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Remove Stack/thread dependence in movepick

Browse source 
as a lower level routine, movepicker should not depend on the
search stack or the thread class, removing a circular dependency.
Instead of copying the search stack into the movepicker object,
as well as accessing the thread class for one of the histories,
pass the required fields explicitly to the constructor (removing
the need for thread.h and implicitly search.h in movepick.cpp).
The signature is thus longer, but more explicit:

Also some renaming of histories structures while there.

passed STC [-3,1], suggesting a small elo impact:

LLR: 3.13 (-2.94,2.94) [-3.00,1.00]
Total: 381053 W: 68071 L: 68551 D: 244431
elo =   -0.438 +-    0.660 LOS:    9.7%

No functional change.
This commit is contained in:
Joost VandeVondele 2017-06-30 17:20:00 +02:00 • committed by Marco Costalba
parent 53c2d9df5e
commit b40e45c1cc
5 changed files with 71 additions and 87 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

38
src/movepick.cpp
View file

@ -21,7 +21,6 @@
#include <cassert>
#include "movepick.h"
#include "thread.h"
namespace {
@ -67,23 +66,21 @@ namespace {
/// search captures, promotions, and some checks) and how important good move
/// ordering is at the current node.
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Search::Stack* s)
: pos(p), ss(s), depth(d) {
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
const PieceToHistory** ch, Move cm, Move* killers_p)
: pos(p), mainHistory(mh), contHistory(ch), countermove(cm),
killers{killers_p[0], killers_p[1]}, depth(d){
assert(d > DEPTH_ZERO);
Square prevSq = to_sq((ss-1)->currentMove);
countermove = pos.this_thread()->counterMoves[pos.piece_on(prevSq)][prevSq];
killers[0] = ss->killers[0];
killers[1] = ss->killers[1];
stage = pos.checkers() ? EVASION : MAIN_SEARCH;
ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
stage += (ttMove == MOVE_NONE);
}
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Square s)
: pos(p) {
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
const PieceToHistory** ch, Square s)
: pos(p), mainHistory(mh), contHistory(ch) {
assert(d <= DEPTH_ZERO);
@ -143,33 +140,22 @@ void MovePicker::score<CAPTURES>() {
template<>
void MovePicker::score<QUIETS>() {
const ButterflyHistory& history = pos.this_thread()->history;
const PieceToHistory& cmh = *(ss-1)->history;
const PieceToHistory& fmh = *(ss-2)->history;
const PieceToHistory& fm2 = *(ss-4)->history;
Color c = pos.side_to_move();
for (auto& m : *this)
m.value = cmh[pos.moved_piece(m)][to_sq(m)]
+ fmh[pos.moved_piece(m)][to_sq(m)]
+ fm2[pos.moved_piece(m)][to_sq(m)]
+ history[c][from_to(m)];
m.value = (*mainHistory)[pos.side_to_move()][from_to(m)]
+ (*contHistory[0])[pos.moved_piece(m)][to_sq(m)]
+ (*contHistory[1])[pos.moved_piece(m)][to_sq(m)]
+ (*contHistory[3])[pos.moved_piece(m)][to_sq(m)];
}
template<>
void MovePicker::score<EVASIONS>() {
// Try captures ordered by MVV/LVA, then non-captures ordered by stats heuristics
const ButterflyHistory& history = pos.this_thread()->history;
Color c = pos.side_to_move();
for (auto& m : *this)
if (pos.capture(m))
m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
- Value(type_of(pos.moved_piece(m))) + (1 << 28);
else
m.value = history[c][from_to(m)];
m.value = (*mainHistory)[pos.side_to_move()][from_to(m)];
}

43
src/movepick.h
View file

@ -49,14 +49,14 @@ typedef StatBoards<PIECE_NB, SQUARE_NB> PieceToBoards;
/// ordering decisions. It uses ButterflyBoards as backing store.
struct ButterflyHistory : public ButterflyBoards {
void update(Color c, Move m, int v) {
void update(Color c, Move m, int bonus) {
const int D = 324;
auto& entry = (*this)[c][from_to(m)];
assert(abs(v) <= D); // Consistency check for below formula
assert(abs(bonus) <= D); // Consistency check for below formula
entry += v * 32 - entry * abs(v) / D;
entry += bonus * 32 - entry * abs(bonus) / D;
assert(abs(entry) <= 32 * D);
}
@ -65,26 +65,27 @@ struct ButterflyHistory : public ButterflyBoards {
/// PieceToHistory is like ButterflyHistory, but is based on PieceToBoards
struct PieceToHistory : public PieceToBoards {
void update(Piece pc, Square to, int v) {
void update(Piece pc, Square to, int bonus) {
const int D = 936;
auto& entry = (*this)[pc][to];
assert(abs(v) <= D); // Consistency check for below formula
assert(abs(bonus) <= D); // Consistency check for below formula
entry += v * 32 - entry * abs(v) / D;
entry += bonus * 32 - entry * abs(bonus) / D;
assert(abs(entry) <= 32 * D);
}
};
/// CounterMoveStat stores counter moves indexed by [piece][to] of the previous
/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
/// move, see chessprogramming.wikispaces.com/Countermove+Heuristic
typedef StatBoards<PIECE_NB, SQUARE_NB, Move> CounterMoveStat;
typedef StatBoards<PIECE_NB, SQUARE_NB, Move> CounterMoveHistory;
/// CounterMoveHistoryStat is like CounterMoveStat but instead of a move it
/// stores a full history (based on PieceTo boards instead of ButterflyBoards).
typedef StatBoards<PIECE_NB, SQUARE_NB, PieceToHistory> CounterMoveHistoryStat;
/// ContinuationHistory is the history of a given pair of moves, usually the
/// current one given a previous one. History table is based on PieceToBoards
/// instead of ButterflyBoards.
typedef StatBoards<PIECE_NB, SQUARE_NB, PieceToHistory> ContinuationHistory;
/// MovePicker class is used to pick one pseudo legal move at a time from the
@ -93,17 +94,14 @@ typedef StatBoards<PIECE_NB, SQUARE_NB, PieceToHistory> CounterMoveHistoryStat;
/// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
/// beta algorithm, MovePicker attempts to return the moves which are most likely
/// to get a cut-off first.
namespace Search { struct Stack; }
class MovePicker {
public:
MovePicker(const MovePicker&) = delete;
MovePicker& operator=(const MovePicker&) = delete;
MovePicker(const Position&, Move, Value);
MovePicker(const Position&, Move, Depth, Square);
MovePicker(const Position&, Move, Depth, Search::Stack*);
MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const PieceToHistory**, Square);
MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const PieceToHistory**, Move, Move*);
Move next_move(bool skipQuiets = false);
private:
@ -112,15 +110,14 @@ private:
ExtMove* end() { return endMoves; }
const Position& pos;
const Search::Stack* ss;
Move killers[2];
Move countermove;
Depth depth;
Move ttMove;
const ButterflyHistory* mainHistory;
const PieceToHistory** contHistory;
Move ttMove, countermove, killers[2];
ExtMove *cur, *endMoves, *endBadCaptures;
int stage;
Square recaptureSquare;
Value threshold;
int stage;
ExtMove *cur, *endMoves, *endBadCaptures;
Depth depth;
ExtMove moves[MAX_MOVES];
};

69
src/search.cpp
View file

@ -151,7 +151,7 @@ namespace {
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
void update_pv(Move* pv, Move move, Move* childPv);
void update_cm_stats(Stack* ss, Piece pc, Square s, int bonus);
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);
} // namespace
@ -192,13 +192,13 @@ void Search::clear() {
for (Thread* th : Threads)
{
th->counterMoves.fill(MOVE_NONE);
th->history.fill(0);
th->mainHistory.fill(0);
for (auto& to : th->counterMoveHistory)
for (auto& to : th->contHistory)
for (auto& h : to)
h.fill(0);
th->counterMoveHistory[NO_PIECE][0].fill(CounterMovePruneThreshold - 1);
th->contHistory[NO_PIECE][0].fill(CounterMovePruneThreshold - 1);
}
Threads.main()->callsCnt = 0;
@ -334,7 +334,7 @@ void Thread::search() {
std::memset(ss-4, 0, 7 * sizeof(Stack));
for (int i = 4; i > 0; i--)
(ss-i)->history = &this->counterMoveHistory[NO_PIECE][0]; // Use as sentinel
(ss-i)->contHistory = &this->contHistory[NO_PIECE][0]; // Use as sentinel
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
@ -591,7 +591,7 @@ namespace {
assert(0 <= ss->ply && ss->ply < MAX_PLY);
ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
ss->history = &thisThread->counterMoveHistory[NO_PIECE][0];
ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
Square prevSq = to_sq((ss-1)->currentMove);
@ -623,14 +623,14 @@ namespace {
// Extra penalty for a quiet TT move in previous ply when it gets refuted
if ((ss-1)->moveCount == 1 && !pos.captured_piece())
update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
}
// Penalty for a quiet ttMove that fails low
else if (!pos.capture_or_promotion(ttMove))
{
int penalty = -stat_bonus(depth);
thisThread->history.update(pos.side_to_move(), ttMove, penalty);
update_cm_stats(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
thisThread->mainHistory.update(pos.side_to_move(), ttMove, penalty);
update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
}
}
return ttValue;
@ -734,7 +734,7 @@ namespace {
Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
ss->currentMove = MOVE_NULL;
ss->history = &thisThread->counterMoveHistory[NO_PIECE][0];
ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
pos.do_null_move(st);
Value nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)
@ -776,7 +776,7 @@ namespace {
if (pos.legal(move))
{
ss->currentMove = move;
ss->history = &thisThread->counterMoveHistory[pos.moved_piece(move)][to_sq(move)];
ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)];
assert(depth >= 5 * ONE_PLY);
pos.do_move(move, st);
@ -801,11 +801,10 @@ namespace {
moves_loop: // When in check search starts from here
const PieceToHistory& cmh = *(ss-1)->history;
const PieceToHistory& fmh = *(ss-2)->history;
const PieceToHistory& fm2 = *(ss-4)->history;
const PieceToHistory* contHist[] = { (ss-1)->contHistory, (ss-2)->contHistory, nullptr, (ss-4)->contHistory };
Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
MovePicker mp(pos, ttMove, depth, ss);
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, contHist, countermove, ss->killers);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
improving = ss->staticEval >= (ss-2)->staticEval
/* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */
@ -907,8 +906,8 @@ moves_loop: // When in check search starts from here
// Countermoves based pruning
if ( lmrDepth < 3
&& (cmh[moved_piece][to_sq(move)] < CounterMovePruneThreshold)
&& (fmh[moved_piece][to_sq(move)] < CounterMovePruneThreshold))
&& (*contHist[0])[moved_piece][to_sq(move)] < CounterMovePruneThreshold
&& (*contHist[1])[moved_piece][to_sq(move)] < CounterMovePruneThreshold)
continue;
// Futility pruning: parent node
@ -943,7 +942,7 @@ moves_loop: // When in check search starts from here
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
ss->history = &thisThread->counterMoveHistory[moved_piece][to_sq(move)];
ss->contHistory = &thisThread->contHistory[moved_piece][to_sq(move)];
// Step 14. Make the move
pos.do_move(move, st, givesCheck);
@ -975,11 +974,11 @@ moves_loop: // When in check search starts from here
&& !pos.see_ge(make_move(to_sq(move), from_sq(move))))
r -= 2 * ONE_PLY;
ss->statScore = cmh[moved_piece][to_sq(move)]
+ fmh[moved_piece][to_sq(move)]
+ fm2[moved_piece][to_sq(move)]
+ thisThread->history[~pos.side_to_move()][from_to(move)]
- 4000; // Correction factor
ss->statScore = thisThread->mainHistory[~pos.side_to_move()][from_to(move)]
+ (*contHist[0])[moved_piece][to_sq(move)]
+ (*contHist[1])[moved_piece][to_sq(move)]
+ (*contHist[3])[moved_piece][to_sq(move)]
- 4000;
// Decrease/increase reduction by comparing opponent's stat score
if (ss->statScore > 0 && (ss-1)->statScore < 0)
@ -1115,13 +1114,13 @@ moves_loop: // When in check search starts from here
// Extra penalty for a quiet TT move in previous ply when it gets refuted
if ((ss-1)->moveCount == 1 && !pos.captured_piece())
update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
}
// Bonus for prior countermove that caused the fail low
else if ( depth >= 3 * ONE_PLY
&& !pos.captured_piece()
&& is_ok((ss-1)->currentMove))
update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth));
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth));
if (!excludedMove)
tte->save(posKey, value_to_tt(bestValue, ss->ply),
@ -1241,7 +1240,8 @@ moves_loop: // When in check search starts from here
// to search the moves. Because the depth is <= 0 here, only captures,
// queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
// be generated.
MovePicker mp(pos, ttMove, depth, to_sq((ss-1)->currentMove));
const PieceToHistory* contHist[4] = {};
MovePicker mp(pos, ttMove, depth, &pos.this_thread()->mainHistory, contHist, to_sq((ss-1)->currentMove));
// Loop through the moves until no moves remain or a beta cutoff occurs
while ((move = mp.next_move()) != MOVE_NONE)
@ -1385,13 +1385,14 @@ moves_loop: // When in check search starts from here
}
// update_cm_stats() updates countermove and follow-up move history
// update_continuation_histories() updates histories of the move pairs formed
// by moves at ply -1, -2, and -4 with current move.
void update_cm_stats(Stack* ss, Piece pc, Square s, int bonus) {
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
for (int i : {1, 2, 4})
if (is_ok((ss-i)->currentMove))
(ss-i)->history->update(pc, s, bonus);
(ss-i)->contHistory->update(pc, to, bonus);
}
@ -1408,20 +1409,20 @@ moves_loop: // When in check search starts from here
Color c = pos.side_to_move();
Thread* thisThread = pos.this_thread();
thisThread->history.update(c, move, bonus);
update_cm_stats(ss, pos.moved_piece(move), to_sq(move), bonus);
thisThread->mainHistory.update(c, move, bonus);
update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus);
if (is_ok((ss-1)->currentMove))
{
Square prevSq = to_sq((ss-1)->currentMove);
thisThread->counterMoves[pos.piece_on(prevSq)][prevSq]=move;
thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move;
}
// Decrease all the other played quiet moves
for (int i = 0; i < quietsCnt; ++i)
{
thisThread->history.update(c, quiets[i], -bonus);
update_cm_stats(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
thisThread->mainHistory.update(c, quiets[i], -bonus);
update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
}

2
src/search.h
View file

@ -37,7 +37,7 @@ namespace Search {
struct Stack {
Move* pv;
PieceToHistory* history;
PieceToHistory* contHistory;
int ply;
Move currentMove;
Move excludedMove;

6
src/thread.h
View file

@ -67,9 +67,9 @@ public:
Search::RootMoves rootMoves;
Depth rootDepth;
Depth completedDepth;
CounterMoveStat counterMoves;
ButterflyHistory history;
CounterMoveHistoryStat counterMoveHistory;
CounterMoveHistory counterMoves;
ButterflyHistory mainHistory;
ContinuationHistory contHistory;
};