Simplify verification search (#1362)

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 66c432fc823c51bc7e780c18c4cc3119055a0499..2fd842070cfe2720217eb6f8876aa02ba61075a7 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -676,7 +676,7 @@ namespace {
     if (   !PvNode
         &&  eval >= beta
         &&  ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
-               && (ss->ply >= thisThread->nmp_ply || ss->ply % 2 == thisThread->pair))
+        && (ss->ply >= thisThread->nmp_ply || ss->ply % 2 != thisThread->nmp_odd))
     {
 
         assert(eval - beta >= 0);
@@ -698,21 +698,18 @@ namespace {
             if (nullValue >= VALUE_MATE_IN_MAX_PLY)
                 nullValue = beta;
 
-            if (depth < 12 * ONE_PLY && abs(beta) < VALUE_KNOWN_WIN)
+            if (abs(beta) < VALUE_KNOWN_WIN && (depth < 12 * ONE_PLY || thisThread->nmp_ply))
                 return nullValue;
 
             // Do verification search at high depths
-            R += ONE_PLY;
             // disable null move pruning for side to move for the first part of the remaining search tree
-            int nmp_ply = thisThread->nmp_ply;
-            int pair = thisThread->pair;
             thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4;
-            thisThread->pair = (ss->ply % 2) == 0;
+            thisThread->nmp_odd = ss->ply % 2;
 
             Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, beta-1, beta)
                                         :  search<NonPV>(pos, ss, beta-1, beta, depth-R, false, true);
-            thisThread->pair = pair;
-            thisThread->nmp_ply = nmp_ply;
+
+            thisThread->nmp_odd = thisThread->nmp_ply = 0;
 
             if (v >= beta)
                 return nullValue;
@@ -1497,7 +1494,7 @@ moves_loop: // When in check search starts from here
     if (Threads.ponder)
         return;
 
-    if (   (Limits.use_time_management() && elapsed > Time.maximum())
+    if (   (Limits.use_time_management() && elapsed > Time.maximum() - 10)
         || (Limits.movetime && elapsed >= Limits.movetime)
         || (Limits.nodes && Threads.nodes_searched() >= (uint64_t)Limits.nodes))
             Threads.stop = true;