Fission

Debugging a decompilation failure

Last verified: 2026-05-02

Use this linear checklist before guessing at printer bugs.

1. Loader / facts (fission-loader)

Symptoms: CLI errors before listing functions, bogus sections, impossible addresses.

• Run fission_cli info + list on the smallest failing fixture (docs/EVALUATION.md).
• Fail-closed behavior is intentional (docs/adr/0003-fail-closed-loader-policy.md).

2. Disassembly sanity (fission_cli disasm)

Symptoms: wrong opcode stream at entry.

• Confirm function boundaries from list match bytes under disasm.
• If boundaries lie, fix loader/symbol pipeline—not NIR first.

3. Lift / pcode (fission-sleigh)

Symptoms: absurd pcode volume or decode aborts.

• Compare against sleigh references under vendor/ghidra/ conceptually—do not patch vendor copies for production fixes (docs/adr/0005-ghidra-reference-boundary.md).

4. NIR build (fission-pcode)

Symptoms: empty bodies, chaotic control flow, telemetry explosions.

• Inspect embedded counters via automation summaries (nir_build_stats_totals, docs/QUALITY_METRICS.md).
• Canonical counters live in crates/fission-pcode/src/nir/types.rs.

5. Structuring / normalization

Symptoms: duplicated labels, collapsed loops, odd regions.

• Fix in crates/fission-pcode/src/nir/structuring/ per child AGENTS.md.

6. Rendering

Symptoms: types look fine internally but pseudocode unreadable.

• Only after NIR/HIR matches intent should you tune printer.rs paths.

7. Regression scale-up

When the single function is understood:

cargo run -p fission-automation -- nir-check --lane nir --functions-limit 50 --no-build --fission-bin ./target/release/fission_cli

Attach benchmark/artifacts/automation/ excerpts to the PR if quality logic changed (CONTRIBUTING.md).

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