Don't insert pv back into tt

This code was added before the accurate pv patch, when
we retrieved PV directly from TT.

It's not required for correct (and long) PVs any more and
should be safe to remove it.

Also, allowing helper threads to repeatedly over-write
TT doesn't seem to make sense(that was probably an un-intended
side-effect of lazy smp). Before Lazy SMP only Main Thread used
to run ID loop and insert PV into TT.

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 74346 W: 13946 L: 13918 D: 46482

LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 47265 W: 6531 L: 6447 D: 34287

bench: 8819179

diff --git a/src/search.cpp b/src/search.cpp
index 995204f34aab2bf4cca090eb3e66c41f1c857c8a..0b4125fcdd6ccf05279c848c1257eed89c042343 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -413,11 +413,6 @@ void Thread::search() {
               // search the already searched PV lines are preserved.
               std::stable_sort(rootMoves.begin() + PVIdx, rootMoves.end());
 
               // search the already searched PV lines are preserved.
               std::stable_sort(rootMoves.begin() + PVIdx, rootMoves.end());
 

-              // Write PV back to the transposition table in case the relevant
-              // entries have been overwritten during the search.
-              for (size_t i = 0; i <= PVIdx; ++i)
-                  rootMoves[i].insert_pv_in_tt(rootPos);
-

               // If search has been stopped, break immediately. Sorting and
               // writing PV back to TT is safe because RootMoves is still
               // valid, although it refers to the previous iteration.
               // If search has been stopped, break immediately. Sorting and
               // writing PV back to TT is safe because RootMoves is still
               // valid, although it refers to the previous iteration.


@@ -1564,33 +1559,6 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
 }
 
 
 }
 
 

-/// RootMove::insert_pv_in_tt() is called at the end of a search iteration, and
-/// inserts the PV back into the TT. This makes sure the old PV moves are searched
-/// first, even if the old TT entries have been overwritten.
-
-void RootMove::insert_pv_in_tt(Position& pos) {
-
-  StateInfo state[MAX_PLY], *st = state;
-  bool ttHit;
-
-  for (Move m : pv)
-  {
-      assert(MoveList<LEGAL>(pos).contains(m));
-
-      TTEntry* tte = TT.probe(pos.key(), ttHit);
-
-      if (!ttHit || tte->move() != m) // Don't overwrite correct entries
-          tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE,
-                    m, VALUE_NONE, TT.generation());
-
-      pos.do_move(m, *st++, pos.gives_check(m, CheckInfo(pos)));
-  }
-
-  for (size_t i = pv.size(); i > 0; )
-      pos.undo_move(pv[--i]);
-}
-
-

 /// RootMove::extract_ponder_from_tt() is called in case we have no ponder move
 /// before exiting the search, for instance, in case we stop the search during a
 /// fail high at root. We try hard to have a ponder move to return to the GUI,
 /// RootMove::extract_ponder_from_tt() is called in case we have no ponder move
 /// before exiting the search, for instance, in case we stop the search during a
 /// fail high at root. We try hard to have a ponder move to return to the GUI,

diff --git a/src/search.h b/src/search.h
index 73d8cdfa200cd28527f0e43aad2c868516008f81..599d058fa7d018454ea481f30a6448f079a53e87 100644 (file)
--- a/src/search.h
+++ b/src/search.h
@@ -59,7 +59,6 @@ struct RootMove {
 
   bool operator<(const RootMove& m) const { return m.score < score; } // Descending sort
   bool operator==(const Move& m) const { return pv[0] == m; }
 
   bool operator<(const RootMove& m) const { return m.score < score; } // Descending sort
   bool operator==(const Move& m) const { return pv[0] == m; }

-  void insert_pv_in_tt(Position& pos);

   bool extract_ponder_from_tt(Position& pos);
 
   Value score = -VALUE_INFINITE;
   bool extract_ponder_from_tt(Position& pos);
 
   Value score = -VALUE_INFINITE;