CMake: Expose Python LTO Control

CHANGELOG.rst

@@ -25,6 +25,7 @@ Other
 
 - ADIOS2: require version 2.7.0+ #927
 - pybind11: require version 2.6.2+ #977
+- CMake: Expose Python LTO Control #980
 
 
 0.13.4

CMakeLists.txt

@@ -606,7 +606,25 @@ if(openPMD_HAVE_PYTHON)
         src/binding/python/UnitDimension.cpp
     )
     target_link_libraries(openPMD.py PRIVATE openPMD)
-    target_link_libraries(openPMD.py PRIVATE pybind11::module pybind11::lto pybind11::windows_extras)
+    target_link_libraries(openPMD.py PRIVATE pybind11::module pybind11::windows_extras)
+
+    # LTO/IPO: CMake target properties work well for 3.18+ and are buggy before
+    set(_USE_PY_LTO ON)  # default shall be ON
+    if(DEFINED CMAKE_INTERPROCEDURAL_OPTIMIZATION)  # overwrite default if defined
+        if(NOT CMAKE_INTERPROCEDURAL_OPTIMIZATION)
+            set(_USE_PY_LTO OFF)
+        endif()
+    endif()
+    message(STATUS "Python LTO/IPO: ${_USE_PY_LTO}")
+    if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.18)
+        set_target_properties(openPMD.py PROPERTIES
+            INTERPROCEDURAL_OPTIMIZATION ${_USE_PY_LTO})
+    else()
+        if(_USE_PY_LTO)
+            target_link_libraries(openPMD.py PRIVATE pybind11::lto)
+        endif()
+    endif()
+    unset(_USE_PY_LTO)
 
     pybind11_extension(openPMD.py)
     pybind11_strip(openPMD.py)

README.md

@@ -205,6 +205,13 @@ python3 -m pip install -U cmake
 openPMD_USE_MPI=ON python3 -m pip install openpmd-api --no-binary openpmd-api
 ```
 
+For some exotic architectures and compilers, you might need to disable a compiler feature called [link-time/interprocedural optimization](https://en.wikipedia.org/wiki/Interprocedural_optimization) if you encounter linking problems:
+```bash
+export CMAKE_INTERPROCEDURAL_OPTIMIZATION=OFF
+# optional:                                                --user
+python3 -m pip install openpmd-api --no-binary openpmd-api
+```
+
 ### From Source
 
 [![Source Use Case](https://img.shields.io/badge/use_case-development-brightgreen)](https://cmake.org)

docs/source/install/install.rst

@@ -107,6 +107,14 @@ If MPI-support shall be enabled, we always have to recompile:
    # optional:                                                                   --user
    openPMD_USE_MPI=ON python3 -m pip install openpmd-api --no-binary openpmd-api
 
+For some exotic architectures and compilers, you might need to disable a compiler feature called `link-time/interprocedural optimization <https://en.wikipedia.org/wiki/Interprocedural_optimization>`_ if you encounter linking problems:
+
+.. code-block:: bash
+
+   export CMAKE_INTERPROCEDURAL_OPTIMIZATION=OFF
+   # optional:                                                --user
+   python3 -m pip install openpmd-api --no-binary openpmd-api
+
 .. _install-cmake:
 
 .. only:: html

setup.py

@@ -69,6 +69,9 @@ def build_extension(self, ext):
             # Windows: has no RPath concept, all `.dll`s must be in %PATH%
             #          or same dir as calling executable
         ]
+        if CMAKE_INTERPROCEDURAL_OPTIMIZATION is not None:
+            cmake_args.append('-DCMAKE_INTERPROCEDURAL_OPTIMIZATION=' +
+                              CMAKE_INTERPROCEDURAL_OPTIMIZATION)
         if sys.platform == "darwin":
             cmake_args.append('-DCMAKE_INSTALL_RPATH=@loader_path')
         else:
@@ -133,6 +136,8 @@ def build_extension(self, ext):
                                BUILD_TESTING)
 BUILD_EXAMPLES = os.environ.get('openPMD_BUILD_EXAMPLES',
                                 BUILD_EXAMPLES)
+CMAKE_INTERPROCEDURAL_OPTIMIZATION = os.environ.get(
+    'CMAKE_INTERPROCEDURAL_OPTIMIZATION', None)
 
 # https://cmake.org/cmake/help/v3.0/command/if.html
 if openPMD_USE_MPI.upper() in ['1', 'ON', 'TRUE', 'YES']: