////
#include <cassert>
+#include <cmath>
#include <cstring>
#include <fstream>
#include <iostream>
#include "book.h"
#include "evaluate.h"
#include "history.h"
+#include "maxgain.h"
#include "misc.h"
#include "movegen.h"
#include "movepick.h"
/// Variables initialized by UCI options
- // Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes
- int LMRPVMoves, LMRNonPVMoves;
-
// Depth limit for use of dynamic threat detection
Depth ThreatDepth;
bool UseLogFile;
std::ofstream LogFile;
+ // Natural logarithmic lookup table and its getter function
+ double lnArray[512];
+ inline double ln(int i) { return lnArray[i]; }
+
// MP related variables
int ActiveThreads = 1;
Depth MinimumSplitDepth;
// History table
History H;
+ // MaxGain table
+ MaxGain MG;
/// Functions
//// Functions
////
-//FIXME: HACK
-static double lnArray[512];
-
-inline double ln(int i)
-{
- return lnArray[i];
-}
/// perft() is our utility to verify move generation is bug free. All the legal
/// moves up to given depth are generated and counted and the sum returned.
MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
- LMRPVMoves = get_option_value_int("Full Depth Moves (PV nodes)") + 1;
- LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1;
ThreatDepth = get_option_value_int("Threat Depth") * OnePly;
Chess960 = get_option_value_bool("UCI_Chess960");
{
ActiveThreads = newActiveThreads;
init_eval(ActiveThreads);
+ // HACK: init_eval() destroys the static castleRightsMask[] array in the
+ // Position class. The below line repairs the damage.
+ Position p(pos.to_fen());
+ assert(pos.is_ok());
}
// Wake up sleeping threads
/// and initializes the split point stack and the global locks and condition
/// objects.
-#include <cmath> //FIXME: HACK
-
void init_threads() {
- // FIXME: HACK!!
- for (int i = 0; i < 512; i++)
- lnArray[i] = log(double(i));
-
volatile int i;
+ bool ok;
#if !defined(_MSC_VER)
pthread_t pthread[1];
#endif
+ // Init our logarithmic lookup table
+ for (i = 0; i < 512; i++)
+ lnArray[i] = log(double(i)); // log() returns base-e logarithm
+
for (i = 0; i < THREAD_MAX; i++)
Threads[i].activeSplitPoints = 0;
for (i = 1; i < THREAD_MAX; i++)
{
#if !defined(_MSC_VER)
- pthread_create(pthread, NULL, init_thread, (void*)(&i));
+ ok = (pthread_create(pthread, NULL, init_thread, (void*)(&i)) == 0);
#else
DWORD iID[1];
- CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID);
+ ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID) != NULL);
#endif
+ if (!ok)
+ {
+ cout << "Failed to create thread number " << i << endl;
+ Application::exit_with_failure();
+ }
+
// Wait until the thread has finished launching
while (!Threads[i].running);
}
currentMove = threatMove = MOVE_NONE;
reduction = Depth(0);
eval = VALUE_NONE;
+ evalInfo = NULL;
}
void SearchStack::initKillers() {
Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta) {
Value oldAlpha = alpha;
- Value value;
+ Value value = -VALUE_INFINITE;
CheckInfo ci(pos);
// Loop through all the moves in the root move list
{
// 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.
+ bool doFullDepthSearch = true;
+
if ( depth >= 3*OnePly // FIXME was newDepth
&& !dangerous
&& !captureOrPromotion
{
ss[0].reduction = Depth(int(floor(red * int(OnePly))));
value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0);
+ doFullDepthSearch = (value > alpha);
}
- else
- value = alpha + 1; // Just to trigger next condition
- } else
- value = alpha + 1; // Just to trigger next condition
+ }
- if (value > alpha)
+ if (doFullDepthSearch)
{
value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
assert(threadID >= 0 && threadID < ActiveThreads);
Move movesSearched[256];
- EvalInfo ei;
StateInfo st;
const TTEntry* tte;
Move ttMove, move;
Value oldAlpha, value;
bool isCheck, mateThreat, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
int moveCount = 0;
- Value bestValue = -VALUE_INFINITE;
+ Value bestValue = value = -VALUE_INFINITE;
if (depth < OnePly)
return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- if (pos.is_draw())
+ if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- if (ply >= PLY_MAX - 1)
- return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
-
// Mate distance pruning
oldAlpha = alpha;
alpha = Max(value_mated_in(ply), alpha);
{
// 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.
+ bool doFullDepthSearch = true;
+
if ( depth >= 3*OnePly
&& !dangerous
&& !captureOrPromotion
{
ss[ply].reduction = Depth(int(floor(red * int(OnePly))));
value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID);
+ doFullDepthSearch = (value > alpha);
}
- else
- value = alpha + 1; // Just to trigger next condition
}
- else
- value = alpha + 1; // Just to trigger next condition
- if (value > alpha) // Go with full depth non-pv search
+ if (doFullDepthSearch) // Go with full depth non-pv search
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
const TTEntry* tte;
Move ttMove, move;
Depth ext, newDepth;
- Value staticValue, nullValue, value, futilityValue, futilityValueScaled;
+ Value bestValue, staticValue, nullValue, value, futilityValue, futilityValueScaled;
bool isCheck, useFutilityPruning, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
bool mateThreat = false;
int moveCount = 0;
- Value bestValue = -VALUE_INFINITE;
+ futilityValue = staticValue = bestValue = value = -VALUE_INFINITE;
if (depth < OnePly)
return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- if (pos.is_draw())
+ if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- if (ply >= PLY_MAX - 1)
- return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
-
// Mate distance pruning
if (value_mated_in(ply) >= beta)
return beta;
}
isCheck = pos.is_check();
- ei.futilityMargin = Value(0); // Manually initialize futilityMargin
-
- // Evaluate the position statically
- if (isCheck)
- staticValue = quick_evaluate(pos);
- else if (tte && (tte->type() & VALUE_TYPE_EVAL))
- staticValue = value_from_tt(tte->value(), ply);
- else
- staticValue = evaluate(pos, ei, threadID);
// Calculate depth dependant futility pruning parameters
const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8));
const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2);
- // Enhance score accuracy with TT value if possible
- ss[ply].eval = staticValue;
- futilityValue = staticValue + FutilityValueMargin;
- staticValue = refine_eval(tte, staticValue, ply);
+ // Evaluate the position statically
+ if (!isCheck)
+ {
+ if (tte && (tte->type() & VALUE_TYPE_EVAL))
+ staticValue = value_from_tt(tte->value(), ply);
+ else
+ {
+ staticValue = evaluate(pos, ei, threadID);
+ ss[ply].evalInfo = &ei;
+ }
+
+ ss[ply].eval = staticValue;
+ futilityValue = staticValue + FutilityValueMargin;
+ staticValue = refine_eval(tte, staticValue, ply); // Enhance accuracy with TT value if possible
+ }
// Null move search
if ( allowNullmove
}
// Null move search not allowed, try razoring
else if ( !value_is_mate(beta)
+ && !isCheck
&& depth < RazorDepth
- && staticValue < beta - (depth > OnePly ? NullMoveMargin + 16 * depth : 2*NullMoveMargin)
+ && staticValue < beta - (NullMoveMargin + 16 * depth)
&& ss[ply - 1].currentMove != MOVE_NULL
&& ttMove == MOVE_NONE
&& !pos.has_pawn_on_7th(pos.side_to_move()))
// Go with internal iterative deepening if we don't have a TT move
if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly &&
- !isCheck && evaluate(pos, ei, threadID) >= beta - IIDMargin)
+ !isCheck && ss[ply].eval >= beta - IIDMargin)
{
search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
ttMove = ss[ply].pv[ply];
// 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.
+ bool doFullDepthSearch = true;
+
if ( depth >= 3*OnePly
&& !dangerous
&& !captureOrPromotion
{
ss[ply].reduction = Depth(int(floor(red * int(OnePly))));
value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID);
+ doFullDepthSearch = (value >= beta);
}
- else
- value = beta; // Just to trigger next condition
}
- else
- value = beta; // Just to trigger next condition
- if (value >= beta) // Go with full depth non-pv search
+ if (doFullDepthSearch) // Go with full depth non-pv search
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
StateInfo st;
Move ttMove, move;
Value staticValue, bestValue, value, futilityBase, futilityValue;
- bool isCheck, enoughMaterial, moveIsCheck;
+ bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
const TTEntry* tte = NULL;
int moveCount = 0;
bool pvNode = (beta - alpha != 1);
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- if (pos.is_draw())
+ if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- if (ply >= PLY_MAX - 1)
- return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
-
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
tte = TT.retrieve(pos.get_key());
}
isCheck = pos.is_check();
- ei.futilityMargin = Value(0); // Manually initialize futilityMargin
// Evaluate the position statically
if (isCheck)
if (bestValue > alpha)
alpha = bestValue;
+ // If we are near beta then try to get a cutoff pushing checks a bit further
+ bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8;
+
// Initialize a MovePicker object for the current position, and prepare
- // to search the moves. Because the depth is <= 0 here, only captures,
- // queen promotions and checks (only if depth == 0) will be generated.
- MovePicker mp = MovePicker(pos, ttMove, depth, H);
+ // to search the moves. Because the depth is <= 0 here, only captures,
+ // queen promotions and checks (only if depth == 0 or depth == -OnePly
+ // and we are near beta) will be generated.
+ MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H);
CheckInfo ci(pos);
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin;
}
}
- // Don't search captures and checks with negative SEE values
- if ( !isCheck
+ // Detect blocking evasions that are candidate to be pruned
+ evasionPrunable = isCheck
+ && bestValue != -VALUE_INFINITE
+ && !pos.move_is_capture(move)
+ && pos.type_of_piece_on(move_from(move)) != KING
+ && !pos.can_castle(pos.side_to_move());
+
+ // Don't search moves with negative SEE values
+ if ( (!isCheck || evasionPrunable)
&& move != ttMove
&& !move_is_promotion(move)
&& pos.see_sign(move) < 0)
assert(threadID >= 0 && threadID < ActiveThreads);
assert(ActiveThreads > 1);
- Position pos = Position(sp->pos);
+ Position pos(*sp->pos);
CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
- Value value;
+ Value value = -VALUE_INFINITE;
Move move;
bool isCheck = pos.is_check();
bool useFutilityPruning = sp->depth < SelectiveDepth
&& !isCheck;
const int FutilityMoveCountMargin = 3 + (1 << (3 * int(sp->depth) / 8));
- const int FutilityValueMargin = 112 * bitScanReverse32(int(sp->depth) * int(sp->depth) / 2);
while ( sp->bestValue < sp->beta
&& !thread_should_stop(threadID)
continue;
// Value based pruning
- if (sp->futilityValue == VALUE_NONE)
- {
- EvalInfo ei;
- sp->futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
- }
-
Value futilityValueScaled = sp->futilityValue - moveCount * IncrementalFutilityMargin;
if (futilityValueScaled < sp->beta)
// 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.
+ bool doFullDepthSearch = true;
+
if ( !dangerous
&& !captureOrPromotion
&& !move_is_castle(move)
{
ss[sp->ply].reduction = Depth(int(floor(red * int(OnePly))));
value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
+ doFullDepthSearch = (value >= sp->beta);
}
- else
- value = sp->beta; // Just to trigger next condition
}
- else
- value = sp->beta; // Just to trigger next condition
- if (value >= sp->beta) // Go with full depth non-pv search
+ if (doFullDepthSearch) // Go with full depth non-pv search
{
ss[sp->ply].reduction = Depth(0);
value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID);
assert(threadID >= 0 && threadID < ActiveThreads);
assert(ActiveThreads > 1);
- Position pos = Position(sp->pos);
+ Position pos(*sp->pos);
CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
- Value value;
+ Value value = -VALUE_INFINITE;
Move move;
while ( sp->alpha < sp->beta
// 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.
+ bool doFullDepthSearch = true;
+
if ( !dangerous
&& !captureOrPromotion
&& !move_is_castle(move)
double red = 0.5 + ln(moveCount) * ln(sp->depth / 2) / 6.0;
if (red >= 1.0)
{
+ Value localAlpha = sp->alpha;
ss[sp->ply].reduction = Depth(int(floor(red * int(OnePly))));
- value = -search(pos, ss, -sp->alpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
+ value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
+ doFullDepthSearch = (value > localAlpha);
}
- else
- value = sp->alpha + 1; // Just to trigger next condition
}
- else
- value = sp->alpha + 1; // Just to trigger next condition
- if (value > sp->alpha) // Go with full depth non-pv search
+ if (doFullDepthSearch) // Go with full depth non-pv search
{
+ Value localAlpha = sp->alpha;
ss[sp->ply].reduction = Depth(0);
- value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true, threadID);
+ value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID);
- if (value > sp->alpha && value < sp->beta)
+ if (value > localAlpha && value < sp->beta)
{
// When the search fails high at ply 1 while searching the first
- // move at the root, set the flag failHighPly1. This is used for
+ // move at the root, set the flag failHighPly1. This is used for
// time managment: We don't want to stop the search early in
// such cases, because resolving the fail high at ply 1 could
// result in a big drop in score at the root.
if (sp->ply == 1 && RootMoveNumber == 1)
Threads[threadID].failHighPly1 = true;
- value = -search_pv(pos, ss, -sp->beta, -sp->alpha, newDepth, sp->ply+1, threadID);
+ // If another thread has failed high then sp->alpha has been increased
+ // to be higher or equal then beta, if so, avoid to start a PV search.
+ localAlpha = sp->alpha;
+ if (localAlpha < sp->beta)
+ value = -search_pv(pos, ss, -sp->beta, -localAlpha, newDepth, sp->ply+1, threadID);
+ else
+ assert(thread_should_stop(threadID));
+
Threads[threadID].failHighPly1 = false;
}
}
break;
// New best move?
- lock_grab(&(sp->lock));
- if (value > sp->bestValue && !thread_should_stop(threadID))
+ if (value > sp->bestValue) // Less then 2% of cases
{
- sp->bestValue = value;
- if (value > sp->alpha)
+ lock_grab(&(sp->lock));
+ if (value > sp->bestValue && !thread_should_stop(threadID))
{
- sp->alpha = value;
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- if (value == value_mate_in(sp->ply + 1))
- ss[sp->ply].mateKiller = move;
-
- if (value >= sp->beta)
+ sp->bestValue = value;
+ if (value > sp->alpha)
{
- for (int i = 0; i < ActiveThreads; i++)
- if (i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
+ // Ask threads to stop before to modify sp->alpha
+ if (value >= sp->beta)
+ {
+ for (int i = 0; i < ActiveThreads; i++)
+ if (i != threadID && (i == sp->master || sp->slaves[i]))
+ Threads[i].stop = true;
- sp->finished = true;
+ sp->finished = true;
+ }
+
+ sp->alpha = value;
+
+ sp_update_pv(sp->parentSstack, ss, sp->ply);
+ if (value == value_mate_in(sp->ply + 1))
+ ss[sp->ply].mateKiller = move;
}
- }
- // If we are at ply 1, and we are searching the first root move at
- // ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration.
- if ( sp->ply == 1
- && Iteration >= 2
- && -value <= IterationInfo[Iteration-1].value - ProblemMargin)
- Problem = true;
+ // If we are at ply 1, and we are searching the first root move at
+ // ply 0, set the 'Problem' variable if the score has dropped a lot
+ // (from the computer's point of view) since the previous iteration.
+ if ( sp->ply == 1
+ && Iteration >= 2
+ && -value <= IterationInfo[Iteration-1].value - ProblemMargin)
+ Problem = true;
+ }
+ lock_release(&(sp->lock));
}
- lock_release(&(sp->lock));
}
lock_grab(&(sp->lock));
// If this thread has been assigned work, launch a search
if (Threads[threadID].workIsWaiting)
{
+ assert(!Threads[threadID].idle);
+
Threads[threadID].workIsWaiting = false;
if (Threads[threadID].splitPoint->pvNode)
sp_search_pv(Threads[threadID].splitPoint, threadID);
if (!Threads[slave].idle || slave == master)
return false;
- if (Threads[slave].activeSplitPoints == 0)
+ // Make a local copy to be sure doesn't change under our feet
+ int localActiveSplitPoints = Threads[slave].activeSplitPoints;
+
+ if (localActiveSplitPoints == 0)
// No active split points means that the thread is available as
// a slave for any other thread.
return true;
if (ActiveThreads == 2)
return true;
- // Apply the "helpful master" concept if possible
- if (SplitPointStack[slave][Threads[slave].activeSplitPoints - 1].slaves[master])
+ // Apply the "helpful master" concept if possible. Use localActiveSplitPoints
+ // that is known to be > 0, instead of Threads[slave].activeSplitPoints that
+ // could have been set to 0 by another thread leading to an out of bound access.
+ if (SplitPointStack[slave][localActiveSplitPoints - 1].slaves[master])
return true;
return false;
assert(ActiveThreads > 1);
SplitPoint* splitPoint;
- int i;
lock_grab(&MPLock);
splitPoint = SplitPointStack[master] + Threads[master].activeSplitPoints;
Threads[master].activeSplitPoints++;
- // Initialize the split point object and copy current position
+ // Initialize the split point object
splitPoint->parent = Threads[master].splitPoint;
splitPoint->finished = false;
splitPoint->ply = ply;
splitPoint->mp = mp;
splitPoint->moves = *moves;
splitPoint->cpus = 1;
- splitPoint->pos.copy(p);
+ splitPoint->pos = &p;
splitPoint->parentSstack = sstck;
- for (i = 0; i < ActiveThreads; i++)
+ for (int i = 0; i < ActiveThreads; i++)
splitPoint->slaves[i] = 0;
- // Copy the current search stack to the master thread
- memcpy(splitPoint->sstack[master], sstck, (ply+1) * sizeof(SearchStack));
+ Threads[master].idle = false;
+ Threads[master].stop = false;
Threads[master].splitPoint = splitPoint;
- // Make copies of the current position and search stack for each thread
- for (i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++)
+ // Allocate available threads setting idle flag to false
+ for (int i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++)
if (thread_is_available(i, master))
{
- memcpy(splitPoint->sstack[i], sstck, (ply+1) * sizeof(SearchStack));
+ Threads[i].idle = false;
+ Threads[i].stop = false;
Threads[i].splitPoint = splitPoint;
splitPoint->slaves[i] = 1;
splitPoint->cpus++;
}
+ assert(splitPoint->cpus > 1);
+
+ // We can release the lock because master and slave threads are already booked
+ lock_release(&MPLock);
+
// Tell the threads that they have work to do. This will make them leave
- // their idle loop.
- for (i = 0; i < ActiveThreads; i++)
+ // their idle loop. But before copy search stack tail for each thread.
+ for (int i = 0; i < ActiveThreads; i++)
if (i == master || splitPoint->slaves[i])
{
- Threads[i].workIsWaiting = true;
- Threads[i].idle = false;
- Threads[i].stop = false;
+ memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 3 * sizeof(SearchStack));
+ Threads[i].workIsWaiting = true; // This makes the slave to exit from idle_loop()
}
- lock_release(&MPLock);
-
// Everything is set up. The master thread enters the idle loop, from
// which it will instantly launch a search, because its workIsWaiting
// slot is 'true'. We send the split point as a second parameter to the
projects / stockfish / blobdiff