From 42d9b4a868b065bf6f5e4ff2e81ca3f751999886 Mon Sep 17 00:00:00 2001
From: Matthies <a.matthies@online.de>
Date: Wed, 7 Jul 2021 17:14:31 +0200
Subject: [PATCH] Avoid empty move list in last pv when using multiple threads.

---
 src/search.cpp | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/search.cpp b/src/search.cpp
index 883f2809..5e010a05 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1356,15 +1356,19 @@ static void search_gen1(searchthread *thr)
             }
         }
 
-        // copy new pv to lastpv
-        int i = 0;
-        while (pos->pvtable[0][i])
+        int i;
+        if (pos->pvtable[0][0])
         {
-            pos->lastpv[i] = pos->pvtable[0][i];
-            i++;
-            if (i == MAXDEPTH - 1) break;
+            // copy new pv to lastpv
+            i = 0;
+            while (pos->pvtable[0][i])
+            {
+                pos->lastpv[i] = pos->pvtable[0][i];
+                i++;
+                if (i == MAXDEPTH - 1) break;
+            }
+            pos->lastpv[i] = 0;
         }
-        pos->lastpv[i] = 0;
 
         nowtime = getTime();