Notices by John Regehr (regehr@mastodon.social)

@void_friend it's too bad that 99% of these C quizzes are more of "guess which UB the author means you to find" instead of "find the UB"

argh... I pretty recently switched from chrome to firefox on the two devices I use the most. what are we supposed to do now, dig up hotjava? lynx??

(and wow I just noticed that opera is still maintained. does anyone actually use it?)

https://securityonline.info/mozillas-new-terms-firefox-to-collect-user-data/

just a heads-up for anyone who works with an ABET-accredited university program: ABET is pathetic

https://info.abet.org/abet-important-message-from-abet-president-and-ceo

last Christmas my parents got us an air filter that we usually leave running now. it has an air quality sensor and it's incredible how fast it goes from "totally good" to "seriously shitty" when one of us runs a gas burner for a while. I mean, I knew it was bad, but ugh

@ricci @palvaro I don't remember that! must have been a long time ago. anyhow, I like Matt, or did some years ago when I last talked to him.

other day I was showing a student something on my machine and he got all quiet. I figured he was digesting the deep thoughts, then he says "so you really just use emacs all the time?"

someone on reddit did this

@andhow @snopes @torproject yesterday it was time to bail from X two years ago

@jrose @steve @porglezomp @bob there’s -Og now

C and C++ people: I'm looking for an example -- for a target the supports unaligned memory operations -- where code that violates language-level memory alignment requirements is *not* compiled into something that works as one would naively expect.

I vaguely remember people (almost certainly including @void_friend) discussing this some time ago, but I can't find the posts, argh

@jripley yeah! one of the blog posts I linked is that exact scenario

the CS:APP "bomb lab" has to be among the greatest computer science homework assignments ever developed. I'm releasing it to my students tomorrow. so fun!!!

http://csapp.cs.cmu.edu/3e/bomblab.pdf

hadn't realized how cheap they made getting the length of a C++ string_view

https://gcc.godbolt.org/z/EEfThbWY6

@lritter @Doomed_Daniel the fix isn’t defaults, the fix is proper abstraction of things that occur often so they are ready for easy reuse

when people mistake one of these for the other, we get spectacular problems such as the Python 2/3 debacle

the dilemma facing programming languages, as I see it, is that they fall into two categories:
- languages that can be rapidly and radically changed in response to problems (such as failures of abstraction) encountered in real use. but these are the languages without large load-bearing code bases, so they don't get many resources
- languages that have large, load-bearing code bases, which receive adequate engineering power, but not enough to overcome the legacy code problem

I said it in a reply thread but might as well repeat it here: the fix is languages that support proper abstraction of things that you do often, including design pattern sorta things

@erincandescent @atax1a @cr1901 but what this really means is that my LLVM backend bug hunting work should have focused on RISC-V, where the compiler has to try really hard. also, encoding the instructions would have been like 20% of the effort.

@erincandescent @atax1a @cr1901 I've been working pretty closely with AArch64 for a couple years and it's just a pleasure overall, it has the right bitfield operations, the right addressing modes, the immediate encodings are cute and useful, it's just fun. when I want to be annoyed I compare the codegen for a small C function in RISC-V vs. AArch64

what’s missing from the index for this textbook about low-level C programming?? 🤔