Hackers' Pub

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`"` keyword `"`	Finds the string within quotes, including spaces. Case-insensitive. (Escape quotes inside with `\"`)	`"Hackers' Pub"`
`from:` handle	Finds content written by the specified user.	`from:hongminhee` `from:hongminhee@hollo.social`
`lang:` ISO 639-1	Finds content written in the specified language.	`lang:en`
`#` tag	Finds content with the specified tag. Case-insensitive.	`#HackersPub`
condition condition	Finds content that satisfies both conditions on either side of the space (logical AND).	`"Hackers' Pub" lang:en`
condition `OR` condition	Finds content that satisfies at least one of the conditions on either side of the OR operator (logical OR).	`#HackersPub OR "Hackers' Pub" lang:en`
`(` condition `)`	Combines the operators within the parentheses first.	`(#HackersPub OR "Hackers' Pub" OR "Hackers Pub") lang:en`

Brian Swetland @swetland@chaos.social

2/17/2026, 6:03:32 AM

Public

The attitude of modern compiler maintainers toward "undefined behavior" really drives me nuts. Here's a 2015 paper on the subject that explores why far more patiently and politely than I am able to...

https://www.complang.tuwien.ac.at/kps2015/proceedings/KPS_2015_submission_29.pdf

What every compiler writer should know about programmers
or
“Optimization” based on undefined behaviour hurts performance
M. Anton Ertl⋆
TU Wien

Abstract.
In recent years C compiler writers have taken the attitude
that tested and working production (i.e., conforming according to the
C standard) C programs are buggy if they contain undefined behaviour,
and they feel free to compile these programs (except benchmarks) in a
way that they no longer work. The justification for this attitude is that it
allows C compilers to optimize better. But while these “optimizations”
provide a factor 1.017 speedup with Clang-3.1 on SPECint 2006, for
non-benchmarks it also has a cost: if we go by the wishes of the compiler
maintainers, we have to “fix” our working, conforming C programs; this
requires a substantial effort, and can result in bigger and slower code.
The effort could otherwise be invested in source-level optimizations by
programmers, which can have a much bigger effect (e.g., a factor > 2.7
for Jon Bentley’s traveling salesman program). Therefore, optimizations
that assume that undefined behaviour does not exist are a bad idea
not just for security, but also for the performance of non-benchmark
programs.

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