Sista VM Screencast

Hi all,

Recently I gave a demo at HPI on how I use the Cog VM simulator to step into machine code while simulating a Pharo image. Normally I like to do blog posts and I don’t like videos (videos take more time to do and I don’t like my French accent which makes them hard to follow), but it’s really difficult to explain what I am doing in this case without a video. Therefore I made a screencast where I show how I track down bugs in the Sista optimized code and how I debug them in the Cog VM simulator through machine code single stepping. If want to read a blog post on the VM simulator instead of a video you may want to look at one of my old blog posts here.

The video shows first how I build an image crashing at start-up on an optimized Sista method. Second, it shows how I simulate it with the VM simulator, including how I set different kinds of break point in machine code compilation and execution to track down where the problem comes from.

The image used for VM simulation can be built following those instructions.

I hope you will like the screen cast. Don’t hesitate to ask questions. Sorry for the French accent.