Compilation for Explicitly Managed Memory Hierarchies

Authors: Timothy J. Knight, Ji Young Park, Manman Ren, Mike Houston, Mattan Erez, Kayvon Fatahalian, Alex Aiken, William J. Dally, Pat Hanrahan

Paper: http://graphics.stanford.edu/papers/sequoia-compiler/sequoia_ppopp07.pdf

Cool little paper on optimizing IL code for parallel processors (ostensibly Cell). (As I read it, it became obvious I should have read the Sequoia paper first, but whatever). The interesting piece was the explicit modeling of memory as a tree. Consider, for instance, several processors each with their own local memory and then, say, a single shared main memory. The IL models operations based on this memory hierarchy, for example copying between memory layers, performing computation on a given layer, etc. It's not clear to me whether this does, in fact, model anything other than Cell (processor), but it's kind of a cool idea nonetheless.

I was less interested in the actual optimizations they did, which seem to give benefit to Sequoia programs, than I was in how they model their system (because I'm thinking about programming models for heterogeneous processing environments at the moment). They seem to do some fairly straightforward things like introducing dependencies to ensure orderings where needed, loop hoisting, copy elimination, etc.