On: Faster remainders when the divisor is a constant: ...

[saagarjha]

This was exactly what I was about to mention; I can reproduce your results in Clang but it seems GCC doesn't want to optimize this? Here's what Godbolt gives me: https://godbolt.org/z/aFTdur

[acqq → saagarjha]

Just write a function “mydiv10” which returns if x < 99 { x /10 and 0 otherwise and try again.

[acqq → acqq]

Like this:

https://godbolt.org/z/bS2yzB

But also note that when the input is unsigned short we get:

https://godbolt.org/z/sbDbMU

        movzx   eax, di
        imul    eax, eax, 52429
        shr     eax, 19