pancake :radare2:<p>2025 and clang-format still can't enforce a space before function calls <a href="https://releases.llvm.org/20.1.0/tools/clang/docs/ClangFormatStyleOptions.html" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">releases.llvm.org/20.1.0/tools</span><span class="invisible">/clang/docs/ClangFormatStyleOptions.html</span></a> <a href="https://infosec.exchange/tags/llvm" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>llvm</span></a> <a href="https://infosec.exchange/tags/clang" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>clang</span></a> <a href="https://infosec.exchange/tags/format" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>format</span></a></p>
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*Very* damning indictment of #GitHubCopilot as a professional-grade #programming tool from a former core #FreeBSD team member and current #LLVM and #IoT developer.
https://infosec.exchange/@david_chisnall/113690087142854474
My favorite bit:
> “It’s great for boilerplate!” No. APIs that require every user to write the same code *are broken*. Fix them, don’t fill the world with more code using them that will need fixing when the APIs change.
Infosec ExchangeDavid Chisnall (*Now with 50% more sarcasm!*) (@david_chisnall@infosec.exchange)I finally turned off GitHub Copilot yesterday. I’ve been using it for about a year on the ‘free for open-source maintainers’ tier. I was skeptical but didn’t want to dismiss it without a fair trial.
It has cost me more time than it has saved. It lets me type faster, which has been useful when writing tests where I’m testing a variety of permutations of an API to check error handling for all of the conditions.
I can recall three places where it has introduced bugs that took me more time to to debug than the total time saving:
The first was something that initially impressed me. I pasted the prose description of how to communicate with an Ethernet MAC into a comment and then wrote some method prototypes. It autocompleted the bodies. All very plausible looking. Only it managed to flip a bit in the MDIO read and write register commands. MDIO is basically a multiplexing system. You have two device registers exposed, one sets the command (read or write a specific internal register) and the other is the value. It got the read and write the wrong way around, so when I thought I was writing a value, I was actually reading. When I thought I was reading, I was actually seeing the value in the last register I thought I had written. It took two of us over a day to debug this. The fix was simple, but the bug was in the middle of correct-looking code. If I’d manually transcribed the command from the data sheet, I would not have got this wrong because I’d have triple checked it.
Another case it had inverted the condition in an if statement inside an error-handling path. The error handling was a rare case and was asymmetric. Hitting the if case when you wanted the else case was okay but the converse was not. Lots of debugging. I learned from this to read the generated code more carefully, but that increased cognitive load and eliminated most of the benefit. Typing code is not the bottleneck and if I have to think about what I want and then read carefully to check it really is what I want, I am slower.
Most recently, I was writing a simple binary search and insertion-deletion operations for a sorted array. I assumed that this was something that had hundreds of examples in the training data and so would be fine. It had all sorts of corner-case bugs. I eventually gave up fixing them and rewrote the code from scratch.
Last week I did some work on a remote machine where I hadn’t set up Copilot and I felt much more productive. Autocomplete was either correct or not present, so I was spending more time thinking about what to write. I don’t entirely trust this kind of subjective judgement, but it was a data point. Around the same time I wrote some code without clangd set up and that *really* hurt. It turns out I really rely on AST-aware completion to explore APIs. I had to look up more things in the documentation. Copilot was never good for this because it would just bullshit APIs, so something showing up in autocomplete didn’t mean it was real. This would be improved by using a feedback system to require autocomplete outputs to type check, but then they would take much longer to create (probably at least a 10x increase in LLM compute time) and wouldn’t complete fragments, so I don’t see a good path to being able to do this without tight coupling to the LSP server and possibly not even then.
Yesterday I was writing bits of the CHERIoT Programmers’ Guide and it kept autocompleting text in a different writing style, some of which was obviously plagiarised (when I’m describing precisely how to implement a specific, and not very common, lock type with a futex and the autocomplete is a paragraph of text with a lot of detail, I’m confident you don’t have more than one or two examples of that in the training set). It was distracting and annoying. I wrote much faster after turning it off.
So, after giving it a fair try, I have concluded that it is both a net decrease in productivity and probably an increase in legal liability.
Discussions I am not interested in having:
- You are holding it wrong. Using Copilot with this magic config setting / prompt tweak makes it better. At its absolute best, it was a small productivity increase, if it needs more effort to use, that will be offset.
- This other LLM is *much* better. I don’t care. The costs of the bullshitting far outweighed the benefits when it worked, to be better it would have to *not bullshit*, and that’s not something LLMs can do.
- It’s great for boilerplate! No. APIs that require every user to write the same code *are broken*. Fix them, don’t fill the world with more code using them that will need fixing when the APIs change.
- Don’t use LLMs for autocomplete, use them for dialogues about the code. Tried that. It’s worse than a rubber duck, which at least knows to stay silent when it doesn’t know what it’s talking about.
The one place Copilot was vaguely useful was hinting at missing abstractions (if it can autocomplete big chunks then my APIs required too much boilerplate and needed better abstractions). The place I thought it might be useful was spotting inconsistent API names and parameter orders but it was actually very bad at this (presumably because of the way it tokenises identifiers?). With a load of examples with consistent names, it would suggest things that didn't match the convention. After using three APIs that all passed the same parameters in the same order, it would suggest flipping the order for the fourth.
#GitHubCopilot #CHERIoT
A wild #blog post appears.
A tutorial for setting up a cross compilation environment using FreeBSD/amd64 as the host and macOS/aarch64 as the target.
briancallahan.netLet's cross compile from FreeBSD/amd64 to macOS/aarch64 - Dr. Brian Robert Callahan
#Clang / #LLVM builds with almost no external dependencies (toolchain, cmake, and make). It builds an entire compiler and binutils.
#Rust build automatically pulls in and builds a ton of dependencies, but requires no user intervention. It builds the compiler and runtime libs.
#GCC build continues to suck
Hey #Haskell people, have any of you written a compiler with #Binaryen or #LLVM for the backend? Any recommendations on libraries, guides, or gotchas to watch out for?
I've seen the llvm-tf and llvm-ffi libraries which are reasonably current (each ~1 year since last update). I saw Tweag has a binaryen package, but I'm not sure they're updating it now that Asterius is defunct (~4 years since last update).
Had a bunch of thoughts about the recent safety stuff, way more than fit in social media post... Blog post story time! (It's a bit of a ramble, sorry about that...)
https://chandlerc.blog/posts/2024/11/story-time-bounds-checking/
chandlerc.blog · Story-time: C++, bounds checking, performance, and compilersRecently, several of my colleagues at Google shared the story of how we are
retrofitting spatial safety onto our monolithic C++ codebase:
https://security.googleblog.com/2024/11/retrofitting-spatial-safety-to-hundreds.html
I wanted to have a bit of story-time about some of the strange ways that all
this came to be, at least as I remember things. There are some really
interesting developments that led us here, and some important lessons to learn
from that history.
Do note that this is just my retrospective memory. It’s entirely possible I’m
misremembering some of it (let me know if so!). It’s also limited to my
perspective, and others may have seen very different aspects of things (please
share!).
Worked pretty hard on yet another KnownBits optimization for #LLVM yesterday: it took me almost 12 hours of working continuously to figure it out.
GitHubKnownBits: refine high-bits of mul in signed case by artagnon · Pull Request #113051 · llvm/llvm-project
Our #LLVM job ad is finally up!
We're looking to hire two people (probably one more senior, one more junior) to maintain, update, improve, and upstream the #CHERIoT LLVM toolchain (not necessarily in that order).
Happy to answer questions here.
www.scisemi.comCareersCHERIoT (CHERI) based microcontrollers and microprocessors target a range of cyber physical applications.
I really wish Alive2 had support for loop- based reasoning: the -src-unroll/-tgt-unroll doesn’t give me a guarantee. Struggling to reason about an #LLVM patch, and this isn’t the first time 