From f378ed1a0b1ca2ceed5afabcf5f303ae339039ba Mon Sep 17 00:00:00 2001
From: Paul Eggert
Date: Mon, 22 Jul 2019 21:27:33 -0700
Subject: Avoid overexposing fixnums for hash codes

Following a suggestion by Stefan Monnier in:
https://lists.gnu.org/r/emacs-devel/2019-07/msg00530.html
* doc/lispref/hash.texi (Creating Hash, Defining Hash):
* src/fns.c (Fsxhash_eq, Fsxhash_eql, Fsxhash_equal, Fmake_hash_table):
Don’t insist that hash codes be fixnums, reverting
the recent doc changes to the contrary.
* src/bytecode.c (exec_byte_code): Special-case only the eq case,
as the others aren’t worth tuning now that we treat bignum hashes
like fixnums.
* src/fns.c (hashfn_user_defined): If the hash code is a bignum,
reduce its hash down to a fixnum.
---
 src/bytecode.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

(limited to 'src/bytecode.c')

diff --git a/src/bytecode.c b/src/bytecode.c
index d668a9a6a15..9aad1eb642b 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -1406,18 +1406,12 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
 
             /* h->count is a faster approximation for HASH_TABLE_SIZE (h)
                here. */
-            if (h->count <= 5)
+            if (h->count <= 5 && !h->test.cmpfn)
               { /* Do a linear search if there are not many cases
                    FIXME: 5 is arbitrarily chosen.  */
-		Lisp_Object hash_code
-		  = h->test.cmpfn ? h->test.hashfn (v1, h) : Qnil;
-
-                for (i = h->count; 0 <= --i; )
-                  if (EQ (v1, HASH_KEY (h, i))
-                      || (h->test.cmpfn
-                          && EQ (hash_code, HASH_HASH (h, i))
-			  && !NILP (h->test.cmpfn (v1, HASH_KEY (h, i), h))))
-                    break;
+		for (i = h->count; 0 <= --i; )
+		  if (EQ (v1, HASH_KEY (h, i)))
+		    break;
               }
             else
               i = hash_lookup (h, v1, NULL);
-- 
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