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Save static evaluation also for failed low nodes

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When a node fails low and bestValue is still equal to
the original static node evaluation, then save this
in TT along with usual info.

This will allow us to avoid a future costly evaluation() call.

This patch extends to failed low nodes what we already do
for failed high ones.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-09-18 10:32:57 +02:00
parent e145c0d3e2
commit 9741694fca
3 changed files with 12 additions and 6 deletions
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10
src/search.cpp
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@@ -1535,7 +1535,7 @@ namespace {
if (isCheck)
staticValue = -VALUE_INFINITE;
else if (tte && tte->type() == VALUE_TYPE_EVAL)
else if (tte && (tte->type() & VALUE_TYPE_EVAL))
{
// Use the cached evaluation score if possible
assert(ei.futilityMargin == Value(0));
@@ -1556,7 +1556,7 @@ namespace {
{
// Store the score to avoid a future costly evaluation() call
if (!isCheck && !tte && ei.futilityMargin == 0)
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EVAL, Depth(-127*OnePly), MOVE_NONE);
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE);
return bestValue;
}
@@ -1644,9 +1644,13 @@ namespace {
Move m = ss[ply].pv[ply];
if (!pvNode)
{
// If bestValue isn't changed it means it is still the static evaluation of
// the node, so keep this info to avoid a future costly evaluation() call.
ValueType type = (bestValue == staticValue && !ei.futilityMargin ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
if (bestValue < beta)
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE);
TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
else
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, m);
}