What formal representation is commonly used to describe compiler optimizations?

Question

I have devised a compiler optimization that works on any structured language that has arrays assignments array[index] = value and counted loops (for i = n; i < N; i++) {doTHIS} (*).

Now I want to represent this optimization using some formal semantics. Since I want to publish my results in a Programming Languages venue, I would like to know:

What formal(s) representation(s) is (are) most commonly used to describe compiler optimizations?

I have already described my optimization using operational semantics, but I'm currently reviewing this choice. Hence, I came to the community for advice.

(*) Please forgive this C-like representation in a question asking for formal semantics.