docs(lexer): update doc comment about perf benefit of reading through references#21423
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Pull request overview
Updates a lexer hot-path doc comment to replace outdated stdlib source links with a more current explanation of why ptr.as_ref().unwrap_unchecked() can outperform raw pointer dereferencing.
Changes:
- Removes stale links to specific
core::slice::itersource locations. - Expands the comment to explain the likely LLVM IR benefit (e.g.,
nonnull/dereferenceableon&u8) and why this can help optimize hot loops.
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… references (#21423) Doc comments only change. I wrote this code 2 years ago, and had little idea then why `ptr.as_ref().unwrap_unchecked()` was so much faster than `*ptr`. The comment here was a rather half-baked explanation, likely inaccurate, and the references in the comment to stdlib's code that I made at the time are now outdated and therefore uninformative. Update the comment with a better explanation of the likely reason for the performance difference. It's still somewhat guesswork, but a more informed guess now at least.
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### 💥 BREAKING CHANGES - 24fb7eb allocator: [**BREAKING**] Rename `Box` and `Vec` methods (#21395) (overlookmotel) ### 🚀 Features - ce5072d parser: Support `turbopack` magic comments (#20803) (Kane Wang) - f5deb55 napi/transform: Expose `optimizeConstEnums` and `optimizeEnums` options (#21388) (Dunqing) - 24b03de data_structures: Introduce `NonNullConst` and `NonNullMut` pointer types (#21425) (overlookmotel) ### 🐛 Bug Fixes - d7a359a ecmascript: Treat update expressions as unconditionally side-effectful (#21456) (Dunqing) - 56af2f4 transformer/async-to-generator: Correct scope of inferred named FE in async-to-generator (#21458) (Dunqing) - b3ed467 minifier: Avoid illegal `var;` when folding unused arguments copy loop (#21421) (fazba) - b0e8f13 minifier: Preserve `var` inside `catch` with same-named parameter (#21366) (Dunqing) - 4fb73a7 transformer/typescript: Preserve execution order for accessor with `useDefineForClassFields: false` (#21369) (Dunqing) ### ⚡ Performance - da3cc16 parser: Refactor out `LexerContext` (#21275) (Ulrich Stark) ### 📚 Documentation - c5b19bb allocator: Reformat comments in `Arena` (#21448) (overlookmotel) - 091e88e lexer: Update doc comment about perf benefit of reading through references (#21423) (overlookmotel) - 922cbee allocator: Remove references to "bump" from comments (#21397) (overlookmotel) Co-authored-by: Dunqing <29533304+Dunqing@users.noreply.github.com>
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Doc comments only change.
I wrote this code 2 years ago, and had little idea then why
ptr.as_ref().unwrap_unchecked()was so much faster than*ptr. The comment here was a rather half-baked explanation, likely inaccurate, and the references in the comment to stdlib's code that I made at the time are now outdated and therefore uninformative.Update the comment with a better explanation of the likely reason for the performance difference. It's still somewhat guesswork, but a more informed guess now at least.