From f3809f2a18bd3a348ba80e1e07d014834603499b Mon Sep 17 00:00:00 2001 From: Joona Kiiski Date: Sun, 11 Apr 2010 20:21:26 +0300 Subject: [PATCH] Introduce NullStatus enum No functional change Signed-off-by: Marco Costalba --- src/search.cpp | 47 +++++++++++++++++++++++++++-------------------- 1 file changed, 27 insertions(+), 20 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index dfe5efa9..aaff2f54 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -104,6 +104,13 @@ namespace { }; + // FIXME: document me + + enum NullStatus { + ALLOW_NULLMOVE, + FORBID_NULLMOVE, + VERIFY_NULLMOVE + }; // RootMove struct is used for moves at the root at the tree. For each // root move, we store a score, a node count, and a PV (really a refutation @@ -281,7 +288,7 @@ namespace { Value id_loop(const Position& pos, Move searchMoves[]); Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr); Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); - Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE); + Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, NullStatus nullStatus, int threadID, Move excludedMove = MOVE_NONE); Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); void sp_search(SplitPoint* sp, int threadID); void sp_search_pv(SplitPoint* sp, int threadID); @@ -886,7 +893,7 @@ namespace { if (ss[0].reduction) { // Reduced depth non-pv search using alpha as upperbound - value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0); + value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, ALLOW_NULLMOVE, 0); doFullDepthSearch = (value > alpha); } } @@ -896,7 +903,7 @@ namespace { { // Full depth non-pv search using alpha as upperbound ss[0].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, 1, true, 0); + value = -search(pos, ss, -alpha, newDepth, 1, ALLOW_NULLMOVE, 0); // 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. @@ -1131,7 +1138,7 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); + Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, FORBID_NULLMOVE, threadID, move); if (excValue < ttValue - SingularExtensionMargin) ext = OnePly; @@ -1167,7 +1174,7 @@ namespace { ss[ply].reduction = pv_reduction(depth, moveCount); if (ss[ply].reduction) { - value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID); + value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, ALLOW_NULLMOVE, threadID); doFullDepthSearch = (value > alpha); } } @@ -1176,7 +1183,7 @@ namespace { if (doFullDepthSearch) { ss[ply].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); + value = -search(pos, ss, -alpha, newDepth, ply+1, ALLOW_NULLMOVE, threadID); // Step extra. pv search (only in PV nodes) if (value > alpha && value < beta) @@ -1251,7 +1258,7 @@ namespace { // search() is the search function for zero-width nodes. Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, - int ply, bool allowNullmove, int threadID, Move excludedMove) { + int ply, NullStatus nullStatus, int threadID, Move excludedMove) { assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(ply >= 0 && ply < PLY_MAX); @@ -1299,7 +1306,7 @@ namespace { tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); - if (tte && ok_to_use_TT(tte, depth, beta, ply, allowNullmove)) + if (tte && ok_to_use_TT(tte, depth, beta, ply, nullStatus == ALLOW_NULLMOVE)) { ss[ply].currentMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); @@ -1339,7 +1346,7 @@ namespace { // Step 7. Static null move pruning // 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. - if ( allowNullmove + if ( nullStatus == ALLOW_NULLMOVE && depth < RazorDepth && !isCheck && !value_is_mate(beta) @@ -1351,7 +1358,7 @@ namespace { // When we jump directly to qsearch() we do a null move only if static value is // at least beta. Otherwise we do a null move if static value is not more than // NullMoveMargin under beta. - if ( allowNullmove + if ( nullStatus == ALLOW_NULLMOVE && depth > OnePly && !isCheck && !value_is_mate(beta) @@ -1369,7 +1376,7 @@ namespace { pos.do_null_move(st); - nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); + nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, FORBID_NULLMOVE, threadID); pos.undo_null_move(); @@ -1382,7 +1389,7 @@ namespace { // Do zugzwang verification search for high depths, don't store in TT // if search was stopped. if ( ( depth < 6 * OnePly - || search(pos, ss, beta, depth-5*OnePly, ply, false, threadID) >= beta) + || search(pos, ss, beta, depth-5*OnePly, ply, FORBID_NULLMOVE, threadID) >= beta) && !AbortSearch && !TM.thread_should_stop(threadID)) { @@ -1415,7 +1422,7 @@ namespace { && !isCheck && ss[ply].eval >= beta - IIDMargin) { - search(pos, ss, beta, depth/2, ply, false, threadID); + search(pos, ss, beta, depth/2, ply, FORBID_NULLMOVE, threadID); ttMove = ss[ply].pv[ply]; tte = TT.retrieve(posKey); } @@ -1457,7 +1464,7 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); + Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, FORBID_NULLMOVE, threadID, move); if (excValue < ttValue - SingularExtensionMargin) ext = OnePly; @@ -1511,7 +1518,7 @@ namespace { ss[ply].reduction = nonpv_reduction(depth, moveCount); if (ss[ply].reduction) { - value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID); + value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, ALLOW_NULLMOVE, threadID); doFullDepthSearch = (value >= beta); } } @@ -1520,7 +1527,7 @@ namespace { if (doFullDepthSearch) { ss[ply].reduction = Depth(0); - value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); + value = -search(pos, ss, -(beta-1), newDepth, ply+1, ALLOW_NULLMOVE, threadID); } // Step 16. Undo move @@ -1870,7 +1877,7 @@ namespace { ss[sp->ply].reduction = nonpv_reduction(sp->depth, moveCount); if (ss[sp->ply].reduction) { - value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); + value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, ALLOW_NULLMOVE, threadID); doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID)); } } @@ -1879,7 +1886,7 @@ namespace { if (doFullDepthSearch) { ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); + value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, ALLOW_NULLMOVE, threadID); } // Step 16. Undo move @@ -1976,7 +1983,7 @@ namespace { if (ss[sp->ply].reduction) { Value localAlpha = sp->alpha; - value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); + value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, ALLOW_NULLMOVE, threadID); doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID)); } } @@ -1986,7 +1993,7 @@ namespace { { Value localAlpha = sp->alpha; ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID); + value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, ALLOW_NULLMOVE, threadID); if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID)) { -- 2.39.2