Remove 'update gains' hack

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4ac4c086c00e18f29419c96df0696b3f2f23cfc0..1b11092aa3d527a5561245e45660cb66da7898ac 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -25,11 +25,11 @@
 #include <iostream>
 #include <sstream>
 
-#include "book.h"
 #include "evaluate.h"
 #include "movegen.h"
 #include "movepick.h"
 #include "notation.h"
+#include "rkiss.h"
 #include "search.h"
 #include "timeman.h"
 #include "thread.h"
@@ -42,7 +42,6 @@ namespace Search {
   LimitsType Limits;
   std::vector<RootMove> RootMoves;
   Position RootPos;
-  Color RootColor;
   Time::point SearchTime;
   StateStackPtr SetupStates;
 }
@@ -180,14 +179,11 @@ uint64_t Search::perft(Position& pos, Depth depth) {
 
 void Search::think() {
 
-  static PolyglotBook book; // Defined static to initialize the PRNG only once
-
-  RootColor = RootPos.side_to_move();
-  TimeMgr.init(Limits, RootPos.game_ply(), RootColor);
+  TimeMgr.init(Limits, RootPos.game_ply(), RootPos.side_to_move());
 
   int cf = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns
-  DrawValue[ RootColor] = VALUE_DRAW - Value(cf);
-  DrawValue[~RootColor] = VALUE_DRAW + Value(cf);
+  DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf);
+  DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(cf);
 
   if (RootMoves.empty())
   {
@@ -199,25 +195,14 @@ void Search::think() {
       goto finalize;
   }
 
-  if (Options["OwnBook"] && !Limits.infinite && !Limits.mate)
-  {
-      Move bookMove = book.probe(RootPos, Options["Book File"], Options["Best Book Move"]);
-
-      if (bookMove && std::count(RootMoves.begin(), RootMoves.end(), bookMove))
-      {
-          std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), bookMove));
-          goto finalize;
-      }
-  }
-
   if (Options["Write Search Log"])
   {
       Log log(Options["Search Log Filename"]);
       log << "\nSearching: "  << RootPos.fen()
           << "\ninfinite: "   << Limits.infinite
           << " ponder: "      << Limits.ponder
-          << " time: "        << Limits.time[RootColor]
-          << " increment: "   << Limits.inc[RootColor]
+          << " time: "        << Limits.time[RootPos.side_to_move()]
+          << " increment: "   << Limits.inc[RootPos.side_to_move()]
           << " moves to go: " << Limits.movestogo
           << "\n" << std::endl;
   }
@@ -285,7 +270,6 @@ namespace {
     Value bestValue, alpha, beta, delta;
 
     std::memset(ss-2, 0, 5 * sizeof(Stack));
-    (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
 
     depth = 0;
     BestMoveChanges = 0;
@@ -485,7 +469,7 @@ namespace {
     bestValue = -VALUE_INFINITE;
     ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
     ss->ply = (ss-1)->ply + 1;
-    (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
+    (ss+1)->skipNullMove = (ss+1)->nullChild = false; (ss+1)->reduction = DEPTH_ZERO;
     (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
 
     // Used to send selDepth info to GUI
@@ -560,7 +544,7 @@ namespace {
     }
     else
     {
-        eval = ss->staticEval = evaluate(pos);
+        eval = ss->staticEval = ss->nullChild ? -(ss-1)->staticEval + 2 * Eval::Tempo : evaluate(pos);
         TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->staticEval);
     }
 
@@ -568,6 +552,7 @@ namespace {
         &&  ss->staticEval != VALUE_NONE
         && (ss-1)->staticEval != VALUE_NONE
         && (move = (ss-1)->currentMove) != MOVE_NULL
+        &&  move != MOVE_NONE
         &&  type_of(move) == NORMAL)
     {
         Square to = to_sq(move);
@@ -620,10 +605,10 @@ namespace {
                  + int(eval - beta) / PawnValueMg * ONE_PLY;
 
         pos.do_null_move(st);
-        (ss+1)->skipNullMove = true;
+        (ss+1)->skipNullMove = (ss+1)->nullChild = true;
         nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1, DEPTH_ZERO)
                                       : - search<NonPV, false>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode);
-        (ss+1)->skipNullMove = false;
+        (ss+1)->skipNullMove = (ss+1)->nullChild = false;
         pos.undo_null_move();
 
         if (nullValue >= beta)
@@ -881,6 +866,13 @@ moves_loop: // When in check and at SpNode search starts from here
           if (move == countermoves[0] || move == countermoves[1])
               ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
 
+          // Decrease reduction for moves that escape a capture
+          if (   ss->reduction
+              && type_of(move) == NORMAL
+              && type_of(pos.piece_on(to_sq(move))) != PAWN
+              && pos.see(make_move(to_sq(move), from_sq(move))) < 0)
+              ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
+
           Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
           if (SpNode)
               alpha = splitPoint->alpha;
@@ -1116,7 +1108,7 @@ moves_loop: // When in check and at SpNode search starts from here
                     bestValue = ttValue;
         }
         else
-            ss->staticEval = bestValue = evaluate(pos);
+            ss->staticEval = bestValue = ss->nullChild ? -(ss-1)->staticEval + 2 * Eval::Tempo : evaluate(pos);
 
         // Stand pat. Return immediately if static value is at least beta
         if (bestValue >= beta)
@@ -1559,7 +1551,7 @@ void Thread::idle_loop() {
           if (Threads.size() > 2)
               for (size_t i = 0; i < Threads.size(); ++i)
               {
-                  int size = Threads[i]->splitPointsSize; // Local copy
+                  const int size = Threads[i]->splitPointsSize; // Local copy
                   sp = size ? &Threads[i]->splitPoints[size - 1] : NULL;
 
                   if (   sp