Attempt #1

jhonnold · May 24, 2021 · 93c2985 · 93c2985
1 parent 48546fb
commit 93c2985
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Showing 4 changed files with 67 additions and 75 deletions.
diff --git a/src/movegen.c b/src/movegen.c
@@ -564,8 +564,9 @@ void GenerateAllMoves(MoveList* moveList, Board* board, SearchData* data) {
   }
 
   // Get the hash move for sorting
-  TTValue ttValue = TTProbe(board->zobrist); // TODO: Don't I know this already from the search?
-  Move hashMove = TTMove(ttValue);
+  int ttHit;
+  TTEntry* tt = TTProbe(&ttHit, board->zobrist); // TODO: Don't I know this already from the search?
+  Move hashMove = ttHit ? tt->move : NULL_MOVE;
 
   for (int i = 0; i < moveList->count; i++) {
     Move move = moveList->moves[i];

diff --git a/src/search.c b/src/search.c
@@ -212,15 +212,16 @@ int Negamax(int alpha, int beta, int depth, ThreadData* thread, PV* pv) {
 
   // check the transposition table for previous info
   // we ignore the tt on singular extension searches
-  TTValue ttValue = skipMove ? NO_ENTRY : TTProbe(board->zobrist);
+  int ttHit = 0;
+  TTEntry* tt = skipMove ? NULL : TTProbe(&ttHit, board->zobrist);
 
   // if the TT has a value that fits our position and has been searched to an equal or greater depth, then we accept
   // this score and prune
-  if (!isPV && ttValue && TTDepth(ttValue) >= depth) {
-    int ttScore = TTScore(ttValue, data->ply);
-    int flag = TTFlag(ttValue);
+  if (!isPV && ttHit && tt->depth >= depth) {
+    int ttScore = TTScore(tt, data->ply);
 
-    if (flag == TT_EXACT || (flag == TT_LOWER && ttScore >= beta) || (flag == TT_UPPER && ttScore <= alpha))
+    if ((tt->flags & TT_EXACT) || ((tt->flags & TT_LOWER) && ttScore >= beta) ||
+        ((tt->flags & TT_UPPER) && ttScore <= alpha))
       return ttScore;
   }
 
@@ -248,14 +249,14 @@ int Negamax(int alpha, int beta, int depth, ThreadData* thread, PV* pv) {
       }
 
       // if the tablebase gives us what we want, then we accept it's score and return
-      if (flag == TT_EXACT || (flag == TT_LOWER && score >= beta) || (flag == TT_UPPER && score <= alpha)) {
+      if ((flag & TT_EXACT) || ((flag & TT_LOWER) && score >= beta) || ((flag & TT_UPPER) && score <= alpha)) {
         TTPut(board->zobrist, depth, score, flag, 0, data->ply, 0);
         return score;
       }
 
       // for pv node searches we adjust our a/b search accordingly
       if (isPV) {
-        if (flag == TT_LOWER) {
+        if (flag & TT_LOWER) {
           bestScore = score;
           alpha = max(alpha, score);
         } else
@@ -265,7 +266,7 @@ int Negamax(int alpha, int beta, int depth, ThreadData* thread, PV* pv) {
   }
 
   // pull previous static eval from tt - this is depth independent
-  int eval = data->evals[data->ply] = (ttValue ? TTEval(ttValue) : Evaluate(board, thread));
+  int eval = data->evals[data->ply] = (ttHit ? tt->eval : Evaluate(board, thread));
   // getting better if eval has gone up
   int improving = data->ply >= 2 && (data->evals[data->ply] > data->evals[data->ply - 2]);
 
@@ -276,9 +277,9 @@ int Negamax(int alpha, int beta, int depth, ThreadData* thread, PV* pv) {
 
   if (!isPV && !board->checkers) {
     // Our TT might have a more accurate evaluation score, use this
-    if (ttValue && TTDepth(ttValue) >= depth) {
-      int ttScore = TTScore(ttValue, data->ply);
-      if (TTFlag(ttValue) == (ttScore > eval ? TT_LOWER : TT_UPPER))
+    if (ttHit && tt->depth >= depth) {
+      int ttScore = TTScore(tt, data->ply);
+      if (tt->flags & (ttScore > eval ? TT_LOWER : TT_UPPER))
         eval = ttScore;
     }
 
@@ -311,7 +312,7 @@ int Negamax(int alpha, int beta, int depth, ThreadData* thread, PV* pv) {
     // less than beta + margin, then we run a shallow search to look
     int probBeta = beta + 100;
     if (depth > 4 && abs(beta) < MATE_BOUND &&
-        !(ttValue && TTDepth(ttValue) >= depth - 3 && TTScore(ttValue, data->ply) < probBeta)) {
+        !(ttHit && tt->depth >= depth - 3 && TTScore(tt, data->ply) < probBeta)) {
       MoveList moveList;
       GenerateTacticalMoves(&moveList, board);
 
@@ -339,7 +340,7 @@ int Negamax(int alpha, int beta, int depth, ThreadData* thread, PV* pv) {
 
   // IIR by Ed Schroder
   // http://talkchess.com/forum3/viewtopic.php?f=7&t=74769&sid=64085e3396554f0fba414404445b3120
-  if (depth >= 4 && !ttValue && !skipMove)
+  if (depth >= 4 && !ttHit && !skipMove)
     depth--;
 
   MoveList moveList;
@@ -385,9 +386,9 @@ int Negamax(int alpha, int beta, int depth, ThreadData* thread, PV* pv) {
     // moves at a shallow depth on a nullwindow that is somewhere below the tt evaluation
     // implemented using "skip move" recursion like in SF (allows for reductions when doing singular search)
     int extension = 0;
-    if (depth >= 8 && !skipMove && !isRoot && move == TTMove(ttValue) && TTDepth(ttValue) >= depth - 3 &&
-        abs(TTScore(ttValue, data->ply)) < MATE_BOUND && TTFlag(ttValue) == TT_LOWER) {
-      int sBeta = max(TTScore(ttValue, data->ply) - depth * 2, -CHECKMATE);
+    if (depth >= 8 && !skipMove && !isRoot && ttHit && move == tt->move && tt->depth >= depth - 3 &&
+        abs(TTScore(tt, data->ply)) < MATE_BOUND && (tt->flags & TT_LOWER)) {
+      int sBeta = max(TTScore(tt, data->ply) - depth * 2, -CHECKMATE);
       int sDepth = depth / 2 - 1;
 
       data->skipMove[data->ply] = move;
@@ -529,23 +530,23 @@ int Quiesce(int alpha, int beta, ThreadData* thread, PV* pv) {
     return Evaluate(board, thread);
 
   // check the transposition table for previous info
-  TTValue ttValue = TTProbe(board->zobrist);
+  int ttHit = 0;
+  TTEntry* tt = TTProbe(&ttHit, board->zobrist);
   // TT score pruning - no depth check required since everything in QS is depth 0
-  if (ttValue) {
-    int score = TTScore(ttValue, data->ply);
-    int flag = TTFlag(ttValue);
-
-    if (flag == TT_EXACT || (flag == TT_LOWER && score >= beta) || (flag == TT_UPPER && score <= alpha))
-      return score;
+  if (ttHit) {
+    int ttScore = TTScore(tt, data->ply);
+    if ((tt->flags & TT_EXACT) || ((tt->flags & TT_LOWER) && ttScore >= beta) ||
+        ((tt->flags & TT_UPPER) && ttScore <= alpha))
+      return ttScore;
   }
 
   // pull cached eval if it exists
-  int eval = data->evals[data->ply] = (ttValue ? TTEval(ttValue) : Evaluate(board, thread));
+  int eval = data->evals[data->ply] = (ttHit ? tt->eval : Evaluate(board, thread));
 
   // can we use an improved evaluation from the tt?
-  if (ttValue) {
-    int ttEval = TTScore(ttValue, data->ply);
-    if (TTFlag(ttValue) == (ttEval > eval ? TT_LOWER : TT_UPPER))
+  if (ttHit) {
+    int ttEval = TTScore(tt, data->ply);
+    if (tt->flags & (ttEval > eval ? TT_LOWER : TT_UPPER))
       eval = ttEval;
   }
 

diff --git a/src/transposition.c b/src/transposition.c
@@ -40,7 +40,7 @@ size_t TTInit(int mb) {
   uint64_t keySize = (uint64_t)log2(mb) + (uint64_t)log2(MEGABYTE / sizeof(TTBucket));
 
 #if defined(__linux__) && !defined(__ANDROID__)
-  // On Linux systems we align on 2MB boundaries and request Huge Pages 
+  // On Linux systems we align on 2MB boundaries and request Huge Pages
   TT.buckets = aligned_alloc(2 * MEGABYTE, (1ULL << keySize) * sizeof(TTBucket));
   madvise(TT.buckets, (1ULL << keySize) * sizeof(TTBucket), MADV_HUGEPAGE);
 #else
@@ -57,56 +57,56 @@ void TTFree() { free(TT.buckets); }
 
 inline void TTClear() { memset(TT.buckets, 0, (TT.mask + 1ULL) * sizeof(TTBucket)); }
 
-inline int TTScore(TTValue value, int ply) {
-  int score = (int)((int16_t)((value & 0x0000FFFF00000000) >> 32));
-
-  return score > MATE_BOUND ? score - ply : score < -MATE_BOUND ? score + ply : score;
+inline int TTScore(TTEntry* e, int ply) {
+  return e->score > MATE_BOUND ? e->score - ply : e->score < -MATE_BOUND ? e->score + ply : e->score;
 }
 
 inline void TTPrefetch(uint64_t hash) { __builtin_prefetch(&TT.buckets[TT.mask & hash]); }
 
-inline TTValue TTProbe(uint64_t hash) {
-#ifdef TUNE
-  return NO_ENTRY;
-#else
-  TTBucket bucket = TT.buckets[TT.mask & hash];
+inline TTEntry* TTProbe(int* hit, uint64_t hash) {
+#ifndef TUNE
+  TTBucket* bucket = &TT.buckets[TT.mask & hash];
+  uint32_t shortHash = hash >> 32;
 
   for (int i = 0; i < BUCKET_SIZE; i++)
-    if (bucket.entries[i].hash == hash)
-      return bucket.entries[i].value;
-
-  return NO_ENTRY;
+    if (bucket->entries[i].hash == shortHash) {
+      *hit = 1;
+      return &bucket->entries[i];
+    }
 #endif
+
+  return 0;
 }
 
-inline TTValue TTPut(uint64_t hash, int depth, int score, int flag, Move move, int ply, int eval) {
+inline void TTPut(uint64_t hash, uint8_t depth, int16_t score, uint8_t flag, Move move, int ply, int16_t eval) {
 #ifdef TUNE
-  return NO_ENTRY;
+  return;
 #else
 
-  TTBucket* bucket = &TT.buckets[TT.mask & hash];
+  TTBucket bucket = TT.buckets[TT.mask & hash];
+  uint32_t shortHash = hash >> 32;
+
   int replacementDepth = INT32_MAX;
   int replacementIdx = 0;
 
   for (int i = 0; i < BUCKET_SIZE; i++) {
-    TTEntry entry = bucket->entries[i];
+    TTEntry entry = bucket.entries[i];
     if (!entry.hash) {
       replacementIdx = i;
       break;
     }
 
-    int currDepth = TTDepth(entry.value);
-    if (entry.hash == hash) {
-      if (currDepth > depth && flag != TT_EXACT)
-        return entry.value;
+    if (entry.hash == shortHash) {
+      if (entry.depth > depth && !(flag & TT_EXACT))
+        return;
 
       replacementIdx = i;
       break;
     }
 
-    if (currDepth < replacementDepth) {
+    if (entry.depth < replacementDepth) {
       replacementIdx = i;
-      replacementDepth = currDepth;
+      replacementDepth = entry.depth;
     }
   }
 
@@ -116,10 +116,8 @@ inline TTValue TTPut(uint64_t hash, int depth, int score, int flag, Move move, i
   else if (score < -MATE_BOUND)
     adjustedScore -= ply;
 
-  bucket->entries[replacementIdx].hash = hash;
-  TTValue tt = bucket->entries[replacementIdx].value = TTEntry(adjustedScore, flag, depth, move, eval);
-
-  return tt;
+  TTEntry* entry = &bucket.entries[replacementIdx];
+  *entry = (TTEntry){.flags = flag, .depth = depth, .eval = eval, .score = score, .hash = shortHash, .move = move};
 #endif
 }
 

diff --git a/src/transposition.h b/src/transposition.h
@@ -19,17 +19,17 @@
 
 #include "types.h"
 
-
-
 #define NO_ENTRY 0ULL
 #define MEGABYTE 0x100000ULL
 #define BUCKET_SIZE 3
 
-typedef uint64_t TTValue;
-
 typedef struct {
-  uint64_t hash;
-  TTValue value;
+  uint8_t flags;
+  uint8_t depth;
+  int16_t eval;
+  int16_t score;
+  uint32_t hash;
+  Move move;
 } TTEntry;
 
 typedef struct {
@@ -44,25 +44,17 @@ typedef struct {
   uint64_t size;
 } TTTable;
 
-enum { TT_LOWER, TT_UPPER, TT_EXACT };
+enum { TT_LOWER = 1, TT_UPPER = 2, TT_EXACT = 4 };
 
 extern TTTable TT;
 
-#define TTEntry(score, flag, depth, move, eval)                                                                        \
-  ((TTValue)((uint16_t)(eval)) << 48) | ((TTValue)((uint16_t)(score)) << 32) | ((TTValue)(flag) << 30) |               \
-      ((TTValue)(depth) << 24) | ((TTValue)(move))
-#define TTFlag(value) ((int)((unsigned)((value)&0xC0000000) >> 30))
-#define TTMove(value) ((Move)((value)&0xFFFFFF))
-#define TTDepth(value) ((int)((value)&0x3F000000) >> 24)
-#define TTEval(value) ((int)((int16_t)((value) >> 48)))
-
 size_t TTInit(int mb);
 void TTFree();
 void TTClear();
 void TTPrefetch(uint64_t hash);
-TTValue TTProbe(uint64_t hash);
-int TTScore(TTValue value, int ply);
-TTValue TTPut(uint64_t hash, int depth, int score, int flag, Move move, int ply, int eval);
+TTEntry* TTProbe(int* hit, uint64_t hash);
+int TTScore(TTEntry* e, int ply);
+void TTPut(uint64_t hash, uint8_t depth, int16_t score, uint8_t flag, Move move, int ply, int16_t eval);
 int TTFull();
 
 #endif