Remove unneeded branch

vondele · lantonov · commit a29ce3c01031 · 2018-09-30T14:56:20.000+03:00
Storing unconditionally the current generation and bound is equivalent to master. Part of the condition was added as a speed optimization in official-stockfish#429. Here the branch is fully eliminated. passed STC single-threaded: LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 73515 W: 16378 L: 16359 D: 40778 http://tests.stockfishchess.org/tests/view/5b2fc38c0ebc5902b2e57fd5 passed STC multi-threaded: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 63725 W: 12916 L: 12874 D: 37935 http://tests.stockfishchess.org/tests/view/5b307b8f0ebc5902b2e5895f The multithreaded test was run after a plausible suggestion by @mstembera that the effect of this could be larger with many cores. The result seems to indicate this doesn't really matter on the 8core architecture abundantly available on fishtest. No functional change
diff --git a/src/tt.cpp b/src/tt.cpp
@@ -119,8 +119,7 @@ TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
   for (int i = 0; i < ClusterSize; ++i)
       if (!tte[i].key16 || tte[i].key16 == key16)
       {
-          if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
-              tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
+          tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
 
           return found = (bool)tte[i].key16, &tte[i];
       }

Original file line number	Diff line number	Diff line change
`@@ -119,8 +119,7 @@ TTEntry* TranspositionTable::probe(const Key key, bool& found) const {`
`119`	`119`	`for (int i = 0; i < ClusterSize; ++i)`
`120`	`120`	`if (!tte[i].key16 \|\| tte[i].key16 == key16)`
`121`	`121`	`{`
`122`		`- if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)`
`123`		`- tte[i].genBound8 = uint8_t(generation8 \| tte[i].bound()); // Refresh`
	`122`	`+ tte[i].genBound8 = uint8_t(generation8 \| tte[i].bound()); // Refresh`
`124`	`123`
`125`	`124`	`return found = (bool)tte[i].key16, &tte[i];`
`126`	`125`	`}`