[xnnpack] Add debug XNNGraph printing (#7617)

Prints to a file, with increasing id.
TODO: use actual delegate instance id in the filename. Take filepath from
compile_spec.

Author: digantdesai

backends/xnnpack/serialization/xnnpack_graph_serialize.py

@@ -5,18 +5,23 @@
 # LICENSE file in the root directory of this source tree.
 
 import json
+
+import logging
 import os
 import tempfile
 
 from dataclasses import dataclass, fields, is_dataclass
-from typing import ClassVar, Literal
+from typing import ClassVar, Literal, Optional
 
 import pkg_resources
 from executorch.backends.xnnpack.serialization.xnnpack_graph_schema import XNNGraph
 from executorch.exir._serialize._dataclass import _DataclassEncoder
 
 from executorch.exir._serialize._flatbuffer import _flatc_compile
 
+logger = logging.getLogger(__name__)
+logger.setLevel(logging.WARNING)
+
 # Byte order of numbers written to program headers. Always little-endian
 # regardless of the host system, since all commonly-used modern CPUs are little
 # endian.
@@ -273,19 +278,42 @@ def _pad_to(data: bytes, length: int) -> bytes:
     return data
 
 
-def pretty_print_xnngraph(xnnpack_graph_json: str):
+def pretty_print_xnngraph(xnnpack_graph_json: str, filename: Optional[str] = None):
     """
-    Pretty print the XNNGraph
+    Pretty print the XNNGraph, optionally writing to a file if filename is provided
     """
-    from pprint import pprint
+    from pprint import pformat
 
     d = json.loads(xnnpack_graph_json)
-    pprint(d)
+    pstr = pformat(d, indent=2, compact=True).replace("'", '"')
+    if filename:
+        with open(filename, "w") as f:
+            if filename.endswith(".json"):
+                pstr = pstr.replace("None", "null")
+            f.write(pstr)
+    else:  # dump to stdout
+        print("XNNGraph:")
+        print(pstr)
+        print("End of XNNGraph")
+
+
+# TODO: Replace this with an actual delegate id
+_delegate_instance_id = 0
 
 
 def convert_to_flatbuffer(xnnpack_graph: XNNGraph) -> bytes:
+    global _delegate_instance_id
     sanity_check_xnngraph_dataclass(xnnpack_graph)
     xnnpack_graph_json = json.dumps(xnnpack_graph, cls=_DataclassEncoder)
+
+    # Log the XNNGraph if debugging
+    if logger.getEffectiveLevel() == logging.DEBUG:
+        filename: str = f"./xnnpack_delegate_graph_{_delegate_instance_id}.json"
+        logger.debug(f"Writing XNNGraph to {filename}")
+        pretty_print_xnngraph(xnnpack_graph_json, filename)
+
+    _delegate_instance_id += 1
+
     with tempfile.TemporaryDirectory() as d:
         schema_path = os.path.join(d, "schema.fbs")
         with open(schema_path, "wb") as schema_file: