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continuation histories when in check

Browse source 
If in check, don't write to continuation histories ss-4, ss-6.
Adding inCheck to the stack was needed, and might be useful for
future patches.

Passed STC:
https://tests.stockfishchess.org/tests/view/5e9ee24acaaff5d60a50b812
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 61774 W: 11725 L: 11449 D: 38600
Ptnml(0-2): 971, 7211, 14322, 7337, 1046

Passed LTC:
https://tests.stockfishchess.org/tests/view/5e9eecb7caaff5d60a50b831
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 250822 W: 32067 L: 31179 D: 187576
Ptnml(0-2): 1745, 23126, 74824, 23928, 1788

closes https://github.com/official-stockfish/Stockfish/pull/2645

bench: 4808463
This commit is contained in:
pb00067 2020-04-21 20:55:41 +02:00 • committed by Joost VandeVondele
parent 221893bf67
commit bb5589b829
2 changed files with 23 additions and 18 deletions
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40
src/search.cpp
View file

@ -626,14 +626,14 @@ namespace {
Move ttMove, move, excludedMove, bestMove;
Depth extension, newDepth;
Value bestValue, value, ttValue, eval, maxValue;
bool ttHit, ttPv, formerPv, inCheck, givesCheck, improving, didLMR, priorCapture;
bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR;
Piece movedPiece;
int moveCount, captureCount, quietCount;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
ss->inCheck = pos.checkers();
priorCapture = pos.captured_piece();
Color us = pos.side_to_move();
moveCount = captureCount = quietCount = ss->moveCount = 0;
@ -654,7 +654,7 @@ namespace {
if ( Threads.stop.load(std::memory_order_relaxed)
|| pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos)
return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos)
: value_draw(pos.this_thread());
// Step 3. Mate distance pruning. Even if we mate at the next move our score
@ -793,7 +793,7 @@ namespace {
CapturePieceToHistory& captureHistory = thisThread->captureHistory;
// Step 6. Static evaluation of the position
if (inCheck)
if (ss->inCheck)
{
ss->staticEval = eval = VALUE_NONE;
improving = false;
@ -920,7 +920,7 @@ namespace {
probCutCount++;
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[inCheck]
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[pos.moved_piece(move)]
[to_sq(move)];
@ -1030,7 +1030,7 @@ moves_loop: // When in check, search starts from here
// Futility pruning: parent node (~5 Elo)
if ( lmrDepth < 6
&& !inCheck
&& !ss->inCheck
&& ss->staticEval + 235 + 172 * lmrDepth <= alpha
&& (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]
@ -1146,7 +1146,7 @@ moves_loop: // When in check, search starts from here
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[inCheck]
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[movedPiece]
[to_sq(move)];
@ -1365,11 +1365,11 @@ moves_loop: // When in check, search starts from here
// must be a mate or a stalemate. If we are in a singular extension search then
// return a fail low score.
assert(moveCount || !inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
assert(moveCount || !ss->inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
if (!moveCount)
bestValue = excludedMove ? alpha
: inCheck ? mated_in(ss->ply) : VALUE_DRAW;
: ss->inCheck ? mated_in(ss->ply) : VALUE_DRAW;
else if (bestMove)
update_all_stats(pos, ss, bestMove, bestValue, beta, prevSq,
@ -1413,7 +1413,7 @@ moves_loop: // When in check, search starts from here
Move ttMove, move, bestMove;
Depth ttDepth;
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
bool ttHit, pvHit, inCheck, givesCheck, captureOrPromotion;
bool ttHit, pvHit, givesCheck, captureOrPromotion;
int moveCount;
if (PvNode)
@ -1426,20 +1426,20 @@ moves_loop: // When in check, search starts from here
Thread* thisThread = pos.this_thread();
(ss+1)->ply = ss->ply + 1;
bestMove = MOVE_NONE;
inCheck = pos.checkers();
ss->inCheck = pos.checkers();
moveCount = 0;
// Check for an immediate draw or maximum ply reached
if ( pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : VALUE_DRAW;
return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos) : VALUE_DRAW;
assert(0 <= ss->ply && ss->ply < MAX_PLY);
// Decide whether or not to include checks: this fixes also the type of
// TT entry depth that we are going to use. Note that in qsearch we use
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
ttDepth = ss->inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
: DEPTH_QS_NO_CHECKS;
// Transposition table lookup
posKey = pos.key();
@ -1457,7 +1457,7 @@ moves_loop: // When in check, search starts from here
return ttValue;
// Evaluate the position statically
if (inCheck)
if (ss->inCheck)
{
ss->staticEval = VALUE_NONE;
bestValue = futilityBase = -VALUE_INFINITE;
@ -1520,7 +1520,7 @@ moves_loop: // When in check, search starts from here
moveCount++;
// Futility pruning
if ( !inCheck
if ( !ss->inCheck
&& !givesCheck
&& futilityBase > -VALUE_KNOWN_WIN
&& !pos.advanced_pawn_push(move))
@ -1543,7 +1543,7 @@ moves_loop: // When in check, search starts from here
}
// Don't search moves with negative SEE values
if ( !inCheck && !pos.see_ge(move))
if ( !ss->inCheck && !pos.see_ge(move))
continue;
// Speculative prefetch as early as possible
@ -1557,7 +1557,7 @@ moves_loop: // When in check, search starts from here
}
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[inCheck]
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[pos.moved_piece(move)]
[to_sq(move)];
@ -1591,7 +1591,7 @@ moves_loop: // When in check, search starts from here
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
if (inCheck && bestValue == -VALUE_INFINITE)
if (ss->inCheck && bestValue == -VALUE_INFINITE)
return mated_in(ss->ply); // Plies to mate from the root
tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit,
@ -1710,8 +1710,12 @@ moves_loop: // When in check, search starts from here
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
for (int i : {1, 2, 4, 6})
{
if (ss->inCheck && i > 2)
break;
if (is_ok((ss-i)->currentMove))
(*(ss-i)->continuationHistory)[pc][to] << bonus;
}
}

1
src/search.h
View file

@ -49,6 +49,7 @@ struct Stack {
Value staticEval;
int statScore;
int moveCount;
bool inCheck;
};