King-safety recalibration, lazy-eval material floor, eval hot-path trimming

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

1 files changed, 16 insertions, 1 deletions

diff --git a/src/search.c b/src/search.c
index 1b83891..25318ed 100755
--- a/src/search.c
+++ b/src/search.c
@@ -1249,7 +1249,22 @@ QSearchFromCheckNoStandPat(IN SEARCHER_THREAD_CONTEXT *ctx,
         if ((pf->uQsearchDepth < pf->uQsearchCheckDepth) &&
             (pf->uQsearchDepth < g_uIterateDepth / 4) &&
             (pf->fCouldStandPat[pos->uToMove] == FALSE) &&
-            (CountKingSafetyDefects(pos, pos->uToMove) > 2))
+            //
+            // Threshold doubled 2026-09-06 (board_representation/
+            // EVAL.md section 9): was ">2", tuned against the old
+            // CHECK_VECTOR-based CountKingSafetyDefects. The bitboard
+            // rewrite (real blocker-aware slider attacks, queen 2x
+            // weighting) runs systematically hotter for the same
+            // underlying danger, so the un-rescaled old threshold was
+            // firing far more liberally than intended -- observed
+            // directly as a runaway check-extension cascade (85x+
+            // branching for a single ply) on a real position. Not yet
+            // independently recalibrated against real data the way
+            // iKingSwingP90 was; doubling is a stopgap matching the
+            // rough inflation this counter picked up, pending a real
+            // measurement.
+            //
+            (CountKingSafetyDefects(pos, pos->uToMove) > 4))
         {
             if ((uMoveCount == 1) ||
               (NUM_KING_MOVES(ctx, ctx->uPly) == 0) ||