bevy/crates/bevy_hierarchy
Nicola Papale a634075a39
Inline trivial methods in bevy_hierarchy (#11332)
# 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
2024-01-13 22:20:50 +00:00
..
src Inline trivial methods in bevy_hierarchy (#11332) 2024-01-13 22:20:50 +00:00
Cargo.toml Re-export smallvec crate from bevy_utils (#11006) 2023-12-24 15:35:09 +00:00