Author here. The generated LLVM IR at the bottom actually make uses of vector instructions, which will make LLVM generate SIMD instructions if supported by the CPU.

For instance, try entering just a long word as the regex, e.g. "helloworld":

  %state0.goto.1.0.cmp_mask = icmp eq <10 x i8> %state0.rhs, < i8 104, i8 101, i8 108, i8 108, i8 111, i8 119, i8 111, i8 114, i8 108, i8 100 > ; helloworld