Stockfish 1.7.1

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/depth.h

@@ -27,7 +27,8 @@
 
 enum Depth {
   DEPTH_ZERO = 0,
-  DEPTH_MAX = 200  // 100 * OnePly;
+  DEPTH_MAX = 200, // 100 * OnePly;
+  DEPTH_ENSURE_SIGNED = -1
 };
 
 

src/misc.cpp

@@ -41,20 +41,20 @@
 
 #include <cassert>
 #include <cstdio>
-#include <cstring>
 #include <iomanip>
 #include <iostream>
 #include <sstream>
 
 #include "bitcount.h"
 #include "misc.h"
+#include "thread.h"
 
 using namespace std;
 
 /// Version number. If this is left empty, the current date (in the format
 /// YYMMDD) is used as a version number.
 
-static const string EngineVersion = "1.7";
+static const string EngineVersion = "1.7.1";
 static const string AppName = "Stockfish";
 static const string AppTag  = "";
 
@@ -183,85 +183,39 @@ int get_system_time() {
 }
 
 
-/// builtin_cpu_count() tries to detect the number of CPU cores, if
-/// hyper-threading is enabled this is the number of logical processors.
+/// cpu_count() tries to detect the number of CPU cores.
 
 #if !defined(_MSC_VER)
 
 #  if defined(_SC_NPROCESSORS_ONLN)
-static int builtin_cpu_count() {
-  return Min(sysconf(_SC_NPROCESSORS_ONLN), 8);
+int cpu_count() {
+  return Min(sysconf(_SC_NPROCESSORS_ONLN), MAX_THREADS);
 }
 #  elif defined(__hpux)
-static int builtin_cpu_count() {
+int cpu_count() {
   struct pst_dynamic psd;
   if (pstat_getdynamic(&psd, sizeof(psd), (size_t)1, 0) == -1)
       return 1;
 
-  return Min(psd.psd_proc_cnt, 8);
+  return Min(psd.psd_proc_cnt, MAX_THREADS);
 }
 #  else
-static int builtin_cpu_count() {
+int cpu_count() {
   return 1;
 }
 #  endif
 
 #else
 
-static int builtin_cpu_count() {
+int cpu_count() {
   SYSTEM_INFO s;
   GetSystemInfo(&s);
-  return Min(s.dwNumberOfProcessors, 8);
+  return Min(s.dwNumberOfProcessors, MAX_THREADS);
 }
 
 #endif
 
 
-/// HT_enabled() returns true if hyper-threading is enabled on current machine
-
-static bool HT_enabled() {
-
-  char CPUString[0x20];
-  int CPUInfo[4] = {-1};
-  int nIds, nLogicalCPU, nCores;
-
-  // Detect CPU producer
-  __cpuid(CPUInfo, 0);
-  nIds = CPUInfo[0];
-
-  memset(CPUString, 0, sizeof(CPUString));
-  memcpy(&CPUString[0], &CPUInfo[1], sizeof(int));
-  memcpy(&CPUString[4], &CPUInfo[3], sizeof(int));
-  memcpy(&CPUString[8], &CPUInfo[2], sizeof(int));
-
-  // Not an Intel CPU or CPUID.4 not supported
-  if (strcmp(CPUString, "GenuineIntel") || nIds < 4)
-      return false;
-
-  // Detect if HT Technology is supported
-  __cpuid(CPUInfo, 1);
-  if (!((CPUInfo[3] >> 28) & 1))
-      return false;
-
-  nLogicalCPU = (CPUInfo[1] >> 16) & 0xFF;
-
-  // Detect number of cores
-  __cpuid(CPUInfo, 4);
-  nCores = 1 + ((CPUInfo[0] >> 26) & 0x3F);
-
-  return nLogicalCPU > nCores;
-}
-
-
-/// cpu_count() tries to detect the number of physical CPU cores taking
-/// in account hyper-threading.
-
-int cpu_count() {
-
-  return HT_enabled() ? builtin_cpu_count() / 2 : builtin_cpu_count();
-}
-
-
 /*
   From Beowulf, from Olithink
 */

src/search.cpp

@@ -257,7 +257,7 @@ namespace {
   int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime;
   int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
   bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
-  bool FirstRootMove, AbortSearch, Quit, AspirationFailLow;
+  bool FirstRootMove, AbortSearch, Quit, AspirationFailLow, ZugDetection;
 
   // Log file
   bool UseLogFile;
@@ -294,7 +294,7 @@ namespace {
   Depth extension(const Position&, Move, bool, bool, bool, bool, bool, bool*);
   bool ok_to_do_nullmove(const Position& pos);
   bool ok_to_prune(const Position& pos, Move m, Move threat);
-  bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
+  bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove);
   Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
   void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
   void update_killers(Move m, SearchStack& ss);
@@ -425,6 +425,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
   MultiPV                 = get_option_value_int("MultiPV");
   Chess960                = get_option_value_bool("UCI_Chess960");
   UseLogFile              = get_option_value_bool("Use Search Log");
+  ZugDetection            = get_option_value_bool("Zugzwang detection"); // To be removed after 1.7.1
 
   if (UseLogFile)
       LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
@@ -1299,7 +1300,7 @@ namespace {
     tte = TT.retrieve(posKey);
     ttMove = (tte ? tte->move() : MOVE_NONE);
 
-    if (tte && ok_to_use_TT(tte, depth, beta, ply))
+    if (tte && ok_to_use_TT(tte, depth, beta, ply, allowNullmove))
     {
         ss[ply].currentMove = ttMove; // Can be MOVE_NONE
         return value_from_tt(tte->value(), ply);
@@ -1388,7 +1389,7 @@ namespace {
             {
                 assert(value_to_tt(nullValue, ply) == nullValue);
 
-                TT.store(posKey, nullValue, VALUE_TYPE_LOWER, depth, MOVE_NONE);
+                TT.store(posKey, nullValue, VALUE_TYPE_NS_LO, depth, MOVE_NONE);
                 return nullValue;
             }
         } else {
@@ -1625,7 +1626,7 @@ namespace {
     tte = TT.retrieve(pos.get_key());
     ttMove = (tte ? tte->move() : MOVE_NONE);
 
-    if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply))
+    if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply, true))
     {
         assert(tte->type() != VALUE_TYPE_EVAL);
 
@@ -1666,7 +1667,7 @@ namespace {
         alpha = bestValue;
 
     // If we are near beta then try to get a cutoff pushing checks a bit further
-    bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8;
+    bool deepChecks = (depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8);
 
     // Initialize a MovePicker object for the current position, and prepare
     // to search the moves. Because the depth is <= 0 here, only captures,
@@ -2306,14 +2307,18 @@ namespace {
   }
 
 
-  // ok_to_use_TT() returns true if a transposition table score
-  // can be used at a given point in search.
+  // ok_to_use_TT() returns true if a transposition table score can be used at a
+  // given point in search. To avoid zugzwang issues TT cutoffs at the root node
+  // of a null move verification search are not allowed if the TT value was found
+  // by a null search, this is implemented testing allowNullmove and TT entry type.
 
-  bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) {
+  bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove) {
 
     Value v = value_from_tt(tte->value(), ply);
 
-    return   (   tte->depth() >= depth
+    return   (allowNullmove || !(tte->type() & VALUE_TYPE_NULL) || !ZugDetection)
+
+          && (   tte->depth() >= depth
               || v >= Max(value_mate_in(PLY_MAX), beta)
               || v < Min(value_mated_in(PLY_MAX), beta))
 

src/tt.h

@@ -46,8 +46,8 @@
 /// the 32 bits of the data field are so defined
 ///
 /// bit  0-16: move
-/// bit 17-19: not used
-/// bit 20-22: value type
+/// bit 17-18: not used
+/// bit 19-22: value type
 /// bit 23-31: generation
 
 class TTEntry {
@@ -55,14 +55,14 @@ class TTEntry {
 public:
   TTEntry() {}
   TTEntry(uint32_t k, Value v, ValueType t, Depth d, Move m, int generation)
-        : key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)),
+        : key_ (k), data((m & 0x1FFFF) | (t << 19) | (generation << 23)),
           value_(int16_t(v)), depth_(int16_t(d)) {}
 
   uint32_t key() const { return key_; }
   Depth depth() const { return Depth(depth_); }
   Move move() const { return Move(data & 0x1FFFF); }
   Value value() const { return Value(value_); }
-  ValueType type() const { return ValueType((data >> 20) & 7); }
+  ValueType type() const { return ValueType((data >> 19) & 0xF); }
   int generation() const { return (data >> 23); }
 
 private:

src/ucioption.cpp

@@ -113,6 +113,9 @@ namespace {
     o["UCI_Chess960"] = Option(false);
     o["UCI_AnalyseMode"] = Option(false);
 
+    // Temporary hack for 1.7.1 to be removed in next release
+    o["Zugzwang detection"] = Option(false);
+
     // Any option should know its name so to be easily printed
     for (Options::iterator it = o.begin(); it != o.end(); ++it)
         it->second.name = it->first;

src/value.h

@@ -33,13 +33,16 @@
 ////
 
 enum ValueType {
-  VALUE_TYPE_NONE = 0,
+  VALUE_TYPE_NONE =  0,
   VALUE_TYPE_UPPER = 1,  // Upper bound
   VALUE_TYPE_LOWER = 2,  // Lower bound
   VALUE_TYPE_EXACT = 3,  // Exact score
-  VALUE_TYPE_EVAL  = 4,  // Evaluation cache
-  VALUE_TYPE_EV_UP = 5,  // Evaluation cache for upper bound
-  VALUE_TYPE_EV_LO = 6   // Evaluation cache for lower bound
+  VALUE_TYPE_EVAL  = 4,  // Static evaluation value
+  VALUE_TYPE_NULL  = 8,  // Null search value
+
+  VALUE_TYPE_EV_UP = VALUE_TYPE_EVAL | VALUE_TYPE_UPPER,
+  VALUE_TYPE_EV_LO = VALUE_TYPE_EVAL | VALUE_TYPE_LOWER,
+  VALUE_TYPE_NS_LO = VALUE_TYPE_NULL | VALUE_TYPE_LOWER,
 };