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Code Issues Releases Wiki Activity

Simplify aspiration window code

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Here the main difference is that now we center
aspiration window on last returned score. This allows
to simplify handling of mate scores.

We have done a reversed SPRT tests, where we wanted to
verify if master is stronger than this patch.

Long TC: master vs this patch (reverse test)
LLR: -2.95 (-2.94,2.94)
Total: 37992 W: 7012 L: 6920 D: 24060

bench: 4507288
This commit is contained in:
Marco Costalba 2013-07-03 18:58:49 +02:00
parent 838255ef91
commit a55fb76dcc
1 changed files with 25 additions and 34 deletions
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59
src/search.cpp
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@ -296,9 +296,12 @@ namespace {
Value bestValue, alpha, beta, delta;
memset(ss-1, 0, 4 * sizeof(Stack));
depth = BestMoveChanges = 0;
bestValue = delta = -VALUE_INFINITE;
(ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
depth = BestMoveChanges = 0;
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
TT.new_search();
History.clear();
Gains.clear();
@ -328,17 +331,12 @@ namespace {
// MultiPV loop. We perform a full root search for each PV line
for (PVIdx = 0; PVIdx < PVSize; PVIdx++)
{
// Set aspiration window default width
if (depth >= 5 && abs(RootMoves[PVIdx].prevScore) < VALUE_KNOWN_WIN)
// Reset aspiration window starting size
if (depth >= 5)
{
delta = Value(16);
alpha = RootMoves[PVIdx].prevScore - delta;
beta = RootMoves[PVIdx].prevScore + delta;
}
else
{
alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
alpha = std::max(RootMoves[PVIdx].prevScore - delta,-VALUE_INFINITE);
beta = std::min(RootMoves[PVIdx].prevScore + delta, VALUE_INFINITE);
}
// Start with a small aspiration window and, in case of fail high/low,
@ -366,35 +364,28 @@ namespace {
if (Signals.stop)
return;
// In case of failing high/low increase aspiration window and
// In case of failing low/high increase aspiration window and
// research, otherwise exit the loop.
if (bestValue > alpha && bestValue < beta)
if (bestValue <= alpha)
{
alpha = std::max(bestValue - delta, -VALUE_INFINITE);
Signals.failedLowAtRoot = true;
Signals.stopOnPonderhit = false;
}
else if (bestValue >= beta)
beta = std::min(bestValue + delta, VALUE_INFINITE);
else
break;
delta += delta / 2;
assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
// Give some update (without cluttering the UI) before to research
if (Time::now() - SearchTime > 3000)
sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
if (abs(bestValue) >= VALUE_KNOWN_WIN)
{
alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
}
else if (bestValue >= beta)
{
beta += delta;
delta += delta / 2;
}
else
{
Signals.failedLowAtRoot = true;
Signals.stopOnPonderhit = false;
alpha -= delta;
delta += delta / 2;
}
assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
}
// Sort the PV lines searched so far and update the GUI