LLVM Version / Alchemy Source Code

Question

Hi,
I wanted to get a better understanding of flash and decided to learn how the avm2 and alchemy works.  I would like to do some fun stuff with LLVM, including generating .swfs from other languages than c/c++. By trying so I noticed that Alchemy is based on LLVM 2.1 which is kinda old (released Sep 2007). Is there a way to use or port it to a newer LLVM version? It would make my experiment a lot easier and taking advantage of over three years development on LLVM would be great .
As far as I understand alchemy adds a new backend to LLVM arch=avm2 to generate avm actionscript code from LLVM IL code. Am I correct that this addition is not open source? Would be too bad, as I hoped to get an better understanding of the avm2 by looking into it. Also that would make it possible for us users of alchemy to port it ourself.
Thank you for any hints,
Florian

Answer 1

I think it's possible and I've been trying to do that for the last couple of days. I believe I've found out how the process works for compiling to iphone, using something similar to the alchemy toolchain. What I'd like to do is create an actioncript compiler with alchemy, so it basically is flash - flash, but taking advantage of all the optimizations that LLVM makes on bytecode, once you can understand it. I believe that adobe uses the following process:
compile .as to ABC.
Pass ABC into the GlobalOptimizer that exists inside the actionscript compiler (ASC.jar).
It appears that GlobalOptimizer produces SSA IR code. I believe adobe slightly modifies this to be LLVM IR, and then they can just run llvm-as on the generated LLVM IR code.
I'm working on getting this functioning right now, because if I can get these stages done, then the existing alchemy toolchain should do the rest of the job (that is, taking that llvm bytecode and outputting actionscript bytecode using the existing back end). This would also explain why Adobe hasn't updated alchemy to work with a new version of LLVM, because the LLVM IR spec changes from release to release, so they'd have to keep changing the process of formatting their GlobalOptimizer output to be LLVM IR, which is probably more work than they want to invest right now.
In this list of processes, I'm on the last one. I'm currently figuring out how to convert the output from GlobalOptimizer to be valid LLVM IR but honestly, this is ALL new territory for me I need to find the specs on these things and do some reading. I had to customize the source code of the actionscript compiler to get this to work at all this far. The very fact that I had to do this also points to the fact that I'm on the right track, since posts I've seen from Adobe employees + documentation state that the actionscript compiler included in the alchemy toolkit is custom. Plus, this paper confirms many of these conclusions:
http://llvm.org/devmtg/2009-10/Petersen_OptimizingActionScriptBytecode.pdf
I think you might be the only person interested in this stuff so for the sake of not clogging up the forums with our discussions feel free to contact me directly if you'd like more info.