X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=768a22a4d36b50ce919248e7c0dc4cc95fe286c8;hp=72bf6e8191db420163a6b32b8aa4f941fd4adcd6;hb=2feb9d5100038038b371c91562bbf5342a815c39;hpb=725c504a5fcb4cd516f2ce0d1da29058548d070c diff --git a/src/search.cpp b/src/search.cpp index 72bf6e81..768a22a4 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -133,9 +133,6 @@ namespace { // when the static evaluation is at most IIDMargin below beta. const Value IIDMargin = Value(0x100); - // Use easy moves? - const bool UseEasyMove = true; - // Easy move margin. An easy move candidate must be at least this much // better than the second best move. const Value EasyMoveMargin = Value(0x200); @@ -169,7 +166,7 @@ namespace { // nodes, and at pre-frontier nodes Value FutilityMargin0 = Value(0x80); Value FutilityMargin1 = Value(0x100); - Value FutilityMargin2 = Value(0x300); + Value FutilityMargin2 = Value(0x200); // Razoring Depth RazorDepth = 4*OnePly; @@ -940,16 +937,17 @@ namespace { assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); - // Initialize, and make an early exit in case of an aborted search, - // an instant draw, maximum ply reached, etc. - if (AbortSearch || thread_should_stop(threadID)) - return Value(0); - if (depth < OnePly) return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID); + // Initialize, and make an early exit in case of an aborted search, + // an instant draw, maximum ply reached, etc. init_node(pos, ss, ply, threadID); + // After init_node() that calls poll() + if (AbortSearch || thread_should_stop(threadID)) + return Value(0); + if (pos.is_draw()) return VALUE_DRAW; @@ -1003,9 +1001,8 @@ namespace { movesSearched[moveCount++] = ss[ply].currentMove = move; if (moveIsCapture) - ss[ply].currentMoveCaptureValue = pos.midgame_value_of_piece_on(move_to(move)); - else if (move_is_ep(move)) - ss[ply].currentMoveCaptureValue = PawnValueMidgame; + ss[ply].currentMoveCaptureValue = + move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); else ss[ply].currentMoveCaptureValue = Value(0); @@ -1038,7 +1035,7 @@ namespace { else value = alpha + 1; // Just to trigger next condition - if (value > alpha) // Go with full depth pv search + if (value > alpha) // Go with full depth non-pv search { ss[ply].reduction = Depth(0); value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); @@ -1076,7 +1073,9 @@ namespace { // If we are at ply 1, and we are searching the first root move at // ply 0, set the 'Problem' variable if the score has dropped a lot // (from the computer's point of view) since the previous iteration: - if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin) + if ( ply == 1 + && Iteration >= 2 + && -value <= ValueByIteration[Iteration-1] - ProblemMargin) Problem = true; } @@ -1133,21 +1132,22 @@ namespace { assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); - EvalInfo ei; + if (depth < OnePly) + return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); // Initialize, and make an early exit in case of an aborted search, // an instant draw, maximum ply reached, etc. + init_node(pos, ss, ply, threadID); + + // After init_node() that calls poll() if (AbortSearch || thread_should_stop(threadID)) return Value(0); - if (depth < OnePly) - return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - - init_node(pos, ss, ply, threadID); - if (pos.is_draw()) return VALUE_DRAW; + EvalInfo ei; + if (ply >= PLY_MAX - 1) return evaluate(pos, ei, threadID); @@ -1190,8 +1190,8 @@ namespace { Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); // Check for a null capture artifact, if the value without the null capture - // is above beta then there is a good possibility that this is a cut-node. - // We will do an IID later to find a ttMove. + // is above beta then mark the node as a suspicious failed low. We will verify + // later if we are really under threat. if ( UseNullDrivenIID && nullValue < beta && depth > 6 * OnePly @@ -1237,13 +1237,12 @@ namespace { } } // Null move search not allowed, try razoring - else if ( !isCheck - && !value_is_mate(beta) - && ( (approximateEval < beta - RazorMargin && depth < RazorDepth) - ||(approximateEval < beta - PawnValueMidgame && depth <= OnePly))) + else if ( !value_is_mate(beta) + && approximateEval < beta - RazorMargin + && depth < RazorDepth) { Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - if (v < beta) + if (v < beta - RazorMargin / 2) return v; } @@ -1258,7 +1257,9 @@ namespace { { // The null move failed low due to a suspicious capture. Perhaps we // are facing a null capture artifact due to the side to move change - // and this is a cut-node. So it's a good time to search for a ttMove. + // and this position should fail high. So do a normal search with a + // reduced depth to get a good ttMove to use in the following full + // depth search. Move tm = ss[ply].threatMove; assert(tm != MOVE_NONE); @@ -1307,17 +1308,19 @@ namespace { && !moveIsCapture && !move_promotion(move)) { - // History pruning. See ok_to_prune() definition. + // History pruning. See ok_to_prune() definition if ( moveCount >= 2 + int(depth) && ok_to_prune(pos, move, ss[ply].threatMove, depth)) continue; - // Value based pruning. - if (depth < 3 * OnePly && approximateEval < beta) + // Value based pruning + if (depth < 7 * OnePly && approximateEval < beta) { if (futilityValue == VALUE_NONE) futilityValue = evaluate(pos, ei, threadID) - + (depth < 2 * OnePly ? FutilityMargin1 : FutilityMargin2); + + (depth < 2 * OnePly ? FutilityMargin1 : + + (depth < 6 * OnePly ? FutilityMargin2 + (depth - 2*OnePly) * 32 + : FutilityMargin2 + (depth - 2*OnePly) * 64)); if (futilityValue < beta) { @@ -1421,15 +1424,14 @@ namespace { assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); - EvalInfo ei; - // Initialize, and make an early exit in case of an aborted search, // an instant draw, maximum ply reached, etc. + init_node(pos, ss, ply, threadID); + + // After init_node() that calls poll() if (AbortSearch || thread_should_stop(threadID)) return Value(0); - init_node(pos, ss, ply, threadID); - if (pos.is_draw()) return VALUE_DRAW; @@ -1439,6 +1441,7 @@ namespace { return value_from_tt(tte->value(), ply); // Evaluate the position statically + EvalInfo ei; bool isCheck = pos.is_check(); Value staticValue = (isCheck ? -VALUE_INFINITE : evaluate(pos, ei, threadID)); @@ -1691,8 +1694,11 @@ namespace { assert(move_is_ok(move)); - ss[sp->ply].currentMoveCaptureValue = move_is_ep(move)? - PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); + if (moveIsCapture) + ss[sp->ply].currentMoveCaptureValue = + move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); + else + ss[sp->ply].currentMoveCaptureValue = Value(0); lock_grab(&(sp->lock)); int moveCount = ++sp->moves; @@ -1773,8 +1779,10 @@ namespace { } // If we are at ply 1, and we are searching the first root move at // ply 0, set the 'Problem' variable if the score has dropped a lot - // (from the computer's point of view) since the previous iteration: - if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin) + // (from the computer's point of view) since the previous iteration. + if ( sp->ply == 1 + && Iteration >= 2 + && -value <= ValueByIteration[Iteration-1] - ProblemMargin) Problem = true; } lock_release(&(sp->lock)); @@ -1783,7 +1791,7 @@ namespace { lock_grab(&(sp->lock)); // If this is the master thread and we have been asked to stop because of - // a beta cutoff higher up in the tree, stop all slave threads: + // a beta cutoff higher up in the tree, stop all slave threads. if (sp->master == threadID && thread_should_stop(threadID)) for (int i = 0; i < ActiveThreads; i++) if (sp->slaves[i]) @@ -2168,6 +2176,8 @@ namespace { Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat, bool* dangerous) { + assert(m != MOVE_NONE); + Depth result = Depth(0); *dangerous = check || singleReply || mateThreat; @@ -2191,10 +2201,12 @@ namespace { *dangerous = true; } - if ( pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame + if ( pos.move_is_capture(m) + && pos.type_of_piece_on(move_to(m)) != PAWN && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - pos.midgame_value_of_piece_on(move_to(m)) == Value(0)) - && !move_promotion(m)) + && !move_promotion(m) + && !move_is_ep(m)) { result += PawnEndgameExtension[pvNode]; *dangerous = true; @@ -2260,7 +2272,7 @@ namespace { // value of the threatening piece, don't prune move which defend it. if ( !PruneDefendingMoves && threat != MOVE_NONE - && pos.type_of_piece_on(tto) != NO_PIECE_TYPE + && pos.move_is_capture(threat) && ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto) || pos.type_of_piece_on(tfrom) == KING) && pos.move_attacks_square(m, tto)) @@ -2275,7 +2287,8 @@ namespace { if ( !PruneBlockingMoves && threat != MOVE_NONE && piece_is_slider(pos.piece_on(tfrom)) - && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0) + && bit_is_set(squares_between(tfrom, tto), mto) + && pos.see(m) >= 0) return false; return true;