Introduce static history

The idea of this patch can be described as following: we update static history stats based on comparison of the static evaluations of the position before and after the move. If the move increases static evaluation it's assigned positive bonus, if it decreases static evaluation it's assigned negative bonus. These stats are used in movepicker to sort quiet moves. passed STC https://tests.stockfishchess.org/tests/view/5fca4c0842a050a89f02cd66 LLR: 3.00 (-2.94,2.94) {-0.25,1.25} Total: 78152 W: 7409 L: 7171 D: 63572 Ptnml(0-2): 303, 5695, 26873, 5871, 334 passed LTC https://tests.stockfishchess.org/tests/view/5fca6be442a050a89f02cd75 LLR: 2.94 (-2.94,2.94) {0.25,1.25} Total: 40240 W: 1602 L: 1441 D: 37197 Ptnml(0-2): 19, 1306, 17305, 1475, 15 closes official-stockfish/Stockfish#3253 bench 3845156
joergoster · Dec 19, 2020 · 57648e5 · 57648e5
1 parent 892fc2a
commit 57648e5
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Showing 5 changed files with 21 additions and 4 deletions.
diff --git a/src/movepick.cpp b/src/movepick.cpp
@@ -54,9 +54,9 @@ namespace {
 /// ordering is at the current node.
 
 /// MovePicker constructor for the main search
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const LowPlyHistory* lp,
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const ButterflyHistory* sh, const LowPlyHistory* lp,
                        const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, const Move* killers, int pl)
-           : pos(p), mainHistory(mh), lowPlyHistory(lp), captureHistory(cph), continuationHistory(ch),
+           : pos(p), mainHistory(mh), staticHistory(sh), lowPlyHistory(lp), captureHistory(cph), continuationHistory(ch),
              ttMove(ttm), refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, depth(d), ply(pl) {
 
   assert(d > 0);
@@ -66,9 +66,9 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHist
 }
 
 /// MovePicker constructor for quiescence search
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const ButterflyHistory* sh,
                        const CapturePieceToHistory* cph, const PieceToHistory** ch, Square rs)
-           : pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch), ttMove(ttm), recaptureSquare(rs), depth(d) {
+           : pos(p), mainHistory(mh), staticHistory(sh), captureHistory(cph), continuationHistory(ch), ttMove(ttm), recaptureSquare(rs), depth(d) {
 
   assert(d <= 0);
 
@@ -105,6 +105,7 @@ void MovePicker::score() {
 
       else if (Type == QUIETS)
           m.value =      (*mainHistory)[pos.side_to_move()][from_to(m)]
+                   +     (*staticHistory)[pos.side_to_move()][from_to(m)]
                    + 2 * (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
                    + 2 * (*continuationHistory[1])[pos.moved_piece(m)][to_sq(m)]
                    + 2 * (*continuationHistory[3])[pos.moved_piece(m)][to_sq(m)]

diff --git a/src/movepick.h b/src/movepick.h
@@ -123,10 +123,12 @@ class MovePicker {
   MovePicker& operator=(const MovePicker&) = delete;
   MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
   MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
+                                           const ButterflyHistory*,
                                            const CapturePieceToHistory*,
                                            const PieceToHistory**,
                                            Square);
   MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
+                                           const ButterflyHistory*,
                                            const LowPlyHistory*,
                                            const CapturePieceToHistory*,
                                            const PieceToHistory**,
@@ -143,6 +145,7 @@ class MovePicker {
 
   const Position& pos;
   const ButterflyHistory* mainHistory;
+  const ButterflyHistory* staticHistory;
   const LowPlyHistory* lowPlyHistory;
   const CapturePieceToHistory* captureHistory;
   const PieceToHistory** continuationHistory;

diff --git a/src/search.cpp b/src/search.cpp
@@ -791,6 +791,15 @@ namespace {
         tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
     }
 
+    // Update static history for previous move
+    if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture)
+    {
+        int bonus = ss->staticEval > -(ss-1)->staticEval + 2 * Tempo ? -stat_bonus(depth) :
+                    ss->staticEval < -(ss-1)->staticEval + 2 * Tempo ? stat_bonus(depth) :
+                    0;
+        thisThread->staticHistory[~us][from_to((ss-1)->currentMove)] << bonus;
+    }
+
     // Step 7. Razoring (~1 Elo)
     if (   !rootNode // The required rootNode PV handling is not available in qsearch
         &&  depth == 1
@@ -949,6 +958,7 @@ namespace {
     Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
 
     MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
+                                      &thisThread->staticHistory,
                                       &thisThread->lowPlyHistory,
                                       &captureHistory,
                                       contHist,
@@ -1490,6 +1500,7 @@ namespace {
     // queen and checking knight promotions, and other checks(only if depth >= DEPTH_QS_CHECKS)
     // will be generated.
     MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
+                                      &thisThread->staticHistory,
                                       &thisThread->captureHistory,
                                       contHist,
                                       to_sq((ss-1)->currentMove));

diff --git a/src/thread.cpp b/src/thread.cpp
@@ -57,6 +57,7 @@ void Thread::clear() {
 
   counterMoves.fill(MOVE_NONE);
   mainHistory.fill(0);
+  staticHistory.fill(0);
   lowPlyHistory.fill(0);
   captureHistory.fill(0);
 

diff --git a/src/thread.h b/src/thread.h
@@ -69,6 +69,7 @@ class Thread {
   Depth rootDepth, completedDepth;
   CounterMoveHistory counterMoves;
   ButterflyHistory mainHistory;
+  ButterflyHistory staticHistory;
   LowPlyHistory lowPlyHistory;
   CapturePieceToHistory captureHistory;
   ContinuationHistory continuationHistory[2][2];