kornia/kornia-rs

[Perf]: Investigate restoring opt-level=3 for aarch64 cross-compilation

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#682 opened on Jan 28, 2026

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Description

Title: Investigate restoring opt-level=3 for aarch64 cross-compilation

Description

We currently override the optimization level for the aarch64-unknown-linux-gnu target to 2 in our cargo configuration:

[target.aarch64-unknown-linux-gnu]
rustflags = ["-Copt-level=2", "-Ctarget-feature=+fp16,+fhm"]

This workaround was introduced to bypass a compiler segfault (SIGSEGV) in LLVM's BranchProbabilityInfo pass when compiling the faer dependency with opt-level=3.

Downgrading to opt-level=2 potentially leaves performance on the table for our ARM builds (e.g., Jetson devices), which is critical for this project.

Goal

Determine if this workaround is still necessary with the latest stable rustc version.

Task

  1. Attempt to remove the -Copt-level=2 flag (reverting to the default or explicit 3).
  2. Cross-compile the project for aarch64-unknown-linux-gnu.
  3. If the build succeeds without crashing, benchmark the artifacts to verify performance gains and ensure runtime stability.
  4. If it still crashes, document the current rustc version and the specific LLVM error trace for upstream reporting.

Contributor guide

Research direction
Remove the Copt level=2 flag from the cargo configuration for aarch64 unknown linux gnu, cross compile the project, and verify whether the build succeeds without segfault. If successful, benchmark the artifacts to measure performance improvement. If it crashes, document the current rustc version and the LLVM error trace for upstream reporting.
Tech stack
rust
Domain
compilers
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50