[GitHub] [tvm] cgerum commented on a diff in pull request #14165: [TVMC][UMA] Support using UMA with TVMC

["cgerum (via GitHub)" <gi...@apache.org>]

cgerum commented on code in PR #14165:
URL: https://github.com/apache/tvm/pull/14165#discussion_r1122917478


##########
python/tvm/driver/tvmc/extensions.py:
##########
@@ -0,0 +1,128 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""
+Allows to extend TVMC with external code.
+"""
+import sys
+import importlib
+import inspect
+import pkgutil
+import warnings
+import copy
+from abc import abstractmethod
+
+
+_EXTENSIONS = []
+
+
+class TVMExtension(object):

Review Comment:
   Just a minor nit, but is it TVMExtension or TVMCExtension



##########
python/tvm/driver/tvmc/extensions.py:
##########
@@ -0,0 +1,128 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""
+Allows to extend TVMC with external code.
+"""
+import sys
+import importlib
+import inspect
+import pkgutil
+import warnings
+import copy
+from abc import abstractmethod
+
+
+_EXTENSIONS = []
+
+
+class TVMExtension(object):
+    @abstractmethod
+    def uma_backends(self):
+        return []
+
+
+def get_extensions():
+    """Returns all loaded extensions."""
+
+    for ext in _EXTENSIONS:
+        yield ext
+
+
+def load_extensions(paths):
+    """
+    Loads extensions from the given locations.
+
+    Extensions must implement the `TVMExtension` interface and be stored in a directory called
+    `tvm_extension`.
+    """
+
+    path_backup = copy.copy(sys.path)
+    sys.path.extend(paths)
+
+    top_modules = []
+    try:
+        mod = importlib.import_module("tvm_extension")
+        top_modules.append(mod)
+    except ImportError:
+        pass
+
+    sys.path.clear()
+    sys.path.extend(path_backup)
+
+    extension_classes = _scan_all(top_modules)
+    for ext_cls in extension_classes:
+        _EXTENSIONS.append(ext_cls())
+
+
+def _scan_all(top_level):
+    scanned_extensions = []
+    for mdl in top_level:
+        for importer, modname, _ in pkgutil.walk_packages(
+            path=mdl.__path__, prefix=mdl.__name__ + ".", onerror=lambda x: None
+        ):
+            try:
+                module_name = modname.rsplit(".", 1)[-1]
+                # If module's name starts with "_", do not load the module.
+                # But if the module's name starts with a "__", then load the
+                # module.
+                if module_name.startswith("_") and not module_name.startswith("__"):
+                    continue

Review Comment:
   Not scanning in '_' allows to split interface and implementation:
   
   `my_backend.py`:
   
   ```
   class MyBackendExtension(TVMExtension):
       def __init__(self):
           from ._impl import MyBacken
           self.backend = MyBackend()
   
       def uma_backends(self):
           return [self.backend]
   ```
   
   
   `_my_backend_impl.py`:
   
   ```
   class MyBackend(UMABackend):
      ....
   ```
   
   The exception for "__" is there to allow declaring extensions in `__init__.py` and `__main__.py` but I am not sure wether this is actually worth it. Or we should just scan all modules for now. 



##########
python/tvm/relay/backend/contrib/uma/api/lower.py:
##########
@@ -71,9 +71,7 @@ def _get_tensors(te_cached_func):
         )
 
         compiler_attr = relay_prim_func.attrs["Compiler"]
-        target = tvm.target.Target.current()
-        if target.kind.name != compiler_attr:
-            target = tvm.target.Target(compiler_attr)
+        target = tvm.target.Target(compiler_attr)

Review Comment:
   I think `tvm.target.Target.current()` should generally work. The main reason for using ``target.Target.current()` is to allow the declaration of target specific options, e.G.: 
   
   ```
   target = tvm.target.Target("vanilla_backend --use-tuner=true --target-local-ram=10240")
   ```
   
   I would have assumed that `target.current` is always set in the compilation flow, but if it actually can be None, we can probabbly use: 
   
   ```
   if (target is None) or (target.kind.name != compiler_attr):
   ```
   



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