CMake Quality of Life: export targets, ExternalProject #981
Description
Hi, I'm just starting to try out enzyme and it's a little bit unclear how to integrate it into an existing C++/CMake project.
After building and installing Enzyme, find_package does something, but I can't seem to figure out what it actually defines, or how to use it.
I was hoping that I might be able to follow the idiomatic cmake patterns of doing one of
- (installed Enzyme)
find_package(Enzyme REQUIRED)
add_executable(my_application main.cpp)
target_link_libraries(my_application PUBLIC Enzyme::Enzyme)- (Enzyme as a subdirectory)
add_subdirectory(path/to/Enzyme)
add_executable(my_application main.cpp)
target_link_libraries(my_application PUBLIC Enzyme::Enzyme)but neither seemed to work. I'm able to define a custom INTERFACE target locally, doing
add_library(Enzyme INTERFACE)
set(MY_ENZYME_LIB "/my/specific/hardcoded/path/to/Enzyme/enzyme/build/Enzyme/ClangEnzyme-14.so")
target_compile_options(Enzyme INTERFACE -flegacy-pass-manager)
target_compile_options(Enzyme INTERFACE "SHELL: -Xclang -load")
target_compile_options(Enzyme INTERFACE "SHELL: -Xclang ${MY_ENZYME_LIB}")
# note: the "SHELL: ..." stuff seems to be necessary to stop CMake's flag deduplication
# from removing the second -Xclang flag
add_executable(my_application main.cpp)
target_link_libraries(my_application PUBLIC Enzyme) # works!Would it make sense to include such a target in Enzyme directly, to streamline the user CMake experience?
Or maybe something like this already exists and I just missed it!
Another, unrelated thought: the documentation here seems a little out of date with respect to supported versions of LLVM. CMake's ExternalProject_Add tool would let the Enzyme CMake build grab a vetted version of the llvm repo and automatically configure/build it with the appropriate flags, which would make building from source as simple as
git clone https://github.com/EnzymeAD/Enzyme
cd Enzyme/enzyme
cmake . -Bbuild && cmake --build build --parallel
And for backward compatiiblity, if a user specified -DLLVM_DIR=... then the user-provided directory would be used instead of downloading LLVM through CMake.