From: Marco Costalba Date: Wed, 2 Jun 2010 12:32:31 +0000 (+0100) Subject: Use SearchStack to pass allowNullmove X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=c51e12200a70ba91433181819ac5321f55c49f70 Use SearchStack to pass allowNullmove Also renamed allowNullmove in skipNullMove to reverse the logic so that the field is initialized to 0 (false) instead of 1 (true). No functional change also with faked split. Signed-off-by: Marco Costalba --- diff --git a/src/search.cpp b/src/search.cpp index 14063e0e..7f885f7a 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -285,7 +285,7 @@ namespace { Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, bool allowNullmove, int threadID); + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID); template Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID); @@ -876,7 +876,7 @@ namespace { alpha = -VALUE_INFINITE; // Full depth PV search, done on first move or after a fail high - value = -search(pos, ss+1, -beta, -alpha, newDepth, false, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, 0); } else { @@ -893,7 +893,7 @@ namespace { if (ss->reduction) { // Reduced depth non-pv search using alpha as upperbound - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 0); doFullDepthSearch = (value > alpha); } } @@ -903,12 +903,12 @@ namespace { { // Full depth non-pv search using alpha as upperbound ss->reduction = Depth(0); - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, true, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, 0); // If we are above alpha then research at same depth but as PV // to get a correct score or eventually a fail high above beta. if (value > alpha) - value = -search(pos, ss+1, -beta, -alpha, newDepth, false, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, 0); } } @@ -1031,8 +1031,7 @@ namespace { // search<>() is the main search function for both PV and non-PV nodes template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, - bool allowNullmove, int threadID) { + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); @@ -1060,6 +1059,7 @@ namespace { TM.incrementNodeCounter(threadID); ss->init(ply); (ss + 1)->excludedMove = MOVE_NONE; + (ss + 1)->skipNullMove = false; (ss + 2)->initKillers(); if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) @@ -1147,7 +1147,7 @@ namespace { // We're betting that the opponent doesn't have a move that will reduce // the score by more than futility_margin(depth) if we do a null move. if ( !PvNode - && allowNullmove + && !ss->skipNullMove && depth < RazorDepth && refinedValue >= beta + futility_margin(depth, 0) && !isCheck @@ -1160,7 +1160,7 @@ namespace { // at least beta. Otherwise we do a null move if static value is not more than // NullMoveMargin under beta. if ( !PvNode - && allowNullmove + && !ss->skipNullMove && depth > OnePly && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0) && !isCheck @@ -1178,8 +1178,13 @@ namespace { pos.do_null_move(st); + (ss+1)->skipNullMove = true; + nullValue = depth-R*OnePly < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly, false, threadID); + : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly, threadID); + + (ss+1)->skipNullMove = false; + pos.undo_null_move(); if (nullValue >= beta) @@ -1189,8 +1194,14 @@ namespace { nullValue = beta; // Do zugzwang verification search at high depths - if ( depth < 6 * OnePly - || search(pos, ss, alpha, beta, depth-5*OnePly, false, threadID) >= beta) + if (depth < 6 * OnePly) + return nullValue; + + ss->skipNullMove = true; + Value v = search(pos, ss, alpha, beta, depth-5*OnePly, threadID); + ss->skipNullMove = false; + + if (v >= beta) return nullValue; } else @@ -1218,7 +1229,11 @@ namespace { && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin))) { Depth d = (PvNode ? depth - 2 * OnePly : depth / 2); - search(pos, ss, alpha, beta, d, false, threadID); + + ss->skipNullMove = true; + search(pos, ss, alpha, beta, d, threadID); + ss->skipNullMove = false; + ttMove = ss->pv[ply]; tte = TT.retrieve(posKey); } @@ -1267,7 +1282,9 @@ namespace { { Value b = ttValue - SingularExtensionMargin; ss->excludedMove = move; - Value v = search(pos, ss, b - 1, b, depth / 2, false, threadID); + ss->skipNullMove = true; + Value v = search(pos, ss, b - 1, b, depth / 2, threadID); + ss->skipNullMove = false; ss->excludedMove = MOVE_NONE; if (v < ttValue - SingularExtensionMargin) @@ -1316,7 +1333,7 @@ namespace { // The first move in list is the expected PV if (PvNode && moveCount == 1) value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, newDepth, false, threadID); + : - search(pos, ss+1, -beta, -alpha, newDepth, threadID); else { // Step 14. Reduced depth search @@ -1334,7 +1351,7 @@ namespace { { Depth d = newDepth - ss->reduction; value = d < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) - : - search(pos, ss+1, -(alpha+1), -alpha, d, true, threadID); + : - search(pos, ss+1, -(alpha+1), -alpha, d, threadID); doFullDepthSearch = (value > alpha); } @@ -1347,7 +1364,7 @@ namespace { assert(newDepth - OnePly >= OnePly); ss->reduction = OnePly; - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, threadID); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, threadID); doFullDepthSearch = (value > alpha); } ss->reduction = Depth(0); // Restore original reduction @@ -1357,14 +1374,14 @@ namespace { if (doFullDepthSearch) { value = newDepth < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) - : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, true, threadID); + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, threadID); // Step extra. pv search (only in PV nodes) // Search only for possible new PV nodes, if instead value >= beta then // parent node fails low with value <= alpha and tries another move. if (PvNode && value > alpha && value < beta) value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, newDepth, false, threadID); + : - search(pos, ss+1, -beta, -alpha, newDepth, threadID); } } @@ -1725,7 +1742,7 @@ namespace { Value localAlpha = sp->alpha; Depth d = newDepth - ss->reduction; value = d < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID) - : - search(pos, ss+1, -(localAlpha+1), -localAlpha, d, true, threadID); + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, d, threadID); doFullDepthSearch = (value > localAlpha); } @@ -1738,7 +1755,7 @@ namespace { ss->reduction = OnePly; Value localAlpha = sp->alpha; - value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID); + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, threadID); doFullDepthSearch = (value > localAlpha); } ss->reduction = Depth(0); // Restore original reduction @@ -1749,14 +1766,14 @@ namespace { { Value localAlpha = sp->alpha; value = newDepth < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID) - : - search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, true, threadID); + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, threadID); // Step extra. pv search (only in PV nodes) // Search only for possible new PV nodes, if instead value >= beta then // parent node fails low with value <= alpha and tries another move. if (PvNode && value > localAlpha && value < sp->beta) value = newDepth < OnePly ? -qsearch(pos, ss+1, -sp->beta, -sp->alpha, Depth(0), threadID) - : - search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, false, threadID); + : - search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, threadID); } // Step 16. Undo move @@ -2227,6 +2244,7 @@ namespace { ss->init(i); ss->initKillers(); ss->excludedMove = MOVE_NONE; + ss->skipNullMove = false; } } diff --git a/src/search.h b/src/search.h index 73a1dcf0..6e91159d 100644 --- a/src/search.h +++ b/src/search.h @@ -58,6 +58,7 @@ struct SearchStack { Move killers[KILLER_MAX]; Depth reduction; Value eval; + bool skipNullMove; void init(int ply); void initKillers();