Julia: llvm-3.9.0_threads.patch breaks the build on FreeBSD

[ararslan]

Our patched LLVM 3.7 built fine on FreeBSD, but it seems that LLVM 3.9 refuses to build on FreeBSD when llvm-3.9.0_threads.patch is applied. The following message is displayed, along with several other similar messages referencing other LLVM files:

CMake Error at cmake/modules/LLVMProcessSources.cmake:83 (message):
  Found unknown source file
  /usr/home/alex/repos/julia/deps/srccache/llvm-3.9.1/tools/lli/OrcLazyJIT.cpp


  Please update
  /usr/home/alex/repos/julia/deps/srccache/llvm-3.9.1/tools/lli/CMakeLists.txt

The build works fine if the application of this patch is commented out.

This is with CMake 3.7.1. I guess the patch was copied from Rust's fork of LLVM, so this issue may not be unique to Julia.

[tkelman]

try taking this section out of the patch https://github.com/JuliaLang/julia/blob/d7b6ac31025d8ca685ef9e725ea81981346bc50e/deps/patches/llvm-3.9.0_threads.patch#L331-L337 (then distcleaning llvm)

[ararslan]

For reference, the more complete log from building LLVM is here. I'll try your suggestion and see what happens. Thanks as always, Tony!

[ararslan]

Looks like your suggestion plus the removal of this section got it building. 🎉

[ararslan]

I'm getting a ton of messages that say that libjulia.so contains undefined references to LLVM things. For example, here are the first few such messages:

/usr/home/alex/repos/julia/usr/lib/libjulia.so: undefined reference to `llvm::object::object_category()'
/usr/home/alex/repos/julia/usr/lib/libjulia.so: undefined reference to `llvm::ConstantExpr::getCompare(unsigned short, llvm::Constant*, llvm::Constant*, bool)'
/usr/home/alex/repos/julia/usr/lib/libjulia.so: undefined reference to `llvm::InsertValueInst::init(llvm::Value*, llvm::Value*, llvm::ArrayRef<unsigned int>, llvm::Twine const&)'
/usr/home/alex/repos/julia/usr/lib/libjulia.so: undefined reference to `llvm::ConstantInt::getSigned(llvm::Type*, long)'

For the full section of the log, see here. Though I should note that these messages occur even when this patch is not applied at all, which may indicate that they aren't related to this particular issue. I can open a separate issue for that if that would be better.

[tkelman]

do the linker errors happen if you don't apply any of our patches to llvm at all?

[ararslan]

Actually yes, they do. I guess those errors probably has more to do with LLVM 3.9 on FreeBSD in general than with our patches.

Edit: LLVM 3.9 is available from FreeBSD's pkg and ports though, so it's not like it's not supported.

[tkelman]

It would be good to put together a Vagrantfile for the FreeBSD build at some point so it's easier to test against.

[tkelman]

Ooh, I think I know why this is FreeBSD-specific. Apparently when patch behaves in a way that strictly conforms to POSIX, it doesn't remove empty files by default. GNU patch, which I think Apple might also use (?), does. First, if a file exists at deps/srccache/llvm-3.9.1/tools/lli/OrcLazyJIT.cpp, how big is it? Try adding -E to the patch call here https://github.com/JuliaLang/julia/blob/c38a5a3044ffd62c585225a201422f95fd18f6dc/deps/llvm.mk#L432 and see if that fixes this issue.

[tkelman]

Scratch that, looks like busybox-based systems don't support patch -E so we shouldn't assume it's available. Try the commits I just added to #19810 (starting from distclean'ed llvm) which should hopefully make it unnecessary.

[ararslan]

Thanks, Tony!