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Comment by crote | Hacker News Reader

The problem is that your "good enough" is someone else's "woefully inadequate", and sticking to the old feature sets is going to make the software horribly inefficient - or just plain unusable.

I'm sure there's someone out there who believe their 8086 is still "good enough", so should we restrict all software to the features supported by an 8086: 16-bit computations only, 1 MB of memory, no multithreading, no SIMD, no floats, no isolation between OS and user processes? That would obviously be ludicrous.

At a certain point it just doesn't make any sense to support hardware that old anymore. When it is cheaper to upgrade than to keep running the old stuff, and only a handful of people are sticking with the ancient hardware for nostalgic reasons, should that tiny group really be holding back basically your entire user base?

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Ah, com'on, spare me from these strawman arguments. Good enought is good enough. If F-Droid wasn't worried about that, you definitely have no reasons to do that for them.

"A tiny group is holding back everyone" is another silly strawman argument - all decent packaging/installation systems support providing different binaries for different architectures. It's just a matter of compiling just another binary and putting it into a package. Nobody is being hold back by anyone, you just can't make a more silly argument than that...

But it isn't good enough. SIMD provides measurable improvements to some people's code. To those people what we had before isn't good enough. Sure for the majority SIMD provides no noticeable benefit and so what we had before is good enough, but that isn't everybody.

Are you SURE that nobody has figured out how to have code that uses SIMD if you have it, and not use it if you don't?

Your suggestion falls flat on its face when you look at software where performance REALLY matters: ffmpeg. Guess what? It'll use SIMD, but can compile and run just fine without.

I don't understand people who make things up when it comes to telling others why something shouldn't be done. What's it to you?

It definitely is, you can even do that automatically with SIMDe and runtime function selection.

https://wiki.debian.org/InstructionSelection

ffmpeg is a bad example, because it's the kind of project that has lots of infrastructure around incorporating hand-optimized routines with inline assembly or SIMD intrinsics, and runtime detection to dispatch to different optimized code paths. That's not something you can get for free on any C/C++ code base; function multiversioning needs to be explicitly configured per function. By contrast, simply compiling with a newer instruction set permits the compiler's autovectorization use newer instructions whenever and wherever it finds an opportunity.

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