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Futility pruning simplification

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1/ eval margin and gains removed:
16bit are now free on TT entries, due to the removal of eval margin. may be useful
in the future :) gains removed: use instead by Value(128). search() and qsearch()
are now consistent in this regard.

2/ futility_margin()
linear formula instead of complex (log(depth), movecount) formula.

3/ unify pre & post futility pruning
pre futility pruning used depth < 7 plies, while post futility pruning used
depth < 4 plies. Now it's always depth < 7.

Tested with fixed number of games both at short TC:
ELO: 0.82 +-2.1 (95%) LOS: 77.3%
Total: 40000 W: 7939 L: 7845 D: 24216

And long TC
ELO: 0.59 +-2.0 (95%) LOS: 71.9%
Total: 40000 W: 6876 L: 6808 D: 26316

bench 7243575
This commit is contained in:
Lucas Braesch
2013-11-08 18:42:22 +08:00
committed by Marco Costalba
parent 343544f3f7
commit eed508b444
7 changed files with 59 additions and 116 deletions
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8
src/tt.h
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@@ -36,7 +36,7 @@
struct TTEntry {
void save(uint32_t k, Value v, Bound b, Depth d, Move m, int g, Value ev, Value em) {
void save(uint32_t k, Value v, Bound b, Depth d, Move m, int g, Value ev) {
key32 = (uint32_t)k;
move16 = (uint16_t)m;
@@ -45,7 +45,6 @@ struct TTEntry {
value16 = (int16_t)v;
depth16 = (int16_t)d;
evalValue = (int16_t)ev;
evalMargin = (int16_t)em;
}
void set_generation(uint8_t g) { generation8 = g; }
@@ -56,13 +55,12 @@ struct TTEntry {
Bound bound() const { return (Bound)bound8; }
int generation() const { return (int)generation8; }
Value eval_value() const { return (Value)evalValue; }
Value eval_margin() const { return (Value)evalMargin; }
private:
uint32_t key32;
uint16_t move16;
uint8_t bound8, generation8;
int16_t value16, depth16, evalValue, evalMargin;
int16_t value16, depth16, evalValue;
};
@@ -85,7 +83,7 @@ public:
void refresh(const TTEntry* tte) const;
void set_size(size_t mbSize);
void clear();
void store(const Key key, Value v, Bound type, Depth d, Move m, Value statV, Value kingD);
void store(const Key key, Value v, Bound type, Depth d, Move m, Value statV);
private:
uint32_t hashMask;