Compress threat indexing, update feature set name to Full Threats v2

[sscg13]

This is the corresponding trainer side changes for official-stockfish/Stockfish#6635

[Disservin]

will need a rebase now that shawns pr is in

[vondele]

This fails for me..

$ numactl --cpunodebind=0 python -u train.py /workspace/data/vondele/from_kaggle_2/T60T70wIsRightFarseerT60T74T75T76.split_0.binpack /workspace/data/vondele/from_kaggle_2/T60T70wIsRightFarseerT60T74T75T76.split_1.binpack /workspace/data/vondele/from_kaggle_2/T60T70wIsRightFarseerT60T74T75T76.split_2.binpack /workspace/data/vondele/from_kaggle_2/T60T70wIsRightFarseerT60T74T75T76.split_3.binpack /workspace/data/vondele/from_kaggle_2/T60T70wIsRightFarseerT60T74T75T76.split_4.binpack /workspace/data/official-stockfish/master-binpacks/nodes5000pv2_UHO.binpack /workspace/data/official-stockfish/master-binpacks/wrongIsRight_nodes5000pv2.binpack /workspace/data/official-stockfish/master-binpacks/multinet_pv-2_diff-100_nodes-5000.binpack /workspace/data/official-stockfish/master-binpacks/dfrc_n5000.binpack --threads=4 --gpus=0,1,2,3, --num-workers=96 --batch-size=65536 --features=Full_Threatsv2^ --l1=1024 --lr=4.375e-4 --gamma=0.995 --start-lambda=1.0 --end-lambda=0.75 --random-fen-skipping=10 --early-fen-skipping=12 --pc-y1=0.6893201149773951 --pc-y2=2.9285769485515805 --pc-y3=1.4386005301749225 --w1=3.3553547771220007 --w2=0.7006821612968052  --max_epochs=4 --network-save-period=4 --default_root_dir /workspace/scratch/training/runs/run_8
batch_size(global)=65536 | n_devices=4 | batch_size(per_gpu)=16384
Traceback (most recent call last):
  File "/workspace/nnue-pytorch/train.py", line 280, in <module>
    main()
  File "/workspace/nnue-pytorch/train.py", line 154, in main
    feature_cls = M.get_feature_cls(args.features)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/workspace/nnue-pytorch/model/modules/features/__init__.py", line 28, in get_feature_cls
    raise KeyError(f"Unknown feature '{name}'. Available: {', '.join(_FEATURES)}")
KeyError: "Unknown feature 'Full_Threatsv2^'. Available: HalfKAv2_hm^, Full_Threats^"

A bit unclear why we call this v2, honestly, it is functionally equivalent to the previous version?

[Disservin]

halfkav2 was also identical to halfka except it used less space

[vondele]

Still needs a rebase and

diff --git a/model/modules/__init__.py b/model/modules/__init__.py
index e533443..4e3cec3 100644
--- a/model/modules/__init__.py
+++ b/model/modules/__init__.py
@@ -5,7 +5,7 @@ from .feature_transformer import (
 )
 from .features import (
     HalfKav2Hm,
-    FullThreats,
+    FullThreatsv2,
     get_feature_cls,
     get_available_features,
     add_feature_args,
@@ -18,7 +18,7 @@ __all__ = [
     "DoubleFeatureTransformer",
     "FeatureTransformer",
     "HalfKav2Hm",
-    "FullThreats",
+    "FullThreatsv2",
     "get_feature_cls",
     "get_available_features",
     "add_feature_args",
diff --git a/model/utils/serialize.py b/model/utils/serialize.py
index d4b2989..c128bbe 100644
--- a/model/utils/serialize.py
+++ b/model/utils/serialize.py
@@ -158,7 +158,7 @@ class NNUEWriter:
 
         # Weights stored as [num_features][outputs]
         self.write_tensor(bias.flatten().numpy(), ft_compression)
-        if isinstance(layer, FullThreats):
+        if isinstance(layer, FullThreatsv2):
             threat_weight = weight[: layer.NUM_THREAT_FEATURES].to(torch.int8)
             psq_weight = weight[layer.NUM_THREAT_FEATURES :]
             self.write_tensor(threat_weight.flatten().numpy())
@@ -306,7 +306,7 @@ class NNUEReader:
 
         bias = self.tensor(np.int16, [num_outputs - num_psqt_buckets])
         # weights stored as [num_features][outputs]
-        if isinstance(layer, FullThreats):
+        if isinstance(layer, FullThreatsv2):
             threat_weight = self.tensor(
                 np.int8, [layer.NUM_THREAT_FEATURES, num_outputs - num_psqt_buckets]
             )