jdoerfert added a comment. In D143306#4145465 <https://reviews.llvm.org/D143306#4145465>, @MaskRay wrote:
> In D143306#4144541 <https://reviews.llvm.org/D143306#4144541>, @jdoerfert > wrote: > >> I'm worried this makes use of LLVM on HPC machines even harder. That said, >> I'm open to suggestions and I am not well versed in all the ways we can make >> it work. >> Our problem is that there are N `libomptarget.so` files and N >> `libomptarget.nvptx.so` files on a system, including in system directories >> and in directories you have on your LD_LIBRARY_PATH. >> However, we want a clang to pick up its own versions of those files. The >> former is linked into clang, the latter is dynamically loaded with dlopen. >> That is, IIRC, roughly our use case. >> >>> I'd argue that such systems should specify -Wl,-rpath explicitly or in a >>> Clang configuration file. >> >> Could you work me through this, please. We can't install a config file in a >> user or system directory. So all we have is the clang install directory. >> Should we not set this flag but then install a file (by default) that says >> `-Wl,-rpath=...`. Is that what you mean? If so, what's the difference for >> the user? >> Or would we add `--offload-add-rpath` to the clang build if OpenMP offload >> is enabled? > > This part of https://clang.llvm.org/docs/UsersManual.html#configuration-files > is relevant "... is searched for sequentially in the directories". > > Say my `clang` executable is at `/tmp/opt/Rel/bin/clang`. I can just create > `/tmp/opt/Rel/bin/clang.cfg` with one line `-Wl,-rpath=/tmp/opt/Rel/lib` > (there is no magic expansion as in a shell). > Invoking `/tmp/opt/Rel/bin/clang` will get this default option (without an > unused command line option warning) unless `--no-default-config` is specified. > The difference is that the rpath is now the default, instead of only when > `-fopenmp=libomp` is specified. But such HPC users don't appear to be averse > to rpath as much as we do. > > It should be fairly trivial to adjust one's llvm-project build/install script > to create such a `clang.cfg` file. @jhuber6 Can you look into the last part, creating such a clang.cfg as part of the build/install process? The fact that rpath is always set is a difference but I doubt it's that bad. We effectively point only to the llvm runtimes, which should be what users want anyway. If this is really a problem, maybe we can/should separate the OpenMP runtimes into a subfolder and rpath (-L) that one. Users get by default the OpenMP runtimes associated with the clang, but we would not pollute anything else. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D143306/new/ https://reviews.llvm.org/D143306 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
