[PATCH] D57128: Add --unwindlib=[libgcc|compiler-rt] to parallel --rtlib=

[Petr Hosek via Phabricator via llvm-commits]

phosek added a comment.

This has broken all our toolchain builders (https://luci-milo.appspot.com/p/fuchsia/g/clang/console). These are using the runtimes build https://github.com/llvm/llvm-project/blob/master/llvm/runtimes/CMakeLists.txt which can be used to build compiler runtimes using the just-built Clang. The way that works is runtimes build first builds builtins for all specified targets (by invoking builtins build directly in https://github.com/llvm/llvm-project/blob/master/compiler-rt/lib/builtins/CMakeLists.txt), and then as second step builds remaining runtimes (libunwind, libc++abi, libc++, and the rest of compiler-rt). Now, with this change this breaks the second phase because where before Clang has been only looking for compiler-rt builtins (which have been built in the first phase) now Clang is also looking for `-luwind` which hasn't been built yet. There's actually a cycle because CMake checks ran by libunwind build are looking for libunwind (I see a lot of `ld.lld: error: unable to find library -lunwind` errors in the CMake log).

I think we'll probably need to update the CMake build to pass `-nostdlib` when running the checks in llvm/cmake/modules/HandleLLVMOptions.cmake (that's invoked from https://github.com/llvm/llvm-project/blob/master/llvm/runtimes/CMakeLists.txt#L117). However, it'll take a me while to prepare that change and test it, is there any chance we could revert this in the meantime?


Repository:
  rL LLVM

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  https://reviews.llvm.org/D57128/new/

https://reviews.llvm.org/D57128