hash.c: move Hash specific functions

* hash.c (rb_ident_hash): move compare_by_identity specific
  function from st.c.

* hash.c (rb_ident_hash_new): ditto from thread.c.

* st.c (st_numhash): remove ruby's Hash specific implementation.

* thread.c (recursive_list_access): use rb_ident_hash_new().

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49386 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 41 insertions, 1 deletions

diff --git a/hash.c b/hash.c
index b7e2c66849..bae417c642 100644
--- a/hash.c
+++ b/hash.c
@@ -177,7 +177,39 @@ static const struct st_hash_type objhash = {
     rb_any_hash,
 };
 
-#define identhash st_hashtype_num
+#define rb_ident_cmp st_numcmp
+
+static st_index_t
+rb_ident_hash(st_data_t n)
+{
+    /*
+     * This hash function is lightly-tuned for Ruby.  Further tuning
+     * should be possible.  Notes:
+     *
+     * - (n >> 3) alone is great for heap objects and OK for fixnum,
+     *   however symbols perform poorly.
+     * - (n >> (RUBY_SPECIAL_SHIFT+3)) was added to make symbols hash well,
+     *   n.b.: +3 to remove ID scope, +1 worked well initially, too
+     * - (n << 3) was finally added to avoid losing bits for fixnums
+     * - avoid expensive modulo instructions, it is currently only
+     *   shifts and bitmask operations.
+     * - flonum (on 64-bit) is pathologically bad, mix the actual
+     *   float value in, but do not use the float value as-is since
+     *   many integers get interpreted as 2.0 or -2.0 [Bug #10761]
+     */
+#ifdef USE_FLONUM /* RUBY */
+    if (FLONUM_P(n)) {
+	n ^= (st_data_t)rb_float_value(n);
+    }
+#endif
+
+    return (st_index_t)((n>>(RUBY_SPECIAL_SHIFT+3)|(n<<3)) ^ (n>>3));
+}
+
+static const struct st_hash_type identhash = {
+    rb_ident_cmp,
+    rb_ident_hash,
+};
 
 typedef int st_foreach_func(st_data_t, st_data_t, st_data_t);
 
@@ -2509,6 +2541,14 @@ rb_hash_compare_by_id_p(VALUE hash)
     return Qfalse;
 }
 
+VALUE
+rb_ident_hash_new(void)
+{
+    VALUE hash = rb_hash_new();
+    RHASH(hash)->ntbl = st_init_table(&identhash);
+    return hash;
+}
+
 static int
 any_p_i(VALUE key, VALUE value, VALUE arg)
 {