From 8d1625d6df6d9918ca85cd3e169a06e3749c2f67 Mon Sep 17 00:00:00 2001 From: Joost VandeVondele Date: Tue, 8 May 2018 10:43:46 +0200 Subject: [PATCH] Remove skipEarlyPruning argument to search() Remove nine boolean arguments and the corresponding skipEarlyPruning variable. Instead, skip early pruning only when there is an excluded move, and try null move pruning only if the previous move was not itself a null move. passed STC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 33623 W: 6853 L: 6755 D: 20015 http://tests.stockfishchess.org/tests/view/5aef462a0ebc5902a409a10e passed LTC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 39474 W: 5882 L: 5789 D: 27803 http://tests.stockfishchess.org/tests/view/5aefd4b80ebc5902a409a164 Closes https://github.com/official-stockfish/Stockfish/pull/1585 Bench: 4953556 --- src/search.cpp | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index 8a610571..2072c4bc 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -107,7 +107,7 @@ namespace { }; template - Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning); + Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode); template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = DEPTH_ZERO); @@ -390,7 +390,7 @@ void Thread::search() { // high/low anymore. while (true) { - bestValue = ::search(rootPos, ss, alpha, beta, rootDepth, false, false); + bestValue = ::search(rootPos, ss, alpha, beta, rootDepth, false); // Bring the best move to the front. It is critical that sorting // is done with a stable algorithm because all the values but the @@ -517,7 +517,7 @@ namespace { // search<>() is the main search function for both PV and non-PV nodes template - Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning) { + Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) { // Use quiescence search when needed if (depth < ONE_PLY) @@ -713,7 +713,7 @@ namespace { improving = ss->staticEval >= (ss-2)->staticEval ||(ss-2)->staticEval == VALUE_NONE; - if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move())) + if (ss->excludedMove || !pos.non_pawn_material(pos.side_to_move())) goto moves_loop; // Step 7. Razoring (skipped when in check, ~2 Elo) @@ -736,6 +736,7 @@ namespace { // Step 9. Null move search with verification search (~40 Elo) if ( !PvNode + && (ss-1)->currentMove != MOVE_NULL && eval >= beta && ss->staticEval >= beta - 36 * depth / ONE_PLY + 225 && (ss->ply >= thisThread->nmp_ply || ss->ply % 2 != thisThread->nmp_odd)) @@ -750,7 +751,7 @@ namespace { pos.do_null_move(st); - Value nullValue = -search(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true); + Value nullValue = -search(pos, ss+1, -beta, -beta+1, depth-R, !cutNode); pos.undo_null_move(); @@ -768,7 +769,7 @@ namespace { thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4; thisThread->nmp_odd = ss->ply % 2; - Value v = search(pos, ss, beta-1, beta, depth-R, false, true); + Value v = search(pos, ss, beta-1, beta, depth-R, false); thisThread->nmp_odd = thisThread->nmp_ply = 0; @@ -784,8 +785,6 @@ namespace { && depth >= 5 * ONE_PLY && abs(beta) < VALUE_MATE_IN_MAX_PLY) { - assert(is_ok((ss-1)->currentMove)); - Value rbeta = std::min(beta + 216 - 48 * improving, VALUE_INFINITE); MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory); int probCutCount = 0; @@ -808,7 +807,7 @@ namespace { // If the qsearch held perform the regular search if (value >= rbeta) - value = -search(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false); + value = -search(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode); pos.undo_move(move); @@ -822,7 +821,7 @@ namespace { && !ttMove) { Depth d = 3 * depth / 4 - 2 * ONE_PLY; - search(pos, ss, alpha, beta, d, cutNode, true); + search(pos, ss, alpha, beta, d, cutNode); tte = TT.probe(posKey, ttHit); ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; @@ -897,7 +896,7 @@ moves_loop: // When in check, search starts from here { Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE); ss->excludedMove = move; - value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode, true); + value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode); ss->excludedMove = MOVE_NONE; if (value < rBeta) @@ -1027,7 +1026,7 @@ moves_loop: // When in check, search starts from here Depth d = std::max(newDepth - r, ONE_PLY); - value = -search(pos, ss+1, -(alpha+1), -alpha, d, true, false); + value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); doFullDepthSearch = (value > alpha && d != newDepth); } @@ -1036,7 +1035,7 @@ moves_loop: // When in check, search starts from here // Step 17. Full depth search when LMR is skipped or fails high if (doFullDepthSearch) - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); // For PV nodes only, do a full PV search on the first move or after a fail // high (in the latter case search only if value < beta), otherwise let the @@ -1046,7 +1045,7 @@ moves_loop: // When in check, search starts from here (ss+1)->pv = pv; (ss+1)->pv[0] = MOVE_NONE; - value = -search(pos, ss+1, -beta, -alpha, newDepth, false, false); + value = -search(pos, ss+1, -beta, -alpha, newDepth, false); } // Step 18. Undo move -- 2.39.2