A parallelizing or vectorizing compiler for a sequential programming language must rearrange the execution order of program statements while still preserving the meaning of a computation. The goal of a compiler dependence analysis is to produce a dependence graph that captures which constraints on execution order are critical, so that the rest of them can be loosened. This dependence information can then be used to direct the generation of vectorized code in a semantics-preserving way. In this short talk, I’ll introduce a few basic notions of the theory of data dependence, drawn mostly from the first two chapters of “Optimizing compilers for modern machinery: a dependence-based approach” by Allen & Kennedy (http://dl.acm.org/citation.cfm?id=502981). To make the ideas concrete, JP Verkamp and I have been implementing a data dependence analysis for a tiny toy language, which I’ve dubbed “Loopy”. We’ll do a quick demo of our dependence analysis, which was implemented using syntax-rules, and if time permits (read: if I get it working in time!), I’ll show a second implementation done using the PLT Redex semantics engineering tools. Our work in progress is available at https://github.iu.edu/lkuper/find-deps.