# Objective
In #11330 I found out that `Parent::get` didn't get inlined, **even with
LTO on**!
This means that just to access a field, we have an instruction cache
invalidation, we will move some registers to the stack, will jump to new
instructions, move the field into a register, then do the same dance in
the other direction to go back to the call site.
## Solution
Mark trivial functions as `#[inline]`.
`inline(always)` may increase compilation time proportional to how many
time the function is called **and the size of the function marked with
`inline`**. Since we mark as `inline` functions that consists in a
single instruction, the cost is absolutely negligible.
I also took the opportunity to `inline` other functions. I'm not as
confident that marking functions calling other functions as `inline`
works similarly to very simple functions, so I used `inline` over
`inline(always)`, which doesn't have the same downsides as
`inline(always)`.
More information on inlining in rust:
https://nnethercote.github.io/perf-book/inlining.html
a634075a39