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Irenes (many)ireneista@irenes.space
Sep 16, 2026, 9:25 PM
@mcc @hyc we have a gamedev friend and a platform ABI friend who are always teasing each other about the other party stealing their pointer bits
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Irenes (many)ireneista@irenes.space
Sep 16, 2026, 9:26 PM
@mcc @hyc we definitely think it's less common than it used to be for language runtimes in languages that aren't made by OS vendors, perhaps due to portability concerns, but we can attest for certain that it is still a thing that happens
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Irenes (many)ireneista@irenes.space
Sep 16, 2026, 9:28 PM
@mcc @hyc we are not ourselves experts on it, we do find it very easy to believe that it has hidden costs
it's just that if your goal either involves a very high level of vertical integration, or is a very tightly focused single-purpose thing, that can be mitigated
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David SmithCatfish_Man@mastodon.social
Sep 16, 2026, 9:35 PM
@ireneista @mcc @hyc *waves* :)
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Irenes (many)ireneista@irenes.space
Sep 16, 2026, 9:36 PM
@Catfish_Man @mcc @hyc hi! yeah we weren't sure whether to @ you :3
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Nathan Vander Wiltnatevw@toot.cafe
Sep 17, 2026, 1:48 AM
@Catfish_Man @ireneista @mcc @hyc yeah was gonna mention Obj-C and presumably Swift over on @MaddieM4 part of the thread. I remember you and @gparker squeezing a lot into/out of object pointers back in the day! https://mikeash.com/pyblog/friday-qa-2017-06-30-dissecting-objc_msgsend-on-arm64.html
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Greg Parkergparker@discuss.systems
Sep 17, 2026, 2:40 AM
@natevw @Catfish_Man @ireneista @mcc @hyc @MaddieM4 Now @mikeash is in charge of the pointer bit stealing in the Objective-C and Swift runtimes. I moved over to kernel security, currently stealing pointer bits inside the virtual memory metadata.
The recent increase in RAM prices has made these tricks even more commercially relevant, unfortunately.
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mikeashmikeash@mastodon.sdf.org
Sep 17, 2026, 4:40 AM
@gparker @natevw @Catfish_Man @ireneista @mcc @hyc @MaddieM4 There are places where I would do unspeakable things just to have a few more spare bits in a pointer.
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