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-rw-r--r--libcpp/symtab.c363
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diff --git a/libcpp/symtab.c b/libcpp/symtab.c
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+/* Hash tables.
+ 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 3, or (at your option) any
+later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+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
+ what you give them. Help stamp out software-hoarding! */
+
+#include "config.h"
+#include "system.h"
+#include "symtab.h"
+
+/* The code below is a specialization of Vladimir Makarov's expandable
+ 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. */
+
+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
+calc_hash (const unsigned char *str, size_t len)
+{
+ size_t n = len;
+ unsigned int r = 0;
+
+ while (n--)
+ r = HT_HASHSTEP (r, *str++);
+
+ return HT_HASHFINISH (r, len);
+}
+
+/* Initialize an identifier hashtable. */
+
+hash_table *
+ht_create (unsigned int order)
+{
+ unsigned int nslots = 1 << order;
+ hash_table *table;
+
+ table = XCNEW (hash_table);
+
+ /* Strings need no alignment. */
+ _obstack_begin (&table->stack, 0, 0,
+ (void *(*) (long)) xmalloc,
+ (void (*) (void *)) free);
+
+ obstack_alignment_mask (&table->stack) = 0;
+
+ table->entries = XCNEWVEC (hashnode, nslots);
+ table->entries_owned = true;
+ table->nslots = nslots;
+ return table;
+}
+
+/* Frees all memory associated with a hash table. */
+
+void
+ht_destroy (hash_table *table)
+{
+ obstack_free (&table->stack, NULL);
+ if (table->entries_owned)
+ free (table->entries);
+ free (table);
+}
+
+/* Returns the hash entry for the a STR of length LEN. If that string
+ 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 allocated. */
+hashnode
+ht_lookup (hash_table *table, const unsigned char *str, size_t len,
+ enum ht_lookup_option insert)
+{
+ return ht_lookup_with_hash (table, str, len, calc_hash (str, len),
+ insert);
+}
+
+hashnode
+ht_lookup_with_hash (hash_table *table, const unsigned char *str,
+ 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;
+
+ sizemask = table->nslots - 1;
+ index = hash & sizemask;
+ table->searches++;
+
+ node = table->entries[index];
+
+ if (node != NULL)
+ {
+ 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. */
+ hash2 = ((hash * 17) & sizemask) | 1;
+
+ for (;;)
+ {
+ 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 (table->alloc_subobject)
+ {
+ char *chars = (char *) 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);
+
+ if (++table->nelements * 4 >= table->nslots * 3)
+ /* Must expand the string table. */
+ ht_expand (table);
+
+ return node;
+}
+
+/* Double the size of a hash table, re-hashing existing entries. */
+
+static void
+ht_expand (hash_table *table)
+{
+ hashnode *nentries, *p, *limit;
+ unsigned int size, sizemask;
+
+ size = table->nslots * 2;
+ nentries = XCNEWVEC (hashnode, size);
+ sizemask = size - 1;
+
+ p = table->entries;
+ limit = p + table->nslots;
+ do
+ 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;
+ }
+ while (++p < limit);
+
+ if (table->entries_owned)
+ free (table->entries);
+ table->entries_owned = true;
+ table->entries = nentries;
+ table->nslots = size;
+}
+
+/* For all nodes in TABLE, callback CB with parameters TABLE->PFILE,
+ the node, and V. */
+void
+ht_forall (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;
+ }
+ 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))
+ *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)
+{
+ if (ht->entries_owned)
+ free (ht->entries);
+ ht->entries = entries;
+ ht->nslots = nslots;
+ ht->nelements = nelements;
+ ht->entries_owned = own;
+}
+
+/* Dump allocation statistics to stderr. */
+
+void
+ht_dump_statistics (hash_table *table)
+{
+ size_t nelts, nids, overhead, headers;
+ 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))))
+#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 == DELETED)
+ ++deleted;
+ else if (*p)
+ {
+ size_t n = HT_LEN (*p);
+
+ total_bytes += n;
+ sum_of_squares += (double) n * n;
+ if (n > longest)
+ longest = n;
+ nids++;
+ }
+ while (++p < limit);
+
+ nelts = table->nelements;
+ overhead = obstack_memory_used (&table->stack) - total_bytes;
+ headers = table->nslots * sizeof (hashnode);
+
+ fprintf (stderr, "\nString pool\nentries\t\t%lu\n",
+ (unsigned long) nelts);
+ fprintf (stderr, "identifiers\t%lu (%.2f%%)\n",
+ (unsigned long) nids, nids * 100.0 / nelts);
+ fprintf (stderr, "slots\t\t%lu\n",
+ (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));
+ fprintf (stderr, "table size\t%lu%c\n",
+ 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);
+ fprintf (stderr, "ins/search\t%.4f\n",
+ (double) nelts / (double) table->searches);
+ fprintf (stderr, "avg. entry\t%.2f bytes (+/- %.2f)\n",
+ exp_len, approx_sqrt (exp_len2 - exp2_len));
+ fprintf (stderr, "longest entry\t%lu\n",
+ (unsigned long) longest);
+#undef SCALE
+#undef LABEL
+}
+
+/* Return the approximate positive square root of a number N. This is for
+ statistical reports, not code generation. */
+static double
+approx_sqrt (double x)
+{
+ double s, d;
+
+ if (x < 0)
+ abort ();
+ if (x == 0)
+ return 0;
+
+ s = x;
+ do
+ {
+ d = (s * s - x) / (2 * s);
+ s -= d;
+ }
+ while (d > .0001);
+ return s;
+}
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