From 0129e88cee5f5ac295c311d5d94f2bb6a2f475f6 Mon Sep 17 00:00:00 2001
From: Nathan Moinvaziri <nathan@nathanm.com>
Date: Tue, 21 Apr 2020 10:29:37 -0700
Subject: Removed TRIGGER_LEVEL byte masking from INSERT_STRING and UPDATE_HASH
 due to poor performance on levels 6 and 9 especially with optimized versions
 of UPDATE_HASH.

From commit d306c75d3bb36cba73aec9b3b3ca378e31d1799e:

.. we hash 4 bytes, instead of 3, for certain levels. This shortens the hash chains, and also improves the quality
of each hash entry.
---
 insert_string.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

(limited to 'insert_string.c')

diff --git a/insert_string.c b/insert_string.c
index 4e4c628bfb..e9efd517f8 100644
--- a/insert_string.c
+++ b/insert_string.c
@@ -17,17 +17,10 @@
 
 #if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
 #  define UPDATE_HASH(s, h, val) \
-    do {\
-        if (s->level < TRIGGER_LEVEL)\
-            h = (3483 * ((val) & 0xff) +\
-                 23081* (((val) >> 8) & 0xff) +\
-                 6954 * (((val) >> 16) & 0xff) +\
-                 20947* (((val) >> 24) & 0xff));\
-        else\
-            h = (25881* (((val)) & 0xff) +\
-                 24674* (((val) >> 8) & 0xff) +\
-                 25811* (((val) >> 16) & 0xff));\
-    } while (0)
+    h = (3483  * ((val) & 0xff) +\
+         23081 * (((val) >> 8) & 0xff) +\
+         6954  * (((val) >> 16) & 0xff) +\
+         20947 * (((val) >> 24) & 0xff));
 #else
 #  define UPDATE_HASH(s, h, val)\
     h = (s->ins_h = ((s->ins_h << s->hash_shift) ^ ((val) >> ((MIN_MATCH - 1) * 8))) & s->hash_mask)
-- 
cgit 0.0.5-2-1-g0f52