1/* Functions to support a pool of allocatable objects.
2   Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2006
3   Free Software Foundation, Inc.
4   Contributed by Daniel Berlin <dan@cgsoftware.com>
5
6This file is part of GCC.
7
8GCC is free software; you can redistribute it and/or modify it under
9the terms of the GNU General Public License as published by the Free
10Software Foundation; either version 2, or (at your option) any later
11version.
12
13GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14WARRANTY; without even the implied warranty of MERCHANTABILITY or
15FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
16for more details.
17
18You should have received a copy of the GNU General Public License
19along with GCC; see the file COPYING.  If not, write to the Free
20Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
2102110-1301, USA.  */
22
23#include "config.h"
24#include "system.h"
25#include "alloc-pool.h"
26#include "hashtab.h"
27
28#define align_eight(x) (((x+7) >> 3) << 3)
29
30/* The internal allocation object.  */
31typedef struct allocation_object_def
32{
33#ifdef ENABLE_CHECKING
34  /* The ID of alloc pool which the object was allocated from.  */
35  ALLOC_POOL_ID_TYPE id;
36#endif
37
38  union
39    {
40      /* The data of the object.  */
41      char data[1];
42
43      /* Because we want any type of data to be well aligned after the ID,
44	 the following elements are here.  They are never accessed so
45	 the allocated object may be even smaller than this structure.  */
46      char *align_p;
47      HOST_WIDEST_INT align_i;
48      long double align_ld;
49    } u;
50} allocation_object;
51
52/* Convert a pointer to allocation_object from a pointer to user data.  */
53#define ALLOCATION_OBJECT_PTR_FROM_USER_PTR(X)				\
54   ((allocation_object *) (((char *) (X))				\
55			   - offsetof (allocation_object, u.data)))
56
57/* Convert a pointer to user data from a pointer to allocation_object.  */
58#define USER_PTR_FROM_ALLOCATION_OBJECT_PTR(X)				\
59   ((void *) (((allocation_object *) (X))->u.data))
60
61#ifdef ENABLE_CHECKING
62/* Last used ID.  */
63static ALLOC_POOL_ID_TYPE last_id;
64#endif
65
66#ifdef GATHER_STATISTICS
67
68/* Store information about each particular alloc_pool.  */
69struct alloc_pool_descriptor
70{
71  const char *name;
72  int allocated;
73  int created;
74  int peak;
75  int current;
76};
77
78/* Hashtable mapping alloc_pool names to descriptors.  */
79static htab_t alloc_pool_hash;
80
81/* Hashtable helpers.  */
82static hashval_t
83hash_descriptor (const void *p)
84{
85  const struct alloc_pool_descriptor *d = p;
86  return htab_hash_pointer (d->name);
87}
88static int
89eq_descriptor (const void *p1, const void *p2)
90{
91  const struct alloc_pool_descriptor *d = p1;
92  return d->name == p2;
93}
94
95/* For given name, return descriptor, create new if needed.  */
96static struct alloc_pool_descriptor *
97alloc_pool_descriptor (const char *name)
98{
99  struct alloc_pool_descriptor **slot;
100
101  if (!alloc_pool_hash)
102    alloc_pool_hash = htab_create (10, hash_descriptor, eq_descriptor, NULL);
103
104  slot = (struct alloc_pool_descriptor **)
105    htab_find_slot_with_hash (alloc_pool_hash, name,
106			      htab_hash_pointer (name),
107			      1);
108  if (*slot)
109    return *slot;
110  *slot = xcalloc (sizeof (**slot), 1);
111  (*slot)->name = name;
112  return *slot;
113}
114#endif
115
116/* Create a pool of things of size SIZE, with NUM in each block we
117   allocate.  */
118
119alloc_pool
120create_alloc_pool (const char *name, size_t size, size_t num)
121{
122  alloc_pool pool;
123  size_t pool_size, header_size;
124#ifdef GATHER_STATISTICS
125  struct alloc_pool_descriptor *desc;
126#endif
127
128  gcc_assert (name);
129
130  /* Make size large enough to store the list header.  */
131  if (size < sizeof (alloc_pool_list))
132    size = sizeof (alloc_pool_list);
133
134  /* Now align the size to a multiple of 4.  */
135  size = align_eight (size);
136
137#ifdef ENABLE_CHECKING
138  /* Add the aligned size of ID.  */
139  size += offsetof (allocation_object, u.data);
140#endif
141
142  /* Um, we can't really allocate 0 elements per block.  */
143  gcc_assert (num);
144
145  /* Find the size of the pool structure, and the name.  */
146  pool_size = sizeof (struct alloc_pool_def);
147
148  /* and allocate that much memory.  */
149  pool = xmalloc (pool_size);
150
151  /* Now init the various pieces of our pool structure.  */
152  pool->name = /*xstrdup (name)*/name;
153#ifdef GATHER_STATISTICS
154  desc = alloc_pool_descriptor (name);
155  desc->created++;
156#endif
157  pool->elt_size = size;
158  pool->elts_per_block = num;
159
160  /* List header size should be a multiple of 8.  */
161  header_size = align_eight (sizeof (struct alloc_pool_list_def));
162
163  pool->block_size = (size * num) + header_size;
164  pool->free_list = NULL;
165  pool->elts_allocated = 0;
166  pool->elts_free = 0;
167  pool->blocks_allocated = 0;
168  pool->block_list = NULL;
169
170#ifdef ENABLE_CHECKING
171  /* Increase the last used ID and use it for this pool.
172     ID == 0 is used for free elements of pool so skip it.  */
173  last_id++;
174  if (last_id == 0)
175    last_id++;
176
177  pool->id = last_id;
178#endif
179
180  return (pool);
181}
182
183/* Free all memory allocated for the given memory pool.  */
184void
185free_alloc_pool (alloc_pool pool)
186{
187  alloc_pool_list block, next_block;
188#ifdef GATHER_STATISTICS
189  struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
190#endif
191
192  gcc_assert (pool);
193
194  /* Free each block allocated to the pool.  */
195  for (block = pool->block_list; block != NULL; block = next_block)
196    {
197      next_block = block->next;
198      free (block);
199#ifdef GATHER_STATISTICS
200      desc->current -= pool->block_size;
201#endif
202    }
203#ifdef ENABLE_CHECKING
204  memset (pool, 0xaf, sizeof (*pool));
205#endif
206  /* Lastly, free the pool.  */
207  free (pool);
208}
209
210/* Frees the alloc_pool, if it is empty and zero *POOL in this case.  */
211void
212free_alloc_pool_if_empty (alloc_pool *pool)
213{
214  if ((*pool)->elts_free == (*pool)->elts_allocated)
215    {
216      free_alloc_pool (*pool);
217      *pool = NULL;
218    }
219}
220
221/* Allocates one element from the pool specified.  */
222void *
223pool_alloc (alloc_pool pool)
224{
225  alloc_pool_list header;
226  char *block;
227#ifdef GATHER_STATISTICS
228  struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
229
230  desc->allocated+=pool->elt_size;
231#endif
232
233  gcc_assert (pool);
234
235  /* If there are no more free elements, make some more!.  */
236  if (!pool->free_list)
237    {
238      size_t i;
239      alloc_pool_list block_header;
240
241      /* Make the block.  */
242      block = XNEWVEC (char, pool->block_size);
243      block_header = (alloc_pool_list) block;
244      block += align_eight (sizeof (struct alloc_pool_list_def));
245#ifdef GATHER_STATISTICS
246      desc->current += pool->block_size;
247      if (desc->peak < desc->current)
248	desc->peak = desc->current;
249#endif
250
251      /* Throw it on the block list.  */
252      block_header->next = pool->block_list;
253      pool->block_list = block_header;
254
255      /* Now put the actual block pieces onto the free list.  */
256      for (i = 0; i < pool->elts_per_block; i++, block += pool->elt_size)
257      {
258#ifdef ENABLE_CHECKING
259	/* Mark the element to be free.  */
260	((allocation_object *) block)->id = 0;
261#endif
262	header = (alloc_pool_list) USER_PTR_FROM_ALLOCATION_OBJECT_PTR (block);
263	header->next = pool->free_list;
264	pool->free_list = header;
265      }
266      /* Also update the number of elements we have free/allocated, and
267	 increment the allocated block count.  */
268      pool->elts_allocated += pool->elts_per_block;
269      pool->elts_free += pool->elts_per_block;
270      pool->blocks_allocated += 1;
271    }
272
273  /* Pull the first free element from the free list, and return it.  */
274  header = pool->free_list;
275  pool->free_list = header->next;
276  pool->elts_free--;
277
278#ifdef ENABLE_CHECKING
279  /* Set the ID for element.  */
280  ALLOCATION_OBJECT_PTR_FROM_USER_PTR (header)->id = pool->id;
281#endif
282
283  return ((void *) header);
284}
285
286/* Puts PTR back on POOL's free list.  */
287void
288pool_free (alloc_pool pool, void *ptr)
289{
290  alloc_pool_list header;
291
292  gcc_assert (ptr);
293
294#ifdef ENABLE_CHECKING
295  memset (ptr, 0xaf, pool->elt_size - offsetof (allocation_object, u.data));
296
297  /* Check whether the PTR was allocated from POOL.  */
298  gcc_assert (pool->id == ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id);
299
300  /* Mark the element to be free.  */
301  ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id = 0;
302#else
303  /* Check if we free more than we allocated, which is Bad (TM).  */
304  gcc_assert (pool->elts_free < pool->elts_allocated);
305#endif
306
307  header = (alloc_pool_list) ptr;
308  header->next = pool->free_list;
309  pool->free_list = header;
310  pool->elts_free++;
311}
312/* Output per-alloc_pool statistics.  */
313#ifdef GATHER_STATISTICS
314
315/* Used to accumulate statistics about alloc_pool sizes.  */
316struct output_info
317{
318  int count;
319  int size;
320};
321
322/* Called via htab_traverse.  Output alloc_pool descriptor pointed out by SLOT
323   and update statistics.  */
324static int
325print_statistics (void **slot, void *b)
326{
327  struct alloc_pool_descriptor *d = (struct alloc_pool_descriptor *) *slot;
328  struct output_info *i = (struct output_info *) b;
329
330  if (d->allocated)
331    {
332      fprintf (stderr, "%-21s %6d %10d %10d %10d\n", d->name,
333	       d->created, d->allocated, d->peak, d->current);
334      i->size += d->allocated;
335      i->count += d->created;
336    }
337  return 1;
338}
339#endif
340
341/* Output per-alloc_pool memory usage statistics.  */
342void
343dump_alloc_pool_statistics (void)
344{
345#ifdef GATHER_STATISTICS
346  struct output_info info;
347
348  if (!alloc_pool_hash)
349    return;
350
351  fprintf (stderr, "\nAlloc-pool Kind        Pools  Allocated      Peak        Leak\n");
352  fprintf (stderr, "-------------------------------------------------------------\n");
353  info.count = 0;
354  info.size = 0;
355  htab_traverse (alloc_pool_hash, print_statistics, &info);
356  fprintf (stderr, "-------------------------------------------------------------\n");
357  fprintf (stderr, "%-20s %7d %10d\n",
358	   "Total", info.count, info.size);
359  fprintf (stderr, "-------------------------------------------------------------\n");
360#endif
361}
362