This is in preparation for the LLVM 4 upgrade (which gets more strict
about e.g., return false in xcbuild itself) and also for using xcbuild
more extensively in the Darwin stdenv bootstrap process, which is why I
killed the unnecessary gcc dependency in the toolchain. llvm-cov pretends
to be gcov anyway, so we're fine.
Splits outputs in clang like we do in 3.8 and 4.0 to avoid runtime
dependency on Python in the main derivation.
I also disable TSAN on Darwin to maintain consistency with 4.0, which
disables it because it forces an unfree dependency in the stdenv.
* All projects are available under NCSA license,
other than dragonegg.
* "Runtime" projects are dual-licensed under
both NCSA and MIT:
libc++, libc++abi, compiler-rt
* I don't mention MIT for compiler-rt as
we only build it as part of LLVM.
Fixes#18840: too large closure of mesa_drivers.
Tested atop 16.09:
- clang compiles a hello-world app;
- mesa seems to link OK;
- ispc builds.
Size comparison:
- 80 MB of full llvm-3.7 on 16.03;
- 200 MB of full llvm-3.9 on 16.09 before this patch;
- 50 MB of libLLVM after this commit.
