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Diffstat (limited to 'src/board_representation/MIGRATION.md')
| -rw-r--r-- | src/board_representation/MIGRATION.md | 66 |
1 files changed, 50 insertions, 16 deletions
diff --git a/src/board_representation/MIGRATION.md b/src/board_representation/MIGRATION.md index f8bccb1..57ca7f9 100644 --- a/src/board_representation/MIGRATION.md +++ b/src/board_representation/MIGRATION.md @@ -14,10 +14,14 @@ references accordingly; where useful, dropped content is preserved inline as a note rather than deleted, so a future session designing the separate migration doesn't have to rediscover it from git history. -**Status: sections 1-2 (`bbPieces`) and section 3 (`bbPieces`/`bbPawns`-backed -`_WhoAttacksSquareBB`/`_GetAttacksBB`, not yet wired into the -`GetAttacks` macro) implemented, verified, and committed. Sections 4 -(partially done, folded into section 3's own testing)-8 not started.** +**Status: sections 1-3 (`bbPieces`/`bbPawns`-backed +`_WhoAttacksSquareBB`/`_GetAttacksBB`) and section 6 (the +`GETATTACKS_BITBOARD` toggle, `_GetAttacksBB` now reachable from real +search when enabled) implemented, verified, and committed. Section 4 +items 1-3 done (folded into sections 3/6's own testing); items 4-5 and +sections 5's second half/7 -- the whole-engine curated-suite and +`match_play.py` gates -- not started, now genuinely unblocked since +section 6 exists. Section 8 not started.** See the per-section status notes below for specifics. Context: a prior pass of this session added occupancy-bitboard-driven @@ -444,10 +448,10 @@ sequence. above -- also fixed a latent `bbPieces`/`bbPawns` maintenance gap in `GenerateRandomLegalPosition` found while running this. 3. **`precommit_check.sh`** as always, for the crash/assert layer. - **DONE** for `_GetAttacksBB`'s current (not-yet-wired-in) state -- - clean. Should be re-run once section 6's toggle actually flips - `GetAttacks` to the bitboard implementation, since nothing has - exercised that live yet. + **DONE**, both without and with section 6's toggle + (`GETATTACKS_BITBOARD=1`) -- clean in both configurations, the + latter run confirming `_GetAttacksBB` live end-to-end in real + search, not just the isolated harness. 4. **SEE-value diffing at the position level**: since `SEE()` returns a single integer per move (not a board eval), the equivalent of the Eval work's "150-position score-identity diff" is a diagnostic @@ -503,16 +507,46 @@ visible in isolation. Two tiers, both required before wiring in: to production wiring again. Not started -- requires section 6's toggle to exist first. -## 6. Dual-support / toggle strategy +## 6. Dual-support / toggle strategy -- DONE Same `#define` pattern already established for the Eval occupancy work -(`ROOK_OCCUPANCY_EVAL` et al.): `GETATTACKS_BITBOARD`, flipping which -implementation `chess.h`'s `GetAttacks` macro/prototype resolves to -(alongside the existing `CROUTINES` old/new(asm) switch -- this becomes a -three-way choice: `SlowGetAttacks` (C mailbox), asm `GetAttacks` (x86/x64 -mailbox), `_GetAttacksBB` (new)). Not started -- `_GetAttacksBB` is -still a side-by-side PoC, called only from the test/bench harness, not -reachable from the `GetAttacks` macro yet. +(`ROOK_OCCUPANCY_EVAL` et al.): `GETATTACKS_BITBOARD` (`GNUmakefile` +build flag, `-DGETATTACKS_BITBOARD`), flipping which implementation +`chess.h`'s `GetAttacks` macro resolves to -- a three-way choice +alongside the existing `CROUTINES` switch: `_GetAttacksBB` (new, +bitboard) if `GETATTACKS_BITBOARD` is defined, else `SlowGetAttacks` +(C mailbox) if `CROUTINES` is defined, else the real asm `GetAttacks` +(x86/x64 mailbox, the default). `_GetAttacksBB` is now reachable from +every real `GetAttacks` call site (`generate.c`'s check-detection +call, `see.c`'s `SEE()`, `searchsup.c`) when the flag is set, not just +the test/bench harness. + +**Found and fixed while wiring this up**: `testsee.c`'s own +`TestGetAttacks`/benchmark code calls the identifier `GetAttacks` to +mean "the real asm/CROUTINES baseline" -- but once the macro can +resolve to `_GetAttacksBB`, those same calls would silently become +`_GetAttacksBB` compared against itself, turning the correctness sweep +and the "asm vs. new" benchmark into false-positive no-ops. Fixed with +a local `#undef GetAttacks` right after `#include "chess.h"` in +`testsee.c`, so the harness always reaches the true baseline +implementation regardless of which implementation is live in +production -- the harness's job is validating the new implementation +against a fixed reference, not testing the engine's current +configuration against itself. + +**Verified with the toggle live**: `gmake TEST=1 GETATTACKS_BITBOARD=1` +-- self-test suite passes (including the corrected benchmark, still +reporting real asm vs. `_GetAttacksBB` correctly, same ~0.52-0.92x +numbers as section 3), and a real `Search()` call in the self-test +suite completed normally with `_GetAttacksBB` live in `SEE()`/move +generation's check-detection path, not just the isolated harness. +`precommit_check.sh GETATTACKS_BITBOARD=1` (env-var propagation into +`gmake` verified directly by grepping the resulting build logs for +`-DGETATTACKS_BITBOARD`) -- both the `TEST=1` self-test and `DEBUG=1` +smoke test (10 random ECM positions, `sd 4`) pass clean with the +bitboard implementation live end-to-end. Default build (no flag) +confirmed unaffected -- `GetAttacks` still resolves to the real asm +function unless the flag is explicitly passed. `bbPieces`/`bbPawns` maintenance itself is **always on** regardless of this toggle -- it's cheap enough that gating it adds complexity for no |