Refactor MLIR python extension CMake boilerplate in a reusable function (NFC)

[stellaraccident]

Thanks.

mlir/cmake/modules/AddMLIRPythonExtension.cmake

87

This comment is stale and refers to the linker script that was removed.

mlir/cmake/modules/AddMLIRPythonExtension.cmake

+################################################################################
+# Build python extension
+################################################################################
+function(add_mlir_python_extension libname extname)
+  cmake_parse_arguments(ARG
+  ""
+  "INSTALL_DIR"
+  "SOURCES;LINK_LIBS"
+  ${ARGN})
+  if (ARG_UNPARSED_ARGUMENTS)
+    message(FATAL_ERROR " Unhandled arguments to add_mlir_python_extension(${libname}, ... : ${ARG_UNPARSED_ARGUMENTS}")
+  endif()
+  if ("${ARG_SOURCES}" STREQUAL "")
+    message(FATAL_ERROR " Missing SOURCES argument to add_mlir_python_extension(${libname}, ...")
+  endif()
+  if(NOT LLVM_BUILD_LLVM_DYLIB)
+    message(FATAL_ERROR "Building MLIR Python extension require -DLLVM_BUILD_LLVM_DYLIB=ON")
+  endif()
+
+  # Normally on unix-like platforms, extensions are built as "MODULE" libraries
+  # and do not explicitly link to the python shared object. This allows for
+  # some greater deployment flexibility since the extension will bind to
+  # symbols in the python interpreter on load. However, it also keeps the
+  # linker from erroring on undefined symbols, leaving this to (usually obtuse)
+  # runtime errors. Building in "SHARED" mode with an explicit link to the
+  # python libraries allows us to build with the expectation of no undefined
+  # symbols, which is better for development. Note that not all python
+  # configurations provide build-time libraries to link against, in which
+  # case, we fall back to MODULE linking.
+  if(PYTHON_LIBRARIES STREQUAL "" OR NOT MLIR_PYTHON_BINDINGS_VERSION_LOCKED)
+    set(PYEXT_LINK_MODE MODULE)
+    set(PYEXT_LIBADD)
+  else()
+    set(PYEXT_LINK_MODE SHARED)
+    set(PYEXT_LIBADD ${PYTHON_LIBRARIES})
+  endif()
+
+  # The actual extension library produces a shared-object or DLL and has
+  # sources that must be compiled in accordance with pybind11 needs (RTTI and
+  # exceptions).
+  add_library(${libname} ${PYEXT_LINK_MODE}
+    ${ARG_SOURCES}
+  )
+
+  target_include_directories(${libname} PRIVATE
+    "${PYTHON_INCLUDE_DIRS}"
+    "${pybind11_INCLUDE_DIRS}"
+  )
+
+  # The extension itself must be compiled with RTTI and exceptions enabled.
+  # Also, some warning classes triggered by pybind11 are disabled.
+  target_compile_options(${libname} PRIVATE
+    $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>,$<CXX_COMPILER_ID:GNU>>:
+      # Enable RTTI and exceptions.
+      -frtti -fexceptions
+      # Noisy pybind warnings
+      -Wno-unused-value
+      -Wno-covered-switch-default
+    >
+    $<$<CXX_COMPILER_ID:MSVC>:
+      # Enable RTTI and exceptions.
+      /EHsc /GR>
+  )
+
+  # Configure the output to match python expectations.
+  set_target_properties(
+    ${libname} PROPERTIES
+    # Build-time RPath layouts require to be a directory one up from the
+    # binary root.
+    # TODO: Don't reference the LLVM_BINARY_DIR here: the invariant is that
+    # the output directory must be at the same level of the lib directory
+    # where libMLIR.so is installed. This is presently not optimal from a
+    # project separation perspective and a discussion on how to better
+    # segment MLIR libraries needs to happen.
+    LIBRARY_OUTPUT_DIRECTORY ${LLVM_BINARY_DIR}/python
+    OUTPUT_NAME "_mlirTransforms"
+    PREFIX "${PYTHON_MODULE_PREFIX}"
+    SUFFIX "${PYTHON_MODULE_SUFFIX}${PYTHON_MODULE_EXTENSION}"
+  )
+
+  # pybind11 requires binding code to be compiled with -fvisibility=hidden
+  # For static linkage, better code can be generated if the entire project
+  # compiles that way, but that is not enforced here. Instead, include a linker
+  # script that explicitly hides anything but the PyInit_* symbols, allowing gc
+  # to take place.
+  set_target_properties(${libname} PROPERTIES CXX_VISIBILITY_PRESET "hidden")
+
+  target_link_libraries(${libname}
+    PRIVATE
+    MLIR # Always link to libMLIR.so
+    ${ARG_LINK_LIBS}
+    ${PYEXT_LIBADD}
+  )
+
+  llvm_setup_rpath(${libname})
+
+  ################################################################################
+  # Install
+  ################################################################################
+  if (INSTALL_DIR)
+    install(TARGETS ${libname}
+      COMPONENT ${libname}
+      LIBRARY DESTINATION ${ARG_INSTALL_DIR}
+      ARCHIVE DESTINATION ${ARG_INSTALL_DIR}
+      # NOTE: Even on DLL-platforms, extensions go in the lib directory tree.
+      RUNTIME DESTINATION ${ARG_INSTALL_DIR}
+    )
+  endif()
+
+  if (NOT LLVM_ENABLE_IDE)
+    add_llvm_install_targets(
+      install-${libname}
+      DEPENDS ${libname}
+      COMPONENT ${libname})
+  endif()
+
+endfunction()

mlir/lib/Bindings/Python/CMakeLists.txt

 if(NOT LLVM_BUILD_LLVM_DYLIB)
   message(FATAL_ERROR "Building the MLIR Python bindings require -DLLVM_BUILD_LLVM_DYLIB=ON")
 endif()
 
+include(AddMLIRPythonExtension)
+
 ################################################################################
 # Copy python source tree.
 ################################################################################
 
 set(PY_SRC_FILES
   mlir/__init__.py
   mlir/ir.py
   mlir/dialects/__init__.py
add_custom_command(
     COMMENT "Copying python source ${PY_SRC_FILE} -> ${PY_DEST_FILE}"
     DEPENDS "${PY_SRC_FILE}"
     COMMAND "${CMAKE_COMMAND}" -E copy_if_different
         "${CMAKE_CURRENT_SOURCE_DIR}/${PY_SRC_FILE}" "${PY_DEST_FILE}"
   )
 endforeach()
 
 ################################################################################
-# Build python extension
+# Build core python extension
 ################################################################################
-
-# Normally on unix-like platforms, extensions are built as "MODULE" libraries
-# and do not explicitly link to the python shared object. This allows for
-# some greater deployment flexibility since the extension will bind to
-# symbols in the python interpreter on load. However, it also keeps the
-# linker from erroring on undefined symbols, leaving this to (usually obtuse)
-# runtime errors. Building in "SHARED" mode with an explicit link to the
-# python libraries allows us to build with the expectation of no undefined
-# symbols, which is better for development. Note that not all python
-# configurations provide build-time libraries to link against, in which
-# case, we fall back to MODULE linking.
-if(PYTHON_LIBRARIES STREQUAL "" OR NOT MLIR_PYTHON_BINDINGS_VERSION_LOCKED)
-  set(PYEXT_LINK_MODE MODULE)
-  set(PYEXT_LIBADD)
-else()
-  set(PYEXT_LINK_MODE SHARED)
-  set(PYEXT_LIBADD ${PYTHON_LIBRARIES})
-endif()
-
-# The actual extension library produces a shared-object or DLL and has
-# sources that must be compiled in accordance with pybind11 needs (RTTI and
-# exceptions).
-# TODO: Link the libraries separately once a helper function is available
-# to more generically add a pybind11 compliant library.
-add_library(MLIRBindingsPythonExtension ${PYEXT_LINK_MODE}
+add_mlir_python_extension(MLIRBindingsPythonExtension _mlir
+  INSTALL_DIR
+    python
+  SOURCES
     MainModule.cpp
     IRModules.cpp
+    Pass.cpp
     PybindUtils.cpp
 )
-
-target_include_directories(MLIRBindingsPythonExtension PRIVATE
-  "${PYTHON_INCLUDE_DIRS}"
-  "${pybind11_INCLUDE_DIRS}")
-
-# The extension itself must be compiled with RTTI and exceptions enabled.
-# Also, some warning classes triggered by pybind11 are disabled.
-target_compile_options(MLIRBindingsPythonExtension PRIVATE
-  $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>,$<CXX_COMPILER_ID:GNU>>:
-    # Enable RTTI and exceptions.
-    -frtti -fexceptions
-    # Noisy pybind warnings
-    -Wno-unused-value
-    -Wno-covered-switch-default
-  >
-  $<$<CXX_COMPILER_ID:MSVC>:
-    # Enable RTTI and exceptions.
-    /EHsc /GR>
-)
-
-# Configure the output to match python expectations.
-set_target_properties(
-  MLIRBindingsPythonExtension PROPERTIES
-    # Build-time RPath layouts require to be a directory one up from the
-    # binary root.
-    # TODO: Don't reference the LLVM_BINARY_DIR here: the invariant is that
-    # the output directory must be at the same level of the lib directory
-    # where libMLIR.so is installed. This is presently not optimal from a
-    # project separation perspective and a discussion on how to better
-    # segment MLIR libraries needs to happen.
-    LIBRARY_OUTPUT_DIRECTORY ${LLVM_BINARY_DIR}/python
-    OUTPUT_NAME "_mlir"
-    PREFIX "${PYTHON_MODULE_PREFIX}"
-    SUFFIX "${PYTHON_MODULE_SUFFIX}${PYTHON_MODULE_EXTENSION}"
-)
-
-# pybind11 requires binding code to be compiled with -fvisibility=hidden
-# For static linkage, better code can be generated if the entire project
-# compiles that way, but that is not enforced here. Instead, include a linker
-# script that explicitly hides anything but the PyInit_* symbols, allowing gc
-# to take place.
-# TODO: Add a Windows .def file and figure out the right thing to do on MacOS.
-set_target_properties(
-  MLIRBindingsPythonExtension PROPERTIES CXX_VISIBILITY_PRESET "hidden")
-
-set(PYEXT_DEPS)
-list(APPEND PYEXT_DEPS
-  # Depend on libMLIR.so first so that deps primarily come from the shared
-  # library.
-  MLIR
-)
-
-target_link_libraries(MLIRBindingsPythonExtension
-  PRIVATE
-  ${PYEXT_DEPS}
-  ${PYEXT_LIBADD}
-)
-
 add_dependencies(MLIRBindingsPythonExtension MLIRBindingsPythonSources)
-llvm_setup_rpath(MLIRBindingsPythonExtension)
-
-################################################################################
-# Install
-################################################################################
-
-install(TARGETS MLIRBindingsPythonExtension
-  COMPONENT MLIRBindingsPythonExtension
-  LIBRARY DESTINATION python
-  ARCHIVE DESTINATION python
-  # NOTE: Even on DLL-platforms, extensions go in the lib directory tree.
-  RUNTIME DESTINATION python)
 
 # Note that we copy from the source tree just like for headers because
 # it will not be polluted with py_cache runtime artifacts (from testing and
 # such).
 install(
   DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/mlir
   DESTINATION python
   COMPONENT MLIRBindingsPythonSources
   FILES_MATCHING PATTERN "*.py"
 )
 
 if (NOT LLVM_ENABLE_IDE)
   add_llvm_install_targets(
-    install-MLIRBindingsPythonExtension
-    DEPENDS MLIRBindingsPythonExtension
-    COMPONENT MLIRBindingsPythonExtension)
-  add_llvm_install_targets(
     install-MLIRBindingsPythonSources
     DEPENDS MLIRBindingsPythonSources
     COMPONENT MLIRBindingsPythonSources)
 endif()