Yesterday I was somehow frustrated because I could not use core::intrinsics::{likely,unlikely} on stable, and because it was difficult to use those compiler hints for refutable patterns. So I made a crate this morning which is almost a "hackery", to fix that:
-
it takes likely-hood-ness from i32::checked_div and then propagate it to a bool that is then used for branch selection.
-
The macro that provides
if_likely{let Some(v) = opt...actually performs the pattern matching twice but this should be cheap I suppose (the compiler optimize out the discriminant double check).
I have checked the assembly. It does work :).
There are details in the documentation obtained by cargo doc --features check_assembly --open => module check_assembly. There is a
demonstration on why #[cold] attribute cannot not be used.
Is there any charitable coder to review the code??