Chess engine: Stockfish 20011222

Stockfish - UCI chess engine, compiled by Xoto10

Smarter time management near stop limit

This patch makes Stockfish search same depth again if > 60% of optimum time is already used, instead of trying the next iteration. The idea is that the next iteration will generally take about the same amount of time as has already been
used in total. When we are likely to begin the last iteration, as judged by total time taken so far > 0.6 * optimum time, searching the last depth again instead of increasing the depth still helps the other threads in lazy SMP and prepares better move ordering for the next moves.

STC :
LLR: 2.95 (-2.94,2.94) {-1.00,3.00}
Total: 13436 W: 2695 L: 2558 D: 8183 Elo +3.54
Ptnml(0-2): 222, 1538, 3087, 1611, 253

LTC :
LLR: 2.94 (-2.94,2.94) {0.00,2.00}
Total: 32160 W: 4261 L: 4047 D: 23852 Elo +2.31
Ptnml(0-2): 211, 2988, 9448, 3135, 247

The code was revised as suggested by @vondele for multithreading:

STC (8 threads):
LLR: 2.95 (-2.94,2.94) {0.00,2.00}
Total: 16640 W: 2049 L: 1885 D: 12706 Elo +3.42
Ptnml(0-2): 119, 1369, 5158, 1557, 108

LTC (8 threads):
LLR: 2.95 (-2.94,2.94) {-1.00,3.00}
Total: 16536 W: 2758 L: 2629 D: 11149 Elo +2.71
Ptnml(0-2): 182, 1758, 4296, 1802, 224

Thanks to those discussing Stockfish lazy SMP on fishcooking which made me try this, and to @vondele for suggestions and doing related tests.
Bench: 4586187


Rating JCER=3344

Stockfish 20011222 - download