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Code Issues Releases Wiki Activity

Use SearchStack to pass allowNullmove

Browse source 
Also renamed allowNullmove in skipNullMove to reverse
the logic so that the field is initialized to 0 (false)
instead of 1 (true).

No functional change also with faked split.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-06-02 13:32:31 +01:00
parent 5804bef824
commit c51e12200a
2 changed files with 42 additions and 23 deletions
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64
src/search.cpp
View file

@ -285,7 +285,7 @@ namespace {
Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
template <NodeType PvNode> template <NodeType PvNode>
Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, bool allowNullmove, int threadID); Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID);
template <NodeType PvNode> template <NodeType PvNode>
Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID); Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID);
@ -876,7 +876,7 @@ namespace {
alpha = -VALUE_INFINITE; alpha = -VALUE_INFINITE;
// Full depth PV search, done on first move or after a fail high // Full depth PV search, done on first move or after a fail high
value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, 0); value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, 0);
} }
else else
{ {
@ -893,7 +893,7 @@ namespace {
if (ss->reduction) if (ss->reduction)
{ {
// Reduced depth non-pv search using alpha as upperbound // Reduced depth non-pv search using alpha as upperbound
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, 0); value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 0);
doFullDepthSearch = (value > alpha); doFullDepthSearch = (value > alpha);
} }
} }
@ -903,12 +903,12 @@ namespace {
{ {
// Full depth non-pv search using alpha as upperbound // Full depth non-pv search using alpha as upperbound
ss->reduction = Depth(0); ss->reduction = Depth(0);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, true, 0); value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, 0);
// If we are above alpha then research at same depth but as PV // If we are above alpha then research at same depth but as PV
// to get a correct score or eventually a fail high above beta. // to get a correct score or eventually a fail high above beta.
if (value > alpha) if (value > alpha)
value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, 0); value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, 0);
} }
} }
@ -1031,8 +1031,7 @@ namespace {
// search<>() is the main search function for both PV and non-PV nodes // search<>() is the main search function for both PV and non-PV nodes
template <NodeType PvNode> template <NodeType PvNode>
Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID) {
bool allowNullmove, int threadID) {
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE);
@ -1060,6 +1059,7 @@ namespace {
TM.incrementNodeCounter(threadID); TM.incrementNodeCounter(threadID);
ss->init(ply); ss->init(ply);
(ss + 1)->excludedMove = MOVE_NONE; (ss + 1)->excludedMove = MOVE_NONE;
(ss + 1)->skipNullMove = false;
(ss + 2)->initKillers(); (ss + 2)->initKillers();
if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls)
@ -1147,7 +1147,7 @@ namespace {
// We're betting that the opponent doesn't have a move that will reduce // We're betting that the opponent doesn't have a move that will reduce
// the score by more than futility_margin(depth) if we do a null move. // the score by more than futility_margin(depth) if we do a null move.
if ( !PvNode if ( !PvNode
&& allowNullmove && !ss->skipNullMove
&& depth < RazorDepth && depth < RazorDepth
&& refinedValue >= beta + futility_margin(depth, 0) && refinedValue >= beta + futility_margin(depth, 0)
&& !isCheck && !isCheck
@ -1160,7 +1160,7 @@ namespace {
// at least beta. Otherwise we do a null move if static value is not more than // at least beta. Otherwise we do a null move if static value is not more than
// NullMoveMargin under beta. // NullMoveMargin under beta.
if ( !PvNode if ( !PvNode
&& allowNullmove && !ss->skipNullMove
&& depth > OnePly && depth > OnePly
&& refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0) && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0)
&& !isCheck && !isCheck
@ -1178,8 +1178,13 @@ namespace {
pos.do_null_move(st); pos.do_null_move(st);
(ss+1)->skipNullMove = true;
nullValue = depth-R*OnePly < OnePly ? -qsearch<NonPV>(pos, ss+1, -beta, -alpha, Depth(0), threadID) nullValue = depth-R*OnePly < OnePly ? -qsearch<NonPV>(pos, ss+1, -beta, -alpha, Depth(0), threadID)
: - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*OnePly, false, threadID); : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*OnePly, threadID);
(ss+1)->skipNullMove = false;
pos.undo_null_move(); pos.undo_null_move();
if (nullValue >= beta) if (nullValue >= beta)
@ -1189,8 +1194,14 @@ namespace {
nullValue = beta; nullValue = beta;
// Do zugzwang verification search at high depths // Do zugzwang verification search at high depths
if ( depth < 6 * OnePly if (depth < 6 * OnePly)
|| search<NonPV>(pos, ss, alpha, beta, depth-5*OnePly, false, threadID) >= beta) return nullValue;
ss->skipNullMove = true;
Value v = search<NonPV>(pos, ss, alpha, beta, depth-5*OnePly, threadID);
ss->skipNullMove = false;
if (v >= beta)
return nullValue; return nullValue;
} }
else else
@ -1218,7 +1229,11 @@ namespace {
&& (PvNode || (!isCheck && ss->eval >= beta - IIDMargin))) && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin)))
{ {
Depth d = (PvNode ? depth - 2 * OnePly : depth / 2); Depth d = (PvNode ? depth - 2 * OnePly : depth / 2);
search<PvNode>(pos, ss, alpha, beta, d, false, threadID);
ss->skipNullMove = true;
search<PvNode>(pos, ss, alpha, beta, d, threadID);
ss->skipNullMove = false;
ttMove = ss->pv[ply]; ttMove = ss->pv[ply];
tte = TT.retrieve(posKey); tte = TT.retrieve(posKey);
} }
@ -1267,7 +1282,9 @@ namespace {
{ {
Value b = ttValue - SingularExtensionMargin; Value b = ttValue - SingularExtensionMargin;
ss->excludedMove = move; ss->excludedMove = move;
Value v = search<NonPV>(pos, ss, b - 1, b, depth / 2, false, threadID); ss->skipNullMove = true;
Value v = search<NonPV>(pos, ss, b - 1, b, depth / 2, threadID);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE; ss->excludedMove = MOVE_NONE;
if (v < ttValue - SingularExtensionMargin) if (v < ttValue - SingularExtensionMargin)
@ -1316,7 +1333,7 @@ namespace {
// The first move in list is the expected PV // The first move in list is the expected PV
if (PvNode && moveCount == 1) if (PvNode && moveCount == 1)
value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0), threadID) value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0), threadID)
: - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, threadID); : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, threadID);
else else
{ {
// Step 14. Reduced depth search // Step 14. Reduced depth search
@ -1334,7 +1351,7 @@ namespace {
{ {
Depth d = newDepth - ss->reduction; Depth d = newDepth - ss->reduction;
value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID)
: - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true, threadID); : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, threadID);
doFullDepthSearch = (value > alpha); doFullDepthSearch = (value > alpha);
} }
@ -1347,7 +1364,7 @@ namespace {
assert(newDepth - OnePly >= OnePly); assert(newDepth - OnePly >= OnePly);
ss->reduction = OnePly; ss->reduction = OnePly;
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, threadID); value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, threadID);
doFullDepthSearch = (value > alpha); doFullDepthSearch = (value > alpha);
} }
ss->reduction = Depth(0); // Restore original reduction ss->reduction = Depth(0); // Restore original reduction
@ -1357,14 +1374,14 @@ namespace {
if (doFullDepthSearch) if (doFullDepthSearch)
{ {
value = newDepth < OnePly ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) value = newDepth < OnePly ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID)
: - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, true, threadID); : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, threadID);
// Step extra. pv search (only in PV nodes) // Step extra. pv search (only in PV nodes)
// Search only for possible new PV nodes, if instead value >= beta then // Search only for possible new PV nodes, if instead value >= beta then
// parent node fails low with value <= alpha and tries another move. // parent node fails low with value <= alpha and tries another move.
if (PvNode && value > alpha && value < beta) if (PvNode && value > alpha && value < beta)
value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0), threadID) value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0), threadID)
: - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, threadID); : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, threadID);
} }
} }
@ -1725,7 +1742,7 @@ namespace {
Value localAlpha = sp->alpha; Value localAlpha = sp->alpha;
Depth d = newDepth - ss->reduction; Depth d = newDepth - ss->reduction;
value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID) value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID)
: - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, d, true, threadID); : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, d, threadID);
doFullDepthSearch = (value > localAlpha); doFullDepthSearch = (value > localAlpha);
} }
@ -1738,7 +1755,7 @@ namespace {
ss->reduction = OnePly; ss->reduction = OnePly;
Value localAlpha = sp->alpha; Value localAlpha = sp->alpha;
value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID); value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, threadID);
doFullDepthSearch = (value > localAlpha); doFullDepthSearch = (value > localAlpha);
} }
ss->reduction = Depth(0); // Restore original reduction ss->reduction = Depth(0); // Restore original reduction
@ -1749,14 +1766,14 @@ namespace {
{ {
Value localAlpha = sp->alpha; Value localAlpha = sp->alpha;
value = newDepth < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID) value = newDepth < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID)
: - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, true, threadID); : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, threadID);
// Step extra. pv search (only in PV nodes) // Step extra. pv search (only in PV nodes)
// Search only for possible new PV nodes, if instead value >= beta then // Search only for possible new PV nodes, if instead value >= beta then
// parent node fails low with value <= alpha and tries another move. // parent node fails low with value <= alpha and tries another move.
if (PvNode && value > localAlpha && value < sp->beta) if (PvNode && value > localAlpha && value < sp->beta)
value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -sp->beta, -sp->alpha, Depth(0), threadID) value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -sp->beta, -sp->alpha, Depth(0), threadID)
: - search<PV>(pos, ss+1, -sp->beta, -sp->alpha, newDepth, false, threadID); : - search<PV>(pos, ss+1, -sp->beta, -sp->alpha, newDepth, threadID);
} }
// Step 16. Undo move // Step 16. Undo move
@ -2227,6 +2244,7 @@ namespace {
ss->init(i); ss->init(i);
ss->initKillers(); ss->initKillers();
ss->excludedMove = MOVE_NONE; ss->excludedMove = MOVE_NONE;
ss->skipNullMove = false;
} }
} }

1
src/search.h
View file

@ -58,6 +58,7 @@ struct SearchStack {
Move killers[KILLER_MAX]; Move killers[KILLER_MAX];
Depth reduction; Depth reduction;
Value eval; Value eval;
bool skipNullMove;
void init(int ply); void init(int ply);
void initKillers(); void initKillers();