Feature Request: support compilation from tarball [PoC, don't merge]

[smarr]

This is more of a feature request than a PR.

I'd like to be able to build Graal from a source tarball for the use in artifacts.
The attached patch introduces a stub for a VC in mx, that does achieve that.

However, it's not a general solution, because the suite structure is somewhat hard coded.

Nonetheless, it supports the following use case:

cd graal-jvmci-8
mx clean
mx build
export JAVA_HOME=`../mx/mx jdkhome`
cd ..

cd graal/compiler
export JVMCI_VERSION_CHECK=ignore
mx clean
mx build
mx makegraaljdk $OUT/graal-core

If this is something that would be generally useful, any idea how this could be realized less hacky?

Thanks!

[gilles-duboscq]

Something like that would be useful.
In principle mx should support the case where the vc and vc_dir fields of the Suite are None.
I'm not sure what's easier though: make an artificial VC or fix the code that accesses vc and vc_dir.

As you note in your commit, there needs to be some meta-data in the suite.py file to figure out at what depth the root of the "repo" is.