Cleanup MAX_PLY

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index ea1ed57ab0846068d1d9d182c4115837a3b15e98..f6cf7090f1e2dfd681a8d3b2bac3540a62c55228 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -240,7 +240,7 @@ namespace {
 
   void id_loop(Position& pos) {
 
-    Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2)
+    Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2)
     int depth;
     Value bestValue, alpha, beta, delta;
 
@@ -265,7 +265,7 @@ namespace {
     multiPV = std::max(multiPV, skill.candidates_size());
 
     // Iterative deepening loop until requested to stop or target depth reached
-    while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth))
+    while (++depth < MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth))
     {
         // Age out PV variability metric
         BestMoveChanges *= 0.5;
@@ -430,10 +430,7 @@ namespace {
 
     moveCount = quietCount = 0;
     bestValue = -VALUE_INFINITE;
-    ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
     ss->ply = (ss-1)->ply + 1;
-    (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
-    (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
 
     // Used to send selDepth info to GUI
     if (PvNode && thisThread->maxPly < ss->ply)
@@ -442,8 +439,8 @@ namespace {
     if (!RootNode)
     {
         // Step 2. Check for aborted search and immediate draw
-        if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY)
-            return ss->ply > MAX_PLY && !inCheck ? evaluate(pos) : DrawValue[pos.side_to_move()];
+        if (Signals.stop || pos.is_draw() || ss->ply >= MAX_PLY)
+            return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos) : DrawValue[pos.side_to_move()];
 
         // Step 3. Mate distance pruning. Even if we mate at the next move our score
         // would be at best mate_in(ss->ply+1), but if alpha is already bigger because
@@ -457,6 +454,12 @@ namespace {
             return alpha;
     }
 
+    assert(0 <= ss->ply && ss->ply < MAX_PLY);
+
+    ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
+    (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
+    (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
+
     // Step 4. Transposition table lookup
     // We don't want the score of a partial search to overwrite a previous full search
     // TT value, so we use a different position key in case of an excluded move.
@@ -1021,8 +1024,10 @@ moves_loop: // When in check and at SpNode search starts from here
     ss->ply = (ss-1)->ply + 1;
 
     // Check for an instant draw or if the maximum ply has been reached
-    if (pos.is_draw() || ss->ply > MAX_PLY)
-        return ss->ply > MAX_PLY && !InCheck ? evaluate(pos) : DrawValue[pos.side_to_move()];
+    if (pos.is_draw() || ss->ply >= MAX_PLY)
+        return ss->ply >= MAX_PLY && !InCheck ? evaluate(pos) : DrawValue[pos.side_to_move()];
+
+    assert(0 <= ss->ply && ss->ply < MAX_PLY);
 
     // Decide whether or not to include checks: this fixes also the type of
     // TT entry depth that we are going to use. Note that in qsearch we use
@@ -1352,7 +1357,7 @@ moves_loop: // When in check and at SpNode search starts from here
 
 void RootMove::extract_pv_from_tt(Position& pos) {
 
-  StateInfo state[MAX_PLY_PLUS_6], *st = state;
+  StateInfo state[MAX_PLY], *st = state;
   const TTEntry* tte;
   int ply = 1;    // At root ply is 1...
   Move m = pv[0]; // ...instead pv[] array starts from 0
@@ -1388,7 +1393,7 @@ void RootMove::extract_pv_from_tt(Position& pos) {
 
 void RootMove::insert_pv_in_tt(Position& pos) {
 
-  StateInfo state[MAX_PLY_PLUS_6], *st = state;
+  StateInfo state[MAX_PLY], *st = state;
   const TTEntry* tte;
   int idx = 0; // Ply starts from 1, we need to start from 0
 
@@ -1430,7 +1435,7 @@ void Thread::idle_loop() {
 
           Threads.mutex.unlock();
 
-          Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2)
+          Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2)
           Position pos(*sp->pos, this);
 
           std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack));