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Restore old BOUND_EXACT logic in qsearch

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In case a PvNode node has a static evaluation above alpha but
no available moves we want to flag the node as BOUND_EXACT,
not as BOUND_UPPER as is currently.

The behaviour was recently introduced with patch d471c49700
of 3/10/2012

Spotted by Hongzhi Cheng.

bench: 5558464
This commit is contained in:
Marco Costalba
2012-11-11 11:49:02 +01:00
parent c45a4e0b48
commit 116234d6c6
1 changed files with 6 additions and 2 deletions
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8
src/search.cpp
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@@ -1101,10 +1101,14 @@ split_point_start: // At split points actual search starts from here
const TTEntry* tte;
Key posKey;
Move ttMove, move, bestMove;
Value bestValue, value, ttValue, futilityValue, futilityBase;
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
bool givesCheck, enoughMaterial, evasionPrunable, fromNull;
Depth ttDepth;
// To flag BOUND_EXACT a node with eval above alpha and no available moves
if (PvNode)
oldAlpha = alpha;
ss->currentMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
fromNull = (ss-1)->currentMove == MOVE_NULL;
@@ -1291,7 +1295,7 @@ split_point_start: // At split points actual search starts from here
return mated_in(ss->ply); // Plies to mate from the root
TT.store(posKey, value_to_tt(bestValue, ss->ply),
PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER,
PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER,
ttDepth, bestMove, ss->staticEval, ss->evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);