hakorune/docs/development/design/legacy/RESOLVER_API.md

Resolver API (Minimal i64 Prototype)

Goals

• Phase‑15（MIR13運用）における方針: MIR 生成層は PHI を出さず、LLVM 層で PHI を合成する。
• Centralize "ValueId → current-block value" resolution.
• Guarantee dominance by localizing values at the start of the block (before non-PHI).
• De-duplicate per (block, value) to avoid redundant PHIs/casts.

Design

• Resolver-only reads: lowerers must fetch cross-block values via Resolver (ban direct vmap.get for reads across BBs).
• Resolver keeps small per-function caches keyed by (BasicBlockId, ValueId).
• resolve_i64(...) returns an i64-typed value, inserting a PHI at the beginning of the current block and wiring incoming from predecessor end-snapshots (sealed SSA). Any required casts are inserted in predecessor blocks just before their terminators to preserve dominance.
• resolve_ptr(...) returns an i8* value localized to the current block; integer handles are bridged via inttoptr.
• resolve_f64(...) returns an f64 value localized to the current block; ints bridged via sitofp.
• Internally uses sealed snapshots (block_end_values) to avoid referencing values that do not dominate the use.

Usage (planned wiring)

• Create let mut resolver = instructions::Resolver::new(); at function lowering start.
• Replace all integer value fetches in lowerers with resolver.resolve_i64(...).
• Keep builder insertion discipline via BuilderCursor.

Ban: Direct vmap.get(..) for cross-BB reads

• Direct reads from vmap are allowed only for values defined in the same block (after they are created).
• For any value that may come from a predecessor, always go through Resolver.
• CI guard: keep rg "vmap\.get\(" src/backend/llvm at zero for instruction paths (Resolver-only).

Next

• Migrate remaining localize_to_i64 call sites to the resolver.
• Enforce vmap direct access ban in lowerers (Resolver-only for reads).
• ループ（while 形 CFG）の検出と、ヘッダ BB での搬送 PHI 合成（preheader/backedge の 2 incoming）を実装。

Tracing

• NYASH_LLVM_TRACE_PHI=1: log PHI creation/wiring in the Rust/inkwell path.
• NYASH_LLVM_TRACE_FINAL=1: in the Python/llvmlite harness, trace selected final calls (e.g., Main.node_json/3, Main.esc_json/1) to correlate ON/OFF outputs during parity checks.

Acceptance tie-in

• Combined with LoopForm: dispatch-only PHI + resolver-based value access → dominance violations drop to zero (A2.5).