From c2c435f95d6ef7a559131be4e663ac06f4f9aaf0 Mon Sep 17 00:00:00 2001
From: Evgeniy Stepanov <eugeni.stepanov@gmail.com>
Date: Thu, 10 Jul 2014 11:02:33 +0000
Subject: [PATCH] [msan] Switch chained origins hash to murmur2.

llvm-svn: 212704
---
 compiler-rt/lib/msan/msan_chained_origin_depot.cc | 25 ++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/compiler-rt/lib/msan/msan_chained_origin_depot.cc b/compiler-rt/lib/msan/msan_chained_origin_depot.cc
index 95f0a804..faf0461 100644
--- a/compiler-rt/lib/msan/msan_chained_origin_depot.cc
+++ b/compiler-rt/lib/msan/msan_chained_origin_depot.cc
@@ -19,7 +19,30 @@ namespace __msan {
 struct ChainedOriginDepotDesc {
   u32 here_id;
   u32 prev_id;
-  u32 hash() const { return (here_id * 0x1f1f1f1f) ^ prev_id; }
+  u32 hash() const {
+    const u32 m = 0x5bd1e995;
+    const u32 seed = 0x9747b28c;
+    const u32 r = 24;
+    u32 h = seed;
+    u32 k = here_id;
+    k *= m;
+    k ^= k >> r;
+    k *= m;
+    h *= m;
+    h ^= k;
+
+    k = prev_id;
+    k *= m;
+    k ^= k >> r;
+    k *= m;
+    h *= m;
+    h ^= k;
+
+    h ^= h >> 13;
+    h *= m;
+    h ^= h >> 15;
+    return h;
+  }
   bool is_valid() { return true; }
 };
 
-- 
2.7.4