From 92fc41226f784b251f41eab7e75c13075e980a54 Mon Sep 17 00:00:00 2001 From: Scott Gasch Date: Fri, 4 Sep 2026 16:46:27 -0700 Subject: Land bitboard move generation (Part A+B) and movesup.c bitboard queries; default on Implements the full board_representation/MOVEGEN_MIGRATION.md scope: bitboard-backed generators for all six not-in-check piece types plus the JumpTable-avoiding whole-node dispatch fork (_GenerateAllMovesBB), the in-check escape path (king flight + block/capture), and movesup.c's ExposesCheck/FasterExposesCheck/ExposesCheckEp/IsAttacked/ InCheck bitboard equivalents. Nine toggles total (GENERATE_{KNIGHT,KING,ROOK,BISHOP,QUEEN,PAWN}_BITBOARD, GENERATE_ESCAPES_{KING,BLOCK}_BITBOARD, EXPOSESCHECK_BITBOARD, ISATTACKED_BITBOARD), all now on by default in GNUmakefile -- DISABLE_BITBOARD_MOVEGEN=1 opts back into the mailbox path, which remains fully present and compiled either way. Correctness verified via perft (Kiwipete, Position 4), the move-set comparison harness across 20,000 random positions, all nine toggles combined cleanly (15/15 runs, after fixing a GenerateRandomLegalPosition en-passant-sentinel bug in the test harness), and sd10 on all three curated suites showing zero solve-count regression vs head_reference (the ecm_hard_quick delta traced to unrelated intervening commits). Speed: most individual generators land near parity by design (mailbox's per-square walk was already close to O(destination count)); the real, consistent wins are the dispatch-layer fork (up to 23% in dense positions) and IsAttackedBB (0.73x-0.93x of mailbox). Co-Authored-By: Claude Sonnet 5 Claude-Session: https://claude.ai/code/session_01AbHkVrm5KUyzLwWd3GHmo6 --- src/testsup.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) (limited to 'src/testsup.c') diff --git a/src/testsup.c b/src/testsup.c index 3ed50e3..d1b102d 100644 --- a/src/testsup.c +++ b/src/testsup.c @@ -87,7 +87,25 @@ GenerateRandomLegalPosition(POSITION *pos) { pos->cNonPawns[WHITE][u] = pos->cNonPawns[BLACK][u] = ILLEGAL_COOR; } - + + // memset above zeroes cEpSquare to 0x00 (A8), a real on-board + // square, not the "no en passant" sentinel -- every random + // position generated by this function had a bogus "en passant + // available on a8" flag set regardless of whether that made + // any sense. Both the mailbox and bitboard pawn generators + // trust this field and will act on it (mailbox: any pawn whose + // normal diagonal-capture target happens to coincide with a8; + // bitboard: proactively, once per side per node, since + // _GenerateAllPawnMovesBB/_SaveMeAllPawnMovesBB gate their + // en-passant block on IS_ON_BOARD(cEpSquare) directly) -- + // constructing a garbage "en passant capture" move whenever a + // pawn of the right color happens to sit on b7 by pure chance, + // which corrupts position state and was traced back to an + // intermittent TestSearch segfault (board_representation/ + // MOVEGEN_MIGRATION.md section 6b). + pos->cEpSquare = ILLEGAL_COOR; + + // // Place both kings legally // -- cgit v1.3