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Use simple array for Pawns Connected bonus #2061

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Simplification which removes the pawns connected array.
Instead of storing the values in an array, the values are
calculated real-time. This is about 1.6% faster on my machines.

Performance:
master ave nps: 159,248,672
patch ave nps: 161,905,592

STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 20363 W: 4579 L: 4455 D: 11329
http://tests.stockfishchess.org/tests/view/5c9925ba0ebc5925cfff79a6

Non functional change.
This commit is contained in:
protonspring 2019-03-25 13:04:14 -06:00 • committed by Marco Costalba
parent 76f1807baa
commit 95ba7f78d5
3 changed files with 8 additions and 27 deletions
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1
src/main.cpp
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@ -42,7 +42,6 @@ int main(int argc, char* argv[]) {
Position::init();
Bitbases::init();
Search::init();
Pawns::init();
Threads.set(Options["Threads"]);
Search::clear(); // After threads are up

33
src/pawns.cpp
View file

@ -35,8 +35,8 @@ namespace {
constexpr Score Doubled = S(11, 56);
constexpr Score Isolated = S( 5, 15);
// Connected pawn bonus by opposed, phalanx, #support and rank
Score Connected[2][2][3][RANK_NB];
// Connected pawn bonus
constexpr int Connected[RANK_NB] = { 0, 13, 24, 18, 65, 100, 175, 330 };
// Strength of pawn shelter for our king by [distance from edge][rank].
// RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
@ -128,8 +128,12 @@ namespace {
// Score this pawn
if (support | phalanx)
score += Connected[opposed][bool(phalanx)][popcount(support)][relative_rank(Us, s)];
{
int r = relative_rank(Us, s);
int v = phalanx ? Connected[r] + Connected[r + 1] : 2 * Connected[r];
v = 17 * popcount(support) + (v >> (opposed + 1));
score += make_score(v, v * (r - 2) / 4);
}
else if (!neighbours)
score -= Isolated, e->weakUnopposed[Us] += !opposed;
@ -147,27 +151,6 @@ namespace {
namespace Pawns {
/// Pawns::init() initializes some tables needed by evaluation. Instead of using
/// hard-coded tables, when makes sense, we prefer to calculate them with a formula
/// to reduce independent parameters and to allow easier tuning and better insight.
void init() {
static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 65, 100, 175, 330 };
for (int opposed = 0; opposed <= 1; ++opposed)
for (int phalanx = 0; phalanx <= 1; ++phalanx)
for (int support = 0; support <= 2; ++support)
for (Rank r = RANK_2; r < RANK_8; ++r)
{
int v = 17 * support;
v += (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4);
}
}
/// Pawns::probe() looks up the current position's pawns configuration in
/// the pawns hash table. It returns a pointer to the Entry if the position
/// is found. Otherwise a new Entry is computed and stored there, so we don't

1
src/pawns.h
View file

@ -76,7 +76,6 @@ struct Entry {
typedef HashTable<Entry, 16384> Table;
void init();
Entry* probe(const Position& pos);
} // namespace Pawns