|
killer-mate edge case; fix PV-display cycle hang.
_ShouldWeConsiderThisMove (QSearch's move-consider gate) read the raw,
move-ordering-biased mvf[].iValue directly instead of going through
ComputeMoveScore, so it inherited the same +120-ish flat bias (plus
small MVV-LVA nudges) on winning/even captures that ComputeMoveScore
was already fixed to strip out. Fixed via the same MOVE_SCORE_ORDERING_BIAS
subtraction, now factored into a shared chess.h macro. Restoring the old
effective leniency required an explicit QSEARCH_CONSIDER_MARGIN (120,
A/B'd against 0/60/120 on ecm_ringers/confident_quick/hard_quick) rather
than assuming the bug's magnitude was itself a meaningful margin -- net
effect vs the pre-fix baseline is -2 solves on hard_quick, accepted as
the cost of correctness (see lmr_testing/RESULTS.md for the full sweep).
ComputeMoveScore separately mishandled quiet killer-mate moves: they can
reach SORT_THESE_FIRST via generate.c's killer-mate bonus (unrelated to
the capture-bias path), so the bias-subtraction was wrongly applied to a
move that never had that bias. Gated the subtraction on
IS_CAPTURE_OR_PROMOTION(mv); quiet moves (including killer-mate ones) now
correctly collapse to 0, per the function's contract of estimating a
move's value on the 100=1-pawn axis. Measured as a no-op on all three
suites -- rare in practice, but a real correctness fix. Left a comment
documenting two candidate refinements for scoring quiet moves as
non-uniform future work, deliberately not implemented (each needs its
own isolated test).
FinishPVTailFromHash (cosmetic PV-display hash-walk, used only for
printing) had no cycle detection, so a drawish/repeating position could
spin until the output buffer filled instead of terminating naturally.
Added visited-position-signature tracking and a <REP> marker.
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.
|
