hakorune/docs/private/papers/paper-a-mir13-ir-design/SCOPE.md

Scope & Assumptions (2025-09-19)

Current Execution Lines

• In-scope: PyVM (semantic reference), LLVM/llvmlite (AOT/EXE harness)
• Out-of-scope: Cranelift JIT and Rust MIR Interpreter (maintenance only during Phase‑15)

MIR14 Policy

• PHI-off at MIR: merges are represented by per-predecessor edge copies
• PHI synthesis is delegated to the LLVM harness (block-head PHIs, typed incoming)
• Verifier runs with verify_allow_no_phi() and edge-copy checks

Parity & Evaluation

• Parity: PyVM vs LLVM output equivalence on curated smokes
• Metrics: runtime, startup time, memory; report only for PyVM/LLVM lines
• Tracing: NYASH_LLVM_TRACE_PHI=1, IR dump NYASH_LLVM_DUMP_IR=...

Toggles

• NYASH_MIR_NO_PHI=1 (default) — PHI disabled at MIR
• Dev-only PHI-on: build with --features phi-legacy and set NYASH_MIR_NO_PHI=0

Notes

• Figures and text must avoid implying MIR-side PHI placement as default.
• Reference canonical specs live under docs/reference/.