1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2009, 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 3, 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. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 with Debug; use Debug;
34 with Output; use Output;
35 with System; use System;
36 with Tree_IO; use Tree_IO;
38 with System.Memory; use System.Memory;
40 with Unchecked_Conversion;
42 pragma Elaborate_All (Output);
47 Min : constant Int := Int (Table_Low_Bound);
48 -- Subscript of the minimum entry in the currently allocated table
51 -- Number of entries in currently allocated table. The value of zero
52 -- ensures that we initially allocate the table.
54 -----------------------
55 -- Local Subprograms --
56 -----------------------
59 -- Reallocate the existing table according to the current value stored
60 -- in Max. Works correctly to do an initial allocation if the table
63 function Tree_Get_Table_Address return Address;
64 -- Return Null_Address if the table length is zero,
65 -- Table (First)'Address if not.
67 pragma Warnings (Off);
68 -- Turn off warnings. The following unchecked conversions are only used
69 -- internally in this package, and cannot never result in any instances
70 -- of improperly aliased pointers for the client of the package.
72 function To_Address is new Unchecked_Conversion (Table_Ptr, Address);
73 function To_Pointer is new Unchecked_Conversion (Address, Table_Ptr);
81 procedure Append (New_Val : Table_Component_Type) is
83 Set_Item (Table_Index_Type (Last_Val + 1), New_Val);
90 procedure Append_All (New_Vals : Table_Type) is
92 for J in New_Vals'Range loop
93 Append (New_Vals (J));
101 procedure Decrement_Last is
103 Last_Val := Last_Val - 1;
112 Free (To_Address (Table));
121 procedure Increment_Last is
123 Last_Val := Last_Val + 1;
125 if Last_Val > Max then
135 Old_Length : constant Int := Length;
140 Max := Min + (Table_Initial * Table_Factor) - 1;
141 Length := Max - Min + 1;
143 -- If table is same size as before (happens when table is never
144 -- expanded which is a common case), then simply reuse it. Note
145 -- that this also means that an explicit Init call right after
146 -- the implicit one in the package body is harmless.
148 if Old_Length = Length then
151 -- Otherwise we can use Reallocate to get a table of the right size.
152 -- Note that Reallocate works fine to allocate a table of the right
153 -- initial size when it is first allocated.
164 function Last return Table_Index_Type is
166 return Table_Index_Type (Last_Val);
173 procedure Reallocate is
174 New_Size : Memory.size_t;
177 if Max < Last_Val then
178 pragma Assert (not Locked);
180 -- Make sure that we have at least the initial allocation. This
181 -- is needed in cases where a zero length table is written out.
183 Length := Int'Max (Length, Table_Initial);
185 -- Now increment table length until it is sufficiently large. Use
186 -- the increment value or 10, which ever is larger (the reason
187 -- for the use of 10 here is to ensure that the table does really
188 -- increase in size (which would not be the case for a table of
189 -- length 10 increased by 3% for instance).
191 while Max < Last_Val loop
192 Length := Int'Max (Length * (100 + Table_Increment) / 100,
194 Max := Min + Length - 1;
198 Write_Str ("--> Allocating new ");
199 Write_Str (Table_Name);
200 Write_Str (" table, size = ");
201 Write_Int (Max - Min + 1);
207 Memory.size_t ((Max - Min + 1) *
208 (Table_Type'Component_Size / Storage_Unit));
211 Table := To_Pointer (Alloc (New_Size));
213 elsif New_Size > 0 then
215 To_Pointer (Realloc (Ptr => To_Address (Table),
219 if Length /= 0 and then Table = null then
221 Write_Str ("available memory exhausted");
224 raise Unrecoverable_Error;
235 Length := Last_Val - Int (Table_Low_Bound) + 1;
244 procedure Restore (T : Saved_Table) is
246 Free (To_Address (Table));
247 Last_Val := T.Last_Val;
250 Length := Max - Min + 1;
257 function Save return Saved_Table is
261 Res.Last_Val := Last_Val;
276 (Index : Table_Index_Type;
277 Item : Table_Component_Type)
279 -- If Item is a value within the current allocation, and we are going
280 -- to reallocate, then we must preserve an intermediate copy here
281 -- before calling Increment_Last. Otherwise, if Table_Component_Type
282 -- is passed by reference, we are going to end up copying from
283 -- storage that might have been deallocated from Increment_Last
284 -- calling Reallocate.
286 subtype Allocated_Table_T is
287 Table_Type (Table'First .. Table_Index_Type (Max + 1));
288 -- A constrained table subtype one element larger than the currently
291 Allocated_Table_Address : constant System.Address :=
293 -- Used for address clause below (we can't use non-static expression
294 -- Table.all'Address directly in the clause because some older
295 -- versions of the compiler do not allow it).
297 Allocated_Table : Allocated_Table_T;
298 pragma Import (Ada, Allocated_Table);
299 pragma Suppress (Range_Check, On => Allocated_Table);
300 for Allocated_Table'Address use Allocated_Table_Address;
301 -- Allocated_Table represents the currently allocated array, plus one
302 -- element (the supplementary element is used to have a convenient
303 -- way of computing the address just past the end of the current
304 -- allocation). Range checks are suppressed because this unit
305 -- uses direct calls to System.Memory for allocation, and this can
306 -- yield misaligned storage (and we cannot rely on the bootstrap
307 -- compiler supporting specifically disabling alignment checks, so we
308 -- need to suppress all range checks). It is safe to suppress this
309 -- check here because we know that a (possibly misaligned) object
310 -- of that type does actually exist at that address.
311 -- ??? We should really improve the allocation circuitry here to
312 -- guarantee proper alignment.
314 Need_Realloc : constant Boolean := Int (Index) > Max;
315 -- True if this operation requires storage reallocation (which may
316 -- involve moving table contents around).
319 -- If we're going to reallocate, check whether Item references an
320 -- element of the currently allocated table.
323 and then Allocated_Table'Address <= Item'Address
324 and then Item'Address <
325 Allocated_Table (Table_Index_Type (Max + 1))'Address
327 -- If so, save a copy on the stack because Increment_Last will
328 -- reallocate storage and might deallocate the current table.
331 Item_Copy : constant Table_Component_Type := Item;
334 Table (Index) := Item_Copy;
338 -- Here we know that either we won't reallocate (case of Index <
339 -- Max) or that Item is not in the currently allocated table.
341 if Int (Index) > Last_Val then
345 Table (Index) := Item;
353 procedure Set_Last (New_Val : Table_Index_Type) is
355 if Int (New_Val) < Last_Val then
356 Last_Val := Int (New_Val);
359 Last_Val := Int (New_Val);
361 if Last_Val > Max then
367 ----------------------------
368 -- Tree_Get_Table_Address --
369 ----------------------------
371 function Tree_Get_Table_Address return Address is
376 return Table (First)'Address;
378 end Tree_Get_Table_Address;
384 -- Note: we allocate only the space required to accommodate the data
385 -- actually written, which means that a Tree_Write/Tree_Read sequence
386 -- does an implicit Release.
388 procedure Tree_Read is
392 Length := Max - Min + 1;
396 (Tree_Get_Table_Address,
397 (Last_Val - Int (First) + 1) *
398 Table_Type'Component_Size / Storage_Unit);
405 -- Note: we write out only the currently valid data, not the entire
406 -- contents of the allocated array. See note above on Tree_Read.
408 procedure Tree_Write is
410 Tree_Write_Int (Int (Last));
412 (Tree_Get_Table_Address,
413 (Last_Val - Int (First) + 1) *
414 Table_Type'Component_Size / Storage_Unit);