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Code Issues Releases Wiki Activity

Small cleanup in search.cpp

Browse source 
Also clarify some comments.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-01-03 10:00:29 +01:00
parent 12d8f74242
commit 0256db2a11
1 changed files with 123 additions and 134 deletions
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203
src/search.cpp
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@ -41,6 +41,8 @@
#include "tt.h" #include "tt.h"
#include "ucioption.h" #include "ucioption.h"
using std::cout;
using std::endl;
//// ////
//// Local definitions //// Local definitions
@ -93,13 +95,12 @@ namespace {
struct RootMove { struct RootMove {
RootMove(); RootMove();
bool operator<(const RootMove&); // used to sort bool operator<(const RootMove&) const; // Used to sort
Move move; Move move;
Value score; Value score;
int64_t nodes, cumulativeNodes; int64_t nodes, cumulativeNodes, ourBeta, theirBeta;
Move pv[PLY_MAX_PLUS_2]; Move pv[PLY_MAX_PLUS_2];
int64_t ourBeta, theirBeta;
}; };
@ -132,7 +133,7 @@ namespace {
/// Constants /// Constants
// Search depth at iteration 1 // Search depth at iteration 1
const Depth InitialDepth = OnePly /*+ OnePly/2*/; const Depth InitialDepth = OnePly;
// Depth limit for selective search // Depth limit for selective search
const Depth SelectiveDepth = 7 * OnePly; const Depth SelectiveDepth = 7 * OnePly;
@ -182,7 +183,7 @@ namespace {
// Each move futility margin is decreased // Each move futility margin is decreased
const Value IncrementalFutilityMargin = Value(0x8); const Value IncrementalFutilityMargin = Value(0x8);
// Razoring // Depth limit for razoring
const Depth RazorDepth = 4 * OnePly; const Depth RazorDepth = 4 * OnePly;
// Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply
@ -195,10 +196,10 @@ namespace {
/// Variables initialized by UCI options /// Variables initialized by UCI options
// Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes // Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes
int LMRPVMoves, LMRNonPVMoves; // heavy SMP read access for the latter int LMRPVMoves, LMRNonPVMoves;
// Depth limit for use of dynamic threat detection // Depth limit for use of dynamic threat detection
Depth ThreatDepth; // heavy SMP read access Depth ThreatDepth;
// Last seconds noise filtering (LSN) // Last seconds noise filtering (LSN)
const bool UseLSNFiltering = true; const bool UseLSNFiltering = true;
@ -207,13 +208,12 @@ namespace {
bool loseOnTime = false; bool loseOnTime = false;
// Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes. // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
// There is heavy SMP read access on these arrays
Depth CheckExtension[2], SingleReplyExtension[2], PawnPushTo7thExtension[2]; Depth CheckExtension[2], SingleReplyExtension[2], PawnPushTo7thExtension[2];
Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2]; Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
// Iteration counters // Iteration counters
int Iteration; int Iteration;
BetaCounterType BetaCounter; // has per-thread internal data BetaCounterType BetaCounter;
// Scores and number of times the best move changed for each iteration // Scores and number of times the best move changed for each iteration
IterationInfoType IterationInfo[PLY_MAX_PLUS_2]; IterationInfoType IterationInfo[PLY_MAX_PLUS_2];
@ -223,18 +223,13 @@ namespace {
int MultiPV; int MultiPV;
// Time managment variables // Time managment variables
int RootMoveNumber;
int SearchStartTime; int SearchStartTime;
int MaxNodes, MaxDepth; int MaxNodes, MaxDepth;
int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
int RootMoveNumber; bool InfiniteSearch, PonderSearch, StopOnPonderhit;
bool InfiniteSearch; bool AbortSearch, Quit;
bool PonderSearch; bool FailHigh, FailLow, Problem;
bool StopOnPonderhit;
bool AbortSearch; // heavy SMP read access
bool Quit;
bool FailHigh;
bool FailLow;
bool Problem;
// Show current line? // Show current line?
bool ShowCurrentLine; bool ShowCurrentLine;
@ -251,7 +246,7 @@ namespace {
Lock MPLock; Lock MPLock;
Lock IOLock; Lock IOLock;
bool AllThreadsShouldExit = false; bool AllThreadsShouldExit = false;
const int MaxActiveSplitPoints = 8; const int MaxActiveSplitPoints = 8; // FIXME, sync with UCI Option
SplitPoint SplitPointStack[THREAD_MAX][MaxActiveSplitPoints]; SplitPoint SplitPointStack[THREAD_MAX][MaxActiveSplitPoints];
bool Idle = true; bool Idle = true;
@ -328,8 +323,8 @@ namespace {
//// ////
/// perft() is our utility to verify move generation is bug free. All the /// perft() is our utility to verify move generation is bug free. All the legal
/// legal moves up to given depth are generated and counted and the sum returned. /// moves up to given depth are generated and counted and the sum returned.
int perft(Position& pos, Depth depth) int perft(Position& pos, Depth depth)
{ {
@ -377,32 +372,28 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
bookMove = OpeningBook.get_move(pos); bookMove = OpeningBook.get_move(pos);
if (bookMove != MOVE_NONE) if (bookMove != MOVE_NONE)
{ {
std::cout << "bestmove " << bookMove << std::endl; cout << "bestmove " << bookMove << endl;
return true; return true;
} }
} }
// Initialize global search variables // Initialize global search variables
Idle = false; Idle = StopOnPonderhit = AbortSearch = Quit = false;
FailHigh = FailLow = Problem = false;
SearchStartTime = get_system_time(); SearchStartTime = get_system_time();
ExactMaxTime = maxTime;
NodesSincePoll = 0;
InfiniteSearch = infinite;
PonderSearch = ponder;
for (int i = 0; i < THREAD_MAX; i++) for (int i = 0; i < THREAD_MAX; i++)
{ {
Threads[i].nodes = 0ULL; Threads[i].nodes = 0ULL;
Threads[i].failHighPly1 = false; Threads[i].failHighPly1 = false;
} }
NodesSincePoll = 0;
InfiniteSearch = infinite;
PonderSearch = ponder;
StopOnPonderhit = false;
AbortSearch = false;
Quit = false;
FailHigh = false;
FailLow = false;
Problem = false;
ExactMaxTime = maxTime;
if (button_was_pressed("New Game")) if (button_was_pressed("New Game"))
loseOnTime = false; // reset at the beginning of a new game loseOnTime = false; // Reset at the beginning of a new game
// Read UCI option values // Read UCI option values
TT.set_size(get_option_value_int("Hash")); TT.set_size(get_option_value_int("Hash"));
@ -469,7 +460,9 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
{ {
MaxSearchTime = myTime / 30 + myIncrement; MaxSearchTime = myTime / 30 + myIncrement;
AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100); AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
} else { // Blitz game without increment }
else // Blitz game without increment
{
MaxSearchTime = myTime / 30; MaxSearchTime = myTime / 30;
AbsoluteMaxSearchTime = myTime / 8; AbsoluteMaxSearchTime = myTime / 8;
} }
@ -479,9 +472,10 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
if (movesToGo == 1) if (movesToGo == 1)
{ {
MaxSearchTime = myTime / 2; MaxSearchTime = myTime / 2;
AbsoluteMaxSearchTime = AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
(myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4); }
} else { else
{
MaxSearchTime = myTime / Min(movesToGo, 20); MaxSearchTime = myTime / Min(movesToGo, 20);
AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3); AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
} }
@ -513,13 +507,12 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
// Write information to search log file // Write information to search log file
if (UseLogFile) if (UseLogFile)
LogFile << "Searching: " << pos.to_fen() << std::endl LogFile << "Searching: " << pos.to_fen() << endl
<< "infinite: " << infinite << "infinite: " << infinite
<< " ponder: " << ponder << " ponder: " << ponder
<< " time: " << myTime << " time: " << myTime
<< " increment: " << myIncrement << " increment: " << myIncrement
<< " moves to go: " << movesToGo << std::endl; << " moves to go: " << movesToGo << endl;
// LSN filtering. Used only for developing purpose. Disabled by default. // LSN filtering. Used only for developing purpose. Disabled by default.
if ( UseLSNFiltering if ( UseLSNFiltering
@ -527,13 +520,13 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
{ {
// Step 2. If after last move we decided to lose on time, do it now! // Step 2. If after last move we decided to lose on time, do it now!
while (SearchStartTime + myTime + 1000 > get_system_time()) while (SearchStartTime + myTime + 1000 > get_system_time())
; // wait here /* wait here */;
} }
// We're ready to start thinking. Call the iterative deepening loop function // We're ready to start thinking. Call the iterative deepening loop function
Value v = id_loop(pos, searchMoves); Value v = id_loop(pos, searchMoves);
// LSN filtering. Used only for developing purpose. Disabled by default.
if (UseLSNFiltering) if (UseLSNFiltering)
{ {
// Step 1. If this is sudden death game and our position is hopeless, // Step 1. If this is sudden death game and our position is hopeless,
@ -686,7 +679,7 @@ namespace {
// Print RootMoveList c'tor startup scoring to the standard output, // Print RootMoveList c'tor startup scoring to the standard output,
// so that we print information also for iteration 1. // so that we print information also for iteration 1.
std::cout << "info depth " << 1 << "\ninfo depth " << 1 cout << "info depth " << 1 << "\ninfo depth " << 1
<< " score " << value_to_string(rml.get_move_score(0)) << " score " << value_to_string(rml.get_move_score(0))
<< " time " << current_search_time() << " time " << current_search_time()
<< " nodes " << nodes_searched() << " nodes " << nodes_searched()
@ -716,7 +709,7 @@ namespace {
if (Iteration <= 5) if (Iteration <= 5)
ExtraSearchTime = 0; ExtraSearchTime = 0;
std::cout << "info depth " << Iteration << std::endl; cout << "info depth " << Iteration << endl;
// Calculate dynamic search window based on previous iterations // Calculate dynamic search window based on previous iterations
Value alpha, beta; Value alpha, beta;
@ -775,7 +768,7 @@ namespace {
speculatedValue = Min(Max(speculatedValue, -VALUE_INFINITE), VALUE_INFINITE); speculatedValue = Min(Max(speculatedValue, -VALUE_INFINITE), VALUE_INFINITE);
IterationInfo[Iteration] = IterationInfoType(value, speculatedValue); IterationInfo[Iteration] = IterationInfoType(value, speculatedValue);
// Erase the easy move if it differs from the new best move // Drop the easy move if it differs from the new best move
if (ss[0].pv[0] != EasyMove) if (ss[0].pv[0] != EasyMove)
EasyMove = MOVE_NONE; EasyMove = MOVE_NONE;
@ -786,7 +779,8 @@ namespace {
// Time to stop? // Time to stop?
bool stopSearch = false; bool stopSearch = false;
// Stop search early if there is only a single legal move // Stop search early if there is only a single legal move,
// we search up to Iteration 6 anyway to get a proper score.
if (Iteration >= 6 && rml.move_count() == 1) if (Iteration >= 6 && rml.move_count() == 1)
stopSearch = true; stopSearch = true;
@ -840,10 +834,10 @@ namespace {
wait_for_stop_or_ponderhit(); wait_for_stop_or_ponderhit();
else else
// Print final search statistics // Print final search statistics
std::cout << "info nodes " << nodes_searched() cout << "info nodes " << nodes_searched()
<< " nps " << nps() << " nps " << nps()
<< " time " << current_search_time() << " time " << current_search_time()
<< " hashfull " << TT.full() << std::endl; << " hashfull " << TT.full() << endl;
// Print the best move and the ponder move to the standard output // Print the best move and the ponder move to the standard output
if (ss[0].pv[0] == MOVE_NONE) if (ss[0].pv[0] == MOVE_NONE)
@ -851,11 +845,11 @@ namespace {
ss[0].pv[0] = rml.get_move(0); ss[0].pv[0] = rml.get_move(0);
ss[0].pv[1] = MOVE_NONE; ss[0].pv[1] = MOVE_NONE;
} }
std::cout << "bestmove " << ss[0].pv[0]; cout << "bestmove " << ss[0].pv[0];
if (ss[0].pv[1] != MOVE_NONE) if (ss[0].pv[1] != MOVE_NONE)
std::cout << " ponder " << ss[0].pv[1]; cout << " ponder " << ss[0].pv[1];
std::cout << std::endl; cout << endl;
if (UseLogFile) if (UseLogFile)
{ {
@ -865,14 +859,13 @@ namespace {
if (dbg_show_hit_rate) if (dbg_show_hit_rate)
dbg_print_hit_rate(LogFile); dbg_print_hit_rate(LogFile);
StateInfo st; LogFile << "\nNodes: " << nodes_searched()
LogFile << "Nodes: " << nodes_searched() << std::endl << "\nNodes/second: " << nps()
<< "Nodes/second: " << nps() << std::endl << "\nBest move: " << move_to_san(p, ss[0].pv[0]);
<< "Best move: " << move_to_san(p, ss[0].pv[0]) << std::endl;
StateInfo st;
p.do_move(ss[0].pv[0], st); p.do_move(ss[0].pv[0], st);
LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1]) LogFile << "\nPonder move: " << move_to_san(p, ss[0].pv[1]) << endl;
<< std::endl << std::endl;
} }
return rml.get_move_score(0); return rml.get_move_score(0);
} }
@ -880,8 +873,7 @@ namespace {
// root_search() is the function which searches the root node. It is // root_search() is the function which searches the root node. It is
// similar to search_pv except that it uses a different move ordering // similar to search_pv except that it uses a different move ordering
// scheme (perhaps we should try to use this at internal PV nodes, too?) // scheme and prints some information to the standard output.
// and prints some information to the standard output.
Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta) { Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta) {
@ -908,8 +900,7 @@ namespace {
RootMoveNumber = i + 1; RootMoveNumber = i + 1;
FailHigh = false; FailHigh = false;
// Remember the node count before the move is searched. The node counts // Save the current node count before the move is searched
// are used to sort the root moves at the next iteration.
nodes = nodes_searched(); nodes = nodes_searched();
// Reset beta cut-off counters // Reset beta cut-off counters
@ -918,9 +909,10 @@ namespace {
// Pick the next root move, and print the move and the move number to // Pick the next root move, and print the move and the move number to
// the standard output. // the standard output.
move = ss[0].currentMove = rml.get_move(i); move = ss[0].currentMove = rml.get_move(i);
if (current_search_time() >= 1000) if (current_search_time() >= 1000)
std::cout << "info currmove " << move cout << "info currmove " << move
<< " currmovenumber " << i + 1 << std::endl; << " currmovenumber " << RootMoveNumber << endl;
// Decide search depth for this move // Decide search depth for this move
bool moveIsCheck = pos.move_is_check(move); bool moveIsCheck = pos.move_is_check(move);
@ -939,17 +931,21 @@ namespace {
alpha = -VALUE_INFINITE; alpha = -VALUE_INFINITE;
value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
// If the value has dropped a lot compared to the last iteration, // If the value has dropped a lot compared to the last iteration,
// set the boolean variable Problem to true. This variable is used // set the boolean variable Problem to true. This variable is used
// for time managment: When Problem is true, we try to complete the // for time managment: When Problem is true, we try to complete the
// current iteration before playing a move. // current iteration before playing a move.
Problem = (Iteration >= 2 && value <= IterationInfo[Iteration-1].value - ProblemMargin); Problem = ( Iteration >= 2
&& value <= IterationInfo[Iteration - 1].value - ProblemMargin);
if (Problem && StopOnPonderhit) if (Problem && StopOnPonderhit)
StopOnPonderhit = false; StopOnPonderhit = false;
} }
else else
{ {
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
if ( newDepth >= 3*OnePly if ( newDepth >= 3*OnePly
&& i >= MultiPV + LMRPVMoves && i >= MultiPV + LMRPVMoves
&& !dangerous && !dangerous
@ -964,12 +960,13 @@ namespace {
if (value > alpha) if (value > alpha)
{ {
value = -search(pos, ss, -alpha, newDepth, 1, true, 0); value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
if (value > alpha) if (value > alpha)
{ {
// Fail high! Set the boolean variable FailHigh to true, and // Fail high! Set the boolean variable FailHigh to true, and
// re-search the move with a big window. The variable FailHigh is // re-search the move using a PV search. The variable FailHigh
// used for time managment: We try to avoid aborting the search // is used for time managment: We try to avoid aborting the
// prematurely during a fail high research. // search prematurely during a fail high research.
FailHigh = true; FailHigh = true;
value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
} }
@ -986,14 +983,12 @@ namespace {
if (AbortSearch) if (AbortSearch)
break; break;
// Remember the node count for this move. The node counts are used to // Remember beta-cutoff and searched nodes counts for this move. The
// sort the root moves at the next iteration. // info is used to sort the root moves at the next iteration.
rml.set_move_nodes(i, nodes_searched() - nodes);
// Remember the beta-cutoff statistics
int64_t our, their; int64_t our, their;
BetaCounter.read(pos.side_to_move(), our, their); BetaCounter.read(pos.side_to_move(), our, their);
rml.set_beta_counters(i, our, their); rml.set_beta_counters(i, our, their);
rml.set_move_nodes(i, nodes_searched() - nodes);
assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
@ -1018,27 +1013,28 @@ namespace {
BestMoveChangesByIteration[Iteration]++; BestMoveChangesByIteration[Iteration]++;
// Print search information to the standard output // Print search information to the standard output
std::cout << "info depth " << Iteration cout << "info depth " << Iteration
<< " score " << value_to_string(value) << " score " << value_to_string(value)
<< ((value >= beta)? << ((value >= beta) ? " lowerbound" :
" lowerbound" : ((value <= alpha)? " upperbound" : "")) ((value <= alpha)? " upperbound" : ""))
<< " time " << current_search_time() << " time " << current_search_time()
<< " nodes " << nodes_searched() << " nodes " << nodes_searched()
<< " nps " << nps() << " nps " << nps()
<< " pv "; << " pv ";
for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
std::cout << ss[0].pv[j] << " "; cout << ss[0].pv[j] << " ";
std::cout << std::endl; cout << endl;
if (UseLogFile) if (UseLogFile)
LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, {
((value >= beta)? VALUE_TYPE_LOWER ValueType type = (value >= beta ? VALUE_TYPE_LOWER
: ((value <= alpha)? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)), : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
ss[0].pv)
<< std::endl;
LogFile << pretty_pv(pos, current_search_time(), Iteration,
nodes_searched(), value, type, ss[0].pv) << endl;
}
if (value > alpha) if (value > alpha)
alpha = value; alpha = value;
@ -1052,8 +1048,7 @@ namespace {
rml.sort_multipv(i); rml.sort_multipv(i);
for (int j = 0; j < Min(MultiPV, rml.move_count()); j++) for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
{ {
int k; cout << "info multipv " << j + 1
std::cout << "info multipv " << j + 1
<< " score " << value_to_string(rml.get_move_score(j)) << " score " << value_to_string(rml.get_move_score(j))
<< " depth " << ((j <= i)? Iteration : Iteration - 1) << " depth " << ((j <= i)? Iteration : Iteration - 1)
<< " time " << current_search_time() << " time " << current_search_time()
@ -1061,14 +1056,14 @@ namespace {
<< " nps " << nps() << " nps " << nps()
<< " pv "; << " pv ";
for (k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++) for (int k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++)
std::cout << rml.get_move_pv(j, k) << " "; cout << rml.get_move_pv(j, k) << " ";
std::cout << std::endl; cout << endl;
} }
alpha = rml.get_move_score(Min(i, MultiPV-1)); alpha = rml.get_move_score(Min(i, MultiPV-1));
} }
} // New best move case } // PV move or new best move
assert(alpha >= oldAlpha); assert(alpha >= oldAlpha);
@ -1165,10 +1160,9 @@ namespace {
// Decide the new search depth // Decide the new search depth
ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous); ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
// We want to extend the TT move if it is much better then remaining ones. // Singular extension search. We extend the TT move if its value is much better than
// To verify this we do a reduced search on all the other moves but the ttMove, // its siblings. To verify this we do a reduced search on all the other moves but the
// if result is lower then TT value minus a margin then we assume ttMove is the // ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
// only one playable. It is a kind of relaxed single reply extension.
if ( depth >= 6 * OnePly if ( depth >= 6 * OnePly
&& tte && tte
&& move == tte->move() && move == tte->move()
@ -1182,8 +1176,6 @@ namespace {
{ {
Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move); Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
// If search result is well below the foreseen score of the ttMove then we
// assume ttMove is the only one realistically playable and we extend it.
if (excValue < ttValue - SingleReplyMargin) if (excValue < ttValue - SingleReplyMargin)
ext = OnePly; ext = OnePly;
} }
@ -1470,10 +1462,9 @@ namespace {
// Decide the new search depth // Decide the new search depth
ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous); ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
// We want to extend the TT move if it is much better then remaining ones. // Singular extension search. We extend the TT move if its value is much better than
// To verify this we do a reduced search on all the other moves but the ttMove, // its siblings. To verify this we do a reduced search on all the other moves but the
// if result is lower then TT value minus a margin then we assume ttMove is the // ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
// only one playable. It is a kind of relaxed single reply extension.
if ( depth >= 8 * OnePly if ( depth >= 8 * OnePly
&& tte && tte
&& move == tte->move() && move == tte->move()
@ -1488,8 +1479,6 @@ namespace {
{ {
Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move); Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
// If search result is well below the foreseen score of the ttMove then we
// assume ttMove is the only one realistically playable and we extend it.
if (excValue < ttValue - SingleReplyMargin) if (excValue < ttValue - SingleReplyMargin)
ext = OnePly; ext = OnePly;
} }
@ -2103,7 +2092,7 @@ namespace {
// than a move m2 if it has a higher score, or if the moves // than a move m2 if it has a higher score, or if the moves
// have equal score but m1 has the higher node count. // have equal score but m1 has the higher node count.
bool RootMove::operator<(const RootMove& m) { bool RootMove::operator<(const RootMove& m) const {
if (score != m.score) if (score != m.score)
return (score < m.score); return (score < m.score);
@ -2635,8 +2624,8 @@ namespace {
if (dbg_show_hit_rate) if (dbg_show_hit_rate)
dbg_print_hit_rate(); dbg_print_hit_rate();
std::cout << "info nodes " << nodes_searched() << " nps " << nps() cout << "info nodes " << nodes_searched() << " nps " << nps()
<< " time " << t << " hashfull " << TT.full() << std::endl; << " time " << t << " hashfull " << TT.full() << endl;
lock_release(&IOLock); lock_release(&IOLock);
if (ShowCurrentLine) if (ShowCurrentLine)
Threads[0].printCurrentLine = true; Threads[0].printCurrentLine = true;
@ -2687,11 +2676,11 @@ namespace {
if (!Threads[threadID].idle) if (!Threads[threadID].idle)
{ {
lock_grab(&IOLock); lock_grab(&IOLock);
std::cout << "info currline " << (threadID + 1); cout << "info currline " << (threadID + 1);
for (int p = 0; p < ply; p++) for (int p = 0; p < ply; p++)
std::cout << " " << ss[p].currentMove; cout << " " << ss[p].currentMove;
std::cout << std::endl; cout << endl;
lock_release(&IOLock); lock_release(&IOLock);
} }
Threads[threadID].printCurrentLine = false; Threads[threadID].printCurrentLine = false;