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thesz | 10 days ago

  > Assume FP64 units are ~2-4x bigger.

This is wrong assumption. FP64 usually uses the same circuitry as two FP32, adding not that much ((de)normalization, mostly).

From the top of my head, overhead is around 10% or so.

  > Why would gamers want to pay for any features they don't use?

Apparently FP80, which is even wider than FP64, is beneficial for pathfinding algorithms in games.

Pathfinding for hundredths of units is a task worth putting on GPU.

discuss

kbolino|10 days ago

Has FP80 ever existed anywhere other than x87?

The Motorola 88k and 68k both supported (eventually) extended precision, and, of course, Itanium supported it for x87 compatibility.

https://en.wikipedia.org/wiki/Motorola_88000 (under "Registers": "32 80-bit (88110 only)")

https://en.wikipedia.org/wiki/Extended_precision (see section titled "IEEE 754 extended-precision formats")