[WIP] Fix OpenMP on Windows

[ax3l]

Working on AMReX-Codes/amrex#3795

• run OpenMP tests
• try Workaround for Windows omp_lock_t issue AMReX-Codes/amrex#3910

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[ax3l]

So strange that the OpenMP tests pass here:

...
    llvm-openmp:     18.1.3-h91493d7_0         conda-forge
...
-- Found OpenMP_CXX: -Xclang -fopenmp (found version "5.1")
-- Found OpenMP: TRUE (found version "5.1") found components: CXX
...
--    C++ compiler             = D:/bld/amrex_1714368890030/_build_env/Library/bin/clang-cl.exe
--    C++ flags                = /O2 /Ob2 /DNDEBUG /DWIN32 /D_WINDOWS /GR /EHsc -Xclang -fopenmp
--    Link line                = D:/bld/amrex_1714368890030/_h_env/Library/lib/libomp.lib
...
[599/601] C:\Windows\system32\cmd.exe /C "cd . && %BUILD_PREFIX%\Library\bin\cmake.exe -E vs_link_exe --intdir=Tests\OpenMP\atomicAdd\CMakeFiles\Test_OpenMP_atomicAdd_1d.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100226~1.0\x64\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\100226~1.0\x64\mt.exe --manifests  -- %BUILD_PREFIX%\Library\bin\lld-link.exe  Tests\OpenMP\atomicAdd\CMakeFiles\Test_OpenMP_atomicAdd_1d.dir\main.cpp.obj  /out:Tests\OpenMP\atomicAdd\1d\Test_OpenMP_atomicAdd_1d.exe /implib:Tests\OpenMP\atomicAdd\Test_OpenMP_atomicAdd_1d.lib /pdb:Tests\OpenMP\atomicAdd\1d\Test_OpenMP_atomicAdd_1d.pdb /version:0.0 /machine:x64 /INCREMENTAL:NO /subsystem:console  Src\amrex_1d.lib  %PREFIX%\Library\lib\libomp.lib  kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."
...
(%BUILD_PREFIX%) %SRC_DIR%>ctest --test-dir build --build-config Release --output-on-failure -R OpenMP 
Internal ctest changing into directory: D:/bld/amrex_1714368890030/work/build
Test project D:/bld/amrex_1714368890030/work/build
    Start 105: OpenMP_atomicAdd_1d
1/3 Test #105: OpenMP_atomicAdd_1d ..............   Passed    0.06 sec
    Start 106: OpenMP_atomicAdd_2d
2/3 Test #106: OpenMP_atomicAdd_2d ..............   Passed    0.03 sec
    Start 107: OpenMP_atomicAdd_3d
3/3 Test #107: OpenMP_atomicAdd_3d ..............   Passed    0.08 sec

100% tests passed, 0 tests failed out of 3

Total Test time (real) =   0.23 sec
...
   INFO (amrex,Library/bin/amrex_3d.dll): Needed DSO Library/bin/libomp.dll found in conda-forge/win-64::llvm-openmp==18.1.3=h91493d7_0
   INFO (amrex,Library/bin/amrex_1d.dll): Needed DSO Library/bin/libomp.dll found in conda-forge/win-64::llvm-openmp==18.1.3=h91493d7_0
   INFO (amrex,Library/bin/amrex_2d.dll): Needed DSO Library/bin/libomp.dll found in conda-forge/win-64::llvm-openmp==18.1.3=h91493d7_0
...

but not in a dependent repo (WarpX/ImpactX) anymore.

[ax3l]

@isuruf I am installing the AMReX import libs amrex_*.lib into lib/ while installing the dynamic symbols amrex_*.dll into bin/ ... is that a problem? (I think it has not caused issues in the past and should not have changed a few months ago...)

2024-04-29T06:01:10.1934787Z -- Installing: D:/bld/amrex_1714368890030/_h_env/Library/lib/amrex_3d.lib
2024-04-29T06:01:10.2011064Z -- Installing: D:/bld/amrex_1714368890030/_h_env/Library/bin/amrex_3d.dll

https://gitlab.kitware.com/cmake/community/-/wikis/FAQ#why-does-find_library-not-find-dll-libraries-under-win32

The downstream link line is currently:

2024-04-29T06:28:05.2920628Z LINK: command "%BUILD_PREFIX%\Library\bin\lld-link.exe CMakeFiles\app.dir\src\main.cpp.obj /out:bin\impactx.NOMPI.OMP.DP.OPMD.exe /implib:lib\impactx.NOMPI.OMP.DP.OPMD.lib /pdb:bin\impactx.NOMPI.OMP.DP.OPMD.pdb /version:0.0 /machine:x64 /INCREMENTAL:NO /subsystem:console lib\libimpactx.NOMPI.OMP.DP.OPMD.lib lib\buildInfopyImpactX.lib lib\ablastr_3d.lib %PREFIX%\Library\lib\amrex_3d.lib %PREFIX%\Library\lib\libomp.lib %PREFIX%\Library\lib\openPMD.lib %PREFIX%\Library\lib\adios2_cxx11.lib %PREFIX%\Library\lib\openPMD.lib %PREFIX%\Library\lib\adios2_cxx11.lib kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST:EMBED,ID=1" failed (exit code 1) with the following output:
2024-04-29T06:28:05.2922201Z lld-link: error: undefined symbol: struct omp_lock_t * __cdecl amrex::OpenMP::get_lock(int)
2024-04-29T06:28:06.3576700Z >>> referenced by libimpactx.NOMPI.OMP.DP.OPMD.lib(ChargeDeposition.cpp.obj):(public: class amrex::BaseFab<double> & __cdecl amrex::BaseFab<double>::lockAdd<1>(class amrex::BaseFab<double> const &, class amrex::Box const &, class amrex::Box const &, int, int, int))

[isuruf]

I am installing the AMReX import libs amrex_.lib into lib/ while installing the dynamic symbols amrex_.dll into bin/ ... is that a problem?

Nope

[ax3l]

I noticed that I cannot find a symbol for omp_lock_t in neither libiomp5md.dll nor libomp.dll of the conda-forge llvm-openmp package... (using radare2's rabin2 -s ...) But somehow, I generally only see function symbols...

[isuruf]

Types don't have symbols in dynamic libraries. Only functions and global data variables.

[ax3l]

I'll try patching in AMReX-Codes/amrex#3910 to the 24.05 release.

[ax3l]

In parallel, I contributed to CMake 3.30+ the support for OpenMP from LLVM in MSVC (instead of LLVM-OpenMP w/ Clang-Cl, which we currently use on Conda-Forge -- or the OpenMP 2.0 that comes with MSVC by default, which we cannot use because it is too old):
https://gitlab.kitware.com/cmake/cmake/-/merge_requests/9475

Thus, we can try to compile on Conda-Forge with MSVC on Windows again using the new LLVM OpenMP support once that CMake release is out.

[ax3l]

Testing the patch for the 24.05 release via #24

[ax3l]

Patch in upstream for 24.05+