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Code Issues Releases Wiki Activity

Better clarify how we use TT depth in qsearch

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Namely we use only two types of depth in TT:
DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-12-18 10:27:24 +01:00
parent 201e8d5f87
commit d55a5a4d81
3 changed files with 15 additions and 14 deletions
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5
src/depth.h
View file

@ -31,7 +31,10 @@ enum Depth {
ONE_PLY = 2, ONE_PLY = 2,
DEPTH_ZERO = 0, DEPTH_ZERO = 0 * ONE_PLY,
DEPTH_QS_CHECKS = -1 * ONE_PLY,
DEPTH_QS_NO_CHECKS = -2 * ONE_PLY,
DEPTH_NONE = -127 * ONE_PLY DEPTH_NONE = -127 * ONE_PLY
}; };

2
src/movepick.cpp
View file

@ -99,7 +99,7 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
phasePtr = MainSearchPhaseTable; phasePtr = MainSearchPhaseTable;
} }
else if (d == DEPTH_ZERO) else if (d >= DEPTH_QS_CHECKS)
phasePtr = QsearchWithChecksPhaseTable; phasePtr = QsearchWithChecksPhaseTable;
else else
{ {

22
src/search.cpp
View file

@ -1468,6 +1468,7 @@ split_point_start: // At split points actual search starts from here
Value bestValue, value, evalMargin, futilityValue, futilityBase; Value bestValue, value, evalMargin, futilityValue, futilityBase;
bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable; bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
const TTEntry* tte; const TTEntry* tte;
Depth ttDepth;
Value oldAlpha = alpha; Value oldAlpha = alpha;
ss->bestMove = ss->currentMove = MOVE_NONE; ss->bestMove = ss->currentMove = MOVE_NONE;
@ -1476,21 +1477,18 @@ split_point_start: // At split points actual search starts from here
if (pos.is_draw() || ply >= PLY_MAX - 1) if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW; return VALUE_DRAW;
// Decide whether or not to include checks // 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.
isCheck = pos.is_check(); isCheck = pos.is_check();
ttDepth = (isCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS);
Depth d;
if (isCheck || depth >= -ONE_PLY)
d = DEPTH_ZERO;
else
d = DEPTH_ZERO - ONE_PLY;
// Transposition table lookup. At PV nodes, we don't use the TT for // Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering. // pruning, but only for move ordering.
tte = TT.retrieve(pos.get_key()); tte = TT.retrieve(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE); ttMove = (tte ? tte->move() : MOVE_NONE);
if (!PvNode && tte && ok_to_use_TT(tte, d, beta, ply)) if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ply))
{ {
ss->bestMove = ttMove; // Can be MOVE_NONE ss->bestMove = ttMove; // Can be MOVE_NONE
return value_from_tt(tte->value(), ply); return value_from_tt(tte->value(), ply);
@ -1536,9 +1534,9 @@ split_point_start: // At split points actual search starts from here
// Initialize a MovePicker object for the current position, and prepare // Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures, // to search the moves. Because the depth is <= 0 here, only captures,
// queen promotions and checks (only if depth == 0 or depth == -ONE_PLY // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
// and we are near beta) will be generated. // be generated.
MovePicker mp = MovePicker(pos, ttMove, d, H); MovePicker mp = MovePicker(pos, ttMove, depth, H);
CheckInfo ci(pos); CheckInfo ci(pos);
// Loop through the moves until no moves remain or a beta cutoff occurs // Loop through the moves until no moves remain or a beta cutoff occurs
@ -1628,7 +1626,7 @@ split_point_start: // At split points actual search starts from here
// Update transposition table // Update transposition table
ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, d, ss->bestMove, ss->eval, evalMargin); TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, ttDepth, ss->bestMove, ss->eval, evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);