Compilation using Visual Studio 2022

[sascha-holl]

Did anybody successfully built clad on Windows? I'm failing to do so, since a couple of days now. I'm using LLVM 18.1.0, which I also built form source. When I do not add LLVM_ENABLE_PLUGINS and LLVM_EXPORT_SYMBOLS_FOR_PLUGINS for the LLVM compilation and compile clad with STATI, then compilation succeeds. However, I cannot execute any program without getting the console output "clad failed to place the generated derivative in the object. Make sure calls to clad are within a #pragma clad ON region."

So I thought the reason is that I need to "attach" the clad plugin to the clang compiler. But currently no DLL is generated. I only got a "cladPlugin.lib" and "cladDifferentiator.lib". So, I guess I need to add LLVM_ENABLE_PLUGINS and LLVM_EXPORT_SYMBOLS_FOR_PLUGINS. However, 2 projects fail then (due to DLL symbol export limit of 65535).

Is there any instruction how to use clad on Windows?

[vgvassilev]

Hi @de-sholl, Clang plugins are not supported on Windows, yet. @fsfod is actively working on this you can take a look at his recent work in llvm/llvm-project#96630. I hope in llvm 19 he succeeds to make LLVM_ENABLE_PLUGINS work for Windows.

That being said, Clad works on Windows in the ROOT project. The trick is to build clang and statically link cladPlugin.lib and cladDifferentiator.lib to the clang binary.

[vgvassilev]

This is the relevant commit I had in mind: root-project/root@f2273e0

We need to tell the linker to paste the whole static archive in the binary.

[sascha-holl]

What is your suggestion? Currently I'm working with the generated clang.sln. I thought "Link Library Dependencies" or "Use Library Dependency Inputs" might exactly do what you described; pasting the whole static archive into the binary.

Do you suggest to work with cmake instead? I've added the following to Clang -> CmakeLists.txt:

set(CLANG_PLUGIN_LINK_LIBS cladPlugin cladDifferentiator)
set(CLAD_LIBS "-WHOLEARCHIVE:cladPlugin.lib -WHOLEARCHIVE:cladDifferentiator.lib")
add_dependencies(clang clad)
target_link_libraries(clang PUBLIC ${CLANG_PLUGIN_LINK_LIBS})

[vgvassilev]

Yeah, maybe that would work. The sln file is generated by cmake. That should probably do.

[sascha-holl]

It finally works! I had to add /WHOLEARCHIVE:cladPlugin.lib /WHOLEARCHIVE:cladDifferentiator.lib to Linker -> Command Line -> Additional Options in the clang.sln. Now compilation and also execution of the BasicUsage examples works without an error.

Thank you very much for your help along!