proguard VS proguard-core

https://github.com/Guardsquare/proguard (not the best but it does work)

Nice project! At Guardsquare, we have a similar project: https://github.com/Guardsquare/proguard-assembler

One of the things we use it for is testing: we can craft specific bytecode sequences that we want to test; for example, it's useful to test cases we've seen in the wild (e.g. obfuscated code) or to create a test that doesn't rely on a specific compiler/version.

An example of using the assembler from a ProGuard unit test https://github.com/Guardsquare/proguard/blob/master/base/src...

ProGuard is free and open-source; https://github.com/Guardsquare/proguard

With the upcoming release of AGP 7, ProGuard needs a new way of integrating into Android projects. Therefore, as part of the latest ProGuard 7.1 release, we developed a Gradle plugin for ProGuard. With this plugin ProGuard integrates into your existing gradle process, so that you can keep using ProGuard with AGP 7. You can find the plugin in the ProGuard GitHub repository.

Anyways, have you looked at Proguard core?

For generating Java bytecode/class files you could take a look at ProGuardCORE . It's a bytecode manipulation and analysis library that grew out of ProGuard.

The MethodBuilder "low-level" example looks like the ProGuardCORE API for building classes & code sequences, which can be written as:

Something else that could make your code generation for your JVM language easier: ProGuardCORE (https://github.com/Guardsquare/proguard-core). It can be used to read, generate and analyse Java bytecode.

Some examples for code generation: ProGuard where the project originated (https://github.com/Guardsquare/proguard), Brainf*ck compiler (https://github.com/mrjameshamilton/bf), Lox compiler (https://github.com/mrjameshamilton/klox)

Disclaimer: I work at Guardsquare on ProGuardCORE so may be biased ;)

I implemented Lox in Kotlin based on the book's Java interpreter then added a JVM backend using ProGuardCORE: https://github.com/mrjameshamilton/klox

You can find out more about ProGuardCORE on GitHub and the manual contains some further examples.

Not a book or guide but a useful library for working with/generating JVM class files is ProGuardCORE. It's the underlying library used by ProGuard and I also recently used it to add a JVM backend to my implementation of Lox from the Crafting Interpreters book.

After completing the first part of the book (using Kotlin instead of Java), I added a JVM backend using ProGuardCORE (https://github.com/Guardsquare/proguard-core).

The biggest difference is our initial goal of creating a tool for application developers rather than a security team. This means we aim to exclude information that the application developer definitely knows and doesn't want to see again, e.g. the list of permissions an application is requesting. Furthermore we try to focus on nice and intuitive UX that is familiar to this audience, enabling an application developer to be very efficient in reading & interpreting the results (e.g. easy comparison of two builds). Also note that this is built on the same core technology as ProGuard. This foundation of compiler components (e.g. our partial evaluator) and the knowledge and experience at Guardsquare that comes with it will unlock many more in-depth code checks.