Spec M35 — benchmark tooling (owner, 2026-09-03)

Goal: numbers over time for the compiler and for compiled programs, reproducible and comparable.

• scripts/bench.sh (and make bench): compile-time benchmarks — mc0 src/mc.mc, mc1 src/mc.mc, mc-exe --exe src/mc.mc, examples/* builds — and run-time micro-benchmarks written in mc (bench/*.mc: fib(30), loops with loads/stores, string building, a channel ping-pong from examples/conc, an lx object churn), each run N times with hyperfine when installed else an internal timer; output as a Markdown table and a CSV row (bench/results/<date>-<commit>.csv), plus binary sizes and max RSS (/usr/bin/time -l, vmmap own mappings).
• mc bench subcommand? No — the tool is a script plus mc programs; nothing enters src/.
• CI: a bench job on macos-15 (manual workflow_dispatch and on tags) uploading the CSV as an artifact and appending to a bench branch; the site gets a "Numbers" page rendered from the CSVs.
• Regression guard: make check keeps only the cheap size/RSS ceilings (M34); timings are reported, never asserted (runner noise).

Memory evaluation ("mem paranoid") — owner's addition, 2026-09-03 #

Compiled mc programs cannot use ASan/UBSan (those are clang instrumentation; the seed keeps make stage0-san for the compiler's own C). The equivalent for mc programs is built from the surface, outside the core:

• lib/memcheck.mc (bundled as <memcheck>): a runtime with a shadow map of the program's arena (allocation headers with canaries, red zones, poisoning on free, quarantine for use-after-free, double-free detection, leak report and high-water mark at exit, per-site counters), and a Tier 2 pass() that rewrites every ld8..st64 and &x-derived access into checked calls (mchk_ld64(p, file, line)), plus UBSan-style checks (shift >= 64, division by zero, signed overflow on + - * when asked). Cost is opt-in: nothing changes without the flag.
• Activation: [profile] mem = "paranoid" in mc.toml or mc build --paranoid (and --paranoid on the single-file CLI); the driver builds through a taught compiler that registers the pass and links the runtime; a MC_PARANOID=1 environment switch at run time toggles the report verbosity.
• Taught languages plug in: examples/lang's rc runtime exposes its allocator to the checker so rc_dec below zero, dispose-after-free and leaked objects are reported with the .lx position.
• lib/bench.mc (bundled as <bench>): timers, counters, allocation statistics and a CSV/Markdown reporter for programs, activated by --bench / [profile] bench = true; the M35 tooling uses it.
• Tests: a corpus of deliberately broken programs (tests/mem/*.mc) each expected to be caught with the right message; a clean program with zero reports; overhead measured and documented.
• Distribution to developers: both modules travel in the bundle; mc --paranoid prog.mc works from the binary alone. Nothing enters src/ except the driver flag and the bundle entries.

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