/* Hash tables.
- Copyright (C) 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2003, 2004, 2008, 2009
+ Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
-Free Software Foundation; either version 2, or (at your option) any
+Free Software Foundation; either version 3, or (at your option) any
later version.
This program is distributed in the hope that it will be useful,
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
-along with this program; if not, write to the Free Software
-Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+along with this program; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>.
In other words, you are welcome to use, share and improve this program.
You are forbidden to forbid anyone else to use, share and improve
hash tables (see libiberty/hashtab.c). The abstraction penalty was
too high to continue using the generic form. This code knows
intrinsically how to calculate a hash value, and how to compare an
- existing entry with a potential new one. Also, the ability to
- delete members from the table has been removed. */
+ existing entry with a potential new one. */
static unsigned int calc_hash (const unsigned char *, size_t);
static void ht_expand (hash_table *);
static double approx_sqrt (double);
+/* A deleted entry. */
+#define DELETED ((hashnode) -1)
+
/* Calculate the hash of the string STR of length LEN. */
static unsigned int
/* Strings need no alignment. */
_obstack_begin (&table->stack, 0, 0,
- (void *(*) (long)) xmalloc,
- (void (*) (void *)) free);
+ (void *(*) (long)) xmalloc,
+ (void (*) (void *)) free);
obstack_alignment_mask (&table->stack) = 0;
}
/* Returns the hash entry for the a STR of length LEN. If that string
- already exists in the table, returns the existing entry, and, if
- INSERT is CPP_ALLOCED, frees the last obstack object. If the
+ already exists in the table, returns the existing entry. If the
identifier hasn't been seen before, and INSERT is CPP_NO_INSERT,
returns NULL. Otherwise insert and returns a new entry. A new
- string is alloced if INSERT is CPP_ALLOC, otherwise INSERT is
- CPP_ALLOCED and the item is assumed to be at the top of the
- obstack. */
+ string is allocated. */
hashnode
ht_lookup (hash_table *table, const unsigned char *str, size_t len,
- enum ht_lookup_option insert)
+ enum ht_lookup_option insert)
{
return ht_lookup_with_hash (table, str, len, calc_hash (str, len),
- insert);
+ insert);
}
hashnode
ht_lookup_with_hash (hash_table *table, const unsigned char *str,
- size_t len, unsigned int hash,
- enum ht_lookup_option insert)
+ size_t len, unsigned int hash,
+ enum ht_lookup_option insert)
{
unsigned int hash2;
unsigned int index;
+ unsigned int deleted_index = table->nslots;
size_t sizemask;
hashnode node;
table->searches++;
node = table->entries[index];
-
+
if (node != NULL)
{
- if (node->hash_value == hash
- && HT_LEN (node) == (unsigned int) len
- && !memcmp (HT_STR (node), str, len))
- {
- if (insert == HT_ALLOCED)
- /* The string we search for was placed at the end of the
- obstack. Release it. */
- obstack_free (&table->stack, (void *) str);
- return node;
- }
+ if (node == DELETED)
+ deleted_index = index;
+ else if (node->hash_value == hash
+ && HT_LEN (node) == (unsigned int) len
+ && !memcmp (HT_STR (node), str, len))
+ return node;
/* hash2 must be odd, so we're guaranteed to visit every possible
- location in the table during rehashing. */
+ location in the table during rehashing. */
hash2 = ((hash * 17) & sizemask) | 1;
for (;;)
- {
- table->collisions++;
- index = (index + hash2) & sizemask;
- node = table->entries[index];
- if (node == NULL)
- break;
-
- if (node->hash_value == hash
- && HT_LEN (node) == (unsigned int) len
- && !memcmp (HT_STR (node), str, len))
- {
- if (insert == HT_ALLOCED)
- /* The string we search for was placed at the end of the
- obstack. Release it. */
- obstack_free (&table->stack, (void *) str);
- return node;
- }
- }
+ {
+ table->collisions++;
+ index = (index + hash2) & sizemask;
+ node = table->entries[index];
+ if (node == NULL)
+ break;
+
+ if (node == DELETED)
+ {
+ if (deleted_index != table->nslots)
+ deleted_index = index;
+ }
+ else if (node->hash_value == hash
+ && HT_LEN (node) == (unsigned int) len
+ && !memcmp (HT_STR (node), str, len))
+ return node;
+ }
}
if (insert == HT_NO_INSERT)
return NULL;
+ /* We prefer to overwrite the first deleted slot we saw. */
+ if (deleted_index != table->nslots)
+ index = deleted_index;
+
node = (*table->alloc_node) (table);
table->entries[index] = node;
HT_LEN (node) = (unsigned int) len;
node->hash_value = hash;
- if (insert == HT_ALLOC)
+
+ if (table->alloc_subobject)
+ {
+ char *chars = table->alloc_subobject (len + 1);
+ memcpy (chars, str, len);
+ chars[len] = '\0';
+ HT_STR (node) = (const unsigned char *) chars;
+ }
+ else
HT_STR (node) = (const unsigned char *) obstack_copy0 (&table->stack,
str, len);
- else
- HT_STR (node) = str;
if (++table->nelements * 4 >= table->nslots * 3)
/* Must expand the string table. */
p = table->entries;
limit = p + table->nslots;
do
- if (*p)
+ if (*p && *p != DELETED)
{
- unsigned int index, hash, hash2;
-
- hash = (*p)->hash_value;
- index = hash & sizemask;
-
- if (nentries[index])
- {
- hash2 = ((hash * 17) & sizemask) | 1;
- do
- {
- index = (index + hash2) & sizemask;
- }
- while (nentries[index]);
- }
- nentries[index] = *p;
+ unsigned int index, hash, hash2;
+
+ hash = (*p)->hash_value;
+ index = hash & sizemask;
+
+ if (nentries[index])
+ {
+ hash2 = ((hash * 17) & sizemask) | 1;
+ do
+ {
+ index = (index + hash2) & sizemask;
+ }
+ while (nentries[index]);
+ }
+ nentries[index] = *p;
}
while (++p < limit);
p = table->entries;
limit = p + table->nslots;
do
- if (*p)
+ if (*p && *p != DELETED)
+ {
+ if ((*cb) (table->pfile, *p, v) == 0)
+ break;
+ }
+ while (++p < limit);
+}
+
+/* Like ht_forall, but a nonzero return from the callback means that
+ the entry should be removed from the table. */
+void
+ht_purge (hash_table *table, ht_cb cb, const void *v)
+{
+ hashnode *p, *limit;
+
+ p = table->entries;
+ limit = p + table->nslots;
+ do
+ if (*p && *p != DELETED)
{
- if ((*cb) (table->pfile, *p, v) == 0)
- break;
+ if ((*cb) (table->pfile, *p, v))
+ *p = DELETED;
}
while (++p < limit);
}
/* Restore the hash table. */
void
ht_load (hash_table *ht, hashnode *entries,
- unsigned int nslots, unsigned int nelements,
- bool own)
+ unsigned int nslots, unsigned int nelements,
+ bool own)
{
if (ht->entries_owned)
free (ht->entries);
ht_dump_statistics (hash_table *table)
{
size_t nelts, nids, overhead, headers;
- size_t total_bytes, longest;
+ size_t total_bytes, longest, deleted = 0;
double sum_of_squares, exp_len, exp_len2, exp2_len;
hashnode *p, *limit;
#define SCALE(x) ((unsigned long) ((x) < 1024*10 \
- ? (x) \
- : ((x) < 1024*1024*10 \
- ? (x) / 1024 \
- : (x) / (1024*1024))))
+ ? (x) \
+ : ((x) < 1024*1024*10 \
+ ? (x) / 1024 \
+ : (x) / (1024*1024))))
#define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
total_bytes = longest = sum_of_squares = nids = 0;
p = table->entries;
limit = p + table->nslots;
do
- if (*p)
+ if (*p == DELETED)
+ ++deleted;
+ else if (*p)
{
- size_t n = HT_LEN (*p);
+ size_t n = HT_LEN (*p);
- total_bytes += n;
- sum_of_squares += (double) n * n;
- if (n > longest)
- longest = n;
- nids++;
+ total_bytes += n;
+ sum_of_squares += (double) n * n;
+ if (n > longest)
+ longest = n;
+ nids++;
}
while (++p < limit);
headers = table->nslots * sizeof (hashnode);
fprintf (stderr, "\nString pool\nentries\t\t%lu\n",
- (unsigned long) nelts);
+ (unsigned long) nelts);
fprintf (stderr, "identifiers\t%lu (%.2f%%)\n",
- (unsigned long) nids, nids * 100.0 / nelts);
+ (unsigned long) nids, nids * 100.0 / nelts);
fprintf (stderr, "slots\t\t%lu\n",
- (unsigned long) table->nslots);
+ (unsigned long) table->nslots);
+ fprintf (stderr, "deleted\t\t%lu\n",
+ (unsigned long) deleted);
fprintf (stderr, "bytes\t\t%lu%c (%lu%c overhead)\n",
- SCALE (total_bytes), LABEL (total_bytes),
- SCALE (overhead), LABEL (overhead));
+ SCALE (total_bytes), LABEL (total_bytes),
+ SCALE (overhead), LABEL (overhead));
fprintf (stderr, "table size\t%lu%c\n",
- SCALE (headers), LABEL (headers));
+ SCALE (headers), LABEL (headers));
exp_len = (double)total_bytes / (double)nelts;
exp2_len = exp_len * exp_len;
exp_len2 = (double) sum_of_squares / (double) nelts;
fprintf (stderr, "coll/search\t%.4f\n",
- (double) table->collisions / (double) table->searches);
+ (double) table->collisions / (double) table->searches);
fprintf (stderr, "ins/search\t%.4f\n",
- (double) nelts / (double) table->searches);
+ (double) nelts / (double) table->searches);
fprintf (stderr, "avg. entry\t%.2f bytes (+/- %.2f)\n",
- exp_len, approx_sqrt (exp_len2 - exp2_len));
+ exp_len, approx_sqrt (exp_len2 - exp2_len));
fprintf (stderr, "longest entry\t%lu\n",
- (unsigned long) longest);
+ (unsigned long) longest);
#undef SCALE
#undef LABEL
}
projects / fw / sdcc / blobdiff