From 95b8f3f8005598fc3ad07a7a8f6440d828cabc29 Mon Sep 17 00:00:00 2001 From: VoyagerOne Date: Sun, 23 Aug 2020 12:04:50 -0400 Subject: [PATCH] Remove Reduce Depth Remove Reduce Depth at PV nodes. STC: LLR: 2.94 (-2.94,2.94) {-1.25,0.25} Total: 56760 W: 6299 L: 6236 D: 44225 Ptnml(0-2): 286, 4843, 18076, 4872, 303 https://tests.stockfishchess.org/tests/view/5f41356087a5c3c63d8f53c9 LTC: LLR: 2.95 (-2.94,2.94) {-0.75,0.25} Total: 17496 W: 954 L: 865 D: 15677 Ptnml(0-2): 13, 768, 7098, 855, 14 https://tests.stockfishchess.org/tests/view/5f41bb7687a5c3c63d8f53f9 closes https://github.com/official-stockfish/Stockfish/pull/3055 Bench: 3555051 --- src/search.cpp | 24 +++++++++--------------- 1 file changed, 9 insertions(+), 15 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index 2ca64a01..d6b611a3 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -940,12 +940,6 @@ namespace { } } - // Step 11. If the position is not in TT, decrease depth by 2 - if ( PvNode - && depth >= 6 - && !ttMove) - depth -= 2; - moves_loop: // When in check, search starts from here const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, @@ -969,7 +963,7 @@ 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) { @@ -1007,7 +1001,7 @@ 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) @@ -1065,7 +1059,7 @@ 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), @@ -1148,10 +1142,10 @@ 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 + 2 * (PvNode && abs(bestValue) < 2) @@ -1254,7 +1248,7 @@ 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); @@ -1282,12 +1276,12 @@ moves_loop: // When in check, search starts from here value = -search(pos, ss+1, -beta, -alpha, 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. @@ -1364,7 +1358,7 @@ 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