[Mono-dev] Using libJIT in Mono Instead of LLVM

[Miguel de Icaza]

Hello,

> I have already sent two emails in this mailing list. Most likely their
> will be not accepted here. So I want to ask your opinion, about a
> possible cooperation of using libJIT as another engine for Mono
> instead of LLVM. 

You can post patches in this list, but for us to integrate the code into
Mono, you would have to sign a copyright assignment for the code to
allow Novell to relicense the code as we actively relicense Mono for
people that do not want to use the LGPL.

Just to set expectations right: currently we are not planning on
replacing Mono's code generation engine to LLVM or another JIT engine.
We are very happy with the balance that we have reached in terms of
startup performance and code generation quality as well as the wide
reach of platforms that Mono supports.

The work on the LLVM backend at this point is a research project from
Zoltan and is far from ready.   Adding a new backend to the list of
backends or interfaces to maintain is likely going to be a lot of work
at this point, and any cycles that we spend are going to go towards
integrating LLVM due to the other optimizations present on it.   Feel
free to plug your engine and post patches here for discussion as you
move along, or join us in the IRC channels.

The research into LLVM is mostly with an eye towards batch compilation,
where folks can afford slow compile times in exchange for more
optimizations being applied to the code.   This is something that JIT
engines can not afford to do as they have to compile code quickly to
keep startup time to a minimum.

Miguel.