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Remove one reduction call
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even though bench is unchanged to depth 28,
due to adjusting depth in singular extensions this might be functional.

STC: https://tests.stockfishchess.org/tests/view/63ec21affe833123fef34153
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 195712 W: 51625 L: 51581 D: 92506
Ptnml(0-2): 504, 20527, 55779, 20513, 533

LTC: https://tests.stockfishchess.org/tests/view/63ed3487fe833123fef375ed
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 32176 W: 8631 L: 8442 D: 15103
Ptnml(0-2): 5, 2794, 10309, 2967, 13

closes #4395

Bench 4283297
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dubslow authored and vondele committed Feb 18, 2023
1 parent 085cace commit 037ef3e
Showing 1 changed file with 3 additions and 3 deletions.
6 changes: 3 additions & 3 deletions src/search.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -987,6 +987,8 @@ namespace {

Value delta = beta - alpha;

Depth r = reduction(improving, depth, moveCount, delta, thisThread->rootDelta);

// Step 14. Pruning at shallow depth (~120 Elo). Depth conditions are important for mate finding.
if ( !rootNode
&& pos.non_pawn_material(us)
Expand All @@ -996,7 +998,7 @@ namespace {
moveCountPruning = moveCount >= futility_move_count(improving, depth);

// Reduced depth of the next LMR search
int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount, delta, thisThread->rootDelta), 0);
int lmrDepth = std::max(newDepth - r, 0);

if ( capture
|| givesCheck)
Expand Down Expand Up @@ -1133,8 +1135,6 @@ namespace {
// Step 16. Make the move
pos.do_move(move, st, givesCheck);

Depth r = reduction(improving, depth, moveCount, delta, thisThread->rootDelta);

// Decrease reduction if position is or has been on the PV
// and node is not likely to fail low. (~3 Elo)
if ( ss->ttPv
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