chunk tinygrad pkl below GitHub max size - NoCache and AlwaysBuild (#37194)

* nocache

* +

* fixes

* lint

* not split

* use pathlib

* cleanup

* better

* even better

selfdrive/modeld/SConscript

@@ -3,6 +3,7 @@ import glob
 
 Import('env', 'arch')
 lenv = env.Clone()
+CHUNK_BYTES = int(os.environ.get("TG_CHUNK_BYTES", str(45 * 1024 * 1024)))
 
 tinygrad_root = env.Dir("#").abspath
 tinygrad_files = ["#"+x for x in glob.glob(env.Dir("#tinygrad_repo").relpath + "/**", recursive=True, root_dir=tinygrad_root)
@@ -36,12 +37,28 @@ lenv.Command(warp_targets, tinygrad_files + script_files, cmd)
 def tg_compile(flags, model_name):
   pythonpath_string = 'PYTHONPATH="${PYTHONPATH}:' + env.Dir("#tinygrad_repo").abspath + '"'
   fn = File(f"models/{model_name}").abspath
-  return lenv.Command(
-    fn + "_tinygrad.pkl",
+
+  out = fn + "_tinygrad.pkl"
+  full = out + ".full"
+  parts = out + ".parts"
+
+  full_node = lenv.Command(
+    full,
     [fn + ".onnx"] + tinygrad_files,
-    f'{pythonpath_string} {flags} {image_flag} python3 {Dir("#tinygrad_repo").abspath}/examples/openpilot/compile3.py {fn}.onnx {fn}_tinygrad.pkl'
+    f'{pythonpath_string} {flags} {image_flag} python3 {Dir("#tinygrad_repo").abspath}/examples/openpilot/compile3.py {fn}.onnx {full}'
   )
 
+  split_script = File(Dir("#selfdrive/modeld").File("external_pickle.py").abspath)
+  parts_node = lenv.Command(
+    parts,
+    [full_node, split_script, Value(str(CHUNK_BYTES))],
+    [f'python3 {split_script.abspath} {full} {out} {CHUNK_BYTES}', Delete(full)],
+  )
+
+  lenv.NoCache(parts_node)
+  lenv.AlwaysBuild(parts_node)
+  return parts_node
+
 # Compile small models
 for model_name in ['driving_vision', 'driving_policy', 'dmonitoring_model']:
   tg_compile(tg_flags, model_name)