From 8ec97d161ed82b7c1d8f1f05c305e9a55d8ccff3 Mon Sep 17 00:00:00 2001 From: Unai Corzo Date: Sat, 26 Dec 2020 13:48:04 +0100 Subject: [PATCH] Remove razoring has become ineffective now. STC https://tests.stockfishchess.org/tests/view/5fe653403932f79192d3981a LLR: 2.95 (-2.94,2.94) {-1.25,0.25} Total: 63448 W: 5965 L: 5934 D: 51549 Ptnml(0-2): 230, 4738, 21769, 4745, 242 LTC https://tests.stockfishchess.org/tests/view/5fe6f0f03932f79192d39856 LLR: 2.93 (-2.94,2.94) {-0.75,0.25} Total: 65368 W: 2485 L: 2459 D: 60424 Ptnml(0-2): 33, 2186, 28230, 2192, 43 closes https://github.com/official-stockfish/Stockfish/pull/3278 bench: 4493379 --- src/search.cpp | 35 ++++++++++++++--------------------- 1 file changed, 14 insertions(+), 21 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index b96efad0..e2c3f584 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -62,8 +62,7 @@ namespace { constexpr uint64_t TtHitAverageWindow = 4096; constexpr uint64_t TtHitAverageResolution = 1024; - // Razor and futility margins - constexpr int RazorMargin = 510; + // Futility margin Value futility_margin(Depth d, bool improving) { return Value(234 * (d - improving)); } @@ -822,12 +821,6 @@ namespace { thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus; } - // Step 7. Razoring (~1 Elo) - if ( !rootNode // The required rootNode PV handling is not available in qsearch - && depth == 1 - && eval <= alpha - RazorMargin) - return qsearch(pos, ss, alpha, beta); - // Set up improving flag that is used in various pruning heuristics // We define position as improving if static evaluation of position is better // Than the previous static evaluation at our turn @@ -836,14 +829,14 @@ namespace { ? ss->staticEval > (ss-4)->staticEval || (ss-4)->staticEval == VALUE_NONE : ss->staticEval > (ss-2)->staticEval; - // Step 8. Futility pruning: child node (~50 Elo) + // Step 7. Futility pruning: child node (~50 Elo) if ( !PvNode && depth < 9 && eval - futility_margin(depth, improving) >= beta && eval < VALUE_KNOWN_WIN) // Do not return unproven wins return eval; - // Step 9. Null move search with verification search (~40 Elo) + // Step 8. Null move search with verification search (~40 Elo) if ( !PvNode && (ss-1)->currentMove != MOVE_NULL && (ss-1)->statScore < 22977 @@ -895,7 +888,7 @@ namespace { probCutBeta = beta + 194 - 49 * improving; - // Step 10. ProbCut (~10 Elo) + // Step 9. ProbCut (~10 Elo) // If we have a good enough capture and a reduced search returns a value // much above beta, we can (almost) safely prune the previous move. if ( !PvNode @@ -968,7 +961,7 @@ namespace { ss->ttPv = ttPv; } - // Step 11. If the position is not in TT, decrease depth by 2 + // Step 10. If the position is not in TT, decrease depth by 2 if ( PvNode && depth >= 6 && !ttMove) @@ -997,7 +990,7 @@ moves_loop: // When in check, search starts from here // Mark this node as being searched ThreadHolding th(thisThread, posKey, ss->ply); - // Step 12. Loop through all pseudo-legal moves until no moves remain + // Step 11. Loop through all pseudo-legal moves until no moves remain // or a beta cutoff occurs. while ((move = mp.next_move(moveCountPruning)) != MOVE_NONE) { @@ -1035,7 +1028,7 @@ moves_loop: // When in check, search starts from here // Calculate new depth for this move newDepth = depth - 1; - // Step 13. Pruning at shallow depth (~200 Elo) + // Step 12. Pruning at shallow depth (~200 Elo) if ( !rootNode && pos.non_pawn_material(us) && bestValue > VALUE_TB_LOSS_IN_MAX_PLY) @@ -1083,7 +1076,7 @@ moves_loop: // When in check, search starts from here } } - // Step 14. Extensions (~75 Elo) + // Step 13. Extensions (~75 Elo) // Singular extension search (~70 Elo). If all moves but one fail low on a // search of (alpha-s, beta-s), and just one fails high on (alpha, beta), @@ -1155,10 +1148,10 @@ moves_loop: // When in check, search starts from here [movedPiece] [to_sq(move)]; - // Step 15. Make the move + // Step 14. Make the move pos.do_move(move, st, givesCheck); - // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be + // Step 15. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be // re-searched at full depth. if ( depth >= 3 && moveCount > 1 + 2 * rootNode @@ -1258,7 +1251,7 @@ moves_loop: // When in check, search starts from here didLMR = false; } - // Step 17. Full depth search when LMR is skipped or fails high + // Step 16. Full depth search when LMR is skipped or fails high if (doFullDepthSearch) { value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); @@ -1285,12 +1278,12 @@ moves_loop: // When in check, search starts from here std::min(maxNextDepth, newDepth), false); } - // Step 18. Undo move + // Step 17. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // Step 19. Check for a new best move + // Step 18. Check for a new best move // Finished searching the move. If a stop occurred, the return value of // the search cannot be trusted, and we return immediately without // updating best move, PV and TT. @@ -1367,7 +1360,7 @@ moves_loop: // When in check, search starts from here return VALUE_DRAW; */ - // Step 20. Check for mate and stalemate + // Step 19. Check for mate and stalemate // All legal moves have been searched and if there are no legal moves, it // must be a mate or a stalemate. If we are in a singular extension search then // return a fail low score. -- 2.39.2