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Merge Stats tables
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Use a recursive std::array with variadic template
parameters to get rid of the last redundacy.

The first template T parameter is the base type of
the array, the W parameter is the weight applied to
the bonuses when we update values with the << operator,
the D parameter limits the range of updates (range is
[-W * D, W * D]), and the last parameters (Size and
Sizes) encode the dimensions of the array.

This allows greater flexibility because we can now tweak
the range [-W * D, W * D] for each table.

Patch removes more lines than what adds and streamlines
the Stats soup in movepick.h

Closes PR#1422 and PR#1421

No functional change.
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@mcostalba @snicolet
mcostalba authored and snicolet committed Mar 3, 2018
1 parent 94b3cdd commit f35e52f
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Showing 4 changed files with 63 additions and 74 deletions.
2 changes: 1 addition & 1 deletion src/movepick.cpp
View file
Expand Up @@ -127,7 +127,7 @@ void MovePicker::score() {
for (auto& m : *this)
if (Type == CAPTURES)
m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
+ Value((*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))]);
+ (*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))];

else if (Type == QUIETS)
m.value = (*mainHistory)[pos.side_to_move()][from_to(m)]
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109 changes: 49 additions & 60 deletions src/movepick.h
View file
Expand Up @@ -23,95 +23,84 @@

#include <array>
#include <limits>
#include <type_traits>

#include "movegen.h"
#include "position.h"
#include "types.h"

/// StatBoards is a generic 2-dimensional array used to store various statistics
template<int Size1, int Size2, typename T = int16_t>
struct StatBoards : public std::array<std::array<T, Size2>, Size1> {
/// StatsEntry stores the stat table value. It is usually a number but could
/// be a move or even a nested history. We use a class instead of naked value
/// to directly call history update operator<<() on the entry so to use stats
/// tables at caller sites as simple multi-dim arrays.
template<typename T, int W, int D>
class StatsEntry {

void fill(const T& v) {
T* p = &(*this)[0][0];
std::fill(p, p + sizeof(*this) / sizeof(*p), v);
}

void update(T& entry, int bonus, const int D) {

assert(abs(bonus) <= D); // Ensure range is [-32 * D, 32 * D]
assert(abs(32 * D) < (std::numeric_limits<T>::max)()); // Ensure we don't overflow

entry += bonus * 32 - entry * abs(bonus) / D;

assert(abs(entry) <= 32 * D);
}
};
static const bool IsInt = std::is_integral<T>::value;
typedef typename std::conditional<IsInt, int, T>::type TT;

/// StatCubes is a generic 3-dimensional array used to store various statistics
template<int Size1, int Size2, int Size3, typename T = int16_t>
struct StatCubes : public std::array<std::array<std::array<T, Size3>, Size2>, Size1> {
T entry;

void fill(const T& v) {
T* p = &(*this)[0][0][0];
std::fill(p, p + sizeof(*this) / sizeof(*p), v);
}
public:
T* get() { return &entry; }
void operator=(const T& v) { entry = v; }
operator TT() const { return entry; }

void update(T& entry, int bonus, const int D, const int W) {
void operator<<(int bonus) {

assert(abs(bonus) <= D); // Ensure range is [-W * D, W * D]
assert(abs(W * D) < (std::numeric_limits<T>::max)()); // Ensure we don't overflow
assert(abs(W * D) < std::numeric_limits<T>::max()); // Ensure we don't overflow

entry += bonus * W - entry * abs(bonus) / D;

assert(abs(entry) <= W * D);
}
};

/// ButterflyBoards are 2 tables (one for each color) indexed by the move's from
/// and to squares, see chessprogramming.wikispaces.com/Butterfly+Boards
typedef StatBoards<COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyBoards;

/// PieceToBoards are addressed by a move's [piece][to] information
typedef StatBoards<PIECE_NB, SQUARE_NB> PieceToBoards;
/// Stats is a generic N-dimensional array used to store various statistics.
/// The first template T parameter is the base type of the array, the W parameter
/// is the weight applied to the bonuses when we update values with the << operator,
/// the D parameter limits the range of updates (range is [-W * D, W * D]), and
/// the last parameters (Size and Sizes) encode the dimensions of the array.
template <typename T, int W, int D, int Size, int... Sizes>
struct Stats : public std::array<Stats<T, W, D, Sizes...>, Size>
{
T* get() { return this->at(0).get(); }

/// CapturePieceToBoards are addressed by a move's [piece][to][captured piece type] information
typedef StatCubes<PIECE_NB, SQUARE_NB, PIECE_TYPE_NB> CapturePieceToBoards;

/// ButterflyHistory records how often quiet moves have been successful or
/// unsuccessful during the current search, and is used for reduction and move
/// ordering decisions. It uses ButterflyBoards as backing store.
struct ButterflyHistory : public ButterflyBoards {

void update(Color c, Move m, int bonus) {
StatBoards::update((*this)[c][from_to(m)], bonus, 324);
void fill(const T& v) {
T* p = get();
std::fill(p, p + sizeof(*this) / sizeof(*p), v);
}
};

/// PieceToHistory is like ButterflyHistory, but is based on PieceToBoards
struct PieceToHistory : public PieceToBoards {

void update(Piece pc, Square to, int bonus) {
StatBoards::update((*this)[pc][to], bonus, 936);
}
template <typename T, int W, int D, int Size>
struct Stats<T, W, D, Size> : public std::array<StatsEntry<T, W, D>, Size> {
T* get() { return this->at(0).get(); }
};

/// CapturePieceToHistory is like PieceToHistory, but is based on CapturePieceToBoards
struct CapturePieceToHistory : public CapturePieceToBoards {
/// Different tables use different W/D parameter, name them to ease readibility
enum StatsParams { W2 = 2, W32 = 32, D324 = 324, D936 = 936, NOT_USED = 0 };

void update(Piece pc, Square to, PieceType captured, int bonus) {
StatCubes::update((*this)[pc][to][captured], bonus, 324, 2);
}
};
/// ButterflyHistory records how often quiet moves have been successful or
/// unsuccessful during the current search, and is used for reduction and move
/// ordering decisions. It uses 2 tables (one for each color) indexed by
/// the move's from and to squares, see chessprogramming.wikispaces.com/Butterfly+Boards
typedef Stats<int16_t, W32, D324, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;

/// 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> CounterMoveHistory;
typedef Stats<Move, NOT_USED, NOT_USED, PIECE_NB, SQUARE_NB> CounterMoveHistory;

/// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
typedef Stats<int16_t, W2, D324, PIECE_NB, SQUARE_NB, PIECE_TYPE_NB> CapturePieceToHistory;

/// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to]
typedef Stats<int16_t, W32, D936, PIECE_NB, SQUARE_NB> PieceToHistory;

/// 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;
/// ContinuationHistory is the combined history of a given pair of moves, usually
/// the current one given a previous one. The nested history table is based on
/// PieceToHistory instead of ButterflyBoards.
typedef Stats<PieceToHistory, W32, NOT_USED, PIECE_NB, SQUARE_NB> ContinuationHistory;


/// MovePicker class is used to pick one pseudo legal move at a time from the
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22 changes: 11 additions & 11 deletions src/search.cpp
View file
Expand Up @@ -289,7 +289,7 @@ void Thread::search() {

std::memset(ss-4, 0, 7 * sizeof(Stack));
for (int i = 4; i > 0; i--)
(ss-i)->contHistory = &this->contHistory[NO_PIECE][0]; // Use as sentinel
(ss-i)->contHistory = this->contHistory[NO_PIECE][0].get(); // Use as sentinel

bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
Expand Down Expand Up @@ -550,7 +550,7 @@ namespace {

(ss+1)->ply = ss->ply + 1;
ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
ss->contHistory = thisThread->contHistory[NO_PIECE][0].get();
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
Square prevSq = to_sq((ss-1)->currentMove);

Expand Down Expand Up @@ -595,7 +595,7 @@ namespace {
else if (!pos.capture_or_promotion(ttMove))
{
int penalty = -stat_bonus(depth);
thisThread->mainHistory.update(pos.side_to_move(), ttMove, penalty);
thisThread->mainHistory[pos.side_to_move()][from_to(ttMove)] << penalty;
update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
}
}
Expand Down Expand Up @@ -715,7 +715,7 @@ namespace {
Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;

ss->currentMove = MOVE_NULL;
ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
ss->contHistory = thisThread->contHistory[NO_PIECE][0].get();

pos.do_null_move(st);
Value nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)
Expand Down Expand Up @@ -762,7 +762,7 @@ namespace {
if (pos.legal(move))
{
ss->currentMove = move;
ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)];
ss->contHistory = thisThread->contHistory[pos.moved_piece(move)][to_sq(move)].get();

assert(depth >= 5 * ONE_PLY);

Expand Down Expand Up @@ -937,7 +937,7 @@ namespace {

// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
ss->contHistory = &thisThread->contHistory[movedPiece][to_sq(move)];
ss->contHistory = thisThread->contHistory[movedPiece][to_sq(move)].get();

// Step 15. Make the move
pos.do_move(move, st, givesCheck);
Expand Down Expand Up @@ -1401,7 +1401,7 @@ namespace {

for (int i : {1, 2, 4})
if (is_ok((ss-i)->currentMove))
(ss-i)->contHistory->update(pc, to, bonus);
(*(ss-i)->contHistory)[pc][to] << bonus;
}


Expand All @@ -1413,14 +1413,14 @@ namespace {
CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory;
Piece moved_piece = pos.moved_piece(move);
PieceType captured = type_of(pos.piece_on(to_sq(move)));
captureHistory.update(moved_piece, to_sq(move), captured, bonus);
captureHistory[moved_piece][to_sq(move)][captured] << bonus;

// Decrease all the other played capture moves
for (int i = 0; i < captureCnt; ++i)
{
moved_piece = pos.moved_piece(captures[i]);
captured = type_of(pos.piece_on(to_sq(captures[i])));
captureHistory.update(moved_piece, to_sq(captures[i]), captured, -bonus);
captureHistory[moved_piece][to_sq(captures[i])][captured] << -bonus;
}
}

Expand All @@ -1438,7 +1438,7 @@ namespace {

Color us = pos.side_to_move();
Thread* thisThread = pos.this_thread();
thisThread->mainHistory.update(us, move, bonus);
thisThread->mainHistory[us][from_to(move)] << bonus;
update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus);

if (is_ok((ss-1)->currentMove))
Expand All @@ -1450,7 +1450,7 @@ namespace {
// Decrease all the other played quiet moves
for (int i = 0; i < quietsCnt; ++i)
{
thisThread->mainHistory.update(us, quiets[i], -bonus);
thisThread->mainHistory[us][from_to(quiets[i])] << -bonus;
update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
}
Expand Down
4 changes: 2 additions & 2 deletions src/thread.cpp
View file
Expand Up @@ -62,9 +62,9 @@ void Thread::clear() {

for (auto& to : contHistory)
for (auto& h : to)
h.fill(0);
h.get()->fill(0);

contHistory[NO_PIECE][0].fill(Search::CounterMovePruneThreshold - 1);
contHistory[NO_PIECE][0].get()->fill(Search::CounterMovePruneThreshold - 1);
}

/// Thread::start_searching() wakes up the thread that will start the search
Expand Down

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