perf(lexer): hint to compiler that EOF only happens once #15512
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Pull Request Overview
This PR applies a performance optimization to the lexer's EOF handling by using a #[cold] attribute to hint to the compiler that the EOF branch is rarely taken, potentially improving branch prediction for the hot path.
- Wraps the EOF return in a
#[cold]function to optimize branch prediction
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In `Lexer::read_next_token`, reaching EOF is very uncommon (because it only happens once at end of the file). Inform compiler of this using a `#[cold]` function, so it makes "not at EOF" the default path. Small improvement on all the lexer and parser benchmarks (+1% on most lexer benchmarks).
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In `Lexer::read_next_token`, reaching EOF is very uncommon (because it only happens once at end of the file). Inform compiler of this using a `#[cold]` function, so it makes "not at EOF" the default path. Small improvement on all the lexer and parser benchmarks (+1% on most lexer benchmarks).
In
Lexer::read_next_token, reaching EOF is very uncommon (because it only happens once at end of the file). Inform compiler of this using a#[cold]function, so it makes "not at EOF" the default path.Small improvement on all the lexer and parser benchmarks (+1% on most lexer benchmarks).