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chess.h: add POSITION::bbOccupied (full-board occupancy, both colors,
every piece including kings), maintained incrementally alongside
bbPieces/bbPawns rather than rebuilt on demand -- resolves the open
question in EVAL.md section 0 about whether this is worth doing given
both generate.c and the planned eval.c mobility rewrite need it.
move.c: SlidePiece/SlidePawn/LiftPiece/PlacePiece and their
WithoutSigs variants now maintain bbOccupied at the same choke points
that already maintain bbPieces/bbPawns -- unconditionally, since
occupancy doesn't care about piece type or color. Kings only ever
move through SlidePiece/SlidePieceWithoutSigs (never Lift/Place), so
no separate king-specific update site was needed.
fen.c: populate bbOccupied when parsing a FEN.
board.c: VerifyPositionConsistency cross-checks pos->bbOccupied
against a from-scratch rebuild, same pattern already used for
bbPieces/bbPawns.
generate.c/movesup.c/see.c: replace call sites that rebuilt full
occupancy via _BuildFullOccupiedBB/_BuildOccupiedBB with direct reads
of pos->bbOccupied; delete see.c's _BuildOccupiedBB, which was a
byte-for-byte duplicate of generate.c's _BuildFullOccupiedBB (kept
only as the from-scratch ground truth for the new consistency check
and testgenerate.c's benchmark harness).
testsup.c: GenerateRandomLegalPosition builds POSITIONs by poking
rgSquare/bbPieces/bbPawns directly, bypassing both move.c and fen.c --
a third construction path the above missed. It never set bbOccupied,
so the new VerifyPositionConsistency check failed on every generated
position, and since generation retries until a position verifies, the
self-test suite spun forever (100% CPU, no progress) instead of
crashing outright. Fixed by setting bbOccupied at all four placement
sites (both kings, pawn, non-pawn piece). Full self-test suite and
precommit_check.sh verified clean afterward.
board_representation/EVAL.md: record the bbOccupied decision and
rationale, resolving section 0's open question.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01P6g6iF6mD1Hau6nCZCzwYj
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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 <[email protected]>
Claude-Session: https://claude.ai/code/session_01AbHkVrm5KUyzLwWd3GHmo6
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Clean gmake GENETIC=1 PERF_COUNTERS=1 MP=1 SIXTYFOUR=1 build had 100
warnings; DEBUG=1 and TEST=1 builds had more once actually exercised.
- OFFSET_OF/CONTAINING_STRUCT (chess.h) and PTR_TO_ALLOC_HASH (unix.c)
truncated pointers through 32-bit ULONG before use in offset/hash
arithmetic on this 64-bit build -- routed through size_t instead.
- Diagnostic int<->void* round-trips (command.c, root.c, split.c,
sig.c, data.c, unix.c, util.c) widened/narrowed via size_t to avoid
implicit truncation.
- ABS_DIFF on unsigned COOR now casts to int before abs().
- Dropped -fexpensive-optimizations (GCC-only, clang silently ignores
it) from GNUmakefile.
- Removed genuinely dead variables (book.c, gamelist.c, split.c,
testgenerate.c, testhash.c).
- Guarded DEBUG/PERF_COUNTERS/_X86_-only variables and the
_CMEvidenceBucket helper under the #ifdef that actually reads them,
since ASSERT/EVAL_TERM/KEEP_TRACK_OF_FIRST_MOVE_FHs compile away
outside those builds.
- Added missing prototypes for SlidePawn, SlidePawnWithoutSigs,
SlidePieceWithoutSigs (move.c), previously undeclared in chess.h.
- Removed dead _SystemIsRoot (unix.c).
Verified via precommit_check.sh: TEST=1 self-test suite passes,
DEBUG=1 smoke test (10 random ECM positions, sd 4) passes with no
crashes/assertions, release build restored -- all three profiles now
build with zero warnings.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_014Cmv11sJZqVfanrPh6UnWE
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countermove promotion, retired hung-piece-escape and NumLeftoverMovesToSelect.
Full session was built on a "measure the pick, not the game" methodology:
aggregate solve counts on curated suites are too noisy to tune move-ordering
knobs against, so most decisions here came from per-move fail-high/alpha-raise
rates at much larger sample sizes (leftover FH% instrumentation, a zero-
selection-budget diagnostic that isolates a single best-of-remaining pick,
and evidence-bucket calibration), not solve-count deltas alone. See
CLAUDE.md's "Dynamic move ordering experiments" section for the reusable
methodology and generate.c's _ScoreAllMoves comment for the resulting
ordering hierarchy.
Changes:
- Added g_ContinuationHistory: same growth/decay math as the existing
g_HistoryCounters butterfly table, additionally keyed by the previous
move, so its magnitude is self-calibrated rather than a hand-picked
constant. Flat, sufficient response across a 256x scale sweep.
- Countermove-table matches now get a real GOOD_MOVE-tier promotion
(previously the table was write-only, tracked for stats but never read
for ordering), but only when the match's own accumulated
history+continuation evidence clears COUNTERMOVE_EVIDENCE_THRESHOLD
(10,000) -- a raw match with no track record was shown to perform
identically to an ordinary leftover (~0.6-0.85% FH), so promoting on
match alone would have repeated hung-piece-escape's mistake below.
- Retired hung-piece-escape's unconditional GOOD_MOVE-tier promotion.
Evidence-calibration showed the overwhelming majority of triggers (a
zero-evidence population 250-1000x larger than countermove's) performed
at the plain-leftover baseline -- the promotion was mostly free tier-
escape treatment for moves that hadn't earned it. Replaced with
FLEE_BONUS, a flat same-tier nudge inside SelectBestWithHistory (never
escapes GOOD_MOVE/leftover classification, unlike a generation-time
promotion) at the magnitude found to plateau a same-tier-nudge sweep.
- Retired NumLeftoverMovesToSelect (the depth-indexed budget on how many
leftover moves got a full selection scan before falling back to
unsorted order). search.c's main move loop now always fully selects --
the leftover pool was shown to contain real, findable signal a bailout
budget was discarding for a node-count savings that didn't hold up net-
net once measured by solve counts and fail-high rates rather than raw
node counts (noisy on small suites independent of this change).
- Collapsed leftover-move instrumentation from sorted/raw pairs down to a
single set now that "raw" (unsorted fallback) is structurally
impossible; kept the countermove evidence-bucket calibration counters
(ongoing check that COUNTERMOVE_EVIDENCE_THRESHOLD stays well-
calibrated); removed the contested-node A/B harness and hung-piece
evidence calibration now that the decisions they were built to inform
are made.
Net effect on the three curated suites (sd 10): solve counts wash (tied,
+1, -1 across ringers/confident/hard), leftover fail-high rate improved
consistently on all three (the intended, directly-measured target of this
work). Not yet validated beyond sd 10 -- an sn-based run or
eval_tune/match_play.py head-to-head gate is the natural next check before
leaning on this as a proven strength gain rather than a directionally-
sound, sd-10-clean change.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_014XePz6Sk4qQsTaP2jVJWJu
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type-mixing bug and add a quiet-refutation killer backfill.
Killer tiers now try both of this ply's own killers before either
ply-2-back one, matching Crafty's ordering. Two earlier attempts at
this same swap were reverted for regressing; this pass lands on top of
NumLeftoverMovesToSelect (more SelectBestWithHistory budget to reach
these lower-tier slots) and a real bug fix below, and beats interleaved
order head-to-head on solves, node count, and first-move beta cutoff
across the three curated suites.
The bug: mvNullmoveRefutations's empty-killer-slot backfill could only
ever contain a capturing move (TryNullmovePruning only wrote it inside
the capture-refutation branch), but IS_SAME_MOVE's mask includes the
pCaptured bits, so that backfilled value could never match a real
quiet candidate -- the backfill was silently dead code. Fixed by
recording genuinely quiet null-move refutations into a new, separate
mvNullmoveQuietRefutations array (kept separate so it can't clobber the
capture history mvNullmoveRefutations still needs for the
Botvinnik-Markoff same-piece-two-squares extension check) and
backfilling the regular killer table from that instead. The
check-evasion killer table intentionally does *not* get this backfill:
a null-move refutation can never legitimately be an escaping-check
move (null moves can't deliver check), so backfilling there risks
IS_SAME_MOVE cross-context false positives instead of the old
guaranteed-inert no-op.
Measured at sd10 across ecm_ringers/ecm_confident_quick/ecm_hard_quick
against head_reference (commit d11e973): 115/191 solves (vs. 116
baseline), 924.36M total nodes (vs. 933.23M), first-move beta cutoff
within 0.1-0.9 points of baseline on all three suites -- and clearly
better than the same fix under interleaved order (113/191 solves,
963.10M nodes), which loses to head_reference on every metric.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EortUUkDVpsfrbqshBJYJg
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EBF/beta-cutoff/counter-move stats, script.c FPE fix.
No LMR, no counter-move-driven move ordering (both explored separately,
kept out for now -- counter-move measured worse, ~655->647 solved on
ecm879 @ sn=4M with a leaner tree beforehand). Futility pruning restored.
Verified: 647/879 solved, EBF 4.609 @ sn=4M; 684/879 solved, EBF 3.995
@ 20s/move, 1cpu, 256m hash (typhoon_baseline.log).
The counter-move table is still written and its stats still tracked
(dynamic.c) for diagnostic purposes, but generate.c no longer reads it
for move ordering, so it has no effect on search behavior in this
commit.
lmr_testing/ holds the in-flight graded-LMR + counter-move code (not
applied here) with notes on what was already tried and measured, so a
future session can resume without re-deriving it.
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