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Remove razoring

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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
This commit is contained in:
Unai Corzo 2020-12-26 13:48:04 +01:00 • committed by Joost VandeVondele
parent 8985c210a1
commit 8ec97d161e
1 changed files with 14 additions and 21 deletions
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35
src/search.cpp
View file

@ -62,8 +62,7 @@ namespace {
constexpr uint64_t TtHitAverageWindow = 4096; constexpr uint64_t TtHitAverageWindow = 4096;
constexpr uint64_t TtHitAverageResolution = 1024; constexpr uint64_t TtHitAverageResolution = 1024;
// Razor and futility margins // Futility margin
constexpr int RazorMargin = 510;
Value futility_margin(Depth d, bool improving) { Value futility_margin(Depth d, bool improving) {
return Value(234 * (d - improving)); return Value(234 * (d - improving));
} }
@ -822,12 +821,6 @@ namespace {
thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus; 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<NT>(pos, ss, alpha, beta);
// Set up improving flag that is used in various pruning heuristics // Set up improving flag that is used in various pruning heuristics
// We define position as improving if static evaluation of position is better // We define position as improving if static evaluation of position is better
// Than the previous static evaluation at our turn // 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-4)->staticEval || (ss-4)->staticEval == VALUE_NONE
: ss->staticEval > (ss-2)->staticEval; : ss->staticEval > (ss-2)->staticEval;
// Step 8. Futility pruning: child node (~50 Elo) // Step 7. Futility pruning: child node (~50 Elo)
if ( !PvNode if ( !PvNode
&& depth < 9 && depth < 9
&& eval - futility_margin(depth, improving) >= beta && eval - futility_margin(depth, improving) >= beta
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins && eval < VALUE_KNOWN_WIN) // Do not return unproven wins
return eval; return eval;
// Step 9. Null move search with verification search (~40 Elo) // Step 8. Null move search with verification search (~40 Elo)
if ( !PvNode if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL && (ss-1)->currentMove != MOVE_NULL
&& (ss-1)->statScore < 22977 && (ss-1)->statScore < 22977
@ -895,7 +888,7 @@ namespace {
probCutBeta = beta + 194 - 49 * improving; 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 // 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. // much above beta, we can (almost) safely prune the previous move.
if ( !PvNode if ( !PvNode
@ -968,7 +961,7 @@ namespace {
ss->ttPv = ttPv; 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 if ( PvNode
&& depth >= 6 && depth >= 6
&& !ttMove) && !ttMove)
@ -997,7 +990,7 @@ moves_loop: // When in check, search starts from here
// Mark this node as being searched // Mark this node as being searched
ThreadHolding th(thisThread, posKey, ss->ply); 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. // or a beta cutoff occurs.
while ((move = mp.next_move(moveCountPruning)) != MOVE_NONE) 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 // Calculate new depth for this move
newDepth = depth - 1; newDepth = depth - 1;
// Step 13. Pruning at shallow depth (~200 Elo) // Step 12. Pruning at shallow depth (~200 Elo)
if ( !rootNode if ( !rootNode
&& pos.non_pawn_material(us) && pos.non_pawn_material(us)
&& bestValue > VALUE_TB_LOSS_IN_MAX_PLY) && 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 // 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), // 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] [movedPiece]
[to_sq(move)]; [to_sq(move)];
// Step 15. Make the move // Step 14. Make the move
pos.do_move(move, st, givesCheck); 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. // re-searched at full depth.
if ( depth >= 3 if ( depth >= 3
&& moveCount > 1 + 2 * rootNode && moveCount > 1 + 2 * rootNode
@ -1258,7 +1251,7 @@ moves_loop: // When in check, search starts from here
didLMR = false; 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) if (doFullDepthSearch)
{ {
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); value = -search<NonPV>(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); std::min(maxNextDepth, newDepth), false);
} }
// Step 18. Undo move // Step 17. Undo move
pos.undo_move(move); pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); 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 // Finished searching the move. If a stop occurred, the return value of
// the search cannot be trusted, and we return immediately without // the search cannot be trusted, and we return immediately without
// updating best move, PV and TT. // updating best move, PV and TT.
@ -1367,7 +1360,7 @@ moves_loop: // When in check, search starts from here
return VALUE_DRAW; 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 // 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 // must be a mate or a stalemate. If we are in a singular extension search then
// return a fail low score. // return a fail low score.