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Code style fixes in search.cpp

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Some code style triviality.

No functional change.
This commit is contained in:
Marco Costalba 2018-02-12 22:57:42 +01:00 • committed by Stéphane Nicolet
parent baab8be324
commit 4c57cf0ead
2 changed files with 128 additions and 130 deletions
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198
src/search.cpp
View file

@ -63,11 +63,11 @@ namespace {
enum NodeType { NonPV, PV };
// Sizes and phases of the skip-blocks, used for distributing search depths across the threads
const int skipSize[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 };
const int skipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
const int SkipSize[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 };
const int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
// Razoring and futility margin based on depth
const int razor_margin = 600;
// Razoring and futility margins
const int RazorMargin = 600;
Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
// Futility and reductions lookup tables, initialized at startup
@ -105,7 +105,7 @@ namespace {
Value value_from_tt(Value v, int ply);
void update_pv(Move* pv, Move move, Move* childPv);
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus);
void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, int bonus);
void update_quiet_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, int bonus);
void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCnt, int bonus);
// perft() is our utility to verify move generation. All the leaf nodes up
@ -137,7 +137,7 @@ namespace {
} // namespace
/// Search::init() is called during startup to initialize various lookup tables
/// Search::init() is called at startup to initialize various lookup tables
void Search::init() {
@ -252,7 +252,7 @@ void MainThread::search() {
previousScore = bestThread->rootMoves[0].score;
// Send new PV when needed
// Send again PV info if we have a new best thread
if (bestThread != this)
sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth, -VALUE_INFINITE, VALUE_INFINITE) << sync_endl;
@ -287,10 +287,7 @@ void Thread::search() {
beta = VALUE_INFINITE;
if (mainThread)
{
mainThread->failedLow = false;
mainThread->bestMoveChanges = 0;
}
mainThread->bestMoveChanges = 0, mainThread->failedLow = false;
size_t multiPV = Options["MultiPV"];
Skill skill(Options["Skill Level"]);
@ -302,21 +299,21 @@ void Thread::search() {
multiPV = std::min(multiPV, rootMoves.size());
int contempt = Options["Contempt"] * PawnValueEg / 100; // From centipawns
Eval::Contempt = (us == WHITE ? make_score(contempt, contempt / 2)
: -make_score(contempt, contempt / 2));
int ct = Options["Contempt"] * PawnValueEg / 100; // From centipawns
Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2)
: -make_score(ct, ct / 2));
// Iterative deepening loop until requested to stop or the target depth is reached
while ( (rootDepth += ONE_PLY) < DEPTH_MAX
&& !Threads.stop
&& !(Limits.depth && mainThread && rootDepth / ONE_PLY > Limits.depth))
{
// Distribute search depths across the threads
if (idx)
// Distribute search depths across the helper threads
if (idx > 0)
{
int i = (idx - 1) % 20;
if (((rootDepth / ONE_PLY + rootPos.game_ply() + skipPhase[i]) / skipSize[i]) % 2)
continue;
if (((rootDepth / ONE_PLY + rootPos.game_ply() + SkipPhase[i]) / SkipSize[i]) % 2)
continue; // Retry with an incremented rootDepth
}
// Age out PV variability metric
@ -341,18 +338,18 @@ void Thread::search() {
alpha = std::max(rootMoves[PVIdx].previousScore - delta,-VALUE_INFINITE);
beta = std::min(rootMoves[PVIdx].previousScore + delta, VALUE_INFINITE);
// Adjust contempt based on current situation
contempt = Options["Contempt"] * PawnValueEg / 100; // From centipawns
contempt += bestValue > 500 ? 50: // Dynamic contempt
// Adjust contempt based on current bestValue
ct = Options["Contempt"] * PawnValueEg / 100 // From centipawns
+ (bestValue > 500 ? 50: // Dynamic contempt
bestValue < -500 ? -50:
bestValue / 10;
bestValue / 10);
Eval::Contempt = (us == WHITE ? make_score(contempt, contempt / 2)
: -make_score(contempt, contempt / 2));
Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2)
: -make_score(ct, ct / 2));
}
// Start with a small aspiration window and, in the case of a fail
// high/low, re-search with a bigger window until we're not failing
// high/low, re-search with a bigger window until we don't fail
// high/low anymore.
while (true)
{
@ -366,9 +363,9 @@ void Thread::search() {
// search the already searched PV lines are preserved.
std::stable_sort(rootMoves.begin() + PVIdx, rootMoves.end());
// If search has been stopped, we break immediately. Sorting and
// writing PV back to TT is safe because RootMoves is still
// valid, although it refers to the previous iteration.
// If search has been stopped, we break immediately. Sorting is
// safe because RootMoves is still valid, although it refers to
// the previous iteration.
if (Threads.stop)
break;
@ -433,27 +430,26 @@ void Thread::search() {
skill.pick_best(multiPV);
// Do we have time for the next iteration? Can we stop searching now?
if (Limits.use_time_management())
if ( Limits.use_time_management()
&& !Threads.stop
&& !Threads.stopOnPonderhit)
{
if (!Threads.stop && !Threads.stopOnPonderhit)
{
// Stop the search if only one legal move is available, or if all
// of the available time has been used
const int F[] = { mainThread->failedLow,
bestValue - mainThread->previousScore };
int improvingFactor = std::max(229, std::min(715, 357 + 119 * F[0] - 6 * F[1]));
double unstablePvFactor = 1 + mainThread->bestMoveChanges;
// if the bestMove is stable over several iterations, reduce time for this move,
// the longer the move has been stable, the more.
// Use part of the gained time from a previous stable move for the current move.
timeReduction = 1;
// If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = 1.0;
for (int i : {3, 4, 5})
if (lastBestMoveDepth * i < completedDepth)
timeReduction *= 1.3;
// Use part of the gained time from a previous stable move for the current move
double unstablePvFactor = 1.0 + mainThread->bestMoveChanges;
unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.51) / timeReduction;
// Stop the search if we have only one legal move, or if available time elapsed
if ( rootMoves.size() == 1
|| Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 605)
{
@ -466,7 +462,6 @@ void Thread::search() {
}
}
}
}
if (!mainThread)
return;
@ -527,8 +522,10 @@ namespace {
if (!rootNode)
{
// Step 2. Check for aborted search and immediate draw
if (Threads.stop.load(std::memory_order_relaxed) || pos.is_draw(ss->ply) || ss->ply >= MAX_PLY)
return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos) : VALUE_DRAW;
if ( Threads.stop.load(std::memory_order_relaxed)
|| pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : VALUE_DRAW;
// Step 3. Mate distance pruning. Even if we mate at the next move our score
// would be at best mate_in(ss->ply+1), but if alpha is already bigger because
@ -554,7 +551,7 @@ namespace {
// search to overwrite a previous full search TT value, so we use a different
// position key in case of an excluded move.
excludedMove = ss->excludedMove;
posKey = pos.key() ^ Key(excludedMove << 16); // isn't a very good hash
posKey = pos.key() ^ Key(excludedMove << 16); // Isn't a very good hash
tte = TT.probe(posKey, ttHit);
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
ttMove = rootNode ? thisThread->rootMoves[thisThread->PVIdx].pv[0]
@ -574,7 +571,7 @@ namespace {
if (ttValue >= beta)
{
if (!pos.capture_or_promotion(ttMove))
update_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
// Extra penalty for a quiet TT move in previous ply when it gets refuted
if ((ss-1)->moveCount == 1 && !pos.captured_piece())
@ -591,7 +588,7 @@ namespace {
return ttValue;
}
// Step 4a. Tablebase probe
// Step 5. Tablebases probe
if (!rootNode && TB::Cardinality)
{
int piecesCount = pos.count<ALL_PIECES>();
@ -638,13 +635,12 @@ namespace {
}
}
// Step 5. Evaluate the position statically
// Step 6. Evaluate the position statically
if (inCheck)
{
ss->staticEval = eval = VALUE_NONE;
goto moves_loop;
}
else if (ttHit)
{
// Never assume anything on values stored in TT
@ -658,7 +654,7 @@ namespace {
}
else
{
eval = ss->staticEval =
ss->staticEval = eval =
(ss-1)->currentMove != MOVE_NULL ? evaluate(pos)
: -(ss-1)->staticEval + 2 * Eval::Tempo;
@ -669,34 +665,33 @@ namespace {
if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move()))
goto moves_loop;
// Step 6. Razoring (skipped when in check)
// Step 7. Razoring (skipped when in check)
if ( !PvNode
&& depth < 4 * ONE_PLY
&& eval + razor_margin <= alpha)
&& eval + RazorMargin <= alpha)
{
if (depth <= ONE_PLY)
return qsearch<NonPV, false>(pos, ss, alpha, alpha+1);
Value ralpha = alpha - razor_margin;
Value ralpha = alpha - RazorMargin;
Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1);
if (v <= ralpha)
return v;
}
// Step 7. Futility pruning: child node (skipped when in check)
// Step 8. Futility pruning: child node (skipped when in check)
if ( !rootNode
&& depth < 7 * ONE_PLY
&& eval - futility_margin(depth) >= beta
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins
return eval;
// Step 8. Null move search with verification search (is omitted in PV nodes)
// Step 9. Null move search with verification search
if ( !PvNode
&& eval >= beta
&& ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
&& (ss->ply >= thisThread->nmp_ply || ss->ply % 2 != thisThread->nmp_odd))
{
assert(eval - beta >= 0);
// Null move dynamic reduction based on depth and value
@ -719,8 +714,8 @@ namespace {
if (abs(beta) < VALUE_KNOWN_WIN && (depth < 12 * ONE_PLY || thisThread->nmp_ply))
return nullValue;
// Do verification search at high depths
// disable null move pruning for side to move for the first part of the remaining search tree
// Do verification search at high depths. Disable null move pruning
// for side to move for the first part of the remaining search tree.
thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4;
thisThread->nmp_odd = ss->ply % 2;
@ -734,17 +729,16 @@ namespace {
}
}
// Step 9. ProbCut (skipped when in check)
// Step 10. ProbCut (skipped when in check)
// 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
&& depth >= 5 * ONE_PLY
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
{
Value rbeta = std::min(beta + 200, VALUE_INFINITE);
assert(is_ok((ss-1)->currentMove));
Value rbeta = std::min(beta + 200, VALUE_INFINITE);
MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);
while ((move = mp.next_move()) != MOVE_NONE)
@ -754,6 +748,7 @@ namespace {
ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)];
assert(depth >= 5 * ONE_PLY);
pos.do_move(move, st);
value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false);
pos.undo_move(move);
@ -762,19 +757,19 @@ namespace {
}
}
// Step 10. Internal iterative deepening (skipped when in check)
// Step 11. Internal iterative deepening (skipped when in check)
if ( depth >= 6 * ONE_PLY
&& !ttMove
&& (PvNode || ss->staticEval + 256 >= beta))
{
Depth d = (3 * depth / (4 * ONE_PLY) - 2) * ONE_PLY;
Depth d = 3 * depth / 4 - 2 * ONE_PLY;
search<NT>(pos, ss, alpha, beta, d, cutNode, true);
tte = TT.probe(posKey, ttHit);
ttMove = ttHit ? tte->move() : MOVE_NONE;
}
moves_loop: // When in check search starts from here
moves_loop: // When in check, search starts from here
const PieceToHistory* contHist[] = { (ss-1)->contHistory, (ss-2)->contHistory, nullptr, (ss-4)->contHistory };
Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
@ -796,8 +791,8 @@ moves_loop: // When in check search starts from here
ttCapture = false;
pvExact = PvNode && ttHit && tte->bound() == BOUND_EXACT;
// Step 11. Loop through moves
// Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs
// Step 12. Loop through all pseudo-legal moves until no moves remain
// or a beta cutoff occurs.
while ((move = mp.next_move(skipQuiets)) != MOVE_NONE)
{
assert(is_ok(move));
@ -818,7 +813,6 @@ 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;
if (PvNode)
(ss+1)->pv = nullptr;
@ -833,27 +827,26 @@ moves_loop: // When in check search starts from here
moveCountPruning = depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
// Step 12. Singular and Gives Check Extensions
// Step 13. Extensions
// Singular extension search. If all moves but one fail low on a search of
// (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
// is singular and should be extended. To verify this we do a reduced search
// on all the other moves but the ttMove and if the result is lower than
// ttValue minus a margin then we will extend the ttMove.
// Singular extension search. If all moves but one fail low on a search
// of (alpha-s, beta-s), and just one fails high on (alpha, beta), then
// that move is singular and should be extended. To verify this we do a
// reduced search on on all the other moves but the ttMove and if the
// result is lower than ttValue minus a margin then we will extend the ttMove.
if ( singularExtensionNode
&& move == ttMove
&& pos.legal(move))
{
Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE);
Depth d = (depth / (2 * ONE_PLY)) * ONE_PLY;
ss->excludedMove = move;
value = search<NonPV>(pos, ss, rBeta - 1, rBeta, d, cutNode, true);
value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode, true);
ss->excludedMove = MOVE_NONE;
if (value < rBeta)
extension = ONE_PLY;
}
else if ( givesCheck
else if ( givesCheck // Check extension
&& !moveCountPruning
&& pos.see_ge(move))
extension = ONE_PLY;
@ -861,7 +854,7 @@ moves_loop: // When in check search starts from here
// Calculate new depth for this move
newDepth = depth - ONE_PLY + extension;
// Step 13. Pruning at shallow depth
// Step 14. Pruning at shallow depth
if ( !rootNode
&& pos.non_pawn_material(pos.side_to_move())
&& bestValue > VALUE_MATED_IN_MAX_PLY)
@ -920,10 +913,10 @@ moves_loop: // When in check search starts from here
ss->currentMove = move;
ss->contHistory = &thisThread->contHistory[movedPiece][to_sq(move)];
// Step 14. Make the move
// Step 15. Make the move
pos.do_move(move, st, givesCheck);
// Step 15. Reduced depth search (LMR). If the move fails high it will be
// 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
@ -984,7 +977,7 @@ moves_loop: // When in check search starts from here
else
doFullDepthSearch = !PvNode || moveCount > 1;
// Step 16. Full depth search when LMR is skipped or fails high
// Step 17. Full depth search when LMR is skipped or fails high
if (doFullDepthSearch)
value = newDepth < ONE_PLY ?
givesCheck ? -qsearch<NonPV, true>(pos, ss+1, -(alpha+1), -alpha)
@ -1005,12 +998,12 @@ moves_loop: // When in check search starts from here
: - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, false);
}
// Step 17. Undo move
// Step 18. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// Step 18. Check for a new best move
// Step 19. 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.
@ -1068,10 +1061,14 @@ moves_loop: // When in check search starts from here
}
}
if (!captureOrPromotion && move != bestMove && quietCount < 64)
quietsSearched[quietCount++] = move;
else if (captureOrPromotion && move != bestMove && captureCount < 32)
if (move != bestMove)
{
if (captureOrPromotion && captureCount < 32)
capturesSearched[captureCount++] = move;
else if (!captureOrPromotion && quietCount < 64)
quietsSearched[quietCount++] = move;
}
}
// The following condition would detect a stop only after move loop has been
@ -1096,7 +1093,7 @@ moves_loop: // When in check search starts from here
{
// Quiet best move: update move sorting heuristics
if (!pos.capture_or_promotion(bestMove))
update_stats(pos, ss, bestMove, quietsSearched, quietCount, stat_bonus(depth));
update_quiet_stats(pos, ss, bestMove, quietsSearched, quietCount, stat_bonus(depth));
else
update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth));
@ -1133,20 +1130,20 @@ moves_loop: // When in check search starts from here
const bool PvNode = NT == PV;
assert(InCheck == bool(pos.checkers()));
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);
assert(depth / ONE_PLY * ONE_PLY == depth);
assert(InCheck == bool(pos.checkers()));
Move pv[MAX_PLY+1];
StateInfo st;
TTEntry* tte;
Key posKey;
Move ttMove, move, bestMove;
Depth ttDepth;
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
bool ttHit, givesCheck, evasionPrunable;
Depth ttDepth;
int moveCount;
if (PvNode)
@ -1156,13 +1153,14 @@ moves_loop: // When in check search starts from here
ss->pv[0] = MOVE_NONE;
}
ss->currentMove = bestMove = MOVE_NONE;
(ss+1)->ply = ss->ply + 1;
ss->currentMove = bestMove = MOVE_NONE;
moveCount = 0;
// Check for an instant draw or if the maximum ply has been reached
if (pos.is_draw(ss->ply) || ss->ply >= MAX_PLY)
return ss->ply >= MAX_PLY && !InCheck ? evaluate(pos) : VALUE_DRAW;
// Check for an immediate draw or maximum ply reached
if ( pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
return (ss->ply >= MAX_PLY && !InCheck) ? evaluate(pos) : VALUE_DRAW;
assert(0 <= ss->ply && ss->ply < MAX_PLY);
@ -1403,9 +1401,9 @@ moves_loop: // When in check search starts from here
}
// update_stats() updates move sorting heuristics when a new quiet best move is found
// update_quiet_stats() updates move sorting heuristics when a new quiet best move is found
void update_stats(const Position& pos, Stack* ss, Move move,
void update_quiet_stats(const Position& pos, Stack* ss, Move move,
Move* quiets, int quietsCnt, int bonus) {
if (ss->killers[0] != move)
@ -1414,9 +1412,9 @@ moves_loop: // When in check search starts from here
ss->killers[0] = move;
}
Color c = pos.side_to_move();
Color us = pos.side_to_move();
Thread* thisThread = pos.this_thread();
thisThread->mainHistory.update(c, move, bonus);
thisThread->mainHistory.update(us, move, bonus);
update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus);
if (is_ok((ss-1)->currentMove))
@ -1428,7 +1426,7 @@ moves_loop: // When in check search starts from here
// Decrease all the other played quiet moves
for (int i = 0; i < quietsCnt; ++i)
{
thisThread->mainHistory.update(c, quiets[i], -bonus);
thisThread->mainHistory.update(us, quiets[i], -bonus);
update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
}
@ -1468,16 +1466,15 @@ moves_loop: // When in check search starts from here
} // namespace
// check_time() is used to print debug info and, more importantly, to detect
// when we are out of available time and thus stop the search.
/// MainThread::check_time() is used to print debug info and, more importantly,
/// to detect when we are out of available time and thus stop the search.
void MainThread::check_time() {
if (--callsCnt > 0)
return;
// At low node count increase the checking rate to about 0.1% of nodes
// otherwise use a default value.
// When using nodes, ensure checking rate is not lower than 0.1% of nodes
callsCnt = Limits.nodes ? std::min(4096, int(Limits.nodes / 1024)) : 4096;
static TimePoint lastInfoTime = now();
@ -1491,7 +1488,7 @@ moves_loop: // When in check search starts from here
dbg_print();
}
// An engine may not stop pondering until told so by the GUI
// We should not stop pondering until told so by the GUI
if (Threads.ponder)
return;
@ -1587,6 +1584,7 @@ bool RootMove::extract_ponder_from_tt(Position& pos) {
return pv.size() > 1;
}
void Tablebases::filter_root_moves(Position& pos, Search::RootMoves& rootMoves) {
RootInTB = false;

2
src/thread.cpp
View file

@ -147,7 +147,7 @@ void ThreadPool::clear() {
main()->callsCnt = 0;
main()->previousScore = VALUE_INFINITE;
main()->previousTimeReduction = 1;
main()->previousTimeReduction = 1.0;
}
/// ThreadPool::start_thinking() wakes up main thread waiting in idle_loop() and