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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- T A B L E --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
10 -- --
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. --
17 -- --
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. --
21 -- --
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/>. --
26 -- --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
29 -- --
30 ------------------------------------------------------------------------------
32 with Debug; use Debug;
33 with Opt; use Opt;
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);
44 package body Table is
45 package body Table is
47 Min : constant Int := Int (Table_Low_Bound);
48 -- Subscript of the minimum entry in the currently allocated table
50 Length : Int := 0;
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 -----------------------
58 procedure Reallocate;
59 -- Reallocate the existing table according to the current value stored
60 -- in Max. Works correctly to do an initial allocation if the table
61 -- is currently null.
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);
75 pragma Warnings (On);
77 ------------
78 -- Append --
79 ------------
81 procedure Append (New_Val : Table_Component_Type) is
82 begin
83 Set_Item (Table_Index_Type (Last_Val + 1), New_Val);
84 end Append;
86 ----------------
87 -- Append_All --
88 ----------------
90 procedure Append_All (New_Vals : Table_Type) is
91 begin
92 for J in New_Vals'Range loop
93 Append (New_Vals (J));
94 end loop;
95 end Append_All;
97 --------------------
98 -- Decrement_Last --
99 --------------------
101 procedure Decrement_Last is
102 begin
103 Last_Val := Last_Val - 1;
104 end Decrement_Last;
106 ----------
107 -- Free --
108 ----------
110 procedure Free is
111 begin
112 Free (To_Address (Table));
113 Table := null;
114 Length := 0;
115 end Free;
117 --------------------
118 -- Increment_Last --
119 --------------------
121 procedure Increment_Last is
122 begin
123 Last_Val := Last_Val + 1;
125 if Last_Val > Max then
126 Reallocate;
127 end if;
128 end Increment_Last;
130 ----------
131 -- Init --
132 ----------
134 procedure Init is
135 Old_Length : constant Int := Length;
137 begin
138 Locked := False;
139 Last_Val := Min - 1;
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
149 return;
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.
155 else
156 Reallocate;
157 end if;
158 end Init;
160 ----------
161 -- Last --
162 ----------
164 function Last return Table_Index_Type is
165 begin
166 return Table_Index_Type (Last_Val);
167 end Last;
169 ----------------
170 -- Reallocate --
171 ----------------
173 procedure Reallocate is
174 New_Size : Memory.size_t;
176 begin
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,
193 Length + 10);
194 Max := Min + Length - 1;
195 end loop;
197 if Debug_Flag_D then
198 Write_Str ("--> Allocating new ");
199 Write_Str (Table_Name);
200 Write_Str (" table, size = ");
201 Write_Int (Max - Min + 1);
202 Write_Eol;
203 end if;
204 end if;
206 New_Size :=
207 Memory.size_t ((Max - Min + 1) *
208 (Table_Type'Component_Size / Storage_Unit));
210 if Table = null then
211 Table := To_Pointer (Alloc (New_Size));
213 elsif New_Size > 0 then
214 Table :=
215 To_Pointer (Realloc (Ptr => To_Address (Table),
216 Size => New_Size));
217 end if;
219 if Length /= 0 and then Table = null then
220 Set_Standard_Error;
221 Write_Str ("available memory exhausted");
222 Write_Eol;
223 Set_Standard_Output;
224 raise Unrecoverable_Error;
225 end if;
227 end Reallocate;
229 -------------
230 -- Release --
231 -------------
233 procedure Release is
234 begin
235 Length := Last_Val - Int (Table_Low_Bound) + 1;
236 Max := Last_Val;
237 Reallocate;
238 end Release;
240 -------------
241 -- Restore --
242 -------------
244 procedure Restore (T : Saved_Table) is
245 begin
246 Free (To_Address (Table));
247 Last_Val := T.Last_Val;
248 Max := T.Max;
249 Table := T.Table;
250 Length := Max - Min + 1;
251 end Restore;
253 ----------
254 -- Save --
255 ----------
257 function Save return Saved_Table is
258 Res : Saved_Table;
260 begin
261 Res.Last_Val := Last_Val;
262 Res.Max := Max;
263 Res.Table := Table;
265 Table := null;
266 Length := 0;
267 Init;
268 return Res;
269 end Save;
271 --------------
272 -- Set_Item --
273 --------------
275 procedure Set_Item
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
289 -- allocated table.
291 Allocated_Table_Address : constant System.Address :=
292 Table.all'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).
318 begin
319 -- If we're going to reallocate, check whether Item references an
320 -- element of the currently allocated table.
322 if Need_Realloc
323 and then Allocated_Table'Address <= Item'Address
324 and then Item'Address <
325 Allocated_Table (Table_Index_Type (Max + 1))'Address
326 then
327 -- If so, save a copy on the stack because Increment_Last will
328 -- reallocate storage and might deallocate the current table.
330 declare
331 Item_Copy : constant Table_Component_Type := Item;
332 begin
333 Set_Last (Index);
334 Table (Index) := Item_Copy;
335 end;
337 else
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
342 Set_Last (Index);
343 end if;
345 Table (Index) := Item;
346 end if;
347 end Set_Item;
349 --------------
350 -- Set_Last --
351 --------------
353 procedure Set_Last (New_Val : Table_Index_Type) is
354 begin
355 if Int (New_Val) < Last_Val then
356 Last_Val := Int (New_Val);
358 else
359 Last_Val := Int (New_Val);
361 if Last_Val > Max then
362 Reallocate;
363 end if;
364 end if;
365 end Set_Last;
367 ----------------------------
368 -- Tree_Get_Table_Address --
369 ----------------------------
371 function Tree_Get_Table_Address return Address is
372 begin
373 if Length = 0 then
374 return Null_Address;
375 else
376 return Table (First)'Address;
377 end if;
378 end Tree_Get_Table_Address;
380 ---------------
381 -- Tree_Read --
382 ---------------
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
389 begin
390 Tree_Read_Int (Max);
391 Last_Val := Max;
392 Length := Max - Min + 1;
393 Reallocate;
395 Tree_Read_Data
396 (Tree_Get_Table_Address,
397 (Last_Val - Int (First) + 1) *
398 Table_Type'Component_Size / Storage_Unit);
399 end Tree_Read;
401 ----------------
402 -- Tree_Write --
403 ----------------
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
409 begin
410 Tree_Write_Int (Int (Last));
411 Tree_Write_Data
412 (Tree_Get_Table_Address,
413 (Last_Val - Int (First) + 1) *
414 Table_Type'Component_Size / Storage_Unit);
415 end Tree_Write;
417 begin
418 Init;
419 end Table;
420 end Table;