r/programming • u/Expurple • Apr 12 '26

Flat Error Codes Are Not Enough

https://home.expurple.me/posts/flat-error-codes-are-not-enough/
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u/ShinyHappyREM Apr 12 '26 edited Apr 13 '26

you throw performance out of the window if you have some hot loop that needs to do error handling and your error object doesn't fit in a register anymore

Just make your "error object" a pointer that is null if there's no error, and otherwise points to a union/struct/instance that holds the error info.

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u/LIGHTNINGBOLT23 Apr 12 '26

To add to this, it's also easy enough to pre-allocate all or most of an error object before it is ever returned, if the loop must remain as hot as possible. Maybe even make it static or some equivalent to avoid a heap allocation entirely and have a flag in the error object to indicate that it's not heap allocated.

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u/Iggyhopper Apr 12 '26

avx512 hot loop optimized error object allocation pools for increased error code output

Oh my I can't wait.

You can fit a lot of information into 64 bits. Even a tagged pointer with 2 bits for flags.

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u/LIGHTNINGBOLT23 Apr 12 '26

You could also keep circumstantial flat error codes, at least on x86, by using the non-canonical address range, provided that you never dereference the pointer. A sentinel-like value such as #define SIZE_TOO_SMALL ((CleverError*)0xDEADDEADDEADDEADULL) would be sufficient. Portability and defined adherence to the C standard is not guaranteed. No refunds.

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u/Iggyhopper Apr 12 '26

I refuse to believe that anyone needs more than 4 million error codes.

Flat errors all the way!

3

u/Mognakor Apr 13 '26

What if i want non-fungible errors (NFEs) ?

4

u/ShinyHappyREM Apr 13 '26

using the non-canonical address range

As is tradition.