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by flohofwoe 862 days ago
...which is a bit of a weak reason when there are hardly any 32-bit CPUs around anymore though. Picking a narrower integer type makes sense in specific situations like tightly packed structs, but in that case it usually doesn't matter whether the integer range is 2^31 or 2^32, if you really need the extra bit of range it's usually ok to go to the next wider integer type.
2 comments
jusuhi 862 days ago
Feel free to generalize my argument to i31 and i15.

Also, look around you and realize that non-64-bit microprocessors outnumber 64-bit machines by orders of magnitude. There is more to the world than your laptop and smartphone. (Just within 1m of myself at this very moment I see 4 devices with a 32 bit microprocessor in them, and I'm sitting in a coffee shop reading a book. Well, and browsing HN now and then.)

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flohofwoe 862 days ago
There's actually a better solution if you allow the compiler some wiggle room:

Zig and C23 (and probably a couple other languages) support arbitrary width integers, so integer types like u15, i3, i1 or even u512 etc... are something entirely 'normal', and even useful in day-to-day coding when mixing signed and unsigned integer math (for instance Zig disallows to assign an unsigned integer to a signed integer of the same width, but it's perfectly fine to assign a 7-bit unsigned integer to an 8-bit signed integer).

Down on the CPU such operations happen on the register width, and if the integer width exceeds the register width, are unrolled into a chain of op-with-carry instructions (same way we did 16- or 32-bit math back on 8-bit processors).

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saagarjha 862 days ago
Surely your laptop and smartphone have several 32-bit microprocessors in them.
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Findecanor 862 days ago
Pretty much all "64-bit" CPU architectures out there also have specific instructions for 32-bit arithmetic.

They were designed that way partly on purpose, to cater for the enormous amount of existing program code that has been written with the assumption that an `int` is 32 bits. A large portion of that code also written with the assumption that they are also 2's complement and wrapping.

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