JS WAM: opt-in interpreter profiling (UW_PROFILE) - #4207
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Instrument the interpreter behind a single Runtime._prof flag check so the hot path stays allocation-free when profiling is off. UW_PROFILE=1 prints a compact per-predicate table to stderr; UW_PROFILE=json emits a stable JSON object. Lowered dispatch records call counts only. Co-authored-by: johns243a <johns243a@gmail.com>
Co-authored-by: johns243a <johns243a@gmail.com>
PLUnit assertion/1 uses double negation, so Calls/Row never leaked to the subsequent numeric checks. Co-authored-by: johns243a <johns243a@gmail.com>
Runtime.run/collect_run now branch once on Runtime._prof: the off path is the previous instruction loop; instrumentation stays in run_one_instruction. Also cut leftover choice points in the profile table/JSON helpers. Co-authored-by: johns243a <johns243a@gmail.com>
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August 31, 2026 19:58
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Opt-in JS WAM profiler so we can see where a program spends time before investing in indexing depth or parallelism.
Branched from
grok/wamjs-string-literal(extends that stack; net additions only). No shared-file changes; noINTEGRATION_PATCH.md.Activation
Runtime._prof === null). When off,Runtime.run/collect_runuse the same instruction loop as before this change. Remaining cost isif (Runtime._prof)in unify / bind_var / new_var / Call-Execute-Proceed (~0% vs parent on fib(20) wall time; noise).UW_PROFILE=1(alsotrue/yes) → compact table on stderrUW_PROFILE=json→ one JSON object on stderrRuntime.profile(true|"json"|false)andRuntime.profileReport()for programmatic useMetrics
Per-predicate (exclusive):
calls,instr,ns,cps,max_cp_depth,loweredGlobal:
instructions,unify_calls,trail_pushes,heap_cells,backtracks,trail_undos,wall_nsLowered tier: call counts only (dispatch wrapper). Interpreter-tier has instruction/CP/time detail.
JSON schema and table format are documented in
docs/WAM_JAVASCRIPT_STATUS.md.Tests (all green)
tests/test_wam_javascript_builtins.plincluding (a) table + byte-identical stdout, (b) JSON parse withfib/2count ≥ 1, (c) default silent stderr, plus loweredhello/1call countstests/test_wam_javascript_lowered.pltests/test_wam_javascript_fact_sources.plfib(20) sample (
UW_PROFILE=1stderr; stdout byte-identical to unprofiled)(
A2 = +(4181, 2584)is a pre-existing naive-fib register/is-2 display quirk, not introduced here.)