Store hash values as integers instead of Lisp_Object

This improves typing, saves pointless tagging and untagging, and
prepares for further changes. The new typedef hash_hash_t is an alias
for EMACS_UINT, and hash values are still limited to the fixnum range.
We now use hash_unused instead of Qnil to mark unused entries.

* src/lisp.h (hash_hash_t): New typedef for EMACS_UINT.
(hash_unused): New constant.
(struct hash_table_test): `hashfn` now returns
hash_hash_t.  All callers and implementations changed.
(struct Lisp_Hash_Table): Retype hash vector to an array of
hash_hash_t.  All code using it changed accordingly.
(HASH_HASH, hash_from_key):
* src/fns.c (set_hash_index_slot, hash_index_index)
(hash_lookup_with_hash, hash_lookup_get_hash, hash_put):
(hash_lookup, hash_put): Retype hash value arguments
and return values.  All callers adapted.

11 files changed, 75 insertions, 57 deletions

diff --git a/src/category.c b/src/category.c
index 583cdb3eebb..e7fbf1ff500 100644
--- a/src/category.c
+++ b/src/category.c
@@ -53,7 +53,7 @@ hash_get_category_set (Lisp_Object table, Lisp_Object category_set)
       (table, 1,
        make_hash_table (hashtest_equal, DEFAULT_HASH_SIZE, Weak_None, false));
   struct Lisp_Hash_Table *h = XHASH_TABLE (XCHAR_TABLE (table)->extras[1]);
-  Lisp_Object hash;
+  hash_hash_t hash;
   ptrdiff_t i = hash_lookup (h, category_set, &hash);
   if (i >= 0)
     return HASH_KEY (h, i);
diff --git a/src/charset.c b/src/charset.c
index 3aa105e57bd..add3bf846f8 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -850,7 +850,6 @@ usage: (define-charset-internal ...)  */)
   /* Charset attr vector.  */
   Lisp_Object attrs;
   Lisp_Object val;
-  Lisp_Object hash_code;
   struct Lisp_Hash_Table *hash_table = XHASH_TABLE (Vcharset_hash_table);
   int i, j;
   struct charset charset;
@@ -1108,6 +1107,7 @@ usage: (define-charset-internal ...)  */)
   CHECK_LIST (args[charset_arg_plist]);
   ASET (attrs, charset_plist, args[charset_arg_plist]);
 
+  hash_hash_t hash_code;
   charset.hash_index = hash_lookup (hash_table, args[charset_arg_name],
                                     &hash_code);
   if (charset.hash_index >= 0)
diff --git a/src/composite.c b/src/composite.c
index ed1aeb380a0..bd69a953e3f 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -166,7 +166,7 @@ ptrdiff_t
 get_composition_id (ptrdiff_t charpos, ptrdiff_t bytepos, ptrdiff_t nchars,
                     Lisp_Object prop, Lisp_Object string)
 {
-  Lisp_Object id, length, components, key, *key_contents, hash_code;
+  Lisp_Object id, length, components, key, *key_contents;
   ptrdiff_t glyph_len;
   struct Lisp_Hash_Table *hash_table = XHASH_TABLE (composition_hash_table);
   ptrdiff_t hash_index;
@@ -240,6 +240,7 @@ get_composition_id (ptrdiff_t charpos, ptrdiff_t bytepos, ptrdiff_t nchars,
   else
     goto invalid_composition;
 
+  hash_hash_t hash_code;
   hash_index = hash_lookup (hash_table, key, &hash_code);
   if (hash_index >= 0)
     {
@@ -653,7 +654,7 @@ composition_gstring_put_cache (Lisp_Object gstring, ptrdiff_t len)
 {
   struct Lisp_Hash_Table *h = XHASH_TABLE (gstring_hash_table);
   Lisp_Object header = LGSTRING_HEADER (gstring);
-  Lisp_Object hash = hash_from_key (h, header);
+  EMACS_UINT hash = hash_from_key (h, header);
   if (len < 0)
     {
       ptrdiff_t glyph_len = LGSTRING_GLYPH_LEN (gstring);
diff --git a/src/emacs-module.c b/src/emacs-module.c
index 60aed68f2cd..728da8c2882 100644
--- a/src/emacs-module.c
+++ b/src/emacs-module.c
@@ -427,7 +427,8 @@ module_make_global_ref (emacs_env *env, emacs_value value)
 {
   MODULE_FUNCTION_BEGIN (NULL);
   struct Lisp_Hash_Table *h = XHASH_TABLE (Vmodule_refs_hash);
-  Lisp_Object new_obj = value_to_lisp (value), hashcode;
+  Lisp_Object new_obj = value_to_lisp (value);
+  hash_hash_t hashcode;
   ptrdiff_t i = hash_lookup (h, new_obj, &hashcode);
 
   /* Note: This approach requires the garbage collector to never move
diff --git a/src/fns.c b/src/fns.c
index 3aca588a8a5..5a3c51c8412 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -2759,7 +2759,7 @@ internal_equal (Lisp_Object o1, Lisp_Object o2, enum equal_kind equal_kind,
         case Lisp_Cons: case Lisp_Vectorlike:
           {
             struct Lisp_Hash_Table *h = XHASH_TABLE (ht);
-            Lisp_Object hash;
+            hash_hash_t hash;
             ptrdiff_t i = hash_lookup (h, o1, &hash);
             if (i >= 0)
               { /* `o1' was seen already.  */
@@ -4279,7 +4279,7 @@ set_hash_next_slot (struct Lisp_Hash_Table *h, ptrdiff_t idx, ptrdiff_t val)
   h->next[idx] = val;
 }
 static void
-set_hash_hash_slot (struct Lisp_Hash_Table *h, ptrdiff_t idx, Lisp_Object val)
+set_hash_hash_slot (struct Lisp_Hash_Table *h, ptrdiff_t idx, hash_hash_t val)
 {
   eassert (idx >= 0 && idx < h->table_size);
   h->hash[idx] = val;
@@ -4450,41 +4450,42 @@ cmpfn_user_defined (Lisp_Object key1, Lisp_Object key2,
 
 /* Ignore H and return a hash code for KEY which uses 'eq' to compare keys.  */
 
-static Lisp_Object
+static hash_hash_t
 hashfn_eq (Lisp_Object key, struct Lisp_Hash_Table *h)
 {
   if (symbols_with_pos_enabled && SYMBOL_WITH_POS_P (key))
     key = SYMBOL_WITH_POS_SYM (key);
-  return make_ufixnum (XHASH (key) ^ XTYPE (key));
+  return XHASH (key) ^ XTYPE (key);
 }
 
 /* Ignore H and return a hash code for KEY which uses 'equal' to compare keys.
    The hash code is at most INTMASK.  */
 
-static Lisp_Object
+static hash_hash_t
 hashfn_equal (Lisp_Object key, struct Lisp_Hash_Table *h)
 {
-  return make_ufixnum (sxhash (key));
+  return sxhash (key);
 }
 
 /* Ignore H and return a hash code for KEY which uses 'eql' to compare keys.
    The hash code is at most INTMASK.  */
 
-static Lisp_Object
+static hash_hash_t
 hashfn_eql (Lisp_Object key, struct Lisp_Hash_Table *h)
 {
-  return (FLOATP (key) || BIGNUMP (key) ? hashfn_equal : hashfn_eq) (key, h);
+  return (FLOATP (key) || BIGNUMP (key)
+          ? hashfn_equal (key, h) : hashfn_eq (key, h));
 }
 
 /* Given H, return a hash code for KEY which uses a user-defined
    function to compare keys.  */
 
-static Lisp_Object
+static hash_hash_t
 hashfn_user_defined (Lisp_Object key, struct Lisp_Hash_Table *h)
 {
   Lisp_Object args[] = { h->test.user_hash_function, key };
   Lisp_Object hash = hash_table_user_defined_call (ARRAYELTS (args), args, h);
-  return FIXNUMP (hash) ? hash : make_ufixnum (sxhash (hash));
+  return FIXNUMP (hash) ? XUFIXNUM(hash) : sxhash (hash);
 }
 
 struct hash_table_test const
@@ -4584,7 +4585,8 @@ make_hash_table (struct hash_table_test test, EMACS_INT size,
         h->key_and_value[i] = HASH_UNUSED_ENTRY_KEY;
 
       h->hash = hash_table_alloc_bytes (size * sizeof *h->hash);
-      memclear (h->hash, size * sizeof *h->hash);
+      for (ptrdiff_t i = 0; i < size; i++)
+        h->hash[i] = hash_unused;
 
       h->next = hash_table_alloc_bytes (size * sizeof *h->next);
       for (ptrdiff_t i = 0; i < size - 1; i++)
@@ -4650,10 +4652,10 @@ copy_hash_table (struct Lisp_Hash_Table *h1)
 
 /* Compute index into the index vector from a hash value.  */
 static inline ptrdiff_t
-hash_index_index (struct Lisp_Hash_Table *h, Lisp_Object hash_code)
+hash_index_index (struct Lisp_Hash_Table *h, hash_hash_t hash)
 {
   eassert (h->index_size > 0);
-  return XUFIXNUM (hash_code) % h->index_size;
+  return hash % h->index_size;
 }
 
 /* Resize hash table H if it's too full.  If H cannot be resized
@@ -4690,9 +4692,10 @@ maybe_resize_hash_table (struct Lisp_Hash_Table *h)
       for (ptrdiff_t i = 2 * old_size; i < 2 * new_size; i++)
         key_and_value[i] = HASH_UNUSED_ENTRY_KEY;
 
-      Lisp_Object *hash = hash_table_alloc_bytes (new_size * sizeof *hash);
+      hash_hash_t *hash = hash_table_alloc_bytes (new_size * sizeof *hash);
       memcpy (hash, h->hash, old_size * sizeof *hash);
-      memclear (hash + old_size, (new_size - old_size) * word_size);
+      for (ptrdiff_t i = old_size; i < new_size; i++)
+        hash[i] = hash_unused;
 
       ptrdiff_t old_index_size = h->index_size;
       ptrdiff_t index_size = hash_index_size (new_size);
@@ -4723,7 +4726,7 @@ maybe_resize_hash_table (struct Lisp_Hash_Table *h)
       /* Rehash: all data occupy entries 0..old_size-1.  */
       for (ptrdiff_t i = 0; i < old_size; i++)
         {
-          Lisp_Object hash_code = HASH_HASH (h, i);
+          hash_hash_t hash_code = HASH_HASH (h, i);
           ptrdiff_t start_of_bucket = hash_index_index (h, hash_code);
           set_hash_next_slot (h, i, HASH_INDEX (h, start_of_bucket));
           set_hash_index_slot (h, start_of_bucket, i);
@@ -4764,7 +4767,8 @@ hash_table_thaw (Lisp_Object hash_table)
   h->next_free = -1;
 
   h->hash = hash_table_alloc_bytes (size * sizeof *h->hash);
-  memclear (h->hash, size * sizeof *h->hash);
+  for (ptrdiff_t i = 0; i < size; i++)
+    h->hash[i] = hash_unused;
 
   h->next = hash_table_alloc_bytes (size * sizeof *h->next);
   for (ptrdiff_t i = 0; i < size; i++)
@@ -4779,7 +4783,7 @@ hash_table_thaw (Lisp_Object hash_table)
   for (ptrdiff_t i = 0; i < size; i++)
     {
       Lisp_Object key = HASH_KEY (h, i);
-      Lisp_Object hash_code = hash_from_key (h, key);
+      hash_hash_t hash_code = hash_from_key (h, key);
       ptrdiff_t start_of_bucket = hash_index_index (h, hash_code);
       set_hash_hash_slot (h, i, hash_code);
       set_hash_next_slot (h, i, HASH_INDEX (h, start_of_bucket));
@@ -4792,9 +4796,9 @@ hash_table_thaw (Lisp_Object hash_table)
    matching KEY, or -1 if not found.  */
 
 ptrdiff_t
-hash_lookup (struct Lisp_Hash_Table *h, Lisp_Object key, Lisp_Object *hash)
+hash_lookup (struct Lisp_Hash_Table *h, Lisp_Object key, hash_hash_t *hash)
 {
-  Lisp_Object hash_code = hash_from_key (h, key);
+  hash_hash_t hash_code = hash_from_key (h, key);
   if (hash)
     *hash = hash_code;
 
@@ -4803,7 +4807,7 @@ hash_lookup (struct Lisp_Hash_Table *h, Lisp_Object key, Lisp_Object *hash)
   for (i = HASH_INDEX (h, start_of_bucket); 0 <= i; i = HASH_NEXT (h, i))
     if (EQ (key, HASH_KEY (h, i))
         || (h->test.cmpfn
-            && EQ (hash_code, HASH_HASH (h, i))
+            && hash_code == HASH_HASH (h, i)
             && !NILP (h->test.cmpfn (key, HASH_KEY (h, i), h))))
       break;
 
@@ -4824,7 +4828,7 @@ check_mutable_hash_table (Lisp_Object obj, struct Lisp_Hash_Table *h)
 
 ptrdiff_t
 hash_put (struct Lisp_Hash_Table *h, Lisp_Object key, Lisp_Object value,
-          Lisp_Object hash)
+          hash_hash_t hash)
 {
   /* Increment count after resizing because resizing may fail.  */
   maybe_resize_hash_table (h);
@@ -4832,7 +4836,7 @@ hash_put (struct Lisp_Hash_Table *h, Lisp_Object key, Lisp_Object value,
 
   /* Store key/value in the key_and_value vector.  */
   ptrdiff_t i = h->next_free;
-  eassert (NILP (HASH_HASH (h, i)));
+  eassert (HASH_HASH (h, i) == hash_unused);
   eassert (hash_unused_entry_key_p (HASH_KEY (h, i)));
   h->next_free = HASH_NEXT (h, i);
   set_hash_key_slot (h, i, key);
@@ -4854,8 +4858,8 @@ hash_put (struct Lisp_Hash_Table *h, Lisp_Object key, Lisp_Object value,
 void
 hash_remove_from_table (struct Lisp_Hash_Table *h, Lisp_Object key)
 {
-  Lisp_Object hash_code = hash_from_key (h, key);
-  ptrdiff_t start_of_bucket = hash_index_index (h, hash_code);
+  hash_hash_t hashval = hash_from_key (h, key);
+  ptrdiff_t start_of_bucket = hash_index_index (h, hashval);
   ptrdiff_t prev = -1;
 
   for (ptrdiff_t i = HASH_INDEX (h, start_of_bucket);
@@ -4864,7 +4868,7 @@ hash_remove_from_table (struct Lisp_Hash_Table *h, Lisp_Object key)
     {
       if (EQ (key, HASH_KEY (h, i))
           || (h->test.cmpfn
-              && EQ (hash_code, HASH_HASH (h, i))
+              && hashval == HASH_HASH (h, i)
               && !NILP (h->test.cmpfn (key, HASH_KEY (h, i), h))))
         {
           /* Take entry out of collision chain.  */
@@ -4877,7 +4881,7 @@ hash_remove_from_table (struct Lisp_Hash_Table *h, Lisp_Object key)
              the free list.  */
           set_hash_key_slot (h, i, HASH_UNUSED_ENTRY_KEY);
           set_hash_value_slot (h, i, Qnil);
-          set_hash_hash_slot (h, i, Qnil);
+          set_hash_hash_slot (h, i, hash_unused);
           set_hash_next_slot (h, i, h->next_free);
           h->next_free = i;
           h->count--;
@@ -4898,9 +4902,9 @@ hash_clear (struct Lisp_Hash_Table *h)
   if (h->count > 0)
     {
       ptrdiff_t size = HASH_TABLE_SIZE (h);
-      memclear (h->hash, size * word_size);
       for (ptrdiff_t i = 0; i < size; i++)
         {
+          set_hash_hash_slot (h, i, hash_unused);
           set_hash_next_slot (h, i, i < size - 1 ? i + 1 : -1);
           set_hash_key_slot (h, i, HASH_UNUSED_ENTRY_KEY);
           set_hash_value_slot (h, i, Qnil);
@@ -4983,7 +4987,7 @@ sweep_weak_table (struct Lisp_Hash_Table *h, bool remove_entries_p)
                   /* Clear key, value, and hash.  */
                   set_hash_key_slot (h, i, HASH_UNUSED_ENTRY_KEY);
                   set_hash_value_slot (h, i, Qnil);
-                  set_hash_hash_slot (h, i, Qnil);
+                  set_hash_hash_slot (h, i, hash_unused);
 
                   eassert (h->count != 0);
                   h->count--;
@@ -5269,7 +5273,7 @@ If (eq A B), then (= (sxhash-eq A) (sxhash-eq B)).
 Hash codes are not guaranteed to be preserved across Emacs sessions.  */)
   (Lisp_Object obj)
 {
-  return hashfn_eq (obj, NULL);
+  return make_ufixnum (hashfn_eq (obj, NULL));
 }
 
 DEFUN ("sxhash-eql", Fsxhash_eql, Ssxhash_eql, 1, 1, 0,
@@ -5280,7 +5284,7 @@ isn't necessarily true.
 Hash codes are not guaranteed to be preserved across Emacs sessions.  */)
   (Lisp_Object obj)
 {
-  return hashfn_eql (obj, NULL);
+  return make_ufixnum (hashfn_eql (obj, NULL));
 }
 
 DEFUN ("sxhash-equal", Fsxhash_equal, Ssxhash_equal, 1, 1, 0,
@@ -5291,7 +5295,7 @@ opposite isn't necessarily true.
 Hash codes are not guaranteed to be preserved across Emacs sessions.  */)
   (Lisp_Object obj)
 {
-  return hashfn_equal (obj, NULL);
+  return make_ufixnum (hashfn_equal (obj, NULL));
 }
 
 DEFUN ("sxhash-equal-including-properties", Fsxhash_equal_including_properties,
@@ -5315,7 +5319,7 @@ Hash codes are not guaranteed to be preserved across Emacs sessions.  */)
                                          sxhash (CDR (collector)))));
     }
 
-  return hashfn_equal (obj, NULL);
+  return make_ufixnum (hashfn_equal (obj, NULL));
 }
 
 DEFUN ("make-hash-table", Fmake_hash_table, Smake_hash_table, 0, MANY, 0,
@@ -5549,7 +5553,7 @@ VALUE.  In any case, return VALUE.  */)
   struct Lisp_Hash_Table *h = check_hash_table (table);
   check_mutable_hash_table (table, h);
 
-  Lisp_Object hash;
+  EMACS_UINT hash;
   ptrdiff_t i = hash_lookup (h, key, &hash);
   if (i >= 0)
     set_hash_value_slot (h, i, value);
@@ -5650,7 +5654,7 @@ Internal use only. */)
     {
       Lisp_Object bucket = Qnil;
       for (ptrdiff_t j = HASH_INDEX (h, i); j != -1; j = HASH_NEXT (h, j))
-        bucket = Fcons (Fcons (HASH_KEY (h, j), HASH_HASH (h, j)),
+        bucket = Fcons (Fcons (HASH_KEY (h, j), make_int (HASH_HASH (h, j))),
                         bucket);
       if (!NILP (bucket))
         ret = Fcons (Fnreverse (bucket), ret);
diff --git a/src/image.c b/src/image.c
index 9c100213590..55b027d568b 100644
--- a/src/image.c
+++ b/src/image.c
@@ -6079,8 +6079,9 @@ xpm_put_color_table_h (Lisp_Object color_table,
                        Lisp_Object color)
 {
   struct Lisp_Hash_Table *table = XHASH_TABLE (color_table);
-  Lisp_Object chars = make_unibyte_string (chars_start, chars_len), hash_code;
+  Lisp_Object chars = make_unibyte_string (chars_start, chars_len);
 
+  hash_hash_t hash_code;
   hash_lookup (table, chars, &hash_code);
   hash_put (table, chars, color, hash_code);
 }
diff --git a/src/json.c b/src/json.c
index d98b312ecc9..1bea4baa8ba 100644
--- a/src/json.c
+++ b/src/json.c
@@ -879,7 +879,8 @@ json_to_lisp (json_t *json, const struct json_configuration *conf)
               json_t *value;
               json_object_foreach (json, key_str, value)
                 {
-                  Lisp_Object key = build_string_from_utf8 (key_str), hash;
+                  Lisp_Object key = build_string_from_utf8 (key_str);
+                  hash_hash_t hash;
                   ptrdiff_t i = hash_lookup (h, key, &hash);
                   /* Keys in JSON objects are unique, so the key can't
                      be present yet.  */
diff --git a/src/lisp.h b/src/lisp.h
index dd457392cca..474498094c9 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2385,6 +2385,10 @@ INLINE int
 
 struct Lisp_Hash_Table;
 
+/* The type of a hash value stored in the table.
+   It's unsigned and a subtype of EMACS_UINT.  */
+typedef EMACS_UINT hash_hash_t;
+
 typedef enum {
   Test_eql,
   Test_eq,
@@ -2406,7 +2410,7 @@ struct hash_table_test
   Lisp_Object (*cmpfn) (Lisp_Object, Lisp_Object, struct Lisp_Hash_Table *);
 
   /* C function to compute hash code.  */
-  Lisp_Object (*hashfn) (Lisp_Object, struct Lisp_Hash_Table *);
+  hash_hash_t (*hashfn) (Lisp_Object, struct Lisp_Hash_Table *);
 };
 
 typedef enum {
@@ -2421,6 +2425,11 @@ typedef enum {
                             both key and value remain.  */
 } hash_table_weakness_t;
 
+/* An value that marks an unused hash entry.
+   Any hash_hash_t value that is not a valid fixnum will do here.  */
+enum { hash_unused = (hash_hash_t)MOST_POSITIVE_FIXNUM + 1 };
+verify (FIXNUM_OVERFLOW_P (hash_unused));
+
 struct Lisp_Hash_Table
 {
   union vectorlike_header header;
@@ -2462,9 +2471,9 @@ struct Lisp_Hash_Table
 
   ptrdiff_t table_size;   /* Size of the next and hash vectors.  */
 
-  /* Vector of hash codes.  Each entry is either a fixnum, or nil if unused.
+  /* Vector of hash codes.  The value hash_unused marks an unused table entry.
      This vector is table_size entries long.  */
-  Lisp_Object *hash;
+  hash_hash_t *hash;
 
   /* Vector used to chain entries.  If entry I is free, next[I] is the
      entry number of the next free item.  If entry I is non-free,
@@ -2553,7 +2562,7 @@ HASH_VALUE (const struct Lisp_Hash_Table *h, ptrdiff_t idx)
 }
 
 /* Value is the hash code computed for entry IDX in hash table H.  */
-INLINE Lisp_Object
+INLINE hash_hash_t
 HASH_HASH (const struct Lisp_Hash_Table *h, ptrdiff_t idx)
 {
   eassert (idx >= 0 && idx < h->table_size);
@@ -2567,8 +2576,8 @@ HASH_TABLE_SIZE (const struct Lisp_Hash_Table *h)
   return h->table_size;
 }
 
-/* Compute hash value for KEY in hash table H.  */
-INLINE Lisp_Object
+/* Hash value for KEY in hash table H.  */
+INLINE hash_hash_t
 hash_from_key (struct Lisp_Hash_Table *h, Lisp_Object key)
 {
   return h->test.hashfn (key, h);
@@ -4054,9 +4063,9 @@ EMACS_UINT sxhash (Lisp_Object);
 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);
-ptrdiff_t hash_lookup (struct Lisp_Hash_Table *, Lisp_Object, Lisp_Object *);
+ptrdiff_t hash_lookup (struct Lisp_Hash_Table *, Lisp_Object, hash_hash_t *);
 ptrdiff_t hash_put (struct Lisp_Hash_Table *, Lisp_Object, Lisp_Object,
-                    Lisp_Object);
+                    hash_hash_t);
 void hash_remove_from_table (struct Lisp_Hash_Table *, Lisp_Object);
 extern struct hash_table_test const hashtest_eq, hashtest_eql, hashtest_equal;
 extern void validate_subarray (Lisp_Object, Lisp_Object, Lisp_Object,
diff --git a/src/lread.c b/src/lread.c
index 284536fc81f..9ad4d35c0c2 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -4255,7 +4255,7 @@ read0 (Lisp_Object readcharfun, bool locate_syms)
                         struct Lisp_Hash_Table *h
                           = XHASH_TABLE (read_objects_map);
                         Lisp_Object number = make_fixnum (n);
-                        Lisp_Object hash;
+                        hash_hash_t hash;
                         ptrdiff_t i = hash_lookup (h, number, &hash);
                         if (i >= 0)
                           /* Not normal, but input could be malformed.  */
@@ -4571,7 +4571,7 @@ read0 (Lisp_Object readcharfun, bool locate_syms)
 
                 struct Lisp_Hash_Table *h2
                   = XHASH_TABLE (read_objects_completed);
-                Lisp_Object hash;
+                hash_hash_t hash;
                 ptrdiff_t i = hash_lookup (h2, placeholder, &hash);
                 eassert (i < 0);
                 hash_put (h2, placeholder, Qnil, hash);
@@ -4586,7 +4586,7 @@ read0 (Lisp_Object readcharfun, bool locate_syms)
                   {
                     struct Lisp_Hash_Table *h2
                       = XHASH_TABLE (read_objects_completed);
-                    Lisp_Object hash;
+                    hash_hash_t hash;
                     ptrdiff_t i = hash_lookup (h2, obj, &hash);
                     eassert (i < 0);
                     hash_put (h2, obj, Qnil, hash);
@@ -4598,7 +4598,7 @@ read0 (Lisp_Object readcharfun, bool locate_syms)
 
                 /* ...and #n# will use the real value from now on.  */
                 struct Lisp_Hash_Table *h = XHASH_TABLE (read_objects_map);
-                Lisp_Object hash;
+                hash_hash_t hash;
                 ptrdiff_t i = hash_lookup (h, e->u.numbered.number, &hash);
                 eassert (i >= 0);
                 set_hash_value_slot (h, i, obj);
diff --git a/src/macfont.m b/src/macfont.m
index 8aba440d196..dcaa85bea05 100644
--- a/src/macfont.m
+++ b/src/macfont.m
@@ -980,7 +980,7 @@ macfont_invalidate_family_cache (void)
       ptrdiff_t i, size = HASH_TABLE_SIZE (h);
 
       for (i = 0; i < size; ++i)
-        if (!NILP (HASH_HASH (h, i)))
+        if (HASH_HASH (h, i) != hash_unused)
           {
             Lisp_Object value = HASH_VALUE (h, i);
 
@@ -1017,12 +1017,13 @@ macfont_set_family_cache (Lisp_Object symbol, CFStringRef string)
 {
   struct Lisp_Hash_Table *h;
   ptrdiff_t i;
-  Lisp_Object hash, value;
+  Lisp_Object value;
 
   if (!HASH_TABLE_P (macfont_family_cache))
     macfont_family_cache = CALLN (Fmake_hash_table, QCtest, Qeq);
 
   h = XHASH_TABLE (macfont_family_cache);
+  hash_hash_t hash;
   i = hash_lookup (h, symbol, &hash);
   value = string ? make_mint_ptr ((void *) CFRetain (string)) : Qnil;
   if (i >= 0)
diff --git a/src/pdumper.c b/src/pdumper.c
index 8a93c45e07b..5ed91c668df 100644
--- a/src/pdumper.c
+++ b/src/pdumper.c
@@ -2661,7 +2661,7 @@ hash_table_contents (struct Lisp_Hash_Table *h)
      relies on it by expecting hash table indices to stay constant
      across the dump.  */
   for (ptrdiff_t i = 0; i < old_size; i++)
-    if (!NILP (HASH_HASH (h, i)))
+    if (HASH_HASH (h, i) != hash_unused)
       {
         key_and_value[n++] = HASH_KEY (h, i);
         key_and_value[n++] = HASH_VALUE (h, i);