Brummel
4ec8f90b19
Third tranche, completing the honesty-rule sweep across the remaining
contracts. Same conservative bar: cut unbacked-verification claims,
change/deletion history, and forward-intent; keep present-state design
rationale.
- 0003: drop "sanitiser-verified" — no TSan/sanitiser test exists in
the tree, so the claim asserts a verification that does not happen.
The data-race-freedom property (argued from the non-atomic-but-never-
shared hot path + atomic-relaxed shared counter) stays.
- 0008: the `Type::Con.name` hash paragraph ("the tightening shifted
the hashes ... The new pins ... re-asserts the pre-tightening hashes")
-> present-state: which fixtures carry which hash shape and which test
pins each.
- 0013: drop "the former codegen-side fallback (at ..., and the
now-deleted `synth_with_extras`) is retracted" (deletion history; the
present fact is that codegen does not re-resolve, per the boundary);
"A future refactor that loosens any one of the four breaks ..." ->
present-tense statement that the four are load-bearing and each pinned.
- 0017: drop "a real cost surfaced by the `bench_closure_chain`
regression at the operator-routing-eq-ord milestone" (history) and
"the symmetric extensions are mechanical when the first such workload
appears" (forward-intent); keep the present-state allocation cost, the
pin, and the Int-only-asymmetry rationale.
All 18 contracts now reviewed against the code. Ledger pins green;
honesty sweep clean.
75 lines
3.4 KiB
Markdown
75 lines
3.4 KiB
Markdown
# Embedding ABI
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## Embedding ABI
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`ail build --emit=staticlib` compiles a module to a relocatable
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`lib<entry>.a` (program objects only) plus a separate
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`libailang_rt.a` (the RC runtime: `rc.c` + `str.c`), with **no**
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`@main` trampoline and **no** `MissingEntryMain` requirement — a
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kernel module is a library.
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Each `fn` carrying `(export "<sym>")` (schema: `FnDef.export`) is
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emitted as an externally-visible C entrypoint `@<sym>` forwarding to
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the internal `@ail_<module>_<fn>`. The symbol is author-chosen and
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decoupled from the `ail_<module>_<def>` mangling so a module/fn
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rename does not move the C symbol.
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The set that can cross the boundary is exactly: `Int` (lowered
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`i64`), `Float` (lowered `double`), or a single-constructor record
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whose every field is one of those (crossing as a bare `ptr` to the
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box layout below); the fn's effect set must be empty. There is no
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general value-marshalling layer — the host hand-constructs and
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hand-reads that box layout directly, so the enumerated set *is* the
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whole contract, narrow by construction, not a subset of a wider
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embedding ABI. Because the box layout is the host's contract
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surface with no accessor indirection, it is a **one-way commitment
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frozen as of M3**: a compiler change MUST NOT move the box offsets
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below for an exported type, nor invert the host-free rule.
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These are enforced at `ail check` (`export-non-scalar-signature`,
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`export-has-effects`) — an effectful or non-scalar export *fails to
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typecheck*. Every exported entrypoint takes a mandatory leading `ailang_ctx_t*`
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(M2): a per-thread embedding context created by `ailang_ctx_new()`
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and released by `ailang_ctx_free()`, owned by the calling thread for
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its lifetime. The host links one `ailang_ctx_t` per OS worker thread
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and the runtime accounts RC alloc/free into it: the per-allocation
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hot path (the per-ctx counters and the per-object refcount header)
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is non-atomic by design and never shared — a box never crosses a
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thread (`Ctx: !Send`) and each `ailang_ctx_t` is
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single-thread-per-ctx. The one datum a multi-threaded host shares
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is the global RC-stats fallback counter (used when no ctx is
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bound); it is atomic-relaxed so the swarm's leak accounting is
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exact. The swarm artefact is data-race-free by this split.
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The staticlib swarm artefact is **RC-only**:
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`ail build --emit=staticlib` rejects `--alloc=bump` (the bench
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stub is leak-only and not swarm-safe; `--alloc=gc` no longer
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exists as a CLI value — see the Boehm-retirement iter). The
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value/record
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layout is **frozen as of M3** (see [Frozen value layout](0006-frozen-value-layout.md)); the
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ctx-threaded C signature is the M2 shape.
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Export parameters are written **bare**: a scalar type carries no
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`own`/`borrow` mode (a single-constructor record export parameter,
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by contrast, carries `own`/`borrow` — see [memory model](0008-memory-model.md)
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for the full ownership contract; the
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frozen value layout below specifies how that contract lands at the C ABI). The
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canonical M1 export shape:
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```
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(fn step
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(export "backtest_step")
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(type
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(fn-type
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(params (con Int) (con Int))
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(ret (con Int))))
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(params state sample)
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(body
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(app + state (app * sample sample))))
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```
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`ail emit-ir <module> --emit=staticlib` prints this kernel's LLVM
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IR (the external `@<sym>` forwarders, no `@main`) instead of the
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executable-path `main`-required rejection — the Decision-5
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IR-readability affordance for a `main`-free kernel.
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Ratified by: `crates/ailang-codegen/tests/embed_record_layout_pin.rs`.
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