| Age | Commit message (Collapse) | Author |
|---|
|
Add ASSERT(uWhite < 32)/ASSERT(uBlack < 32), the bound that actually
matters for g_SwapTable[14][32][32] -- the existing (& 0xFFFFFF00)
checks only caught garbage above bit 7 and would have passed silently
through the exact out-of-bounds indexing fixed in the previous commit,
had a similar bit-layout mistake been made again in the future.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01XxmVi2sTMwpPp4i6WYFjan
|
|
Recalibrate iKingSwingP90 against the bitboard-rewritten
CountKingSafetyDefects (~1.28B samples via new CALIBRATE_POSITIONAL/
CALIBRATE_BASE_MARGIN/CALIBRATE_MARGIN_SAFETY diagnostic build flags,
board_representation/EVAL.md section 9). Add LAZY_EVAL_MIN_MATERIAL:
measured the regular lazy exit's real swing exceeding its own assumed
margin 20.6% of the time in near-bare-king endgames (vs <=0.36%
elsewhere) -- skip lazy eval entirely below that material floor.
Double the stale search.c/searchsup.c CountKingSafetyDefects extension
thresholds as a stopgap pending their own recalibration.
Eval hot-path trimming (measured via EVAL_TIME, ~1759 -> ~1386 avg
cycles/eval on a representative middlegame position):
- Pull _GetFileStormDefects out of EstimatePositionalScore's hot path
(cost more than the "cheap cached lookup" it was assumed to be,
running on ~90% of all Eval() calls).
- Add pos->bbOccupiedSide[2], incrementally maintained alongside
bbOccupied, so _BuildFriendlySideBB is a field read instead of a
6-term OR.
- Switch CoorFromBitBoardRank8ToRank1/Rank1ToRank8 to the existing
static-inline FastFirstBit/FastLastBit (same bsf/bsr instruction,
no call/ret overhead).
- Defer EvalPasserRaces' uRacerDist/fDontCountMeOut past its
no-passer early return.
- Remove the mailbox-era "max mobility in a row" term from
_EvalBishop/_EvalRook (no bitboard-mobility equivalent need for it).
- Simplify _EvalBishopPairs and rook file-openness/passer bonuses to
flat DNA-tunable constants instead of distance/pawn-count-scaled
tables, rook file-openness now a branchless bitboard-indexed lookup.
- Remove pos->cPiece (write-only, no reader anywhere).
- Collapse WHITE/BLACK mirror-branches (castle-rights block,
rook-trapped-in-corner) to color-indexed constants.
- Close the PAWN_BIT..KING_BIT gap (bits 7-3 -> bits 4-0), removing
the bvPattern >>= 3 before its KING_COUNTER_BY_ATTACK_PATTERN
lookup. This also fixes a real bug introduced earlier this session
when _WhoControlsSquareFast was converted to read these constants
directly: g_SwapTable is only [32][32], but the old bit values
(up to 0xF8) indexed far out of bounds on any attacked square --
data.c's InitializeSwapTable was always built assuming the bits
0-4 range this change now actually produces.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01XxmVi2sTMwpPp4i6WYFjan
|
|
57502d6)
Flagged during the ATTACK_BITV/bvAttacks cleanup (5405191) but left
unfixed there deliberately, per direct instruction, since a real fix
changes eval scoring and deserves its own before/after check rather
than being buried in a mechanical rename commit.
The gate ("is this square safe to advance a helper pawn into, i.e.
not enemy-attacked or already friend-defended") used to read the old
combined bvAttacks word for both colors at the target square. This
function runs from _EvalPawns, the first piece type Eval() evaluates
each call -- no non-pawn piece (and, since commit 57502d6, not even
pawns themselves) has written any attack data yet at this point. That
word has therefore been unconditionally zero, and the gate
unconditionally true (silently disabled), since 57502d6 landed.
Fixed using pos->bbPawnAttacks -- the one piece-type bitboard that
actually is valid this early in Eval()'s sequence (populated at the
top of _EvalPawns, before this function runs). Narrower than whatever
the original gate covered (pawns only, not every piece type), but a
real, correct check instead of a fake one, and pawns are the dominant
real-world case for contesting a helper-pawn's advance square anyway.
Applied to both the right- and left-side helper searches (the initial
target-square check and the backward walk-and-search loop each need
their own copy, since the loop's own square changes every iteration).
Verified via precommit_check.sh, then all three curated suites at
sd10 (not just ringers, since this is a real eval-scoring change, not
a mechanical one): net +2/191 (113->115), concentrated in
ecm_hard_quick (18->22) with a small ecm_confident_quick give-back
(85->83) and ringers unchanged (10/11) -- the same "gains lopsided
toward hard_quick" shape this session's other real eval changes have
shown, consistent with a genuine (if modest) positional improvement
rather than suite-specific noise.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01XxmVi2sTMwpPp4i6WYFjan
|
|
Now that king (the last piece writing it) has converted to a bitboard
accumulator, nothing writes rgSquare[c|8].bvAttacks any more -- deletes
the whole mechanism rather than leaving a known-dead struct around:
- chess.h: ATTACK_BITV union gone. SQUARE collapses from a
union-with-ATTACK_BITV to a plain {pPiece, uIndex} struct (the #pragma
pack(1) that only existed for ATTACK_BITV's bitfield layout goes too).
UNSAFE_FOR_ROOK/UNSAFE_FOR_QUEEN and the whole-word MINOR_XRAY_BIT/
ROOK_XRAY_BIT/QUEEN_XRAY_BIT constants deleted -- confirmed unused
(only ever referenced in stale comments, not code) now that every
consumer reads bbXAttacks bitboards directly. PAWN_BIT/MINOR_BIT/
ROOK_BIT/QUEEN_BIT/KING_BIT stay: they're a separate, still-live
local bit-packing scheme _EvalKing/_WhoControlsSquareFast use to
build a per-square attack-pattern index into KING_COUNTER_BY_
ATTACK_PATTERN/g_SwapTable, unrelated to the retired storage struct.
- eval.c: _ClearAttackTables drops its entire macro-unrolled,
128-square clearing loop (CLEAR_A_SQ/CLEAR_A_RANK/CLEAR_SHORT_RANK,
all deleted) -- it only ever existed to zero the old per-square
struct; clearing the 7 bbXAttacks accumulators is the whole function
now. The transitional _IsSquareAttackedByX/_IsSquareXrayedByX helpers
(minor/rook/queen/king, 8 functions total) are deleted outright, not
just simplified -- their only remaining purpose was bridging to the
now-gone struct, and their DEBUG cross-checks were explicitly
migration-only scaffolding, not a permanent invariant. Call sites
(_WhoControlsSquareFast, _EvalKing's bvAttack/bvXray/bvDefend) read
the bbXAttacks bitboards directly instead. _WhoControlsSquareFast
simplifies to a flat OR of 8 bitboard membership tests per color,
down from raw struct reads plus 7 helper calls each.
Found and fixed one real, pre-existing bug while doing this (flagged
and confirmed with the user before touching it, kept as its own
documented change rather than silently folded into the mechanical
rename): _EvaluateCandidatePasser's helper-pawn-safety gate read
rgSquare[c1+8].bvAttacks[...].uWholeThing, but this function runs from
_EvalPawns -- the first piece type Eval() evaluates each call, before
any non-pawn piece (or, since commit 57502d6 retired pawns' own
bvAttacks write, even pawns) has written anything there. That word has
therefore been unconditionally zero, and the gate unconditionally true
(a silent no-op), since 57502d6 landed -- not something today's cleanup
introduced. Left exactly as dead/unconditional (deleted the
now-meaningless condition, kept the body it always ran anyway) rather
than fixed, since a real fix changes eval scoring and deserves its own
before/after check, documented inline for a future session.
Verification: precommit_check.sh (self-test + DEBUG smoke test) passes.
tests/ecm_ringers.ep_ at sd10 vs. the immediately preceding commit:
solve parity holds exactly (10/11 both), and final (depth-10) node
counts are byte-identical for all 11 positions -- the bar for a change
meant to be purely mechanical, unlike king's own conversion. One
harmless artifact noted: ECM.750 has a different depth-6 *intermediate*
best move (a shallow tie-break flip) that already resolves to the
identical PV and node count by depth 7 and holds through depth 10 --
not chased further since the actual (depth-10) result matches exactly
and search is deterministic at --cpus 1.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01XxmVi2sTMwpPp4i6WYFjan
|
|
asymmetry
_EvalKing was the last piece type contributing to the old bvAttacks/
ATTACK_BITV mechanism -- both write sites (the low-enemy-material
early-exit path and the main king-safety loop) replaced with a single
pos->bbKingAttacks[uColor] |= g_KingAttacksBB[c], plus a new
_IsSquareAttackedByKing transitional helper (DEBUG-cross-checked, no
x-ray companion needed since a king can't move through a blocker) for
_WhoControlsSquareFast and _EvalKing's own bvDefend to read.
Two real, intentional behavior changes land with this conversion,
both discussed and confirmed before coding rather than assumed:
1. The main king-safety loop's old per-square write used
KingSafetyDeltas (11 entries: the 8 real king-move squares plus -2/
+2, two squares away on the same rank, present only for that loop's
own file-distance bookkeeping) instead of the real 8-square king
move pattern -- a bug, confirmed by direct instruction, not a
design choice worth preserving. Fixed by writing the real
g_KingAttacksBB[c] pattern once, before the loop, instead of
whatever KingSafetyDeltas happened to visit per-square.
2. _EvalKing's own bvAttack computation (does the *enemy* king attack
a square near this king?) is now symmetric where it used to be an
accidental artifact of evaluation order: kings are evaluated
black-then-white, so the old mailbox code let white's computation
see black's already-written king bit while black's could never see
white's (white hadn't run yet). Rather than preserve or upgrade
that asymmetry now that both colors go through an explicit helper
either way, neither side sees the enemy king as a threat here,
matching the side that already couldn't -- by direct instruction.
This is narrow in practice (two kings can never be legally
adjacent, so it only ever fires at king-vs-king distance 2) but
real.
_WhoControlsSquareFast's own king contribution is unaffected by either
change and stays fully symmetric: it's only ever called after *both*
kings finish evaluating (the passed-pawn re-check and trapped-piece/
danger passes all run after Eval()'s king-eval block), so
pos->bbKingAttacks is always fully populated for both colors by the
time it runs -- confirmed by checking call-site ordering directly, not
assumed from bvAttack's own (different) situation.
CountKingSafetyDefects is untouched by this change (confirmed by
reading it again): it's pure CHECK_VECTOR geometry over piece
locations, computed before any bbXAttacks accumulator exists this
Eval() call, and reads none of them. Its correlation with _EvalKing's
score is therefore preserved by construction, not something requiring
separate re-tuning.
Verification: since this bundles three attributable behavior changes
(the bitboard rewrite itself, the KingSafetyDeltas bug fix, and the
dropped bvAttack asymmetry), used the ringers-suite-plus-bounded-delta
bar from bishop's conversion rather than expecting exact node-count
equality: precommit_check.sh (self-test + DEBUG smoke test, plus
several hand-built king-adjacency/king-proximity positions run
directly against a DEBUG binary to exercise the new cross-check) all
pass; whole-engine tests/ecm_ringers.ep_ at sd10 vs. the immediately
preceding commit holds exact solve parity (10/11 both), with
per-position node-count deltas (-50% to +76%) all attributable to the
three documented changes above, no unexplained outliers.
ATTACK_BITV/bvAttacks itself is intentionally left in place -- nothing
writes it any more (king was the last writer), but the struct deletion
and the resulting simplification of the transitional
_IsSquareAttackedByX/_IsSquareXrayedByX helpers (which collapse to
plain bitboard reads once nothing can ever populate the old structure)
is staged as a deliberate follow-up commit, not bundled here.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01XxmVi2sTMwpPp4i6WYFjan
|
|
rook/bishop mobility to credit squares beyond a battery partner
_EvalQueen's mobility ray-walk and QMobCaseTable switch replaced with
two passes of the same unified chain-walk technique rook/bishop use --
_RookAttacksBB for the orthogonal-direction pass, _BishopAttacksBB for
the diagonal-direction pass (MOVEGEN_MIGRATION.md/EVAL.md already
established a combined 8-ray table measures slower than reusing the
rook/bishop tables separately, per the stashed first bitboard-eval
attempt's _EvalQueenOccupancyBB PoC -- reused that structure instead of
rediscovering the regression). Continue-set per pass: friendly queen in
both, friendly rook only in the rook-direction pass, friendly bishop
only in the bishop-direction pass -- QMOB_FRIEND_ROOK/_BISHOP's old
fOrthogonalRay flag is entirely subsumed by which lookup a blocker
shows up in. Queen never x-rays through any enemy piece (unlike
rook/bishop), so each pass's continue-set has no enemy side. Adds
pos->bbQueenAttacks[2]/bbQueenXrayAttacks[2] and the corresponding
_IsSquareAttackedByQueen/_IsSquareXrayedByQueen transitional helpers
(DEBUG-cross-checked against an independent mailbox walk, same pattern
as the rook/minor helpers), with _WhoControlsSquareFast and _EvalKing's
bvAttack/bvXray/bvDefend/uQueenNearKing computations updated to read
them instead of the old per-square bvAttacks bits queen no longer
writes.
Also fixes a real, previously-unnoticed fidelity gap in the
already-committed rook and bishop conversions: the old mailbox walk
doesn't just x-ray past a friendly battery partner (or, for rook/
bishop specifically, an x-rayable enemy queen/king) for attack-bit
purposes -- it keeps walking and keeps crediting *mobility* for
whatever safe/empty squares and further captures lie beyond, however
many such blockers are stacked on one ray. The originally-committed
bitboard versions only ever computed mobility from the near side (up
to the first blocker via the magic lookup) and treated the chain
purely as an attack-bit population exercise. Caught by direct
comparison against the pre-conversion mailbox binary on battery
positions (rook: two same-color rooks on an open file, old code
credited 13 mobility to one rook via squares beyond its companion vs.
9 for the near-side-only bitboard version; bishop: two same-color
bishops on one diagonal, 12/8 old vs. 11/5 near-side-only). Fixed by
merging each piece's mobility and x-ray-population computation into a
single chain-walk that credits mobility at every layer, not just the
first -- queen's own conversion was written with this fix in from the
start and verified against the same kind of battery position (two
queens on a file, queen+rook, queen+bishop) before landing.
Verified via precommit_check.sh (self-test + DEBUG smoke test, several
hand-built multi-piece-battery positions run directly against a DEBUG
binary to exercise the new cross-checks) after each step.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01XxmVi2sTMwpPp4i6WYFjan
|
|
bishop
_EvalRook's mobility ray-walk and RMobCaseTable switch replaced with
_RookAttacksBB(c, pos->bbOccupied) plus bitboard masks, same technique
as knight/bishop. Adds pos->bbRookAttacks[2]/bbRookXrayAttacks[2],
first contributors alongside bbMinorAttacks/bbMinorXrayAttacks.
Connected-rook bonus and x-ray population derived from the attack
bitboard instead of a per-square dispatch.
Unlike bishop's single-hop x-ray simplification, rook's x-ray
population uses a bounded chain-following loop (recompute with the
newly-found blocker excluded, repeat until no new x-ray-worthy
terminal appears): checked frequency first (board_representation/
EVAL.md), and 14% of the curated-suite positions have a genuine
2+-deep rook/queen battery on some ray, far more common than bishop's
~1% -- a one-hop approximation here would be a real fidelity loss, not
a negligible one. The stashed first bitboard-eval attempt (git
stash@{1}) had already solved this correctly by walking blocker-to-
blocker via bit-scan; this reproduces the same unbounded behavior via
repeated magic-lookup recomputation, cheap because the loop only
iterates again when an actual chained battery exists.
Backported the same bounded-chain fix to bishop's x-ray population
(previously single-hop only) for consistency, now that it's known
cheap and mechanically identical -- bishop's own battery rate is much
lower (~1%) so this mostly just removes an intentional divergence
rather than fixing an active problem.
Also fixes two real correctness gaps this conversion would otherwise
have introduced silently (same failure mode as pawn's earlier
conversion, EVAL.md's progress log): rook no longer writes ROOK_BIT/
ROOK_XRAY_BIT into the old per-square bvAttacks structure, but
_WhoControlsSquareFast and queen's mobility unsafe-check both still
read those bits directly. Added _IsSquareAttackedByRook/
_IsSquareXrayedByRook (same transitional-helper, DEBUG-cross-checked
pattern as the minor-piece helpers) and updated both call sites.
Verified via precommit_check.sh (self-test + DEBUG smoke test) after
each step.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01XxmVi2sTMwpPp4i6WYFjan
|
|
_EvalBishop's mobility ray-walk (per-square g_iBDeltas delta-walk +
BMobCaseTable switch dispatch) replaced with _BishopAttacksBB(c,
pos->bbOccupied) -- generate.c's magic-bitboard slider lookup,
already used by move generation -- plus bitboard masks for the
mobility count, matching knight's reduction pattern:
enemy-non-pawn-terminal counts unconditionally, empty-or-enemy-pawn-
terminal counts unless pawn-unsafe (via bbPawnAttacks), and the one
case that isn't a pure occupancy mask -- a terminal friendly,
non-stationary pawn on this bishop's own color complex -- keeps its
credit via bbPc (already computed for the existing good/bad
transient-pawn scoring, untouched this change).
Adds POSITION::bbMinorAttacks contributions from bishop (direct
attack bits) and POSITION::bbMinorXrayAttacks (new field) for squares
seen through a friendly bishop/queen battery partner or an
x-rayable enemy rook/queen/king.
Deliberate behavior change from the old ray-walk, made for speed per
direct instruction: the old walk's fStop=FALSE for the x-ray cases
meant it kept going -- and kept counting mobility -- through however
many x-ray-worthy blockers were stacked consecutively on one ray
(e.g. x-raying an enemy rook, then continuing to x-ray *through* an
enemy king sitting right behind it too). The bitboard version only
extends one hop past the first x-ray-worthy blocker; it does not
re-check whether the newly-revealed terminal square is itself
x-ray-worthy and extend again. This was found and deliberately kept
(not fixed) after a DEBUG assert caught the exact case on
8/1R1B4/2B1r3/5k2/2P2P2/1p6/1Kb5/7n w - - during precommit's random-
sample smoke test -- judged an acceptable trade given how rare a ray
with >=2 consecutive x-ray-worthy pieces is.
Two new transitional helpers (_IsSquareAttackedByMinor's bishop
contribution, and new _IsSquareXrayedByMinor) carry bishop's combined
state to every remaining consumer (rook/queen mobility-safety checks,
king's danger computation, _WhoControlsSquareFast) -- both DEBUG-
asserted against an independent from-scratch mailbox ray-walk (using
the still-live rgSquare representation, not any shared code with the
production bitboard technique) implementing this same single-hop
rule, so a real regression fails loudly rather than drifting into a
wrong score.
Verified via precommit_check.sh and the full tests/ecm_ringers.ep_
suite at sd10 against the prior commit (7e3e6b6): same 10/11 solved
(same single miss, ECM.335, in both), node counts now legitimately
differ per position (expected given the semantic change) but stay in
a bounded, reasonable range (-17% to +20%), nothing resembling the
60%+ blowups a real bug produced earlier in this same session before
being caught, isolated, and traced to this exact x-ray-chain gap.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01P6g6iF6mD1Hau6nCZCzwYj
|
|
_EvalKnight's mobility loop (per-square g_iNDeltas delta-walk +
NMobCaseTable switch dispatch) replaced entirely with
g_KnightAttacksBB[c] (generate.c's precomputed table, already used by
move generation) plus two bitboard masks -- knights never x-ray or
have a battery partner, so the old four-case table collapses to
"enemy non-pawn: count unconditionally" and "empty-or-enemy-pawn:
count unless pawn-unsafe."
Adds POSITION::bbMinorAttacks[2] (chess.h), the first of the
bbMinorAttacks/bbRookAttacks/bbQueenAttacks accumulators from
board_representation/EVAL.md section 2 -- knight ORs its full attack
set in directly, no per-square bit-scan needed. Bishop is not
converted yet and still writes its own minor-bit contribution into
the old per-square rgSquare[c|8].bvAttacks structure.
Since knight stopped writing that old structure, every consumer that
needs "does any minor attack this square" (rook/queen's mobility-
safety check, king's danger computation, _WhoControlsSquareFast) now
goes through a new transitional helper, _IsSquareAttackedByMinor,
which ORs the new bitboard (knight) with the old bvAttacks bit
(bishop) in exactly one place rather than each call site hand-rolling
its own combination -- this collapses to a plain bbMinorAttacks read
once bishop converts too, and the helper goes away entirely.
_IsSquareAttackedByMinor is DEBUG-asserted against an independent
recomputation (g_KnightAttacksBB / _BishopAttacksBB, both already-
trusted primitives from move generation, unrelated to either the old
ray-walk's bit bookkeeping or the new accumulator) so a bug in either
mechanism fails loudly in any DEBUG build/smoke-test run rather than
silently drifting into a wrong score deep in search.
Verified via precommit_check.sh and a direct before/after node-count
comparison (sd10, r1bq1rk1/pp2bppp/2n1pn2/2pp4/3P4/2NBPN2/PP3PPP/
R1BQ1RK1 w - - 0 1): byte-identical, 3125335 nodes both builds.
This landed as a deliberately small, single-piece-type step after an
earlier attempt to convert knight+bishop+rook+queen+king in one
combined change produced a real bug (a byte-scale mismatch in xray
bit reconstruction) that was hard to isolate with five things changed
at once, and was reverted back to 6e86450 rather than debugged
further. Bishop, rook, queen, and _EvalKing's own conversion are
follow-up steps, each to be landed and verified the same way, one at
a time.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01P6g6iF6mD1Hau6nCZCzwYj
|
|
The old loop walked cNonPawns[color][1..N] (a flat, arbitrarily-
ordered list mixing knight/bishop/rook/queen), doing a mailbox lookup
plus a p&0x4/IS_KNIGHT branch per piece to decide which _Eval*
function to call, then stashing rooks/queens into cDefer/uDefer
arrays to evaluate in a later pass -- a hard-to-predict branch per
piece on top of a mailbox read the callee already redoes for its own
ASSERT.
pos->bbPieces[color][PIECE_TYPE] already exists (incrementally
maintained by move.c) and was simply unused by Eval() until now.
Replaced the whole dispatch with a direct per-type bitboard walk:
knights, then bishops, for side-to-move, then the same for the other
side, then rooks both colors, then queens both colors -- same phase
order as before (load-bearing for bvAttacks accumulation), just
sourced from a bitboard instead of a mixed list + runtime type
dispatch. Retires the cDefer/uDefer bookkeeping entirely -- with each
type its own direct walk, "rooks after minors" is just "do that walk
after this one," nothing to defer.
Verified genuinely behavior-neutral, not just crash-free: built the
pre-change and post-change binaries side by side and diffed
--batch --command output against tests/ecm_ringers.ep_ at sd10. Node
counts, scores, and PVs are byte-for-byte identical across all 11
positions; only wall-clock time and NPS differ, consistently in the
new version's favor (~3-5% faster on this suite, e.g. 1088239 nps ->
1143141 nps, 1560092 -> 1616844). Also verified via the normal
precommit_check.sh gate.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01P6g6iF6mD1Hau6nCZCzwYj
|
|
First piece type converted per board_representation/EVAL.md section 2:
pawns no longer write into rgSquare[c|8].bvAttacks at all. Every
consumer of "does a pawn attack this square" now reads
pos->bbPawnAttacks[2] directly -- a plain bitboard, computed fresh
each Eval() call from pos->bbPawns[] via the same shift-and-mask
technique generate.c's _GenerateAllPawnMovesBB already uses (zero
per-pawn mailbox iteration, vs. up to 16 delta+IS_ON_BOARD checks
before). Knight/bishop/rook/queen/king are unchanged -- still
populate/read their own bvAttacks bits (uMinor/uRook/uQueen/uKing)
the old way until their own conversions land.
Consumer changes, all in eval.c:
- UNSAFE_FOR_MINOR retired as a macro (it only ever tested the pawn
bit) -- its 3 call sites (knight, bishop x2) now test
bbPawnAttacks directly.
- UNSAFE_FOR_ROOK/_QUEEN masks narrowed to drop the now-dead pawn
bit; call sites OR in an explicit bbPawnAttacks test alongside the
narrowed bvAttacks read.
- Two direct .small.uPawn reads (bishop's transient-pawn mobility
credit, bishop's defended-pawn bonus) switched to bbPawnAttacks
tests.
- _EvalKing's bvAttack/bvDefend (the real king-danger computation)
OR the bitboard bit back in at both read points, careful to
preserve the original ordering where bvDefend must reflect the
king's own just-set defend bit.
- _WhoControlsSquareFast (used by passer-race/trapped-piece/danger
code) ORs the bitboard bit back into its g_SwapTable index at the
same bit position PAWN_BIT always occupied.
- Two bugs caught by manually auditing every remaining |8 site after
the fact (not by any test failing): _EvalPawns' own pawn-duo and
backward-pawn detection read bvAttacks.uWholeThing at a point in
Eval()'s sequence where only pawns could have written it -- once
pawns stopped writing there, both checks went permanently dead
silently. Fixed to read bbPawnAttacks directly. No self-test caught
this; it's exactly the gap EVAL.md section 5's planned exact-score
harness is meant to close.
EVAL_TIME instrumentation: split _EvalPawns' cycle counter into
pawn-hash hit/miss buckets (chess.h/eval.c/root.c), answering whether
the hash is still worth it now that attack-bit population is nearly
free. Measured on one sd12 benchmark position: hits average 90.4
cycles, misses average 1741.3 cycles (~19x), 97.15% hit rate -- the
hash stays a clear win; the miss cost was never mostly attack-bit
population (that's a separate ~1% bucket now, down from ~3.6%), it's
the isolated/doubled/duo/backward-pawn scoring loops, which still do
real per-pawn work on a miss.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01P6g6iF6mD1Hau6nCZCzwYj
|
|
redundant pawn-location bitboard
board_representation/EVAL.md: rewritten migration plan for a
bitboard-backed Eval() (mobility ray-walks + bvAttacks replacement),
plus a performance-philosophy section recording the profiling-first,
cut-aggressively-except-mobility/safety-awareness approach agreed on
this session, and findings on CountKingSafetyDefects' structural
inability to share bvAttacks-derived state with _EvalKing.
EVAL_TIME per-term instrumentation (chess.h/eval.c/root.c): breaks
the existing whole-Eval() cycle counter down by pawns/knight/bishop/
rook/queen/king, the always-paid pre-lazy-exit segment, and the
full-eval-only post-lazy segment, printed alongside the existing
"Avg. cpu cycles in eval" line. Diagnostic only (EVAL_TIME-gated),
no effect on the normal release profile.
Drop PAWN_HASH_ENTRY's bbPawnLocations[2]: it duplicated
POSITION's own incrementally-maintained bbPawns[2], rebuilt bit-by-bit
on every pawn-hash miss for no reason. eval.c now reads pos->bbPawns[]
directly; removed a stale per-iteration invariant assert in _EvalPawns
that only made sense when the bitboard was being built bit-by-bit in
that same loop.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01P6g6iF6mD1Hau6nCZCzwYj
|
|
bitboard helpers
- bitboard.c: CoorFromBitBoardRank1ToRank8 cleared the lowest set bit
unconditionally instead of the reported (highest) one, silently
mis-walking doubled-pawn files in eval.c's passed-pawn detection.
- search.c/searchsup.c: move GetLMRReduction's precondition checks from
inside the function to the caller in search.c (pre-existing work),
finishing the split with a matching gate in split.c's HelpSearch --
the parallel-search call site had no gate at all, letting it call
GetLMRReduction unconditionally (including for checking moves),
reachable only under real multithreading (--cpus > 1) and the
intermittent root cause of assertion crashes seen under --cpus 4.
- eval.c: redirect CountBits/CoorFromBitBoardRank8ToRank1/
CoorFromBitBoardRank1ToRank8 to inline compiler-builtin versions
(gated !CROUTINES) instead of the real out-of-line asm calls, on
eval.c's ~20 existing production call sites. CountBits' asm body
isn't O(1) popcnt, it's a Kernighan bit-clearing loop plus call
overhead, paid on every Eval() call.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Jntky4yGUTyQVaGCXms4F2
|
|
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
|
|
|
|
dispatch.
The per-square mobility ray-walk called through a function pointer for
every square visited (piece type varies square to square, so the CPU's
indirect-branch predictor couldn't learn it), and nearly every handler
reduced to a couple of constant increments and a stop/continue flag.
Replaced each PMOBILITY_HELPER table with a small case-tag table and an
inlined switch, dropping all now-dead handler functions and the
PMOBILITY_HELPER typedef. Also hoisted the ray-invariant rank/file
direction test (rook's "connected" bonus, queen's bishop/rook xray
cases) out of the per-square switch to compute once per ray instead.
Verified semantics-preserving: node counts, solve/fail sets, and PVs
are byte-for-byte identical to head_reference across all three curated
ECM suites (ringers/confident_quick/hard_quick) at sd 10. bench shows a
consistent ~6-7% NPS improvement over two back-to-back runs.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_012Q8wbZABsyG7PZQUd9WBAw
|
|
Eval() already detects trapped/attacked pieces (for search hints via
RecordEnprisePieceAtPly/RecordTrappedPiece) but never penalized them in
the static score. Add two named, DNA-visible constants: a larger flag
for the opponent-to-move/imminently-capturable case, a smaller one for
the own-move/still-might-escape case -- flat "this is bad" nudges, not
an attempt to price the material outcome, which search still owns.
Verified flat on ecm_ringers/ecm_confident_quick vs head_reference at
sd 10; ecm_hard_quick's lone flip (ECM.370) is a search-instability
artifact of that specific position (its true evaluation was still
moving through depth 14 in independent runs), not a real regression.
|
|
real king-safety bug found along the way.
A full-file pass over eval.c hunting for the "positional terms too
loud" feedback from real chess programmers, following the concrete
finding that Crafty prices most structural themes through one term
where this codebase spread the same theme across several (passed
pawns alone via 5-6 separate additive terms that can all fire for one
pawn). Two categories of fix, applied per the rule "if it's counting
the same thing twice, kill it; if it's a genuinely different angle on
the same theme, turn it down rather than remove it":
Pawns (pawn-hash cached, so free regardless of term count -- these are
data/magnitude fixes, not perf fixes):
- Removed ISOLATED_PAWN_PENALTY_BY_COUNT, a whole-position aggregate
that re-priced the same uIsolated[] count already reflected by
summing the per-pawn isolated term once per isolated pawn -- an
exact duplicate, not a different angle.
- CANDIDATE_PASSER_BY_RANK's "in endgame" bonus used to add the
exact same value a second time (a literal clone of the term just
added above it); now a /2 fractional modifier.
- CONNECTED_PASSERS_BY_RANK / SUPPORTED_PASSER_BY_RANK /
OUTSIDE_PASSER_BY_DISTANCE scaled to ~1/3 magnitude: each prices a
genuinely distinct angle on "how good is this passer" (connected
to a partner, pawn-defended, outside the opposing majority) and
can stack for the same pawn, so turned down rather than removed.
- ISOLATED_DOUBLED_PAWN turned down (-11 -> -5): a per-pawn kicker
that stacks with the whole-position DOUBLED_PAWN_PENALTY_BY_COUNT
aggregate for the isolated+doubled subset -- different angle
(single-worst-case flag vs. whole-position severity), not a
duplicate, but a real overlap worth trimming.
Pieces (non-cached, real per-node cost, so these are also legibility/
perf fixes, not just magnitude):
- Bishop: cut BISHOP_IN_CLOSED_POSITION outright -- it duplicated
bishop mobility rather than adding a distinct angle (mobility
already measures per-bishop diagonal blockage directly and more
precisely than a coarse whole-board proxy).
- Knight: killed a stale "don't block unmoved E2/D2 pawns" TODO
(opening-book territory, not eval's job) and "a knight with an
open file behind it is good" (dubious chess reasoning reusing an
unrelated table -- the same lookup as the backward-pawn-blockade
bonus, for a completely different concept).
- Rook: killed ROOK_TRAPPING_EKING (a rook on the 7th/8th aligned
with the enemy king is exactly the geometric pattern
CountKingSafetyDefects' CHECK_VECTOR scan already folds into
uPiecesPointingAtKing -- belongs in king safety, not a rook-
specific bolt-on). Also removed pFriendRook, dead in the same
block.
- Queen: killed "pointing near enemy K" (QUEEN_ATTACKS_SQ_NEXT_TO_
KING) -- computed from the queen's own mobility ray-cast, direct-
attacks only, duplicating what _EvalKing's real (non-lazy-estimate)
danger computation already reads from the identical attack-table
bits a few lines away.
- cTrapped fixed from a single COOR per color to a small [2][4] list
(_RecordTrappedCandidate): the old single-slot design let a later
piece's zero-mobility candidacy silently overwrite an earlier
one's on the same side, discarding a genuinely trapped-and-
attacked piece. This fed into search too (RecordTrappedPiece's
move-ordering hint), not just eval scoring. RecordTrappedPiece's
own per-ply single slot is left alone per design (would double the
cost on the branch that already computes it, this is the
innermost eval loop) -- now reports the MOST VALUABLE of the
candidates found, not just whichever was found last.
King (the actual regression-and-recovery of this session):
- Cutting the queen's "pointing near enemy K" term initially cost
real solves (117->110 on the sd10 curated suites) despite being a
correct duplication kill -- the general king-safety loop's
per-square attacker accounting was piece-type-blind (a queen
attacking a square near the king counted the same as a knight
doing the same geometric thing), so removing the one place that
priced queen-specific severity lost real fidelity, not just a
duplicate. Fixed properly: added KING_QUEEN_PROXIMITY_DANGER,
computed from bvAttacks[...].small.uQueen / .xray.uQueen bits the
king-safety loop already reads for every one of its 11 squares --
free (no new attack-table work) and more accurate than the killed
term (catches x-ray/latent queen threats it never did). Calibrated
against the killed term's own empirical magnitude (uNearKing * 8,
capped at 6) rather than guessed. Recovered to 118/191 (a new
session-best), now with the fidelity gap actually closed instead
of just removed.
- KING_SUPPORTING_OWN_PASSER_BY_RANK split out from
SUPPORTED_PASSER_BY_RANK, which _EvalKing's "kings in front of
passers" endgame bonus was silently reusing -- pawn-support and
king-escort are different concepts (fires when the KING stands
next to its own passer, not when a pawn does); scaling the shared
table down for its real purpose was silently also scaling the
unrelated king-escort bonus. Seeded with the table's original
(pre-scaling) hand-tuned magnitude.
- Collapsed three copy-pasted file-scan blocks (c-1/c/c+1, identical
logic repeated three times) into one loop -- confirmed
behaviorally neutral by isolated sd10 suite testing before
landing alongside the king-safety content changes.
Net result across the three curated suites (sd10, vs. the hand-tuned+
bugfix baseline this built on): 117 -> 118, a new session best, with
every intermediate checkpoint tested via EVAL_DUMP verification +
precommit_check.sh + sd10 sweep before moving to the next change.
Deliberately deferred, written down for a future session rather than
attempted here: a holistic king-safety overhaul (the piece-type-
tropism inconsistency across knight/bishop/queen/the general
CountKingSafetyDefects scan goes deeper than tonight's scoped fixes),
recalibrating EstimatePositionalScore's iKingSwingP90 lazy-eval margin
table (the instrumentation that built it no longer exists in this
tree, and today's changes have already shifted the true swing
distribution it was calibrated against), and training a small king-
danger classifier from TWIC checkmate games (snapshot king safety
features at -10/-15 moves from real checkmates, not resignations) to
calibrate whichever of the above happens first.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01M9ZDiJhiUajUxh95mTXCFJ
|
|
a stale king-safety data bug found along the way.
The Texel/coordinate-descent auto-tuning pass (started at 29d73f4) left
several eval terms with non-monotonic or outright sign-flipped values
that several ASSERTs had to be silently commented out to tolerate
(e.g. BACKWARD_SHIELDED_BY_LOCATION scoring a structural pawn defect as
a +12..+17 bonus on most squares, PASSER_BONUS_AS_MATERIAL_COMES_OFF
staying flat until the defending side was down to almost nothing).
Restored all 54 differing constant tables to their last hand-tuned
values (commit df8facc, pre-dating 29d73f4) mechanically -- table
names/shapes are identical between the two commits, only values
differ, so this is a pure data restore with none of the surrounding
code-structure changes since df8facc reverted.
Also fixes a real bug found while investigating: pos->uPiecesPointingAtKing[]
was only refreshed inside EstimatePositionalScore's lazy-eval-margin
path (eval.c ~5648), but _EvalKing reads it unconditionally on every
full eval. Whenever a node's cheap material+pawn score wasn't close
enough to the alpha/beta window to trigger that lazy-margin branch, the
full eval proceeded straight to _EvalKing using a stale
uPiecesPointingAtKing value left over from a prior, unrelated node --
silent, intermittent noise in king-safety scoring on an unpredictable
subset of evaluations. Introduced 2026-08-24/26 (29d73f4, 7857096), so
it predates and was baked into the Texel tuning pass being reverted
here. Fixed by computing it once in an else branch when the lazy-margin
path isn't taken, so it's refreshed exactly once per full eval either
way (this is the innermost eval loop, so avoided doubling the cost on
the branch that already computes it).
sd10/sn5m results across the three curated suites (vs. head_reference,
the prior Texel-tuned HEAD):
sd10: ringers 9/11 (was 10), confident 85/90 (was 88), hard 23/90 (was 17) -- total 117 vs 115
sn5m: ringers 11/11 (was 10), confident 87/90 (was 89), hard 14/90 (was 13) -- total 112 vs 112
Net win at sd10, wash at sn5m, in both cases with a large swing toward
ecm_hard_quick -- consistent with hand-tuned values being more
internally coherent (monotonic curves, no sign flips, no double-counted
whole-position aggregates layered on top of already-summed per-item
terms) even though they were never retuned against this specific suite
or these specific opponents.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01M9ZDiJhiUajUxh95mTXCFJ
|
|
Finishes work left half-done in 7857096 ("Replace ctx->uPositional with
a data-calibrated Eval() return value"): that commit added Eval()'s new
piPositional out-param but never migrated GetRoughEvalScore onto it, so
GetRoughEvalScore's mid/deep-tree fallback kept reading the old
ctx->uPositional field -- a per-thread EWMA written only on full-eval
calls and never touched by the (far more common) lazy-eval path, so it
carried a stale value from whatever unrelated position last triggered a
full eval, potentially many nodes/plies away. Combined with EVAL_HASH
being long since disabled (its probe branch already dead), every
GetRoughEvalScore call past ply 4 was effectively "material + garbage."
Fixed by having GetRoughEvalScore just call Eval() directly -- its own
lazy-exit machinery already is the cheap, calibrated estimate this
function exists to provide, so there's no separate estimator to
maintain. Removed ctx->uPositional entirely (struct field, its EWMA
update in eval.c, both root.c init sites, split.c's cross-split
propagation, testeval.c's reset) along with the entire EVAL_HASH
subsystem (struct, table, Probe/StoreEvalHash, main.c's now-dead
reporting branch, the GNUmakefile flag) -- confirmed unused elsewhere
and explicitly being cut for good, not coming back in this form.
Also fixed GetRoughEvalScore's prototype being wrongly declared inside
#ifdef EVAL_HASH in chess.h even though the function itself is defined
and called unconditionally -- this was the source of the recurring
"call to undeclared function 'GetRoughEvalScore'" implicit-declaration
warning seen throughout this session's builds.
Separately, fixed QSearch to match its own documented intent: the
en-prise/trapped-piece "don't let this side stand pat" check now only
fires if the side hasn't already been allowed to stand pat earlier in
this qsearch line (matching the comment above it, which already said
this but the code never implemented it).
Verified against baseline/typhoon_baseline (pristine, pre-session) on
ecm_ringers.ep_ (4), ecm_hard_quick.ep_ (50-sample), and
ecm_confident_quick.ep_ (40) at sn=5M, --cpus 1, book disabled:
pristine baseline solves 3/50 on the hard sample; this commit solves
6/50, with the stand-pat fix and GetRoughEvalScore fix each
contributing +1 independently confirmed. No regressions on the other
two suites (4/4 and 40/40 unchanged throughout).
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YGSMkwjqiCk4XhbfN7ugD2
|
|
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.
|
|
uPositional was a per-thread EWMA of abs(material - true score) used to
size lazy-eval and futility margins. It was history-derived (reflecting
whatever recent, unrelated positions looked like) rather than derived
from the position actually being margined, and its update/consumption
was tangled with EVAL_HASH (now disabled).
Eval() now takes an optional SCORE *piPositional out-param and fills it
in on every return path: exact (abs(material-delta)) on a full eval,
or an estimate from a new EstimatePositionalScore() on a lazy exit.
EstimatePositionalScore()'s two terms (king-safety-defect-bucketed, and
a flat residual for mobility/passers/everything else) are calibrated
from ~1.6M measured full-eval samples (p90 of the actual swing), not
guessed -- an initial guessed version measurably regressed ECM solve
rate (630 vs a 650 baseline at sn=4M); the recalibrated version is back
at parity (649/879).
search.c's qsearch futility now reads the value Eval() just computed
instead of the stale/shared ctx field. Also removes QSearchInDangerNoStandPat
and SideCanStandPat, dead since the danger-hash check that fed them was
already commented out (e08387a) -- they depended on the same enprise/
trapped-piece data this conversation is about to move off of
g_PositionHash entirely.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
|
|
|
|
|
|
it found)
|
|
|
