[build] Add cpp_extension.py and publicly link torch.so

Summary:

Test Plan:

Reviewers:

Subscribers:

Tasks:

Tags:

ghstack-source-id: f246b0a
Pull Request resolved: #2183

Author: larryliu0820

CMakeLists.txt

@@ -416,7 +416,7 @@ if(EXECUTORCH_BUILD_PYBIND)
   target_include_directories(util PUBLIC ${_common_include_directories}
                                          ${TORCH_INCLUDE_DIRS})
   target_compile_options(util PUBLIC ${_pybind_compile_options})
-  target_link_libraries(util PRIVATE torch c10 executorch)
+  target_link_libraries(util PUBLIC torch c10 executorch)
 
   # pybind portable_lib
   pybind11_add_module(portable_lib extension/pybindings/pybindings.cpp)

extension/pybindings/cpp_extension.py

@@ -0,0 +1,51 @@
+from torch.utils import cpp_extension
+import os
+
+_HERE = os.path.abspath(__file__)
+_EXECUTORCH_PATH = os.path.dirname(os.path.dirname(_HERE))
+
+def load_inline(name,
+                cpp_sources,
+                functions=None,
+                extra_cflags=None,
+                extra_ldflags=None,
+                extra_include_paths=None,
+                build_directory=None,
+                verbose=False,
+                is_python_module=True,
+                with_pytorch_error_handling=True,
+                keep_intermediates=True,
+                use_pch=False):
+    # Register the code into PyTorch
+    aten_extra_cflags = ["-DUSE_ATEN_LIB"] + (extra_cflags if extra_cflags else [])
+    extra_ldflags = [f"-L{_EXECUTORCH_PATH}", f"-Wl,-rpath,{_EXECUTORCH_PATH}", "-lexecutorch"] + (extra_ldflags if extra_ldflags else [])
+    module = cpp_extension.load_inline(
+        name,
+        cpp_sources,
+        functions=functions,
+        extra_cflags=aten_extra_cflags,
+        extra_ldflags=extra_ldflags,
+        extra_include_paths=extra_include_paths,
+        build_directory=build_directory,
+        verbose=verbose,
+        is_python_module=is_python_module,
+        with_pytorch_error_handling=with_pytorch_error_handling,
+        keep_intermediates=keep_intermediates,
+        use_pch=use_pch,
+    )
+    # Now register the code into ExecuTorch
+    cpp_extension.load_inline(
+        name,
+        cpp_sources,
+        functions=None, # leave this out since we are not passing out any python module
+        extra_cflags=extra_cflags,
+        extra_ldflags=extra_ldflags,
+        extra_include_paths=extra_include_paths,
+        build_directory=build_directory,
+        verbose=verbose,
+        is_python_module=False, # don't register as a python module. Load shared library as a side effect.
+        with_pytorch_error_handling=with_pytorch_error_handling,
+        keep_intermediates=keep_intermediates,
+        use_pch=use_pch,
+    )
+    return module