libiomp 20150401

[tschoonj]

version bump
header installation path changed to prefix/include

see also discussion in #38707

[xu-cheng]

I think you need to update the test case in clang-omp as well. Also, from the backward compatibility aspect, maybe create a symlink to the original place? Will let the other maintainers decide it.

[tschoonj]

Ok, done. Will create a pull-request for clang-omp as soon as this is accepted

[tschoonj]

@xu-cheng ...and the test failed because the clang-omp test doesn't work anymore.

Any suggestions? the pull request for clang-omp will also fail because it will still use the old libiomp...

[xu-cheng]

Ok, done. Will create a pull-request for clang-omp as soon as this is accepted

You can update clang-omp in this PR.

[tschoonj]

Nice, it worked!

[tdsmith]

If I want to build something against OpenMPI with gcc while I have clang-omp installed, does having this header directly in HOMEBREW_PREFIX/include cause trouble for my gcc build? Ping @metacollin.

[ianml]

@tdsmith I haven't tested it out yet but it looks like only bin is linked, the headers are in libexec. e: Whoops, wrong formula. In this case omp.h is in the libiomp subdirectory.

[tschoonj]

@xu-cheng How about pulling this one in? Thanks!

[xu-cheng]

@tschoonj

• I would like to create symlink in old directory to keep backward compatibility.
• I'm not quite familiar to OpenMP and its relationship with different compilers. So will let @tdsmith decide whether we should merge this.

[tdsmith]

Oh, I see! This looks okay; I didn't notice the -I#{include} in the test. (Sorry, I've been afk for the last week.)

Ed: No, I was confused. I'll see what the bottle looks like when it's rebuilt.

[tdsmith]

@BrewTestBot test this please

[xu-cheng]

Ping @tdsmith

[tdsmith]

Oh, I let the damn build expire again, shame on me.

@BrewTestBot test this please

[xu-cheng]

@BrewTestBot test this please

[xu-cheng]

Ping @tdsmith in case you forget again. 😃

[tdsmith]

Thanks 😅

This does install a HOMEBREW_PREFIX/include/omp.h. It does not cause problems with gcc's omp implementation in the default prefix, because:

#include <...> search starts here:
 /usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.0.0/4.9.2/include <-- omp.h is here
 /usr/local/include
 ...

and -I/usr/local/include is always ignored. But if I add e.g. -I/Users/tim/.brew/include, it will not be ignored, and the libiomp omp.h will be found by gcc instead of gcc's omp.h.

I would like to not put this omp.h in the default search path. Can we teach clang-omp an additional default header search path?

[xu-cheng]

I think there is a talking that we should vendor libiomp inside clang-omp and boneyard this formula. It seems libiomp is only used by clang-omp. See #38707.

[xu-cheng]

Also FWIW, I would like to have clang-omp supported in homebrew compiler list. So if a formulaneed :openmp, we will choose clang-omp instead of gcc to avoid libc++ and libstdc++ incompatible problem.

[metacollin]

Sorry, been busy :(.

Custom include paths must be added by setting the precompiler define C_INCLUDE_DIRS to the paths. C_INCLUDE_DIRS is searched after the default search paths, so we can simply add whereever libiomp's include directory lives. One can find the actual #define near the top of llvm/tools/clang/include/clang/Config/config.h (It's the second or third define I believe).

Also, according to http://clang.llvm.org/get_started.html , cmake is the standard and preferred build system (I am not sure if this changed recently or its said that for a while and I never noticed heh). The cmakelists for clang will safely insert whatever we want into the config.h file, we simply pass -DC_INCLUDE_DIRS="#{homebrew_path_to_extra_include_dirs}" when calling cmake, and we're good to go. I've tested this and it works correctly. I am actually not too familiar with autotools, so if anyone knows a safe way to set that define without switching to cmake, the define we want is C_INCLUDE_DIRS.

Otherwise, we might consider switching the build system to cmake, which shouldn't be that big a problem.

Also, my personal opinion is that libiomp should remain a separate formula. It's a runtime library, one does not actually need it to build clang-omp, or even compile OpenMP aware programs, it is only needed to execute them. Intel releases new versions of the runtime fairly often, often with bug fixes and performance improvements, and it's an open OpenMP API runtime project, and can be used by any compiler, and should be a separate formula if only to make it available to developers using homebrew that are interested in adding OpenMP support to a compiler. And there is potential for other things to use the runtime, even if the only forumla currently using it is clang-omp.

But that's just my opinion, either way it's not going to be terrible if its separate, or terrible if its rolled in as a resource block in the clang-omp formula either. Just my two satoshis on the subject.

[metacollin]

D'oh, its done with --with-c-include-dirs=. 😐 🌴 (face palm).

Forget about the cmake stuff heh. For being so easy, it sure isn't documented anywhere in the clang online docs. I discovered it looking through the configure script.

I am going to do a pull request momentarily, I'm waiting for clang to rebuild to double check that this actually does what it's supposed to. I'm on a 2008 Mac Pro, so clang takes a while to build =/.

[tdsmith]

Neat; Formula["libiomp"].opt_include/"libiomp" is probably the path we want to add.

Is there a corresponding option for linking libiomp5.dylib?

[metacollin]

tdsmith, yep, that's what I am testing as we speak!

As for linking libiomp5, the name is unique, nothing will link to it unless it means to. If it were called libomp, it might be a problem, but there is one and only one library with the 'i' in front of the omp, and that's intel's runtime, with i signifying intel. Regardless, I am looking for info on how to add a custom lib search path to clang, but haven't found anything yet.

[tdsmith]

That makes sense; let's not worry about hiding the library. I think it could be helpful if Homebrew is installed to a prefix other than /usr/local but people who do that should know how to use LDFLAGS.

[xu-cheng]

clang-omp has been updated. @tschoonj Please update this accordingly. Thanks.

[tschoonj]

Nothing needs an update I think. I just tested it on my machine with the new clang-omp. Perhaps trigger a rebuild and see what happens?

[xu-cheng]

You need to rebase and remove the head file installation location change

[tschoonj]

this ok?

[xu-cheng]

Don't change this. It should be installed in include/libiomp now.

[tschoonj]

Ok, done

[metacollin]

Uh, please ignore my deleted posts. I completely misunderstood what was going on. Excited for this update :D Thanks tschoonj.

[xu-cheng]

Thanks for the pull request! 🎉 Homebrew depends on contributions from community members like you and we're grateful for your support.