X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=37fc2ec48a8bfa99b7e4a125f68f540fe1ebaba0;hp=cfa737dbd6773bf72cd460a19eb71f9b143232e1;hb=a8de07cc26999e2fef7298a63bfe349aaa4650fa;hpb=76f1807baa90eb69f66001d25df2a28533f9406f
diff --git a/src/search.cpp b/src/search.cpp
index cfa737db..37fc2ec4 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -18,6 +18,7 @@
along with this program. If not, see .
*/
+#include
#include
#include
#include // For std::memset
@@ -67,11 +68,11 @@ namespace {
}
// Reductions lookup table, initialized at startup
- int Reductions[64]; // [depth or moveNumber]
+ int Reductions[MAX_MOVES]; // [depth or moveNumber]
- template Depth reduction(bool i, Depth d, int mn) {
- int r = Reductions[std::min(d / ONE_PLY, 63)] * Reductions[std::min(mn, 63)] / 1024;
- return ((r + 512) / 1024 + (!i && r > 1024) - PvNode) * ONE_PLY;
+ Depth reduction(bool i, Depth d, int mn) {
+ int r = Reductions[d / ONE_PLY] * Reductions[mn];
+ return ((r + 512) / 1024 + (!i && r > 1024)) * ONE_PLY;
}
constexpr int futility_move_count(bool improving, int depth) {
@@ -84,11 +85,10 @@ namespace {
return d > 17 ? 0 : 29 * d * d + 138 * d - 134;
}
- // Add a small random component to draw evaluations to keep search dynamic
- // and to avoid 3fold-blindness.
+ // Add a small random component to draw evaluations to avoid 3fold-blindness
Value value_draw(Depth depth, Thread* thisThread) {
- return depth < 4 ? VALUE_DRAW
- : VALUE_DRAW + Value(2 * (thisThread->nodes.load(std::memory_order_relaxed) % 2) - 1);
+ return depth < 4 * ONE_PLY ? VALUE_DRAW
+ : VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1);
}
// Skill structure is used to implement strength limit
@@ -148,8 +148,8 @@ namespace {
void Search::init() {
- for (int i = 1; i < 64; ++i)
- Reductions[i] = int(1024 * std::log(i) / std::sqrt(1.95));
+ for (int i = 1; i < MAX_MOVES; ++i)
+ Reductions[i] = int(22.9 * std::log(i));
}
@@ -162,12 +162,12 @@ void Search::clear() {
Time.availableNodes = 0;
TT.clear();
Threads.clear();
- Tablebases::init(Options["SyzygyPath"]); // Free up mapped files
+ Tablebases::init(Options["SyzygyPath"]); // Free mapped files
}
-/// MainThread::search() is called by the main thread when the program receives
-/// the UCI 'go' command. It searches from the root position and outputs the "bestmove".
+/// MainThread::search() is started when the program receives the UCI 'go'
+/// command. It searches from the root position and outputs the "bestmove".
void MainThread::search() {
@@ -192,8 +192,11 @@ void MainThread::search() {
else
{
for (Thread* th : Threads)
+ {
+ th->bestMoveChanges = 0;
if (th != this)
th->start_searching();
+ }
Thread::search(); // Let's start searching!
}
@@ -221,8 +224,9 @@ void MainThread::search() {
if (Limits.npmsec)
Time.availableNodes += Limits.inc[us] - Threads.nodes_searched();
- // Check if there are threads with a better score than main thread
Thread* bestThread = this;
+
+ // Check if there are threads with a better score than main thread
if ( Options["MultiPV"] == 1
&& !Limits.depth
&& !Skill(Options["Skill Level"]).enabled()
@@ -235,21 +239,15 @@ void MainThread::search() {
for (Thread* th: Threads)
minScore = std::min(minScore, th->rootMoves[0].score);
- // Vote according to score and depth
+ // Vote according to score and depth, and select the best thread
for (Thread* th : Threads)
{
- int64_t s = th->rootMoves[0].score - minScore + 1;
- votes[th->rootMoves[0].pv[0]] += 200 + s * s * int(th->completedDepth);
- }
+ votes[th->rootMoves[0].pv[0]] +=
+ (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
- // Select best thread
- auto bestVote = votes[this->rootMoves[0].pv[0]];
- for (Thread* th : Threads)
- if (votes[th->rootMoves[0].pv[0]] > bestVote)
- {
- bestVote = votes[th->rootMoves[0].pv[0]];
+ if (votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
bestThread = th;
- }
+ }
}
previousScore = bestThread->rootMoves[0].score;
@@ -273,9 +271,9 @@ void MainThread::search() {
void Thread::search() {
- // To allow access to (ss-5) up to (ss+2), the stack must be oversized.
+ // To allow access to (ss-7) up to (ss+2), the stack must be oversized.
// The former is needed to allow update_continuation_histories(ss-1, ...),
- // which accesses its argument at ss-4, also near the root.
+ // which accesses its argument at ss-6, also near the root.
// The latter is needed for statScores and killer initialization.
Stack stack[MAX_PLY+10], *ss = stack+7;
Move pv[MAX_PLY+1];
@@ -283,7 +281,7 @@ void Thread::search() {
Move lastBestMove = MOVE_NONE;
Depth lastBestMoveDepth = DEPTH_ZERO;
MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
- double timeReduction = 1.0;
+ double timeReduction = 1, totBestMoveChanges = 0;
Color us = rootPos.side_to_move();
std::memset(ss-7, 0, 10 * sizeof(Stack));
@@ -294,10 +292,7 @@ void Thread::search() {
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
- if (mainThread)
- mainThread->bestMoveChanges = 0;
-
- size_t multiPV = Options["MultiPV"];
+ multiPV = Options["MultiPV"];
Skill skill(Options["Skill Level"]);
// When playing with strength handicap enable MultiPV search that we will
@@ -317,7 +312,7 @@ void Thread::search() {
: Options["Analysis Contempt"] == "Black" && us == WHITE ? -ct
: ct;
- // In evaluate.cpp the evaluation is from the white point of view
+ // Evaluation score is from the white point of view
contempt = (us == WHITE ? make_score(ct, ct / 2)
: -make_score(ct, ct / 2));
@@ -328,7 +323,7 @@ void Thread::search() {
{
// Age out PV variability metric
if (mainThread)
- mainThread->bestMoveChanges *= 0.517;
+ totBestMoveChanges /= 2;
// Save the last iteration's scores before first PV line is searched and
// all the move scores except the (new) PV are set to -VALUE_INFINITE.
@@ -405,17 +400,14 @@ void Thread::search() {
beta = (alpha + beta) / 2;
alpha = std::max(bestValue - delta, -VALUE_INFINITE);
+ failedHighCnt = 0;
if (mainThread)
- {
- failedHighCnt = 0;
mainThread->stopOnPonderhit = false;
- }
}
else if (bestValue >= beta)
{
beta = std::min(bestValue + delta, VALUE_INFINITE);
- if (mainThread)
- ++failedHighCnt;
+ ++failedHighCnt;
}
else
break;
@@ -459,7 +451,7 @@ void Thread::search() {
&& !Threads.stop
&& !mainThread->stopOnPonderhit)
{
- double fallingEval = (306 + 9 * (mainThread->previousScore - bestValue)) / 581.0;
+ double fallingEval = (314 + 9 * (mainThread->previousScore - bestValue)) / 581.0;
fallingEval = clamp(fallingEval, 0.5, 1.5);
// If the bestMove is stable over several iterations, reduce time accordingly
@@ -467,7 +459,12 @@ void Thread::search() {
double reduction = std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction;
// Use part of the gained time from a previous stable move for the current move
- double bestMoveInstability = 1.0 + mainThread->bestMoveChanges;
+ for (Thread* th : Threads)
+ {
+ totBestMoveChanges += th->bestMoveChanges;
+ th->bestMoveChanges = 0;
+ }
+ double bestMoveInstability = 1 + totBestMoveChanges / Threads.size();
// Stop the search if we have only one legal move, or if available time elapsed
if ( rootMoves.size() == 1
@@ -533,17 +530,17 @@ namespace {
Key posKey;
Move ttMove, move, excludedMove, bestMove;
Depth extension, newDepth;
- Value bestValue, value, ttValue, eval, maxValue, pureStaticEval;
+ Value bestValue, value, ttValue, eval, maxValue;
bool ttHit, ttPv, inCheck, givesCheck, improving;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture;
Piece movedPiece;
- int moveCount, captureCount, quietCount;
+ int moveCount, captureCount, quietCount, singularLMR;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
Color us = pos.side_to_move();
- moveCount = captureCount = quietCount = ss->moveCount = 0;
+ moveCount = captureCount = quietCount = singularLMR = ss->moveCount = 0;
bestValue = -VALUE_INFINITE;
maxValue = VALUE_INFINITE;
@@ -579,8 +576,7 @@ namespace {
assert(0 <= ss->ply && ss->ply < MAX_PLY);
(ss+1)->ply = ss->ply + 1;
- ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
- ss->continuationHistory = &thisThread->continuationHistory[NO_PIECE][0];
+ (ss+1)->excludedMove = bestMove = MOVE_NONE;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
Square prevSq = to_sq((ss-1)->currentMove);
@@ -589,7 +585,10 @@ namespace {
// starts with statScore = 0. Later grandchildren start with the last calculated
// statScore of the previous grandchild. This influences the reduction rules in
// LMR which are based on the statScore of parent position.
- (ss+2)->statScore = 0;
+ if (rootNode)
+ (ss + 4)->statScore = 0;
+ else
+ (ss + 2)->statScore = 0;
// Step 4. Transposition table lookup. We don't want the score of a partial
// search to overwrite a previous full search TT value, so we use a different
@@ -600,16 +599,7 @@ namespace {
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
: ttHit ? tte->move() : MOVE_NONE;
- ttPv = (ttHit && tte->is_pv()) || (PvNode && depth > 4 * ONE_PLY);
-
- // if position has been searched at higher depths and we are shuffling, return value_draw
- if (pos.rule50_count() > 36
- && ss->ply > 36
- && depth < 3 * ONE_PLY
- && ttHit
- && tte->depth() > depth
- && pos.count() > 0)
- return VALUE_DRAW;
+ ttPv = PvNode || (ttHit && tte->is_pv());
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
@@ -627,9 +617,8 @@ namespace {
if (!pos.capture_or_promotion(ttMove))
update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
- // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted
- if ( ((ss-1)->moveCount == 1 || (ss-1)->currentMove == (ss-1)->killers[0])
- && !pos.captured_piece())
+ // Extra penalty for early quiet moves of the previous ply
+ if ((ss-1)->moveCount <= 2 && !pos.captured_piece())
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
}
// Penalty for a quiet ttMove that fails low
@@ -697,16 +686,16 @@ namespace {
// Step 6. Static evaluation of the position
if (inCheck)
{
- ss->staticEval = eval = pureStaticEval = VALUE_NONE;
+ ss->staticEval = eval = VALUE_NONE;
improving = false;
goto moves_loop; // Skip early pruning when in check
}
else if (ttHit)
{
// Never assume anything on values stored in TT
- ss->staticEval = eval = pureStaticEval = tte->eval();
+ ss->staticEval = eval = tte->eval();
if (eval == VALUE_NONE)
- ss->staticEval = eval = pureStaticEval = evaluate(pos);
+ ss->staticEval = eval = evaluate(pos);
// Can ttValue be used as a better position evaluation?
if ( ttValue != VALUE_NONE
@@ -719,13 +708,12 @@ namespace {
{
int bonus = -(ss-1)->statScore / 512;
- pureStaticEval = evaluate(pos);
- ss->staticEval = eval = pureStaticEval + bonus;
+ ss->staticEval = eval = evaluate(pos) + bonus;
}
else
- ss->staticEval = eval = pureStaticEval = -(ss-1)->staticEval + 2 * Eval::Tempo;
+ ss->staticEval = eval = -(ss-1)->staticEval + 2 * Eval::Tempo;
- tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, pureStaticEval);
+ tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
}
// Step 7. Razoring (~2 Elo)
@@ -749,7 +737,7 @@ namespace {
&& (ss-1)->currentMove != MOVE_NULL
&& (ss-1)->statScore < 23200
&& eval >= beta
- && pureStaticEval >= beta - 36 * depth / ONE_PLY + 225
+ && ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
&& !excludedMove
&& pos.non_pawn_material(us)
&& (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -781,7 +769,7 @@ namespace {
// Do verification search at high depths, with null move pruning disabled
// for us, until ply exceeds nmpMinPly.
- thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / 4;
+ thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / (4 * ONE_PLY);
thisThread->nmpColor = us;
Value v = search(pos, ss, beta-1, beta, depth-R, false);
@@ -832,8 +820,7 @@ namespace {
}
// Step 11. Internal iterative deepening (~2 Elo)
- if ( depth >= 8 * ONE_PLY
- && !ttMove)
+ if (depth >= 8 * ONE_PLY && !ttMove)
{
search(pos, ss, alpha, beta, depth - 7 * ONE_PLY, cutNode);
@@ -847,6 +834,7 @@ moves_loop: // When in check, search starts from here
const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
nullptr, (ss-4)->continuationHistory,
nullptr, (ss-6)->continuationHistory };
+
Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
@@ -854,8 +842,8 @@ moves_loop: // When in check, search starts from here
contHist,
countermove,
ss->killers);
- value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
+ value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
moveCountPruning = false;
ttCapture = ttMove && pos.capture_or_promotion(ttMove);
@@ -882,6 +870,12 @@ moves_loop: // When in check, search starts from here
sync_cout << "info depth " << depth / ONE_PLY
<< " currmove " << UCI::move(move, pos.is_chess960())
<< " currmovenumber " << moveCount + thisThread->pvIdx << sync_endl;
+
+ // In MultiPV mode also skip moves which will be searched later as PV moves
+ if (rootNode && std::count(thisThread->rootMoves.begin() + thisThread->pvIdx + 1,
+ thisThread->rootMoves.begin() + thisThread->multiPV, move))
+ continue;
+
if (PvNode)
(ss+1)->pv = nullptr;
@@ -901,27 +895,35 @@ moves_loop: // When in check, search starts from here
&& move == ttMove
&& !rootNode
&& !excludedMove // Avoid recursive singular search
- /* && ttValue != VALUE_NONE Already implicit in the next condition */
+ /* && ttValue != VALUE_NONE Already implicit in the next condition */
&& abs(ttValue) < VALUE_KNOWN_WIN
&& (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY
&& pos.legal(move))
{
Value singularBeta = ttValue - 2 * depth / ONE_PLY;
+ Depth halfDepth = depth / (2 * ONE_PLY) * ONE_PLY; // ONE_PLY invariant
ss->excludedMove = move;
- value = search(pos, ss, singularBeta - 1, singularBeta, depth / 2, cutNode);
+ value = search(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode);
ss->excludedMove = MOVE_NONE;
if (value < singularBeta)
+ {
extension = ONE_PLY;
+ singularLMR++;
+
+ if (value < singularBeta - std::min(3 * depth / ONE_PLY, 39))
+ singularLMR++;
+ }
// Multi-cut pruning
// Our ttMove is assumed to fail high, and now we failed high also on a reduced
// search without the ttMove. So we assume this expected Cut-node is not singular,
- // that is multiple moves fail high, and we can prune the whole subtree by returning
- // the hard beta bound.
- else if (cutNode && singularBeta > beta)
- return beta;
+ // that multiple moves fail high, and we can prune the whole subtree by returning
+ // a soft bound.
+ else if ( eval >= beta
+ && singularBeta >= beta)
+ return singularBeta;
}
// Check extension (~2 Elo)
@@ -929,12 +931,21 @@ moves_loop: // When in check, search starts from here
&& (pos.blockers_for_king(~us) & from_sq(move) || pos.see_ge(move)))
extension = ONE_PLY;
+ // Castling extension
+ else if (type_of(move) == CASTLING)
+ extension = ONE_PLY;
+
// Shuffle extension
- else if(pos.rule50_count() > 14 && ss->ply > 14 && depth < 3 * ONE_PLY && PvNode)
+ else if ( PvNode
+ && pos.rule50_count() > 18
+ && depth < 3 * ONE_PLY
+ && ++thisThread->shuffleExts < thisThread->nodes.load(std::memory_order_relaxed) / 4) // To avoid too many extensions
extension = ONE_PLY;
- // Castling extension
- else if (type_of(move) == CASTLING)
+ // Passed pawn extension
+ else if ( move == ss->killers[0]
+ && pos.advanced_pawn_push(move)
+ && pos.pawn_passed(us, to_sq(move)))
extension = ONE_PLY;
// Calculate new depth for this move
@@ -946,18 +957,19 @@ moves_loop: // When in check, search starts from here
&& bestValue > VALUE_MATED_IN_MAX_PLY)
{
// Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
- moveCountPruning = moveCount >= futility_move_count(improving,depth / ONE_PLY);
+ moveCountPruning = moveCount >= futility_move_count(improving, depth / ONE_PLY);
if ( !captureOrPromotion
&& !givesCheck
- && !pos.advanced_pawn_push(move))
+ && (!pos.advanced_pawn_push(move) || pos.non_pawn_material(~us) > BishopValueMg))
{
// Move count based pruning (~30 Elo)
if (moveCountPruning)
continue;
// Reduced depth of the next LMR search
- int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
+ int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO);
+ lmrDepth /= ONE_PLY;
// Countermoves based pruning (~20 Elo)
if ( lmrDepth < 3 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
@@ -975,7 +987,8 @@ moves_loop: // When in check, search starts from here
if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))
continue;
}
- else if (!pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo)
+ else if ((!givesCheck || !extension)
+ && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo)
continue;
}
@@ -999,19 +1012,24 @@ moves_loop: // When in check, search starts from here
// Step 16. Reduced depth search (LMR). If the move fails high it will be
// re-searched at full depth.
if ( depth >= 3 * ONE_PLY
- && moveCount > 1
- && (!captureOrPromotion || moveCountPruning))
+ && moveCount > 1 + 3 * rootNode
+ && ( !captureOrPromotion
+ || moveCountPruning
+ || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha))
{
- Depth r = reduction(improving, depth, moveCount);
+ Depth r = reduction(improving, depth, moveCount);
// Decrease reduction if position is or has been on the PV
if (ttPv)
- r -= ONE_PLY;
+ r -= 2 * ONE_PLY;
// Decrease reduction if opponent's move count is high (~10 Elo)
if ((ss-1)->moveCount > 15)
r -= ONE_PLY;
+ // Decrease reduction if move has been singularly extended
+ r -= singularLMR * ONE_PLY;
+
if (!captureOrPromotion)
{
// Increase reduction if ttMove is a capture (~0 Elo)
@@ -1046,7 +1064,7 @@ moves_loop: // When in check, search starts from here
r -= ss->statScore / 20000 * ONE_PLY;
}
- Depth d = std::max(newDepth - std::max(r, DEPTH_ZERO), ONE_PLY);
+ Depth d = clamp(newDepth - r, ONE_PLY, newDepth);
value = -search(pos, ss+1, -(alpha+1), -alpha, d, true);
@@ -1102,8 +1120,8 @@ moves_loop: // When in check, search starts from here
// We record how often the best move has been changed in each
// iteration. This information is used for time management: When
// the best move changes frequently, we allocate some more time.
- if (moveCount > 1 && thisThread == Threads.main())
- ++static_cast(thisThread)->bestMoveChanges;
+ if (moveCount > 1)
+ ++thisThread->bestMoveChanges;
}
else
// All other moves but the PV are set to the lowest value: this
@@ -1189,7 +1207,7 @@ moves_loop: // When in check, search starts from here
tte->save(posKey, value_to_tt(bestValue, ss->ply), ttPv,
bestValue >= beta ? BOUND_LOWER :
PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
- depth, bestMove, pureStaticEval);
+ depth, bestMove, ss->staticEval);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
@@ -1197,8 +1215,8 @@ moves_loop: // When in check, search starts from here
}
- // qsearch() is the quiescence search function, which is called by the main
- // search function with depth zero, or recursively with depth less than ONE_PLY.
+ // qsearch() is the quiescence search function, which is called by the main search
+ // function with zero depth, or recursively with further decreasing depth per call.
template
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
@@ -1228,8 +1246,7 @@ moves_loop: // When in check, search starts from here
Thread* thisThread = pos.this_thread();
(ss+1)->ply = ss->ply + 1;
- ss->currentMove = bestMove = MOVE_NONE;
- ss->continuationHistory = &thisThread->continuationHistory[NO_PIECE][0];
+ bestMove = MOVE_NONE;
inCheck = pos.checkers();
moveCount = 0;
@@ -1353,6 +1370,7 @@ moves_loop: // When in check, search starts from here
// Don't search moves with negative SEE values
if ( (!inCheck || evasionPrunable)
+ && (!givesCheck || !(pos.blockers_for_king(~pos.side_to_move()) & from_sq(move)))
&& !pos.see_ge(move))
continue;
@@ -1463,7 +1481,7 @@ moves_loop: // When in check, search starts from here
void update_capture_stats(const Position& pos, Move move,
Move* captures, int captureCount, int bonus) {
- CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory;
+ CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory;
Piece moved_piece = pos.moved_piece(move);
PieceType captured = type_of(pos.piece_on(to_sq(move)));
@@ -1704,7 +1722,7 @@ void Tablebases::rank_root_moves(Position& pos, Search::RootMoves& rootMoves) {
}
else
{
- // Assign the same rank to all moves
+ // Clean up if root_probe() and root_probe_wdl() have failed
for (auto& m : rootMoves)
m.tbRank = 0;
}