Here, I would disagree with you in part. There are more than two topics that are needed. First. Design your language if you are not going to use something that

Here, I would disagree with you in part. There are more than two topics that are needed. First. Design your language if you are not going to use something that already exists. So you need to understand grammars and the various pitfalls. There are quite a number of tutorials on this subject freely available around the web. Second. Understand what you want your language to actually mean, this is the subject of semantics. So if you are starting out, make a simple grammar and simple associated semantics. Again there is various material around the traps that you can avail yourself of. Third. Have a look at the various parser generators out there and what they expect in terms of your language. There are many and each has its pros and cons. Again, there are various tutorials about the subject. Fourth. If your language is relatively simple and has relatively simple semantics, see what is required for the generation of LLVM IR. If there is any complexity in the language and its semantics, LLVM IR may not necessarily be the way to go. So, back to the first and second points, keep your investigatory language simple in both its syntax (grammar) and its semantics. Fifth. Have fun. The entire subject can be a delight to learn, but some of the material out there is deadly boring and will quickly turn most people off the subject. But it is actually fun. Son enjoy the time you spend learning about the subject.