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Some more work on FullThreats::make_index

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[Passed STC](https://tests.stockfishchess.org/tests/live_elo/691fc321acb6dbdf23d07e4b):

```
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 215360 W: 55651 L: 55108 D: 104601
Ptnml(0-2): 520, 22399, 61290, 22960, 511
```

This PR is on top of ces42's work so I'll rebase if that PR changes.
Essentially, it comprises my adjustments to `make_index` that remained
unmerged before threat inputs was finalized.

The unsigned intermediate variables let us skip a bunch of useless sign
extensions (because Square and Piece inherit from `int8_t`, and C/C++
semantics require narrow integers to be promoted to `int` before doing
arithmetic on them). Additionally, by removing the special usage of
`offsets[][64]` and `[65]` the indexing becomes more efficient. (This
usage was a temporary hack from sscg anyway, so I think he'll like that
it's gone.) Finally, the `sf_assume` condition was fixed so that it
actually makes a difference to the compiler.

The speedup is fairly nice locally (combining both ces42's and these changes):

```
Result of 100 runs
==================
base (...kfish.master) =    1691982  +/- 1907
test (./stockfish    ) =    1714349  +/- 1789
diff                   =     +22367  +/- 2465

speedup        = +0.0132
P(speedup > 0) =  1.0000
```

closes https://github.com/official-stockfish/Stockfish/pull/6445

No functional change
This commit is contained in:
Carlos Esparza
2025-11-30 21:45:14 +01:00
committed by Disservin
parent 93f2d14d95
commit f4244e13e4
3 changed files with 31 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/types.h
+2 -6
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@@ -295,18 +295,14 @@ struct DirtyPiece {
struct DirtyThreat {
DirtyThreat() { /* don't initialize data */ }
DirtyThreat(Piece pc, Piece threatened_pc, Square pc_sq, Square threatened_sq, bool add) {
data = (add << 28) | (pc << 20) | (threatened_pc << 16) | (threatened_sq << 8) | (pc_sq);
data = (add << 31) | (pc << 20) | (threatened_pc << 16) | (threatened_sq << 8) | (pc_sq);
}
Piece pc() const { return static_cast<Piece>(data >> 20 & 0xf); }
Piece threatened_pc() const { return static_cast<Piece>(data >> 16 & 0xf); }
Square threatened_sq() const { return static_cast<Square>(data >> 8 & 0xff); }
Square pc_sq() const { return static_cast<Square>(data & 0xff); }
bool add() const {
uint32_t b = data >> 28;
sf_assume(b == 0 || b == 1);
return b;
}
bool add() const { return data >> 31; }
private:
uint32_t data;