miri-dsp

name	miri-dsp
description	Run `cargo +nightly miri test` against a Rust DSP crate to detect undefined behaviour the compiler missed — out-of-bounds access, use-after-free, uninitialised memory reads, invalid pointer arithmetic. Miri is the cheapest sound UB detector for Rust; this skill wraps it with the right isolation flags for audio DSP crates.
allowed-tools	Bash
argument-hint	<crate-path>

Miri DSP

miri interprets Rust's mid-level IR and catches a large class of undefined behaviour that cargo test will silently miss: out-of-bounds slice access, use-after-free, reads of uninitialised memory, invalid unsafe pointer arithmetic, and aliasing violations under the Stacked Borrows / Tree Borrows models.

Miri is most valuable on no_std DSP crates — they tend to contain hand-written unsafe for SIMD and ringbuffers where the compiler cannot prove safety. The cost is runtime speed (Miri is an interpreter, not a compiler), so this skill targets the unit tests of a single crate rather than a whole workspace.

Limitations

• Miri does not target wasm32. It runs on the host triple. UB-free under Miri does not guarantee UB-free under wasm32 — but in practice the UB classes Miri catches are target-independent.
• Floating-point intrinsics are slow under Miri. Heavy DSP benchmark suites will time out. Focus tests on correctness invariants and unsafe boundaries, not on full audio renders.
• cargo bench does not run under Miri — use the cargo-bench-rt skill on native instead.

Requirements

• Rust nightly toolchain with the miri component:

  rustup toolchain install nightly
  rustup +nightly component add miri
  

The script bootstraps both if missing.

Instructions

The argument is in $ARGUMENTS. Pass it directly to the run script:

bash "$(dirname "$0")/run.sh" $ARGUMENTS

The argument is the path to the crate directory.

Output sections

Section	What it reports
TOOLCHAIN	Whether nightly + miri are installed
MIRI	Result of cargo +nightly miri test

Typical usage

# Run miri on a single DSP crate
bash run.sh ./rust/audio-dsp

# Run on every DSP crate in a workspace
for crate in rust/dsp-*; do bash run.sh "$crate"; done

What to look for

• MIRI failing with "Undefined Behavior" — read the report carefully. Miri pinpoints the exact statement and explains the violation (e.g. "reading uninitialised bytes", "out-of-bounds pointer offset", "stacked borrows violation").
• MIRI timing out — narrow the test set. Mark long-running renders with #[cfg(not(miri))] so they are skipped under Miri while still running under cargo test.
• MIRI reporting "unsupported operation" — Miri does not support every libc or syscall. If the offending call is in a third-party dep, gate that path behind a feature flag the DSP crate does not enable; if it is in your own code, the operation probably should not be in a DSP crate at all.

How often to run

Run on every change to an unsafe block in a DSP crate. Optional but valuable in CI on a nightly schedule.