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Space inflate search()

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Same as previous patch but for search() function.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2008-09-06 18:25:58 +02:00
parent b7781e8faa
commit d517080ab6
1 changed files with 168 additions and 135 deletions
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src/search.cpp
+168 -135
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@@ -242,6 +242,7 @@ namespace {
bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d); 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); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
bool fail_high_ply_1(); bool fail_high_ply_1();
int current_search_time(); int current_search_time();
int nps(); int nps();
@@ -865,7 +866,7 @@ namespace {
Move ttMove = (tte ? tte->move() : MOVE_NONE); Move ttMove = (tte ? tte->move() : MOVE_NONE);
// Go with internal iterative deepening if we don't have a TT move. // Go with internal iterative deepening if we don't have a TT move
if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly) if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly)
{ {
search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID); search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
@@ -902,11 +903,11 @@ namespace {
ss[ply].currentMoveCaptureValue = move_is_ep(move) ? ss[ply].currentMoveCaptureValue = move_is_ep(move) ?
PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
// Decide the new search depth. // Decide the new search depth
Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat); Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat);
Depth newDepth = depth - OnePly + ext; Depth newDepth = depth - OnePly + ext;
// Make and search the move. // Make and search the move
UndoInfo u; UndoInfo u;
pos.do_move(move, u, dcCandidates); pos.do_move(move, u, dcCandidates);
@@ -976,9 +977,12 @@ namespace {
// Split? // Split?
if ( ActiveThreads > 1 if ( ActiveThreads > 1
&& bestValue < beta && depth >= MinimumSplitDepth && bestValue < beta
&& Iteration <= 99 && idle_thread_exists(threadID) && depth >= MinimumSplitDepth
&& !AbortSearch && !thread_should_stop(threadID) && Iteration <= 99
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
&& split(pos, ss, ply, &alpha, &beta, &bestValue, depth, && split(pos, ss, ply, &alpha, &beta, &bestValue, depth,
&moveCount, &mp, dcCandidates, threadID, true)) &moveCount, &mp, dcCandidates, threadID, true))
break; break;
@@ -1003,10 +1007,10 @@ namespace {
Move m = ss[ply].pv[ply]; Move m = ss[ply].pv[ply];
if (pos.square_is_empty(move_to(m)) && !move_promotion(m) && !move_is_ep(m)) if (pos.square_is_empty(move_to(m)) && !move_promotion(m) && !move_is_ep(m))
{ {
for(int i = 0; i < moveCount - 1; i++) for (int i = 0; i < moveCount - 1; i++)
if( pos.square_is_empty(move_to(movesSearched[i])) if ( pos.square_is_empty(move_to(movesSearched[i]))
&& !move_promotion(movesSearched[i]) && !move_promotion(movesSearched[i])
&& !move_is_ep(movesSearched[i])) && !move_is_ep(movesSearched[i]))
H.failure(pos.piece_on(move_from(movesSearched[i])), movesSearched[i]); H.failure(pos.piece_on(move_from(movesSearched[i])), movesSearched[i]);
H.success(pos.piece_on(move_from(m)), m, depth); H.success(pos.piece_on(move_from(m)), m, depth);
@@ -1030,6 +1034,7 @@ namespace {
Value search(Position &pos, SearchStack ss[], Value beta, Depth depth, Value search(Position &pos, SearchStack ss[], Value beta, Depth depth,
int ply, bool allowNullmove, int threadID) { int ply, bool allowNullmove, int threadID) {
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX); assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads); assert(threadID >= 0 && threadID < ActiveThreads);
@@ -1038,25 +1043,25 @@ namespace {
// Initialize, and make an early exit in case of an aborted search, // Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc. // an instant draw, maximum ply reached, etc.
if(AbortSearch || thread_should_stop(threadID)) if (AbortSearch || thread_should_stop(threadID))
return Value(0); return Value(0);
if(depth < OnePly) if (depth < OnePly)
return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
init_node(pos, ss, ply, threadID); init_node(pos, ss, ply, threadID);
if(pos.is_draw()) if (pos.is_draw())
return VALUE_DRAW; return VALUE_DRAW;
if(ply >= PLY_MAX - 1) if (ply >= PLY_MAX - 1)
return evaluate(pos, ei, threadID); return evaluate(pos, ei, threadID);
// Mate distance pruning // Mate distance pruning
if(value_mated_in(ply) >= beta) if (value_mated_in(ply) >= beta)
return beta; return beta;
if(value_mate_in(ply+1) < beta) if (value_mate_in(ply + 1) < beta)
return beta-1; return beta - 1;
// Transposition table lookup // Transposition table lookup
const TTEntry* tte = TT.retrieve(pos); const TTEntry* tte = TT.retrieve(pos);
@@ -1073,140 +1078,170 @@ namespace {
bool mateThreat = false; bool mateThreat = false;
// Null move search // Null move search
if(!pos.is_check() && allowNullmove && ok_to_do_nullmove(pos) if ( allowNullmove
&& approximateEval >= beta - NullMoveMargin) { && !pos.is_check()
UndoInfo u; && ok_to_do_nullmove(pos)
Value nullValue; && approximateEval >= beta - NullMoveMargin)
{
ss[ply].currentMove = MOVE_NULL;
ss[ply].currentMove = MOVE_NULL; UndoInfo u;
pos.do_null_move(u); pos.do_null_move(u);
nullValue = -search(pos, ss, -(beta-1), depth-4*OnePly, ply+1, false, Value nullValue = -search(pos, ss, -(beta-1), depth-4*OnePly, ply+1, false, threadID);
threadID); pos.undo_null_move(u);
pos.undo_null_move(u);
if(nullValue >= beta) { if (nullValue >= beta)
if(depth >= 6 * OnePly) { // Do zugzwang verification search {
Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); if (depth < 6 * OnePly)
if(v >= beta) return beta;
return beta;
// Do zugzwang verification search
Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
if (v >= beta)
return beta;
} else {
// The null move failed low, which means that we may be faced with
// some kind of threat. If the previous move was reduced, check if
// the move that refuted the null move was somehow connected to the
// 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;
ss[ply].threatMove = ss[ply + 1].currentMove;
if ( depth < ThreatDepth
&& ss[ply - 1].reduction
&& connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
return beta - 1;
} }
else
return beta;
}
else {
// The null move failed low, which means that we may be faced with
// some kind of threat. If the previous move was reduced, check if
// the move that refuted the null move was somehow connected to the
// 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;
ss[ply].threatMove = ss[ply+1].currentMove;
if(depth < ThreatDepth && ss[ply-1].reduction &&
connected_moves(pos, ss[ply-1].currentMove, ss[ply].threatMove))
return beta - 1;
}
} }
// Razoring: // Null move search not allowed, try razoring
else if(depth < RazorDepth && approximateEval < beta - RazorMargin && else if ( depth < RazorDepth
evaluate(pos, ei, threadID) < beta - RazorMargin) { && approximateEval < beta - RazorMargin
Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); && evaluate(pos, ei, threadID) < beta - RazorMargin)
if(v < beta) {
return v; Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
if (v < beta)
return v;
} }
// Internal iterative deepening // Go with internal iterative deepening if we don't have a TT move
if(UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly && if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly &&
evaluate(pos, ei, threadID) >= beta - IIDMargin) { evaluate(pos, ei, threadID) >= beta - IIDMargin)
search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); {
ttMove = ss[ply].pv[ply]; search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
ttMove = ss[ply].pv[ply];
} }
// Initialize a MovePicker object for the current position, and prepare // Initialize a MovePicker object for the current position, and prepare
// to search all moves: // to search all moves:
MovePicker mp = MovePicker(pos, false, ttMove, ss[ply].mateKiller, MovePicker mp = MovePicker(pos, false, ttMove, ss[ply].mateKiller,
ss[ply].killer1, ss[ply].killer2, depth); ss[ply].killer1, ss[ply].killer2, depth);
Move move, movesSearched[256]; Move move, movesSearched[256];
int moveCount = 0; int moveCount = 0;
Value value, bestValue = -VALUE_INFINITE, futilityValue = VALUE_NONE; Value value, bestValue = -VALUE_INFINITE;
Bitboard dcCandidates = mp.discovered_check_candidates(); Bitboard dcCandidates = mp.discovered_check_candidates();
Value futilityValue = VALUE_NONE;
bool isCheck = pos.is_check(); bool isCheck = pos.is_check();
bool useFutilityPruning = bool useFutilityPruning = UseFutilityPruning
UseFutilityPruning && depth < SelectiveDepth && !isCheck; && depth < SelectiveDepth
&& !isCheck;
// Loop through all legal moves until no moves remain or a beta cutoff // Loop through all legal moves until no moves remain or a beta cutoff
// occurs. // occurs.
while(bestValue < beta && !thread_should_stop(threadID) while( bestValue < beta
&& (move = mp.get_next_move()) != MOVE_NONE) { && (move = mp.get_next_move()) != MOVE_NONE
UndoInfo u; && !thread_should_stop(threadID))
Depth ext, newDepth; {
assert(move_is_ok(move));
bool singleReply = (isCheck && mp.number_of_moves() == 1); bool singleReply = (isCheck && mp.number_of_moves() == 1);
bool moveIsCheck = pos.move_is_check(move, dcCandidates); bool moveIsCheck = pos.move_is_check(move, dcCandidates);
bool moveIsCapture = pos.move_is_capture(move); bool moveIsCapture = pos.move_is_capture(move);
bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
assert(move_is_ok(move));
movesSearched[moveCount++] = ss[ply].currentMove = move; movesSearched[moveCount++] = ss[ply].currentMove = move;
// Decide the new search depth. // Decide the new search depth
ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat); Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat);
newDepth = depth - OnePly + ext; Depth newDepth = depth - OnePly + ext;
// Futility pruning // Futility pruning
if(useFutilityPruning && ext == Depth(0) && !moveIsCapture && if ( useFutilityPruning
!moveIsPassedPawnPush && !move_promotion(move)) { && ext == Depth(0)
&& !moveIsCapture
&& !moveIsPassedPawnPush
&& !move_promotion(move))
{
if ( moveCount >= 2 + int(depth)
&& ok_to_prune(pos, move, ss[ply].threatMove, depth))
continue;
if(moveCount >= 2 + int(depth) if (depth < 3 * OnePly && approximateEval < beta)
&& ok_to_prune(pos, move, ss[ply].threatMove, depth)) {
continue; if (futilityValue == VALUE_NONE)
futilityValue = evaluate(pos, ei, threadID) + (depth < 2 * OnePly ? FutilityMargin1 : FutilityMargin2);
if(depth < 3 * OnePly && approximateEval < beta) { if (futilityValue < beta)
if(futilityValue == VALUE_NONE) {
futilityValue = evaluate(pos, ei, threadID) if(futilityValue > bestValue)
+ ((depth < 2 * OnePly)? FutilityMargin1 : FutilityMargin2); bestValue = futilityValue;
if(futilityValue < beta) { continue;
if(futilityValue > bestValue) }
bestValue = futilityValue;
continue;
} }
}
} }
// Make and search the move. // Make and search the move
UndoInfo u;
pos.do_move(move, u, dcCandidates); pos.do_move(move, u, dcCandidates);
if(depth >= 2*OnePly && ext == Depth(0) && moveCount >= LMRNonPVMoves // Try to reduce non-pv search depth by one ply if move seems not problematic,
&& !moveIsCapture && !move_promotion(move) && !moveIsPassedPawnPush // if the move fails high will be re-searched at full depth.
&& !move_is_castle(move) if ( depth >= 2*OnePly
&& move != ss[ply].killer1 && move != ss[ply].killer2) { && ext == Depth(0)
ss[ply].reduction = OnePly; && moveCount >= LMRNonPVMoves
value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, && !moveIsCapture
threadID); && !move_promotion(move)
&& !moveIsPassedPawnPush
&& !move_is_castle(move)
&& move != ss[ply].killer1
&& move != ss[ply].killer2)
{
ss[ply].reduction = OnePly;
value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID);
} }
else else
value = beta; value = beta; // Just to trigger next condition
if(value >= beta) {
ss[ply].reduction = Depth(0); if (value >= beta) // Go with full depth non-pv search
value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); {
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
} }
pos.undo_move(move, u); pos.undo_move(move, u);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// New best move? // New best move?
if(value > bestValue) { if (value > bestValue)
{
bestValue = value; bestValue = value;
if(value >= beta) if (value >= beta)
update_pv(ss, ply); update_pv(ss, ply);
if(value == value_mate_in(ply + 1)) if (value == value_mate_in(ply + 1))
ss[ply].mateKiller = move; ss[ply].mateKiller = move;
} }
// Split? // Split?
if(ActiveThreads > 1 && bestValue < beta && depth >= MinimumSplitDepth if( ActiveThreads > 1
&& Iteration <= 99 && idle_thread_exists(threadID) && bestValue < beta
&& !AbortSearch && !thread_should_stop(threadID) && depth >= MinimumSplitDepth
&& Iteration <= 99
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
&& split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount, && split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount,
&mp, dcCandidates, threadID, false)) &mp, dcCandidates, threadID, false))
break; break;
@@ -1214,42 +1249,38 @@ namespace {
// All legal moves have been searched. A special case: If there were // All legal moves have been searched. A special case: If there were
// no legal moves, it must be mate or stalemate: // no legal moves, it must be mate or stalemate:
if(moveCount == 0) { if (moveCount == 0)
if(pos.is_check()) return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
return value_mated_in(ply);
else
return VALUE_DRAW;
}
// If the search is not aborted, update the transposition table, // If the search is not aborted, update the transposition table,
// history counters, and killer moves. This code is somewhat messy, // history counters, and killer moves. This code is somewhat messy,
// and definitely needs to be cleaned up. FIXME // and definitely needs to be cleaned up. FIXME
if(!AbortSearch && !thread_should_stop(threadID)) { if (AbortSearch || thread_should_stop(threadID))
if(bestValue < beta) return bestValue;
TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE,
VALUE_TYPE_UPPER); if (bestValue < beta)
else { TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER);
else
{
Move m = ss[ply].pv[ply]; Move m = ss[ply].pv[ply];
if (pos.square_is_empty(move_to(m)) && !move_promotion(m) && !move_is_ep(m))
{
for (int i = 0; i < moveCount - 1; i++)
if ( pos.square_is_empty(move_to(movesSearched[i]))
&& !move_promotion(movesSearched[i])
&& !move_is_ep(movesSearched[i]))
H.failure(pos.piece_on(move_from(movesSearched[i])), movesSearched[i]);
if(pos.square_is_empty(move_to(m)) && !move_promotion(m) && H.success(pos.piece_on(move_from(m)), m, depth);
!move_is_ep(m)) {
for(int i = 0; i < moveCount - 1; i++)
if(pos.square_is_empty(move_to(movesSearched[i]))
&& !move_promotion(movesSearched[i])
&& !move_is_ep(movesSearched[i]))
H.failure(pos.piece_on(move_from(movesSearched[i])),
movesSearched[i]);
H.success(pos.piece_on(move_from(m)), m, depth);
if(m != ss[ply].killer1) { if (m != ss[ply].killer1)
ss[ply].killer2 = ss[ply].killer1; {
ss[ply].killer1 = m; ss[ply].killer2 = ss[ply].killer1;
} ss[ply].killer1 = m;
}
} }
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER); TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
}
} }
return bestValue; return bestValue;
} }
@@ -1594,6 +1625,7 @@ namespace {
lock_release(&(sp->lock)); lock_release(&(sp->lock));
} }
// ok_to_use_TT() returns true if a transposition table score // ok_to_use_TT() returns true if a transposition table score
// can be used at a given point in search. // can be used at a given point in search.
@@ -1609,6 +1641,7 @@ namespace {
|| (is_upper_bound(tte->type()) && v < beta)); || (is_upper_bound(tte->type()) && v < beta));
} }
/// The RootMove class /// The RootMove class
// Constructor // Constructor