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Codying style in accurate PV
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This is the first of a patch series to
rearrange and simplify accurate PV.

In this patch there is simple coding
style and reformatting stuff.

Verified with fishtest it does not crash
with MAX_PLY = 8

No functional change.
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@mcostalba
mcostalba committed Nov 18, 2014
1 parent 1a939cd commit 4aca11a
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Showing 2 changed files with 37 additions and 40 deletions.
62 changes: 36 additions & 26 deletions src/search.cpp
View file
Expand Up @@ -87,6 +87,7 @@ namespace {
void id_loop(Position& pos);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
void update_pv(Move* pv, Move move, Move* child);
void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
string uci_pv(const Position& pos, Depth depth, Value alpha, Value beta);

Expand Down Expand Up @@ -394,8 +395,7 @@ namespace {
assert(PvNode || (alpha == beta - 1));
assert(depth > DEPTH_ZERO);

PVEntry pv;
Move quietsSearched[64];
Move pv[MAX_PLY+1], quietsSearched[64];
StateInfo st;
const TTEntry *tte;
SplitPoint* splitPoint;
Expand Down Expand Up @@ -466,11 +466,8 @@ namespace {
ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;

// At PV nodes we check for exact scores, whilst at non-PV nodes we check for
// a fail high/low. The biggest advantage to probing at PV nodes is to have a
// smooth experience in analysis mode. We don't probe at Root nodes otherwise
// we should also update RootMoveList to avoid bogus output.
if ( !PvNode
// At non-PV nodes we check for a fail high/low. We don't probe at PV nodes
if ( !PvNode
&& tte
&& tte->depth() >= depth
&& ttValue != VALUE_NONE // Only in case of TT access race
Expand Down Expand Up @@ -865,14 +862,16 @@ namespace {
// 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
// parent node fail low with value <= alpha and to try another move.
if (PvNode && (moveCount == 1 || (value > alpha && (RootNode || value < beta)))) {
pv.pv[0] = MOVE_NONE;
(ss+1)->pv = &pv;
if (PvNode && (moveCount == 1 || (value > alpha && (RootNode || value < beta))))
{
pv[0] = MOVE_NONE;
(ss+1)->pv = pv;
value = newDepth < ONE_PLY ?
givesCheck ? -qsearch<PV, true>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
: -qsearch<PV, false>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
: - search<PV, false>(pos, ss+1, -beta, -alpha, newDepth, false);
}

// Step 17. Undo move
pos.undo_move(move);

Expand Down Expand Up @@ -901,8 +900,8 @@ namespace {
{
rm.score = value;
rm.pv.resize(1);
for (int i = 0; (ss+1)->pv && i < MAX_PLY && (ss+1)->pv->pv[i] != MOVE_NONE; ++i)
rm.pv.push_back((ss+1)->pv->pv[i]);
for (int i = 0; (ss+1)->pv && (ss+1)->pv[i] != MOVE_NONE; ++i)
rm.pv.push_back((ss+1)->pv[i]);

// We record how often the best move has been changed in each
// iteration. This information is used for time management: When
Expand All @@ -925,10 +924,11 @@ namespace {
{
bestMove = SpNode ? splitPoint->bestMove = move : move;

if (NT == PV) {
ss->pv->update(move, (ss+1)->pv);
if (PvNode && !RootNode)
{
update_pv(ss->pv, move, (ss+1)->pv);
if (SpNode)
splitPoint->ss->pv->update(move, (ss+1)->pv);
update_pv(splitPoint->ss->pv, move, (ss+1)->pv);
}

if (PvNode && value < beta) // Update alpha! Always alpha < beta
Expand Down Expand Up @@ -1015,7 +1015,7 @@ namespace {
assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);

PVEntry pv;
Move pv[MAX_PLY+1];
StateInfo st;
const TTEntry* tte;
Key posKey;
Expand All @@ -1024,12 +1024,11 @@ namespace {
bool givesCheck, evasionPrunable;
Depth ttDepth;

if (PvNode) {
// To flag BOUND_EXACT a node with eval above alpha and no available moves
oldAlpha = alpha;

(ss+1)->pv = &pv;
ss->pv->pv[0] = MOVE_NONE;
if (PvNode)
{
oldAlpha = alpha; // To flag BOUND_EXACT when eval above alpha and no available moves
(ss+1)->pv = pv;
ss->pv[0] = MOVE_NONE;
}

ss->currentMove = bestMove = MOVE_NONE;
Expand All @@ -1053,7 +1052,7 @@ namespace {
ttMove = tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;

if ( !PvNode
if ( !PvNode
&& tte
&& tte->depth() >= ttDepth
&& ttValue != VALUE_NONE // Only in case of TT access race
Expand Down Expand Up @@ -1181,7 +1180,7 @@ namespace {
if (value > alpha)
{
if (PvNode)
ss->pv->update(move, &pv);
update_pv(ss->pv, move, (ss+1)->pv);

if (PvNode && value < beta) // Update alpha here! Always alpha < beta
{
Expand Down Expand Up @@ -1239,6 +1238,15 @@ namespace {
}


// update_pv() copies child node pv[] adding current move

void update_pv(Move* pv, Move move, Move* child) {

for (*pv++ = move; child && *child != MOVE_NONE; )
*pv++ = *child++;
*pv = MOVE_NONE;
}

// update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high
// of a quiet move.

Expand Down Expand Up @@ -1371,15 +1379,17 @@ void RootMove::insert_pv_in_tt(Position& pos) {

StateInfo state[MAX_PLY], *st = state;
const TTEntry* tte;
int idx = 0;
size_t idx = 0;

for (; idx < int(pv.size()); ++idx) {
for ( ; idx < pv.size(); ++idx)
{
tte = TT.probe(pos.key());

if (!tte || tte->move() != pv[idx]) // Don't overwrite correct entries
TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[idx], VALUE_NONE);

assert(MoveList<LEGAL>(pos).contains(pv[idx]));

pos.do_move(pv[idx], *st++);
}

Expand Down
15 changes: 1 addition & 14 deletions src/search.h
View file
Expand Up @@ -32,26 +32,13 @@ struct SplitPoint;

namespace Search {

struct PVEntry {
Move pv[MAX_PLY+1];

void update(Move move, PVEntry* child) {
pv[0] = move;

int i = 1;
for (; child && i < MAX_PLY && child->pv[i - 1] != MOVE_NONE; ++i)
pv[i] = child->pv[i - 1];
pv[i] = MOVE_NONE;
}
};

/// The Stack struct keeps track of the information we need to remember from
/// nodes shallower and deeper in the tree during the search. Each search thread
/// has its own array of Stack objects, indexed by the current ply.

struct Stack {
SplitPoint* splitPoint;
PVEntry* pv;
Move* pv;
int ply;
Move currentMove;
Move ttMove;
Expand Down

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