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Store distinct upper and lower bound scores

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This is more complex than what I'd like but I
was unable to split in small chunks.

Here we add 2 slots to TTEntry (valueUpper and depthUpper)
so that sizeof(TTEntry) returns to the original 16 bytes
and we can pack exactly 4 entries in a 64 bytes cache line.

Now we save an upper bound score alongside a lower (exact)
score. The idea is to increase TT cut-offs rates becuase
there is now an higher probability for a node to use TT info.

This patch is highly experimental and probably needs further
steps as is hinted by an unrealistic bench number:

bench: 2022385
This commit is contained in:
Marco Costalba
2012-12-09 11:08:37 +01:00
parent 23bdd06442
commit feeafb0a50
4 changed files with 94 additions and 42 deletions
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11
src/tt.cpp
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@@ -82,7 +82,7 @@ void TranspositionTable::clear() {
/// more valuable than a TTEntry t2 if t1 is from the current search and t2 is from
/// a previous search, or if the depth of t1 is bigger than the depth of t2.
void TranspositionTable::store(const Key posKey, Value v, Bound t, Depth d, Move m) {
void TranspositionTable::store(const Key posKey, Value v, Bound b, Depth d, Move m) {
int c1, c2, c3;
TTEntry *tte, *replace;
@@ -92,13 +92,16 @@ void TranspositionTable::store(const Key posKey, Value v, Bound t, Depth d, Move
for (int i = 0; i < ClusterSize; i++, tte++)
{
if (!tte->key() || tte->key() == posKey32) // Empty or overwrite old
if (!tte->key())
tte->save(posKey32, v, b, d, m, generation);
if (tte->key() == posKey32)
{
// Preserve any existing ttMove
if (m == MOVE_NONE)
m = tte->move();
tte->save(posKey32, v, t, d, m, generation);
tte->update(v, b, d, m, generation);
return;
}
@@ -110,7 +113,7 @@ void TranspositionTable::store(const Key posKey, Value v, Bound t, Depth d, Move
if (c1 + c2 + c3 > 0)
replace = tte;
}
replace->save(posKey32, v, t, d, m, generation);
replace->save(posKey32, v, b, d, m, generation);
}