Brummel
76b21c00eb
Deletes `ParamMode::Implicit`. `ParamMode` is now `{Own, Borrow}`:
every fn-type slot on every signature carries an explicit `own` or
`borrow`, no defaulted position survives anywhere (model 0008 §2,
spec 0062). The parser rejects a bare fn-type slot; `borrow-return`
and `borrow-over-value` reject at the signature; the corpus is
migrated to minimal-ownership modes (consumed ⇒ own, read-only-heap
⇒ borrow, value ⇒ trivial-own). The documented `Implicit`-ret-mode
leak is fixed: an owned heap return now drops exactly once (live=0,
acceptance criterion 5).
This was the easy half. Removing the default ACTIVATED a family of
drop paths that `Implicit` had silently skipped — the pre-cutover
language was leaking (and in places mis-dropping) here rather than
crashing, because an Implicit scrutinee turned the drop off. Making
the modes explicit (Own) turned those paths on and exposed two
latent-bug clusters, all fixed RED-first as part of this cutover:
Drop-soundness family (four legs):
A. lit-sub-pattern double-free — the desugar re-matched the same
owned scrutinee in the lit fall-through; fixed by grouping
consecutive same-ctor arms into one match (bind fields once),
in ailang-core desugar.
B. Cons-husk leak on non-tail arm bodies — the lit-sub-pattern
desugar rebound the owned scrutinee via `Let $mp = xs`, which
bumped consume_count and suppressed the existing fn-return
partial_drop. Fixed by not rebinding a bare-Var scrutinee
(one husk-freeing mechanism, not two).
C. polymorphic `drop_<T>` rc_dec'd monomorphised value fields —
the per-ADT drop fn was emitted once from the polymorphic
TypeDef, defaulting type-var fields to ptr and rc_dec'ing
inline Ints (segfault). Fixed with per-monomorph drop
functions (new ailang-codegen::dropmono): the drop set is
collected from the lowered MIR, value-type fields are skipped,
heap fields still freed once; monomorphic-concrete ADTs keep
their byte-identical un-suffixed drop symbol.
D. static Str literal passed to an `(own Str)` param — the
literal lowers to a header-less rodata constant; the callee's
now-active rc_dec read its length field as a refcount and
freed a static address (segfault). Fixed with the missing
fourth StrRep::Static→Heap promotion in lower_to_mir's App arm,
gated on Own mode (borrow args stay static, no regression).
over-strict-mode lint over-fired: it suggested `(borrow V)` for
value-typed params (which `borrow-over-value` rejects — own is the
only legal mode there) and fired on `(intrinsic)` bodies (whose
consumption the linearity walk cannot observe). Tightened to skip
both; contract 0008 updated to the narrowed firing scope.
Irreversible step — canonical-form hash reset (model 0008 §6,
acceptance criterion 6). Every signature now carries explicit modes,
so the hashable canonical JSON changed for every module. RATIFY:
the corpus-wide hash-pin reset (hash_pin, prelude_module_hash_pin,
mono_hash_stability, eq_ord_e2e, embed_export_hash_stable, the
ct4/iter*/loop_recur schema-extension pins) and the list ir_snapshot
golden were regenerated once, deliberately, as the intended one-time
consequence of removing the mode elision from the canonical form —
not a regression. Each regenerated hash verified deterministic across
two runs.
Also fixes a pre-existing latent failure surfaced by the verification
gate, unrelated to this cutover: the `every_contract_names_a_resolvable_
ratifying_test` resolver (design_index_pin) could not resolve the
" + " dual-link ratifying-test form (`uniqueness.rs + linearity.rs`)
that the #57 audit-close (dfdc65f) introduced — it shipped red on that
commit. Resolver taught the dual-link form, mirroring its sibling.
Verification: cargo test --workspace = 731 passed, 0 failed (twice,
stable); e2e 102 passed, no binary exits non-zero (corpus crash-free);
grep-clean for Implicit/fn_implicit/mode_eq across crates; every drop
fix confirmed via emitted IR + AILANG_RC_STATS balance on the head==K,
head!=K, and Nil paths. Three BLOCKEDs en route (the unsound first
husk-dec attempt, the over-strict derivation premise, the leg-B fix
direction) were each treated as a real design/spec gap and rediagnosed,
not patched over.
Supersedes #54 (return-position-only leak patch). Precondition #57
(linearity hardening) was already met. Spec docs/specs/0062, plan
docs/plans/0121.
closes #55
170 lines
5.9 KiB
Plaintext
170 lines
5.9 KiB
Plaintext
; Latency-distribution bench fixture — explicit-mode variant.
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;
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; Companion to bench_latency_implicit. Same algorithm, with
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; `(borrow T)` / `(own T)` annotations so that under --alloc=rc the
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; codegen emits proper inc/dec instrumentation: the persistent tree
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; cache is borrowed (no inc/dec on pin_root's hot path), the per-op
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; IntList is owned by sum_list (param drop at fn return frees the
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; chain). The drop-iterative annotation on IntList keeps the per-op
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; deallocation O(1)-stack regardless of list length.
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;
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; This is the "RC-fair" arm of the latency bench; together with
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; bench_latency_implicit (the implicit-mode control arm at rc) it
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; tests the hypothesis "RC under explicit-mode has p99
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; per-operation latency within a small constant factor of the
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; median, even under continuous alloc pressure with a large
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; persistent live working set".
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;
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; Workload (must match bench_latency_implicit's parameters exactly
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; for the comparison to be fair):
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; - Live cache: balanced binary tree of depth 19 (524_287 nodes,
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; ~16 MB), borrowed throughout the loop.
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; - Per-op: build a CHUNK_LEN-cell IntList of 0..CHUNK_LEN-1, sum
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; it, drop it. CHUNK_LEN, NUM_OPS, PRINT_K hardcoded to match
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; the implicit variant.
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; - Same stdout shape: one READY (8888), N_PRINT timing markers
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; each containing the per-op sum (validatable, always equal),
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; one DONE (9999).
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(module bench_latency_explicit
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(data Tree
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(doc "Balanced binary tree, 32-byte cells. Borrowed across the bench loop; tree-depth recursion at scope close is bounded (depth 19) so no drop-iterative needed.")
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(ctor TLeaf)
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(ctor TNode (con Int) (con Tree) (con Tree)))
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(data IntList
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(doc "Singly-linked Int list. Per-op chains are CHUNK_LEN long; (drop-iterative) keeps Own-param drop O(1) stack regardless of length.")
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(ctor LNil)
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(ctor LCons (con Int) (con IntList))
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(drop-iterative))
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; ---------- Live cache: balanced tree of given depth ----------
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(fn build_tree
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(doc "Build a balanced tree of given depth, every value = 1. Returns owned Tree; main holds it across the loop and the final drop fires at main's scope close.")
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(type
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(fn-type
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(params (own (con Int)))
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(ret (own (con Tree)))))
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(params depth)
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(body
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(if (app eq depth 0)
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(term-ctor Tree TLeaf)
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(term-ctor Tree TNode
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1
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(app build_tree (app - depth 1))
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(app build_tree (app - depth 1))))))
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(fn pin_root
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(doc "Constant-time tree liveness pin — read root tag, return 1 (TNode) or 0 (TLeaf). Borrows t so the persistent cache is not inc/dec'd on every op.")
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(type
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(fn-type
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(params (borrow (con Tree)))
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(ret (own (con Int)))))
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(params t)
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(body
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(match t
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(case (pat-ctor TLeaf) 0)
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(case (pat-ctor TNode v l r) 1))))
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; ---------- Per-op work: build/sum an N-cell list ----------
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(fn cons_n_acc
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(doc "Tail-recursive list builder. Returns owned chain; caller is sum_list which owns and drops it.")
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(type
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(fn-type
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(params (own (con Int)) (own (con IntList)))
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(ret (own (con IntList)))))
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(params n acc)
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(body
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(if (app eq n 0)
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acc
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(tail-app cons_n_acc
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(app - n 1)
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(term-ctor IntList LCons (app - n 1) acc)))))
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(fn cons_n
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(doc "Build [0,1,...,n-1] :: IntList. Returns owned chain.")
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(type
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(fn-type
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(params (own (con Int)))
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(ret (own (con IntList)))))
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(params n)
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(body
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(app cons_n_acc n (term-ctor IntList LNil))))
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(fn sum_list_acc
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(doc "Tail-recursive sum. Owns xs; consumes it via the LCons arm's t binder (move-into-tail-call).")
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(type
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(fn-type
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(params (own (con IntList)) (own (con Int)))
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(ret (own (con Int)))))
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(params xs acc)
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(body
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(match xs
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(case (pat-ctor LNil) acc)
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(case (pat-ctor LCons h t)
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(tail-app sum_list_acc t (app + acc h))))))
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(fn sum_list
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(doc "Sum every element. Owns xs, hands it to sum_list_acc which consumes it.")
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(type
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(fn-type
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(params (own (con IntList)))
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(ret (own (con Int)))))
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(params xs)
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(body
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(app sum_list_acc xs 0)))
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(fn one_op
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(doc "One bench operation: build+sum a fresh CHUNK_LEN-cell list, pin the tree's root, return their sum so the value chain stays observable. Tree is borrowed; no inc/dec on the hot path against the persistent cache.")
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(type
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(fn-type
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(params (own (con Int)) (borrow (con Tree)))
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(ret (own (con Int)))))
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(params chunk_len t)
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(body
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(app + (app sum_list (app cons_n chunk_len)) (app pin_root t))))
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; ---------- Bench loop ----------
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(fn loop
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(doc "Tail-recursive bench loop. Tree is borrowed across all iterations.")
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(type
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(fn-type
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(params (own (con Int)) (own (con Int)) (own (con Int)) (own (con Int)) (borrow (con Tree)))
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(ret (own (con Unit)))
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(effects IO)))
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(params remaining print_countdown chunk_len print_k t)
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(body
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(if (app eq remaining 0)
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(seq (app print 9999) (do io/print_str "\n"))
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(if (app eq print_countdown 0)
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(seq
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(seq (app print (app one_op chunk_len t)) (do io/print_str "\n"))
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(tail-app loop
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(app - remaining 1)
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(app - print_k 1)
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chunk_len
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print_k
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t))
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(let _v (app one_op chunk_len t)
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(tail-app loop
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(app - remaining 1)
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(app - print_countdown 1)
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chunk_len
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print_k
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t))))))
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(fn main
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(doc "Top-level: build tree, signal READY (8888), run loop, signal DONE (9999 emitted by loop).")
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(type (fn-type (params) (ret (own (con Unit))) (effects IO)))
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(params)
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(body
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(let t (app build_tree 19)
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(let _root (app pin_root t)
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(seq
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(seq (app print 8888) (do io/print_str "\n"))
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(app loop 20000 0 500 20 t)))))))
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