dtolnay/cxx

Figure out where to put #[inline]

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#146 opened on Apr 25, 2020

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help wanted

Description

In the Rust code generator we currently emit some shims that do nothing more than cast between smart pointers and raw pointers and then dispatch to the appropriate extern "C" function.

These shims should probably be marked #[inline] so that callers are able to directly call the extern "C" function themselves, but ideally I'd like at least one performance measurement showing a benefit before going forward with the change.

Contributor guide

Tech stack
rust
Domain
performance
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
basic Rustfamiliarity with cxx code generator
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Investigate the Rust code generator in the cxx crate to locate the shim functions that cast between smart pointers and raw pointers. Implement a benchmark to measure the performance difference with and without #[inline] annotations on these shims. Report the results in the issue to support the decision to add #[inline].