+/* A frame stash used to speed up frame lookups. Create a hash table
+ to stash frames previously accessed from the frame cache for
+ quicker subsequent retrieval. The hash table is emptied whenever
+ the frame cache is invalidated. */
+
+static htab_t frame_stash;
+
+/* Internal function to calculate a hash from the frame_id addresses,
+ using as many valid addresses as possible. Frames below level 0
+ are not stored in the hash table. */
+
+static hashval_t
+frame_addr_hash (const void *ap)
+{
+ const struct frame_info *frame = ap;
+ const struct frame_id f_id = frame->this_id.value;
+ hashval_t hash = 0;
+
+ gdb_assert (f_id.stack_status != FID_STACK_INVALID
+ || f_id.code_addr_p
+ || f_id.special_addr_p);
+
+ if (f_id.stack_status == FID_STACK_VALID)
+ hash = iterative_hash (&f_id.stack_addr,
+ sizeof (f_id.stack_addr), hash);
+ if (f_id.code_addr_p)
+ hash = iterative_hash (&f_id.code_addr,
+ sizeof (f_id.code_addr), hash);
+ if (f_id.special_addr_p)
+ hash = iterative_hash (&f_id.special_addr,
+ sizeof (f_id.special_addr), hash);
+
+ return hash;
+}
+
+/* Internal equality function for the hash table. This function
+ defers equality operations to frame_id_eq. */
+
+static int
+frame_addr_hash_eq (const void *a, const void *b)
+{
+ const struct frame_info *f_entry = a;
+ const struct frame_info *f_element = b;
+
+ return frame_id_eq (f_entry->this_id.value,
+ f_element->this_id.value);
+}
+
+/* Internal function to create the frame_stash hash table. 100 seems
+ to be a good compromise to start the hash table at. */
+
+static void
+frame_stash_create (void)
+{
+ frame_stash = htab_create (100,
+ frame_addr_hash,
+ frame_addr_hash_eq,
+ NULL);
+}
+
+/* Internal function to add a frame to the frame_stash hash table.
+ Returns false if a frame with the same ID was already stashed, true
+ otherwise. */
+
+static int
+frame_stash_add (struct frame_info *frame)
+{
+ struct frame_info **slot;
+
+ /* Do not try to stash the sentinel frame. */
+ gdb_assert (frame->level >= 0);
+
+ slot = (struct frame_info **) htab_find_slot (frame_stash,
+ frame,
+ INSERT);
+
+ /* If we already have a frame in the stack with the same id, we
+ either have a stack cycle (corrupted stack?), or some bug
+ elsewhere in GDB. In any case, ignore the duplicate and return
+ an indication to the caller. */
+ if (*slot != NULL)
+ return 0;
+
+ *slot = frame;
+ return 1;
+}
+
+/* Internal function to search the frame stash for an entry with the
+ given frame ID. If found, return that frame. Otherwise return
+ NULL. */
+
+static struct frame_info *
+frame_stash_find (struct frame_id id)
+{
+ struct frame_info dummy;
+ struct frame_info *frame;
+
+ dummy.this_id.value = id;
+ frame = htab_find (frame_stash, &dummy);
+ return frame;
+}
+
+/* Internal function to invalidate the frame stash by removing all
+ entries in it. This only occurs when the frame cache is
+ invalidated. */
+
+static void
+frame_stash_invalidate (void)
+{
+ htab_empty (frame_stash);
+}
+