Fascinated by the JIT

by Miguel de Icaza

Some people think that I wrote the Mono JIT. I did not. Dietmar, Paolo, Zoltan and Martin are the people who have hacked on the JIT engine in Mono.

Recently, as a side project, I have been playing with the JIT a bit to improve some code generation here and there, and together with Ben we are learning how it works internally, it is fascinating to watch it in action.

We have been using a simple example: String.GetHashCode hoping to get things to the point where the JIT output matches GCC -O3. The code is slightly smaller than GCC, but it is wasting two registers, so in a tight loop it ends up placing a local variable on the stack which has a high impact on a tight loop.

Managed C++ and Mono

Someone on IRC pointed me a few days ago to Open64. A compiler suite that includes C, C++ and Fortrans that generate a new intermediate representation called `WHIRL'.

Some of the compiler front-ends are the GNU compiler front ends that have been re-targeted to generate WHIRL instead of RTL. This is fascinating because it means we can now seriously consider implementing the ECMA managed extensions to C++ (the job of moving to a non-RTL IR was done by SGI).

It also means that any compiler that is moved to generate WHIRL could run on any ECMA VM.

You can get the WHIRL IR documentation from here

CIL image manipulation

This topic keeps coming up: are there tools to manipulate CIL images (instrument code: pre- and post- processing, add classes, remove classes, trim methods, replace methods, append instructions) and sometime ago the fine folks at the University of Coimbra have implemented such a tool: Runtime Assembly Instrumentation Library

In Chicago

The other day Nat and I met David Vaskevitch, Microsoft's CTO. We went dancing.

Posted on 12 Apr 2004