Small cleanups (march 2021)

With help of @BM123499, @mstembera, @gvreuls, @noobpwnftw and @Fanael
Thanks!

Closes #3405

No functional change

Author: snicolet

AUTHORS

@@ -1,4 +1,4 @@
-# List of authors for Stockfish, as of August 4, 2020
+# List of authors for Stockfish, as of March 24, 2021
 
 # Founders of the Stockfish project and fishtest infrastructure
 Tord Romstad (romstad)

src/bitbase.cpp

@@ -150,8 +150,8 @@ namespace {
     Bitboard b = attacks_bb<KING>(ksq[stm]);
 
     while (b)
-        r |= stm == WHITE ? db[index(BLACK, ksq[BLACK] , pop_lsb(b), psq)]
-                          : db[index(WHITE, pop_lsb(b),  ksq[WHITE], psq)];
+        r |= stm == WHITE ? db[index(BLACK, ksq[BLACK], pop_lsb(b), psq)]
+                          : db[index(WHITE, pop_lsb(b), ksq[WHITE], psq)];
 
     if (stm == WHITE)
     {

src/evaluate.cpp

@@ -54,7 +54,6 @@
 
 
 using namespace std;
-using namespace Stockfish::Eval::NNUE;
 
 namespace Stockfish {
 
@@ -396,7 +395,8 @@ namespace {
 
     attackedBy[Us][Pt] = 0;
 
-    while (b1) {
+    while (b1)
+    {
         Square s = pop_lsb(b1);
 
         // Find attacked squares, including x-ray attacks for bishops and rooks
@@ -1038,46 +1038,51 @@ namespace {
     return v;
   }
 
-  // specifically correct for cornered bishops to fix FRC with NNUE.
+
+  /// Fisher Random Chess: correction for cornered bishops, to fix chess960 play with NNUE
+
   Value fix_FRC(const Position& pos) {
 
-    Value bAdjust = Value(0);
+    constexpr Bitboard Corners =  1ULL << SQ_A1 | 1ULL << SQ_H1 | 1ULL << SQ_A8 | 1ULL << SQ_H8;
 
-    constexpr Value p1=Value(209), p2=Value(136), p3=Value(148);
+    if (!(pos.pieces(BISHOP) & Corners))
+        return VALUE_ZERO;
 
-    Color Us = pos.side_to_move();
-    if (   (pos.pieces(Us, BISHOP) & relative_square(Us, SQ_A1))
-        && (pos.pieces(Us, PAWN) & relative_square(Us, SQ_B2)))
-    {
-        bAdjust      -= !pos.empty(relative_square(Us,SQ_B3))                            ? p1
-                       : pos.piece_on(relative_square(Us,SQ_C3)) == make_piece(Us, PAWN) ? p2
-                                                                                         : p3;
-    }
-    if (   (pos.pieces(Us, BISHOP) & relative_square(Us, SQ_H1))
-        && (pos.pieces(Us, PAWN) & relative_square(Us, SQ_G2)))
-    {
-        bAdjust      -= !pos.empty(relative_square(Us,SQ_G3))                            ? p1
-                       : pos.piece_on(relative_square(Us,SQ_F3)) == make_piece(Us, PAWN) ? p2
-                                                                                         : p3;
-    }
-    if (   (pos.pieces(~Us, BISHOP) & relative_square(Us, SQ_A8))
-        && (pos.pieces(~Us, PAWN) & relative_square(Us, SQ_B7)))
-    {
-        bAdjust      += !pos.empty(relative_square(Us,SQ_B6))                             ? p1
-                       : pos.piece_on(relative_square(Us,SQ_C6)) == make_piece(~Us, PAWN) ? p2
-                                                                                          : p3;
-    }
-    if (   (pos.pieces(~Us, BISHOP) & relative_square(Us, SQ_H8))
-        && (pos.pieces(~Us, PAWN) & relative_square(Us, SQ_G7)))
-    {
-        bAdjust      += !pos.empty(relative_square(Us,SQ_G6))                             ? p1
-                       : pos.piece_on(relative_square(Us,SQ_F6)) == make_piece(~Us, PAWN) ? p2
-                                                                                          : p3;
-    }
-    return bAdjust;
+    constexpr int penalty1 = -209;
+    constexpr int penalty2 = -136;
+    constexpr int penalty3 = -148;
+
+    int correction = 0;
+
+    if (   pos.piece_on(SQ_A1) == W_BISHOP
+        && pos.piece_on(SQ_B2) == W_PAWN)
+        correction += !pos.empty(SQ_B3)              ? penalty1
+                     : pos.piece_on(SQ_C3) == W_PAWN ? penalty2
+                                                     : penalty3;
+
+    if (   pos.piece_on(SQ_H1) == W_BISHOP
+        && pos.piece_on(SQ_G2) == W_PAWN)
+        correction += !pos.empty(SQ_G3)              ? penalty1
+                     : pos.piece_on(SQ_F3) == W_PAWN ? penalty2
+                                                     : penalty3;
+
+    if (   pos.piece_on(SQ_A8) == B_BISHOP
+        && pos.piece_on(SQ_B7) == B_PAWN)
+        correction += !pos.empty(SQ_B6)              ? -penalty1
+                     : pos.piece_on(SQ_C6) == B_PAWN ? -penalty2
+                                                     : -penalty3;
+
+    if (   pos.piece_on(SQ_H8) == B_BISHOP
+        && pos.piece_on(SQ_G7) == B_PAWN)
+        correction += !pos.empty(SQ_G6)              ? -penalty1
+                     : pos.piece_on(SQ_F6) == B_PAWN ? -penalty2
+                                                     : -penalty3;
+
+    return pos.side_to_move() == WHITE ?  Value(correction)
+                                       : -Value(correction);
   }
 
-} // namespace
+} // namespace Eval
 
 
 /// evaluate() is the evaluator for the outer world. It returns a static
@@ -1092,14 +1097,19 @@ Value Eval::evaluate(const Position& pos) {
   else
   {
       // Scale and shift NNUE for compatibility with search and classical evaluation
-      auto  adjusted_NNUE = [&](){
-         int mat = pos.non_pawn_material() + 2 * PawnValueMg * pos.count<PAWN>();
-         Value nnueValue = NNUE::evaluate(pos) * (641 + mat / 32 - 4 * pos.rule50_count()) / 1024 + Tempo;
+      auto  adjusted_NNUE = [&]()
+      {
+         int material = pos.non_pawn_material() + 2 * PawnValueMg * pos.count<PAWN>();
+         int scale =  641
+                    + material / 32
+                    - 4 * pos.rule50_count();
+
+         Value nnue = NNUE::evaluate(pos) * scale / 1024 + Tempo;
 
          if (pos.is_chess960())
-            nnueValue += fix_FRC(pos);
+             nnue += fix_FRC(pos);
 
-         return nnueValue;
+         return nnue;
       };
 
       // If there is PSQ imbalance use classical eval, with small probability if it is small

src/material.cpp

@@ -74,7 +74,7 @@ namespace {
 
   bool is_KBPsK(const Position& pos, Color us) {
     return   pos.non_pawn_material(us) == BishopValueMg
-          && pos.count<PAWN  >(us) >= 1;
+          && pos.count<PAWN>(us) >= 1;
   }
 
   bool is_KQKRPs(const Position& pos, Color us) {

src/misc.cpp

@@ -362,8 +362,12 @@ void std_aligned_free(void* ptr) {
 /// aligned_large_pages_alloc() will return suitably aligned memory, if possible using large pages.
 
 #if defined(_WIN32)
-#if defined(_WIN64)
-static void* aligned_large_pages_alloc_win(size_t allocSize) {
+
+static void* aligned_large_pages_alloc_windows(size_t allocSize) {
+
+  #if !defined(_WIN64)
+    return nullptr;
+  #else
 
   HANDLE hProcessToken { };
   LUID luid { };
@@ -406,21 +410,18 @@ static void* aligned_large_pages_alloc_win(size_t allocSize) {
   CloseHandle(hProcessToken);
 
   return mem;
+
+  #endif
 }
-#endif
 
 void* aligned_large_pages_alloc(size_t allocSize) {
 
-#if defined(_WIN64)
   // Try to allocate large pages
-  void* mem = aligned_large_pages_alloc_win(allocSize);
+  void* mem = aligned_large_pages_alloc_windows(allocSize);
 
   // Fall back to regular, page aligned, allocation if necessary
   if (!mem)
       mem = VirtualAlloc(NULL, allocSize, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
-#else
-  void* mem = VirtualAlloc(NULL, allocSize, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
-#endif
 
   return mem;
 }
@@ -456,8 +457,9 @@ void aligned_large_pages_free(void* mem) {
   if (mem && !VirtualFree(mem, 0, MEM_RELEASE))
   {
       DWORD err = GetLastError();
-      std::cerr << "Failed to free transposition table. Error code: 0x" <<
-          std::hex << err << std::dec << std::endl;
+      std::cerr << "Failed to free large page memory. Error code: 0x"
+                << std::hex << err
+                << std::dec << std::endl;
       exit(EXIT_FAILURE);
   }
 }

src/movegen.cpp

@@ -182,7 +182,8 @@ namespace {
 
     Bitboard bb = piecesToMove & pos.pieces(Pt);
 
-    while (bb) {
+    while (bb)
+    {
         Square from = pop_lsb(bb);
 
         Bitboard b = attacks_bb<Pt>(from, pos.pieces()) & target;

src/nnue/features/half_kp.cpp

@@ -40,7 +40,8 @@ namespace Stockfish::Eval::NNUE::Features {
 
     Square ksq = orient(perspective, pos.square<KING>(perspective));
     Bitboard bb = pos.pieces() & ~pos.pieces(KING);
-    while (bb) {
+    while (bb)
+    {
       Square s = pop_lsb(bb);
       active->push_back(make_index(perspective, s, pos.piece_on(s), ksq));
     }

src/nnue/layers/affine_transform.h

@@ -96,7 +96,7 @@ namespace Stockfish::Eval::NNUE::Layers {
                           IndexType idx = k / 2 * kOutputDimensions * 4 + k % 2;
                           sum[w[idx] < 0] += w[idx];
                       }
-                      for (int sign : {-1, 1})
+                      for (int sign : { -1, 1 })
                           while (sign * sum[sign == -1] > 258)
                           {
                               int maxK = 0, maxW = 0;
@@ -234,9 +234,9 @@ namespace Stockfish::Eval::NNUE::Layers {
         __m128i product1 = _mm_maddubs_epi16(a1, b1);
         __m128i product2 = _mm_maddubs_epi16(a2, b2);
         __m128i product3 = _mm_maddubs_epi16(a3, b3);
-        product0 = _mm_adds_epi16(product0, product1);
-        product2 = _mm_adds_epi16(product2, product3);
-        product0 = _mm_adds_epi16(product0, product2);
+        product0 = _mm_add_epi16(product0, product1);
+        product2 = _mm_add_epi16(product2, product3);
+        product0 = _mm_add_epi16(product0, product2);
         product0 = _mm_madd_epi16(product0, kOnes128);
         acc = _mm_add_epi32(acc, product0);
       };

src/pawns.cpp

@@ -109,7 +109,8 @@ namespace {
     e->blockedCount += popcount(shift<Up>(ourPawns) & (theirPawns | doubleAttackThem));
 
     // Loop through all pawns of the current color and score each pawn
-    while (b) {
+    while (b)
+    {
         s = pop_lsb(b);
 
         assert(pos.piece_on(s) == make_piece(Us, PAWN));

src/search.cpp

@@ -612,12 +612,12 @@ namespace {
 
     // Step 1. Initialize node
     Thread* thisThread = pos.this_thread();
-    ss->inCheck = pos.checkers();
-    priorCapture = pos.captured_piece();
-    Color us = pos.side_to_move();
-    moveCount = captureCount = quietCount = ss->moveCount = 0;
-    bestValue = -VALUE_INFINITE;
-    maxValue = VALUE_INFINITE;
+    ss->inCheck        = pos.checkers();
+    priorCapture       = pos.captured_piece();
+    Color us           = pos.side_to_move();
+    moveCount          = captureCount = quietCount = ss->moveCount = 0;
+    bestValue          = -VALUE_INFINITE;
+    maxValue           = VALUE_INFINITE;
     ss->distanceFromPv = (PvNode ? 0 : ss->distanceFromPv);
 
     // Check for the available remaining time
@@ -917,6 +917,7 @@ namespace {
             return probCutBeta;
 
         assert(probCutBeta < VALUE_INFINITE);
+
         MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory);
         int probCutCount = 0;
         bool ttPv = ss->ttPv;
@@ -1121,6 +1122,7 @@ namespace {
       {
           Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2;
           Depth singularDepth = (depth - 1 + 3 * formerPv) / 2;
+
           ss->excludedMove = move;
           value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode);
           ss->excludedMove = MOVE_NONE;
@@ -1205,15 +1207,19 @@ namespace {
 
           // Decrease reduction if position is or has been on the PV
           // and node is not likely to fail low. (~10 Elo)
-          if (ss->ttPv && !likelyFailLow)
+          if (   ss->ttPv
+              && !likelyFailLow)
               r -= 2;
 
           // Increase reduction at root and non-PV nodes when the best move does not change frequently
-          if ((rootNode || !PvNode) && thisThread->rootDepth > 10 && thisThread->bestMoveChanges <= 2)
+          if (   (rootNode || !PvNode)
+              && thisThread->rootDepth > 10
+              && thisThread->bestMoveChanges <= 2)
               r++;
 
           // More reductions for late moves if position was not in previous PV
-          if (moveCountPruning && !formerPv)
+          if (   moveCountPruning
+              && !formerPv)
               r++;
 
           // Decrease reduction if opponent's move count is high (~5 Elo)
@@ -1226,7 +1232,7 @@ namespace {
 
           if (captureOrPromotion)
           {
-              // Unless giving check, this capture is likely bad
+              // Increase reduction for non-checking captures likely to be bad
               if (   !givesCheck
                   && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 210 * depth <= alpha)
                   r++;
@@ -1246,7 +1252,7 @@ namespace {
 
               // Decrease reduction for moves that escape a capture. Filter out
               // castling moves, because they are coded as "king captures rook" and
-              // hence break make_move(). (~2 Elo)
+              // hence break reverse_move() (~2 Elo)
               else if (    type_of(move) == NORMAL
                        && !pos.see_ge(reverse_move(move)))
                   r -= 2 + ss->ttPv - (type_of(movedPiece) == PAWN);
@@ -1408,8 +1414,9 @@ namespace {
     assert(moveCount || !ss->inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
 
     if (!moveCount)
-        bestValue = excludedMove ? alpha
-                   :     ss->inCheck ? mated_in(ss->ply) : VALUE_DRAW;
+        bestValue = excludedMove ? alpha :
+                    ss->inCheck  ? mated_in(ss->ply)
+                                 : VALUE_DRAW;
 
     // If there is a move which produces search value greater than alpha we update stats of searched moves
     else if (bestMove)

src/syzygy/tbprobe.cpp

@@ -192,7 +192,8 @@ class TBFile : public std::ifstream {
         std::stringstream ss(Paths);
         std::string path;
 
-        while (std::getline(ss, path, SepChar)) {
+        while (std::getline(ss, path, SepChar))
+        {
             fname = path + "/" + f;
             std::ifstream::open(fname);
             if (is_open())
@@ -567,7 +568,8 @@ int decompress_pairs(PairsData* d, uint64_t idx) {
     int buf64Size = 64;
     Sym sym;
 
-    while (true) {
+    while (true)
+    {
         int len = 0; // This is the symbol length - d->min_sym_len
 
         // Now get the symbol length. For any symbol s64 of length l right-padded
@@ -605,8 +607,8 @@ int decompress_pairs(PairsData* d, uint64_t idx) {
     // We binary-search for our value recursively expanding into the left and
     // right child symbols until we reach a leaf node where symlen[sym] + 1 == 1
     // that will store the value we need.
-    while (d->symlen[sym]) {
-
+    while (d->symlen[sym])
+    {
         Sym left = d->btree[sym].get<LR::Left>();
 
         // If a symbol contains 36 sub-symbols (d->symlen[sym] + 1 = 36) and

src/thread.cpp

@@ -128,14 +128,16 @@ void Thread::idle_loop() {
 
 void ThreadPool::set(size_t requested) {
 
-  if (size() > 0) { // destroy any existing thread(s)
+  if (size() > 0)   // destroy any existing thread(s)
+  {
       main()->wait_for_search_finished();
 
       while (size() > 0)
           delete back(), pop_back();
   }
 
-  if (requested > 0) { // create new thread(s)
+  if (requested > 0)   // create new thread(s)
+  {
       push_back(new MainThread(0));
 
       while (size() < requested)