Hacker News: peterfirefly

New comment by peterfirefly in "Reviving Papers with Code"

peterfirefly — Wed, 10 Jun 2026 18:53:07 +0000

No, but I hate TLA overuse. Don't you?

"Are you a bot" is an obvious slur when it's easy to see for yourself that I'm not.

New comment by peterfirefly in "Branchless Quicksort faster than std:sort and pdqsort with C and C++ API"

peterfirefly — Sun, 07 Jun 2026 14:15:25 +0000

flohofwoe (above) and aw1621107 (next to this post) both figured out that the magic ingredient isn't whether we code an if or add the boolean value of a comparison to the array size. The magic ingredient is whether the store is conditional or not.

Having the compiler convert a conditional store to an unconditional store can have bad consequences if you have interrupts or task switches or SMP going on, so it's not a good idea to do it -- unless you can guarantee that the thread of execution the compiler can see is indeed the only one. Yeah, yeah, volatile and barriers etc... still, not a good idea.

New comment by peterfirefly in "Branchless Quicksort faster than std:sort and pdqsort with C and C++ API"

peterfirefly — Sun, 07 Jun 2026 13:56:50 +0000

I played a bit with your link. It depends on the compiler. x86_64 clang trunk indeed compiles the original first and your fixed second form to the exact same code. I tried a couple of msvc and gcc versions and they did not but they all made them both branchless.

New comment by peterfirefly in "Branchless Quicksort faster than std:sort and pdqsort with C and C++ API"

peterfirefly — Sun, 07 Jun 2026 13:45:23 +0000

The latter only adds small numbers to the small_numbers[] array.

The former preliminarily adds all numbers to the array but only keeps the small ones.

As long as you don't look at the small_numbers[smlen] element after the loop, they behave identically.

New comment by peterfirefly in "Branchless Quicksort faster than std:sort and pdqsort with C and C++ API"

peterfirefly — Sun, 07 Jun 2026 13:42:38 +0000

The Linux kernel had problems years ago when gcc started to do exactly that in certain cases (because it screwed things up with task switches, interrupts, and SMP). It fairly quickly afterwards either stopped doing it entirely or got a switch that would stop it from doing it. Don't remember which.

New comment by peterfirefly in "Changing how we develop Ladybird"

peterfirefly — Sun, 07 Jun 2026 13:28:16 +0000

What if the degree doesn't really help with that?

New comment by peterfirefly in "Changing how we develop Ladybird"

peterfirefly — Sun, 07 Jun 2026 13:27:49 +0000

Far longer. It was never needed. Skills were needed. How they were gained had no effect on what people could or couldn't do.

New comment by peterfirefly in "Moving beyond fork() + exec()"

peterfirefly — Sun, 07 Jun 2026 01:04:42 +0000

Did you mean over-estimated?

New comment by peterfirefly in "Moving beyond fork() + exec()"

peterfirefly — Sun, 07 Jun 2026 00:12:33 +0000

No.

https://en.wikipedia.org/wiki/Windows_NT#Development

Windows NT was developed on various different CPUs before the Alpha was a thing. When it was released in 1993, it was released for three CPUs: IA-32, MIPS, and Alpha.

New comment by peterfirefly in "I'm skeptical about efforts to revolutionize schooling"

peterfirefly — Fri, 05 Jun 2026 13:08:01 +0000

reading skills are important.

New comment by peterfirefly in "I'm skeptical about efforts to revolutionize schooling"

peterfirefly — Fri, 05 Jun 2026 13:06:55 +0000

closer to 12 than to 15.

New comment by peterfirefly in "Delacroix's Entry of the Crusaders into Constantinople Restored"

peterfirefly — Fri, 05 Jun 2026 10:20:54 +0000

The fourth crusade was an utter disaster for Europe/The Middle East/Christendom.

Some of the others were indeed great and something like that and the Reconquista do indeed sound overdue. Can we do that without repeating the fourth?

New comment by peterfirefly in "Failing grades soar with AI usage, dwindling math skills in Berkeley CS classes"

peterfirefly — Thu, 04 Jun 2026 22:51:13 +0000

I think IQ tests are even better.

New comment by peterfirefly in "CP/M-86 & MS-DOS Cross Development Environment"

peterfirefly — Thu, 04 Jun 2026 11:19:17 +0000

They used it at my high school in Denmark. It was easy to share hard disks across many machines and the ability to multitask was also very nice. The office people could switch between word processing and calendar software easily, for example.

New comment by peterfirefly in "QBE – Compiler Backend – 1.3"

peterfirefly — Tue, 02 Jun 2026 22:31:49 +0000

More like no inlining, so-so register allocation, and a simple code generator. I believe also no loop unrolling. Other compilers could handle the table-less CRC implementation.

New comment by peterfirefly in "QBE – Compiler Backend – 1.3"

peterfirefly — Tue, 02 Jun 2026 22:24:33 +0000

I tried to look at the QBE code years ago while I was writing my own SSA code. I got approximately nowhere because I can't read code like that. Turns out that reading the SSA papers and writing the code was a lot easier than reading QBE.

New comment by peterfirefly in "QBE – Compiler Backend – 1.3"

peterfirefly — Tue, 02 Jun 2026 21:44:18 +0000

clearly the latter.

New comment by peterfirefly in "Netherlands blocks US takeover of vital digital supplier"

peterfirefly — Tue, 26 May 2026 20:29:52 +0000

It sounds a bit like "giro" which was a physical mail-based way of transferring money. Not a bad name at all.

New comment by peterfirefly in "Performance of Rust Language [pdf]"

peterfirefly — Tue, 26 May 2026 20:22:05 +0000

On Windows? Use a dev drive.

New comment by peterfirefly in "Performance of Rust Language [pdf]"

peterfirefly — Tue, 26 May 2026 20:19:42 +0000

You can sometimes just add asserts for the index variable(s) and have the LLVM optimizer go "hmm, I should try to prove that those are true" and then get the range checks optimized away.