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Similarize pruning code in search() and sp_search()

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Use futility pruning also in split points.
Do not use history pruning in split points when
getting mated.

After 1000 games on Joona QUAD
Orig - Mod: 496 - 504

Added an optimization to avoid a costly lock in the
very common case that sp->futilityValue <= sp->bestValue.
A test on a dual CPU shows only 114 hits on 23196 events,
so avoid a lock in all the other cases.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Joona Kiiski 2009-10-17 08:42:42 +03:00 • committed by Marco Costalba
parent 4dd7fccfd1
commit f0b0a3b135
2 changed files with 42 additions and 9 deletions
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48
src/search.cpp
View file

@ -308,7 +308,9 @@ namespace {
bool thread_is_available(int slave, int master);
bool idle_thread_exists(int master);
bool split(const Position& pos, SearchStack* ss, int ply,
Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
Value *alpha, Value *beta, Value *bestValue,
const Value futilityValue, const Value approximateValue,
Depth depth, int *moves,
MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode);
void wake_sleeping_threads();
@ -1176,7 +1178,7 @@ namespace {
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
&& split(pos, ss, ply, &alpha, &beta, &bestValue, depth,
&& split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE, VALUE_NONE, depth,
&moveCount, &mp, dcCandidates, threadID, true))
break;
}
@ -1437,7 +1439,7 @@ namespace {
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
&& split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount,
&& split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval, depth, &moveCount,
&mp, dcCandidates, threadID, false))
break;
}
@ -1693,10 +1695,37 @@ namespace {
if ( useFutilityPruning
&& !dangerous
&& !moveIsCapture
&& !move_is_promotion(move)
&& moveCount >= 2 + int(sp->depth)
&& ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
continue;
&& !move_is_promotion(move))
{
// History pruning. See ok_to_prune() definition
if ( moveCount >= 2 + int(sp->depth)
&& ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth)
&& sp->bestValue > value_mated_in(PLY_MAX))
continue;
// Value based pruning
if (sp->approximateEval < sp->beta)
{
if (sp->futilityValue == VALUE_NONE)
{
EvalInfo ei;
sp->futilityValue = evaluate(pos, ei, threadID)
+ FutilityMargins[int(sp->depth) - 2];
}
if (sp->futilityValue < sp->beta)
{
if (sp->futilityValue > sp->bestValue) // Less then 1% of cases
{
lock_grab(&(sp->lock));
if (sp->futilityValue > sp->bestValue)
sp->bestValue = sp->futilityValue;
lock_release(&(sp->lock));
}
continue;
}
}
}
// Make and search the move.
StateInfo st;
@ -2756,7 +2785,8 @@ namespace {
// splitPoint->cpus becomes 0), split() returns true.
bool split(const Position& p, SearchStack* sstck, int ply,
Value* alpha, Value* beta, Value* bestValue, Depth depth, int* moves,
Value* alpha, Value* beta, Value* bestValue, const Value futilityValue,
const Value approximateEval, Depth depth, int* moves,
MovePicker* mp, Bitboard dcCandidates, int master, bool pvNode) {
assert(p.is_ok());
@ -2796,6 +2826,8 @@ namespace {
splitPoint->pvNode = pvNode;
splitPoint->dcCandidates = dcCandidates;
splitPoint->bestValue = *bestValue;
splitPoint->futilityValue = futilityValue;
splitPoint->approximateEval = approximateEval;
splitPoint->master = master;
splitPoint->mp = mp;
splitPoint->moves = *moves;

3
src/thread.h
View file

@ -50,7 +50,8 @@ struct SplitPoint {
SearchStack *parentSstack;
int ply;
Depth depth;
volatile Value alpha, beta, bestValue;
volatile Value alpha, beta, bestValue, futilityValue;
Value approximateEval;
bool pvNode;
Bitboard dcCandidates;
int master, slaves[THREAD_MAX];