Use #[inline] everywhere.#145
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I tried to follow the following rules for determining if something
should be #[inline]:
- Functions that are trivial. (E.g. implementations of `Add`, or a
trivial `new` function.)
- Functions that do not appear trivial, but would generate trivial
assembly. (E.g. functions with mostly Rust code that don't result much
generated code: `use` statements, wrapping values, bit twiddling,
`#[cfg]`, `PhantomData`, etc.)
- Functions that only call another function.
- Functions that could benefit a lot from inline optimization:
- Functions that have asserts/matches/ifs on the parameters, which are
likely constant or known to be in a certain range:
If a function starts with `assert!(param < 32)`, inlining enables
the compiler to completely optimize the check away if it already
knows the value to always be less than 32.
If a function matches on a parameter, inlining allows throwing all
but one match arm away.
- Functions where knowing the return value could benefit optimization on
later calls/code.
phil-opp
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Apr 11, 2020
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Thanks a lot for this! I have one small question about a removed inline, otherwise this looks good to me!
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I tried to follow the following rules for determining if something
should be #[inline]:
Add, or atrivial
newfunction.)assembly. (E.g. functions with mostly Rust code that don't result much
generated code:
usestatements, wrapping values, bit twiddling,#[cfg],PhantomData, etc.)likely constant or known to be in a certain range:
If a function starts with
assert!(param < 32), inlining enablesthe compiler to completely optimize the check away if it already
knows the value to always be less than 32.
If a function matches on a parameter, inlining allows throwing all
but one match arm away.
later calls/code.