Move best = MOVE_NONE;
};
+ struct FastMove {
+ FastMove() { clear(); }
+
+ inline void clear() {
+ expectedPosKey = 0;
+ pv3[0] = pv3[1] = pv3[2] = MOVE_NONE;
+ stableCnt = 0;
+ }
+
+ void update(Position& pos) {
+ // Keep track how many times in a row the PV stays stable 3 ply deep.
+ const std::vector<Move>& RMpv = RootMoves[0].pv;
+ if (RMpv.size() >= 3)
+ {
+ if (pv3[2] == RMpv[2])
+ stableCnt++;
+ else
+ stableCnt = 0, pv3[2] = RMpv[2];
+
+ if (!expectedPosKey || pv3[0] != RMpv[0] || pv3[1] != RMpv[1])
+ {
+ pv3[0] = RMpv[0], pv3[1] = RMpv[1];
+ StateInfo st[2];
+ pos.do_move(RMpv[0], st[0], pos.gives_check(RMpv[0], CheckInfo(pos)));
+ pos.do_move(RMpv[1], st[1], pos.gives_check(RMpv[1], CheckInfo(pos)));
+ expectedPosKey = pos.key();
+ pos.undo_move(RMpv[1]);
+ pos.undo_move(RMpv[0]);
+ }
+ }
+ else
+ clear();
+ }
+
+ Key expectedPosKey;
+ Move pv3[3];
+ int stableCnt;
+ } FM;
+
size_t PVIdx;
TimeManager TimeMgr;
double BestMoveChanges;
Depth depth;
Value bestValue, alpha, beta, delta;
+ // Init fastMove if the previous search generated a candidate and we now got the predicted position.
+ const Move fastMove = (FM.expectedPosKey == pos.key()) ? FM.pv3[2] : MOVE_NONE;
+ FM.clear();
+
std::memset(ss-2, 0, 5 * sizeof(Stack));
depth = DEPTH_ZERO;
Signals.stop = true;
// Do we have time for the next iteration? Can we stop searching now?
- if (Limits.use_time_management() && !Signals.stop && !Signals.stopOnPonderhit)
+ if (Limits.use_time_management())
{
- // Take some extra time if the best move has changed
- if (depth > 4 * ONE_PLY && multiPV == 1)
- TimeMgr.pv_instability(BestMoveChanges);
-
- // Stop the search if only one legal move is available or all
- // of the available time has been used.
- if ( RootMoves.size() == 1
- || now() - SearchTime > TimeMgr.available_time())
+ if (!Signals.stop && !Signals.stopOnPonderhit)
{
- // If we are allowed to ponder do not stop the search now but
- // keep pondering until the GUI sends "ponderhit" or "stop".
- if (Limits.ponder)
- Signals.stopOnPonderhit = true;
- else
- Signals.stop = true;
+ // Take some extra time if the best move has changed
+ if (depth > 4 * ONE_PLY && multiPV == 1)
+ TimeMgr.pv_instability(BestMoveChanges);
+
+ // Stop the search if only one legal move is available or all
+ // of the available time has been used or we matched a fastMove
+ // from the previous search and just did a fast verification.
+ if ( RootMoves.size() == 1
+ || now() - SearchTime > TimeMgr.available_time()
+ || ( fastMove == RootMoves[0].pv[0]
+ && BestMoveChanges < 0.03
+ && 10 * (now() - SearchTime) > TimeMgr.available_time()))
+ {
+ // If we are allowed to ponder do not stop the search now but
+ // keep pondering until the GUI sends "ponderhit" or "stop".
+ if (Limits.ponder)
+ Signals.stopOnPonderhit = true;
+ else
+ Signals.stop = true;
+ }
}
+
+ // Update fast move stats.
+ FM.update(pos);
}
}
+ // Clear any candidate fast move that wasn't completely stable for at least
+ // the 6 final search iterations. (Independent of actual depth and thus TC.)
+ // Time condition prevents consecutive fast moves.
+ if (FM.stableCnt < 6 || now() - SearchTime < TimeMgr.available_time())
+ FM.clear();
+
// If skill level is enabled, swap best PV line with the sub-optimal one
if (skill.enabled())
std::swap(RootMoves[0], *std::find(RootMoves.begin(),
if (value > alpha)
{
+ // Clear fast move if unstable.
+ if (PvNode && pos.key() == FM.expectedPosKey && (move != FM.pv3[2] || moveCount > 1))
+ FM.clear();
+
bestMove = SpNode ? splitPoint->bestMove = move : move;
if (PvNode && !RootNode) // Update pv even in fail-high case