X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=cc8abc9ee814e48ccb1abca96d2e205921946ff9;hp=fe9b446e42d61b15b98212b3d05fa237e0701543;hb=3302349662f8c0b01946cd9d62ac087685c0c816;hpb=eb6d7f537d214c4dc8bde7d4fdc2aaead47dd3c3 diff --git a/src/search.cpp b/src/search.cpp index fe9b446e..cc8abc9e 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -227,10 +227,9 @@ void MainThread::search() { // Threads.stop. However, if we are pondering or in an infinite search, // the UCI protocol states that we shouldn't print the best move before the // GUI sends a "stop" or "ponderhit" command. We therefore simply wait here - // until the GUI sends one of those commands (which also raises Threads.stop). - Threads.stopOnPonderhit = true; + // until the GUI sends one of those commands. - while (!Threads.stop && (Threads.ponder || Limits.infinite)) + while (!Threads.stop && (ponder || Limits.infinite)) {} // Busy wait for a stop or a ponder reset // Stop the threads if not already stopped (also raise the stop if @@ -448,7 +447,7 @@ void Thread::search() { { failedHighCnt = 0; failedLow = true; - Threads.stopOnPonderhit = false; + mainThread->stopOnPonderhit = false; } } else if (bestValue >= beta) @@ -497,16 +496,13 @@ void Thread::search() { // Do we have time for the next iteration? Can we stop searching now? if ( Limits.use_time_management() && !Threads.stop - && !Threads.stopOnPonderhit) + && !mainThread->stopOnPonderhit) { double fallingEval = (306 + 119 * failedLow + 6 * (mainThread->previousScore - bestValue)) / 581.0; fallingEval = std::max(0.5, std::min(1.5, fallingEval)); // If the bestMove is stable over several iterations, reduce time accordingly - timeReduction = 1.0; - for (int i : {3, 4, 5}) - if (lastBestMoveDepth * i < completedDepth) - timeReduction *= 1.25; + timeReduction = lastBestMoveDepth + 10 * ONE_PLY < completedDepth ? 1.95 : 1.0; // Use part of the gained time from a previous stable move for the current move double bestMoveInstability = 1.0 + mainThread->bestMoveChanges; @@ -518,8 +514,8 @@ void Thread::search() { { // If we are allowed to ponder do not stop the search now but // keep pondering until the GUI sends "ponderhit" or "stop". - if (Threads.ponder) - Threads.stopOnPonderhit = true; + if (mainThread->ponder) + mainThread->stopOnPonderhit = true; else Threads.stop = true; } @@ -577,8 +573,8 @@ namespace { Move ttMove, move, excludedMove, bestMove; Depth extension, newDepth; Value bestValue, value, ttValue, eval, maxValue, pureStaticEval; - bool ttHit, inCheck, givesCheck, improving; - bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture, pvExact; + bool ttHit, pvHit, inCheck, givesCheck, improving; + bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture; Piece movedPiece; int moveCount, captureCount, quietCount; @@ -643,6 +639,7 @@ namespace { ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0] : ttHit ? tte->move() : MOVE_NONE; + pvHit = (ttHit && tte->pv_hit()) || (PvNode && depth > 4 * ONE_PLY); // At non-PV nodes we check for an early TT cutoff if ( !PvNode @@ -709,7 +706,7 @@ namespace { if ( b == BOUND_EXACT || (b == BOUND_LOWER ? value >= beta : value <= alpha)) { - tte->save(posKey, value_to_tt(value, ss->ply), b, + tte->save(posKey, value_to_tt(value, ss->ply), pvHit, b, std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), MOVE_NONE, VALUE_NONE); @@ -760,7 +757,7 @@ namespace { else ss->staticEval = eval = pureStaticEval = -(ss-1)->staticEval + 2 * Eval::Tempo; - tte->save(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, pureStaticEval); + tte->save(posKey, VALUE_NONE, pvHit, BOUND_NONE, DEPTH_NONE, MOVE_NONE, pureStaticEval); } // Step 7. Razoring (~2 Elo) @@ -891,7 +888,6 @@ moves_loop: // When in check, search starts from here skipQuiets = false; ttCapture = ttMove && pos.capture_or_promotion(ttMove); - pvExact = PvNode && ttHit && tte->bound() == BOUND_EXACT; // Step 12. Loop through all pseudo-legal moves until no moves remain // or a beta cutoff occurs. @@ -943,13 +939,21 @@ moves_loop: // When in check, search starts from here && tte->depth() >= depth - 3 * ONE_PLY && pos.legal(move)) { - Value reducedBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE); + Value singularBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE); ss->excludedMove = move; - value = search(pos, ss, reducedBeta - 1, reducedBeta, depth / 2, cutNode); + value = search(pos, ss, singularBeta - 1, singularBeta, depth / 2, cutNode); ss->excludedMove = MOVE_NONE; - if (value < reducedBeta) + if (value < singularBeta) extension = ONE_PLY; + + // Multi-cut pruning + // Our ttMove is assumed to fail high, and now we failed high also on a reduced + // search without the ttMove. So we assume this expected Cut-node is not singular, + // that is multiple moves fail high, and we can prune the whole subtree by returning + // the hard beta bound. + else if (cutNode && singularBeta > beta) + return beta; } else if ( givesCheck // Check extension (~2 Elo) && pos.see_ge(move)) @@ -1027,16 +1031,16 @@ moves_loop: // When in check, search starts from here { Depth r = reduction(improving, depth, moveCount); + // Decrease reduction if position is or has been on the PV + if (pvHit) + r -= ONE_PLY; + // Decrease reduction if opponent's move count is high (~10 Elo) if ((ss-1)->moveCount > 15) r -= ONE_PLY; if (!captureOrPromotion) { - // Decrease reduction for exact PV nodes (~0 Elo) - if (pvExact) - r -= ONE_PLY; - // Increase reduction if ttMove is a capture (~0 Elo) if (ttCapture) r += ONE_PLY; @@ -1209,7 +1213,7 @@ moves_loop: // When in check, search starts from here bestValue = std::min(bestValue, maxValue); if (!excludedMove) - tte->save(posKey, value_to_tt(bestValue, ss->ply), + tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit, bestValue >= beta ? BOUND_LOWER : PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, depth, bestMove, pureStaticEval); @@ -1239,7 +1243,7 @@ moves_loop: // When in check, search starts from here Move ttMove, move, bestMove; Depth ttDepth; Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; - bool ttHit, inCheck, givesCheck, evasionPrunable; + bool ttHit, pvHit, inCheck, givesCheck, evasionPrunable; int moveCount; if (PvNode) @@ -1273,6 +1277,7 @@ moves_loop: // When in check, search starts from here tte = TT.probe(posKey, ttHit); ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; ttMove = ttHit ? tte->move() : MOVE_NONE; + pvHit = ttHit && tte->pv_hit(); if ( !PvNode && ttHit @@ -1310,7 +1315,7 @@ moves_loop: // When in check, search starts from here if (bestValue >= beta) { if (!ttHit) - tte->save(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, + tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit, BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->staticEval); return bestValue; @@ -1421,7 +1426,7 @@ moves_loop: // When in check, search starts from here if (inCheck && bestValue == -VALUE_INFINITE) return mated_in(ss->ply); // Plies to mate from the root - tte->save(posKey, value_to_tt(bestValue, ss->ply), + tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit, bestValue >= beta ? BOUND_LOWER : PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, ttDepth, bestMove, ss->staticEval); @@ -1588,10 +1593,10 @@ void MainThread::check_time() { } // We should not stop pondering until told so by the GUI - if (Threads.ponder) + if (ponder) return; - if ( (Limits.use_time_management() && elapsed > Time.maximum() - 10) + if ( (Limits.use_time_management() && (elapsed > Time.maximum() - 10 || stopOnPonderhit)) || (Limits.movetime && elapsed >= Limits.movetime) || (Limits.nodes && Threads.nodes_searched() >= (uint64_t)Limits.nodes)) Threads.stop = true;