1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2007, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
32 ------------------------------------------------------------------------------
34 with Debug; use Debug;
36 with Output; use Output;
37 with System; use System;
38 with Tree_IO; use Tree_IO;
40 with System.Memory; use System.Memory;
42 with Unchecked_Conversion;
44 pragma Elaborate_All (Output);
49 Min : constant Int := Int (Table_Low_Bound);
50 -- Subscript of the minimum entry in the currently allocated table
53 -- Number of entries in currently allocated table. The value of zero
54 -- ensures that we initially allocate the table.
56 -----------------------
57 -- Local Subprograms --
58 -----------------------
61 -- Reallocate the existing table according to the current value stored
62 -- in Max. Works correctly to do an initial allocation if the table
65 function Tree_Get_Table_Address return Address;
66 -- Return Null_Address if the table length is zero,
67 -- Table (First)'Address if not.
69 pragma Warnings (Off);
70 -- Turn off warnings. The following unchecked conversions are only used
71 -- internally in this package, and cannot never result in any instances
72 -- of improperly aliased pointers for the client of the package.
74 function To_Address is new Unchecked_Conversion (Table_Ptr, Address);
75 function To_Pointer is new Unchecked_Conversion (Address, Table_Ptr);
83 procedure Append (New_Val : Table_Component_Type) is
85 Set_Item (Table_Index_Type (Last_Val + 1), New_Val);
92 procedure Decrement_Last is
94 Last_Val := Last_Val - 1;
103 Free (To_Address (Table));
112 procedure Increment_Last is
114 Last_Val := Last_Val + 1;
116 if Last_Val > Max then
126 Old_Length : constant Int := Length;
131 Max := Min + (Table_Initial * Table_Factor) - 1;
132 Length := Max - Min + 1;
134 -- If table is same size as before (happens when table is never
135 -- expanded which is a common case), then simply reuse it. Note
136 -- that this also means that an explicit Init call right after
137 -- the implicit one in the package body is harmless.
139 if Old_Length = Length then
142 -- Otherwise we can use Reallocate to get a table of the right size.
143 -- Note that Reallocate works fine to allocate a table of the right
144 -- initial size when it is first allocated.
155 function Last return Table_Index_Type is
157 return Table_Index_Type (Last_Val);
164 procedure Reallocate is
165 New_Size : Memory.size_t;
168 if Max < Last_Val then
169 pragma Assert (not Locked);
171 -- Make sure that we have at least the initial allocation. This
172 -- is needed in cases where a zero length table is written out.
174 Length := Int'Max (Length, Table_Initial);
176 -- Now increment table length until it is sufficiently large. Use
177 -- the increment value or 10, which ever is larger (the reason
178 -- for the use of 10 here is to ensure that the table does really
179 -- increase in size (which would not be the case for a table of
180 -- length 10 increased by 3% for instance).
182 while Max < Last_Val loop
183 Length := Int'Max (Length * (100 + Table_Increment) / 100,
185 Max := Min + Length - 1;
189 Write_Str ("--> Allocating new ");
190 Write_Str (Table_Name);
191 Write_Str (" table, size = ");
192 Write_Int (Max - Min + 1);
198 Memory.size_t ((Max - Min + 1) *
199 (Table_Type'Component_Size / Storage_Unit));
202 Table := To_Pointer (Alloc (New_Size));
204 elsif New_Size > 0 then
206 To_Pointer (Realloc (Ptr => To_Address (Table),
210 if Length /= 0 and then Table = null then
212 Write_Str ("available memory exhausted");
215 raise Unrecoverable_Error;
226 Length := Last_Val - Int (Table_Low_Bound) + 1;
235 procedure Restore (T : Saved_Table) is
237 Free (To_Address (Table));
238 Last_Val := T.Last_Val;
241 Length := Max - Min + 1;
248 function Save return Saved_Table is
252 Res.Last_Val := Last_Val;
267 (Index : Table_Index_Type;
268 Item : Table_Component_Type)
270 -- If Item is a value within the current allocation, and we are going
271 -- to reallocate, then we must preserve an intermediate copy here
272 -- before calling Increment_Last. Otherwise, if Table_Component_Type
273 -- is passed by reference, we are going to end up copying from
274 -- storage that might have been deallocated from Increment_Last
275 -- calling Reallocate.
277 subtype Allocated_Table_T is
278 Table_Type (Table'First .. Table_Index_Type (Max + 1));
279 -- A constrained table subtype one element larger than the currently
282 Allocated_Table_Address : constant System.Address :=
284 -- Used for address clause below (we can't use non-static expression
285 -- Table.all'Address directly in the clause because some older
286 -- versions of the compiler do not allow it).
288 Allocated_Table : Allocated_Table_T;
289 pragma Import (Ada, Allocated_Table);
290 pragma Suppress (Range_Check, On => Allocated_Table);
291 for Allocated_Table'Address use Allocated_Table_Address;
292 -- Allocated_Table represents the currently allocated array, plus one
293 -- element (the supplementary element is used to have a convenient
294 -- way of computing the address just past the end of the current
295 -- allocation). Range checks are suppressed because this unit
296 -- uses direct calls to System.Memory for allocation, and this can
297 -- yield misaligned storage (and we cannot rely on the bootstrap
298 -- compiler supporting specifically disabling alignment cheks, so we
299 -- need to suppress all range checks). It is safe to suppress this
300 -- check here because we know that a (possibly misaligned) object
301 -- of that type does actually exist at that address.
302 -- ??? We should really improve the allocation circuitry here to
303 -- guarantee proper alignment.
305 Need_Realloc : constant Boolean := Int (Index) > Max;
306 -- True if this operation requires storage reallocation (which may
307 -- involve moving table contents around).
310 -- If we're going to reallocate, check wheter Item references an
311 -- element of the currently allocated table.
314 and then Allocated_Table'Address <= Item'Address
315 and then Item'Address <
316 Allocated_Table (Table_Index_Type (Max + 1))'Address
318 -- If so, save a copy on the stack because Increment_Last will
319 -- reallocate storage and might deallocate the current table.
322 Item_Copy : constant Table_Component_Type := Item;
325 Table (Index) := Item_Copy;
329 -- Here we know that either we won't reallocate (case of Index <
330 -- Max) or that Item is not in the currently allocated table.
332 if Int (Index) > Last_Val then
336 Table (Index) := Item;
344 procedure Set_Last (New_Val : Table_Index_Type) is
346 if Int (New_Val) < Last_Val then
347 Last_Val := Int (New_Val);
350 Last_Val := Int (New_Val);
352 if Last_Val > Max then
358 ----------------------------
359 -- Tree_Get_Table_Address --
360 ----------------------------
362 function Tree_Get_Table_Address return Address is
367 return Table (First)'Address;
369 end Tree_Get_Table_Address;
375 -- Note: we allocate only the space required to accommodate the data
376 -- actually written, which means that a Tree_Write/Tree_Read sequence
377 -- does an implicit Release.
379 procedure Tree_Read is
383 Length := Max - Min + 1;
387 (Tree_Get_Table_Address,
388 (Last_Val - Int (First) + 1) *
389 Table_Type'Component_Size / Storage_Unit);
396 -- Note: we write out only the currently valid data, not the entire
397 -- contents of the allocated array. See note above on Tree_Read.
399 procedure Tree_Write is
401 Tree_Write_Int (Int (Last));
403 (Tree_Get_Table_Address,
404 (Last_Val - Int (First) + 1) *
405 Table_Type'Component_Size / Storage_Unit);