smaller TEntry and different replacement strategy (#98)

Bench: 621764
Disservin · Jun 29, 2022 · 08d7bc9 · 08d7bc9
1 parent 5e0ecbf
commit 08d7bc9
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Showing 4 changed files with 15 additions and 24 deletions.
diff --git a/src/search.cpp b/src/search.cpp
@@ -366,7 +366,7 @@ int Search::absearch(int depth, int alpha, int beta, int ply, Stack *ss) {
         UpdateHH(bestMove, depth, quietMoves);
 
     // Store position in TT
-    if (!exit_early()) store_entry(depth, best, oldAlpha, beta, board.hashKey, startAge, bestMove.get());
+    if (!exit_early()) store_entry(depth, best, oldAlpha, beta, board.hashKey, bestMove.get());
     return best;
 }
 
@@ -413,7 +413,6 @@ int Search::iterative_deepening(int search_depth, uint64_t maxN, Time time) {
     maxNodes = maxN;
 
     // TT starting age of this searches entries
-    startAge = board.fullMoveNumber;
 
     int result = 0;
     Move prev_bestmove{};

diff --git a/src/search.h b/src/search.h
@@ -46,8 +46,7 @@ class Search {
     // bestmove
     Move bestMove{};
 
-    // startAge and seldepth
-    uint16_t startAge{};
+    //seldepth
     uint8_t seldepth{};
 
     // move ordering and time usage

diff --git a/src/tt.cpp b/src/tt.cpp
@@ -1,30 +1,24 @@
 #include "tt.h"
 
-bool store_entry(int depth, int bestvalue,
+void store_entry(int depth, int bestvalue,
                  int old_alpha, int beta, U64 key,
-                 uint16_t startAge, uint16_t move) {
-    U64 index = key % TT_SIZE;                
+                 uint16_t move) 
+{
+    U64  index = key % TT_SIZE;                
     TEntry tte = TTable[index];
-    if (!(bestvalue >= 19000) && !(bestvalue <= -19000) &&
-        (tte.depth < depth || tte.age + 3 <= startAge)) {
-        tte.flag = EXACT;
-        // Upperbound
-        if (bestvalue <= old_alpha) {
-            tte.flag = UPPERBOUND;
-        }
-        // Lowerbound
-        else if (bestvalue >= beta) {
-            tte.flag = LOWERBOUND;
-        }
+
+    Flag b = bestvalue <= old_alpha ? UPPERBOUND : bestvalue >= beta ? LOWERBOUND : EXACT;
+
+    if (bestvalue < 19000 && bestvalue > -19000
+        && (tte.key != key || b == EXACT || depth > (tte.depth * 2) / 3)) 
+    {
         tte.depth = depth;
         tte.score = bestvalue;
-        tte.age = startAge;
         tte.key = key;
         tte.move = move;
+        tte.flag = b;
         TTable[index] = tte;
-        return true;
     }
-    return false;
 }
 
 void probe_tt(TEntry &tte, bool &ttHit, U64 key, int depth)

diff --git a/src/tt.h b/src/tt.h
@@ -5,16 +5,15 @@ struct TEntry {
 	U64 key;
 	int score;
 	uint16_t move;
-	uint16_t age;
 	uint8_t depth;
 	Flag flag;
 }__attribute__((packed));
 
 extern TEntry* TTable;
 extern U64 TT_SIZE;
 
-bool store_entry(int depth, int bestvalue,
+void store_entry(int depth, int bestvalue,
                  int old_alpha, int beta, U64 key,
-                 uint16_t startAge, uint16_t move);
+                 uint16_t move);
 
 void probe_tt(TEntry &tte, bool &ttHit, U64 key, int depth);