Building clang in buildworld as part of the bootstrap process -- is it really necessary?

[David Chisnall]

On 6 Sep 2014, at 06:47, Garrett Cooper <yaneurabeya at gmail.com> wrote:

> Makes sense. I'll do some poking around and see if things could potentially be optimized with the clang build. On beefy machines it's not a big deal, but as we know on machines without a ton of memory or SSDs, it can become painful, as expected.

The build system for clang-in-base has improved a bit so, as you say, it is now reasonably fast on beefy machines (release clang build with the upstream build system takes 2-3 minutes on a fast machine, about 10 on my laptop, the one in buildworld isn't quite as good at extracting parallelism).  On slow machines, it can be quite painful.

The correct solution to this problem is likely to be to start creating bootstrap-toolchain packages.  This is also likely to be necessary for architectures like MIPS and PowerPC before 11 anyway, because the host compiler doesn't have the C++11 support required for bootstrapping a newer LLVM and clang.  We can work around that quite easily if we have package for the bootstrap toolchain (possibly cross-compiled from an x86 machine).

David