From: mstembera Date: Tue, 6 Jun 2017 17:20:43 +0000 (-0700) Subject: Reordering magic data X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=659990b43ff1a089be9878561048fa4c60ba2705 Reordering magic data Gather all magic relevant data into a struct. This changes memory layout putting everything necessary for processing a single square in the same memory location thus speeding up access. Original patch by @snicolet No functional change. Closes #1127 Closes #1128 --- diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 1f6dab9d..99070ef2 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -26,15 +26,8 @@ uint8_t PopCnt16[1 << 16]; int SquareDistance[SQUARE_NB][SQUARE_NB]; -Bitboard RookMasks [SQUARE_NB]; -Bitboard RookMagics [SQUARE_NB]; -Bitboard* RookAttacks[SQUARE_NB]; -unsigned RookShifts [SQUARE_NB]; - -Bitboard BishopMasks [SQUARE_NB]; -Bitboard BishopMagics [SQUARE_NB]; -Bitboard* BishopAttacks[SQUARE_NB]; -unsigned BishopShifts [SQUARE_NB]; +Magic RookMagics[SQUARE_NB]; +Magic BishopMagics[SQUARE_NB]; Bitboard SquareBB[SQUARE_NB]; Bitboard FileBB[FILE_NB]; @@ -63,8 +56,7 @@ namespace { typedef unsigned (Fn)(Square, Bitboard); - void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], unsigned shifts[], Square deltas[], Fn index); + void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index); // bsf_index() returns the index into BSFTable[] to look up the bitscan. Uses // Matt Taylor's folding for 32 bit case, extended to 64 bit by Kim Walisch. @@ -212,8 +204,8 @@ void Bitboards::init() { Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST }; Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; - init_magics(RookTable, RookAttacks, RookMagics, RookMasks, RookShifts, RookDeltas, magic_index); - init_magics(BishopTable, BishopAttacks, BishopMagics, BishopMasks, BishopShifts, BishopDeltas, magic_index); + init_magics(RookTable, RookMagics, RookDeltas, magic_index); + init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index); for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) { @@ -259,8 +251,7 @@ namespace { // chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we // use the so called "fancy" approach. - void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) { + void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index) { int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020 }, { 728, 10316, 55013, 32803, 12281, 15100, 16645, 255 } }; @@ -269,7 +260,7 @@ namespace { int age[4096] = {0}, current = 0, i, size; // attacks[s] is a pointer to the beginning of the attacks table for square 's' - attacks[SQ_A1] = table; + magics[SQ_A1].attacks = table; for (Square s = SQ_A1; s <= SQ_H8; ++s) { @@ -281,8 +272,8 @@ namespace { // all the attacks for each possible subset of the mask and so is 2 power // the number of 1s of the mask. Hence we deduce the size of the shift to // apply to the 64 or 32 bits word to get the index. - masks[s] = sliding_attack(deltas, s, 0) & ~edges; - shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]); + magics[s].mask = sliding_attack(deltas, s, 0) & ~edges; + magics[s].shift = (Is64Bit ? 64 : 32) - popcount(magics[s].mask); // Use Carry-Rippler trick to enumerate all subsets of masks[s] and // store the corresponding sliding attack bitboard in reference[]. @@ -292,16 +283,16 @@ namespace { reference[size] = sliding_attack(deltas, s, b); if (HasPext) - attacks[s][pext(b, masks[s])] = reference[size]; + magics[s].attacks[pext(b, magics[s].mask)] = reference[size]; size++; - b = (b - masks[s]) & masks[s]; + b = (b - magics[s].mask) & magics[s].mask; } while (b); // Set the offset for the table of the next square. We have individual // table sizes for each square with "Fancy Magic Bitboards". if (s < SQ_H8) - attacks[s + 1] = attacks[s] + size; + magics[s + 1].attacks = magics[s].attacks + size; if (HasPext) continue; @@ -312,8 +303,8 @@ namespace { // until we find the one that passes the verification test. do { do - magics[s] = rng.sparse_rand(); - while (popcount((magics[s] * masks[s]) >> 56) < 6); + magics[s].magic = rng.sparse_rand(); + while (popcount((magics[s].magic * magics[s].mask) >> 56) < 6); // A good magic must map every possible occupancy to an index that // looks up the correct sliding attack in the attacks[s] database. @@ -326,9 +317,9 @@ namespace { if (age[idx] < current) { age[idx] = current; - attacks[s][idx] = reference[i]; + magics[s].attacks[idx] = reference[i]; } - else if (attacks[s][idx] != reference[i]) + else if (magics[s].attacks[idx] != reference[i]) break; } } while (i < size); diff --git a/src/bitboard.h b/src/bitboard.h index c957a40f..3ea92bdf 100644 --- a/src/bitboard.h +++ b/src/bitboard.h @@ -209,41 +209,47 @@ template<> inline int distance(Square x, Square y) { return distance(file_ template<> inline int distance(Square x, Square y) { return distance(rank_of(x), rank_of(y)); } +/// Magic holds all magic relevant data for a single square +struct Magic { + + Bitboard mask; + Bitboard magic; + Bitboard* attacks; + unsigned shift; +}; + /// attacks_bb() returns a bitboard representing all the squares attacked by a /// piece of type Pt (bishop or rook) placed on 's'. The helper magic_index() /// looks up the index using the 'magic bitboards' approach. template inline unsigned magic_index(Square s, Bitboard occupied) { - extern Bitboard RookMasks[SQUARE_NB]; - extern Bitboard RookMagics[SQUARE_NB]; - extern unsigned RookShifts[SQUARE_NB]; - extern Bitboard BishopMasks[SQUARE_NB]; - extern Bitboard BishopMagics[SQUARE_NB]; - extern unsigned BishopShifts[SQUARE_NB]; + extern Magic RookMagics[SQUARE_NB]; + extern Magic BishopMagics[SQUARE_NB]; - Bitboard* const Masks = Pt == ROOK ? RookMasks : BishopMasks; - Bitboard* const Magics = Pt == ROOK ? RookMagics : BishopMagics; - unsigned* const Shifts = Pt == ROOK ? RookShifts : BishopShifts; + const Magic* Magics = Pt == ROOK ? RookMagics : BishopMagics; + Bitboard mask = Magics[s].mask; + Bitboard magic = Magics[s].magic; + unsigned shift = Magics[s].shift; if (HasPext) - return unsigned(pext(occupied, Masks[s])); + return unsigned(pext(occupied, mask)); if (Is64Bit) - return unsigned(((occupied & Masks[s]) * Magics[s]) >> Shifts[s]); + return unsigned(((occupied & mask) * magic) >> shift); - unsigned lo = unsigned(occupied) & unsigned(Masks[s]); - unsigned hi = unsigned(occupied >> 32) & unsigned(Masks[s] >> 32); - return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s]; + unsigned lo = unsigned(occupied) & unsigned(mask); + unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32); + return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift; } template inline Bitboard attacks_bb(Square s, Bitboard occupied) { - extern Bitboard* RookAttacks[SQUARE_NB]; - extern Bitboard* BishopAttacks[SQUARE_NB]; + extern Magic RookMagics[SQUARE_NB]; + extern Magic BishopMagics[SQUARE_NB]; - return (Pt == ROOK ? RookAttacks : BishopAttacks)[s][magic_index(s, occupied)]; + return (Pt == ROOK ? RookMagics : BishopMagics)[s].attacks[magic_index(s, occupied)]; } inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {