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Retire mate threat extension

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It seems we have a lot of totally useless code !

After 8577 games 1504 - 1451 - 5622 ELO +2 (+- 4.4)

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2011-04-08 07:48:05 +01:00
parent 9bee5f51d8
commit 8e71ee7ec6
5 changed files with 12 additions and 75 deletions
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40
src/position.cpp
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@@ -1689,46 +1689,6 @@ bool Position::is_mate() const {
}
/// Position::has_mate_threat() tests whether the side to move is under
/// a threat of being mated in one from the current position.
bool Position::has_mate_threat() {
MoveStack mlist[MOVES_MAX], *last, *cur;
StateInfo st1, st2;
bool mateFound = false;
// If we are under check it's up to evasions to do the job
if (is_check())
return false;
// First pass the move to our opponent doing a null move
do_null_move(st1);
// Then generate pseudo-legal moves that could give check
last = generate<MV_NON_CAPTURE_CHECK>(*this, mlist);
last = generate<MV_CAPTURE>(*this, last);
// Loop through the moves, and see if one of them gives mate
Bitboard pinned = pinned_pieces(sideToMove);
CheckInfo ci(*this);
for (cur = mlist; !mateFound && cur != last; cur++)
{
Move move = cur->move;
if ( !pl_move_is_legal(move, pinned)
|| !move_is_check(move, ci))
continue;
do_move(move, st2, ci, true);
mateFound = is_mate();
undo_move(move);
}
undo_null_move();
return mateFound;
}
/// Position::init_zobrist() is a static member function which initializes at
/// startup the various arrays used to compute hash keys.

3
src/position.h
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@@ -231,9 +231,6 @@ public:
bool is_mate() const;
bool is_draw() const;
// Check if side to move could be mated in one
bool has_mate_threat();
// Number of plies from starting position
int startpos_ply_counter() const;

36
src/search.cpp
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@@ -80,7 +80,7 @@ namespace {
template <bool Fake>
void split(Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue,
Depth depth, Move threatMove, bool mateThreat, int moveCount, MovePicker* mp, bool pvNode);
Depth depth, Move threatMove, int moveCount, MovePicker* mp, bool pvNode);
private:
Depth minimumSplitDepth;
@@ -192,8 +192,8 @@ namespace {
// Extensions. Configurable UCI options
// Array index 0 is used at non-PV nodes, index 1 at PV nodes.
Depth CheckExtension[2], PawnPushTo7thExtension[2], PassedPawnExtension[2];
Depth PawnEndgameExtension[2], MateThreatExtension[2];
Depth CheckExtension[2], PawnPushTo7thExtension[2];
Depth PassedPawnExtension[2], PawnEndgameExtension[2];
// Minimum depth for use of singular extension
const Depth SingularExtensionDepth[2] = { 8 * ONE_PLY /* non-PV */, 6 * ONE_PLY /* PV */};
@@ -280,7 +280,7 @@ namespace {
}
template <NodeType PvNode>
Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool mateThreat, bool* dangerous);
Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool* dangerous);
bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue);
bool connected_moves(const Position& pos, Move m1, Move m2);
@@ -484,8 +484,6 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[
PassedPawnExtension[0] = Options["Passed Pawn Extension (non-PV nodes)"].value<Depth>();
PawnEndgameExtension[1] = Options["Pawn Endgame Extension (PV nodes)"].value<Depth>();
PawnEndgameExtension[0] = Options["Pawn Endgame Extension (non-PV nodes)"].value<Depth>();
MateThreatExtension[1] = Options["Mate Threat Extension (PV nodes)"].value<Depth>();
MateThreatExtension[0] = Options["Mate Threat Extension (non-PV nodes)"].value<Depth>();
UCIMultiPV = Options["MultiPV"].value<int>();
SkillLevel = Options["Skill level"].value<int>();
UseLogFile = Options["Use Search Log"].value<bool>();
@@ -792,7 +790,6 @@ namespace {
Value bestValue, value, oldAlpha;
Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous, isBadCap;
bool mateThreat = false;
int moveCount = 0, playedMoveCount = 0;
int threadID = pos.thread();
SplitPoint* sp = NULL;
@@ -807,7 +804,6 @@ namespace {
tte = NULL;
ttMove = excludedMove = MOVE_NONE;
threatMove = sp->threatMove;
mateThreat = sp->mateThreat;
goto split_point_start;
}
else if (Root)
@@ -957,9 +953,6 @@ namespace {
// move which was reduced. If a connection is found, return a fail
// low score (which will cause the reduced move to fail high in the
// parent node, which will trigger a re-search with full depth).
if (nullValue == value_mated_in(ply + 2))
mateThreat = true;
threatMove = (ss+1)->bestMove;
if ( depth < ThreatDepth
@@ -985,10 +978,6 @@ namespace {
tte = TT.retrieve(posKey);
}
// Mate threat detection for PV nodes, otherwise we use null move search
if (PvNode)
mateThreat = pos.has_mate_threat();
split_point_start: // At split points actual search starts from here
// Initialize a MovePicker object for the current position
@@ -1055,7 +1044,7 @@ split_point_start: // At split points actual search starts from here
captureOrPromotion = pos.move_is_capture_or_promotion(move);
// Step 11. Decide the new search depth
ext = extension<PvNode>(pos, move, captureOrPromotion, moveIsCheck, mateThreat, &dangerous);
ext = extension<PvNode>(pos, move, captureOrPromotion, moveIsCheck, &dangerous);
// Singular extension search. If all moves but one fail low on a search of
// (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
@@ -1309,7 +1298,7 @@ split_point_start: // At split points actual search starts from here
&& !StopRequest
&& !ThreadsMgr.cutoff_at_splitpoint(threadID))
ThreadsMgr.split<FakeSplit>(pos, ss, ply, &alpha, beta, &bestValue, depth,
threatMove, mateThreat, moveCount, &mp, PvNode);
threatMove, moveCount, &mp, PvNode);
}
// Step 19. Check for mate and stalemate
@@ -1696,22 +1685,16 @@ split_point_start: // At split points actual search starts from here
// the move is marked as 'dangerous' so, at least, we avoid to prune it.
template <NodeType PvNode>
Depth extension(const Position& pos, Move m, bool captureOrPromotion,
bool moveIsCheck, bool mateThreat, bool* dangerous) {
bool moveIsCheck, bool* dangerous) {
assert(m != MOVE_NONE);
Depth result = DEPTH_ZERO;
*dangerous = moveIsCheck | mateThreat;
*dangerous = moveIsCheck;
if (*dangerous)
{
if (moveIsCheck && pos.see_sign(m) >= 0)
result += CheckExtension[PvNode];
if (mateThreat)
result += MateThreatExtension[PvNode];
}
if (pos.type_of_piece_on(move_from(m)) == PAWN)
{
Color c = pos.side_to_move();
@@ -2311,7 +2294,7 @@ split_point_start: // At split points actual search starts from here
template <bool Fake>
void ThreadsManager::split(Position& pos, SearchStack* ss, int ply, Value* alpha,
const Value beta, Value* bestValue, Depth depth, Move threatMove,
bool mateThreat, int moveCount, MovePicker* mp, bool pvNode) {
int moveCount, MovePicker* mp, bool pvNode) {
assert(pos.is_ok());
assert(ply > 0 && ply < PLY_MAX);
assert(*bestValue >= -VALUE_INFINITE);
@@ -2346,7 +2329,6 @@ split_point_start: // At split points actual search starts from here
splitPoint.ply = ply;
splitPoint.depth = depth;
splitPoint.threatMove = threatMove;
splitPoint.mateThreat = mateThreat;
splitPoint.alpha = *alpha;
splitPoint.beta = beta;
splitPoint.pvNode = pvNode;

2
src/thread.h
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@@ -36,7 +36,7 @@ struct SplitPoint {
SplitPoint* parent;
const Position* pos;
Depth depth;
bool pvNode, mateThreat;
bool pvNode;
Value beta;
int ply;
int master;

2
src/ucioption.cpp
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@@ -81,8 +81,6 @@ void init_uci_options() {
Options["Cowardice"] = Option(100, 0, 200);
Options["Check Extension (PV nodes)"] = Option(2, 0, 2);
Options["Check Extension (non-PV nodes)"] = Option(1, 0, 2);
Options["Mate Threat Extension (PV nodes)"] = Option(2, 0, 2);
Options["Mate Threat Extension (non-PV nodes)"] = Option(2, 0, 2);
Options["Pawn Push to 7th Extension (PV nodes)"] = Option(1, 0, 2);
Options["Pawn Push to 7th Extension (non-PV nodes)"] = Option(1, 0, 2);
Options["Passed Pawn Extension (PV nodes)"] = Option(1, 0, 2);