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In qsearch store the cut move in TT

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And upon reentering the same position try it as first.

Normally qsearch moves order is already very good, first move
is the cut off in almost 90% of cases. With this patch, we get
a cut off on TT move of 98%.

Another good side effect is that we don't generate captures
and/or checks when we already have a TT move.

Unfortunatly we found a TT move only in 1% of cases. So real
impact of this patch is relatively low.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-04-18 14:03:33 +01:00
parent 4634be8ba6
commit e68ebe618c
3 changed files with 14 additions and 25 deletions
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27
src/movepick.cpp
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@@ -50,7 +50,6 @@ namespace {
}
////
//// Functions
////
@@ -445,9 +444,9 @@ Move MovePicker::pick_move_from_list() {
bestIndex = (movesPicked < 4 ? find_best_index() : movesPicked);
move = moves[bestIndex].move;
moves[bestIndex] = moves[movesPicked++];
// Remember to change the line below if we decide to hash the qsearch!
// Maybe also postpone the legality check until after futility pruning?
if (/* move != ttMove && */ pos.pl_move_is_legal(move, pinned))
// Maybe postpone the legality check until after futility pruning?
if ( move != ttMove
&& pos.pl_move_is_legal(move, pinned))
return move;
}
break;
@@ -460,8 +459,8 @@ Move MovePicker::pick_move_from_list() {
while (movesPicked < numOfMoves)
{
move = moves[movesPicked++].move;
// Remember to change the line below if we decide to hash the qsearch!
if (/* move != ttMove && */ pos.pl_move_is_legal(move, pinned))
if ( move != ttMove
&& pos.pl_move_is_legal(move, pinned))
return move;
}
break;
@@ -473,20 +472,10 @@ Move MovePicker::pick_move_from_list() {
}
/// MovePicker::current_move_type() returns the type of the just
/// picked next move. It can be used in search to further differentiate
/// according to the current move type: capture, non capture, escape, etc.
MovePicker::MovegenPhase MovePicker::current_move_type() const {
return PhaseTable[phaseIndex];
}
/// MovePicker::init_phase_table() initializes the PhaseTable[],
/// MainSearchPhaseIndex, EvasionPhaseIndex, QsearchWithChecksPhaseIndex
/// QsearchNoCapturesPhaseIndex, QsearchWithoutChecksPhaseIndex and
/// NoMovesPhaseIndex variables. It is only called once during program
/// startup, and never again while the program is running.
/// and QsearchWithoutChecksPhaseIndex. It is only called once during
/// program startup, and never again while the program is running.
void MovePicker::init_phase_table() {
@@ -511,12 +500,14 @@ void MovePicker::init_phase_table() {
// Quiescence search with checks
QsearchWithChecksPhaseIndex = i - 1;
PhaseTable[i++] = PH_TT_MOVE;
PhaseTable[i++] = PH_QCAPTURES;
PhaseTable[i++] = PH_QCHECKS;
PhaseTable[i++] = PH_STOP;
// Quiescence search without checks
QsearchWithoutChecksPhaseIndex = i - 1;
PhaseTable[i++] = PH_TT_MOVE;
PhaseTable[i++] = PH_QCAPTURES;
PhaseTable[i++] = PH_STOP;