From: Nicholas Clark <nick@ccl4.org>
Date: Fri, 9 Dec 2005 23:09:42 +0000 (+0000)
Subject: A better hash for PTR_TABLE_HASH (?)
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=7119fd33ffc5ef947b59b6096cf5249ee05d4397;p=p5sagit%2Fp5-mst-13.2.git

A better hash for PTR_TABLE_HASH (?)

p4raw-id: //depot/perl@26315
---

diff --git a/sv.c b/sv.c
index 9ed37cb..30b499d 100644
--- a/sv.c
+++ b/sv.c
@@ -9031,11 +9031,8 @@ Perl_ptr_table_new(pTHX)
     return tbl;
 }
 
-#if (PTRSIZE == 8)
-#  define PTR_TABLE_HASH(ptr) (PTR2UV(ptr) >> 3)
-#else
-#  define PTR_TABLE_HASH(ptr) (PTR2UV(ptr) >> 2)
-#endif
+#define PTR_TABLE_HASH(ptr) \
+  ((PTR2UV(ptr) >> 3) ^ (PTR2UV(ptr) >> (3 + 7)) ^ (PTR2UV(ptr) >> (3 + 17)))
 
 /* 
    we use the PTE_SVSLOT 'reservation' made above, both here (in the