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scialex

41 karma · joined July 9, 2012

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scialex··on You can't fool the optimizer
This sort of pattern can't be found by incremental lowering (and isn't common enough to have more sophisticated analysis written for it) so it ends up in a local maximum.

Basically the idea for most compilers is to do a series of transforms which incrementally improve the program (or at least make it worse in understood and reversible ways). To do this transform you need the optimizer to do the (not always trivial) proof that the 2*x is equivalent to x+y, do the replacement, do the gvn to duplicate the adds and finally do the branch elimination. Each of these steps is however totally separate from one another and the first one doesn't trigger since as far as it's concerned a shift left is faster than an add so why should it do the replacement.

This is all even more complicated since what representation is faster can depend on the target.

scialex··on CLion Is Now Free for Non-Commercial Use
They are hoping that those companies will become like synopsys and able to sell per seat subscriptions to their software for huge amounts.

That or they just drank the Kool aid

scialex··on Meta antitrust trial kicks off in federal court
I mean it's not much more unreasonable then the argument that iphones and android phones don't compete but courts bought that.
scialex··on We need visual programming. No, not like that
The fact you can give things names means that there is rarely a need to follow the edges so the visualization is much less cluttered
scialex··on Ex-Googler says company's AI panic is like Google+ fiasco all over again
> Some of you may remember Google's much-hyped AI voice "Duplex," which was supposed to automate all those annoying phone calls and call centers. That was in 2018, six years ago. Since then, we've seen how it's turned out

Reasonably successfully?

Call screen is easily one of the best features of my phone. Call hold navigation is also really useful. It calling restaurants and the like is not something I commonly use but it works and I've used it sometimes.

scialex··on macOS 14.4 causes JVM crashes
It's not. It's trying to access unmapped or protected memory in its own process.

Basically what its used for is to implement an 'if' that's super fast on the most likely path but super slow on the less likely path.

It's not super clear what its being used for (this is often used for the GC but the fact that graal isn't affected means that likely still works). Possibly they are using this to detect attempts to use inline-cache entries that have been deleted.

scialex··on Morale plummets at Google as workers complain bosses are 'inept' and 'boring'
YouTube, Google maps, Gmail ...
scialex··on Reenix: Implementing a Unix-Like Operating System in Rust [pdf]
> what would be the "Rust way"?

I'm not sure there is one TBH.

scialex··on Reenix: Implementing a Unix-Like Operating System in Rust [pdf]
Thanks.

I believe HKT would have been useful but am not really sure how much HKT would have helped me overall. They would likely have been most useful (if at all) in the VFS/S5FS/VM stages that I was unable to fully get to.

Honestly, I have not used haskell enough to definitively say whether monads/arrows would have been useful.

scialex··on Reenix: Implementing a Unix-Like Operating System in Rust [pdf]
The actual kernel binary was smaller but the loader s limit was based on the amount of memory the kernel laid out in memory takes, including anonymous sections.

Also turning on optimizations in rust and the linker helped a lot but were not enough in the end.