hakorune/docs/reference/jit/jit_stats_json_v1.md

JIT Stats JSON Schema — Version 1

This document describes the fields emitted in the JIT statistics JSON outputs (version=1).

Sources

• Unified JIT stats (VM-side): printed when NYASH_JIT_STATS_JSON=1 (or CLI equivalent)
• Box API: new JitStatsBox().toJson() returns a compact JSON, summary() returns a pretty JSON summary (via VM dispatch)

Version

• version: number — Schema version (currently 1)

Unified JIT Stats (JSON)

• version: number — Schema version (1)
• sites: number — Number of JIT call sites observed
• compiled: number — Count of functions compiled by the JIT
• hits: number — Sum of entries across all functions (hotness hits)
• exec_ok: number — Count of successful JIT executions
• trap: number — Count of JIT executions that trapped and fell back to VM
• fallback_rate: number — Ratio trap / (exec_ok + trap) (0 when denominator is 0)
• handles: number — Current number of live JIT handles in the registry
• abi_mode: string — "i64_bool" or "b1_bool" (when toolchain supports b1)
• abi_b1_enabled: boolean — Whether b1 ABI is requested by config
• abi_b1_supported: boolean — Whether current toolchain supports b1 in signatures
• b1_norm_count: number — Count of b1 normalizations (e.g., i64!=0 to b1)
• ret_bool_hint_count: number — Count of functions lowered with return-bool hint
• phi_total_slots: number — Total PHI slots encountered (always-on, LowerCore-based)
• phi_b1_slots: number — PHI slots classified as boolean (heuristics)
• top5: array of objects — Top hot functions
  • name: string
  • hits: number
  • compiled: boolean
  • handle: number (0 when not compiled)

Compact Box JSON — JitStatsBox.toJson()

• version: number — Schema version (1)
• abi_mode: string — Current ABI mode for booleans (see above)
• abi_b1_enabled: boolean — Whether b1 ABI is requested by config
• abi_b1_supported: boolean — Whether current toolchain supports b1 in signatures
• b1_norm_count: number — b1 normalizations count
• ret_bool_hint_count: number — return-bool hint count
• phi_total_slots: number — Total PHI slots (accumulated)
• phi_b1_slots: number — Boolean PHI slots (accumulated)

Summary Box JSON — JitStatsBox.summary()

• Pretty-printed JSON containing:
  • All fields from toJson()
  • top5: same structure as unified stats

Notes

• Counters reflect process-lifetime totals (reset only on process start).
• phi_* counters are accumulated per LowerCore invocation (function lower), independent of dump flags.
• abi_mode switches to b1_bool when toolchain support is detected and b1 ABI is enabled.

Examples

{
  "version": 1,
  "sites": 1,
  "compiled": 0,
  "hits": 1,
  "exec_ok": 0,
  "trap": 0,
  "fallback_rate": 0.0,
  "handles": 0,
  "abi_mode": "i64_bool",
  "abi_b1_enabled": false,
  "abi_b1_supported": false,
  "b1_norm_count": 0,
  "ret_bool_hint_count": 0,
  "phi_total_slots": 2,
  "phi_b1_slots": 1,
  "top5": [ { "name": "main", "hits": 1, "compiled": false, "handle": 0 } ]
}