Brummel
aee6e9d3bf
Adds a conservative escape analysis that flags Term::Ctor and
Term::Lam allocations as non-escaping when they are bound by a
let, never flow to a fn arg / ctor field / tail-return / lambda
capture, and remain inside the allocating fn's frame. Codegen
lowers flagged sites to LLVM `alloca` instead of `@GC_malloc`;
escaping sites continue to use Boehm.
- escape.rs (new): name-based taint propagation; let-only
candidates; tail-position / app-arg / ctor-field / lam-capture
all taint.
- codegen: three sites switched (lower_ctor, lam env, closure
pair). Save/restore non_escape across lambda thunk emit.
- examples/escape_local_demo.{ailx,ail.json}: focused fixture
exercising both branches (peek and recursive count).
- e2e + escape unit tests: 133 → 141 (+8).
Stop-gate: 17a closes the queue. Memory-management discussion
(GC scope) is the next user-driven step. Per-fn arena observations
appended to JOURNAL — including the headline finding that 0/270
shipped allocations are flagged non-escaping under this rule
(real AILang threads ctors directly between fns; build-locally /
consume-locally is not idiomatic).
All existing fixture stdouts and content hashes bit-identical;
IR snapshots unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
58 lines
2.1 KiB
Plaintext
58 lines
2.1 KiB
Plaintext
; Iter 17a — first fixture exercising the per-fn arena (alloca for
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; non-escaping allocations).
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;
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; `peek` builds a Box(n) and immediately matches on it, returning
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; a literal Int that does not depend on the box's payload. The
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; box's value is fully consumed by the local match — it never
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; flows to a fn arg, never becomes a ctor field, never returns.
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; Iter 17a's escape analysis flags the `(term-ctor Box MkBox n)`
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; allocation as non-escaping; codegen lowers it to LLVM `alloca`
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; instead of `@GC_malloc`. Boehm's heap is not touched at all by
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; this fn.
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;
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; `count` repeats the same pattern under recursion: each call to
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; `count` builds a fresh Box(_), matches it, and returns either 0
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; or 1 + (count rest). Without the alloca optimisation, each
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; recursive frame leaks a Box onto the GC heap until collection;
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; with the optimisation, each frame's Box dies with its frame.
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;
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; Expected stdout (one per line):
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; 42 — peek(0) returns the literal 42 from the only arm
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; 42 — peek(123) ditto (the input value never reaches stdout)
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; 5 — count(5)
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; 0 — count(0)
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(module escape_local_demo
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(data Box (vars a)
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(ctor MkBox a))
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(fn peek
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(doc "Build a Box(n), discard the payload, return 42. The Box is non-escaping.")
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(type (fn-type (params (con Int)) (ret (con Int))))
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(params n)
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(body
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(let b (term-ctor Box MkBox n)
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(match b
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(case (pat-ctor MkBox _) 42)))))
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(fn count
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(doc "Recurse n times; each call builds a temporary Box, discards its payload via _, and returns 0 if n<=0, else 1 + count(n-1).")
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(type (fn-type (params (con Int)) (ret (con Int))))
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(params n)
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(body
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(if (app <= n 0)
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0
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(let b (term-ctor Box MkBox n)
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(match b
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(case (pat-ctor MkBox _) (app + 1 (app count (app - n 1)))))))))
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(fn main
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(type (fn-type (params) (ret (con Unit)) (effects IO)))
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(params)
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(body
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(seq (do io/print_int (app peek 0))
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(seq (do io/print_int (app peek 123))
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(seq (do io/print_int (app count 5))
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(do io/print_int (app count 0))))))))
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