Fix TB score output in UCI without using TB

This is a rewrite of the fix introduced for
https://github.com/official-stockfish/Stockfish/issues/4413 in
https://github.com/official-stockfish/Stockfish/pull/4591 by @windfishballad it
targets only the relevant part of this issue that returns TB scores (CP 20000)
without using TB due to the downgrading of potentially false mates from the TT
to an optimal TB score.

the difference is that it is a much clearer code that introduces a separate
TB_VALUE constant to account for a correct distance from the TB_VALUE with
MAX_PLY.

the originally posted position in the issue does not trigger the problem
anymore, so here is a new position to test:
```
position fen 3k4/8/8/8/8/8/3BN3/3K4 w - - 0 1
go infinite
```

Passed non-regression STC:
https://tests.stockfishchess.org/tests/view/65578994136acbc57353b258
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 119264 W: 29993 L: 29863 D: 59408
Ptnml(0-2): 372, 13692, 31379, 13812, 377

Passed non-regression LTC:
https://tests.stockfishchess.org/tests/view/6558323f136acbc57353c1ca
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 237834 W: 58791 L: 58792 D: 120251
Ptnml(0-2): 193, 26200, 66111, 26241, 172

fixes https://github.com/official-stockfish/Stockfish/issues/4413
closes https://github.com/official-stockfish/Stockfish/pull/4591
closes https://github.com/official-stockfish/Stockfish/pull/4882

Bench: 1305821
This commit is contained in:
Shahin M. Shahin
2023-11-17 18:25:50 +03:00
committed by Disservin
parent 36db936e76
commit 282e15bf75
3 changed files with 36 additions and 19 deletions

View File

@@ -356,9 +356,9 @@ std::string UCI::value(Value v) {
if (abs(v) < VALUE_TB_WIN_IN_MAX_PLY)
ss << "cp " << UCI::to_cp(v);
else if (abs(v) < VALUE_MATE_IN_MAX_PLY)
else if (abs(v) <= VALUE_TB)
{
const int ply = VALUE_MATE_IN_MAX_PLY - 1 - std::abs(v); // recompute ss->ply
const int ply = VALUE_TB - std::abs(v); // recompute ss->ply
ss << "cp " << (v > 0 ? 20000 - ply : -20000 + ply);
}
else