July 9, 2025 (1mo ago):

• rudy is Rust-specific debuginfo tooling. By default, cargo build invokes rustc with -g and outputs debug info with the binary. On MacOS and Linux, rustc emits DWARF debugging info.
• rudy consists of rudy-dwarf for directly interacting with DWARF info and rudy-db for a higher-level interface. Its two main goals are to improve Rust debugging with lldb via rudy-lldb and build foundational tooling.

Rudy LLDB:

• rudy-lldb is a small application using rudy-db to provide an extension for lldb. It works by adding the Python client to ~/.lldbinit, connecting to a locally-running server over TCP, and using rudy-db to query and forward information.
• It extends lldb with Rust-specific functionality, understands Rust types and their memory layouts, and differentiates between functions, methods, and trait implementations.

Rudy Dwarf:

• rudy-dwarf is a "medium-level" library for interacting with DWARF info, sitting above gimli. It provides indexes for fast lookups, parser combinators for extracting data, and a visitor trait.
• The parser is based on the Parser trait, which takes a salsa database and a Die (an opaque wrapper around an offset) and parses the DWARF info. Parser combinators like all are used to combine multiple parsers.
• For example, complex Rust types like enums can be parsed using reusable components, and parser combinators make it easy to build custom functionality.

Using Salsa:

• The project initially aimed to build a Rust-specific debugger but was split into rudy. salsa is used for incremental computation and caching in rudy-dwarf and rudy-db.
• On MacOS, rudy-db computes indexes quickly for small projects (20-30ms) and larger projects (1-2s). Individual operations are fast after indexing (around 1ms for small, 10ms for large).
• There are improvements to be made, especially on Linux where indexing the entire binary upfront is expensive. A follow-up post is planned to discuss the use of salsa in more detail.

Digression: Why do we need better debugging tooling for Rust?:

• The author has used Rust for over 10 years and only used interactive debuggers for stack overflows. Print debugging can be a trap, and it would be helpful to have an interactive debugger to query the system state.
• rudy aims to make lldb debugging a viable option and provide foundational tooling for the next generation of debug tooling.