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Flag critical search tree in hash table

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Introducing new concept, saving principal lines into the transposition table
to generate a "critical search tree" which we can reuse later for intelligent
pruning/extension decisions.

For instance in this patch we just reduce reduction for these lines. But a lot
of other ideas are possible.

To go further : tune some parameters, how to add or remove lines from the
critical search tree, how to use these lines in search choices, etc.

STC :
LLR: 2.94 (-2.94,2.94) [0.50,4.50]
Total: 59761 W: 13321 L: 12863 D: 33577 +2.23 ELO
http://tests.stockfishchess.org/tests/view/5c34da5d0ebc596a450c53d3

LTC :
LLR: 2.96 (-2.94,2.94) [0.00,3.50]
Total: 26826 W: 4439 L: 4191 D: 18196 +2.9 ELO
http://tests.stockfishchess.org/tests/view/5c35ceb00ebc596a450c65b2

Special thanks to Miguel Lahoz for his help in transposition table in/out.

Bench: 3399866
This commit is contained in:
MJZ1977
2019-01-09 15:05:28 +01:00
committed by Stéphane Nicolet
parent f69106f7bb
commit 70880b8e24
4 changed files with 31 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
src/tt.cpp
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@@ -31,7 +31,7 @@
TranspositionTable TT; // Our global transposition table
/// TTEntry::save saves a TTEntry
void TTEntry::save(Key k, Value v, Bound b, Depth d, Move m, Value ev) {
void TTEntry::save(Key k, Value v, bool PvNode, Bound b, Depth d, Move m, Value ev) {
assert(d / ONE_PLY * ONE_PLY == d);
@@ -47,7 +47,7 @@ void TTEntry::save(Key k, Value v, Bound b, Depth d, Move m, Value ev) {
key16 = (uint16_t)(k >> 48);
value16 = (int16_t)v;
eval16 = (int16_t)ev;
genBound8 = (uint8_t)(TT.generation8 | b);
genBound8 = (uint8_t)(TT.generation8 | PvNode << 2 | b);
depth8 = (int8_t)(d / ONE_PLY);
}
}
@@ -122,7 +122,7 @@ TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
for (int i = 0; i < ClusterSize; ++i)
if (!tte[i].key16 || tte[i].key16 == key16)
{
tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
tte[i].genBound8 = uint8_t(generation8 | tte[i].pv_hit() << 2 | tte[i].bound()); // Refresh
return found = (bool)tte[i].key16, &tte[i];
}
@@ -131,11 +131,11 @@ TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
TTEntry* replace = tte;
for (int i = 1; i < ClusterSize; ++i)
// Due to our packed storage format for generation and its cyclic
// nature we add 259 (256 is the modulus plus 3 to keep the lowest
// nature we add 263 (263 is the modulus plus 7 to keep the lowest
// two bound bits from affecting the result) to calculate the entry
// age correctly even after generation8 overflows into the next cycle.
if ( replace->depth8 - ((259 + generation8 - replace->genBound8) & 0xFC) * 2
> tte[i].depth8 - ((259 + generation8 - tte[i].genBound8) & 0xFC) * 2)
if ( replace->depth8 - ((263 + generation8 - replace->genBound8) & 0xF8)
> tte[i].depth8 - ((263 + generation8 - tte[i].genBound8) & 0xF8))
replace = &tte[i];
return found = false, replace;