I'm learning AArch64 assembly in the process of writing a code generator for it. godbolt.org is a great resource for "how do I do this?" Write a short function, run it through godbolt.org, see the instructions generated, lookup the instructions in the spec:

https://www.scs.stanford.edu/~zyedidia/arm64/encodingindex.h...

It'll be my keynote presentation at the D conference next month.