27 lines
1.3 KiB
Markdown
27 lines
1.3 KiB
Markdown
## PHI-off Troubleshooting
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Scope: MIR PHI-off (edge-copy) policy with LLVM harness PHI synthesis.
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Symptoms and Hints
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- Merge block contains self-copy to merged value
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- Symptom: Verifier (edge-copy strict) complains or trace shows unexpected write at merge.
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- Check: Enable `NYASH_VERIFY_EDGE_COPY_STRICT=1` and locate offending merge block.
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- Fix: Ensure copies are inserted in predecessors only; merge binds the already-defined dst.
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- Missing predecessor copy into merged destination
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- Symptom: Edge-copy strict reports missing pred; phi-trace checker shows `missing=[...]`.
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- Check: `tools/phi_trace_check.py --file <trace.jsonl> --summary` (or drop `--summary` to see diffs on error).
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- Fix: Builder/Bridge must insert `Copy{dst=merged}` at that predecessor end.
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- Synthesized zero in PHI wiring
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- Symptom: phi-trace shows `zero=1` or checker with `--strict-zero` fails.
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- Check: Ensure the source value exists at predecessor end (resolve_i64/snapshot); add casts/boxing at pred end.
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- Fix: Route casts at pred end (not at merge); for strings/handles, ensure i64 handle flows across blocks.
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Tools
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- JSON trace: set `NYASH_LLVM_TRACE_PHI=1` and `NYASH_LLVM_TRACE_OUT=<path>`
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- One-shot: `tools/phi_trace_run.sh <app.nyash> [--strict-zero]`
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- Strict verifier (PHI-off): `NYASH_VERIFY_EDGE_COPY_STRICT=1 cargo test --lib`
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