Enable in-tree builds of parallel-libs.

[jlebar]

Summary

parallel-libs needs its own changes to make this work; these are just
the LLVM changes.

[beanz]

If you want to support parallel-libs building with just-built toolchains you may also want to ensure that it is compatible with the LLVM runtimes subdirectory.

If the intention is that it should not be built with just-built toolchains, you probably should add this under tools rather than projects.

[jlebar]

you may also want to ensure that it is compatible with the LLVM runtimes subdirectory.

Sorry, outside my depth: What do you mean?

[beanz]

The LLVM runtimes directory is a new mechanism in the CMake build system for building runtime libraries. It gives in-tree workflows while using just-built toolchains.

The last update on the effort is here:
http://lists.llvm.org/pipermail/llvm-dev/2016-August/104174.html

That also contains links back to the earlier discussions.

[jlebar]

All right, thanks.

We'll take a look at this, but it's a lot easier to collaborate if this is checked in, so I'm going to push it first, hope that's OK.

llvm/projects/CMakeLists.txt

 # Discover the projects that use CMake in the subdirectories.
 # Note that explicit cmake invocation is required every time a new project is
 # added or removed.
 file(GLOB entries *)
 foreach(entry ${entries})
   if(IS_DIRECTORY ${entry} AND EXISTS ${entry}/CMakeLists.txt)
     if((NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/compiler-rt) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/dragonegg) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libcxx) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libcxxabi) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libunwind) AND
-       (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/test-suite))
+       (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/test-suite) AND
+       (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/parallel-libs))
       add_subdirectory(${entry})
     endif()
   endif()
 endforeach(entry)
 
 # Also add in libc++ and compiler-rt trees if present (and we have
 # a sufficiently recent version of CMake where required).
 if(${LLVM_BUILD_RUNTIME})
   # MSVC isn't quite working with libc++ yet, disable it until issues are
   # fixed.
   if(NOT MSVC)
     # libc++ uses the libc++abi target names so libc++abi should be added
     # first.
     add_llvm_external_project(libcxxabi)
     add_llvm_external_project(libcxx)
     add_llvm_external_project(libunwind)
   endif()
   if(NOT LLVM_BUILD_EXTERNAL_COMPILER_RT)
     add_llvm_external_project(compiler-rt)
   endif()
 endif()
 
 add_llvm_external_project(dragonegg)
+add_llvm_external_project(parallel-libs)