From 6d56fd067e219803e194b8b95aa00e558250cfec Mon Sep 17 00:00:00 2001
From: normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 22 Jan 2015 07:48:59 +0000
Subject: fix flonum hashing regression from r45384

* st.c (st_numhash): mix float value for flonum
* hash.c (rb_any_hash): ditto
* benchmark/bm_hash_aref_flo.rb: new benchmark
* benchmark/bm_hash_ident_flo.rb: ditto
  [Bug #10761]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49376 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 st.c | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'st.c')

diff --git a/st.c b/st.c
index b7f66d08b4..e630c1ec48 100644
--- a/st.c
+++ b/st.c
@@ -1761,6 +1761,15 @@ st_numhash(st_data_t n)
      * - (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));
 }
-- 
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