3 files changed, 70 insertions, 58 deletions

diff --git a/src/fns.c b/src/fns.c
index efec74d4959..74fdf29417e 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -4474,7 +4474,7 @@ hashfn_eql (Lisp_Object key, struct Lisp_Hash_Table *h)
 /* Given H, return a hash code for KEY which uses a user-defined
    function to compare keys.  */
 
-Lisp_Object
+static Lisp_Object
 hashfn_user_defined (Lisp_Object key, struct Lisp_Hash_Table *h)
 {
   Lisp_Object args[] = { h->test.user_hash_function, key };
@@ -4638,11 +4638,10 @@ maybe_resize_hash_table (struct Lisp_Hash_Table *h)
   if (h->next_free < 0)
     {
       ptrdiff_t old_size = HASH_TABLE_SIZE (h);
-      EMACS_INT new_size;
-
-      double float_new_size = old_size * std_rehash_size;
-      if (float_new_size < EMACS_INT_MAX)
-        new_size = float_new_size;
+      /* FIXME: better growth management, ditch std_rehash_size */
+      EMACS_INT new_size = old_size * std_rehash_size;
+      if (new_size < EMACS_INT_MAX)
+        new_size = max (new_size, 32);  /* avoid slow initial growth */
       else
         new_size = EMACS_INT_MAX;
       if (PTRDIFF_MAX < new_size)
@@ -4691,20 +4690,39 @@ maybe_resize_hash_table (struct Lisp_Hash_Table *h)
     }
 }
 
-/* Recompute the hashes (and hence also the "next" pointers).
-   Normally there's never a need to recompute hashes.
-   This is done only on first access to a hash-table loaded from
-   the "pdump", because the objects' addresses may have changed, thus
-   affecting their hashes.  */
+static const struct hash_table_test *
+hash_table_test_from_std (hash_table_std_test_t test)
+{
+  switch (test)
+    {
+    case Test_eq:    return &hashtest_eq;
+    case Test_eql:   return &hashtest_eql;
+    case Test_equal: return &hashtest_equal;
+    }
+  emacs_abort();
+}
+
+/* Rebuild a hash table from its frozen (dumped) form.  */
 void
-hash_table_rehash (Lisp_Object hash)
+hash_table_thaw (Lisp_Object hash_table)
 {
-  struct Lisp_Hash_Table *h = XHASH_TABLE (hash);
-  ptrdiff_t i, count = h->count;
+  struct Lisp_Hash_Table *h = XHASH_TABLE (hash_table);
+
+  /* Freezing discarded most non-essential information; recompute it.
+     The allocation is minimal with no room for growth.  */
+  h->test = *hash_table_test_from_std (h->frozen_test);
+  ptrdiff_t size = ASIZE (h->key_and_value) / 2;
+  h->count = size;
+  ptrdiff_t index_size = hash_index_size (size);
+  h->next_free = -1;
+
+  h->hash = make_nil_vector (size);
+  h->next = make_vector (size, make_fixnum (-1));
+  h->index = make_vector (index_size, make_fixnum (-1));
 
   /* Recompute the actual hash codes for each entry in the table.
      Order is still invalid.  */
-  for (i = 0; i < count; i++)
+  for (ptrdiff_t i = 0; i < size; i++)
     {
       Lisp_Object key = HASH_KEY (h, i);
       Lisp_Object hash_code = hash_from_key (h, key);
@@ -4712,12 +4730,7 @@ hash_table_rehash (Lisp_Object hash)
       set_hash_hash_slot (h, i, hash_code);
       set_hash_next_slot (h, i, HASH_INDEX (h, start_of_bucket));
       set_hash_index_slot (h, start_of_bucket, i);
-      eassert (HASH_NEXT (h, i) != i); /* Stop loops.  */
     }
-
-  ptrdiff_t size = ASIZE (h->next);
-  for (; i + 1 < size; i++)
-    set_hash_next_slot (h, i, i + 1);
 }
 
 /* Lookup KEY in hash table H.  If HASH is non-null, return in *HASH
diff --git a/src/lisp.h b/src/lisp.h
index 48e1f943ed8..d9b828b0328 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2385,6 +2385,12 @@ INLINE int
 
 struct Lisp_Hash_Table;
 
+typedef enum {
+  Test_eql,
+  Test_eq,
+  Test_equal,
+} hash_table_std_test_t;
+
 struct hash_table_test
 {
   /* Function used to compare keys; always a bare symbol.  */
@@ -2473,6 +2479,9 @@ struct Lisp_Hash_Table
   /* Weakness of the table.  */
   hash_table_weakness_t weakness : 8;
 
+  /* Hash table test (only used when frozen in dump)  */
+  hash_table_std_test_t frozen_test : 8;
+
   /* True if the table can be purecopied.  The table cannot be
      changed afterwards.  */
   bool purecopy;
@@ -2563,7 +2572,7 @@ hash_from_key (struct Lisp_Hash_Table *h, Lisp_Object key)
   return h->test.hashfn (key, h);
 }
 
-void hash_table_rehash (Lisp_Object);
+void hash_table_thaw (Lisp_Object hash_table);
 
 /* Default size for hash tables if not specified.  */
 
@@ -4038,7 +4047,6 @@ extern void hexbuf_digest (char *, void const *, int);
 extern char *extract_data_from_object (Lisp_Object, ptrdiff_t *, ptrdiff_t *);
 EMACS_UINT hash_string (char const *, ptrdiff_t);
 EMACS_UINT sxhash (Lisp_Object);
-Lisp_Object hashfn_user_defined (Lisp_Object, struct Lisp_Hash_Table *);
 Lisp_Object make_hash_table (struct hash_table_test, EMACS_INT,
                              hash_table_weakness_t, bool);
 Lisp_Object hash_table_weakness_symbol (hash_table_weakness_t weak);
diff --git a/src/pdumper.c b/src/pdumper.c
index 8072148c542..e4349f0cb17 100644
--- a/src/pdumper.c
+++ b/src/pdumper.c
@@ -2646,34 +2646,26 @@ dump_vectorlike_generic (struct dump_context *ctx,
   return offset;
 }
 
-/* Return a vector of KEY, VALUE pairs in the given hash table H.  The
-   first H->count pairs are valid, and the rest are unbound.  */
+/* Return a vector of KEY, VALUE pairs in the given hash table H.
+   No room for growth is included.  */
 static Lisp_Object
 hash_table_contents (struct Lisp_Hash_Table *h)
 {
-  if (h->test.hashfn == hashfn_user_defined)
-    error ("cannot dump hash tables with user-defined tests");  /* Bug#36769 */
-
-  ptrdiff_t size = HASH_TABLE_SIZE (h);
+  ptrdiff_t old_size = HASH_TABLE_SIZE (h);
+  ptrdiff_t size = h->count;
   Lisp_Object key_and_value = make_uninit_vector (2 * size);
   ptrdiff_t n = 0;
 
   /* Make sure key_and_value ends up in the same order; charset.c
      relies on it by expecting hash table indices to stay constant
      across the dump.  */
-  for (ptrdiff_t i = 0; i < size; i++)
+  for (ptrdiff_t i = 0; i < old_size; i++)
     if (!NILP (HASH_HASH (h, i)))
       {
         ASET (key_and_value, n++, HASH_KEY (h, i));
         ASET (key_and_value, n++, HASH_VALUE (h, i));
       }
 
-  while (n < 2 * size)
-    {
-      ASET (key_and_value, n++, Qunbound);
-      ASET (key_and_value, n++, Qnil);
-    }
-
   return key_and_value;
 }
 
@@ -2686,25 +2678,32 @@ dump_hash_table_list (struct dump_context *ctx)
     return 0;
 }
 
-static void
-hash_table_freeze (struct Lisp_Hash_Table *h)
+static hash_table_std_test_t
+hash_table_std_test (const struct hash_table_test *t)
 {
-  ptrdiff_t npairs = ASIZE (h->key_and_value) / 2;
-  h->key_and_value = hash_table_contents (h);
-  h->next = h->hash = make_fixnum (npairs);
-  h->index = make_fixnum (ASIZE (h->index));
-  h->next_free = (npairs == h->count ? -1 : h->count);
+  if (BASE_EQ (t->name, Qeq))
+    return Test_eq;
+  if (BASE_EQ (t->name, Qeql))
+    return Test_eql;
+  if (BASE_EQ (t->name, Qequal))
+    return Test_equal;
+  error ("cannot dump hash tables with user-defined tests");  /* Bug#36769 */
 }
 
+/* Compact contents and discard inessential information from a hash table,
+   preparing it for dumping.
+   See `hash_table_thaw' for the code that restores the object to a usable
+   state. */
 static void
-hash_table_thaw (Lisp_Object hash)
+hash_table_freeze (struct Lisp_Hash_Table *h)
 {
-  struct Lisp_Hash_Table *h = XHASH_TABLE (hash);
-  h->hash = make_nil_vector (XFIXNUM (h->hash));
-  h->next = Fmake_vector (h->next, make_fixnum (-1));
-  h->index = Fmake_vector (h->index, make_fixnum (-1));
-
-  hash_table_rehash (hash);
+  h->key_and_value = hash_table_contents (h);
+  eassert (ASIZE (h->key_and_value) == h->count * 2);
+  h->next = Qnil;
+  h->hash = Qnil;
+  h->index = Qnil;
+  h->count = 0;
+  h->frozen_test = hash_table_std_test (&h->test);
 }
 
 static dump_off
@@ -2724,19 +2723,11 @@ dump_hash_table (struct dump_context *ctx, Lisp_Object object)
   dump_pseudovector_lisp_fields (ctx, &out->header, &hash->header);
   /* TODO: dump the hash bucket vectors synchronously here to keep
      them as close to the hash table as possible.  */
-  DUMP_FIELD_COPY (out, hash, count);
-  DUMP_FIELD_COPY (out, hash, next_free);
   DUMP_FIELD_COPY (out, hash, weakness);
   DUMP_FIELD_COPY (out, hash, purecopy);
   DUMP_FIELD_COPY (out, hash, mutable);
+  DUMP_FIELD_COPY (out, hash, frozen_test);
   dump_field_lv (ctx, out, hash, &hash->key_and_value, WEIGHT_STRONG);
-  dump_field_lv (ctx, out, hash, &hash->test.name, WEIGHT_STRONG);
-  dump_field_lv (ctx, out, hash, &hash->test.user_hash_function,
-                 WEIGHT_STRONG);
-  dump_field_lv (ctx, out, hash, &hash->test.user_cmp_function,
-                 WEIGHT_STRONG);
-  dump_field_emacs_ptr (ctx, out, hash, &hash->test.cmpfn);
-  dump_field_emacs_ptr (ctx, out, hash, &hash->test.hashfn);
   eassert (hash->next_weak == NULL);
   return finish_dump_pvec (ctx, &out->header);
 }