Thanks for your response Shoaib. I've got it building now. It required modifying the LLVM cmake scripts to include the libraries. 3.7 is a hard requirement. Cache file, great. Thanks!
On Thu, Apr 11, 2019 at 2:09 PM Shoaib Meenai <smee...@fb.com> wrote: > llvm-...@lists.llvm.org would also be a good place to ask questions about > the LLVM build system :) > > > > 1. I believe it’s just called the configure phase. (There’s also the > generation phase, where CMake actually generates the build system.) > 2. How have you set up your cross-compilation? LLVM’s build system has > logic to link pthread if needed, so I’m wondering why that’s failing. > 3. LLVM’s cross-compilation runs a sub-configure for some native build > components (e.g. TableGen) – perhaps one of those sub-configures is > succeeding but the main configure is failing? I’ve never seen the “Build > files have been written to” and “Configuring incomplete, errors occurred” > messages from the same configure. > 4. You can use a CMake cache file – see “-C <initial-cache>” in > https://cmake.org/cmake/help/latest/manual/cmake.1.html#options > > > > How come you’re working with LLVM 3.7, btw? That’s pretty old at this > point, and newer versions will have improved the build system (and it’s > also a lot easier to provide assistance for them). > > > > *From: *CMake <cmake-boun...@cmake.org> on behalf of SC Warrior < > bhh...@gmail.com> > *Date: *Wednesday, April 10, 2019 at 5:09 PM > *To: *"cmake@cmake.org" <cmake@cmake.org> > *Subject: *[CMake] cmake build of LLVM: HAVE_CXX_ATOMICS_WITHOUT_LIB test > failure > > > > I watched Chris Bieneman's talk > <https://www.youtube.com/watch?v=StF77Cx7pz8> about the transition of > LLVM from autoconf to cmake and he raved about how friendly / vibrant the > cmake community is so I thought I'd ask this here. I posted it to stack > overflow but it's fairly involved so I hope it's cool that I post (my > first) in this forum. > > > > I'm getting this failure trying to cross compile LLVM v3.7 (linux x64 -> > Aarch64) w/ cmake: > > <path to clang>/clang++ -DHAVE_CXX_ATOMICS_WITHOUT_LIB -std=c++11 -rdynamic > CMakeFiles/cmTC_82a21.dir/src.cxx.o -o cmTC_82a21 -lm -ldl && : > > ld.lld: error: undefined symbol: pthread_once > > referenced by cxa_exception_storage.cpp > > this is then followed by numerous other "undefined symbol: pthread_blah" > errors in the CMakeError.log file. > > I have four questions: > > (1) What is this phase of operation that cmake is performing to determine > the capabilities of the build environment / platform called ? (i.e. the > configure-like phase that performs numerous small compilation tests to see > if they succeed, looks to see if it can find header files in expected > paths, etc). > > (2) It looks to me that including -lpthread as part of the test > compilation line would fix this problem. (a) Is there a way to tell cmake > to do that and (b) is that a smart approach to solving this problem ? Seems > like if I could tell cmake to do this it would pass these tests. > > (3) The cmake command *seems* to succeed as it finishes with "Build files > have been written to ...". What should I make of that when one of these > pre-tests has a failure condition as cited above and reports "Configuring > incomplete, errors occurred!". > > (4) I'm trying to get this cmake cross compile build to work with the > stock LLVM v3.7 cmake files so I'm trying to control cmake using command > line options only. This gets a little ugly and I'm wondering if there's a > simple way to put all of these settings in a cmake file instead. One > problem with that approach is that I'm not familiar with all of the targets > in LLVM so if I were, to say, attempt to add libraries to targets to fix a > linking problem, I wouldn't know offhand what targets to add them to. I'm > hoping that in this case I can hit it with a bigger hammer and have them > added everywhere with hopes of them being ignored if not used. > > I gratefully thank you for your patience and time reading all of that ^^^. >
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