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authorStan Shebs <shebs@codesourcery.com>1999-04-16 01:35:26 +0000
committerStan Shebs <shebs@codesourcery.com>1999-04-16 01:35:26 +0000
commitc906108c21474dfb4ed285bcc0ac6fe02cd400cc (patch)
treea0015aa5cedc19ccbab307251353a41722a3ae13 /gdb/bcache.c
parentcd946cff9ede3f30935803403f06f6ed30cad136 (diff)
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Initial creation of sourceware repositorygdb-4_18-branchpoint
Diffstat (limited to 'gdb/bcache.c')
-rw-r--r--gdb/bcache.c219
1 files changed, 219 insertions, 0 deletions
diff --git a/gdb/bcache.c b/gdb/bcache.c
new file mode 100644
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--- /dev/null
+++ b/gdb/bcache.c
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+/* Implement a cached obstack.
+ Written by Fred Fish (fnf@cygnus.com)
+ Copyright 1995, 1998 Free Software Foundation, Inc.
+
+This file is part of GDB.
+
+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 of the License, 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, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+#include "defs.h"
+#include "obstack.h"
+#include "bcache.h"
+#include "gdb_string.h" /* For memcpy declaration */
+
+/* Prototypes for local functions. */
+
+static unsigned int hash PARAMS ((void *, int));
+
+static void *lookup_cache PARAMS ((void *, int, int, struct bcache *));
+
+/* FIXME: Incredibly simplistic hash generator. Probably way too expensive
+ (consider long strings) and unlikely to have good distribution across hash
+ values for typical input. */
+
+static unsigned int
+hash (bytes, count)
+ void *bytes;
+ int count;
+{
+ unsigned int len;
+ unsigned long hashval;
+ unsigned int c;
+ const unsigned char *data = bytes;
+
+ hashval = 0;
+ len = 0;
+ while (count-- > 0)
+ {
+ c = *data++;
+ hashval += c + (c << 17);
+ hashval ^= hashval >> 2;
+ ++len;
+ }
+ hashval += len + (len << 17);
+ hashval ^= hashval >> 2;
+ return (hashval % BCACHE_HASHSIZE);
+}
+
+static void *
+lookup_cache (bytes, count, hashval, bcachep)
+ void *bytes;
+ int count;
+ int hashval;
+ struct bcache *bcachep;
+{
+ void *location = NULL;
+ struct hashlink **hashtablep;
+ struct hashlink *linkp;
+
+ hashtablep = bcachep -> indextable[count];
+ if (hashtablep != NULL)
+ {
+ linkp = hashtablep[hashval];
+ while (linkp != NULL)
+ {
+ if (memcmp (BCACHE_DATA (linkp), bytes, count) == 0)
+ {
+ location = BCACHE_DATA (linkp);
+ break;
+ }
+ linkp = linkp -> next;
+ }
+ }
+ return (location);
+}
+
+void *
+bcache (bytes, count, bcachep)
+ void *bytes;
+ int count;
+ struct bcache *bcachep;
+{
+ int hashval;
+ void *location;
+ struct hashlink *newlink;
+ struct hashlink **linkpp;
+ struct hashlink ***hashtablepp;
+
+ if (count >= BCACHE_MAXLENGTH)
+ {
+ /* Rare enough to just stash unique copies */
+ location = (void *) obstack_alloc (&bcachep->cache, count);
+ bcachep -> cache_bytes += count;
+ memcpy (location, bytes, count);
+ bcachep -> bcache_overflows++;
+ }
+ else
+ {
+ hashval = hash (bytes, count);
+ location = lookup_cache (bytes, count, hashval, bcachep);
+ if (location != NULL)
+ {
+ bcachep -> cache_savings += count;
+ bcachep -> cache_hits++;
+ }
+ else
+ {
+ bcachep -> cache_misses++;
+ hashtablepp = &bcachep -> indextable[count];
+ if (*hashtablepp == NULL)
+ {
+ *hashtablepp = (struct hashlink **)
+ obstack_alloc (&bcachep->cache, BCACHE_HASHSIZE * sizeof (struct hashlink *));
+ bcachep -> cache_bytes += BCACHE_HASHSIZE * sizeof (struct hashlink *);
+ memset (*hashtablepp, 0, BCACHE_HASHSIZE * sizeof (struct hashlink *));
+ }
+ linkpp = &(*hashtablepp)[hashval];
+ newlink = (struct hashlink *)
+ obstack_alloc (&bcachep->cache, BCACHE_DATA_ALIGNMENT + count);
+ bcachep -> cache_bytes += BCACHE_DATA_ALIGNMENT + count;
+ memcpy (BCACHE_DATA (newlink), bytes, count);
+ newlink -> next = *linkpp;
+ *linkpp = newlink;
+ location = BCACHE_DATA (newlink);
+ }
+ }
+ return (location);
+}
+
+#if MAINTENANCE_CMDS
+
+void
+print_bcache_statistics (bcachep, id)
+ struct bcache *bcachep;
+ char *id;
+{
+ struct hashlink **hashtablep;
+ struct hashlink *linkp;
+ int tidx, tcount, hidx, hcount, lcount, lmax, temp, lmaxt, lmaxh;
+
+ for (lmax = lcount = tcount = hcount = tidx = 0; tidx < BCACHE_MAXLENGTH; tidx++)
+ {
+ hashtablep = bcachep -> indextable[tidx];
+ if (hashtablep != NULL)
+ {
+ tcount++;
+ for (hidx = 0; hidx < BCACHE_HASHSIZE; hidx++)
+ {
+ linkp = hashtablep[hidx];
+ if (linkp != NULL)
+ {
+ hcount++;
+ for (temp = 0; linkp != NULL; linkp = linkp -> next)
+ {
+ lcount++;
+ temp++;
+ }
+ if (temp > lmax)
+ {
+ lmax = temp;
+ lmaxt = tidx;
+ lmaxh = hidx;
+ }
+ }
+ }
+ }
+ }
+ printf_filtered (" Cached '%s' statistics:\n", id);
+ printf_filtered (" Cache hits: %d\n", bcachep -> cache_hits);
+ printf_filtered (" Cache misses: %d\n", bcachep -> cache_misses);
+ printf_filtered (" Cache hit ratio: ");
+ if (bcachep -> cache_hits + bcachep -> cache_misses > 0)
+ {
+ printf_filtered ("%d%%\n", ((bcachep -> cache_hits) * 100) /
+ (bcachep -> cache_hits + bcachep -> cache_misses));
+ }
+ else
+ {
+ printf_filtered ("(not applicable)\n");
+ }
+ printf_filtered (" Space used for caching: %d\n", bcachep -> cache_bytes);
+ printf_filtered (" Space saved by cache hits: %d\n", bcachep -> cache_savings);
+ printf_filtered (" Number of bcache overflows: %d\n", bcachep -> bcache_overflows);
+ printf_filtered (" Number of index buckets used: %d\n", tcount);
+ printf_filtered (" Number of hash table buckets used: %d\n", hcount);
+ printf_filtered (" Number of chained items: %d\n", lcount);
+ printf_filtered (" Average hash table population: ");
+ if (tcount > 0)
+ {
+ printf_filtered ("%d%%\n", (hcount * 100) / (tcount * BCACHE_HASHSIZE));
+ }
+ else
+ {
+ printf_filtered ("(not applicable)\n");
+ }
+ printf_filtered (" Average chain length ");
+ if (hcount > 0)
+ {
+ printf_filtered ("%d\n", lcount / hcount);
+ }
+ else
+ {
+ printf_filtered ("(not applicable)\n");
+ }
+ printf_filtered (" Maximum chain length %d at %d:%d\n", lmax, lmaxt, lmaxh);
+}
+
+#endif /* MAINTENANCE_CMDS */