Build cling with system provided llvm and clang


in my system I have installed both llvm and clang as standalone applications. I was wondering whether it is possible to build cling using them, without downloading whole llvm and clang repositories, like shown on this page:

Currently both llvm and clang are in 3.7.0 version.



It’s not. We have patches that transform llvm + clang into something that works for an interpreter. We are still planning to back-feed these patches, but for now you’ll have to use our branches.

Cheers, Axel.

Is there any update of back-feed process? Compile with whole LLVM is really a big problem for PC.

How is it a “big problem”? Do you mean it takes a lot of time? Is using ROOT binaries a reasonable work-around?

“big problem” is likely not the best wording, but having experienced it myself, I would say that it is a fairly “heavy task”. Also the whole llvm+clang+cling compiled package (including headers and dev tools) is around 1 GB for me. How much slimmer would a cling install relying on the system llvm be, maybe 10-to-100 times?

Cling is so much more than “the ROOT engine”. Many people outside HEP have little-to-no interest in ROOT, yet they make great uses of cling (and of the www :wink:).
I have this dream of having cling under the llvm umbrella, with integrated development cycles, shipping on the side of clang with the same feature support :upside_down_face:

Hi Dario,

Having cling part of the llvm tools universe would be great. I doubt it will happen anytime soon as we - sadly - don’t have the resources for it: in the fight sustainability versus acute problems, sustainability always comes in second.

As I said, installing ROOT can be seen as a workaround.

Cheers, Axel