Key posKey;
Move ttMove, move, excludedMove, bestMove, threatMove;
Depth ext, newDepth;
- Value bestValue, value, ttValue;
+ Value bestValue, value, ttValue, ttValueUpper;
Value eval, nullValue, futilityValue;
bool inCheck, givesCheck, pvMove, singularExtensionNode;
bool captureOrPromotion, dangerous, doFullDepthSearch;
tte = TT.probe(posKey);
ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
+ ttValueUpper = tte ? value_from_tt(tte->value_upper(), ss->ply) : VALUE_NONE;
// At PV nodes we check for exact scores, while at non-PV nodes we check for
// a fail high/low. Biggest advantage at probing at PV nodes is to have a
// smooth experience in analysis mode. We don't probe at Root nodes otherwise
// we should also update RootMoveList to avoid bogus output.
- if ( !RootNode
- && tte
- && tte->depth() >= depth
- && ttValue != VALUE_NONE // Only in case of TT access race
- && ( PvNode ? tte->type() == BOUND_EXACT
- : ttValue >= beta ? (tte->type() & BOUND_LOWER)
- : (tte->type() & BOUND_UPPER)))
+ if (!RootNode && tte)
{
- TT.refresh(tte);
- ss->currentMove = ttMove; // Can be MOVE_NONE
+ // Fail High
+ if ( (tte->type() & BOUND_LOWER)
+ && ttValue >= beta
+ && tte->depth() >= depth
+ && ttValue != VALUE_NONE) // Only in case of TT access race
+ {
+ // Update killers, we assume ttMove caused a cut-off
+ if ( ttMove
+ && !pos.is_capture_or_promotion(ttMove)
+ && ttMove != ss->killers[0])
+ {
+ ss->killers[1] = ss->killers[0];
+ ss->killers[0] = ttMove;
+ }
+ TT.refresh(tte);
+ ss->currentMove = ttMove; // Can be MOVE_NONE
+ return ttValue;
+ }
- if ( ttValue >= beta
- && ttMove
- && !pos.is_capture_or_promotion(ttMove)
- && ttMove != ss->killers[0])
+ // Fail Low
+ if ( (tte->type() & BOUND_UPPER)
+ && ttValueUpper <= alpha
+ && tte->depth_upper() >= depth
+ && ttValueUpper != VALUE_NONE) // Only in case of TT access race
{
- ss->killers[1] = ss->killers[0];
- ss->killers[0] = ttMove;
+ TT.refresh(tte);
+ ss->currentMove = ttMove; // Can be MOVE_NONE
+ return ttValueUpper;
}
- return ttValue;
}
// Step 5. Evaluate the position statically and update parent's gain statistics
const TTEntry* tte;
Key posKey;
Move ttMove, move, bestMove;
- Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
+ Value bestValue, value, ttValue, ttValueUpper, futilityValue, futilityBase, oldAlpha;
bool givesCheck, enoughMaterial, evasionPrunable, fromNull;
Depth ttDepth;
tte = TT.probe(posKey);
ttMove = tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;
+ ttValueUpper = tte ? value_from_tt(tte->value_upper(),ss->ply) : VALUE_NONE;
// Decide whether or not to include checks, this fixes also the type of
// TT entry depth that we are going to use. Note that in qsearch we use
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
: DEPTH_QS_NO_CHECKS;
- if ( tte
- && tte->depth() >= ttDepth
- && ttValue != VALUE_NONE // Only in case of TT access race
- && ( PvNode ? tte->type() == BOUND_EXACT
- : ttValue >= beta ? (tte->type() & BOUND_LOWER)
- : (tte->type() & BOUND_UPPER)))
+ if (tte)
{
- ss->currentMove = ttMove; // Can be MOVE_NONE
- return ttValue;
+ // Fail High
+ if ( (tte->type() & BOUND_LOWER)
+ && ttValue >= beta
+ && tte->depth() >= ttDepth
+ && ttValue != VALUE_NONE) // Only in case of TT access race
+ {
+ ss->currentMove = ttMove; // Can be MOVE_NONE
+ return ttValue;
+ }
+
+ // Fail Low
+ if ( (tte->type() & BOUND_UPPER)
+ && ttValueUpper <= alpha
+ && tte->depth_upper() >= ttDepth
+ && ttValueUpper != VALUE_NONE) // Only in case of TT access race
+ {
+ ss->currentMove = ttMove; // Can be MOVE_NONE
+ return ttValueUpper;
+ }
}
// Evaluate the position statically