Evaluate support of optimised IR translation

Current use case of translator assumes that non-optimised IR is given.

A number of questions that were asked recently are as follows:
- Do we have any idea what issues do we have with optimised IR? Would it be worth running a some tests and collect the issues we find?
- Is this a valuable use case?
- Would support for this be easier to implement in a LLVM backend rather then translation format?

Start with the questions in issue #203 and investigate how the translator currently assumes non-optimised IR. Compare the potential LLVM backend and translation-format approaches, and evaluate whether tests should be run against optimised IR. Done means recording the compatibility issues, value of the use case, and a decided implementation direction.

Written by the indexing model from the issue text.