tt size optimization

Author: Exclusivefrog28

main.cpp

@@ -201,6 +201,7 @@ int runPerft(int depth, const char* fen) {
 #endif
 
 int main() {
+
 #ifndef wasm
 	Interface::CLI interface;
 	interface.start();

src/Search.cpp

@@ -74,8 +74,8 @@ Move Search::search(ChessBoard&board, const int timeAllowed) {
 
 	if (search.lastPV.empty()) {
 		auto entry = tt.getEntry(board.hashCode, 0);
-		std::cout << "problem HASH: " << board.hashCode << " TT: key- " << entry.key << ", move- " << entry.bestMove << ", type- " << entry.nodeType <<
-				", depth- " << entry.depth << ", score- " << entry.score << std::endl;
+		std::cout << "problem HASH: " << board.hashCode << " TT: key- " << entry.key << ", move- " << entry.bestMove << ", type- " << entry.nodeType() <<
+				", depth- " << entry.depth() << ", score- " << entry.score() << std::endl;
 		return NULL_MOVE;
 	}
 
@@ -348,14 +348,14 @@ std::vector<Move> Search::collectPV(const int depth) const {
 	int pvDepth = 0;
 	while (tt.contains(board.hashCode)) {
 		const TranspositionTable::Entry entry = tt.getEntry(board.hashCode, 0);
-		if (entry.nodeType != TranspositionTable::EXACT) break;
+		if (entry.nodeType() != TranspositionTable::EXACT) break;
 		Move move = entry.bestMove;
 
 		if (pvPositions.contains(board.hashCode)) {
 			std::cout << "Cycle in PV!" << std::endl;
 			board.makeMove(move);
 			pv.push_back(move);
-			scores.push_back(entry.score);
+			scores.push_back(entry.score());
 			pvDepth++;
 			break;
 		}
@@ -381,7 +381,7 @@ std::vector<Move> Search::collectPV(const int depth) const {
 		pvPositions.insert(board.hashCode);
 		board.makeMove(move);
 		pv.push_back(move);
-		scores.push_back(entry.score);
+		scores.push_back(entry.score());
 		pvDepth++;
 	}
 	std::string pvString;
@@ -404,20 +404,20 @@ std::vector<Move> Search::collectPV(const int depth) const {
 bool Search::getTransposition(const uint64_t hash, const int depth, const int ply, int&score, const int&alpha, const int&beta, Move&hashMove) {
 	if (tt.contains(hash)) {
 		const TranspositionTable::Entry entry = tt.getEntry(hash, ply);
-		if (entry.depth >= depth) {
-			switch (entry.nodeType) {
+		if (entry.depth() >= depth) {
+			switch (entry.nodeType()) {
 				case TranspositionTable::EXACT:
-					score = entry.score;
+					score = entry.score();
 					return true;
 				case TranspositionTable::UPPERBOUND:
-					if (entry.score <= alpha) {
-						score = entry.score;
+					if (entry.score() <= alpha) {
+						score = entry.score();
 						return true;
 					}
 					break;
 				case TranspositionTable::LOWERBOUND:
-					if (entry.score >= beta) {
-						score = entry.score;
+					if (entry.score() >= beta) {
+						score = entry.score();
 						return true;
 					}
 				default: break;

src/TranspositionTable.cpp

@@ -1,6 +1,5 @@
 #include "TranspositionTable.h"
 #include <cmath>
-#include <cstdio>
 
 #include "MoveGenerator.h"
 
@@ -11,9 +10,9 @@ TranspositionTable::Entry TranspositionTable::getEntry(const uint64_t key, const
 	const int index = key % TT_SIZE;
 	Entry entry = entries[index];
 
-	if (abs(entry.score) >= MIN_MATE_SCORE) {
-		const int sign = entry.score > 0 ? 1 : -1;
-		entry.score = sign * (abs(entry.score) - ply);
+	if (abs(entry.score()) >= MIN_MATE_SCORE) {
+		const int sign = entry.score() > 0 ? 1 : -1;
+		entry.setScore(sign * (abs(entry.score()) - ply));
 	}
 	reads++;
 
@@ -22,7 +21,7 @@ TranspositionTable::Entry TranspositionTable::getEntry(const uint64_t key, const
 
 bool TranspositionTable::contains(const uint64_t key) {
 	const int index = key % TT_SIZE;
-	const bool exists = entries[index].nodeType != EMPTY;
+	const bool exists = entries[index].nodeType() != EMPTY;
 	const bool sameKey = (entries[index].key == key);
 	if (exists && !sameKey) collisions++;
 
@@ -37,17 +36,17 @@ void TranspositionTable::setEntry(const ChessBoard&board, const Move bestMove, c
 		score = sign * (abs(score) + ply);
 	}
 
-	const NodeType savedType = entries[index].nodeType;
+	const NodeType savedType = entries[index].nodeType();
 
-	const Entry entry = {board.hashCode, bestMove, depth, score, nodeType};
+	const Entry entry = Entry(board.hashCode, bestMove, depth, score, nodeType);
 
 	//REPLACEMENT SCHEME
 	// 1. Prefer EXACT nodes to bounds
 	// 2. Prefer deeper nodes to shallower
 
 	if (savedType != EMPTY) {
 		if ((savedType != EXACT && nodeType != EXACT) || (savedType == EXACT && nodeType == EXACT)) {
-			if (entries[index].depth <= depth) write(index, entry);
+			if (entries[index].depth() <= depth) write(index, entry);
 		}
 		else if (savedType != EXACT) write(index, entry);
 	}
@@ -68,14 +67,16 @@ void TranspositionTable::resetCounters() {
 int TranspositionTable::occupancy() const {
 	int occupied = 0;
 	for (int i = 0; i < TT_SIZE; i++) {
-		if (entries[i].nodeType != EMPTY) occupied++;
+		if (entries[i].nodeType() != EMPTY) occupied++;
 	}
 	return occupied;
 }
 
 void TranspositionTable::clear() {
 	resetCounters();
 	for (Entry&entry: entries) {
-		entry.nodeType = EMPTY;
+		entry.setNodeType(EMPTY);
 	}
 }
+
+TranspositionTable::TranspositionTable()= default;

src/TranspositionTable.h

@@ -18,31 +18,63 @@ class TranspositionTable {
         LOWERBOUND = 2,
         UPPERBOUND = 3,
     };
+
     struct Entry {
         uint64_t key;
-        Move bestMove;
-        int depth;
-        int score;
-        NodeType nodeType;
+        Move bestMove{};
+        uint32_t data;
+
+        uint8_t depth() const {
+            return (data & 0xFF0000) >> 16;
+        }
+
+        int16_t score() const {
+            return data & 0xFFFF;
+        }
+
+        void setScore(int16_t score) {
+            data = (data & 0xFFF0000) | score;
+        }
+
+        NodeType nodeType() const {
+            return (NodeType) ((data & 0xF000000) >> 24);
+        }
+
+        void setNodeType(NodeType nodeType) {
+            data = (data & 0x0FFFFFF) | (((uint8_t) nodeType) << 24);
+        }
+
+        Entry(uint64_t key, Move bestMove, int depth, int score, NodeType nodeType) {
+            this->key = key;
+            this->bestMove = bestMove;
+            this->data = 0 | (0xFFFF & ((int16_t) score)) | (((uint8_t) depth) << 16) | (((uint8_t) nodeType) << 24);
+        }
+
+        Entry() = default;
     };
 
+    TranspositionTable();
+
     bool contains(uint64_t key);
 
     Entry getEntry(uint64_t key, int ply);
 
-    void setEntry(const ChessBoard&board, Move bestMove, int depth, int score, NodeType nodeType, int ply);
+    void setEntry(const ChessBoard &board, Move bestMove, int depth, int score, NodeType nodeType, int ply);
 
     int reads;
     int writes;
     int collisions;
+
     void resetCounters();
+
     int occupancy() const;
+
     void clear();
 
     std::array<Entry, TT_SIZE> entries;
 
 private:
-    void write(int index, const Entry&entry);
+    void write(int index, const Entry &entry);
 
 
 };