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Avoid searching TT twice for the same key/position during probe() and store().

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Just keep the pointer and remove code from tt.cpp

STC
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 13620 W: 2810 L: 2665 D: 8145

LTC
LLR: 2.97 (-2.94,2.94) [0.00,6.00]
Total: 13021 W: 2238 L: 2073 D: 8710STC http://tests.stockfishchess.org/tests/view/548436860ebc59331739b90c

STC 4MB
ELO: 2.41 +-2.2 (95%) LOS: 98.6%
Total: 40000 W: 8175 L: 7897 D: 23928

LTC 16MB
ELO: 1.78 +-2.0 (95%) LOS: 96.1%
Total: 39683 W: 6763 L: 6560 D: 26360

Resolves #151

Bench: 8116521
This commit is contained in:
mstembera
2014-12-13 07:16:35 +00:00
committed by Joona Kiiski
parent 7b4828b68c
commit 14cf27e6f6
3 changed files with 67 additions and 81 deletions
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48
src/tt.cpp
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@@ -54,7 +54,7 @@ void TranspositionTable::resize(size_t mbSize) {
/// TranspositionTable::clear() overwrites the entire transposition table
/// with zeroes. It is called whenever the table is resized, or when the
/// with zeros. It is called whenever the table is resized, or when the
/// user asks the program to clear the table (from the UCI interface).
void TranspositionTable::clear() {
@@ -64,47 +64,28 @@ void TranspositionTable::clear() {
/// TranspositionTable::probe() looks up the current position in the
/// transposition table. Returns a pointer to the TTEntry or NULL if
/// position is not found.
const TTEntry* TranspositionTable::probe(const Key key) const {
TTEntry* const tte = first_entry(key);
const uint16_t key16 = key >> 48;
for (unsigned i = 0; i < TTClusterSize; ++i)
if (tte[i].key16 == key16)
{
tte[i].genBound8 = uint8_t(generation | tte[i].bound()); // Refresh
return &tte[i];
}
return NULL;
}
/// TranspositionTable::store() writes a new entry containing position key and
/// valuable information of current position. The lowest order bits of position
/// key are used to decide in which cluster the position will be placed.
/// When a new entry is written and there are no empty entries available in the
/// cluster, it replaces the least valuable of the entries. A TTEntry t1 is considered
/// transposition table. It returns true and a pointer to the TTEntry if
/// the position is found. Otherwise, it returns false and a pointer to an empty or
/// least valuable TTEntry to be replaced later. A TTEntry t1 is considered
/// to be 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 key, Value v, Bound b, Depth d, Move m, Value statV) {
TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
TTEntry* const tte = first_entry(key);
const uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
const uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
for (unsigned i = 0; i < TTClusterSize; ++i)
if (!tte[i].key16 || tte[i].key16 == key16) // Empty or overwrite old
if (!tte[i].key16 || tte[i].key16 == key16)
{
// Save preserving any existing ttMove
tte[i].save(key16, v, b, d, m ? m : tte[i].move(), generation, statV);
return;
if (tte[i].key16)
tte[i].genBound8 = uint8_t(generation | tte[i].bound()); // Refresh
found = (bool)tte[i].key16;
return &tte[i];
}
// Implement replace strategy
// Find an entry to be replaced according to the replacement strategy
TTEntry* replace = tte;
for (unsigned i = 1; i < TTClusterSize; ++i)
if ( (( tte[i].genBound8 & 0xFC) == generation || tte[i].bound() == BOUND_EXACT)
@@ -112,5 +93,6 @@ void TranspositionTable::store(const Key key, Value v, Bound b, Depth d, Move m,
- (tte[i].depth8 < replace->depth8) < 0)
replace = &tte[i];
replace->save(key16, v, b, d, m, generation, statV);
found = false;
return replace;
}