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Use extendable instead of depth extension

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We can have depth(0) also in problematic cases
according to how extensions are tweaked by the user.

In any case we don't want to prune these moves.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2008-11-24 17:50:54 +01:00
parent 8a0dd93c56
commit ee9f650242
1 changed files with 36 additions and 20 deletions
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56
src/search.cpp
View file

@ -245,7 +245,7 @@ namespace {
void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply);
bool connected_moves(const Position &pos, Move m1, Move m2);
bool move_is_killer(Move m, const SearchStack& ss);
Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat);
Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat, bool* extendable);
bool ok_to_do_nullmove(const Position &pos);
bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d);
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
@ -778,7 +778,8 @@ namespace {
<< " currmovenumber " << i + 1 << std::endl;
// Decide search depth for this move
ext = extension(pos, move, true, pos.move_is_check(move), false, false);
bool dummy;
ext = extension(pos, move, true, pos.move_is_check(move), false, false, &dummy);
newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
// Make the move, and search it
@ -978,7 +979,8 @@ namespace {
ss[ply].currentMoveCaptureValue = Value(0);
// Decide the new search depth
Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat);
bool extendable;
Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat, &extendable);
Depth newDepth = depth - OnePly + ext;
// Make and search the move
@ -992,7 +994,7 @@ namespace {
// 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.
if ( depth >= 2*OnePly
&& ext == Depth(0)
&& !extendable
&& moveCount >= LMRPVMoves
&& !moveIsCapture
&& !move_promotion(move)
@ -1225,12 +1227,13 @@ namespace {
movesSearched[moveCount++] = ss[ply].currentMove = move;
// Decide the new search depth
Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat);
bool extendable;
Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat, &extendable);
Depth newDepth = depth - OnePly + ext;
// Futility pruning
if ( useFutilityPruning
&& ext == Depth(0)
&& !extendable
&& !moveIsCapture
&& !moveIsPassedPawnPush
&& !move_promotion(move))
@ -1261,7 +1264,7 @@ namespace {
// 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.
if ( depth >= 2*OnePly
&& ext == Depth(0)
&& !extendable
&& moveCount >= LMRNonPVMoves
&& !moveIsCapture
&& !move_promotion(move)
@ -1515,12 +1518,13 @@ namespace {
ss[sp->ply].currentMove = move;
// Decide the new search depth.
Depth ext = extension(pos, move, false, moveIsCheck, false, false);
bool extendable;
Depth ext = extension(pos, move, false, moveIsCheck, false, false, &extendable);
Depth newDepth = sp->depth - OnePly + ext;
// Prune?
if ( useFutilityPruning
&& ext == Depth(0)
&& !extendable
&& !moveIsCapture
&& !moveIsPassedPawnPush
&& !move_promotion(move)
@ -1534,7 +1538,7 @@ namespace {
// 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.
if ( ext == Depth(0)
if ( !extendable
&& moveCount >= LMRNonPVMoves
&& !moveIsCapture
&& !moveIsPassedPawnPush
@ -1632,7 +1636,8 @@ namespace {
ss[sp->ply].currentMove = move;
// Decide the new search depth.
Depth ext = extension(pos, move, true, moveIsCheck, false, false);
bool extendable;
Depth ext = extension(pos, move, true, moveIsCheck, false, false, &extendable);
Depth newDepth = sp->depth - OnePly + ext;
// Make and search the move.
@ -1641,7 +1646,7 @@ namespace {
// 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.
if ( ext == Depth(0)
if ( !extendable
&& moveCount >= LMRPVMoves
&& !moveIsCapture
&& !moveIsPassedPawnPush
@ -1923,7 +1928,6 @@ namespace {
NodesSincePoll = 0;
}
}
ss[ply].pv[ply] = ss[ply].pv[ply+1] = ss[ply].currentMove = MOVE_NONE;
ss[ply+2].mateKiller = MOVE_NONE;
ss[ply].threatMove = MOVE_NONE;
@ -2052,9 +2056,10 @@ namespace {
// particular) are searched with bigger depth than ordinary moves.
Depth extension(const Position &pos, Move m, bool pvNode,
bool check, bool singleReply, bool mateThreat) {
bool check, bool singleReply, bool mateThreat, bool* extendable) {
Depth result = Depth(0);
*extendable = check || singleReply || mateThreat;
if (check)
result += CheckExtension[pvNode];
@ -2062,26 +2067,37 @@ namespace {
if (singleReply)
result += SingleReplyExtension[pvNode];
if (pos.move_is_pawn_push_to_7th(m))
result += PawnPushTo7thExtension[pvNode];
if (pos.move_is_passed_pawn_push(m))
result += PassedPawnExtension[pvNode];
if (mateThreat)
result += MateThreatExtension[pvNode];
if (pos.move_is_pawn_push_to_7th(m))
{
result += PawnPushTo7thExtension[pvNode];
*extendable = true;
}
if (pos.move_is_passed_pawn_push(m))
{
result += PassedPawnExtension[pvNode];
*extendable = true;
}
if ( pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame
&& ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- pos.midgame_value_of_piece_on(move_to(m)) == Value(0))
&& !move_promotion(m))
{
result += PawnEndgameExtension[pvNode];
*extendable = true;
}
if ( pvNode
&& pos.move_is_capture(m)
&& pos.type_of_piece_on(move_to(m)) != PAWN
&& pos.see(m) >= 0)
{
result += OnePly/2;
*extendable = true;
}
return Min(result, OnePly);
}