dd65cf7e4c
- Unify standard method calls to emit_unified_call; route via RouterPolicy and apply rewrite::{special,known} at a single entry.\n- Stabilize emit-time invariants: LocalSSA finalize + BlockSchedule PHI→Copy→Call ordering; metadata propagation on copies.\n- Known rewrite default ON (userbox only, strict guards) with opt-out flag NYASH_REWRITE_KNOWN_DEFAULT=0.\n- Expand TypeAnnotation whitelist (is_digit_char/is_hex_digit_char/is_alpha_char/Map.has).\n- Docs: unified-method-resolution design note; Quick Reference normalization note; selfhosting/quickstart.\n- Tools: add tools/selfhost_smoke.sh (dev-only).\n- Keep behavior unchanged for Unknown/core/user-instance via BoxCall fallback; all tests green (quick/integration).
60 lines
3.3 KiB
Markdown
60 lines
3.3 KiB
Markdown
# Unified Method Resolution — Design Note (Phase P4)
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Purpose
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- Document the unified pipeline for method resolution and how we will roll it out safely.
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- Make behavior observable (dev-only) and gate any future default changes behind clear criteria.
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Goals
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- Single entry for all method calls via `emit_unified_call`.
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- Behavior-preserving by default: Unknown/core/user‑instance receivers route to BoxCall.
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- Known receivers may be rewritten to function calls (obj.m → Class.m(me,…)) under strict conditions.
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- Keep invariants around SSA and instruction order to prevent sporadic undefined uses.
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Pipeline (concept)
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1) Entry: `emit_unified_call(dst, CallTarget::Method { box_type, method, receiver }, args)`
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2) Special rewrites (early): toString/stringify → str, equals/1 consolidation.
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3) Known/unique rewrite (user boxes only): if class is Known and a unique function exists, rewrite to `Call(Class.m/arity)`.
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4) Routing: `RouterPolicy.choose_route` decides Unified vs BoxCall (Unknown/core/user‑instance → BoxCall; else Unified).
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5) Emit guard: LocalSSA finalize (recv/args in current block) + BlockSchedule order contract (PHI → Copy → Call).
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6) MIR emit: `Call { callee=Method/Extern/Global }` or `BoxCall` as routed.
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Invariants (dev-verified)
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- SSA locality: All operands are materialized within the current basic block before use.
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- Order: PHI group at block head, then materialize Copies, then body (Calls). Verified with `NYASH_BLOCK_SCHEDULE_VERIFY=1`.
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- Rewrites do not change semantics: Known rewrite only when a concrete target exists and is unique for the arity.
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Behavior flags (existing)
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- `NYASH_ROUTER_TRACE=1`: short route decisions to stderr (reason, class, method, arity, certainty).
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- `NYASH_LOCAL_SSA_TRACE=1`: LocalSSA ensure/finalize traces (recv/arg/cond/cmp).
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- `NYASH_BLOCK_SCHEDULE_VERIFY=1`: warn when Copy/Call ordering does not follow the contract.
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- KPI (dev-only):
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- `NYASH_DEBUG_KPI_KNOWN=1` → aggregate Known rate for `resolve.choose`.
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- `NYASH_DEBUG_SAMPLE_EVERY=N` → sample output every N events.
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Flag (P4)
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- `NYASH_REWRITE_KNOWN_DEFAULT` (default ON; set to 0/false/off to disable):
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- Enables Known→function rewrite by default for user boxes if and only if:
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- receiver is Known (origin), and
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- function exists, and
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- candidate is unique for the arity.
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- When disabled, behavior remains conservative; routing still handles BoxCall fallback.
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Rollout note
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- Default is ON with strict guards; set `NYASH_REWRITE_KNOWN_DEFAULT=0` to revert to conservative behavior.
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- Continue to use `NYASH_ROUTER_TRACE=1` and KPI sampling to validate stability during development.
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Key files
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- Entry & routing: `src/mir/builder/builder_calls.rs`, `src/mir/builder/router/policy.rs`
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- Rewrites: `src/mir/builder/rewrite/{special.rs, known.rs}`
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- SSA & order: `src/mir/builder/ssa/local.rs`, `src/mir/builder/schedule/block.rs`, `src/mir/builder/emit_guard/`
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- Observability: `src/mir/builder/observe/resolve.rs`
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Acceptance for P4
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- quick/integration stay green with flags OFF.
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- With flags ON (dev), green remains; KPI reports sensible Known rates without mismatches.
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- No noisy logs in default runs; all diagnostics behind flags.
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Notes
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- This design keeps Unknown/core/user‑instance on BoxCall for stability and parity with legacy behavior.
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- Known rewrite is structurally safe because user box methods are lowered to standalone MIR functions during build.
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