Rewrite bit counting functions

Get rid of macros and use templates instead,
this is safer and allows us fix the warning:

ISO C++ forbids braced-groups within expressions

That broke compilation with -pedantic flag under
gcc and POPCNT enabled.

No functional and no performance change.

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

src/Makefile

@@ -222,7 +222,7 @@ endif
 CXXFLAGS = -g -Wall -Wcast-qual -ansi -fno-exceptions -fno-rtti $(EXTRACXXFLAGS)
 
 ifeq ($(comp),gcc)
-	CXXFLAGS += -Wno-long-long -Wextra
+	CXXFLAGS += -pedantic -Wno-long-long -Wextra
 endif
 
 ifeq ($(comp),icc)

src/bitboard.cpp

@@ -404,7 +404,7 @@ namespace {
         }
 
     for (Bitboard b = 0ULL; b < 256ULL; b++)
-        BitCount8Bit[b] = (uint8_t)count_1s(b);
+        BitCount8Bit[b] = (uint8_t)count_1s<CNT32>(b);
   }
 
   int remove_bit_8(int i) { return ((i & ~15) >> 1) | (i & 7); }
@@ -494,7 +494,7 @@ namespace {
   Bitboard index_to_bitboard(int index, Bitboard mask) {
 
     Bitboard result = 0ULL;
-    int bits = count_1s(mask);
+    int bits = count_1s<CNT32>(mask);
 
     for (int i = 0; i < bits; i++)
     {

src/bitcount.h

@@ -24,27 +24,23 @@
 
 #include "types.h"
 
-// Select type of intrinsic bit count instruction to use, see
+enum BitCountType {
-// README.txt on how to pgo compile with POPCNT support.
+    CNT64,
-#if !defined(USE_POPCNT)
+    CNT64_MAX15,
-#define POPCNT_INTRINSIC(x) 0
+    CNT32,
-#elif defined(_MSC_VER)
+    CNT32_MAX15,
-#define POPCNT_INTRINSIC(x) (int)__popcnt64(x)
+    CNT_POPCNT
-#elif defined(__GNUC__)
+};
 
-#define POPCNT_INTRINSIC(x) ({ \
+/// count_1s() counts the number of nonzero bits in a bitboard.
-   unsigned long __ret; \
+/// We have different optimized versions according if platform
-   __asm__("popcnt %1, %0" : "=r" (__ret) : "r" (x)); \
+/// is 32 or 64 bits, and to the maximum number of nonzero bits.
-   __ret; })
+/// We also support hardware popcnt instruction. See Readme.txt
+/// on how to pgo compile with popcnt support.
+template<BitCountType> inline int count_1s(Bitboard);
 
-#endif
+template<>
-
+inline int count_1s<CNT64>(Bitboard b) {
-
-/// Software implementation of bit count functions
-
-#if defined(IS_64BIT)
-
-inline int count_1s(Bitboard b) {
   b -= ((b>>1) & 0x5555555555555555ULL);
   b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
   b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
@@ -52,16 +48,16 @@ inline int count_1s(Bitboard b) {
   return int(b >> 56);
 }
 
-inline int count_1s_max_15(Bitboard b) {
+template<>
+inline int count_1s<CNT64_MAX15>(Bitboard b) {
   b -= (b>>1) & 0x5555555555555555ULL;
   b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
   b *= 0x1111111111111111ULL;
   return int(b >> 60);
 }
 
-#else // if !defined(IS_64BIT)
+template<>
-
+inline int count_1s<CNT32>(Bitboard b) {
-inline int count_1s(Bitboard b) {
   unsigned w = unsigned(b >> 32), v = unsigned(b);
   v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
   w -= (w >> 1) & 0x55555555;
@@ -73,7 +69,8 @@ inline int count_1s(Bitboard b) {
   return int(v >> 24);
 }
 
-inline int count_1s_max_15(Bitboard b) {
+template<>
+inline int count_1s<CNT32_MAX15>(Bitboard b) {
   unsigned w = unsigned(b >> 32), v = unsigned(b);
   v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
   w -= (w >> 1) & 0x55555555;
@@ -84,27 +81,21 @@ inline int count_1s_max_15(Bitboard b) {
   return int(v >> 28);
 }
 
-#endif // BITCOUNT
+template<>
-
+inline int count_1s<CNT_POPCNT>(Bitboard b) {
-
+#if !defined(USE_POPCNT)
-/// count_1s() counts the number of nonzero bits in a bitboard.
+  return int(b != 0); // Avoid 'b not used' warning
-/// If template parameter is true an intrinsic is called, otherwise
+#elif defined(_MSC_VER)
-/// we fallback on a software implementation.
+  return __popcnt64(b);
-
+#elif defined(__GNUC__)
-template<bool UseIntrinsic>
+  unsigned long ret;
-inline int count_1s(Bitboard b) {
+  __asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
-
+  return ret;
-  return UseIntrinsic ? POPCNT_INTRINSIC(b) : count_1s(b);
+#endif
-}
-
-template<bool UseIntrinsic>
-inline int count_1s_max_15(Bitboard b) {
-
-  return UseIntrinsic ? POPCNT_INTRINSIC(b) : count_1s_max_15(b);
 }
 
 
-// Detect hardware POPCNT support
+/// cpu_has_popcnt() detects support for popcnt instruction at runtime
 inline bool cpu_has_popcnt() {
 
   int CPUInfo[4] = {-1};
@@ -113,9 +104,9 @@ inline bool cpu_has_popcnt() {
 }
 
 
-// Global constant initialized at startup that is set to true if
+/// CpuHasPOPCNT is a global constant initialized at startup that
-// CPU on which application runs supports POPCNT intrinsic. Unless
+/// is set to true if CPU on which application runs supports popcnt
-// USE_POPCNT is not defined.
+/// hardware instruction. Unless USE_POPCNT is not defined.
 #if defined(USE_POPCNT)
 const bool CpuHasPOPCNT = cpu_has_popcnt();
 #else
@@ -123,12 +114,12 @@ const bool CpuHasPOPCNT = false;
 #endif
 
 
-// Global constant used to print info about the use of 64 optimized
+/// CpuIs64Bit is a global constant initialized at compile time that
-// functions to verify that a 64 bit compile has been correctly built.
+/// is set to true if CPU on which application runs is a 64 bits.
 #if defined(IS_64BIT)
-const bool CpuHas64BitPath = true;
+const bool CpuIs64Bit = true;
 #else
-const bool CpuHas64BitPath = false;
+const bool CpuIs64Bit = false;
 #endif
 
 #endif // !defined(BITCOUNT_H_INCLUDED)

src/endgame.cpp

@@ -357,7 +357,7 @@ Value EvaluationFunction<KBBKN>::apply(const Position& pos) const {
   result += Value(square_distance(bksq, nsq) * 32);
 
   // Bonus for restricting the knight's mobility
-  result += Value((8 - count_1s_max_15(pos.attacks_from<KNIGHT>(nsq))) * 8);
+  result += Value((8 - count_1s<CNT32_MAX15>(pos.attacks_from<KNIGHT>(nsq))) * 8);
 
   return strongerSide == pos.side_to_move() ? result : -result;
 }

src/evaluate.cpp

@@ -439,6 +439,7 @@ namespace {
   template<Color Us, bool HasPopCnt>
   void init_eval_info(const Position& pos, EvalInfo& ei) {
 
+    const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
     Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
@@ -448,7 +449,7 @@ namespace {
     if (ei.updateKingTables[Us])
     {
         b &= ei.attackedBy[Us][PAWN];
-        ei.kingAttackersCount[Us] = b ? count_1s_max_15<HasPopCnt>(b) / 2 : EmptyBoardBB;
+        ei.kingAttackersCount[Us] = b ? count_1s<Max15>(b) / 2 : EmptyBoardBB;
         ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = EmptyBoardBB;
     }
   }
@@ -491,6 +492,8 @@ namespace {
     File f;
     Score bonus = SCORE_ZERO;
 
+    const BitCountType Full  = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64 : CNT32;
+    const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
     const Color Them = (Us == WHITE ? BLACK : WHITE);
     const Square* ptr = pos.piece_list_begin(Us, Piece);
 
@@ -518,12 +521,12 @@ namespace {
             ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
             Bitboard bb = (b & ei.attackedBy[Them][KING]);
             if (bb)
-                ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
+                ei.kingAdjacentZoneAttacksCount[Us] += count_1s<Max15>(bb);
         }
 
         // Mobility
-        mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & mobilityArea)
+        mob = (Piece != QUEEN ? count_1s<Max15>(b & mobilityArea)
-                              : count_1s<HasPopCnt>(b & mobilityArea));
+                              : count_1s<Full >(b & mobilityArea));
 
         mobility += MobilityBonus[Piece][mob];
 
@@ -652,6 +655,7 @@ namespace {
   template<Color Us, bool HasPopCnt>
   Score evaluate_king(const Position& pos, EvalInfo& ei, Value& margin) {
 
+    const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
     Bitboard undefended, b, b1, b2, safe;
@@ -680,7 +684,7 @@ namespace {
         // attacked and undefended squares around our king, the square of the
         // king, and the quality of the pawn shelter.
         attackUnits =  Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
-                     + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
+                     + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s<Max15>(undefended))
                      + InitKingDanger[relative_square(Us, ksq)]
                      - mg_value(ei.pi->king_shelter<Us>(pos, ksq)) / 32;
 
@@ -694,7 +698,7 @@ namespace {
                   | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
             if (b)
                 attackUnits +=  QueenContactCheckBonus
-                              * count_1s_max_15<HasPopCnt>(b)
+                              * count_1s<Max15>(b)
                               * (Them == pos.side_to_move() ? 2 : 1);
         }
 
@@ -712,7 +716,7 @@ namespace {
                   | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
             if (b)
                 attackUnits +=  RookContactCheckBonus
-                              * count_1s_max_15<HasPopCnt>(b)
+                              * count_1s<Max15>(b)
                               * (Them == pos.side_to_move() ? 2 : 1);
         }
 
@@ -725,22 +729,22 @@ namespace {
         // Enemy queen safe checks
         b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
         if (b)
-            attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b);
+            attackUnits += QueenCheckBonus * count_1s<Max15>(b);
 
         // Enemy rooks safe checks
         b = b1 & ei.attackedBy[Them][ROOK];
         if (b)
-            attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b);
+            attackUnits += RookCheckBonus * count_1s<Max15>(b);
 
         // Enemy bishops safe checks
         b = b2 & ei.attackedBy[Them][BISHOP];
         if (b)
-            attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b);
+            attackUnits += BishopCheckBonus * count_1s<Max15>(b);
 
         // Enemy knights safe checks
         b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
         if (b)
-            attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b);
+            attackUnits += KnightCheckBonus * count_1s<Max15>(b);
 
         // To index KingDangerTable[] attackUnits must be in [0, 99] range
         attackUnits = Min(99, Max(0, attackUnits));
@@ -865,6 +869,7 @@ namespace {
   template<Color Us, bool HasPopCnt>
   int evaluate_space(const Position& pos, EvalInfo& ei) {
 
+    const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
     // Find the safe squares for our pieces inside the area defined by
@@ -880,7 +885,7 @@ namespace {
     behind |= (Us == WHITE ? behind >>  8 : behind <<  8);
     behind |= (Us == WHITE ? behind >> 16 : behind << 16);
 
-    return count_1s_max_15<HasPopCnt>(safe) + count_1s_max_15<HasPopCnt>(behind & safe);
+    return count_1s<Max15>(safe) + count_1s<Max15>(behind & safe);
   }
 
 

src/misc.cpp

@@ -146,7 +146,7 @@ void dbg_print_mean(ofstream& logFile) {
 
 const string engine_name() {
 
-  const string cpu64(CpuHas64BitPath ? " 64bit" : "");
+  const string cpu64(CpuIs64Bit ? " 64bit" : "");
 
   if (!EngineVersion.empty())
       return AppName + " " + EngineVersion + cpu64;

src/pawns.cpp

@@ -147,6 +147,7 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
   Rank r;
   bool passed, isolated, doubled, opposed, chain, backward, candidate;
   Score value = SCORE_ZERO;
+  const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
   const Square* ptr = pos.piece_list_begin(Us, PAWN);
 
   // Initialize halfOpenFiles[]
@@ -206,7 +207,7 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
       // Test for candidate passed pawn
       candidate =   !(opposed | passed)
                  && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
-                 &&  count_1s_max_15(b) >= count_1s_max_15(attack_span_mask(Us, s) & theirPawns);
+                 &&  count_1s<Max15>(b) >= count_1s<Max15>(attack_span_mask(Us, s) & theirPawns);
 
       // In order to prevent doubled passed pawns from receiving a too big
       // bonus, only the frontmost passed pawn on each file is considered as

src/position.cpp

@@ -1917,7 +1917,7 @@ bool Position::is_ok(int* failedStep) const {
 
   // Is there more than 2 checkers?
   if (failedStep) (*failedStep)++;
-  if (debugCheckerCount && count_1s(st->checkersBB) > 2)
+  if (debugCheckerCount && count_1s<CNT32>(st->checkersBB) > 2)
       return false;
 
   // Bitboards OK?
@@ -1986,7 +1986,7 @@ bool Position::is_ok(int* failedStep) const {
   if (debugPieceCounts)
       for (Color c = WHITE; c <= BLACK; c++)
           for (PieceType pt = PAWN; pt <= KING; pt++)
-              if (pieceCount[c][pt] != count_1s(pieces(pt, c)))
+              if (pieceCount[c][pt] != count_1s<CNT32>(pieces(pt, c)))
                   return false;
 
   if (failedStep) (*failedStep)++;