What is New in Cross Compiling Haskell

July Edition

In July I’ve been playing around a bit more with -target . At this point I believe the best solution is to have a minimal ghc that doesn’t ship with any libraries; and all libraries are built on demand per target. We will likely want to pre-build and ship the Runtime System Library rts as we do not have a cabal package that would just build the rts . You’d have to specify the targets for which you want to build/include the rts . The drawback is that you’d need the (partial) target toolchain to build the rts for all the bundled rts s you want to ship.

On the other side you’d likely want to use iserv (e.g. the -fexternal-interpreter ), with which I’ve just recently run into some strange behaviour while compiling test-suites for packages, where the iserv process complains about code that is loaded multiple times. I’m currently exploring how we can get proper test-coverage for libraries, and maybe even ghc in a cross compiled setting.

A few bugs were fixed, the -staticlib argument now doesn’t fail if the object files in the archives it’s trying to concatenate are of odd-length; GHC doesn’t PANIC anymore when -jN , N>1 is used and it fails to find/load a library.

I’ve also updated the relevant llvmng code to work with ghc8.6. I’ve had to retract the performance improvement though; as it kept producing invalid binaries occasionally and I haven’t found the reason yet. As such I’m probably going to rent some compute time on AWS or similar service to build the cross compiler once the final 8.6.1 hits.