Make bitboard move generation unconditional; delete the mailbox fallback

All GENERATE_*_BITBOARD/EXPOSESCHECK_BITBOARD/ISATTACKED_BITBOARD/
UNBLOCKED_BITBOARD flags were already default-on (ifndef
DISABLE_BITBOARD_MOVEGEN); this removes that opt-out entirely (GNUmakefile)
and deletes the mailbox-era code the flags used to toggle between, since
there's no longer a build configuration that still needs it:

- generate.c: the mailbox per-piece generators and escape-generators
  (GenerateKnight/GenerateWhiteKnight/GenerateBishop/GenerateRook/
  GenerateQueen/GenerateBlackKing/GenerateWhiteKing/GenerateWhitePawn/
  GenerateBlackPawn and their SaveMe* escape-generator counterparts),
  _FindUnblockedSquares and its DEBUG-build cross-check inside
  _FindUnblockedSquaresBB, and the dispatch-table #if/#else pairs that
  chose between mailbox and bitboard functions (now unconditionally
  bitboard). WouldGiveCheck simplified to its UNBLOCKED_BITBOARD-only
  body. g_iBDeltas/g_iRDeltas (orphaned once their only consumers were
  deleted) removed; g_iNDeltas (still used by data.c's InitMagic) moved
  there, next to its real consumer.
- movesup.c: mailbox FasterExposesCheck/ExposesCheck/ExposesCheckEp/
  IsAttacked/InCheck deleted; chess.h's three-way macro choice
  simplified to a direct #define onto the BB versions (ExposesCheckBB/
  IsAttackedBB/etc. are simply "the" implementation now).
- testsee.c/testgenerate.c: deleted the mailbox-vs-BB comparison/speed
  harnesses that only existed to validate code just removed
  (TestIsAttackedBB, TestGenerateKnightSpeed/KingSpeed/RookSpeed/
  BishopSpeed/QueenSpeed, TestFindUnblockedSquaresSpeed's mailbox arm).
  TestGetAttacks and the _GenerateAllMoves-vs-_GenerateAllMovesBB
  dispatch-overhead benchmark are unaffected -- GetAttacks' mailbox/asm
  predecessors were already retired independently, and that pair
  compares two still-live BB-only dispatch strategies, not mailbox vs
  BB.

Verified: clean release build and a clean DEBUG=1 TEST=1 self-test run
(move generation, perft-style legal-move checks, SAN/ICS parsing,
search smoke test) with no assertion failures.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

1 files changed, 0 insertions, 125 deletions

diff --git a/src/testsee.c b/src/testsee.c
index 240ac39..4afe60f 100644
--- a/src/testsee.c
+++ b/src/testsee.c
@@ -26,19 +26,6 @@ Revision History:
 
 #include "chess.h"
 
-// Same reasoning, for IsAttacked/InCheck (board_representation/
-// MOVEGEN_MIGRATION.md section 6b's ISATTACKED_BITBOARD toggle):
-// TestIsAttackedBB below must always be able to call the real mailbox
-// IsAttacked by name and compare it against IsAttackedBB explicitly,
-// regardless of which one chess.h's macro currently routes plain
-// "IsAttacked(...)" calls to elsewhere in the engine.
-#ifdef IsAttacked
-#undef IsAttacked
-#endif
-#ifdef InCheck
-#undef InCheck
-#endif
-
 #ifdef TEST_BROKEN
 ULONG g_uRootOnMove;
 
@@ -264,118 +251,6 @@ TestGetAttacks(void)
     }
 }
 
-// board_representation/MOVEGEN_MIGRATION.md section 6b: direct
-// comparison harness for IsAttacked/IsAttackedBB, same pattern as
-// TestGetAttacks above -- mailbox vs. bitboard, same inputs, must
-// match exactly. This is the piece ExposesCheckBB didn't get before
-// shipping and had to be debugged the hard way instead (two real bugs
-// found via TestSan/perft/DEBUG-assert failures rather than a direct
-// comparison); doing it properly here from the start.
-void
-TestIsAttackedBB(void)
-{
-    POSITION pos;
-    ULONG u;
-    COOR c;
-    ULONG uSide;
-    FLAG fMailbox, fBB;
-
-    Trace("Testing IsAttacked...\n");
-    for (u = 0; u < 20000; u++)
-    {
-        GenerateRandomLegalPosition(&pos);
-        FOREACH_SQUARE(c)
-        {
-            if (!IS_ON_BOARD(c)) continue;
-            for (uSide = BLACK; uSide <= WHITE; uSide++)
-            {
-                fMailbox = IsAttacked(c, &pos, uSide);
-                fBB = IsAttackedBB(c, &pos, uSide);
-                if (fMailbox != fBB)
-                {
-                    UtilPanic(TESTCASE_FAILURE,
-                              &pos,
-                              "IsAttacked/IsAttackedBB mismatch",
-                              NULL, NULL,
-                              __FILE__, __LINE__);
-                }
-            }
-        }
-        for (uSide = BLACK; uSide <= WHITE; uSide++)
-        {
-            fMailbox = InCheck(&pos, uSide);
-            fBB = InCheckBB(&pos, uSide);
-            if (fMailbox != fBB)
-            {
-                UtilPanic(TESTCASE_FAILURE,
-                          &pos,
-                          "InCheck/InCheckBB mismatch",
-                          NULL, NULL,
-                          __FILE__, __LINE__);
-            }
-        }
-    }
-
-    //
-    // Speed: same isolated cycles/call methodology as TestGetAttacks
-    // above, interleaved call-by-call to cancel shared-box noise.
-    //
-    {
-        static const char *rgszFen[3] =
-        {
-            "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
-            "r1bq1rk1/pp2bppp/2n1pn2/2pp4/3P4/2NBPN2/PP3PPP/R1BQ1RK1 w - - 0 1",
-            "8/5k2/8/3K4/8/8/8/4R3 w - - 0 1",
-        };
-        static const char *rgszLabel[3] =
-        {
-            "opening   ", "middlegame", "endgame   ",
-        };
-        POSITION posBench;
-        UINT64 u64MailboxTotal, u64BBTotal, u64Start;
-        ULONG uIter;
-        ULONG uSq;
-        COOR cBench;
-        ULONG uSideBench;
-        const ULONG uCallsPerPosition = 200000;
-        FLAG fSink;
-
-        Trace("Benchmarking IsAttacked: mailbox vs IsAttackedBB "
-              "(interleaved, %lu calls/position)...\n",
-              uCallsPerPosition);
-        for (u = 0; u < 3; u++)
-        {
-            FenToPosition(&posBench, (char *)rgszFen[u]);
-            u64MailboxTotal = 0;
-            u64BBTotal = 0;
-            for (uIter = 0; uIter < uCallsPerPosition; uIter++)
-            {
-                uSq = uIter % 64;
-                cBench = BIT_NUMBER_TO_COOR(uSq);
-                uSideBench = uIter & 1;
-                if (!IS_ON_BOARD(cBench)) continue;
-
-                u64Start = SystemReadTimeStampCounter();
-                fSink = IsAttacked(cBench, &posBench, uSideBench);
-                u64MailboxTotal += (SystemReadTimeStampCounter() - u64Start);
-
-                u64Start = SystemReadTimeStampCounter();
-                fSink = IsAttackedBB(cBench, &posBench, uSideBench);
-                u64BBTotal += (SystemReadTimeStampCounter() - u64Start);
-                (void)fSink;
-            }
-            printf(" %s: mailbox %" COMPILER_LONGLONG_UNSIGNED_FORMAT
-                   " cycles/call, IsAttackedBB %"
-                   COMPILER_LONGLONG_UNSIGNED_FORMAT " cycles/call "
-                   "(BB is %.2fx mailbox)\n",
-                   rgszLabel[u],
-                   u64MailboxTotal / uCallsPerPosition,
-                   u64BBTotal / uCallsPerPosition,
-                   (double)u64BBTotal / (double)u64MailboxTotal);
-        }
-    }
-}
-
 // SeeFastSign (see.c) is a sign-only shortcut for SEE(pos, mv) >= 0 --
 // GetMoveSee's only consumer (ComputeMoveExtension, searchsup.c) never
 // reads the magnitude, only the sign, so this skips SEE()'s list-