Add graph PP infrastructure for autoparallel

stack-info: PR: #2726, branch: sanketpurandare/stack/5

Author: Sanket Jayant Purandare

torchtitan/experiments/autoparallel/configs.py

@@ -4,9 +4,12 @@
 # This source code is licensed under the BSD-style license found in the
 # LICENSE file in the root directory of this source tree.
 
-from dataclasses import dataclass, field
+from collections.abc import Callable
+from dataclasses import dataclass, field, fields
 
+from torchtitan.config import ActivationCheckpointConfig
 from torchtitan.config.configs import CompileConfig
+from torchtitan.protocols.model_spec import ModelSpec
 from torchtitan.trainer import Trainer
 
 
@@ -23,3 +26,30 @@ class AutoParallelConfig(Trainer.Config):
     compile: AutoParallelCompileConfig = field(
         default_factory=AutoParallelCompileConfig
     )
+
+
+def to_autoparallel_config(
+    base_config: Trainer.Config,
+    model_registry: Callable[[str], ModelSpec],
+    flavor: str | None = None,
+) -> AutoParallelConfig:
+    """Convert a base Trainer.Config to an AutoParallelConfig.
+
+    Copies all fields from the base config and replaces the model_spec with one
+    from the autoparallel model_registry. The compile field is removed and
+    left as the AutoParallelConfig default; callers should explicitly set it.
+
+    Args:
+        base_config: The base Trainer.Config to convert.
+        model_registry: A callable that returns a ModelSpec for a given flavor.
+        flavor: Optional flavor override. If None, uses the base config's flavor.
+    """
+    d = {f.name: getattr(base_config, f.name) for f in fields(base_config)}
+    d["model_spec"] = model_registry(flavor or base_config.model_spec.flavor)
+    d.pop("compile")
+
+    ac = d.get("activation_checkpoint")
+    if ac is not None and ac.mode != "none":
+        d["activation_checkpoint"] = ActivationCheckpointConfig(mode="selective")
+
+    return AutoParallelConfig(**d)