Chris Fallin

547 Followers
302 Following
531 Posts
Nerd-of-all-trades, happiest when hacking deep innards of a compiler or runtime.
wwwhttps://cfallin.org/
whereaboutssunnyvale, california (SF bay area)
pronounshe/him
affiliationcurrently software engineer @ F5; previously Fastly, Mozilla, PhD @ CMU ECE, Google, Intel
"It takes a long time to say anything in Old Assembler," intoned Greybeard, "so we do not say anything unless it is very important."
A few years ago I designed a way to detect bit-flips in Firefox crash reports and last year we deployed an actual memory tester that runs on user machines after the browser crashes. Today I was looking at the data that comes out of these tests and now I'm 100% positive that the heuristic is sound and a lot of the crashes we see are from users with bad memory or similarly flaky hardware. Here's a few numbers to give you an idea of how large the problem is. 🧵 1/5
@guenther @gabrielesvelto ah yes, bitflips georg who lives in a plutonium mine and gets a thousand bit-flip related crashes every day is an outlier adn should not have counted

When AI Writes the World’s Software, Who Verifies It?

https://leodemoura.github.io/blog/2026/02/28/when-ai-writes-the-worlds-software.html

"Writing a specification forces clear thinking about what a system must do, what invariants it must maintain, what can go wrong. This is where the real engineering work has always lived. Implementation just used to be louder."

When AI Writes the World's Software, Who Verifies It?

Leonardo de Moura — Creator of Lean and Z3

while we're at it, let's make sure everyone has read the audiophile memcpy post

https://www.audioasylum.com/messages/pcaudio/119979/

RE: A revolution in audio rendering - SBGK - Computer Audio Asylum

RE: A revolution in audio rendering - SBGK - Computer Audio Asylum

in 2017 a popular twitter game was to type a partial phrase then see what your phone auto-completes it with.

this proved so popular that it is now the only business model in the US.

You don't use open source software because it's better (it usually isn't).

You don't use open source software because it's freer (it only sometimes is).

You don't use open source software because it's got better politics (it isn't always).

You use open source software because *it is the only option*. In the long run, if it isn't open source, it doesn't exist.

image source: keithstack.com

combined Davos/POPL keynote ideas

"You'll own nothing and you'll be happy: a garbage collection rejoinder"
"The great shift/reset: a continuation or delimiter of progress?"
"Late-staged programming: are the economics of macros sustainable?"

Scheme, the ur programming language, is 50 years old, as Jason Hemann just reminded me.

I hereby coin the term "Ptolemaic Code" to refer to software that appears functional but is based on a fundamentally incorrect model of the problem domain. As more code is generated by AI, the prevalence of such code is likely to increase.
1/7

#TheGeneralTheoryOfSlop