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Remove skipEarlyPruning argument to search()

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Remove nine boolean arguments and the corresponding skipEarlyPruning variable.
Instead, skip early pruning only when there is an excluded move, and try null
move pruning only if the previous move was not itself a null move.

passed STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 33623 W: 6853 L: 6755 D: 20015
http://tests.stockfishchess.org/tests/view/5aef462a0ebc5902a409a10e

passed LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 39474 W: 5882 L: 5789 D: 27803
http://tests.stockfishchess.org/tests/view/5aefd4b80ebc5902a409a164

Closes https://github.com/official-stockfish/Stockfish/pull/1585

Bench: 4953556
This commit is contained in:
Joost VandeVondele 2018-05-08 10:43:46 +02:00 • committed by Stéphane Nicolet
parent 155d5417d9
commit 8d1625d6df
1 changed files with 13 additions and 14 deletions
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27
src/search.cpp
View file

@ -107,7 +107,7 @@ namespace {
}; };
template <NodeType NT> template <NodeType NT>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning); Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
template <NodeType NT> template <NodeType NT>
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = DEPTH_ZERO); Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = DEPTH_ZERO);
@ -390,7 +390,7 @@ void Thread::search() {
// high/low anymore. // high/low anymore.
while (true) while (true)
{ {
bestValue = ::search<PV>(rootPos, ss, alpha, beta, rootDepth, false, false); bestValue = ::search<PV>(rootPos, ss, alpha, beta, rootDepth, false);
// Bring the best move to the front. It is critical that sorting // Bring the best move to the front. It is critical that sorting
// is done with a stable algorithm because all the values but the // is done with a stable algorithm because all the values but the
@ -517,7 +517,7 @@ namespace {
// search<>() is the main search function for both PV and non-PV nodes // search<>() is the main search function for both PV and non-PV nodes
template <NodeType NT> template <NodeType NT>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning) { Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) {
// Use quiescence search when needed // Use quiescence search when needed
if (depth < ONE_PLY) if (depth < ONE_PLY)
@ -713,7 +713,7 @@ namespace {
improving = ss->staticEval >= (ss-2)->staticEval improving = ss->staticEval >= (ss-2)->staticEval
||(ss-2)->staticEval == VALUE_NONE; ||(ss-2)->staticEval == VALUE_NONE;
if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move())) if (ss->excludedMove || !pos.non_pawn_material(pos.side_to_move()))
goto moves_loop; goto moves_loop;
// Step 7. Razoring (skipped when in check, ~2 Elo) // Step 7. Razoring (skipped when in check, ~2 Elo)
@ -736,6 +736,7 @@ namespace {
// Step 9. Null move search with verification search (~40 Elo) // Step 9. Null move search with verification search (~40 Elo)
if ( !PvNode if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL
&& eval >= beta && eval >= beta
&& ss->staticEval >= beta - 36 * depth / ONE_PLY + 225 && ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
&& (ss->ply >= thisThread->nmp_ply || ss->ply % 2 != thisThread->nmp_odd)) && (ss->ply >= thisThread->nmp_ply || ss->ply % 2 != thisThread->nmp_odd))
@ -750,7 +751,7 @@ namespace {
pos.do_null_move(st); pos.do_null_move(st);
Value nullValue = -search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true); Value nullValue = -search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode);
pos.undo_null_move(); pos.undo_null_move();
@ -768,7 +769,7 @@ namespace {
thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4; thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4;
thisThread->nmp_odd = ss->ply % 2; thisThread->nmp_odd = ss->ply % 2;
Value v = search<NonPV>(pos, ss, beta-1, beta, depth-R, false, true); Value v = search<NonPV>(pos, ss, beta-1, beta, depth-R, false);
thisThread->nmp_odd = thisThread->nmp_ply = 0; thisThread->nmp_odd = thisThread->nmp_ply = 0;
@ -784,8 +785,6 @@ namespace {
&& depth >= 5 * ONE_PLY && depth >= 5 * ONE_PLY
&& abs(beta) < VALUE_MATE_IN_MAX_PLY) && abs(beta) < VALUE_MATE_IN_MAX_PLY)
{ {
assert(is_ok((ss-1)->currentMove));
Value rbeta = std::min(beta + 216 - 48 * improving, VALUE_INFINITE); Value rbeta = std::min(beta + 216 - 48 * improving, VALUE_INFINITE);
MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory); MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);
int probCutCount = 0; int probCutCount = 0;
@ -808,7 +807,7 @@ namespace {
// If the qsearch held perform the regular search // If the qsearch held perform the regular search
if (value >= rbeta) if (value >= rbeta)
value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false); value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode);
pos.undo_move(move); pos.undo_move(move);
@ -822,7 +821,7 @@ namespace {
&& !ttMove) && !ttMove)
{ {
Depth d = 3 * depth / 4 - 2 * ONE_PLY; Depth d = 3 * depth / 4 - 2 * ONE_PLY;
search<NT>(pos, ss, alpha, beta, d, cutNode, true); search<NT>(pos, ss, alpha, beta, d, cutNode);
tte = TT.probe(posKey, ttHit); tte = TT.probe(posKey, ttHit);
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
@ -897,7 +896,7 @@ moves_loop: // When in check, search starts from here
{ {
Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE); Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE);
ss->excludedMove = move; ss->excludedMove = move;
value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode, true); value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
ss->excludedMove = MOVE_NONE; ss->excludedMove = MOVE_NONE;
if (value < rBeta) if (value < rBeta)
@ -1027,7 +1026,7 @@ moves_loop: // When in check, search starts from here
Depth d = std::max(newDepth - r, ONE_PLY); Depth d = std::max(newDepth - r, ONE_PLY);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true, false); value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
doFullDepthSearch = (value > alpha && d != newDepth); doFullDepthSearch = (value > alpha && d != newDepth);
} }
@ -1036,7 +1035,7 @@ moves_loop: // When in check, search starts from here
// Step 17. Full depth search when LMR is skipped or fails high // Step 17. Full depth search when LMR is skipped or fails high
if (doFullDepthSearch) if (doFullDepthSearch)
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false); value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);
// For PV nodes only, do a full PV search on the first move or after a fail // For PV nodes only, do a full PV search on the first move or after a fail
// high (in the latter case search only if value < beta), otherwise let the // high (in the latter case search only if value < beta), otherwise let the
@ -1046,7 +1045,7 @@ moves_loop: // When in check, search starts from here
(ss+1)->pv = pv; (ss+1)->pv = pv;
(ss+1)->pv[0] = MOVE_NONE; (ss+1)->pv[0] = MOVE_NONE;
value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, false); value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false);
} }
// Step 18. Undo move // Step 18. Undo move