Optimize string handling in lit_token(). #50525
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r? @pnkfelix (rust_highfive has picked a reviewer for you, use r? to override) |
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| // new symbol because the string in the LitKind is different to the | ||
| // string in the Token. | ||
| let s = &sym.as_str(); | ||
| if s.contains('\\') || s.contains('\r') { |
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Since we are already micro-optimizing: This will iterate the string twice. Something like the following might be faster:
if s.as_bytes().iter().any(|&c| c == b'\\' || c == b'\r') {
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Looks good to me. |
In the common case, the string value in a string literal Token is the same as the string value in a string literal LitKind. (The exception is when escapes or \r are involved.) This patch takes advantage of that to avoid calling str_lit() and re-interning the string in that case. This speeds up incremental builds for a few of the rustc-benchmarks, the best by 3%.
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I updated to include @michaelwoerister's suggestion. |
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@bors r+ Thanks, @nnethercote! |
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📌 Commit 65ea0ff has been approved by |
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…rister
Optimize string handling in lit_token().
In the common case, the string value in a string literal Token is the
same as the string value in a string literal LitKind. (The exception is
when escapes or \r are involved.) This patch takes advantage of that to
avoid calling str_lit() and re-interning the string in that case. This
speeds up incremental builds for a few of the rustc-benchmarks, the best
by 3%.
Benchmarks that got a speedup of 1% or more:
```
coercions
avg: -1.1% min: -3.5% max: 0.4%
regex-check
avg: -1.2% min: -1.5% max: -0.6%
futures-check
avg: -0.9% min: -1.4% max: -0.3%
futures
avg: -0.8% min: -1.3% max: -0.3%
futures-opt
avg: -0.7% min: -1.2% max: -0.1%
regex
avg: -0.5% min: -1.2% max: -0.1%
regex-opt
avg: -0.5% min: -1.1% max: -0.1%
hyper-check
avg: -0.7% min: -1.0% max: -0.3%
```
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Rollup of 11 pull requests Successful merges: - #49988 (Mention Result<!, E> in never docs.) - #50148 (turn `ManuallyDrop::new` into a constant function) - #50456 (Update the Cargo submodule) - #50460 (Make `String::new()` const) - #50464 (Remove some transmutes) - #50505 (Added regression function match value test) - #50511 (Add some explanations for #[must_use]) - #50525 (Optimize string handling in lit_token().) - #50527 (Cleanup a `use` in a raw_vec test) - #50539 (Add more logarithm constants) - #49523 (Update RELEASES.md for 1.26.0) Failed merges:
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In the common case, the string value in a string literal Token is the
same as the string value in a string literal LitKind. (The exception is
when escapes or \r are involved.) This patch takes advantage of that to
avoid calling str_lit() and re-interning the string in that case. This
speeds up incremental builds for a few of the rustc-benchmarks, the best
by 3%.
Benchmarks that got a speedup of 1% or more: