Brummel
14a91f0ae5
Closes Gitea #4. Removes the Boehm-Demers-Weiser conservative GC backend wholesale across six layers in one atomic iteration. After this iter, `AllocStrategy` has two variants (`Rc`, `Bump`), `--alloc=gc` is rejected at CLI parse with `unknown --alloc value`, the libgc link arm is gone, and the design ledger describes RC (canonical) + bump (raw-alloc bench-floor) as the only allocators. Layer-by-layer summary: CLI surface — `crates/ail/src/main.rs`: `parse_alloc_strategy` arm `"gc" => Ok(AllocStrategy::Gc)` removed; error wording updated to `(expected `rc` or `bump`)`; clap-derive `value_parser = ["gc","bump","rc"]` allowlist on BOTH `Build` and `Run` subcommands DROPPED so that `parse_alloc_strategy` remains the sole gatekeeper for the unknown-value diagnostic (otherwise clap shadows the runtime diagnostic with `invalid value 'gc' for '--alloc'`, which would miss the milestone-pin's stderr substring check). The `default_value = "rc"` stays. Codegen — `crates/ailang-codegen/src/lib.rs`: `AllocStrategy::Gc` variant + `Default` derive removed (no caller of `AllocStrategy::default()` existed in the workspace, so the trait derivation was dead). `fn_name` (spec called it `runtime_alloc_fn` loosely; actual identifier is `fn_name`) drops the `Gc => "GC_malloc"` arm. `lower_workspace` and `lower_workspace_staticlib` defaults flip from `Gc` to `Rc`. In-source negative-complement codegen test (mod tests, lib.rs:3571ff) retargets from `AllocStrategy::Gc` to `AllocStrategy::Bump` (bump also doesn't emit per-type drop fns; the test's semantic "no drop fns under non-RC" is preserved). Link branch — `crates/ail/src/main.rs:2389ff`: The `match strategy { AllocStrategy::Gc => { ... cmd.arg("-lgc"); ... } }` arm and its libgc-link block are entirely gone. The surviving match exhausts on `Bump` and `Rc` (Rust's exhaustiveness check confirms; no `error[E0004]`). Staticlib-guard diagnostic rewritten to drop the "shared Boehm collector" phrasing while preserving the prefix `staticlib (swarm) artefact is RC-only` verbatim (the surviving `staticlib_bump_is_rejected` test depends on that substring). Test suite — 3 pure-differential e2e tests deleted (`gc_handles_recursive_list_construction`, `alloc_rc_produces_same_stdout_as_gc`, `alloc_rc_matches_gc_on_std_list_demo`); 9 RC-feature tests stripped of their `stdout_gc` build call and differential `assert_eq!(stdout_gc, stdout_rc, ...)` (absolute `assert_eq!(stdout_rc.trim(), "<n>")` pin retained as correctness oracle); `staticlib_gc_is_rejected` deleted; new milestone-pin `crates/ail/tests/boehm_retirement_pin.rs` asserts `ail build --alloc=gc` exits ≠ 0 with stderr containing `unknown --alloc value` and `\`gc\``; `examples/gc_stress.ail` fixture deleted (no remaining references). Implementer expansion (not in plan): `iter17a_local_box_alloca` (in `e2e.rs`) carried an IR-shape assertion against `@GC_malloc`-absence as the witness for non-escaping allocation. After the Task-2 codegen default flip, the witness shifts to `@ailang_rc_alloc`-absence in escape-targeted positions; assertion + doc-comment updated. Property protected ("no heap allocation in non-escaping contexts") is unchanged; only the named allocator shifts. Bench harness — `bench/run.sh` 9→6 column compaction (workload + bump(s) + rc(s) + rc/bump + bump RSS + rc RSS); gc-arm `bench_latency_implicit_gc` build call + harness invocation dropped from latency block; header comment reframed from "GC-overhead bench harness" to "RC-overhead bench harness"; "Decision 10's Boehm-retirement target (1.3x)" rewording to "RC-overhead-vs-bump bench-health regression gate". `bench/check.py:62` header-sentinel changes from `"gc(s)" in line` to `"bump(s)" in line`; column-count check at `:72` flips from `!= 9` to `!= 6`; per-workload field set drops `gc_s`/`gc_over_bump`/`gc_rss_kb`; `ARM_LABEL_TO_KEY` drops the `"implicit @ gc": "implicit_at_gc"` entry. `bench/baseline.json` regenerated via `--update-baseline`. Implementer note (planner-defect): `write_new_baseline` iterated over the *existing* baseline's metric list when emitting the regenerated file, so even after parser-level `gc_*` removal, the fallback emitted them back into the JSON. Scrubbed post-update; the cleaner fix (have `write_new_baseline` emit only keys present in `parsed_throughput[workload]`) is a follow-up if the script becomes load-bearing for further allocator changes. Design ledger — `design/models/rc-uniqueness.md` excises the `## Dual allocator — RC canonical, Boehm parity oracle` section and the `Boehm-Demers-Weiser conservative GC` choice block + rationale + trade-offs; the per-fn-alloca section generalises Boehm-specific language to allocator-agnostic; the memory-model section's `## Choice.` paragraph reframes the 1.3× target from "Boehm-retirement gate" to "bench-health regression gate". `design/models/pipeline.md` drops the `--alloc=gc → links libgc` arm of the pipeline diagram and replaces it with `--alloc=bump → links bump-floor`; the accompanying prose rewrites accordingly. `design/contracts/scope-boundaries.md` rewrites the "Memory management via Boehm conservative GC" bullet to describe RC + per-fn-arena present-tense; the dead reference to `examples/gc_stress.ail.json` (file never existed; the fixture only ever had a `.ail` form, deleted by this iter) is dropped along with the `examples/std_list_stress.ail.json` reference whose purpose was Boehm-only soak testing. `:67`'s `@printf` / `@GC_malloc` parenthetical updated. `design/contracts/memory-model.md:232` drops the "leaks like the pre-Boehm era" phrase; the RC inc/dec instrumentation is wired up, so the "until then" conditional that referenced pre-Boehm is closed. `design/contracts/embedding-abi.md:42-44` rewrites the staticlib-guard prose to drop the `--alloc=gc` clause (gc is now a CLI-parser-level unknown-value, not a staticlib-guard rejection) and reframe the swarm-safety justification around `--alloc=bump` (leak-only bench instrument) rather than the historical Boehm collector. Honesty pin — `crates/ailang-core/tests/docs_honesty_pin.rs` inverts the polarity: the present-tense Boehm-anchor assertion on `pipeline.md` (`:116-117`) is deleted, and four absence-pins are added to `design_md_has_no_wunschdenken` against the Boehm-zombie strings `transitional Boehm`, `parity oracle`, `GC_malloc`, `libgc`. The `design_corpus()` already includes `rc-uniqueness.md` so no path-list change was needed for the new pins to scan. `crates/ailang-core/tests/design_index_pin.rs:166` drops the `"pre-Boehm"` token from the protected-exception comment list (the phrase no longer appears in `memory-model.md` after this iter, so the exception is dead). Runtime docs — `runtime/bump.c`, `runtime/rc.c`, `runtime/str.c` header comments scrubbed of Boehm/`GC_malloc`/`libgc` references. `bump.c`'s function signature description still documents `void *bump_malloc(size_t)` as the bench-floor allocator interface, but no longer cross-references libgc. Example fixtures — `examples/bench_latency_implicit.ail`, `bench_latency_explicit.ail`, `escape_local_demo.ail`, `reuse_as_demo.ail`, `rc_pin_recurse_implicit.ail` doc-comment headers scrubbed of `--alloc=gc` / Boehm references. The `.ail` surface (AST) is untouched in every case; round-trip invariant holds (`cargo test -p ailang-surface --test round_trip` green). Skill / agent prompts — `skills/audit/agents/ailang-bencher.md` rewritten to use an RC-vs-bump worked example pattern for the hypothesis-driven bench tutorial, replacing the recurring "RC vs Boehm under heap pressure" example. `skills/implement/agents/ailang-implementer.md` Decision-10 / Boehm references replaced with present-tense RC-commitment framing. IR snapshots — the 5 checked-in snapshots (`crates/ail/tests/snapshots/{hello,list,max3,sum,ws_main}.ll`) regenerated via `UPDATE_SNAPSHOTS=1 cargo test -p ail --test ir_snapshot`. Each previously contained `declare ptr @GC_malloc(i64)` and (for `list.ll`) a `call ptr @GC_malloc(...)` invocation; post-flip the snapshots contain `declare ptr @ailang_rc_alloc(i64)` plus the rc inc/dec runtime declarations. Spec-vs-acceptance addendum (caught at orchestrator end-report, absorbed here rather than in a follow-up spec edit): spec §6 acceptance criteria said "Boehm-grep returns matches ONLY in docs_honesty_pin.rs". The plan itself prescribed historical Boehm references in 3 additional files: (a) the new milestone-pin `boehm_retirement_pin.rs` (must literally invoke `--alloc=gc` to assert its rejection), (b) `embed_staticlib_alloc_guard.rs` file doc-comment historical note ("`--alloc=gc` no longer exists as a CLI value"), (c) `embedding-abi.md:44-45` contract historical clause ("see the Boehm-retirement iter"). All three are prescribed; the spec's grep wording was too narrow. The four absence-pins in `docs_honesty_pin.rs` catch the actual zombies (Boehm-narrative re-emerging in the design ledger), which is the substantive intent the spec was aiming at — the four extra documented-by-design exceptions are the cost of having an explicit milestone-pin and contract-level historical anchors. Net delta: - 32 files modified, 2 new (boehm_retirement_pin.rs + stats), 1 deleted (gc_stress.ail); - workspace tests: every binary `0 failed`. Pass-count delta: -3 net (4 e2e tests deleted, 1 new milestone-pin test added); - boehm-grep state: hits only in the four by-design exceptions documented above; - `bench/check.py` exit 0 against regenerated baseline; - CLI must-fail fixture: `ail build --alloc=gc examples/hello.ail` exits non-zero with stderr containing `unknown --alloc value` and `\`gc\``; - design ledger present-tense honest (Boehm-narrative gone from `rc-uniqueness.md` + `pipeline.md`; the few historical references in `embedding-abi.md` / `boehm_retirement_pin.rs` / `embed_staticlib_alloc_guard.rs` are explicit milestone-pins or contract anchors, not silent ledger residue). Bench measurement variance noted: closure-chain and hof-pipeline are ±1-5% jittery between runs; one regeneration flagged 2 metrics as `regressed` before a second run returned 0. The captured baseline is within self-comparison range. Existing per-metric tolerances absorb the jitter. Stats file: `bench/orchestrator-stats/2026-05-20-iter-boehm-retirement.1.json`. closes #4
3.4 KiB
Embedding ABI
Embedding ABI
ail build --emit=staticlib compiles a module to a relocatable
lib<entry>.a (program objects only) plus a separate
libailang_rt.a (the RC runtime: rc.c + str.c), with no
@main trampoline and no MissingEntryMain requirement — a
kernel module is a library.
Each fn carrying (export "<sym>") (schema: FnDef.export) is
emitted as an externally-visible C entrypoint @<sym> forwarding to
the internal @ail_<module>_<fn>. The symbol is author-chosen and
decoupled from the ail_<module>_<def> mangling so a module/fn
rename does not move the C symbol.
The set that can cross the boundary is exactly: Int (lowered
i64), Float (lowered double), or a single-constructor record
whose every field is one of those (crossing as a bare ptr to the
box layout below); the fn's effect set must be empty. There is no
general value-marshalling layer — the host hand-constructs and
hand-reads that box layout directly, so the enumerated set is the
whole contract, narrow by construction, not a subset of a wider
embedding ABI. Because the box layout is the host's contract
surface with no accessor indirection, it is a one-way commitment
frozen as of M3: a compiler change MUST NOT move the box offsets
below for an exported type, nor invert the host-free rule.
These are enforced at ail check (export-non-scalar-signature,
export-has-effects) — an effectful or non-scalar export fails to
typecheck. Every exported entrypoint takes a mandatory leading ailang_ctx_t*
(M2): a per-thread embedding context created by ailang_ctx_new()
and released by ailang_ctx_free(), owned by the calling thread for
its lifetime. The host links one ailang_ctx_t per OS worker thread
and the runtime accounts RC alloc/free into it: the per-allocation
hot path (the per-ctx counters and the per-object refcount header)
is non-atomic by design and never shared — a box never crosses a
thread (Ctx: !Send) and each ailang_ctx_t is
single-thread-per-ctx. The one datum a multi-threaded host shares
is the global RC-stats fallback counter (used when no ctx is
bound); it is atomic-relaxed so the swarm's leak accounting is
exact. The swarm artefact is data-race-free, sanitiser-verified.
The staticlib swarm artefact is RC-only:
ail build --emit=staticlib rejects --alloc=bump (the bench
stub is leak-only and not swarm-safe; --alloc=gc no longer
exists as a CLI value — see the Boehm-retirement iter). The
value/record
layout is frozen as of M3 (see Frozen value layout); the
ctx-threaded C signature is the M2 shape.
Export parameters are written bare: a scalar type carries no
own/borrow mode (a single-constructor record export parameter,
by contrast, carries own/borrow — see memory model
for the full ownership contract; the
frozen value layout below specifies how that contract lands at the C ABI). The
canonical M1 export shape:
(fn step
(export "backtest_step")
(type
(fn-type
(params (con Int) (con Int))
(ret (con Int))))
(params state sample)
(body
(app + state (app * sample sample))))
ail emit-ir <module> --emit=staticlib prints this kernel's LLVM
IR (the external @<sym> forwarders, no @main) instead of the
executable-path main-required rejection — the Decision-5
IR-readability affordance for a main-free kernel.
Ratified by: crates/ailang-codegen/tests/embed_record_layout_pin.rs.