Notices by John Regehr (regehr@mastodon.social)

@andrewrk hand twins!!

the prettiest arrowhead I ever found in Utah!

@lzg Sarah and I like to watch Silo and every single episode we say "it's too dark" and "turn on subtitles I can't hear anything"

@dalias @Sobex @dave_andersen @va2lam @zwol @chipchristian yeah I imagine that at present, a lot of code works only due to separate compilation

@dalias @Sobex @dave_andersen @va2lam @zwol @chipchristian ah, no problem then!

@dalias @Sobex @dave_andersen @va2lam @zwol @chipchristian I thought effective type was conferred when you first store to the typeless memory, and remains the same after that

@dalias @Sobex @dave_andersen @va2lam @zwol @chipchristian ah, super cool. not something I can verify with quick inspection :).

but then eventually, memory is going to be repurposed, for example when you split a block that has already been used by the client. in that case we're just relying on separate compilation, I suppose?

@Sobex @dave_andersen @va2lam @zwol @chipchristian hey @dalias -- I just took a super quick look at MUSL's mallocng and it seems to be dereferencing typecast pointers in ways that might violate strict aliasing. do you mind telling us why this isn't a problem? maybe you insist that this is compiled with strict aliasing disabled?

an undergrad was in my office today and I suggested that instead of trying to coax clang and opt into giving him the LLVM IR that he wants for some test cases, he should just write it by hand. "really, just raw dog the LLVM IR?" he responded

absolutely indefensible code. I mailed them about this years and years ago

https://gcc.godbolt.org/z/W3jdEdnn4

@uecker reminded me that this C23 feature is a better choice than the intrinsic, and also results in optimal codegen https://gcc.godbolt.org/z/xP3reE9n8

switching over to codegen for overflow checking for addition, we don't appear to get optimal code for any of the obvious ways to do it, from latest GCC or LLVM, unless we use the intrinsic

https://gcc.godbolt.org/z/9bcPdzYcY

Computer Systems: A Programmer’s Perspective, a textbook by Bryant and O’Halloran, is in its third edition and also its third decade of teaching students falsehoods about C

totally agree with this and there are SO many examples of tools where 99% of uses are adapting an existing program/config file instead of creating a new one from scratch

https://blog.yossarian.net/2025/01/10/Be-aware-of-the-Makefile-effect

like think about the last time you started a LaTeX document from a blank file...

@whitequark say what

@whitequark dmr's machine had /etc and /bin on different disks and one of them was full

sure hope we don't have to read about bro in the news in a few months

@lzg 2015 called, wants its terrorists back

"Advent of Code 2024 in pure SQL"

I like pieces like they because they really underscore the fact that like 90% of programming is figuring out what needs to be done and 10% is actually making it happen

https://databasearchitects.blogspot.com/2024/12/advent-of-code-2024-in-pure-sql.html

@lzg true, true