[LLVMdev] How to bootstrap a bitcode file?

[Joachim Durchholz]

Hi all,

The question is:
Given a barebones nonroot shell account with no compiler and linker, 
what would be needed to execute a given bitcode file?

I several possibilities here.

On one end, the distributor simply compiles the bitcode to any platform 
supported and provides the binaries.
That means a 150% reliable cross-compiler setup for LLVM. Is that a 
realistic option?

On the other end, the distributor offers, for each platform supported, a 
simple LLVM backend in binary format, then use that to bootstrap a full 
optimizing LLVM backend for the current platform, finally compile the 
bitcode file to binary. (Keep the LLVM backend around so it can be 
reused for the next bitcode file.)
The snag here might be LLVM's dependency on the platform linker; since 
there is no root access, this requires supplying a locally-installable 
version of the linker infrastructure for the platform.

I also hear there's a bitcode interpreter around, which would be yet 
another option. Could either interpret the final bitcode file directly, 
or be used as the first stage of the bootstrap process.

Recommendations which path would be the most robust against breakage as 
platforms evolve?

Regards,
Jo