Build pybindings and link in backends when building pip wheels

Always build the pybindings when building the pip wheel.

Always link in XNNPACK.

On macos, also link in MPS. Core ML can't build on the worker machine,
though, because the version of macOS is too old; Core ML requires some
features introduced in macOS 10.15.

Author: dbort

.github/workflows/build-wheels-linux.yml

@@ -54,6 +54,7 @@ jobs:
       # "recursive" default to do less work, and to give the buck daemon fewer
       # files to look at.
       submodules: true
+      env-var-script: build/packaging/env_var_script_linux.sh
       pre-script: ${{ matrix.pre-script }}
       post-script: ${{ matrix.post-script }}
       package-name: ${{ matrix.package-name }}

.github/workflows/build-wheels-m1.yml

@@ -54,6 +54,7 @@ jobs:
       # "recursive" default to do less work, and to give the buck daemon fewer
       # files to look at.
       submodules: true
+      env-var-script: build/packaging/env_var_script_m1.sh
       pre-script: ${{ matrix.pre-script }}
       post-script: ${{ matrix.post-script }}
       package-name: ${{ matrix.package-name }}

build/packaging/env_var_script_linux.sh

@@ -0,0 +1,20 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# This file is sourced into the environment before building a pip wheel. It
+# should typically only contain shell variable assignments. Be sure to export
+# any variables so that subprocesses will see them.
+
+# Enable pybindings so that users can execute ExecuTorch programs from python.
+export EXECUTORCH_BUILD_PYBIND=1
+
+# Ensure that CMAKE_ARGS is defined before referencing it. Defaults to empty
+# if not defined.
+export CMAKE_ARGS="${CMAKE_ARGS:-}"
+
+# Link the XNNPACK backend into the pybindings runtime so that users can execute
+# ExecuTorch programs that delegate to it.
+CMAKE_ARGS="${CMAKE_ARGS} -DEXECUTORCH_BUILD_XNNPACK=ON"

build/packaging/env_var_script_m1.sh

@@ -0,0 +1,28 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# This file is sourced into the environment before building a pip wheel. It
+# should typically only contain shell variable assignments. Be sure to export
+# any variables so that subprocesses will see them.
+
+# Enable pybindings so that users can execute ExecuTorch programs from python.
+export EXECUTORCH_BUILD_PYBIND=1
+
+# Ensure that CMAKE_ARGS is defined before referencing it. Defaults to empty
+# if not defined.
+export CMAKE_ARGS="${CMAKE_ARGS:-}"
+
+# Link the XNNPACK backend into the pybindings runtime so that users can execute
+# ExecuTorch programs that delegate to it.
+CMAKE_ARGS="${CMAKE_ARGS} -DEXECUTORCH_BUILD_XNNPACK=ON"
+
+# When building for macOS, link additional backends into the pybindings runtime.
+
+# TODO(dbort): Core ML requires features only available in macOS 10.15, but the
+# build machine uses an older version.
+# CMAKE_ARGS="${CMAKE_ARGS} -DEXECUTORCH_BUILD_COREML=ON"
+
+CMAKE_ARGS="${CMAKE_ARGS} -DEXECUTORCH_BUILD_MPS=ON"

setup.py

@@ -83,11 +83,6 @@ def _is_env_enabled(env_var: str, default: bool = False) -> bool:
     def pybindings(cls) -> bool:
         return cls._is_env_enabled("EXECUTORCH_BUILD_PYBIND", default=False)
 
-    @classmethod
-    @property
-    def xnnpack(cls) -> bool:
-        return cls._is_env_enabled("EXECUTORCH_BUILD_XNNPACK", default=False)
-
 
 class _BaseExtension(Extension):
     """A base class that maps an abstract source to an abstract destination."""
@@ -372,13 +367,9 @@ def run(self):
                 "-DEXECUTORCH_BUILD_PYBIND=ON",
             ]
             build_args += ["--target", "portable_lib"]
-            if ShouldBuild.xnnpack:
-                cmake_args += [
-                    "-DEXECUTORCH_BUILD_XNNPACK=ON",
-                ]
-                # No target needed; the cmake arg will link xnnpack
-                # into the portable_lib target.
-            # TODO(dbort): Add MPS/CoreML backends when building on macos.
+            # To link backends into the portable_lib target, callers should
+            # add entries like `-DEXECUTORCH_BUILD_XNNPACK=ON` to the CMAKE_ARGS
+            # environment variable.
 
         # Allow adding extra cmake args through the environment. Used by some
         # tests and demos to expand the set of targets included in the pip