[llvm-dev] [help] How to speed up compilation?

[Renato Golin via llvm-dev]

On 18 October 2016 at 17:56, Sunghyun Park <sunggg at umich.edu> wrote:
> Personally, it feels like compilation become much slower than previous
> versions after adopting 'cmake'.
> Is this natural when we adopt cmake or are there other big changes on build
> structure?

So, I decided not to respond to that specific part of your original
post because I don't have enough information on what you changed, but
we have deprecated autoconf for a while now, so everyone uses CMake.

If you're comparing LLVM a long time ago with autoconf versus LLVM
today with CMake, then the changes are most likely because LLVM has
grown a lot.

If you're building LLVM trunk today with autoconf, then it's possible
that you're missing a lot of source files from your build (and I'm
surprised it worked).

But overall, CMake should make absolutely no difference in building
speeds, since the number of compilation jobs should (hopefully) be the
same and in the same way. But I may be missing something... :)

cheers,
--renato