Blogs

My eldest son likes collecting things. Of course all children seem to like picking up random objects and hoarding them forever, and we’ve had our fair share of leaves, stones, food wrappers and other assorted paraphernalia floating around the house until we can divert attention elsewhere and get rid of them. But my son also really likes collecting sets of toys, books and, currently, stickers.

He first got into this during the World Cup in 2014 when I thought he was old enough to really enjoy collecting the stickers of all the players and teams that you find in the famous Panini sticker album that’s published before each competition. I remember collecting these when I was growing up; the excitement at opening each pack...

One of the most important parts of our HELIX compiler is the data dependence analysis we run on the compiler’s IR to determine which instructions are independent of each other. You can read more about HELIX in general in our original CGO 2012 paper (click through my publications page to get free access to the ACM version).

HELIX’s initial data dependence pass is split into two phases, and it’s the memory alias analysis stage that is most interesting. This has the job of identifying the locations in memory that are read and written by each instruction so that we can respect all data dependences within the loops we parallelise. Since alias analysis is not precise, we need to...

It sounds a bit counter-intuitive, but boosting application performance by limiting the amount of vectorisation carried out is essentially what my postdoc, Vasileios Porpodas, and I have done in our latest paper on automatic vectorisation. We call it TSLP, or Throttled SLP, because it limits the amount of scalar code that the standard SLP algorithm converts into vectors.

The actual paper is available here . Vasileios presented it at PACT last week and will be at the LLVM Developers’ Meeting this week, so I thought it might be interesting to expand on one of the examples we give at the end, showing the source code and how it is actually vectorised with SLP and TSLP. The kernel is compute-rhs, which is a...

Today is the first day I’m officially employed as a University Lecturer , so it seems appropriate for my research blog to be born right now. It’s going to be a bit of an experiment (as you’d expect), but hopefully a place where I can describe the research my group is undertaking in more detail, in a different way to how it’s presented in our papers, and with interesting results that we don’t intend to publish in any conference or journal. My aim is to make the research more accessible and informal than our academic articles. Let’s see how I get on!

Cheers Tim