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by chrisseaton 1540 days ago
> I guess on intel architectures the compiler just calls the fsin instruction of the cpu.

Do people do that in practice? It's on the FPU, which is basically legacy emulated these days, and it's inaccurate.

1 comments

> the FPU, which is basically legacy

you'll pry my long doubles from my cold, dead hands!

The question is if you wouldn't be better served with double-doubles today. You get ~100 bits of mantissa AND you can still vectorize your computations.
Sure. There should be a gcc flag to make "long double" become quadruple precision.

The thing is, my first programming language was x86 assembler and the fpu was the funniest part. Spent weeks as a teenager writing almost pure 8087 code. I have a lot of emotional investment in that tiny rolling stack of extended precision floats.

How is "quad floating point" implemented on x86? Is it software emulation?
You're selectively quoting me - I said it's 'legacy emulated'. It's emulated using very long-form microcode, so basically emulated in software. I didn't say it was simply 'legacy'.
I’m completely out of my depth reading through these comments so I don’t have much of value to contribute, but I do think I can gently say I think the selective quoting was harmless, but deliberate to fit the shape of a harmless joke’s setup. I don’t think there was any intent to misrepresent your more salient information.