diff options
Diffstat (limited to 'src/search.c')
| -rwxr-xr-x | src/search.c | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/src/search.c b/src/search.c index 28f6f3d..29bbc66 100755 --- a/src/search.c +++ b/src/search.c @@ -383,6 +383,13 @@ Search(IN SEARCHER_THREAD_CONTEXT *ctx, ASSERT(!InCheck(pos, pos->uToMove)); GenerateMoves(ctx, mvHash, GENERATE_ALL_MOVES); } + + // The threat/multi-check/no-legal-king-move bonuses above + // are independent and can stack past ONE_PLY; clamp the + // combined per-position extension to what the rest of the + // code (e.g. split.c's HelpSearch) assumes is the max for + // a single node. + iOrigExtend = MIN(iOrigExtend, ONE_PLY); // fall through case PREPARE_TO_TRY_MOVES: @@ -527,6 +534,16 @@ Search(IN SEARCHER_THREAD_CONTEXT *ctx, uDepth, &iExtend); + // Cap how many extension plies this line may spend in total + // (root to here) so that a chain of checks/threats/etc. can't + // stall uDepth's descent indefinitely and burn the entire + // MAX_PLY_PER_SEARCH ply budget on one forcing sequence. + if (iExtend > 0) + { + iExtend = MIN(iExtend, + MAX(MAX_EXTEND_PER_LINE - pf->iCumulativeExtend, 0)); + } + // Decide whether or not to do history pruning if (TRUE == WeShouldDoHistoryPruning(iRoughEval, iAlpha, @@ -561,6 +578,7 @@ Search(IN SEARCHER_THREAD_CONTEXT *ctx, // Compute the next search depth for this move/subtree. uNextDepth = uDepth - ONE_PLY + iExtend; if (uNextDepth >= MAX_DEPTH_PER_SEARCH) uNextDepth = 0; + pf->iCumulativeExtend += iExtend; ASSERT(pf->fAvoidNullmove == FALSE); if (iBestScore == -INFINITY) { @@ -586,6 +604,7 @@ Search(IN SEARCHER_THREAD_CONTEXT *ctx, iScore = -Search(ctx, -iBeta, -iAlpha, uNextDepth); } UnmakeMove(ctx, mv); + pf->iCumulativeExtend -= iExtend; ASSERT(PositionsAreEquivalent(pos, &pi->sPosition)); if (WE_SHOULD_STOP_SEARCHING) { @@ -1327,6 +1346,7 @@ QSearch(IN SEARCHER_THREAD_CONTEXT *ctx, -iAlpha); pf->uQsearchDepth--; UnmakeMove(ctx, mv); + if (WE_SHOULD_STOP_SEARCHING) goto end; if (iScore > iBestScore) { @@ -1360,7 +1380,6 @@ QSearch(IN SEARCHER_THREAD_CONTEXT *ctx, } } } - if (WE_SHOULD_STOP_SEARCHING) goto end; } } ASSERT(iBestScore > -NMATE); |