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SE depth scaling using the previous depth

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This patch makes the SE depth condition more robust and allows it to scale with completed depth
from a previous search.

At long TC this patch is almost equivalent to https://github.com/official-stockfish/Stockfish/pull/4016 which had

VLTC:
https://tests.stockfishchess.org/tests/view/626abd7e8707aa698c0093a8
Elo: 2.35 +-1.5 (95%) LOS: 99.9%
Total: 40000 W: 10991 L: 10720 D: 18289
Ptnml(0-2): 8, 3534, 12648, 3799, 11
nElo: 5.47 +-3.4 (95%) PairsRatio: 1.08

VLTC multicore:
https://tests.stockfishchess.org/tests/view/6272a6afc8f14123163c1997
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 86808 W: 24165 L: 23814 D: 38829
Ptnml(0-2): 11, 7253, 28524, 7606, 10

however, it is now also gaining at LTC:

LTC:
https://tests.stockfishchess.org/tests/view/627e7cb523c0c72a05b651a9
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 27064 W: 7285 L: 7046 D: 12733
Ptnml(0-2): 8, 2446, 8390, 2675, 13

and should have nearly no influence at STC as depth 27 is rarely reached.
It was noticed that initializing the threshold with MAX_PLY, had an adverse effect,
possibly because the first move is sensitive to this.

closes https://github.com/official-stockfish/Stockfish/pull/4021
closes https://github.com/official-stockfish/Stockfish/pull/4016

Bench: 6481017
This commit is contained in:
disservin 2022-05-14 12:10:13 +02:00 • committed by Joost VandeVondele
parent c079acc26f
commit 5372f81cc8
4 changed files with 8 additions and 3 deletions
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1
AUTHORS
View file

@ -125,6 +125,7 @@ marotear
Matt Ginsberg (mattginsberg) Matt Ginsberg (mattginsberg)
Matthew Lai (matthewlai) Matthew Lai (matthewlai)
Matthew Sullivan (Matt14916) Matthew Sullivan (Matt14916)
Max A. (Disservin)
Maxim Molchanov (Maxim) Maxim Molchanov (Maxim)
Michael An (man) Michael An (man)
Michael Byrne (MichaelB7) Michael Byrne (MichaelB7)

5
src/search.cpp
View file

@ -238,6 +238,9 @@ void MainThread::search() {
bestPreviousScore = bestThread->rootMoves[0].score; bestPreviousScore = bestThread->rootMoves[0].score;
bestPreviousAverageScore = bestThread->rootMoves[0].averageScore; bestPreviousAverageScore = bestThread->rootMoves[0].averageScore;
for (Thread* th : Threads)
th->previousDepth = bestThread->completedDepth;
// Send again PV info if we have a new best thread // Send again PV info if we have a new best thread
if (bestThread != this) if (bestThread != this)
sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth, -VALUE_INFINITE, VALUE_INFINITE) << sync_endl; sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth, -VALUE_INFINITE, VALUE_INFINITE) << sync_endl;
@ -1061,7 +1064,7 @@ moves_loop: // When in check, search starts here
// a reduced search on all the other moves but the ttMove and if the // a reduced search on all the other moves but the ttMove and if the
// result is lower than ttValue minus a margin, then we will extend the ttMove. // result is lower than ttValue minus a margin, then we will extend the ttMove.
if ( !rootNode if ( !rootNode
&& depth >= 4 + 2 * (PvNode && tte->is_pv()) && depth >= 4 - (thisThread->previousDepth > 27) + 2 * (PvNode && tte->is_pv())
&& move == ttMove && move == ttMove
&& !excludedMove // Avoid recursive singular search && !excludedMove // Avoid recursive singular search
/* && ttValue != VALUE_NONE Already implicit in the next condition */ /* && ttValue != VALUE_NONE Already implicit in the next condition */

3
src/thread.cpp
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@ -60,7 +60,8 @@ void Thread::clear() {
counterMoves.fill(MOVE_NONE); counterMoves.fill(MOVE_NONE);
mainHistory.fill(0); mainHistory.fill(0);
captureHistory.fill(0); captureHistory.fill(0);
previousDepth = 0;
for (bool inCheck : { false, true }) for (bool inCheck : { false, true })
for (StatsType c : { NoCaptures, Captures }) for (StatsType c : { NoCaptures, Captures })
{ {

2
src/thread.h
View file

@ -69,7 +69,7 @@ public:
Position rootPos; Position rootPos;
StateInfo rootState; StateInfo rootState;
Search::RootMoves rootMoves; Search::RootMoves rootMoves;
Depth rootDepth, completedDepth, depth; Depth rootDepth, completedDepth, depth, previousDepth;
Value rootDelta; Value rootDelta;
CounterMoveHistory counterMoves; CounterMoveHistory counterMoves;
ButterflyHistory mainHistory; ButterflyHistory mainHistory;