------------------------------------------------------------------------------
-- --
--- GNAT RUNTIME COMPONENTS --
+-- GNAT RUN-TIME COMPONENTS --
-- --
--- G N A T . T A B L E --
+-- G N A T . T A B L E --
-- --
-- B o d y --
-- --
--- $Revision: 1.8 $
--- --
--- Copyright (C) 1998-2001 Ada Core Technologies, Inc. --
+-- Copyright (C) 1998-2007, AdaCore --
-- --
-- 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- --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
--- GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com). --
+-- GNAT was originally developed by the GNAT team at New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-with System; use System;
+with System; use System;
+with System.Memory; use System.Memory;
+
+with Ada.Unchecked_Conversion;
package body GNAT.Table is
-- ensures that we initially allocate the table.
Last_Val : Integer;
- -- Current value of Last.
-
- type size_t is new Integer;
+ -- Current value of Last
-----------------------
-- Local Subprograms --
-- in Max. Works correctly to do an initial allocation if the table
-- is currently null.
+ pragma Warnings (Off);
+ -- Turn off warnings. The following unchecked conversions are only used
+ -- internally in this package, and cannot never result in any instances
+ -- of improperly aliased pointers for the client of the package.
+
+ function To_Address is new Ada.Unchecked_Conversion (Table_Ptr, Address);
+ function To_Pointer is new Ada.Unchecked_Conversion (Address, Table_Ptr);
+
+ pragma Warnings (On);
+
--------------
-- Allocate --
--------------
procedure Append (New_Val : Table_Component_Type) is
begin
- Increment_Last;
- Table (Table_Index_Type (Last_Val)) := New_Val;
+ Set_Item (Table_Index_Type (Last_Val + 1), New_Val);
end Append;
--------------------
----------
procedure Free is
- procedure free (T : Table_Ptr);
- pragma Import (C, free);
-
begin
- free (Table);
+ Free (To_Address (Table));
Table := null;
Length := 0;
end Free;
----------
procedure Init is
- Old_Length : Integer := Length;
+ Old_Length : constant Integer := Length;
begin
Last_Val := Min - 1;
----------------
procedure Reallocate is
-
- function realloc
- (memblock : Table_Ptr;
- size : size_t)
- return Table_Ptr;
- pragma Import (C, realloc);
-
- function malloc
- (size : size_t)
- return Table_Ptr;
- pragma Import (C, malloc);
-
New_Size : size_t;
begin
(Table_Type'Component_Size / Storage_Unit));
if Table = null then
- Table := malloc (New_Size);
+ Table := To_Pointer (Alloc (New_Size));
elsif New_Size > 0 then
Table :=
- realloc
- (memblock => Table,
- size => New_Size);
+ To_Pointer (Realloc (Ptr => To_Address (Table),
+ Size => New_Size));
end if;
if Length /= 0 and then Table = null then
--------------
procedure Set_Item
- (Index : Table_Index_Type;
- Item : Table_Component_Type)
+ (Index : Table_Index_Type;
+ Item : Table_Component_Type)
is
+ -- If Item is a value within the current allocation, and we are going to
+ -- reallocate, then we must preserve an intermediate copy here before
+ -- calling Increment_Last. Otherwise, if Table_Component_Type is passed
+ -- by reference, we are going to end up copying from storage that might
+ -- have been deallocated from Increment_Last calling Reallocate.
+
+ subtype Allocated_Table_T is
+ Table_Type (Table'First .. Table_Index_Type (Max + 1));
+ -- A constrained table subtype one element larger than the currently
+ -- allocated table.
+
+ Allocated_Table_Address : constant System.Address :=
+ Table.all'Address;
+ -- Used for address clause below (we can't use non-static expression
+ -- Table.all'Address directly in the clause because some older versions
+ -- of the compiler do not allow it).
+
+ Allocated_Table : Allocated_Table_T;
+ pragma Import (Ada, Allocated_Table);
+ pragma Suppress (Range_Check, On => Allocated_Table);
+ for Allocated_Table'Address use Allocated_Table_Address;
+ -- Allocated_Table represents the currently allocated array, plus
+ -- one element (the supplementary element is used to have a
+ -- convenient way of computing the address just past the end of the
+ -- current allocation). Range checks are suppressed because this unit
+ -- uses direct calls to System.Memory for allocation, and this can
+ -- yield misaligned storage (and we cannot rely on the bootstrap
+ -- compiler supporting specifically disabling alignment checks, so we
+ -- need to suppress all range checks). It is safe to suppress this check
+ -- here because we know that a (possibly misaligned) object of that type
+ -- does actually exist at that address.
+ -- ??? We should really improve the allocation circuitry here to
+ -- guarantee proper alignment.
+
+ Need_Realloc : constant Boolean := Integer (Index) > Max;
+ -- True if this operation requires storage reallocation (which may
+ -- involve moving table contents around).
+
begin
- if Integer (Index) > Max then
- Set_Last (Index);
- end if;
+ -- If we're going to reallocate, check whether Item references an
+ -- element of the currently allocated table.
+
+ if Need_Realloc
+ and then Allocated_Table'Address <= Item'Address
+ and then Item'Address <
+ Allocated_Table (Table_Index_Type (Max + 1))'Address
+ then
+ -- If so, save a copy on the stack because Increment_Last will
+ -- reallocate storage and might deallocate the current table.
+
+ declare
+ Item_Copy : constant Table_Component_Type := Item;
+ begin
+ Set_Last (Index);
+ Table (Index) := Item_Copy;
+ end;
+
+ else
+ -- Here we know that either we won't reallocate (case of Index < Max)
+ -- or that Item is not in the currently allocated table.
+
+ if Integer (Index) > Last_Val then
+ Set_Last (Index);
+ end if;
- Table (Index) := Item;
+ Table (Index) := Item;
+ end if;
end Set_Item;
--------------
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