// Step 8. Futility pruning: child node (~50 Elo)
if ( !PvNode
- && depth < 6
+ && depth < 8
&& eval - futility_margin(depth, improving) >= beta
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins
return eval;
thisThread->rootMoves.begin() + thisThread->pvLast, move))
continue;
+ // Check for legality
+ if (!rootNode && !pos.legal(move))
+ continue;
+
ss->moveCount = ++moveCount;
if (rootNode && thisThread == Threads.main() && Time.elapsed() > 3000)
// Castling extension
if (type_of(move) == CASTLING)
extension = 1;
+
+ // Late irreversible move extension
+ if ( move == ttMove
+ && pos.rule50_count() > 80
+ && (captureOrPromotion || type_of(movedPiece) == PAWN))
+ extension = 2;
// Add extension to new depth
newDepth += extension;
// Speculative prefetch as early as possible
prefetch(TT.first_entry(pos.key_after(move)));
- // Check for legality just before making the move
- if (!rootNode && !pos.legal(move))
- {
- ss->moveCount = --moveCount;
- continue;
- }
-
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]