Allowing singular extension in mate positions
Drop useless condition
abs(ttValue) < VALUE_KNOWN_WIN
And extend singular extension search to cases when ttValue
stores a mate score. This improves mate finding and does
not introduce any regression.
Yery tested this patch against current master on the 6500+
Chest mate suite with 200K fixed nodes:
shortest mates found: master: 1206 patch:1205
any mate found: master: 1903 patch: 2003
with 1 sec time:
shortest mates found: master: 2667 patch: 2628
any mate found: master: 3585 patch: 3646
Verified for no regression:
STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 25655 W: 4578 L: 4465 D: 16612
LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 66247 W: 8618 L: 8557 D: 49072
bench: 6335042