lldb-mi VS rr

When using a debugger such as gdb or lldb, typically you:

I'm on the record of loving the VSCode experience with Rust. And I do think that it's amazing that a "non-IDE" can feel so much like an IDE. However, I've recently pivoted off of that stance. I know it's still in EAP, but Rust Rover gives me all of the things that I get from VSCode plus an easier integration with LLDB.

Fortunately, we can use this same technique with our Node.js applications! This is possible through llnode: a LLDB plugin which enables us to inspect Node.js core dumps. With llnode, we can inspect objects in the memory and look at the complete backtrace of the program, including native (C++) frames and JavaScript frames. It can be used on a running Node.js application or through a core dump.

An alternative to gdb is lldb. But I like gdb.

The CMake-based, itk-wasm build system tooling enables the same C++ build system configuration and code to be reused when building a native system binary or a WebAssembly binary. As a result, native binary debugging tools, such as GDB, LLDB, or the Visual Studio debugger can be utilized.

The debugger component of the LLVM project. It’s what you’re typing into when you type po someExpression. https://lldb.llvm.org/ Web searches could help explain a lot of this for you 😊

If you really don't want to touch Visual Studio/MSVC then you can try to compile with clang and use lldb: https://lldb.llvm.org/

LLDB - https://lldb.llvm.org/ - Debugger from the LLVM project

Well, there's LLDB (https://lldb.llvm.org/) - I've heard it's got some nifty architectural features (e.g. having access to the Clang framework for handling C/C++ expressions).

I've done some minimal poking about in the code; I found its object-orientation a bit hard to grok (just for me personally) but it seemed to be quite uniformly applied so it might well be easier to work with.

The article does mention lldb as a future target.

https://learn.microsoft.com/en-us/windows-hardware/drivers/d...

Or on Linux use rr (https://rr-project.org/) or Undo (https://undo.io - disclaimer: I work on this).

These have the advantage that you only need to repro the bug once (just record it in a loop until the bug happens) then debug at your leisure. So even rare bugs are susceptible.

rr and Undo also both have modes for provoking concurrency bugs (Chaos Mode from rr - https://robert.ocallahan.org/2016/02/introducing-rr-chaos-mo..., Thread Fuzzing from Undo - https://undo.io/resources/thread-fuzzing-wild/)

> IntelliTrace is one that comes to mind - there’s nothing remotely close to it’s snapshot debugging that I’ve seen anywhere else, and I’ve really looked.

https://rr-project.org/

Hi, in case you're not already aware of the name clash, there's already a `rr` in the programming world. It's "record and replay": https://rr-project.org/.

Very different, but a very fine tool tool.

I don't know, however a key element is:

> Record/replay system is based on saving and replaying non-deterministic events

> The following non-deterministic data from peripheral devices is saved into the log: mouse and keyboard input, network packets, audio controller input, serial port input, and hardware clocks (they are non-deterministic too, because their values are taken from the host machine). Inputs from simulated hardware, memory of VM, software interrupts, and execution of instructions are not saved into the log, because they are deterministic and can be replayed by simulating the behavior of virtual machine starting from initial state.

So, it's probably not much, you can probably comfortably save minutes of qemu sessions.

Also note the existence of the rr debugger [1], which allows you to reverse debug applications with a ~10% performance hit while recording. To achieve this, it records results of syscalls (only). It will serialize thread events, so have the effect of running applications like on a single core CPU.

[1] https://rr-project.org/

rr.

rr rr rr rr.

rr!

When testing "algorithmic" modules like compilers, it's basically a productivity cheat code to run the tests under https://rr-project.org/. Doing so allows you to deterministically replay execution, seeking forwards and backwards in the timeline of your program's execution, and quickly locate what went wrong in any computation.

For example, if we have

    struct CircleDescription {

It says on https://rr-project.org/ that it supports Go programm, what's the status?

This was because no matter how hard I tried, I kept running into variables that I was watching that appeared to be the same reference, have different values (so I know I was referring to something wrong, but could not for the life of me figure it out, and though if I only had a way to step/trace and do this visually like an AST that highlights changed values and you could see back to its root where it's actually being modified visually)

I found out there's a thing called "deterministic debugging" (and the biggest known example afaict is rr: https://rr-project.org/

Apparently MS has a time-travel debugger... I pictured the AST being populated and repopulated via the steps, and the ability to diff changes over time.

Here's a wiki on various systems, though most of these seem to be typical text based "trace" options.

https://en.wikipedia.org/wiki/Time_travel_debugging