Non-quiet pruning tweak

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 1279fe9c588b837ff1664fbe44d0b9c8459f4567..a74e3f256833c576c4e11f19462367af32f91119 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -113,8 +113,8 @@ namespace {
           std::copy(newPv.begin(), newPv.begin() + 3, pv);
 
           StateInfo st[2];
-          pos.do_move(newPv[0], st[0], pos.gives_check(newPv[0]));
-          pos.do_move(newPv[1], st[1], pos.gives_check(newPv[1]));
+          pos.do_move(newPv[0], st[0]);
+          pos.do_move(newPv[1], st[1]);
           expectedPosKey = pos.key();
           pos.undo_move(newPv[1]);
           pos.undo_move(newPv[0]);
@@ -234,7 +234,7 @@ uint64_t Search::perft(Position& pos, Depth depth) {
           cnt = 1, nodes++;
       else
       {
-          pos.do_move(m, st, pos.gives_check(m));
+          pos.do_move(m, st);
           cnt = leaf ? MoveList<LEGAL>(pos).size() : perft<false>(pos, depth - ONE_PLY);
           nodes += cnt;
           pos.undo_move(m);
@@ -335,12 +335,12 @@ void MainThread::search() {
 
 void Thread::search() {
 
-  Stack stack[MAX_PLY+7], *ss = stack+5; // To allow referencing (ss-5) and (ss+2)
+  Stack stack[MAX_PLY+7], *ss = stack+4; // To allow referencing (ss-4) and (ss+2)
   Value bestValue, alpha, beta, delta;
   Move easyMove = MOVE_NONE;
   MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
 
-  std::memset(ss-5, 0, 8 * sizeof(Stack));
+  std::memset(ss-4, 0, 7 * sizeof(Stack));
 
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
@@ -801,7 +801,7 @@ namespace {
             {
                 ss->currentMove = move;
                 ss->counterMoves = &thisThread->counterMoveHistory[pos.moved_piece(move)][to_sq(move)];
-                pos.do_move(move, st, pos.gives_check(move));
+                pos.do_move(move, st);
                 value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode);
                 pos.undo_move(move);
                 if (value >= rbeta)
@@ -944,10 +944,15 @@ moves_loop: // When in check search starts from here
                   && !pos.see_ge(move, Value(-35 * lmrDepth * lmrDepth)))
                   continue;
           }
-          else if (   depth < 7 * ONE_PLY
-                   && !extension
-                   && !pos.see_ge(move, Value(-35 * depth / ONE_PLY * depth / ONE_PLY)))
+          else if (depth < 7 * ONE_PLY && !extension)
+          {
+              Value v = Value(-35 * depth / ONE_PLY * depth / ONE_PLY);
+              if (ss->staticEval != VALUE_NONE)
+                  v += ss->staticEval - alpha - 200;
+
+              if (!pos.see_ge(move, v))
                   continue;
+          }
       }
 
       // Speculative prefetch as early as possible
@@ -984,8 +989,7 @@ moves_loop: // When in check search starts from here
 
               // Decrease reduction for moves that escape a capture. Filter out
               // castling moves, because they are coded as "king captures rook" and
-              // hence break make_move(). Also use see() instead of see_sign(),
-              // because the destination square is empty.
+              // hence break make_move().
               else if (   type_of(move) == NORMAL
                        && type_of(pos.piece_on(to_sq(move))) != PAWN
                        && !pos.see_ge(make_move(to_sq(move), from_sq(move)),  VALUE_ZERO))
@@ -1601,7 +1605,7 @@ bool RootMove::extract_ponder_from_tt(Position& pos) {
     if (!pv[0])
         return false;
 
-    pos.do_move(pv[0], st, pos.gives_check(pv[0]));
+    pos.do_move(pv[0], st);
     TTEntry* tte = TT.probe(pos.key(), ttHit);
 
     if (ttHit)