assert(0 <= ss->ply && ss->ply < MAX_PLY);
ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
- (ss+1)->skipEarlyPruning = false; (ss+1)->reduction = DEPTH_ZERO;
+ (ss+1)->skipEarlyPruning = false;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
// Step 4. Transposition table lookup. We don't want the score of a partial
// re-searched at full depth.
if ( depth >= 3 * ONE_PLY
&& moveCount > 1
- && !captureOrPromotion
- && move != ss->killers[0]
- && move != ss->killers[1])
+ && !captureOrPromotion)
{
- ss->reduction = reduction<PvNode>(improving, depth, moveCount);
+ Depth r = reduction<PvNode>(improving, depth, moveCount);
// Increase reduction for cut nodes and moves with a bad history
if ( (!PvNode && cutNode)
|| ( thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO
&& cmh[pos.piece_on(to_sq(move))][to_sq(move)] <= VALUE_ZERO))
- ss->reduction += ONE_PLY;
+ r += ONE_PLY;
// Decrease reduction for moves with a good history
if ( thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)] > VALUE_ZERO
&& cmh[pos.piece_on(to_sq(move))][to_sq(move)] > VALUE_ZERO)
- ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
+ r = std::max(DEPTH_ZERO, r - ONE_PLY);
// Decrease reduction for moves that escape a capture
- if ( ss->reduction
+ if ( r
&& type_of(move) == NORMAL
&& type_of(pos.piece_on(to_sq(move))) != PAWN
&& pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO)
- ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
+ r = std::max(DEPTH_ZERO, r - ONE_PLY);
- Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
+ Depth d = std::max(newDepth - r, ONE_PLY);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
- doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
- ss->reduction = DEPTH_ZERO;
+ doFullDepthSearch = (value > alpha && r != DEPTH_ZERO);
}
else
doFullDepthSearch = !PvNode || moveCount > 1;