From: Marco Costalba <mcostalba@gmail.com>
Date: Tue, 3 May 2011 07:54:22 +0000 (+0200)
Subject: Reintroduce permanent PV entries in TT
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=5ef2b8c4940bd2809bc1477c0ef0b0c38b19d5f7;hp=9c5a53ca450ca7ed24e476a945f70804939cadf3

Reintroduce permanent PV entries in TT

We are now ready to release so restore this
improvment before 2.1

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---

diff --git a/src/tt.cpp b/src/tt.cpp
index 14217e8d..86b16c85 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -107,7 +107,7 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d,
 
       // Implement replace strategy
       c1 = (replace->generation() == generation ?  2 : 0);
-      c2 = (tte->generation() == generation ? -2 : 0);
+      c2 = (tte->generation() == generation || tte->type() == VALUE_TYPE_EXACT ? -2 : 0);
       c3 = (tte->depth() < replace->depth() ?  1 : 0);
 
       if (c1 + c2 + c3 > 0)