In my last post I've described how to use Z3 to find simple local peephole optimization patterns for the integer operations in PyPy's JIT. An example is int_and(x, 0) -> 0. In this post I want to scale up the problem of identifying possible optimizations to much bigger instruction sequences, also using Z3. For that, I am starting with the JIT traces of real benchmarks, after they have been optimized by the optimizer of PyPy's JIT. Then we can ask Z3 to find inefficient integer operations in thos...