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Try to prefetch as soon as position key is ready

Browse Source 
Move prefetching code inside do_move() so to allow a
very early prefetching and to put as many instructions
as possible between prefetching and following retrieve().

With this patch retrieve() times are cutted of another 25%

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-08-09 15:53:51 +01:00
parent cd4604b05c
commit 4251eac860
4 changed files with 74 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files

89
src/position.cpp
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@@ -34,6 +34,7 @@
#include "position.h"
#include "psqtab.h"
#include "san.h"
#include "tt.h"
#include "ucioption.h"
using std::string;
@@ -71,6 +72,14 @@ Position::Position(const string& fen) {
}
/// Position::setTranspositionTable() is used by search functions to pass
/// the pointer to the used TT so that do_move() will prefetch TT access.
void Position::setTranspositionTable(TranspositionTable* tt) {
TT = tt;
}
/// Position::from_fen() initializes the position object with the given FEN
/// string. This function is not very robust - make sure that input FENs are
/// correct (this is assumed to be the responsibility of the GUI).
@@ -743,6 +752,32 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
if (st->capture)
do_capture_move(st->capture, them, to);
// Update hash key
st->key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
st->key ^= zobSideToMove;
// Reset en passant square
if (st->epSquare != SQ_NONE)
{
st->key ^= zobEp[st->epSquare];
st->epSquare = SQ_NONE;
}
// Update castle rights, try to shortcut a common case
if ((castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES)
{
st->key ^= zobCastle[st->castleRights];
st->castleRights &= castleRightsMask[from];
st->castleRights &= castleRightsMask[to];
st->key ^= zobCastle[st->castleRights];
}
bool checkEpSquare = (pt == PAWN && abs(int(to) - int(from)) == 16);
// Prefetch TT access as soon as we know key is updated
if (!checkEpSquare && TT)
TT->prefetch(st->key);
// Move the piece
Bitboard move_bb = make_move_bb(from, to);
do_move_bb(&(byColorBB[us]), move_bb);
@@ -752,24 +787,6 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
board[to] = board[from];
board[from] = EMPTY;
// Update hash key
st->key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
// Update incremental scores
st->mgValue += pst_delta<MidGame>(piece, from, to);
st->egValue += pst_delta<EndGame>(piece, from, to);
// If the moving piece was a king, update the king square
if (pt == KING)
kingSquare[us] = to;
// Reset en passant square
if (st->epSquare != SQ_NONE)
{
st->key ^= zobEp[st->epSquare];
st->epSquare = SQ_NONE;
}
// If the moving piece was a pawn do some special extra work
if (pt == PAWN)
{
@@ -780,7 +797,7 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
// Set en passant square, only if moved pawn can be captured
if (abs(int(to) - int(from)) == 16)
if (checkEpSquare)
{
if ( (us == WHITE && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK)))
|| (us == BLACK && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE))))
@@ -791,19 +808,22 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
}
}
// Prefetch only here in the few cases we needed zobEp[] to update the key
if (checkEpSquare && TT)
TT->prefetch(st->key);
// Update incremental scores
st->mgValue += pst_delta<MidGame>(piece, from, to);
st->egValue += pst_delta<EndGame>(piece, from, to);
// If the moving piece was a king, update the king square
if (pt == KING)
kingSquare[us] = to;
// Update piece lists
pieceList[us][pt][index[from]] = to;
index[to] = index[from];
// Update castle rights, try to shortcut a common case
if ((castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES)
{
st->key ^= zobCastle[st->castleRights];
st->castleRights &= castleRightsMask[from];
st->castleRights &= castleRightsMask[to];
st->key ^= zobCastle[st->castleRights];
}
// Update checkers bitboard, piece must be already moved
st->checkersBB = EmptyBoardBB;
Square ksq = king_square(them);
@@ -820,7 +840,6 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
}
// Finish
st->key ^= zobSideToMove;
sideToMove = opposite_color(sideToMove);
gamePly++;
@@ -960,6 +979,8 @@ void Position::do_castle_move(Move m) {
// Update checkers BB
st->checkersBB = attacks_to(king_square(them), us);
st->key ^= zobSideToMove;
}
@@ -1050,6 +1071,8 @@ void Position::do_promotion_move(Move m) {
// Update checkers BB
st->checkersBB = attacks_to(king_square(them), us);
st->key ^= zobSideToMove;
}
@@ -1127,6 +1150,8 @@ void Position::do_ep_move(Move m) {
// Update checkers BB
st->checkersBB = attacks_to(king_square(them), us);
st->key ^= zobSideToMove;
}
@@ -1407,14 +1432,15 @@ void Position::do_null_move(StateInfo& backupSt) {
history[gamePly] = st->key;
// Update the necessary information
sideToMove = opposite_color(sideToMove);
if (st->epSquare != SQ_NONE)
st->key ^= zobEp[st->epSquare];
st->key ^= zobSideToMove;
TT->prefetch(st->key);
sideToMove = opposite_color(sideToMove);
st->epSquare = SQ_NONE;
st->rule50++;
gamePly++;
st->key ^= zobSideToMove;
st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
@@ -1654,6 +1680,7 @@ void Position::clear() {
initialKFile = FILE_E;
initialKRFile = FILE_H;
initialQRFile = FILE_A;
TT = NULL;
}