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Correctly reset bestMoveChanges

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for searches not using time management (e.g. analysis, fixed node game play etc),
bestMoveChanges was not reset during search iterations. As LMR uses this quantity,
search was somewhat weaker.

Tested using fixed node playing games:
```
./c-chess-cli -each nodes=10000 option.Hash=16 -engine cmd=../Stockfish/src/fix -engine cmd=../Stockfish/src/master -concurrency 6 -openings file=../books/UHO_XXL_+0.90_+1.19.epd -games 10000
Score of Stockfish Fix vs Stockfish Master: 3187 - 3028 - 3785  [0.508] 10000

./c-chess-cli -each nodes=30000 option.Hash=16 -engine cmd=../Stockfish/src/fix -engine cmd=../Stockfish/src/master -concurrency 6 -openings file=../books/UHO_XXL_+0.90_+1.19.epd -games 10000
Score of Stockfish Fix vs Stockfish Master: 2946 - 2834 - 4220  [0.506] 10000
```

closes https://github.com/official-stockfish/Stockfish/pull/3818

bench: 5061979
This commit is contained in:
bmc4
2021-11-29 14:51:35 -03:00
committed by Joost VandeVondele
parent 95a2ac1e07
commit c1f9a359e8
1 changed files with 7 additions and 7 deletions
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src/search.cpp
+7 -7
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@@ -477,6 +477,13 @@ void Thread::search() {
if (skill.enabled() && skill.time_to_pick(rootDepth))
skill.pick_best(multiPV);
// Use part of the gained time from a previous stable move for the current move
for (Thread* th : Threads)
{
totBestMoveChanges += th->bestMoveChanges;
th->bestMoveChanges = 0;
}
// Do we have time for the next iteration? Can we stop searching now?
if ( Limits.use_time_management()
&& !Threads.stop
@@ -489,13 +496,6 @@ void Thread::search() {
// If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.92 : 0.95;
double reduction = (1.47 + mainThread->previousTimeReduction) / (2.32 * timeReduction);
// Use part of the gained time from a previous stable move for the current move
for (Thread* th : Threads)
{
totBestMoveChanges += th->bestMoveChanges;
th->bestMoveChanges = 0;
}
double bestMoveInstability = 1.073 + std::max(1.0, 2.25 - 9.9 / rootDepth)
* totBestMoveChanges / Threads.size();
double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability;