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Increase pruning if evaluation is not improving

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Add an additional set of margins to movecount pruning
to be used when static evaluation is getting worse
than previous move.

Here are the margins table with changing
depth (fm0 not improving, fm1 improving):

    d: 0, fm0: 3, fm1: 3
    d: 1, fm0: 4, fm1: 4
    d: 2, fm0: 6, fm1: 6
    d: 3, fm0: 7, fm1: 10
    d: 4, fm0: 11, fm1: 15
    d: 5, fm0: 15, fm1: 21
    d: 6, fm0: 21, fm1: 29
    d: 7, fm0: 27, fm1: 37
    d: 8, fm0: 35, fm1: 47
    d: 9, fm0: 42, fm1: 57
    d: 10, fm0: 51, fm1: 68
    d: 11, fm0: 60, fm1: 81
    d: 12, fm0: 70, fm1: 94
    d: 13, fm0: 81, fm1: 108
    d: 14, fm0: 92, fm1: 123
    d: 15, fm0: 104, fm1: 139

Good at both short TC

LLR: 2.97 (-2.94,2.94)
Total: 11502 W: 2503 L: 2361 D: 6638

And long TC

LLR: 2.98 (-2.94,2.94)
Total: 7189 W: 1421 L: 1277 D: 4491

bench: 4364793
This commit is contained in:
Eelco de Groot 2013-07-29 01:16:25 +02:00 • committed by Marco Costalba
parent d30dfc084c
commit 5ee16a180a
2 changed files with 16 additions and 11 deletions
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25
src/search.cpp
View file

@ -66,7 +66,7 @@ namespace {
// Futility lookup tables (initialized at startup) and their access functions // Futility lookup tables (initialized at startup) and their access functions
Value FutilityMargins[16][64]; // [depth][moveNumber] Value FutilityMargins[16][64]; // [depth][moveNumber]
int FutilityMoveCounts[32]; // [depth] int FutilityMoveCounts[2][32]; // [improving][depth]
inline Value futility_margin(Depth d, int mn) { inline Value futility_margin(Depth d, int mn) {
@ -146,7 +146,11 @@ void Search::init() {
// Init futility move count array // Init futility move count array
for (d = 0; d < 32; d++) for (d = 0; d < 32; d++)
FutilityMoveCounts[d] = int(3.001 + 0.3 * pow(double(d), 1.8)); {
FutilityMoveCounts[1][d] = int(3.001 + 0.3 * pow(double(d), 1.8));
FutilityMoveCounts[0][d] = d < 5 ? FutilityMoveCounts[1][d]
: 3 * FutilityMoveCounts[1][d] / 4;
}
} }
@ -294,11 +298,11 @@ namespace {
void id_loop(Position& pos) { void id_loop(Position& pos) {
Stack stack[MAX_PLY_PLUS_2], *ss = stack+1; // To allow referencing (ss-1) Stack stack[MAX_PLY_PLUS_3], *ss = stack+2; // To allow referencing (ss-2)
int depth, prevBestMoveChanges; int depth, prevBestMoveChanges;
Value bestValue, alpha, beta, delta; Value bestValue, alpha, beta, delta;
std::memset(ss-1, 0, 4 * sizeof(Stack)); std::memset(ss-2, 0, 5 * sizeof(Stack));
(ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
depth = BestMoveChanges = 0; depth = BestMoveChanges = 0;
@ -496,7 +500,7 @@ namespace {
Depth ext, newDepth; Depth ext, newDepth;
Value bestValue, value, ttValue; Value bestValue, value, ttValue;
Value eval, nullValue, futilityValue; Value eval, nullValue, futilityValue;
bool inCheck, givesCheck, pvMove, singularExtensionNode; bool inCheck, givesCheck, pvMove, singularExtensionNode, improving;
bool captureOrPromotion, dangerous, doFullDepthSearch; bool captureOrPromotion, dangerous, doFullDepthSearch;
int moveCount, quietCount; int moveCount, quietCount;
@ -765,6 +769,7 @@ moves_loop: // When in check and at SpNode search starts from here
MovePicker mp(pos, ttMove, depth, History, countermoves, ss); MovePicker mp(pos, ttMove, depth, History, countermoves, ss);
CheckInfo ci(pos); CheckInfo ci(pos);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
improving = ss->staticEval >= (ss-2)->staticEval;
singularExtensionNode = !RootNode singularExtensionNode = !RootNode
&& !SpNode && !SpNode
&& depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY) && depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY)
@ -861,7 +866,7 @@ moves_loop: // When in check and at SpNode search starts from here
{ {
// Move count based pruning // Move count based pruning
if ( depth < 16 * ONE_PLY if ( depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[depth] && moveCount >= FutilityMoveCounts[improving][depth]
&& (!threatMove || !refutes(pos, move, threatMove))) && (!threatMove || !refutes(pos, move, threatMove)))
{ {
if (SpNode) if (SpNode)
@ -1562,7 +1567,7 @@ moves_loop: // When in check and at SpNode search starts from here
void RootMove::extract_pv_from_tt(Position& pos) { void RootMove::extract_pv_from_tt(Position& pos) {
StateInfo state[MAX_PLY_PLUS_2], *st = state; StateInfo state[MAX_PLY_PLUS_3], *st = state;
const TTEntry* tte; const TTEntry* tte;
int ply = 0; int ply = 0;
Move m = pv[0]; Move m = pv[0];
@ -1595,7 +1600,7 @@ void RootMove::extract_pv_from_tt(Position& pos) {
void RootMove::insert_pv_in_tt(Position& pos) { void RootMove::insert_pv_in_tt(Position& pos) {
StateInfo state[MAX_PLY_PLUS_2], *st = state; StateInfo state[MAX_PLY_PLUS_3], *st = state;
const TTEntry* tte; const TTEntry* tte;
int ply = 0; int ply = 0;
@ -1670,10 +1675,10 @@ void Thread::idle_loop() {
Threads.mutex.unlock(); Threads.mutex.unlock();
Stack stack[MAX_PLY_PLUS_2], *ss = stack+1; // To allow referencing (ss-1) Stack stack[MAX_PLY_PLUS_3], *ss = stack+2; // To allow referencing (ss-2)
Position pos(*sp->pos, this); Position pos(*sp->pos, this);
std::memcpy(ss-1, sp->ss-1, 4 * sizeof(Stack)); std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack));
ss->splitPoint = sp; ss->splitPoint = sp;
sp->mutex.lock(); sp->mutex.lock();

2
src/types.h
View file

@ -90,7 +90,7 @@ typedef uint64_t Bitboard;
const int MAX_MOVES = 192; const int MAX_MOVES = 192;
const int MAX_PLY = 100; const int MAX_PLY = 100;
const int MAX_PLY_PLUS_2 = MAX_PLY + 2; const int MAX_PLY_PLUS_3 = MAX_PLY + 3;
/// A move needs 16 bits to be stored /// A move needs 16 bits to be stored
/// ///