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Merge branch 'master' into clusterMergeMaster5

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This commit is contained in:
Joost VandeVondele
2019-05-01 08:23:22 +02:00
parent 4cdb6386d8 7ede1ed071
commit 85327828c9
21 changed files with 186 additions and 231 deletions
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src/search.cpp
+76 -58
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@@ -18,7 +18,6 @@
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstring> // For std::memset
@@ -69,10 +68,10 @@ namespace {
}
// Reductions lookup table, initialized at startup
int Reductions[64]; // [depth or moveNumber]
int Reductions[MAX_MOVES]; // [depth or moveNumber]
template <bool PvNode> Depth reduction(bool i, Depth d, int mn) {
int r = Reductions[std::min(d / ONE_PLY, 63)] * Reductions[std::min(mn, 63)] / 1024;
int r = Reductions[d / ONE_PLY] * Reductions[mn] / 1024;
return ((r + 512) / 1024 + (!i && r > 1024) - PvNode) * ONE_PLY;
}
@@ -86,11 +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
@@ -117,13 +115,6 @@ namespace {
void update_quiet_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietCount, int bonus);
void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCount, int bonus);
inline bool gives_check(const Position& pos, Move move) {
Color us = pos.side_to_move();
return type_of(move) == NORMAL && !(pos.blockers_for_king(~us) & pos.pieces(us))
? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move)
: pos.gives_check(move);
}
// perft() is our utility to verify move generation. All the leaf nodes up
// to the given depth are generated and counted, and the sum is returned.
template<bool Root>
@@ -157,7 +148,7 @@ namespace {
void Search::init() {
for (int i = 1; i < 64; ++i)
for (int i = 1; i < MAX_MOVES; ++i)
Reductions[i] = int(1024 * std::log(i) / std::sqrt(1.95));
}
@@ -171,12 +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() {
@@ -203,8 +194,11 @@ void MainThread::search() {
else
{
for (Thread* th : Threads)
{
th->bestMoveChanges = 0;
if (th != this)
th->start_searching();
}
Thread::search(); // Let's start searching!
}
@@ -235,8 +229,9 @@ void MainThread::search() {
if (Limits.npmsec)
Time.availableNodes += Limits.inc[us] - Cluster::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()
@@ -310,9 +305,9 @@ 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];
@@ -320,7 +315,7 @@ 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));
@@ -331,9 +326,6 @@ void Thread::search() {
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
if (mainThread)
mainThread->bestMoveChanges = 0;
size_t multiPV = Options["MultiPV"];
Skill skill(Options["Skill Level"]);
@@ -354,7 +346,7 @@ 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));
@@ -365,7 +357,7 @@ 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
@@ -504,15 +496,20 @@ void Thread::search() {
&& !Threads.stop
&& !mainThread->stopOnPonderhit)
{
double fallingEval = (306 + 9 * (mainThread->previousScore - bestValue)) / 581.0;
fallingEval = std::max(0.5, std::min(1.5, fallingEval));
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
timeReduction = lastBestMoveDepth + 10 * ONE_PLY < completedDepth ? 1.95 : 1.0;
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
@@ -578,7 +575,7 @@ 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;
@@ -624,8 +621,7 @@ 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);
@@ -647,6 +643,15 @@ namespace {
: 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 - 6 * (pos.count<ALL_PIECES>() > 14)
&& ss->ply > 36 - 6 * (pos.count<ALL_PIECES>() > 14)
&& ttHit
&& tte->depth() > depth
&& pos.count<PAWN>() > 0)
return VALUE_DRAW;
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
&& ttHit
@@ -663,9 +668,8 @@ 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
@@ -734,16 +738,16 @@ 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
@@ -756,15 +760,14 @@ 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;
Cluster::save(thisThread, tte,
posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE,
pureStaticEval);
eval);
}
// Step 7. Razoring (~2 Elo)
@@ -788,7 +791,7 @@ 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))
@@ -820,7 +823,7 @@ 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<NonPV>(pos, ss, beta-1, beta, depth-R, false);
@@ -871,8 +874,7 @@ namespace {
}
// Step 11. Internal iterative deepening (~2 Elo)
if ( depth >= 8 * ONE_PLY
&& !ttMove)
if (depth >= 8 * ONE_PLY && !ttMove)
{
search<NT>(pos, ss, alpha, beta, depth - 7 * ONE_PLY, cutNode);
@@ -886,6 +888,7 @@ 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,
@@ -893,8 +896,8 @@ 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);
@@ -927,7 +930,7 @@ moves_loop: // When in check, search starts from here
extension = DEPTH_ZERO;
captureOrPromotion = pos.capture_or_promotion(move);
movedPiece = pos.moved_piece(move);
givesCheck = gives_check(pos, move);
givesCheck = pos.gives_check(move);
// Step 13. Extensions (~70 Elo)
@@ -947,8 +950,9 @@ moves_loop: // When in check, search starts from here
&& 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<NonPV>(pos, ss, singularBeta - 1, singularBeta, depth / 2, cutNode);
value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode);
ss->excludedMove = MOVE_NONE;
if (value < singularBeta)
@@ -972,6 +976,20 @@ moves_loop: // When in check, search starts from here
else if (type_of(move) == CASTLING)
extension = ONE_PLY;
// Shuffle extension
else if ( PvNode
&& pos.rule50_count() > 18
&& ss->ply > 18
&& depth < 3 * ONE_PLY
&& ss->ply < 3 * thisThread->rootDepth / ONE_PLY) // To avoid infinite loops
extension = ONE_PLY;
// 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
newDepth = depth - ONE_PLY + extension;
@@ -981,7 +999,7 @@ 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
@@ -992,7 +1010,8 @@ moves_loop: // When in check, search starts from here
continue;
// Reduced depth of the next LMR search
int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO);
lmrDepth /= ONE_PLY;
// Countermoves based pruning (~20 Elo)
if ( lmrDepth < 3 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
@@ -1137,8 +1156,8 @@ 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<MainThread*>(thisThread)->bestMoveChanges;
if (moveCount > 1)
++thisThread->bestMoveChanges;
}
else
// All other moves but the PV are set to the lowest value: this
@@ -1225,7 +1244,7 @@ moves_loop: // When in check, search starts from here
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);
@@ -1264,8 +1283,7 @@ 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;
@@ -1355,7 +1373,7 @@ moves_loop: // When in check, search starts from here
{
assert(is_ok(move));
givesCheck = gives_check(pos, move);
givesCheck = pos.gives_check(move);
moveCount++;