I've used rr very sucessfully for reverse engineering a large code base using a break on variable change combined with reverse-continue. Took the time to extract critical logic way down.
rr – record and replay debugger for C/C++
41–50 of 134 posts
Re: rr – record and replay debugger for C/C++
#42Earlier quoted context omitted.
I don't understand the "rewrite X/Y/Z in Rust" trend that has been going for a few years. I'm not familiar with Rust, but I'm almost sure it has a good C interoperability. If a certain piece of software is working well, what is the benefit of rewriting it in Rust?
> If a certain piece of software is working well, what is the benefit of rewriting it in Rust? Presumablly the idea here is to support Rust replay debugging, not just rewrite a C/C++ targetting replay debugger in Rust
It works with pretty much any compiled language.
Re: rr – record and replay debugger for C/C++
#43Earlier quoted context omitted.
I don't understand the "rewrite X/Y/Z in Rust" trend that has been going for a few years. I'm not familiar with Rust, but I'm almost sure it has a good C interoperability. If a certain piece of software is working well, what is the benefit of rewriting it in Rust?
> If a certain piece of software is working well, what is the benefit of rewriting it in Rust? Presumablly the idea here is to support Rust replay debugging, not just rewrite a C/C++ targetting replay debugger in Rust
I'm not so sure of this. Most code in a debugger doesn't have much to do with the source language. Line mapping and figuring out values for variables happens via symbol information, eg. DWARF, and compilers for multiple languages can produce that in the same format.
Re: rr – record and replay debugger for C/C++
#44Has anyone gotten rr to work with opengl or vulkan? It seems to always crash for me after making an opengl call.
Re: rr – record and replay debugger for C/C++
#45Earlier quoted context omitted.
There's a bit of a higher abstraction ceiling in Rust so in theory if you are successful rewriting a thing in Rust then you now have a codebase that's easier to change confidently. This sort of property is nice to have in huge codebases where you really start losing confidence in shipping changes that don't subtly break things. But of course a huge codebase is hard to rewrite in general...
Sounds like a perfect situation for a strangler pattern? Wrap or transpile the original code into a language with stronger refactoring support and the rest should become incrementally easier.
The advantages of rust only come when you actually use the rust-provides abstraction, especially those around allocation and concurrency.
Even if transpiling is possible, the code would still not be structured I the rust way, and you wouldn't have any of the benefits. Same goes for wrapping.
Re: rr – record and replay debugger for C/C++
#46Earlier quoted context omitted.
I don't understand the "rewrite X/Y/Z in Rust" trend that has been going for a few years. I'm not familiar with Rust, but I'm almost sure it has a good C interoperability. If a certain piece of software is working well, what is the benefit of rewriting it in Rust?
There's a bit of a higher abstraction ceiling in Rust so in theory if you are successful rewriting a thing in Rust then you now have a codebase that's easier to change confidently. This sort of property is nice to have in huge codebases where you really start losing confidence in shipping changes that don't subtly break things. But of course a huge codebase is hard to rewrite in general...
> There's a bit of a higher abstraction ceiling in Rust
Compared to C, yes, but not compared to C++.
Re: rr – record and replay debugger for C/C++
#47Earlier quoted context omitted.
My previous job was in compiler engineering and I worked on upstream LLVM for a little while. rr was indispensable for me — not just for debugging, but as a tool for understanding how the compiler works in general. For example: you can set a watchpoint on an object in memory, and reverse-execute to the point where it was instantiated. This allowed you to answer questions such as ‘which optimisation pass was responsib…
I believe rr should support other languages exactly as well as gdb does; I've looked at some Rust in it once or twice at least, and IIRC even some Go; though I'm happy enough with doing assembly-level breakpoints/whatnot so I can't comment on more fancy things. Even some OpenJDK JIT! (though there of course source-mapping/stacktraces are non-existent, never mind reading variables, but even then I managed to hack toge…
I do know that RR works for Julia. Not sure why it wouldn't work for Go.
Re: rr – record and replay debugger for C/C++
#48Earlier quoted context omitted.
I don't understand the "rewrite X/Y/Z in Rust" trend that has been going for a few years. I'm not familiar with Rust, but I'm almost sure it has a good C interoperability. If a certain piece of software is working well, what is the benefit of rewriting it in Rust?
Recently the federal government issued a security advisory encouraging all new development to be done in Rust. I'm not sure the extent of which agencies this was meant to cover but it struck me as very unrealistic having just done years of java development for a state agency. https://www.nextgov.com/cybersecurity/2024/02/white-house-ur...
> the federal government issued a security advisory
Well, I guess that's it...
Maybe rust will take the same path as Ada.
Re: rr – record and replay debugger for C/C++
#49Earlier quoted context omitted.
There's a bit of a higher abstraction ceiling in Rust so in theory if you are successful rewriting a thing in Rust then you now have a codebase that's easier to change confidently. This sort of property is nice to have in huge codebases where you really start losing confidence in shipping changes that don't subtly break things. But of course a huge codebase is hard to rewrite in general...
> There's a bit of a higher abstraction ceiling in Rust Compared to C, yes, but not compared to C++.
This isn't really true. Rust has a much better type system. When writing generic code the impact is enormous.
C++ doesn't have a real Empty Type, and it thinks Units have non-zero size. In practical terms this makes it incredibly wasteful and in terms of a clear abstraction it encourages you to come up with a hack that's unclear but efficient.
Re: rr – record and replay debugger for C/C++
#50Earlier quoted context omitted.
I don't understand the "rewrite X/Y/Z in Rust" trend that has been going for a few years. I'm not familiar with Rust, but I'm almost sure it has a good C interoperability. If a certain piece of software is working well, what is the benefit of rewriting it in Rust?
There's a bit of a higher abstraction ceiling in Rust so in theory if you are successful rewriting a thing in Rust then you now have a codebase that's easier to change confidently. This sort of property is nice to have in huge codebases where you really start losing confidence in shipping changes that don't subtly break things. But of course a huge codebase is hard to rewrite in general...
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