
if Is_Floating_Point_Type (Typ)
and then Validity_Check_Floating_Point
and then
(Nkind (Parent (Expr)) = N_Assignment_Statement
or else Nkind (Parent (Expr)) = N_Function_Call
or else Nkind (Parent (Expr)) = N_Parameter_Association)
then
return False;
else
return True;
end if;
-- The result of a membership test is always valid, since it is true or
-- false, there are no other possibilities.
elsif Nkind (Expr) in N_Membership_Test then
return True;
-- For all other cases, we do not know the expression is valid
else
return False;
end if;
end Expr_Known_Valid;
----------------
-- Find_Check --
----------------
procedure Find_Check
(Expr : Node_Id;
Check_Type : Character;
Target_Type : Entity_Id;
Entry_OK : out Boolean;
Check_Num : out Nat;
Ent : out Entity_Id;
Ofs : out Uint)
is
function Within_Range_Of
(Target_Type : Entity_Id;
Check_Type : Entity_Id) return Boolean;
-- Given a requirement for checking a range against Target_Type, and
-- and a range Check_Type against which a check has already been made,
-- determines if the check against check type is sufficient to ensure
-- that no check against Target_Type is required.
---------------------
-- Within_Range_Of --
---------------------
function Within_Range_Of
(Target_Type : Entity_Id;
Check_Type : Entity_Id) return Boolean
is
begin
if Target_Type = Check_Type then
return True;
else
declare
Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
Thi : constant Node_Id := Type_High_Bound (Target_Type);
Clo : constant Node_Id := Type_Low_Bound (Check_Type);
Chi : constant Node_Id := Type_High_Bound (Check_Type);
begin
if (Tlo = Clo
or else (Compile_Time_Known_Value (Tlo)
and then
Compile_Time_Known_Value (Clo)
and then
Expr_Value (Clo) >= Expr_Value (Tlo)))
and then
(Thi = Chi
or else (Compile_Time_Known_Value (Thi)
and then
Compile_Time_Known_Value (Chi)
and then
Expr_Value (Chi) <= Expr_Value (Clo)))
then
return True;
else
return False;
end if;
end;
end if;
end Within_Range_Of;
-- Start of processing for Find_Check
begin
-- Establish default, in case no entry is found
Check_Num := 0;
-- Case of expression is simple entity reference
if Is_Entity_Name (Expr) then
Ent := Entity (Expr);
Ofs := Uint_0;
-- Case of expression is entity + known constant
elsif Nkind (Expr) = N_Op_Add
and then Compile_Time_Known_Value (Right_Opnd (Expr))
and then Is_Entity_Name (Left_Opnd (Expr))
then
Ent := Entity (Left_Opnd (Expr));
Ofs := Expr_Value (Right_Opnd (Expr));
-- Case of expression is entity - known constant
elsif Nkind (Expr) = N_Op_Subtract
and then Compile_Time_Known_Value (Right_Opnd (Expr))
and then Is_Entity_Name (Left_Opnd (Expr))
then
Ent := Entity (Left_Opnd (Expr));
Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
-- Any other expression is not of the right form
else
Ent := Empty;
Ofs := Uint_0;
Entry_OK := False;
return;
end if;
-- Come here with expression of appropriate form, check if entity is an
-- appropriate one for our purposes.
if (Ekind (Ent) = E_Variable
or else Is_Constant_Object (Ent))
and then not Is_Library_Level_Entity (Ent)
then
Entry_OK := True;
else
Entry_OK := False;
return;
end if;
-- See if there is matching check already
for J in reverse 1 .. Num_Saved_Checks loop
declare
SC : Saved_Check renames Saved_Checks (J);
begin
if SC.Killed = False
and then SC.Entity = Ent
and then SC.Offset = Ofs
and then SC.Check_Type = Check_Type
and then Within_Range_Of (Target_Type, SC.Target_Type)
then
Check_Num := J;
return;
end if;
end;
end loop;
-- If we fall through entry was not found
return;
end Find_Check;
---------------------------------
-- Generate_Discriminant_Check --
---------------------------------
-- Note: the code for this procedure is derived from the
-- Emit_Discriminant_Check Routine in trans.c.
procedure Generate_Discriminant_Check (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Pref : constant Node_Id := Prefix (N);
Sel : constant Node_Id := Selector_Name (N);
Orig_Comp : constant Entity_Id :=
Original_Record_Component (Entity (Sel));
-- The original component to be checked
Discr_Fct : constant Entity_Id :=
Discriminant_Checking_Func (Orig_Comp);
-- The discriminant checking function
Discr : Entity_Id;
-- One discriminant to be checked in the type
Real_Discr : Entity_Id;
-- Actual discriminant in the call
Pref_Type : Entity_Id;
-- Type of relevant prefix (ignoring private/access stuff)
Args : List_Id;
-- List of arguments for function call
Formal : Entity_Id;
-- Keep track of the formal corresponding to the actual we build for
-- each discriminant, in order to be able to perform the necessary type
-- conversions.
Scomp : Node_Id;
-- Selected component reference for checking function argument
begin
Pref_Type := Etype (Pref);
-- Force evaluation of the prefix, so that it does not get evaluated
-- twice (once for the check, once for the actual reference). Such a
-- double evaluation is always a potential source of inefficiency,
-- and is functionally incorrect in the volatile case, or when the
-- prefix may have side-effects. An entity or a component of an
-- entity requires no evaluation.
if Is_Entity_Name (Pref) then
if Treat_As_Volatile (Entity (Pref)) then
Force_Evaluation (Pref, Name_Req => True);
end if;
elsif Treat_As_Volatile (Etype (Pref)) then
Force_Evaluation (Pref, Name_Req => True);
elsif Nkind (Pref) = N_Selected_Component
and then Is_Entity_Name (Prefix (Pref))
then
null;
else
Force_Evaluation (Pref, Name_Req => True);
end if;
-- For a tagged type, use the scope of the original component to
-- obtain the type, because ???
if Is_Tagged_Type (Scope (Orig_Comp)) then
Pref_Type := Scope (Orig_Comp);
-- For an untagged derived type, use the discriminants of the parent
-- which have been renamed in the derivation, possibly by a one-to-many
-- discriminant constraint. For non-tagged type, initially get the Etype
-- of the prefix
else
if Is_Derived_Type (Pref_Type)
and then Number_Discriminants (Pref_Type) /=
Number_Discriminants (Etype (Base_Type (Pref_Type)))
then
Pref_Type := Etype (Base_Type (Pref_Type));
end if;
end if;
-- We definitely should have a checking function, This routine should
-- not be called if no discriminant checking function is present.
pragma Assert (Present (Discr_Fct));
-- Create the list of the actual parameters for the call. This list
-- is the list of the discriminant fields of the record expression to
-- be discriminant checked.
Args := New_List;
Formal := First_Formal (Discr_Fct);
Discr := First_Discriminant (Pref_Type);
while Present (Discr) loop
-- If we have a corresponding discriminant field, and a parent
-- subtype is present, then we want to use the corresponding
-- discriminant since this is the one with the useful value.
if Present (Corresponding_Discriminant (Discr))
and then Ekind (Pref_Type) = E_Record_Type
and then Present (Parent_Subtype (Pref_Type))
then
Real_Discr := Corresponding_Discriminant (Discr);
else
Real_Discr := Discr;
end if;
-- Construct the reference to the discriminant
Scomp :=
Make_Selected_Component (Loc,
Prefix =>
Unchecked_Convert_To (Pref_Type,
Duplicate_Subexpr (Pref)),
Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
-- Manually analyze and resolve this selected component. We really
-- want it just as it appears above, and do not want the expander
-- playing discriminal games etc with this reference. Then we append
-- the argument to the list we are gathering.
Set_Etype (Scomp, Etype (Real_Discr));
Set_Analyzed (Scomp, True);
Append_To (Args, Convert_To (Etype (Formal), Scomp));
Next_Formal_With_Extras (Formal);
Next_Discriminant (Discr);
end loop;
-- Now build and insert the call
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Function_Call (Loc,
Name => New_Occurrence_Of (Discr_Fct, Loc),
Parameter_Associations => Args),
Reason => CE_Discriminant_Check_Failed));
end Generate_Discriminant_Check;
---------------------------
-- Generate_Index_Checks --
---------------------------
procedure Generate_Index_Checks (N : Node_Id) is
function Entity_Of_Prefix return Entity_Id;
-- Returns the entity of the prefix of N (or Empty if not found)
----------------------
-- Entity_Of_Prefix --
----------------------
function Entity_Of_Prefix return Entity_Id is
P : Node_Id;
begin
P := Prefix (N);
while not Is_Entity_Name (P) loop
if not Nkind_In (P, N_Selected_Component,
N_Indexed_Component)
then
return Empty;
end if;
P := Prefix (P);
end loop;
return Entity (P);
end Entity_Of_Prefix;
-- Local variables
Loc : constant Source_Ptr := Sloc (N);
A : constant Node_Id := Prefix (N);
A_Ent : constant Entity_Id := Entity_Of_Prefix;
Sub : Node_Id;
-- Start of processing for Generate_Index_Checks
begin
-- Ignore call if the prefix is not an array since we have a serious
-- error in the sources. Ignore it also if index checks are suppressed
-- for array object or type.
if not Is_Array_Type (Etype (A))
or else (Present (A_Ent)
and then Index_Checks_Suppressed (A_Ent))
or else Index_Checks_Suppressed (Etype (A))
then
return;
-- The indexed component we are dealing with contains 'Loop_Entry in its
-- prefix. This case arises when analysis has determined that constructs
-- such as
-- Prefix'Loop_Entry (Expr)
-- Prefix'Loop_Entry (Expr1, Expr2, ... ExprN)
-- require rewriting for error detection purposes. A side effect of this
-- action is the generation of index checks that mention 'Loop_Entry.
-- Delay the generation of the check until 'Loop_Entry has been properly
-- expanded. This is done in Expand_Loop_Entry_Attributes.
elsif Nkind (Prefix (N)) = N_Attribute_Reference
and then Attribute_Name (Prefix (N)) = Name_Loop_Entry
then
return;
end if;
-- Generate a raise of constraint error with the appropriate reason and
-- a condition of the form:
-- Base_Type (Sub) not in Array'Range (Subscript)
-- Note that the reason we generate the conversion to the base type here
-- is that we definitely want the range check to take place, even if it
-- looks like the subtype is OK. Optimization considerations that allow
-- us to omit the check have already been taken into account in the
-- setting of the Do_Range_Check flag earlier on.
Sub := First (Expressions (N));
-- Handle string literals
if Ekind (Etype (A)) = E_String_Literal_Subtype then
if Do_Range_Check (Sub) then
Set_Do_Range_Check (Sub, False);
-- For string literals we obtain the bounds of the string from the
-- associated subtype.
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd =>
Convert_To (Base_Type (Etype (Sub)),
Duplicate_Subexpr_Move_Checks (Sub)),
Right_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => New_Reference_To (Etype (A), Loc),
Attribute_Name => Name_Range)),
Reason => CE_Index_Check_Failed));
end if;
-- General case
else
declare
A_Idx : Node_Id := Empty;
A_Range : Node_Id;
Ind : Nat;
Num : List_Id;
Range_N : Node_Id;
begin
A_Idx := First_Index (Etype (A));
Ind := 1;
while Present (Sub) loop
if Do_Range_Check (Sub) then
Set_Do_Range_Check (Sub, False);
-- Force evaluation except for the case of a simple name of
-- a non-volatile entity.
if not Is_Entity_Name (Sub)
or else Treat_As_Volatile (Entity (Sub))
then
Force_Evaluation (Sub);
end if;
if Nkind (A_Idx) = N_Range then
A_Range := A_Idx;
elsif Nkind (A_Idx) = N_Identifier
or else Nkind (A_Idx) = N_Expanded_Name
then
A_Range := Scalar_Range (Entity (A_Idx));
else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication);
A_Range := Range_Expression (Constraint (A_Idx));
end if;
-- For array objects with constant bounds we can generate
-- the index check using the bounds of the type of the index
if Present (A_Ent)
and then Ekind (A_Ent) = E_Variable
and then Is_Constant_Bound (Low_Bound (A_Range))
and then Is_Constant_Bound (High_Bound (A_Range))
then
Range_N :=
Make_Attribute_Reference (Loc,
Prefix =>
New_Reference_To (Etype (A_Idx), Loc),
Attribute_Name => Name_Range);
-- For arrays with non-constant bounds we cannot generate
-- the index check using the bounds of the type of the index
-- since it may reference discriminants of some enclosing
-- type. We obtain the bounds directly from the prefix
-- object.
else
if Ind = 1 then
Num := No_List;
else
Num := New_List (Make_Integer_Literal (Loc, Ind));
end if;
Range_N :=
Make_Attribute_Reference (Loc,
Prefix =>
Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
Attribute_Name => Name_Range,
Expressions => Num);
end if;
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd =>
Convert_To (Base_Type (Etype (Sub)),
Duplicate_Subexpr_Move_Checks (Sub)),
Right_Opnd => Range_N),
Reason => CE_Index_Check_Failed));
end if;
A_Idx := Next_Index (A_Idx);
Ind := Ind + 1;
Next (Sub);
end loop;
end;
end if;
end Generate_Index_Checks;
--------------------------
-- Generate_Range_Check --
--------------------------
procedure Generate_Range_Check
(N : Node_Id;
Target_Type : Entity_Id;
Reason : RT_Exception_Code)
is
Loc : constant Source_Ptr := Sloc (N);
Source_Type : constant Entity_Id := Etype (N);
Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
begin
-- First special case, if the source type is already within the range
-- of the target type, then no check is needed (probably we should have
-- stopped Do_Range_Check from being set in the first place, but better
-- late than never in preventing junk code!
if In_Subrange_Of (Source_Type, Target_Type)
-- We do NOT apply this if the source node is a literal, since in this
-- case the literal has already been labeled as having the subtype of
-- the target.
and then not
(Nkind_In (N, N_Integer_Literal, N_Real_Literal, N_Character_Literal)
or else
(Is_Entity_Name (N)
and then Ekind (Entity (N)) = E_Enumeration_Literal))
-- Also do not apply this for floating-point if Check_Float_Overflow
and then not
(Is_Floating_Point_Type (Source_Type) and Check_Float_Overflow)
then
return;
end if;
-- We need a check, so force evaluation of the node, so that it does
-- not get evaluated twice (once for the check, once for the actual
-- reference). Such a double evaluation is always a potential source
-- of inefficiency, and is functionally incorrect in the volatile case.
if not Is_Entity_Name (N) or else Treat_As_Volatile (Entity (N)) then
Force_Evaluation (N);
end if;
-- The easiest case is when Source_Base_Type and Target_Base_Type are
-- the same since in this case we can simply do a direct check of the
-- value of N against the bounds of Target_Type.
-- [constraint_error when N not in Target_Type]
-- Note: this is by far the most common case, for example all cases of
-- checks on the RHS of assignments are in this category, but not all
-- cases are like this. Notably conversions can involve two types.
if Source_Base_Type = Target_Base_Type then
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
Reason => Reason));
-- Next test for the case where the target type is within the bounds
-- of the base type of the source type, since in this case we can
-- simply convert these bounds to the base type of T to do the test.
-- [constraint_error when N not in
-- Source_Base_Type (Target_Type'First)
-- ..
-- Source_Base_Type(Target_Type'Last))]
-- The conversions will always work and need no check
-- Unchecked_Convert_To is used instead of Convert_To to handle the case
-- of converting from an enumeration value to an integer type, such as
-- occurs for the case of generating a range check on Enum'Val(Exp)
-- (which used to be handled by gigi). This is OK, since the conversion
-- itself does not require a check.
elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd =>
Make_Range (Loc,
Low_Bound =>
Unchecked_Convert_To (Source_Base_Type,
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_First)),
High_Bound =>
Unchecked_Convert_To (Source_Base_Type,
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_Last)))),
Reason => Reason));
-- Note that at this stage we now that the Target_Base_Type is not in
-- the range of the Source_Base_Type (since even the Target_Type itself
-- is not in this range). It could still be the case that Source_Type is
-- in range of the target base type since we have not checked that case.
-- If that is the case, we can freely convert the source to the target,
-- and then test the target result against the bounds.
elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
-- We make a temporary to hold the value of the converted value
-- (converted to the base type), and then we will do the test against
-- this temporary.
-- Tnn : constant Target_Base_Type := Target_Base_Type (N);
-- [constraint_error when Tnn not in Target_Type]
-- Then the conversion itself is replaced by an occurrence of Tnn
declare
Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
begin
Insert_Actions (N, New_List (
Make_Object_Declaration (Loc,
Defining_Identifier => Tnn,
Object_Definition =>
New_Occurrence_Of (Target_Base_Type, Loc),
Constant_Present => True,
Expression =>
Make_Type_Conversion (Loc,
Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
Expression => Duplicate_Subexpr (N))),
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Not_In (Loc,
Left_Opnd => New_Occurrence_Of (Tnn, Loc),
Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
Reason => Reason)));
Rewrite (N, New_Occurrence_Of (Tnn, Loc));
-- Set the type of N, because the declaration for Tnn might not
-- be analyzed yet, as is the case if N appears within a record
-- declaration, as a discriminant constraint or expression.
Set_Etype (N, Target_Base_Type);
end;
-- At this stage, we know that we have two scalar types, which are
-- directly convertible, and where neither scalar type has a base
-- range that is in the range of the other scalar type.
-- The only way this can happen is with a signed and unsigned type.
-- So test for these two cases:
else
-- Case of the source is unsigned and the target is signed
if Is_Unsigned_Type (Source_Base_Type)
and then not Is_Unsigned_Type (Target_Base_Type)
then
-- If the source is unsigned and the target is signed, then we
-- know that the source is not shorter than the target (otherwise
-- the source base type would be in the target base type range).
-- In other words, the unsigned type is either the same size as
-- the target, or it is larger. It cannot be smaller.
pragma Assert
(Esize (Source_Base_Type) >= Esize (Target_Base_Type));
-- We only need to check the low bound if the low bound of the
-- target type is non-negative. If the low bound of the target
-- type is negative, then we know that we will fit fine.
-- If the high bound of the target type is negative, then we
-- know we have a constraint error, since we can't possibly
-- have a negative source.
-- With these two checks out of the way, we can do the check
-- using the source type safely
-- This is definitely the most annoying case!
-- [constraint_error
-- when (Target_Type'First >= 0
-- and then
-- N < Source_Base_Type (Target_Type'First))
-- or else Target_Type'Last < 0
-- or else N > Source_Base_Type (Target_Type'Last)];
-- We turn off all checks since we know that the conversions
-- will work fine, given the guards for negative values.
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Or_Else (Loc,
Make_Or_Else (Loc,
Left_Opnd =>
Make_And_Then (Loc,
Left_Opnd => Make_Op_Ge (Loc,
Left_Opnd =>
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_First),
Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
Right_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd =>
Convert_To (Source_Base_Type,
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_First)))),
Right_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_Last),
Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
Right_Opnd =>
Make_Op_Gt (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd =>
Convert_To (Source_Base_Type,
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Target_Type, Loc),
Attribute_Name => Name_Last)))),
Reason => Reason),
Suppress => All_Checks);
-- Only remaining possibility is that the source is signed and
-- the target is unsigned.
else
pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
and then Is_Unsigned_Type (Target_Base_Type));
-- If the source is signed and the target is unsigned, then we
-- know that the target is not shorter than the source (otherwise
-- the target base type would be in the source base type range).
-- In other words, the unsigned type is either the same size as
-- the target, or it is larger. It cannot be smaller.
-- Clearly we have an error if the source value is negative since
-- no unsigned type can have negative values. If the source type
-- is non-negative, then the check can be done using the target
-- type.
-- Tnn : constant Target_Base_Type (N) := Target_Type;
-- [constraint_error
-- when N < 0 or else Tnn not in Target_Type];
-- We turn off all checks for the conversion of N to the target
-- base type, since we generate the explicit check to ensure that
-- the value is non-negative
declare
Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
begin
Insert_Actions (N, New_List (
Make_Object_Declaration (Loc,
Defining_Identifier => Tnn,
Object_Definition =>
New_Occurrence_Of (Target_Base_Type, Loc),
Constant_Present => True,
Expression =>
Make_Unchecked_Type_Conversion (Loc,
Subtype_Mark =>
New_Occurrence_Of (Target_Base_Type, Loc),
Expression => Duplicate_Subexpr (N))),
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Or_Else (Loc,
Left_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd => Duplicate_Subexpr (N),
Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
Right_Opnd =>
Make_Not_In (Loc,
Left_Opnd => New_Occurrence_Of (Tnn, Loc),
Right_Opnd =>
New_Occurrence_Of (Target_Type, Loc))),
Reason => Reason)),
Suppress => All_Checks);
-- Set the Etype explicitly, because Insert_Actions may have
-- placed the declaration in the freeze list for an enclosing
-- construct, and thus it is not analyzed yet.
Set_Etype (Tnn, Target_Base_Type);
Rewrite (N, New_Occurrence_Of (Tnn, Loc));
end;
end if;
end if;
end Generate_Range_Check;
------------------
-- Get_Check_Id --
------------------
function Get_Check_Id (N : Name_Id) return Check_Id is
begin
-- For standard check name, we can do a direct computation
if N in First_Check_Name .. Last_Check_Name then
return Check_Id (N - (First_Check_Name - 1));
-- For non-standard names added by pragma Check_Name, search table
else
for J in All_Checks + 1 .. Check_Names.Last loop
if Check_Names.Table (J) = N then
return J;
end if;
end loop;
end if;
-- No matching name found
return No_Check_Id;
end Get_Check_Id;
---------------------
-- Get_Discriminal --
---------------------
function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
Loc : constant Source_Ptr := Sloc (E);
D : Entity_Id;
Sc : Entity_Id;
begin
-- The bound can be a bona fide parameter of a protected operation,
-- rather than a prival encoded as an in-parameter.
if No (Discriminal_Link (Entity (Bound))) then
return Bound;
end if;
-- Climb the scope stack looking for an enclosing protected type. If
-- we run out of scopes, return the bound itself.
Sc := Scope (E);
while Present (Sc) loop
if Sc = Standard_Standard then
return Bound;
elsif Ekind (Sc) = E_Protected_Type then
exit;
end if;
Sc := Scope (Sc);
end loop;
D := First_Discriminant (Sc);
while Present (D) loop
if Chars (D) = Chars (Bound) then
return New_Occurrence_Of (Discriminal (D), Loc);
end if;
Next_Discriminant (D);
end loop;
return Bound;
end Get_Discriminal;
----------------------
-- Get_Range_Checks --
----------------------
function Get_Range_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id := Empty;
Warn_Node : Node_Id := Empty) return Check_Result
is
begin
return Selected_Range_Checks
(Ck_Node, Target_Typ, Source_Typ, Warn_Node);
end Get_Range_Checks;
------------------
-- Guard_Access --
------------------
function Guard_Access
(Cond : Node_Id;
Loc : Source_Ptr;
Ck_Node : Node_Id) return Node_Id
is
begin
if Nkind (Cond) = N_Or_Else then
Set_Paren_Count (Cond, 1);
end if;
if Nkind (Ck_Node) = N_Allocator then
return Cond;
else
return
Make_And_Then (Loc,
Left_Opnd =>
Make_Op_Ne (Loc,
Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
Right_Opnd => Make_Null (Loc)),
Right_Opnd => Cond);
end if;
end Guard_Access;
-----------------------------
-- Index_Checks_Suppressed --
-----------------------------
function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Index_Check);
else
return Scope_Suppress.Suppress (Index_Check);
end if;
end Index_Checks_Suppressed;
----------------
-- Initialize --
----------------
procedure Initialize is
begin
for J in Determine_Range_Cache_N'Range loop
Determine_Range_Cache_N (J) := Empty;
end loop;
Check_Names.Init;
for J in Int range 1 .. All_Checks loop
Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
end loop;
end Initialize;
-------------------------
-- Insert_Range_Checks --
-------------------------
procedure Insert_Range_Checks
(Checks : Check_Result;
Node : Node_Id;
Suppress_Typ : Entity_Id;
Static_Sloc : Source_Ptr := No_Location;
Flag_Node : Node_Id := Empty;
Do_Before : Boolean := False)
is
Internal_Flag_Node : Node_Id := Flag_Node;
Internal_Static_Sloc : Source_Ptr := Static_Sloc;
Check_Node : Node_Id;
Checks_On : constant Boolean :=
(not Index_Checks_Suppressed (Suppress_Typ))
or else (not Range_Checks_Suppressed (Suppress_Typ));
begin
-- For now we just return if Checks_On is false, however this should be
-- enhanced to check for an always True value in the condition and to
-- generate a compilation warning???
if not Full_Expander_Active or else not Checks_On then
return;
end if;
if Static_Sloc = No_Location then
Internal_Static_Sloc := Sloc (Node);
end if;
if No (Flag_Node) then
Internal_Flag_Node := Node;
end if;
for J in 1 .. 2 loop
exit when No (Checks (J));
if Nkind (Checks (J)) = N_Raise_Constraint_Error
and then Present (Condition (Checks (J)))
then
if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
Check_Node := Checks (J);
Mark_Rewrite_Insertion (Check_Node);
if Do_Before then
Insert_Before_And_Analyze (Node, Check_Node);
else
Insert_After_And_Analyze (Node, Check_Node);
end if;
Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
end if;
else
Check_Node :=
Make_Raise_Constraint_Error (Internal_Static_Sloc,
Reason => CE_Range_Check_Failed);
Mark_Rewrite_Insertion (Check_Node);
if Do_Before then
Insert_Before_And_Analyze (Node, Check_Node);
else
Insert_After_And_Analyze (Node, Check_Node);
end if;
end if;
end loop;
end Insert_Range_Checks;
------------------------
-- Insert_Valid_Check --
------------------------
procedure Insert_Valid_Check (Expr : Node_Id) is
Loc : constant Source_Ptr := Sloc (Expr);
Exp : Node_Id;
begin
-- Do not insert if checks off, or if not checking validity or
-- if expression is known to be valid
if not Validity_Checks_On
or else Range_Or_Validity_Checks_Suppressed (Expr)
or else Expr_Known_Valid (Expr)
then
return;
end if;
-- If we have a checked conversion, then validity check applies to
-- the expression inside the conversion, not the result, since if
-- the expression inside is valid, then so is the conversion result.
Exp := Expr;
while Nkind (Exp) = N_Type_Conversion loop
Exp := Expression (Exp);
end loop;
-- We are about to insert the validity check for Exp. We save and
-- reset the Do_Range_Check flag over this validity check, and then
-- put it back for the final original reference (Exp may be rewritten).
declare
DRC : constant Boolean := Do_Range_Check (Exp);
PV : Node_Id;
CE : Node_Id;
begin
Set_Do_Range_Check (Exp, False);
-- Force evaluation to avoid multiple reads for atomic/volatile
if Is_Entity_Name (Exp)
and then Is_Volatile (Entity (Exp))
then
Force_Evaluation (Exp, Name_Req => True);
end if;
-- Build the prefix for the 'Valid call
PV := Duplicate_Subexpr_No_Checks (Exp, Name_Req => True);
-- A rather specialized kludge. If PV is an analyzed expression
-- which is an indexed component of a packed array that has not
-- been properly expanded, turn off its Analyzed flag to make sure
-- it gets properly reexpanded.
-- The reason this arises is that Duplicate_Subexpr_No_Checks did
-- an analyze with the old parent pointer. This may point e.g. to
-- a subprogram call, which deactivates this expansion.
if Analyzed (PV)
and then Nkind (PV) = N_Indexed_Component
and then Present (Packed_Array_Type (Etype (Prefix (PV))))
then
Set_Analyzed (PV, False);
end if;
-- Build the raise CE node to check for validity
CE :=
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Op_Not (Loc,
Right_Opnd =>
Make_Attribute_Reference (Loc,
Prefix => PV,
Attribute_Name => Name_Valid)),
Reason => CE_Invalid_Data);
-- Insert the validity check. Note that we do this with validity
-- checks turned off, to avoid recursion, we do not want validity
-- checks on the validity checking code itself!
Insert_Action (Expr, CE, Suppress => Validity_Check);
-- If the expression is a reference to an element of a bit-packed
-- array, then it is rewritten as a renaming declaration. If the
-- expression is an actual in a call, it has not been expanded,
-- waiting for the proper point at which to do it. The same happens
-- with renamings, so that we have to force the expansion now. This
-- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
-- and exp_ch6.adb.
if Is_Entity_Name (Exp)
and then Nkind (Parent (Entity (Exp))) =
N_Object_Renaming_Declaration
then
declare
Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
begin
if Nkind (Old_Exp) = N_Indexed_Component
and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
then
Expand_Packed_Element_Reference (Old_Exp);
end if;
end;
end if;
-- Put back the Do_Range_Check flag on the resulting (possibly
-- rewritten) expression.
-- Note: it might be thought that a validity check is not required
-- when a range check is present, but that's not the case, because
-- the back end is allowed to assume for the range check that the
-- operand is within its declared range (an assumption that validity
-- checking is all about NOT assuming!)
-- Note: no need to worry about Possible_Local_Raise here, it will
-- already have been called if original node has Do_Range_Check set.
Set_Do_Range_Check (Exp, DRC);
end;
end Insert_Valid_Check;
-------------------------------------
-- Is_Signed_Integer_Arithmetic_Op --
-------------------------------------
function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean is
begin
case Nkind (N) is
when N_Op_Abs | N_Op_Add | N_Op_Divide | N_Op_Expon |
N_Op_Minus | N_Op_Mod | N_Op_Multiply | N_Op_Plus |
N_Op_Rem | N_Op_Subtract =>
return Is_Signed_Integer_Type (Etype (N));
when N_If_Expression | N_Case_Expression =>
return Is_Signed_Integer_Type (Etype (N));
when others =>
return False;
end case;
end Is_Signed_Integer_Arithmetic_Op;
----------------------------------
-- Install_Null_Excluding_Check --
----------------------------------
procedure Install_Null_Excluding_Check (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (Parent (N));
Typ : constant Entity_Id := Etype (N);
function Safe_To_Capture_In_Parameter_Value return Boolean;
-- Determines if it is safe to capture Known_Non_Null status for an
-- the entity referenced by node N. The caller ensures that N is indeed
-- an entity name. It is safe to capture the non-null status for an IN
-- parameter when the reference occurs within a declaration that is sure
-- to be executed as part of the declarative region.
procedure Mark_Non_Null;
-- After installation of check, if the node in question is an entity
-- name, then mark this entity as non-null if possible.
function Safe_To_Capture_In_Parameter_Value return Boolean is
E : constant Entity_Id := Entity (N);
S : constant Entity_Id := Current_Scope;
S_Par : Node_Id;
begin
if Ekind (E) /= E_In_Parameter then
return False;
end if;
-- Two initial context checks. We must be inside a subprogram body
-- with declarations and reference must not appear in nested scopes.
if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
or else Scope (E) /= S
then
return False;
end if;
S_Par := Parent (Parent (S));
if Nkind (S_Par) /= N_Subprogram_Body
or else No (Declarations (S_Par))
then
return False;
end if;
declare
N_Decl : Node_Id;
P : Node_Id;
begin
-- Retrieve the declaration node of N (if any). Note that N
-- may be a part of a complex initialization expression.
P := Parent (N);
N_Decl := Empty;
while Present (P) loop
-- If we have a short circuit form, and we are within the right
-- hand expression, we return false, since the right hand side
-- is not guaranteed to be elaborated.
if Nkind (P) in N_Short_Circuit
and then N = Right_Opnd (P)
then
return False;
end if;
-- Similarly, if we are in an if expression and not part of the
-- condition, then we return False, since neither the THEN or
-- ELSE dependent expressions will always be elaborated.
if Nkind (P) = N_If_Expression
and then N /= First (Expressions (P))
then
return False;
end if;
-- If we are in a case expression, and not part of the
-- expression, then we return False, since a particular
-- dependent expression may not always be elaborated
if Nkind (P) = N_Case_Expression
and then N /= Expression (P)
then
return False;
end if;
-- While traversing the parent chain, we find that N
-- belongs to a statement, thus it may never appear in
-- a declarative region.
if Nkind (P) in N_Statement_Other_Than_Procedure_Call
or else Nkind (P) = N_Procedure_Call_Statement
then
return False;
end if;
-- If we are at a declaration, record it and exit
if Nkind (P) in N_Declaration
and then Nkind (P) not in N_Subprogram_Specification
then
N_Decl := P;
exit;
end if;
P := Parent (P);
end loop;
if No (N_Decl) then
return False;
end if;
return List_Containing (N_Decl) = Declarations (S_Par);
end;
end Safe_To_Capture_In_Parameter_Value;
-------------------
-- Mark_Non_Null --
-------------------
procedure Mark_Non_Null is
begin
-- Only case of interest is if node N is an entity name
if Is_Entity_Name (N) then
-- For sure, we want to clear an indication that this is known to
-- be null, since if we get past this check, it definitely is not!
Set_Is_Known_Null (Entity (N), False);
-- We can mark the entity as known to be non-null if either it is
-- safe to capture the value, or in the case of an IN parameter,
-- which is a constant, if the check we just installed is in the
-- declarative region of the subprogram body. In this latter case,
-- a check is decisive for the rest of the body if the expression
-- is sure to be elaborated, since we know we have to elaborate
-- all declarations before executing the body.
-- Couldn't this always be part of Safe_To_Capture_Value ???
if Safe_To_Capture_Value (N, Entity (N))
or else Safe_To_Capture_In_Parameter_Value
then
Set_Is_Known_Non_Null (Entity (N));
end if;
end if;
end Mark_Non_Null;
-- Start of processing for Install_Null_Excluding_Check
begin
pragma Assert (Is_Access_Type (Typ));
-- No check inside a generic (why not???)
if Inside_A_Generic then
return;
end if;
-- No check needed if known to be non-null
if Known_Non_Null (N) then
return;
end if;
-- If known to be null, here is where we generate a compile time check
if Known_Null (N) then
-- Avoid generating warning message inside init procs
if not Inside_Init_Proc then
Apply_Compile_Time_Constraint_Error
(N,
"null value not allowed here??",
CE_Access_Check_Failed);
else
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Reason => CE_Access_Check_Failed));
end if;
Mark_Non_Null;
return;
end if;
-- If entity is never assigned, for sure a warning is appropriate
if Is_Entity_Name (N) then
Check_Unset_Reference (N);
end if;
-- No check needed if checks are suppressed on the range. Note that we
-- don't set Is_Known_Non_Null in this case (we could legitimately do
-- so, since the program is erroneous, but we don't like to casually
-- propagate such conclusions from erroneosity).
if Access_Checks_Suppressed (Typ) then
return;
end if;
-- No check needed for access to concurrent record types generated by
-- the expander. This is not just an optimization (though it does indeed
-- remove junk checks). It also avoids generation of junk warnings.
if Nkind (N) in N_Has_Chars
and then Chars (N) = Name_uObject
and then Is_Concurrent_Record_Type
(Directly_Designated_Type (Etype (N)))
then
return;
end if;
-- No check needed for the Get_Current_Excep.all.all idiom generated by
-- the expander within exception handlers, since we know that the value
-- can never be null.
-- Is this really the right way to do this? Normally we generate such
-- code in the expander with checks off, and that's how we suppress this
-- kind of junk check ???
if Nkind (N) = N_Function_Call
and then Nkind (Name (N)) = N_Explicit_Dereference
and then Nkind (Prefix (Name (N))) = N_Identifier
and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep)
then
return;
end if;
-- Otherwise install access check
Insert_Action (N,
Make_Raise_Constraint_Error (Loc,
Condition =>
Make_Op_Eq (Loc,
Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
Right_Opnd => Make_Null (Loc)),
Reason => CE_Access_Check_Failed));
Mark_Non_Null;
end Install_Null_Excluding_Check;
--------------------------
-- Install_Static_Check --
--------------------------
procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
Stat : constant Boolean := Is_Static_Expression (R_Cno);
Typ : constant Entity_Id := Etype (R_Cno);
begin
Rewrite (R_Cno,
Make_Raise_Constraint_Error (Loc,
Reason => CE_Range_Check_Failed));
Set_Analyzed (R_Cno);
Set_Etype (R_Cno, Typ);
Set_Raises_Constraint_Error (R_Cno);
Set_Is_Static_Expression (R_Cno, Stat);
-- Now deal with possible local raise handling
Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
end Install_Static_Check;
-------------------------
-- Is_Check_Suppressed --
-------------------------
function Is_Check_Suppressed (E : Entity_Id; C : Check_Id) return Boolean is
Ptr : Suppress_Stack_Entry_Ptr;
begin
-- First search the local entity suppress stack. We search this from the
-- top of the stack down so that we get the innermost entry that applies
-- to this case if there are nested entries.
Ptr := Local_Suppress_Stack_Top;
while Ptr /= null loop
if (Ptr.Entity = Empty or else Ptr.Entity = E)
and then (Ptr.Check = All_Checks or else Ptr.Check = C)
then
return Ptr.Suppress;
end if;
Ptr := Ptr.Prev;
end loop;
-- Now search the global entity suppress table for a matching entry.
-- We also search this from the top down so that if there are multiple
-- pragmas for the same entity, the last one applies (not clear what
-- or whether the RM specifies this handling, but it seems reasonable).
Ptr := Global_Suppress_Stack_Top;
while Ptr /= null loop
if (Ptr.Entity = Empty or else Ptr.Entity = E)
and then (Ptr.Check = All_Checks or else Ptr.Check = C)
then
return Ptr.Suppress;
end if;
Ptr := Ptr.Prev;
end loop;
-- If we did not find a matching entry, then use the normal scope
-- suppress value after all (actually this will be the global setting
-- since it clearly was not overridden at any point). For a predefined
-- check, we test the specific flag. For a user defined check, we check
-- the All_Checks flag. The Overflow flag requires special handling to
-- deal with the General vs Assertion case
if C = Overflow_Check then
return Overflow_Checks_Suppressed (Empty);
elsif C in Predefined_Check_Id then
return Scope_Suppress.Suppress (C);
else
return Scope_Suppress.Suppress (All_Checks);
end if;
end Is_Check_Suppressed;
---------------------
-- Kill_All_Checks --
---------------------
procedure Kill_All_Checks is
begin
if Debug_Flag_CC then
w ("Kill_All_Checks");
end if;
-- We reset the number of saved checks to zero, and also modify all
-- stack entries for statement ranges to indicate that the number of
-- checks at each level is now zero.
Num_Saved_Checks := 0;
-- Note: the Int'Min here avoids any possibility of J being out of
-- range when called from e.g. Conditional_Statements_Begin.
for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
Saved_Checks_Stack (J) := 0;
end loop;
end Kill_All_Checks;
-----------------
-- Kill_Checks --
-----------------
procedure Kill_Checks (V : Entity_Id) is
begin
if Debug_Flag_CC then
w ("Kill_Checks for entity", Int (V));
end if;
for J in 1 .. Num_Saved_Checks loop
if Saved_Checks (J).Entity = V then
if Debug_Flag_CC then
w (" Checks killed for saved check ", J);
end if;
Saved_Checks (J).Killed := True;
end if;
end loop;
end Kill_Checks;
------------------------------
-- Length_Checks_Suppressed --
------------------------------
function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Length_Check);
else
return Scope_Suppress.Suppress (Length_Check);
end if;
end Length_Checks_Suppressed;
-----------------------
-- Make_Bignum_Block --
-----------------------
function Make_Bignum_Block (Loc : Source_Ptr) return Node_Id is
M : constant Entity_Id := Make_Defining_Identifier (Loc, Name_uM);
begin
return
Make_Block_Statement (Loc,
Declarations => New_List (
Make_Object_Declaration (Loc,
Defining_Identifier => M,
Object_Definition =>
New_Occurrence_Of (RTE (RE_Mark_Id), Loc),
Expression =>
Make_Function_Call (Loc,
Name => New_Reference_To (RTE (RE_SS_Mark), Loc)))),
Handled_Statement_Sequence =>
Make_Handled_Sequence_Of_Statements (Loc,
Statements => New_List (
Make_Procedure_Call_Statement (Loc,
Name => New_Occurrence_Of (RTE (RE_SS_Release), Loc),
Parameter_Associations => New_List (
New_Reference_To (M, Loc))))));
end Make_Bignum_Block;
----------------------------------
-- Minimize_Eliminate_Overflows --
----------------------------------
-- This is a recursive routine that is called at the top of an expression
-- tree to properly process overflow checking for a whole subtree by making
-- recursive calls to process operands. This processing may involve the use
-- of bignum or long long integer arithmetic, which will change the types
-- of operands and results. That's why we can't do this bottom up (since
-- it would interfere with semantic analysis).
-- What happens is that if MINIMIZED/ELIMINATED mode is in effect then
-- the operator expansion routines, as well as the expansion routines for
-- if/case expression, do nothing (for the moment) except call the routine
-- to apply the overflow check (Apply_Arithmetic_Overflow_Check). That
-- routine does nothing for non top-level nodes, so at the point where the
-- call is made for the top level node, the entire expression subtree has
-- not been expanded, or processed for overflow. All that has to happen as
-- a result of the top level call to this routine.
-- As noted above, the overflow processing works by making recursive calls
-- for the operands, and figuring out what to do, based on the processing
-- of these operands (e.g. if a bignum operand appears, the parent op has
-- to be done in bignum mode), and the determined ranges of the operands.
-- After possible rewriting of a constituent subexpression node, a call is
-- made to either reexpand the node (if nothing has changed) or reanalyze
-- the node (if it has been modified by the overflow check processing). The
-- Analyzed_Flag is set to False before the reexpand/reanalyze. To avoid
-- a recursive call into the whole overflow apparatus, an important rule
-- for this call is that the overflow handling mode must be temporarily set
-- to STRICT.
procedure Minimize_Eliminate_Overflows
(N : Node_Id;
Lo : out Uint;
Hi : out Uint;
Top_Level : Boolean)
is
Rtyp : constant Entity_Id := Etype (N);
pragma Assert (Is_Signed_Integer_Type (Rtyp));
-- Result type, must be a signed integer type
Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
pragma Assert (Check_Mode in Minimized_Or_Eliminated);
Loc : constant Source_Ptr := Sloc (N);
Rlo, Rhi : Uint;
-- Ranges of values for right operand (operator case)
Llo, Lhi : Uint;
-- Ranges of values for left operand (operator case)
LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
-- Operands and results are of this type when we convert
LLLo : constant Uint := Intval (Type_Low_Bound (LLIB));
LLHi : constant Uint := Intval (Type_High_Bound (LLIB));
-- Bounds of Long_Long_Integer
Binary : constant Boolean := Nkind (N) in N_Binary_Op;
-- Indicates binary operator case
OK : Boolean;
-- Used in call to Determine_Range
Bignum_Operands : Boolean;
-- Set True if one or more operands is already of type Bignum, meaning
-- that for sure (regardless of Top_Level setting) we are committed to
-- doing the operation in Bignum mode (or in the case of a case or if
-- expression, converting all the dependent expressions to Bignum).
Long_Long_Integer_Operands : Boolean;
-- Set True if one or more operands is already of type Long_Long_Integer
-- which means that if the result is known to be in the result type
-- range, then we must convert such operands back to the result type.
procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False);
-- This is called when we have modified the node and we therefore need
-- to reanalyze it. It is important that we reset the mode to STRICT for
-- this reanalysis, since if we leave it in MINIMIZED or ELIMINATED mode
-- we would reenter this routine recursively which would not be good!
-- The argument Suppress is set True if we also want to suppress
-- overflow checking for the reexpansion (this is set when we know
-- overflow is not possible). Typ is the type for the reanalysis.
procedure Reexpand (Suppress : Boolean := False);
-- This is like Reanalyze, but does not do the Analyze step, it only
-- does a reexpansion. We do this reexpansion in STRICT mode, so that
-- instead of reentering the MINIMIZED/ELIMINATED mode processing, we
-- follow the normal expansion path (e.g. converting A**4 to A**2**2).
-- Note that skipping reanalysis is not just an optimization, testing
-- has showed up several complex cases in which reanalyzing an already
-- analyzed node causes incorrect behavior.
function In_Result_Range return Boolean;
-- Returns True iff Lo .. Hi are within range of the result type
procedure Max (A : in out Uint; B : Uint);
-- If A is No_Uint, sets A to B, else to UI_Max (A, B)
procedure Min (A : in out Uint; B : Uint);
-- If A is No_Uint, sets A to B, else to UI_Min (A, B)
---------------------
-- In_Result_Range --
---------------------
function In_Result_Range return Boolean is
begin
if Lo = No_Uint or else Hi = No_Uint then
return False;
elsif Is_Static_Subtype (Etype (N)) then
return Lo >= Expr_Value (Type_Low_Bound (Rtyp))
and then
Hi <= Expr_Value (Type_High_Bound (Rtyp));
else
return Lo >= Expr_Value (Type_Low_Bound (Base_Type (Rtyp)))
and then
Hi <= Expr_Value (Type_High_Bound (Base_Type (Rtyp)));
end if;
end In_Result_Range;
---------
-- Max --
---------
procedure Max (A : in out Uint; B : Uint) is
begin
if A = No_Uint or else B > A then
A := B;
end if;
end Max;
---------
-- Min --
---------
procedure Min (A : in out Uint; B : Uint) is
begin
if A = No_Uint or else B < A then
A := B;
end if;
end Min;
---------------
-- Reanalyze --
---------------
procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False) is
Svg : constant Overflow_Mode_Type :=
Scope_Suppress.Overflow_Mode_General;
Sva : constant Overflow_Mode_Type :=
Scope_Suppress.Overflow_Mode_Assertions;
Svo : constant Boolean :=
Scope_Suppress.Suppress (Overflow_Check);
begin
Scope_Suppress.Overflow_Mode_General := Strict;
Scope_Suppress.Overflow_Mode_Assertions := Strict;
if Suppress then
Scope_Suppress.Suppress (Overflow_Check) := True;
end if;
Analyze_And_Resolve (N, Typ);
Scope_Suppress.Suppress (Overflow_Check) := Svo;
Scope_Suppress.Overflow_Mode_General := Svg;
Scope_Suppress.Overflow_Mode_Assertions := Sva;
end Reanalyze;
--------------
-- Reexpand --
--------------
procedure Reexpand (Suppress : Boolean := False) is
Svg : constant Overflow_Mode_Type :=
Scope_Suppress.Overflow_Mode_General;
Sva : constant Overflow_Mode_Type :=
Scope_Suppress.Overflow_Mode_Assertions;
Svo : constant Boolean :=
Scope_Suppress.Suppress (Overflow_Check);
begin
Scope_Suppress.Overflow_Mode_General := Strict;
Scope_Suppress.Overflow_Mode_Assertions := Strict;
Set_Analyzed (N, False);
if Suppress then
Scope_Suppress.Suppress (Overflow_Check) := True;
end if;
Expand (N);
Scope_Suppress.Suppress (Overflow_Check) := Svo;
Scope_Suppress.Overflow_Mode_General := Svg;
Scope_Suppress.Overflow_Mode_Assertions := Sva;
end Reexpand;
-- Start of processing for Minimize_Eliminate_Overflows
begin
-- Case where we do not have a signed integer arithmetic operation
if not Is_Signed_Integer_Arithmetic_Op (N) then
-- Use the normal Determine_Range routine to get the range. We
-- don't require operands to be valid, invalid values may result in
-- rubbish results where the result has not been properly checked for
-- overflow, that's fine!
Determine_Range (N, OK, Lo, Hi, Assume_Valid => False);
-- If Determine_Range did not work (can this in fact happen? Not
-- clear but might as well protect), use type bounds.
if not OK then
Lo := Intval (Type_Low_Bound (Base_Type (Etype (N))));
Hi := Intval (Type_High_Bound (Base_Type (Etype (N))));
end if;
-- If we don't have a binary operator, all we have to do is to set
-- the Hi/Lo range, so we are done
return;
-- Processing for if expression
elsif Nkind (N) = N_If_Expression then
declare
Then_DE : constant Node_Id := Next (First (Expressions (N)));
Else_DE : constant Node_Id := Next (Then_DE);
begin
Bignum_Operands := False;
Minimize_Eliminate_Overflows
(Then_DE, Lo, Hi, Top_Level => False);
if Lo = No_Uint then
Bignum_Operands := True;
end if;
Minimize_Eliminate_Overflows
(Else_DE, Rlo, Rhi, Top_Level => False);
if Rlo = No_Uint then
Bignum_Operands := True;
else
Long_Long_Integer_Operands :=
Etype (Then_DE) = LLIB or else Etype (Else_DE) = LLIB;
Min (Lo, Rlo);
Max (Hi, Rhi);
end if;
-- If at least one of our operands is now Bignum, we must rebuild
-- the if expression to use Bignum operands. We will analyze the
-- rebuilt if expression with overflow checks off, since once we
-- are in bignum mode, we are all done with overflow checks!
if Bignum_Operands then
Rewrite (N,
Make_If_Expression (Loc,
Expressions => New_List (
Remove_Head (Expressions (N)),
Convert_To_Bignum (Then_DE),
Convert_To_Bignum (Else_DE)),
Is_Elsif => Is_Elsif (N)));
Reanalyze (RTE (RE_Bignum), Suppress => True);
-- If we have no Long_Long_Integer operands, then we are in result
-- range, since it means that none of our operands felt the need
-- to worry about overflow (otherwise it would have already been
-- converted to long long integer or bignum). We reexpand to
-- complete the expansion of the if expression (but we do not
-- need to reanalyze).
elsif not Long_Long_Integer_Operands then
Set_Do_Overflow_Check (N, False);
Reexpand;
-- Otherwise convert us to long long integer mode. Note that we
-- don't need any further overflow checking at this level.
else
Convert_To_And_Rewrite (LLIB, Then_DE);
Convert_To_And_Rewrite (LLIB, Else_DE);
Set_Etype (N, LLIB);
-- Now reanalyze with overflow checks off
Set_Do_Overflow_Check (N, False);
Reanalyze (LLIB, Suppress => True);
end if;
end;
return;
-- Here for case expression
elsif Nkind (N) = N_Case_Expression then
Bignum_Operands := False;
Long_Long_Integer_Operands := False;
declare
Alt : Node_Id;
begin
-- Loop through expressions applying recursive call
Alt := First (Alternatives (N));
while Present (Alt) loop
declare
Aexp : constant Node_Id := Expression (Alt);
begin
Minimize_Eliminate_Overflows
(Aexp, Lo, Hi, Top_Level => False);
if Lo = No_Uint then
Bignum_Operands := True;
elsif Etype (Aexp) = LLIB then
Long_Long_Integer_Operands := True;
end if;
end;
Next (Alt);
end loop;
-- If we have no bignum or long long integer operands, it means
-- that none of our dependent expressions could raise overflow.
-- In this case, we simply return with no changes except for
-- resetting the overflow flag, since we are done with overflow
-- checks for this node. We will reexpand to get the needed
-- expansion for the case expression, but we do not need to
-- reanalyze, since nothing has changed.
if not (Bignum_Operands or Long_Long_Integer_Operands) then
Set_Do_Overflow_Check (N, False);
Reexpand (Suppress => True);
-- Otherwise we are going to rebuild the case expression using
-- either bignum or long long integer operands throughout.
else
declare
Rtype : Entity_Id;
New_Alts : List_Id;
New_Exp : Node_Id;
begin
New_Alts := New_List;
Alt := First (Alternatives (N));
while Present (Alt) loop
if Bignum_Operands then
New_Exp := Convert_To_Bignum (Expression (Alt));
Rtype := RTE (RE_Bignum);
else
New_Exp := Convert_To (LLIB, Expression (Alt));
Rtype := LLIB;
end if;
Append_To (New_Alts,
Make_Case_Expression_Alternative (Sloc (Alt),
Actions => No_List,
Discrete_Choices => Discrete_Choices (Alt),
Expression => New_Exp));
Next (Alt);
end loop;
Rewrite (N,
Make_Case_Expression (Loc,
Expression => Expression (N),
Alternatives => New_Alts));
Reanalyze (Rtype, Suppress => True);
end;
end if;
end;
return;
end if;
-- If we have an arithmetic operator we make recursive calls on the
-- operands to get the ranges (and to properly process the subtree
-- that lies below us!)
Minimize_Eliminate_Overflows
(Right_Opnd (N), Rlo, Rhi, Top_Level => False);
if Binary then
Minimize_Eliminate_Overflows
(Left_Opnd (N), Llo, Lhi, Top_Level => False);
end if;
-- Record if we have Long_Long_Integer operands
Long_Long_Integer_Operands :=
Etype (Right_Opnd (N)) = LLIB
or else (Binary and then Etype (Left_Opnd (N)) = LLIB);
-- If either operand is a bignum, then result will be a bignum and we
-- don't need to do any range analysis. As previously discussed we could
-- do range analysis in such cases, but it could mean working with giant
-- numbers at compile time for very little gain (the number of cases
-- in which we could slip back from bignum mode is small).
if Rlo = No_Uint or else (Binary and then Llo = No_Uint) then
Lo := No_Uint;
Hi := No_Uint;
Bignum_Operands := True;
-- Otherwise compute result range
else
Bignum_Operands := False;
case Nkind (N) is
-- Absolute value
when N_Op_Abs =>
Lo := Uint_0;
Hi := UI_Max (abs Rlo, abs Rhi);
-- Addition
when N_Op_Add =>
Lo := Llo + Rlo;
Hi := Lhi + Rhi;
-- Division
when N_Op_Divide =>
-- If the right operand can only be zero, set 0..0
if Rlo = 0 and then Rhi = 0 then
Lo := Uint_0;
Hi := Uint_0;
-- Possible bounds of division must come from dividing end
-- values of the input ranges (four possibilities), provided
-- zero is not included in the possible values of the right
-- operand.
-- Otherwise, we just consider two intervals of values for
-- the right operand: the interval of negative values (up to
-- -1) and the interval of positive values (starting at 1).
-- Since division by 1 is the identity, and division by -1
-- is negation, we get all possible bounds of division in that
-- case by considering:
-- - all values from the division of end values of input
-- ranges;
-- - the end values of the left operand;
-- - the negation of the end values of the left operand.
else
declare
Mrk : constant Uintp.Save_Mark := Mark;
-- Mark so we can release the RR and Ev values
Ev1 : Uint;
Ev2 : Uint;
Ev3 : Uint;
Ev4 : Uint;
begin
-- Discard extreme values of zero for the divisor, since
-- they will simply result in an exception in any case.
if Rlo = 0 then
Rlo := Uint_1;
elsif Rhi = 0 then
Rhi := -Uint_1;
end if;
-- Compute possible bounds coming from dividing end
-- values of the input ranges.
Ev1 := Llo / Rlo;
Ev2 := Llo / Rhi;
Ev3 := Lhi / Rlo;
Ev4 := Lhi / Rhi;
Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
-- If the right operand can be both negative or positive,
-- include the end values of the left operand in the
-- extreme values, as well as their negation.
if Rlo < 0 and then Rhi > 0 then
Ev1 := Llo;
Ev2 := -Llo;
Ev3 := Lhi;
Ev4 := -Lhi;
Min (Lo,
UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4)));
Max (Hi,
UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4)));
end if;
-- Release the RR and Ev values
Release_And_Save (Mrk, Lo, Hi);
end;
end if;
-- Exponentiation
when N_Op_Expon =>
-- Discard negative values for the exponent, since they will
-- simply result in an exception in any case.
if Rhi < 0 then
Rhi := Uint_0;
elsif Rlo < 0 then
Rlo := Uint_0;
end if;
-- Estimate number of bits in result before we go computing
-- giant useless bounds. Basically the number of bits in the
-- result is the number of bits in the base multiplied by the
-- value of the exponent. If this is big enough that the result
-- definitely won't fit in Long_Long_Integer, switch to bignum
-- mode immediately, and avoid computing giant bounds.
-- The comparison here is approximate, but conservative, it
-- only clicks on cases that are sure to exceed the bounds.
if Num_Bits (UI_Max (abs Llo, abs Lhi)) * Rhi + 1 > 100 then
Lo := No_Uint;
Hi := No_Uint;
-- If right operand is zero then result is 1
elsif Rhi = 0 then
Lo := Uint_1;
Hi := Uint_1;
else
-- High bound comes either from exponentiation of largest
-- positive value to largest exponent value, or from
-- the exponentiation of most negative value to an
-- even exponent.
declare
Hi1, Hi2 : Uint;
begin
if Lhi > 0 then
Hi1 := Lhi ** Rhi;
else
Hi1 := Uint_0;
end if;
if Llo < 0 then
if Rhi mod 2 = 0 then
Hi2 := Llo ** Rhi;
else
Hi2 := Llo ** (Rhi - 1);
end if;
else
Hi2 := Uint_0;
end if;
Hi := UI_Max (Hi1, Hi2);
end;
-- Result can only be negative if base can be negative
if Llo < 0 then
if Rhi mod 2 = 0 then
Lo := Llo ** (Rhi - 1);
else
Lo := Llo ** Rhi;
end if;
-- Otherwise low bound is minimum ** minimum
else
Lo := Llo ** Rlo;
end if;
end if;
-- Negation
when N_Op_Minus =>
Lo := -Rhi;
Hi := -Rlo;
-- Mod
when N_Op_Mod =>
declare
Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
-- This is the maximum absolute value of the result
begin
Lo := Uint_0;
Hi := Uint_0;
-- The result depends only on the sign and magnitude of
-- the right operand, it does not depend on the sign or
-- magnitude of the left operand.
if Rlo < 0 then
Lo := -Maxabs;
end if;
if Rhi > 0 then
Hi := Maxabs;
end if;
end;
-- Multiplication
when N_Op_Multiply =>
-- Possible bounds of multiplication must come from multiplying
-- end values of the input ranges (four possibilities).
declare
Mrk : constant Uintp.Save_Mark := Mark;
-- Mark so we can release the Ev values
Ev1 : constant Uint := Llo * Rlo;
Ev2 : constant Uint := Llo * Rhi;
Ev3 : constant Uint := Lhi * Rlo;
Ev4 : constant Uint := Lhi * Rhi;
begin
Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
-- Release the Ev values
Release_And_Save (Mrk, Lo, Hi);
end;
-- Plus operator (affirmation)
when N_Op_Plus =>
Lo := Rlo;
Hi := Rhi;
-- Remainder
when N_Op_Rem =>
declare
Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
-- This is the maximum absolute value of the result. Note
-- that the result range does not depend on the sign of the
-- right operand.
begin
Lo := Uint_0;
Hi := Uint_0;
-- Case of left operand negative, which results in a range
-- of -Maxabs .. 0 for those negative values. If there are
-- no negative values then Lo value of result is always 0.
if Llo < 0 then
Lo := -Maxabs;
end if;
-- Case of left operand positive
if Lhi > 0 then
Hi := Maxabs;
end if;
end;
-- Subtract
when N_Op_Subtract =>
Lo := Llo - Rhi;
Hi := Lhi - Rlo;
-- Nothing else should be possible
when others =>
raise Program_Error;
end case;
end if;
-- Here for the case where we have not rewritten anything (no bignum
-- operands or long long integer operands), and we know the result.
-- If we know we are in the result range, and we do not have Bignum
-- operands or Long_Long_Integer operands, we can just reexpand with
-- overflow checks turned off (since we know we cannot have overflow).
-- As always the reexpansion is required to complete expansion of the
-- operator, but we do not need to reanalyze, and we prevent recursion
-- by suppressing the check.
if not (Bignum_Operands or Long_Long_Integer_Operands)
and then In_Result_Range
then
Set_Do_Overflow_Check (N, False);
Reexpand (Suppress => True);
return;
-- Here we know that we are not in the result range, and in the general
-- case we will move into either the Bignum or Long_Long_Integer domain
-- to compute the result. However, there is one exception. If we are
-- at the top level, and we do not have Bignum or Long_Long_Integer
-- operands, we will have to immediately convert the result back to
-- the result type, so there is no point in Bignum/Long_Long_Integer
-- fiddling.
elsif Top_Level
and then not (Bignum_Operands or Long_Long_Integer_Operands)
-- One further refinement. If we are at the top level, but our parent
-- is a type conversion, then go into bignum or long long integer node
-- since the result will be converted to that type directly without
-- going through the result type, and we may avoid an overflow. This
-- is the case for example of Long_Long_Integer (A ** 4), where A is
-- of type Integer, and the result A ** 4 fits in Long_Long_Integer
-- but does not fit in Integer.
and then Nkind (Parent (N)) /= N_Type_Conversion
then
-- Here keep original types, but we need to complete analysis
-- One subtlety. We can't just go ahead and do an analyze operation
-- here because it will cause recursion into the whole MINIMIZED/
-- ELIMINATED overflow processing which is not what we want. Here
-- we are at the top level, and we need a check against the result
-- mode (i.e. we want to use STRICT mode). So do exactly that!
-- Also, we have not modified the node, so this is a case where
-- we need to reexpand, but not reanalyze.
Reexpand;
return;
-- Cases where we do the operation in Bignum mode. This happens either
-- because one of our operands is in Bignum mode already, or because
-- the computed bounds are outside the bounds of Long_Long_Integer,
-- which in some cases can be indicated by Hi and Lo being No_Uint.
-- Note: we could do better here and in some cases switch back from
-- Bignum mode to normal mode, e.g. big mod 2 must be in the range
-- 0 .. 1, but the cases are rare and it is not worth the effort.
-- Failing to do this switching back is only an efficiency issue.
elsif Lo = No_Uint or else Lo < LLLo or else Hi > LLHi then
-- OK, we are definitely outside the range of Long_Long_Integer. The
-- question is whether to move to Bignum mode, or stay in the domain
-- of Long_Long_Integer, signalling that an overflow check is needed.
-- Obviously in MINIMIZED mode we stay with LLI, since we are not in
-- the Bignum business. In ELIMINATED mode, we will normally move
-- into Bignum mode, but there is an exception if neither of our
-- operands is Bignum now, and we are at the top level (Top_Level
-- set True). In this case, there is no point in moving into Bignum
-- mode to prevent overflow if the caller will immediately convert
-- the Bignum value back to LLI with an overflow check. It's more
-- efficient to stay in LLI mode with an overflow check (if needed)
if Check_Mode = Minimized
or else (Top_Level and not Bignum_Operands)
then
if Do_Overflow_Check (N) then
Enable_Overflow_Check (N);
end if;
-- The result now has to be in Long_Long_Integer mode, so adjust
-- the possible range to reflect this. Note these calls also
-- change No_Uint values from the top level case to LLI bounds.
Max (Lo, LLLo);
Min (Hi, LLHi);
-- Otherwise we are in ELIMINATED mode and we switch to Bignum mode
else
pragma Assert (Check_Mode = Eliminated);
declare
Fent : Entity_Id;
Args : List_Id;
begin
case Nkind (N) is
when N_Op_Abs =>
Fent := RTE (RE_Big_Abs);
when N_Op_Add =>
Fent := RTE (RE_Big_Add);
when N_Op_Divide =>
Fent := RTE (RE_Big_Div);
when N_Op_Expon =>
Fent := RTE (RE_Big_Exp);
when N_Op_Minus =>
Fent := RTE (RE_Big_Neg);
when N_Op_Mod =>
Fent := RTE (RE_Big_Mod);
when N_Op_Multiply =>
Fent := RTE (RE_Big_Mul);
when N_Op_Rem =>
Fent := RTE (RE_Big_Rem);
when N_Op_Subtract =>
Fent := RTE (RE_Big_Sub);
-- Anything else is an internal error, this includes the
-- N_Op_Plus case, since how can plus cause the result
-- to be out of range if the operand is in range?
when others =>
raise Program_Error;
end case;
-- Construct argument list for Bignum call, converting our
-- operands to Bignum form if they are not already there.
Args := New_List;
if Binary then
Append_To (Args, Convert_To_Bignum (Left_Opnd (N)));
end if;
Append_To (Args, Convert_To_Bignum (Right_Opnd (N)));
-- Now rewrite the arithmetic operator with a call to the
-- corresponding bignum function.
Rewrite (N,
Make_Function_Call (Loc,
Name => New_Occurrence_Of (Fent, Loc),
Parameter_Associations => Args));
Reanalyze (RTE (RE_Bignum), Suppress => True);
-- Indicate result is Bignum mode
Lo := No_Uint;
Hi := No_Uint;
return;
end;
end if;
-- Otherwise we are in range of Long_Long_Integer, so no overflow
-- check is required, at least not yet.
else
Set_Do_Overflow_Check (N, False);
end if;
-- Here we are not in Bignum territory, but we may have long long
-- integer operands that need special handling. First a special check:
-- If an exponentiation operator exponent is of type Long_Long_Integer,
-- it means we converted it to prevent overflow, but exponentiation
-- requires a Natural right operand, so convert it back to Natural.
-- This conversion may raise an exception which is fine.
if Nkind (N) = N_Op_Expon and then Etype (Right_Opnd (N)) = LLIB then
Convert_To_And_Rewrite (Standard_Natural, Right_Opnd (N));
end if;
-- Here we will do the operation in Long_Long_Integer. We do this even
-- if we know an overflow check is required, better to do this in long
-- long integer mode, since we are less likely to overflow!
-- Convert right or only operand to Long_Long_Integer, except that
-- we do not touch the exponentiation right operand.
if Nkind (N) /= N_Op_Expon then
Convert_To_And_Rewrite (LLIB, Right_Opnd (N));
end if;
-- Convert left operand to Long_Long_Integer for binary case
if Binary then
Convert_To_And_Rewrite (LLIB, Left_Opnd (N));
end if;
-- Reset node to unanalyzed
Set_Analyzed (N, False);
Set_Etype (N, Empty);
Set_Entity (N, Empty);
-- Now analyze this new node. This reanalysis will complete processing
-- for the node. In particular we will complete the expansion of an
-- exponentiation operator (e.g. changing A ** 2 to A * A), and also
-- we will complete any division checks (since we have not changed the
-- setting of the Do_Division_Check flag).
-- We do this reanalysis in STRICT mode to avoid recursion into the
-- MINIMIZED/ELIMINATED handling, since we are now done with that!
declare
SG : constant Overflow_Mode_Type :=
Scope_Suppress.Overflow_Mode_General;
SA : constant Overflow_Mode_Type :=
Scope_Suppress.Overflow_Mode_Assertions;
begin
Scope_Suppress.Overflow_Mode_General := Strict;
Scope_Suppress.Overflow_Mode_Assertions := Strict;
if not Do_Overflow_Check (N) then
Reanalyze (LLIB, Suppress => True);
else
Reanalyze (LLIB);
end if;
Scope_Suppress.Overflow_Mode_General := SG;
Scope_Suppress.Overflow_Mode_Assertions := SA;
end;
end Minimize_Eliminate_Overflows;
-------------------------
-- Overflow_Check_Mode --
-------------------------
function Overflow_Check_Mode return Overflow_Mode_Type is
begin
if In_Assertion_Expr = 0 then
return Scope_Suppress.Overflow_Mode_General;
else
return Scope_Suppress.Overflow_Mode_Assertions;
end if;
end Overflow_Check_Mode;
--------------------------------
-- Overflow_Checks_Suppressed --
--------------------------------
function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Overflow_Check);
else
return Scope_Suppress.Suppress (Overflow_Check);
end if;
end Overflow_Checks_Suppressed;
-----------------------------
-- Range_Checks_Suppressed --
-----------------------------
function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) then
-- Note: for now we always suppress range checks on Vax float types,
-- since Gigi does not know how to generate these checks.
if Vax_Float (E) then
return True;
elsif Kill_Range_Checks (E) then
return True;
elsif Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Range_Check);
end if;
end if;
return Scope_Suppress.Suppress (Range_Check);
end Range_Checks_Suppressed;
-----------------------------------------
-- Range_Or_Validity_Checks_Suppressed --
-----------------------------------------
-- Note: the coding would be simpler here if we simply made appropriate
-- calls to Range/Validity_Checks_Suppressed, but that would result in
-- duplicated checks which we prefer to avoid.
function Range_Or_Validity_Checks_Suppressed
(Expr : Node_Id) return Boolean
is
begin
-- Immediate return if scope checks suppressed for either check
if Scope_Suppress.Suppress (Range_Check)
or
Scope_Suppress.Suppress (Validity_Check)
then
return True;
end if;
-- If no expression, that's odd, decide that checks are suppressed,
-- since we don't want anyone trying to do checks in this case, which
-- is most likely the result of some other error.
if No (Expr) then
return True;
end if;
-- Expression is present, so perform suppress checks on type
declare
Typ : constant Entity_Id := Etype (Expr);
begin
if Vax_Float (Typ) then
return True;
elsif Checks_May_Be_Suppressed (Typ)
and then (Is_Check_Suppressed (Typ, Range_Check)
or else
Is_Check_Suppressed (Typ, Validity_Check))
then
return True;
end if;
end;
-- If expression is an entity name, perform checks on this entity
if Is_Entity_Name (Expr) then
declare
Ent : constant Entity_Id := Entity (Expr);
begin
if Checks_May_Be_Suppressed (Ent) then
return Is_Check_Suppressed (Ent, Range_Check)
or else Is_Check_Suppressed (Ent, Validity_Check);
end if;
end;
end if;
-- If we fall through, no checks suppressed
return False;
end Range_Or_Validity_Checks_Suppressed;
-------------------
-- Remove_Checks --
-------------------
procedure Remove_Checks (Expr : Node_Id) is
function Process (N : Node_Id) return Traverse_Result;
-- Process a single node during the traversal
procedure Traverse is new Traverse_Proc (Process);
-- The traversal procedure itself
-------------
-- Process --
-------------
function Process (N : Node_Id) return Traverse_Result is
begin
if Nkind (N) not in N_Subexpr then
return Skip;
end if;
Set_Do_Range_Check (N, False);
case Nkind (N) is
when N_And_Then =>
Traverse (Left_Opnd (N));
return Skip;
when N_Attribute_Reference =>
Set_Do_Overflow_Check (N, False);
when N_Function_Call =>
Set_Do_Tag_Check (N, False);
when N_Op =>
Set_Do_Overflow_Check (N, False);
case Nkind (N) is
when N_Op_Divide =>
Set_Do_Division_Check (N, False);
when N_Op_And =>
Set_Do_Length_Check (N, False);
when N_Op_Mod =>
Set_Do_Division_Check (N, False);
when N_Op_Or =>
Set_Do_Length_Check (N, False);
when N_Op_Rem =>
Set_Do_Division_Check (N, False);
when N_Op_Xor =>
Set_Do_Length_Check (N, False);
when others =>
null;
end case;
when N_Or_Else =>
Traverse (Left_Opnd (N));
return Skip;
when N_Selected_Component =>
Set_Do_Discriminant_Check (N, False);
when N_Type_Conversion =>
Set_Do_Length_Check (N, False);
Set_Do_Tag_Check (N, False);
Set_Do_Overflow_Check (N, False);
when others =>
null;
end case;
return OK;
end Process;
-- Start of processing for Remove_Checks
begin
Traverse (Expr);
end Remove_Checks;
----------------------------
-- Selected_Length_Checks --
----------------------------
function Selected_Length_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Warn_Node : Node_Id) return Check_Result
is
Loc : constant Source_Ptr := Sloc (Ck_Node);
S_Typ : Entity_Id;
T_Typ : Entity_Id;
Expr_Actual : Node_Id;
Exptyp : Entity_Id;
Cond : Node_Id := Empty;
Do_Access : Boolean := False;
Wnode : Node_Id := Warn_Node;
Ret_Result : Check_Result := (Empty, Empty);
Num_Checks : Natural := 0;
procedure Add_Check (N : Node_Id);
-- Adds the action given to Ret_Result if N is non-Empty
function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
-- Comments required ???
function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
-- True for equal literals and for nodes that denote the same constant
-- entity, even if its value is not a static constant. This includes the
-- case of a discriminal reference within an init proc. Removes some
-- obviously superfluous checks.
function Length_E_Cond
(Exptyp : Entity_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id;
-- Returns expression to compute:
-- Typ'Length /= Exptyp'Length
function Length_N_Cond
(Expr : Node_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id;
-- Returns expression to compute:
-- Typ'Length /= Expr'Length
---------------
-- Add_Check --
---------------
procedure Add_Check (N : Node_Id) is
begin
if Present (N) then
-- For now, ignore attempt to place more than 2 checks ???
if Num_Checks = 2 then
return;
end if;
pragma Assert (Num_Checks <= 1);
Num_Checks := Num_Checks + 1;
Ret_Result (Num_Checks) := N;
end if;
end Add_Check;
------------------
-- Get_E_Length --
------------------
function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
SE : constant Entity_Id := Scope (E);
N : Node_Id;
E1 : Entity_Id := E;
begin
if Ekind (Scope (E)) = E_Record_Type
and then Has_Discriminants (Scope (E))
then
N := Build_Discriminal_Subtype_Of_Component (E);
if Present (N) then
Insert_Action (Ck_Node, N);
E1 := Defining_Identifier (N);
end if;
end if;
if Ekind (E1) = E_String_Literal_Subtype then
return
Make_Integer_Literal (Loc,
Intval => String_Literal_Length (E1));
elsif SE /= Standard_Standard
and then Ekind (Scope (SE)) = E_Protected_Type
and then Has_Discriminants (Scope (SE))
and then Has_Completion (Scope (SE))
and then not Inside_Init_Proc
then
-- If the type whose length is needed is a private component
-- constrained by a discriminant, we must expand the 'Length
-- attribute into an explicit computation, using the discriminal
-- of the current protected operation. This is because the actual
-- type of the prival is constructed after the protected opera-
-- tion has been fully expanded.
declare
Indx_Type : Node_Id;
Lo : Node_Id;
Hi : Node_Id;
Do_Expand : Boolean := False;
begin
Indx_Type := First_Index (E);
for J in 1 .. Indx - 1 loop
Next_Index (Indx_Type);
end loop;
Get_Index_Bounds (Indx_Type, Lo, Hi);
if Nkind (Lo) = N_Identifier
and then Ekind (Entity (Lo)) = E_In_Parameter
then
Lo := Get_Discriminal (E, Lo);
Do_Expand := True;
end if;
if Nkind (Hi) = N_Identifier
and then Ekind (Entity (Hi)) = E_In_Parameter
then
Hi := Get_Discriminal (E, Hi);
Do_Expand := True;
end if;
if Do_Expand then
if not Is_Entity_Name (Lo) then
Lo := Duplicate_Subexpr_No_Checks (Lo);
end if;
if not Is_Entity_Name (Hi) then
Lo := Duplicate_Subexpr_No_Checks (Hi);
end if;
N :=
Make_Op_Add (Loc,
Left_Opnd =>
Make_Op_Subtract (Loc,
Left_Opnd => Hi,
Right_Opnd => Lo),
Right_Opnd => Make_Integer_Literal (Loc, 1));
return N;
else
N :=
Make_Attribute_Reference (Loc,
Attribute_Name => Name_Length,
Prefix =>
New_Occurrence_Of (E1, Loc));
if Indx > 1 then
Set_Expressions (N, New_List (
Make_Integer_Literal (Loc, Indx)));
end if;
return N;
end if;
end;
else
N :=
Make_Attribute_Reference (Loc,
Attribute_Name => Name_Length,
Prefix =>
New_Occurrence_Of (E1, Loc));
if Indx > 1 then
Set_Expressions (N, New_List (
Make_Integer_Literal (Loc, Indx)));
end if;
return N;
end if;
end Get_E_Length;
------------------
-- Get_N_Length --
------------------
function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
begin
return
Make_Attribute_Reference (Loc,
Attribute_Name => Name_Length,
Prefix =>
Duplicate_Subexpr_No_Checks (N, Name_Req => True),
Expressions => New_List (
Make_Integer_Literal (Loc, Indx)));
end Get_N_Length;
-------------------
-- Length_E_Cond --
-------------------
function Length_E_Cond
(Exptyp : Entity_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id
is
begin
return
Make_Op_Ne (Loc,
Left_Opnd => Get_E_Length (Typ, Indx),
Right_Opnd => Get_E_Length (Exptyp, Indx));
end Length_E_Cond;
-------------------
-- Length_N_Cond --
-------------------
function Length_N_Cond
(Expr : Node_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id
is
begin
return
Make_Op_Ne (Loc,
Left_Opnd => Get_E_Length (Typ, Indx),
Right_Opnd => Get_N_Length (Expr, Indx));
end Length_N_Cond;
-----------------
-- Same_Bounds --
-----------------
function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
begin
return
(Nkind (L) = N_Integer_Literal
and then Nkind (R) = N_Integer_Literal
and then Intval (L) = Intval (R))
or else
(Is_Entity_Name (L)
and then Ekind (Entity (L)) = E_Constant
and then ((Is_Entity_Name (R)
and then Entity (L) = Entity (R))
or else
(Nkind (R) = N_Type_Conversion
and then Is_Entity_Name (Expression (R))
and then Entity (L) = Entity (Expression (R)))))
or else
(Is_Entity_Name (R)
and then Ekind (Entity (R)) = E_Constant
and then Nkind (L) = N_Type_Conversion
and then Is_Entity_Name (Expression (L))
and then Entity (R) = Entity (Expression (L)))
or else
(Is_Entity_Name (L)
and then Is_Entity_Name (R)
and then Entity (L) = Entity (R)
and then Ekind (Entity (L)) = E_In_Parameter
and then Inside_Init_Proc);
end Same_Bounds;
-- Start of processing for Selected_Length_Checks
begin
if not Full_Expander_Active then
return Ret_Result;
end if;
if Target_Typ = Any_Type
or else Target_Typ = Any_Composite
or else Raises_Constraint_Error (Ck_Node)
then
return Ret_Result;
end if;
if No (Wnode) then
Wnode := Ck_Node;
end if;
T_Typ := Target_Typ;
if No (Source_Typ) then
S_Typ := Etype (Ck_Node);
else
S_Typ := Source_Typ;
end if;
if S_Typ = Any_Type or else S_Typ = Any_Composite then
return Ret_Result;
end if;
if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
S_Typ := Designated_Type (S_Typ);
T_Typ := Designated_Type (T_Typ);
Do_Access := True;
-- A simple optimization for the null case
if Known_Null (Ck_Node) then
return Ret_Result;
end if;
end if;
if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
if Is_Constrained (T_Typ) then
-- The checking code to be generated will freeze the corresponding
-- array type. However, we must freeze the type now, so that the
-- freeze node does not appear within the generated if expression,
-- but ahead of it.
Freeze_Before (Ck_Node, T_Typ);
Expr_Actual := Get_Referenced_Object (Ck_Node);
Exptyp := Get_Actual_Subtype (Ck_Node);
if Is_Access_Type (Exptyp) then
Exptyp := Designated_Type (Exptyp);
end if;
-- String_Literal case. This needs to be handled specially be-
-- cause no index types are available for string literals. The
-- condition is simply:
-- T_Typ'Length = string-literal-length
if Nkind (Expr_Actual) = N_String_Literal
and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
then
Cond :=
Make_Op_Ne (Loc,
Left_Opnd => Get_E_Length (T_Typ, 1),
Right_Opnd =>
Make_Integer_Literal (Loc,
Intval =>
String_Literal_Length (Etype (Expr_Actual))));
-- General array case. Here we have a usable actual subtype for
-- the expression, and the condition is built from the two types
-- (Do_Length):
-- T_Typ'Length /= Exptyp'Length or else
-- T_Typ'Length (2) /= Exptyp'Length (2) or else
-- T_Typ'Length (3) /= Exptyp'Length (3) or else
-- ...
elsif Is_Constrained (Exptyp) then
declare
Ndims : constant Nat := Number_Dimensions (T_Typ);
L_Index : Node_Id;
R_Index : Node_Id;
L_Low : Node_Id;
L_High : Node_Id;
R_Low : Node_Id;
R_High : Node_Id;
L_Length : Uint;
R_Length : Uint;
Ref_Node : Node_Id;
begin
-- At the library level, we need to ensure that the type of
-- the object is elaborated before the check itself is
-- emitted. This is only done if the object is in the
-- current compilation unit, otherwise the type is frozen
-- and elaborated in its unit.
if Is_Itype (Exptyp)
and then
Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
and then
not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
and then In_Open_Scopes (Scope (Exptyp))
then
Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
Set_Itype (Ref_Node, Exptyp);
Insert_Action (Ck_Node, Ref_Node);
end if;
L_Index := First_Index (T_Typ);
R_Index := First_Index (Exptyp);
for Indx in 1 .. Ndims loop
if not (Nkind (L_Index) = N_Raise_Constraint_Error
or else
Nkind (R_Index) = N_Raise_Constraint_Error)
then
Get_Index_Bounds (L_Index, L_Low, L_High);
Get_Index_Bounds (R_Index, R_Low, R_High);
-- Deal with compile time length check. Note that we
-- skip this in the access case, because the access
-- value may be null, so we cannot know statically.
if not Do_Access
and then Compile_Time_Known_Value (L_Low)
and then Compile_Time_Known_Value (L_High)
and then Compile_Time_Known_Value (R_Low)
and then Compile_Time_Known_Value (R_High)
then
if Expr_Value (L_High) >= Expr_Value (L_Low) then
L_Length := Expr_Value (L_High) -
Expr_Value (L_Low) + 1;
else
L_Length := UI_From_Int (0);
end if;
if Expr_Value (R_High) >= Expr_Value (R_Low) then
R_Length := Expr_Value (R_High) -
Expr_Value (R_Low) + 1;
else
R_Length := UI_From_Int (0);
end if;
if L_Length > R_Length then
Add_Check
(Compile_Time_Constraint_Error
(Wnode, "too few elements for}??", T_Typ));
elsif L_Length < R_Length then
Add_Check
(Compile_Time_Constraint_Error
(Wnode, "too many elements for}??", T_Typ));
end if;
-- The comparison for an individual index subtype
-- is omitted if the corresponding index subtypes
-- statically match, since the result is known to
-- be true. Note that this test is worth while even
-- though we do static evaluation, because non-static
-- subtypes can statically match.
elsif not
Subtypes_Statically_Match
(Etype (L_Index), Etype (R_Index))
and then not
(Same_Bounds (L_Low, R_Low)
and then Same_Bounds (L_High, R_High))
then
Evolve_Or_Else
(Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
end if;
Next (L_Index);
Next (R_Index);
end if;
end loop;
end;
-- Handle cases where we do not get a usable actual subtype that
-- is constrained. This happens for example in the function call
-- and explicit dereference cases. In these cases, we have to get
-- the length or range from the expression itself, making sure we
-- do not evaluate it more than once.
-- Here Ck_Node is the original expression, or more properly the
-- result of applying Duplicate_Expr to the original tree, forcing
-- the result to be a name.
else
declare
Ndims : constant Nat := Number_Dimensions (T_Typ);
begin
-- Build the condition for the explicit dereference case
for Indx in 1 .. Ndims loop
Evolve_Or_Else
(Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
end loop;
end;
end if;
end if;
end if;
-- Construct the test and insert into the tree
if Present (Cond) then
if Do_Access then
Cond := Guard_Access (Cond, Loc, Ck_Node);
end if;
Add_Check
(Make_Raise_Constraint_Error (Loc,
Condition => Cond,
Reason => CE_Length_Check_Failed));
end if;
return Ret_Result;
end Selected_Length_Checks;
---------------------------
-- Selected_Range_Checks --
---------------------------
function Selected_Range_Checks
(Ck_Node : Node_Id;
Target_Typ : Entity_Id;
Source_Typ : Entity_Id;
Warn_Node : Node_Id) return Check_Result
is
Loc : constant Source_Ptr := Sloc (Ck_Node);
S_Typ : Entity_Id;
T_Typ : Entity_Id;
Expr_Actual : Node_Id;
Exptyp : Entity_Id;
Cond : Node_Id := Empty;
Do_Access : Boolean := False;
Wnode : Node_Id := Warn_Node;
Ret_Result : Check_Result := (Empty, Empty);
Num_Checks : Integer := 0;
procedure Add_Check (N : Node_Id);
-- Adds the action given to Ret_Result if N is non-Empty
function Discrete_Range_Cond
(Expr : Node_Id;
Typ : Entity_Id) return Node_Id;
-- Returns expression to compute:
-- Low_Bound (Expr) < Typ'First
-- or else
-- High_Bound (Expr) > Typ'Last
function Discrete_Expr_Cond
(Expr : Node_Id;
Typ : Entity_Id) return Node_Id;
-- Returns expression to compute:
-- Expr < Typ'First
-- or else
-- Expr > Typ'Last
function Get_E_First_Or_Last
(Loc : Source_Ptr;
E : Entity_Id;
Indx : Nat;
Nam : Name_Id) return Node_Id;
-- Returns an attribute reference
-- E'First or E'Last
-- with a source location of Loc.
--
-- Nam is Name_First or Name_Last, according to which attribute is
-- desired. If Indx is non-zero, it is passed as a literal in the
-- Expressions of the attribute reference (identifying the desired
-- array dimension).
function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
-- Returns expression to compute:
-- N'First or N'Last using Duplicate_Subexpr_No_Checks
function Range_E_Cond
(Exptyp : Entity_Id;
Typ : Entity_Id;
Indx : Nat)
return Node_Id;
-- Returns expression to compute:
-- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
function Range_Equal_E_Cond
(Exptyp : Entity_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id;
-- Returns expression to compute:
-- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
function Range_N_Cond
(Expr : Node_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id;
-- Return expression to compute:
-- Expr'First < Typ'First or else Expr'Last > Typ'Last
---------------
-- Add_Check --
---------------
procedure Add_Check (N : Node_Id) is
begin
if Present (N) then
-- For now, ignore attempt to place more than 2 checks ???
if Num_Checks = 2 then
return;
end if;
pragma Assert (Num_Checks <= 1);
Num_Checks := Num_Checks + 1;
Ret_Result (Num_Checks) := N;
end if;
end Add_Check;
-------------------------
-- Discrete_Expr_Cond --
-------------------------
function Discrete_Expr_Cond
(Expr : Node_Id;
Typ : Entity_Id) return Node_Id
is
begin
return
Make_Or_Else (Loc,
Left_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd =>
Convert_To (Base_Type (Typ),
Duplicate_Subexpr_No_Checks (Expr)),
Right_Opnd =>
Convert_To (Base_Type (Typ),
Get_E_First_Or_Last (Loc, Typ, 0, Name_First))),
Right_Opnd =>
Make_Op_Gt (Loc,
Left_Opnd =>
Convert_To (Base_Type (Typ),
Duplicate_Subexpr_No_Checks (Expr)),
Right_Opnd =>
Convert_To
(Base_Type (Typ),
Get_E_First_Or_Last (Loc, Typ, 0, Name_Last))));
end Discrete_Expr_Cond;
-------------------------
-- Discrete_Range_Cond --
-------------------------
function Discrete_Range_Cond
(Expr : Node_Id;
Typ : Entity_Id) return Node_Id
is
LB : Node_Id := Low_Bound (Expr);
HB : Node_Id := High_Bound (Expr);
Left_Opnd : Node_Id;
Right_Opnd : Node_Id;
begin
if Nkind (LB) = N_Identifier
and then Ekind (Entity (LB)) = E_Discriminant
then
LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
end if;
Left_Opnd :=
Make_Op_Lt (Loc,
Left_Opnd =>
Convert_To
(Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
Right_Opnd =>
Convert_To
(Base_Type (Typ),
Get_E_First_Or_Last (Loc, Typ, 0, Name_First)));
if Nkind (HB) = N_Identifier
and then Ekind (Entity (HB)) = E_Discriminant
then
HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
end if;
Right_Opnd :=
Make_Op_Gt (Loc,
Left_Opnd =>
Convert_To
(Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
Right_Opnd =>
Convert_To
(Base_Type (Typ),
Get_E_First_Or_Last (Loc, Typ, 0, Name_Last)));
return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
end Discrete_Range_Cond;
-------------------------
-- Get_E_First_Or_Last --
-------------------------
function Get_E_First_Or_Last
(Loc : Source_Ptr;
E : Entity_Id;
Indx : Nat;
Nam : Name_Id) return Node_Id
is
Exprs : List_Id;
begin
if Indx > 0 then
Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx)));
else
Exprs := No_List;
end if;
return Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (E, Loc),
Attribute_Name => Nam,
Expressions => Exprs);
end Get_E_First_Or_Last;
-----------------
-- Get_N_First --
-----------------
function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
begin
return
Make_Attribute_Reference (Loc,
Attribute_Name => Name_First,
Prefix =>
Duplicate_Subexpr_No_Checks (N, Name_Req => True),
Expressions => New_List (
Make_Integer_Literal (Loc, Indx)));
end Get_N_First;
----------------
-- Get_N_Last --
----------------
function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
begin
return
Make_Attribute_Reference (Loc,
Attribute_Name => Name_Last,
Prefix =>
Duplicate_Subexpr_No_Checks (N, Name_Req => True),
Expressions => New_List (
Make_Integer_Literal (Loc, Indx)));
end Get_N_Last;
------------------
-- Range_E_Cond --
------------------
function Range_E_Cond
(Exptyp : Entity_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id
is
begin
return
Make_Or_Else (Loc,
Left_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd =>
Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
Right_Opnd =>
Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
Right_Opnd =>
Make_Op_Gt (Loc,
Left_Opnd =>
Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
Right_Opnd =>
Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
end Range_E_Cond;
------------------------
-- Range_Equal_E_Cond --
------------------------
function Range_Equal_E_Cond
(Exptyp : Entity_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id
is
begin
return
Make_Or_Else (Loc,
Left_Opnd =>
Make_Op_Ne (Loc,
Left_Opnd =>
Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
Right_Opnd =>
Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
Right_Opnd =>
Make_Op_Ne (Loc,
Left_Opnd =>
Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
Right_Opnd =>
Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
end Range_Equal_E_Cond;
------------------
-- Range_N_Cond --
------------------
function Range_N_Cond
(Expr : Node_Id;
Typ : Entity_Id;
Indx : Nat) return Node_Id
is
begin
return
Make_Or_Else (Loc,
Left_Opnd =>
Make_Op_Lt (Loc,
Left_Opnd =>
Get_N_First (Expr, Indx),
Right_Opnd =>
Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
Right_Opnd =>
Make_Op_Gt (Loc,
Left_Opnd =>
Get_N_Last (Expr, Indx),
Right_Opnd =>
Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
end Range_N_Cond;
-- Start of processing for Selected_Range_Checks
begin
if not Full_Expander_Active then
return Ret_Result;
end if;
if Target_Typ = Any_Type
or else Target_Typ = Any_Composite
or else Raises_Constraint_Error (Ck_Node)
then
return Ret_Result;
end if;
if No (Wnode) then
Wnode := Ck_Node;
end if;
T_Typ := Target_Typ;
if No (Source_Typ) then
S_Typ := Etype (Ck_Node);
else
S_Typ := Source_Typ;
end if;
if S_Typ = Any_Type or else S_Typ = Any_Composite then
return Ret_Result;
end if;
-- The order of evaluating T_Typ before S_Typ seems to be critical
-- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
-- in, and since Node can be an N_Range node, it might be invalid.
-- Should there be an assert check somewhere for taking the Etype of
-- an N_Range node ???
if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
S_Typ := Designated_Type (S_Typ);
T_Typ := Designated_Type (T_Typ);
Do_Access := True;
-- A simple optimization for the null case
if Known_Null (Ck_Node) then
return Ret_Result;
end if;
end if;
-- For an N_Range Node, check for a null range and then if not
-- null generate a range check action.
if Nkind (Ck_Node) = N_Range then
-- There's no point in checking a range against itself
if Ck_Node = Scalar_Range (T_Typ) then
return Ret_Result;
end if;
declare
T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
T_HB : constant Node_Id := Type_High_Bound (T_Typ);
Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
LB : Node_Id := Low_Bound (Ck_Node);
HB : Node_Id := High_Bound (Ck_Node);
Known_LB : Boolean;
Known_HB : Boolean;
Null_Range : Boolean;
Out_Of_Range_L : Boolean;
Out_Of_Range_H : Boolean;
begin
-- Compute what is known at compile time
if Known_T_LB and Known_T_HB then
if Compile_Time_Known_Value (LB) then
Known_LB := True;
-- There's no point in checking that a bound is within its
-- own range so pretend that it is known in this case. First
-- deal with low bound.
elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
then
LB := T_LB;
Known_LB := True;
else
Known_LB := False;
end if;
-- Likewise for the high bound
if Compile_Time_Known_Value (HB) then
Known_HB := True;
elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
then
HB := T_HB;
Known_HB := True;
else
Known_HB := False;
end if;
end if;
-- Check for case where everything is static and we can do the
-- check at compile time. This is skipped if we have an access
-- type, since the access value may be null.
-- ??? This code can be improved since you only need to know that
-- the two respective bounds (LB & T_LB or HB & T_HB) are known at
-- compile time to emit pertinent messages.
if Known_T_LB and Known_T_HB and Known_LB and Known_HB
and not Do_Access
then
-- Floating-point case
if Is_Floating_Point_Type (S_Typ) then
Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
Out_Of_Range_L :=
(Expr_Value_R (LB) < Expr_Value_R (T_LB))
or else
(Expr_Value_R (LB) > Expr_Value_R (T_HB));
Out_Of_Range_H :=
(Expr_Value_R (HB) > Expr_Value_R (T_HB))
or else
(Expr_Value_R (HB) < Expr_Value_R (T_LB));
-- Fixed or discrete type case
else
Null_Range := Expr_Value (HB) < Expr_Value (LB);
Out_Of_Range_L :=
(Expr_Value (LB) < Expr_Value (T_LB))
or else
(Expr_Value (LB) > Expr_Value (T_HB));
Out_Of_Range_H :=
(Expr_Value (HB) > Expr_Value (T_HB))
or else
(Expr_Value (HB) < Expr_Value (T_LB));
end if;
if not Null_Range then
if Out_Of_Range_L then
if No (Warn_Node) then
Add_Check
(Compile_Time_Constraint_Error
(Low_Bound (Ck_Node),
"static value out of range of}??", T_Typ));
else
Add_Check
(Compile_Time_Constraint_Error
(Wnode,
"static range out of bounds of}??", T_Typ));
end if;
end if;
if Out_Of_Range_H then
if No (Warn_Node) then
Add_Check
(Compile_Time_Constraint_Error
(High_Bound (Ck_Node),
"static value out of range of}??", T_Typ));
else
Add_Check
(Compile_Time_Constraint_Error
(Wnode,
"static range out of bounds of}??", T_Typ));
end if;
end if;
end if;
else
declare
LB : Node_Id := Low_Bound (Ck_Node);
HB : Node_Id := High_Bound (Ck_Node);
begin
-- If either bound is a discriminant and we are within the
-- record declaration, it is a use of the discriminant in a
-- constraint of a component, and nothing can be checked
-- here. The check will be emitted within the init proc.
-- Before then, the discriminal has no real meaning.
-- Similarly, if the entity is a discriminal, there is no
-- check to perform yet.
-- The same holds within a discriminated synchronized type,
-- where the discriminant may constrain a component or an
-- entry family.
if Nkind (LB) = N_Identifier
and then Denotes_Discriminant (LB, True)
then
if Current_Scope = Scope (Entity (LB))
or else Is_Concurrent_Type (Current_Scope)
or else Ekind (Entity (LB)) /= E_Discriminant
then
return Ret_Result;
else
LB :=
New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
end if;
end if;
if Nkind (HB) = N_Identifier
and then Denotes_Discriminant (HB, True)
then
if Current_Scope = Scope (Entity (HB))
or else Is_Concurrent_Type (Current_Scope)
or else Ekind (Entity (HB)) /= E_Discriminant
then
return Ret_Result;
else
HB :=
New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
end if;
end if;
Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
Set_Paren_Count (Cond, 1);
Cond :=
Make_And_Then (Loc,
Left_Opnd =>
Make_Op_Ge (Loc,
Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
Right_Opnd => Cond);
end;
end if;
end;
elsif Is_Scalar_Type (S_Typ) then
-- This somewhat duplicates what Apply_Scalar_Range_Check does,
-- except the above simply sets a flag in the node and lets
-- gigi generate the check base on the Etype of the expression.
-- Sometimes, however we want to do a dynamic check against an
-- arbitrary target type, so we do that here.
if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
-- For literals, we can tell if the constraint error will be
-- raised at compile time, so we never need a dynamic check, but
-- if the exception will be raised, then post the usual warning,
-- and replace the literal with a raise constraint error
-- expression. As usual, skip this for access types
elsif Compile_Time_Known_Value (Ck_Node)
and then not Do_Access
then
declare
LB : constant Node_Id := Type_Low_Bound (T_Typ);
UB : constant Node_Id := Type_High_Bound (T_Typ);
Out_Of_Range : Boolean;
Static_Bounds : constant Boolean :=
Compile_Time_Known_Value (LB)
and Compile_Time_Known_Value (UB);
begin
-- Following range tests should use Sem_Eval routine ???
if Static_Bounds then
if Is_Floating_Point_Type (S_Typ) then
Out_Of_Range :=
(Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
or else
(Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
-- Fixed or discrete type
else
Out_Of_Range :=
Expr_Value (Ck_Node) < Expr_Value (LB)
or else
Expr_Value (Ck_Node) > Expr_Value (UB);
end if;
-- Bounds of the type are static and the literal is out of
-- range so output a warning message.
if Out_Of_Range then
if No (Warn_Node) then
Add_Check
(Compile_Time_Constraint_Error
(Ck_Node,
"static value out of range of}??", T_Typ));
else
Add_Check
(Compile_Time_Constraint_Error
(Wnode,
"static value out of range of}??", T_Typ));
end if;
end if;
else
Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
end if;
end;
-- Here for the case of a non-static expression, we need a runtime
-- check unless the source type range is guaranteed to be in the
-- range of the target type.
else
if not In_Subrange_Of (S_Typ, T_Typ) then
Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
end if;
end if;
end if;
if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
if Is_Constrained (T_Typ) then
Expr_Actual := Get_Referenced_Object (Ck_Node);
Exptyp := Get_Actual_Subtype (Expr_Actual);
if Is_Access_Type (Exptyp) then
Exptyp := Designated_Type (Exptyp);
end if;
-- String_Literal case. This needs to be handled specially be-
-- cause no index types are available for string literals. The
-- condition is simply:
-- T_Typ'Length = string-literal-length
if Nkind (Expr_Actual) = N_String_Literal then
null;
-- General array case. Here we have a usable actual subtype for
-- the expression, and the condition is built from the two types
-- T_Typ'First < Exptyp'First or else
-- T_Typ'Last > Exptyp'Last or else
-- T_Typ'First(1) < Exptyp'First(1) or else
-- T_Typ'Last(1) > Exptyp'Last(1) or else
-- ...
elsif Is_Constrained (Exptyp) then
declare
Ndims : constant Nat := Number_Dimensions (T_Typ);
L_Index : Node_Id;
R_Index : Node_Id;
begin
L_Index := First_Index (T_Typ);
R_Index := First_Index (Exptyp);
for Indx in 1 .. Ndims loop
if not (Nkind (L_Index) = N_Raise_Constraint_Error
or else
Nkind (R_Index) = N_Raise_Constraint_Error)
then
-- Deal with compile time length check. Note that we
-- skip this in the access case, because the access
-- value may be null, so we cannot know statically.
if not
Subtypes_Statically_Match
(Etype (L_Index), Etype (R_Index))
then
-- If the target type is constrained then we
-- have to check for exact equality of bounds
-- (required for qualified expressions).
if Is_Constrained (T_Typ) then
Evolve_Or_Else
(Cond,
Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
else
Evolve_Or_Else
(Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
end if;
end if;
Next (L_Index);
Next (R_Index);
end if;
end loop;
end;
-- Handle cases where we do not get a usable actual subtype that
-- is constrained. This happens for example in the function call
-- and explicit dereference cases. In these cases, we have to get
-- the length or range from the expression itself, making sure we
-- do not evaluate it more than once.
-- Here Ck_Node is the original expression, or more properly the
-- result of applying Duplicate_Expr to the original tree,
-- forcing the result to be a name.
else
declare
Ndims : constant Nat := Number_Dimensions (T_Typ);
begin
-- Build the condition for the explicit dereference case
for Indx in 1 .. Ndims loop
Evolve_Or_Else
(Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
end loop;
end;
end if;
else
-- For a conversion to an unconstrained array type, generate an
-- Action to check that the bounds of the source value are within
-- the constraints imposed by the target type (RM 4.6(38)). No
-- check is needed for a conversion to an access to unconstrained
-- array type, as 4.6(24.15/2) requires the designated subtypes
-- of the two access types to statically match.
if Nkind (Parent (Ck_Node)) = N_Type_Conversion
and then not Do_Access
then
declare
Opnd_Index : Node_Id;
Targ_Index : Node_Id;
Opnd_Range : Node_Id;
begin
Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
Targ_Index := First_Index (T_Typ);
while Present (Opnd_Index) loop
-- If the index is a range, use its bounds. If it is an
-- entity (as will be the case if it is a named subtype
-- or an itype created for a slice) retrieve its range.
if Is_Entity_Name (Opnd_Index)
and then Is_Type (Entity (Opnd_Index))
then
Opnd_Range := Scalar_Range (Entity (Opnd_Index));
else
Opnd_Range := Opnd_Index;
end if;
if Nkind (Opnd_Range) = N_Range then
if Is_In_Range
(Low_Bound (Opnd_Range), Etype (Targ_Index),
Assume_Valid => True)
and then
Is_In_Range
(High_Bound (Opnd_Range), Etype (Targ_Index),
Assume_Valid => True)
then
null;
-- If null range, no check needed
elsif
Compile_Time_Known_Value (High_Bound (Opnd_Range))
and then
Compile_Time_Known_Value (Low_Bound (Opnd_Range))
and then
Expr_Value (High_Bound (Opnd_Range)) <
Expr_Value (Low_Bound (Opnd_Range))
then
null;
elsif Is_Out_Of_Range
(Low_Bound (Opnd_Range), Etype (Targ_Index),
Assume_Valid => True)
or else
Is_Out_Of_Range
(High_Bound (Opnd_Range), Etype (Targ_Index),
Assume_Valid => True)
then
Add_Check
(Compile_Time_Constraint_Error
(Wnode, "value out of range of}??", T_Typ));
else
Evolve_Or_Else
(Cond,
Discrete_Range_Cond
(Opnd_Range, Etype (Targ_Index)));
end if;
end if;
Next_Index (Opnd_Index);
Next_Index (Targ_Index);
end loop;
end;
end if;
end if;
end if;
-- Construct the test and insert into the tree
if Present (Cond) then
if Do_Access then
Cond := Guard_Access (Cond, Loc, Ck_Node);
end if;
Add_Check
(Make_Raise_Constraint_Error (Loc,
Condition => Cond,
Reason => CE_Range_Check_Failed));
end if;
return Ret_Result;
end Selected_Range_Checks;
-------------------------------
-- Storage_Checks_Suppressed --
-------------------------------
function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Storage_Check);
else
return Scope_Suppress.Suppress (Storage_Check);
end if;
end Storage_Checks_Suppressed;
---------------------------
-- Tag_Checks_Suppressed --
---------------------------
function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E)
and then Checks_May_Be_Suppressed (E)
then
return Is_Check_Suppressed (E, Tag_Check);
end if;
return Scope_Suppress.Suppress (Tag_Check);
end Tag_Checks_Suppressed;
--------------------------
-- Validity_Check_Range --
--------------------------
procedure Validity_Check_Range (N : Node_Id) is
begin
if Validity_Checks_On and Validity_Check_Operands then
if Nkind (N) = N_Range then
Ensure_Valid (Low_Bound (N));
Ensure_Valid (High_Bound (N));
end if;
end if;
end Validity_Check_Range;
--------------------------------
-- Validity_Checks_Suppressed --
--------------------------------
function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
begin
if Present (E) and then Checks_May_Be_Suppressed (E) then
return Is_Check_Suppressed (E, Validity_Check);
else
return Scope_Suppress.Suppress (Validity_Check);
end if;
end Validity_Checks_Suppressed;
end Checks;