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MaxGain based pruning

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Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Joona Kiiski 2010-01-21 22:13:02 +02:00 • committed by Marco Costalba
parent 05a8c318b8
commit 5b2fc1e1c0
1 changed files with 19 additions and 6 deletions
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25
src/search.cpp
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@ -1403,7 +1403,7 @@ namespace {
// Calculate depth dependant futility pruning parameters
const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8));
const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2);
const int PostFutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2);
// Evaluate the position statically
if (!isCheck)
@ -1417,7 +1417,7 @@ namespace {
}
ss[ply].eval = staticValue;
futilityValue = staticValue + FutilityValueMargin;
futilityValue = staticValue + PostFutilityValueMargin; //FIXME: Remove me, only for split
staticValue = refine_eval(tte, staticValue, ply); // Enhance accuracy with TT value if possible
// Store gain statistics
@ -1430,8 +1430,8 @@ namespace {
}
// Post futility pruning
if (staticValue - FutilityValueMargin >= beta)
return (staticValue - FutilityValueMargin);
if (staticValue - PostFutilityValueMargin >= beta)
return (staticValue - PostFutilityValueMargin);
// Null move search
if ( allowNullmove
@ -1570,7 +1570,20 @@ namespace {
continue;
// Value based pruning
futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
Depth predictedDepth = newDepth;
//FIXME HACK: awful code duplication
double red = 0.5 + ln(moveCount) * ln(depth / 2) / 3.0;
if (red >= 1.0)
predictedDepth -= int(floor(red * int(OnePly)));
int preFutilityValueMargin = 0;
if (predictedDepth >= OnePly)
preFutilityValueMargin = 112 * bitScanReverse32(int(predictedDepth) * int(predictedDepth) / 2);
preFutilityValueMargin += MG.retrieve(pos.piece_on(move_from(move)), move_from(move), move_to(move)) + 45;
futilityValueScaled = ss[ply].eval + preFutilityValueMargin - moveCount * IncrementalFutilityMargin;
if (futilityValueScaled < beta)
{
@ -1631,7 +1644,7 @@ namespace {
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
&& split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue,
&& split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, //FIXME: SMP & futilityValue
depth, &moveCount, &mp, threadID, false))
break;
}