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authorobrien <obrien@FreeBSD.org>2002-02-01 18:16:02 +0000
committerobrien <obrien@FreeBSD.org>2002-02-01 18:16:02 +0000
commitc9ab9ae440a8066b2c2b85b157b1fdadcf09916a (patch)
tree086d9d6c8fbd4fc8fe4495059332f66bc0f8d12b /contrib/gcc/hashtable.c
parent2ecfd8bd04b63f335c1ec6295740a4bfd97a4fa6 (diff)
downloadFreeBSD-src-c9ab9ae440a8066b2c2b85b157b1fdadcf09916a.zip
FreeBSD-src-c9ab9ae440a8066b2c2b85b157b1fdadcf09916a.tar.gz
Enlist the FreeBSD-CURRENT users as testers of what is to become Gcc 3.1.0.
These bits are taken from the FSF anoncvs repo on 1-Feb-2002 08:20 PST.
Diffstat (limited to 'contrib/gcc/hashtable.c')
-rw-r--r--contrib/gcc/hashtable.c326
1 files changed, 326 insertions, 0 deletions
diff --git a/contrib/gcc/hashtable.c b/contrib/gcc/hashtable.c
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+/* Hash tables.
+ Copyright (C) 2000, 2001 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
+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; if not, write to the Free Software
+Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+ 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 "hashtable.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. Also, the ability to
+ delete members from the table has been removed. */
+
+static unsigned int calc_hash PARAMS ((const unsigned char *, unsigned int));
+static void ht_expand PARAMS ((hash_table *));
+
+/* Let particular systems override the size of a chunk. */
+#ifndef OBSTACK_CHUNK_SIZE
+#define OBSTACK_CHUNK_SIZE 0
+#endif
+ /* Let them override the alloc and free routines too. */
+#ifndef OBSTACK_CHUNK_ALLOC
+#define OBSTACK_CHUNK_ALLOC xmalloc
+#endif
+#ifndef OBSTACK_CHUNK_FREE
+#define OBSTACK_CHUNK_FREE free
+#endif
+
+/* Initialise an obstack. */
+void
+gcc_obstack_init (obstack)
+ struct obstack *obstack;
+{
+ _obstack_begin (obstack, OBSTACK_CHUNK_SIZE, 0,
+ (void *(*) PARAMS ((long))) OBSTACK_CHUNK_ALLOC,
+ (void (*) PARAMS ((void *))) OBSTACK_CHUNK_FREE);
+}
+
+/* Calculate the hash of the string STR of length LEN. */
+
+static unsigned int
+calc_hash (str, len)
+ const unsigned char *str;
+ unsigned int len;
+{
+ unsigned int n = len;
+ unsigned int r = 0;
+#define HASHSTEP(r, c) ((r) * 67 + ((c) - 113));
+
+ while (n--)
+ r = HASHSTEP (r, *str++);
+
+ return r + len;
+#undef HASHSTEP
+}
+
+/* Initialize an identifier hashtable. */
+
+hash_table *
+ht_create (order)
+ unsigned int order;
+{
+ unsigned int nslots = 1 << order;
+ hash_table *table;
+
+ table = (hash_table *) xmalloc (sizeof (hash_table));
+ memset (table, 0, sizeof (hash_table));
+
+ /* Strings need no alignment. */
+ gcc_obstack_init (&table->stack);
+ obstack_alignment_mask (&table->stack) = 0;
+
+ table->entries = (hashnode *) xcalloc (nslots, sizeof (hashnode));
+ table->nslots = nslots;
+ return table;
+}
+
+/* Frees all memory associated with a hash table. */
+
+void
+ht_destroy (table)
+ hash_table *table;
+{
+ obstack_free (&table->stack, NULL);
+ 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, and, if
+ INSERT is CPP_ALLOCED, frees the last obstack object. 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. */
+hashnode
+ht_lookup (table, str, len, insert)
+ hash_table *table;
+ const unsigned char *str;
+ unsigned int len;
+ enum ht_lookup_option insert;
+{
+ unsigned int hash = calc_hash (str, len);
+ unsigned int hash2;
+ unsigned int index;
+ size_t sizemask;
+ hashnode node;
+
+ sizemask = table->nslots - 1;
+ index = hash & sizemask;
+
+ /* hash2 must be odd, so we're guaranteed to visit every possible
+ location in the table during rehashing. */
+ hash2 = ((hash * 17) & sizemask) | 1;
+ table->searches++;
+
+ for (;;)
+ {
+ node = table->entries[index];
+
+ if (node == NULL)
+ break;
+
+ if (HT_LEN (node) == 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, (PTR) str);
+ return node;
+ }
+
+ index = (index + hash2) & sizemask;
+ table->collisions++;
+ }
+
+ if (insert == HT_NO_INSERT)
+ return NULL;
+
+ node = (*table->alloc_node) (table);
+ table->entries[index] = node;
+
+ HT_LEN (node) = len;
+ if (insert == HT_ALLOC)
+ HT_STR (node) = obstack_copy0 (&table->stack, str, len);
+ else
+ HT_STR (node) = str;
+
+ 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 (table)
+ hash_table *table;
+{
+ hashnode *nentries, *p, *limit;
+ unsigned int size, sizemask;
+
+ size = table->nslots * 2;
+ nentries = (hashnode *) xcalloc (size, sizeof (hashnode));
+ sizemask = size - 1;
+
+ p = table->entries;
+ limit = p + table->nslots;
+ do
+ if (*p)
+ {
+ unsigned int index, hash, hash2;
+
+ hash = calc_hash (HT_STR (*p), HT_LEN (*p));
+ hash2 = ((hash * 17) & sizemask) | 1;
+ index = hash & sizemask;
+
+ for (;;)
+ {
+ if (! nentries[index])
+ {
+ nentries[index] = *p;
+ break;
+ }
+
+ index = (index + hash2) & sizemask;
+ }
+ }
+ while (++p < limit);
+
+ free (table->entries);
+ table->entries = nentries;
+ table->nslots = size;
+}
+
+/* For all nodes in TABLE, callback CB with parameters TABLE->PFILE,
+ the node, and V. */
+void
+ht_forall (table, cb, v)
+ hash_table *table;
+ ht_cb cb;
+ const PTR v;
+{
+ hashnode *p, *limit;
+
+ p = table->entries;
+ limit = p + table->nslots;
+ do
+ if (*p)
+ {
+ if ((*cb) (table->pfile, *p, v) == 0)
+ break;
+ }
+ while (++p < limit);
+}
+
+/* Dump allocation statistics to stderr. */
+
+void
+ht_dump_statistics (table)
+ hash_table *table;
+{
+ size_t nelts, nids, overhead, headers;
+ size_t total_bytes, longest, sum_of_squares;
+ double 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)
+ {
+ size_t n = HT_LEN (*p);
+
+ total_bytes += n;
+ sum_of_squares += 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, "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. */
+double
+approx_sqrt (x)
+ 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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