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Reorder conditions in LMR and pruning

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Make code logic somewhat easier to follow.

closes https://github.com/official-stockfish/Stockfish/pull/3285

No functional change.
This commit is contained in:
Vizvezdenec
2021-01-01 12:59:35 +03:00
committed by Joost VandeVondele
parent 23c385ec36
commit 2c1be0be8e
1 changed files with 22 additions and 22 deletions
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src/search.cpp
+22 -22
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@@ -1039,8 +1039,20 @@ moves_loop: // When in check, search starts from here
// Reduced depth of the next LMR search // Reduced depth of the next LMR search
int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0); int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
if ( !captureOrPromotion if ( captureOrPromotion
&& !givesCheck) || givesCheck)
{
// Capture history based pruning when the move doesn't give check
if ( !givesCheck
&& lmrDepth < 1
&& captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0)
continue;
// SEE based pruning
if (!pos.see_ge(move, Value(-218) * depth)) // (~25 Elo)
continue;
}
else
{ {
// Countermoves based pruning (~20 Elo) // Countermoves based pruning (~20 Elo)
if ( lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1) if ( lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
@@ -1062,18 +1074,6 @@ moves_loop: // When in check, search starts from here
if (!pos.see_ge(move, Value(-(30 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth))) if (!pos.see_ge(move, Value(-(30 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
continue; continue;
} }
else
{
// Capture history based pruning when the move doesn't give check
if ( !givesCheck
&& lmrDepth < 1
&& captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0)
continue;
// SEE based pruning
if (!pos.see_ge(move, Value(-218) * depth)) // (~25 Elo)
continue;
}
} }
// Step 13. Extensions (~75 Elo) // Step 13. Extensions (~75 Elo)
@@ -1192,7 +1192,14 @@ moves_loop: // When in check, search starts from here
if (singularQuietLMR) if (singularQuietLMR)
r--; r--;
if (!captureOrPromotion) if (captureOrPromotion)
{
// Unless giving check, this capture is likely bad
if ( !givesCheck
&& ss->staticEval + PieceValue[EG][pos.captured_piece()] + 210 * depth <= alpha)
r++;
}
else
{ {
// Increase reduction if ttMove is a capture (~5 Elo) // Increase reduction if ttMove is a capture (~5 Elo)
if (ttCapture) if (ttCapture)
@@ -1228,13 +1235,6 @@ moves_loop: // When in check, search starts from here
// Decrease/increase reduction for moves with a good/bad history (~30 Elo) // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
r -= ss->statScore / 14884; r -= ss->statScore / 14884;
} }
else
{
// Unless giving check, this capture is likely bad
if ( !givesCheck
&& ss->staticEval + PieceValue[EG][pos.captured_piece()] + 210 * depth <= alpha)
r++;
}
Depth d = std::clamp(newDepth - r, 1, newDepth); Depth d = std::clamp(newDepth - r, 1, newDepth);