In multi-threads runs with debug on we experience some
asserts due to the fact that TT access is intrinsecally
racy and its contents cannot be always trusted so must
be validated before to be used and this is what the
patch does.
No functional case.
// smooth experience in analysis mode. We don't probe at Root nodes otherwise
// we should also update RootMoveList to avoid bogus output.
if ( !RootNode
// 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
+ && 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)))
{
&& ( PvNode ? tte->type() == BOUND_EXACT
: ttValue >= beta ? (tte->type() & BOUND_LOWER)
: (tte->type() & BOUND_UPPER)))
{
- assert(ttValue != VALUE_NONE); // Due to depth > DEPTH_NONE
-
TT.refresh(tte);
ss->currentMove = ttMove; // Can be MOVE_NONE
TT.refresh(tte);
ss->currentMove = ttMove; // Can be MOVE_NONE
- assert(tte->static_value() != VALUE_NONE);
- assert(ttValue != VALUE_NONE || tte->type() == BOUND_NONE);
+ // Following asserts are valid only in single thread condition because
+ // TT access is always racy and its contents cannot be trusted.
+ assert(tte->static_value() != VALUE_NONE || Threads.size() > 1);
+ assert(ttValue != VALUE_NONE || tte->type() == BOUND_NONE || Threads.size() > 1);
ss->staticEval = eval = tte->static_value();
ss->evalMargin = tte->static_value_margin();
ss->staticEval = eval = tte->static_value();
ss->evalMargin = tte->static_value_margin();
+ if (eval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race
+ eval = ss->staticEval = evaluate(pos, ss->evalMargin);
+
// Can ttValue be used as a better position evaluation?
// Can ttValue be used as a better position evaluation?
- if ( ((tte->type() & BOUND_LOWER) && ttValue > eval)
- || ((tte->type() & BOUND_UPPER) && ttValue < eval))
- eval = ttValue;
+ if (ttValue != VALUE_NONE)
+ if ( ((tte->type() & BOUND_LOWER) && ttValue > eval)
+ || ((tte->type() & BOUND_UPPER) && ttValue < eval))
+ eval = ttValue;
// 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;
// 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
+ 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)))
{
&& ( PvNode ? tte->type() == BOUND_EXACT
: ttValue >= beta ? (tte->type() & BOUND_LOWER)
: (tte->type() & BOUND_UPPER)))
{
- assert(ttValue != VALUE_NONE); // Due to ttDepth > DEPTH_NONE
-
ss->currentMove = ttMove; // Can be MOVE_NONE
return ttValue;
}
ss->currentMove = ttMove; // Can be MOVE_NONE
return ttValue;
}
- assert(tte->static_value() != VALUE_NONE);
+ assert(tte->static_value() != VALUE_NONE || Threads.size() > 1);
ss->staticEval = bestValue = tte->static_value();
ss->evalMargin = tte->static_value_margin();
ss->staticEval = bestValue = tte->static_value();
ss->evalMargin = tte->static_value_margin();
+
+ if (ss->staticEval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race
+ ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
}
else
ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
}
else
ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);