Brummel
1cf281b217
Append three new symbols to runtime/str.c: a private str_alloc(uint64_t)
slab helper that allocates [rc_header | len | bytes... | NUL] via
ailang_rc_alloc and writes the len prefix, plus two extern formatters
ailang_int_to_str(int64_t) and ailang_float_to_str(double) that compose
str_alloc with snprintf("%lld") / snprintf("%g"). Defensive abort() on
truncation; 64-byte stack buffer comfortably oversized for either
formatter.
The extern declaration of ailang_rc_alloc carries __attribute__((weak)).
First regression sweep without it surfaced 11 e2e link failures under
--alloc=gc and --alloc=bump: public T-visible symbols (int_to_str /
float_to_str) pull their transitive callees (rc_alloc) into every
binary's symbol set, but rc.c is not linked under gc/bump in hs.3.
The weak attribute makes the cross-allocator link safe in isolation;
under rc the strong definition wins as usual. Retained after hs.4
(when rc.c becomes unconditionally linked) as a no-op that keeps
str.c link-safe in isolation.
No IR-side caller wired yet — hs.4 lands the IR-header declare lines,
the int_to_str/float_to_str codegen lowering, the checker install,
and the unconditional rc.c link.
cargo test --workspace + cross_lang.py + compile_check.py + check.py
all green on re-sweep.
112 lines
5.4 KiB
Markdown
112 lines
5.4 KiB
Markdown
# iter hs.3 — Heap-Str runtime additions
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**Date:** 2026-05-12
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**Started from:** 187d04814d4485bee1bb85f6f7433c2f3d146fb7
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**Status:** DONE
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**Tasks completed:** 2 of 2
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## Summary
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Third iter of the heap-Str ABI milestone. Single-file additive change
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to `runtime/str.c`: three new symbols (private `static char
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*str_alloc(uint64_t)` slab helper plus two extern formatters
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`ailang_int_to_str(int64_t)` and `ailang_float_to_str(double)`), the
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supporting `<stdint.h>` / `<stdio.h>` / `<stdlib.h>` includes, and an
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`extern void *ailang_rc_alloc(size_t)` declaration. No IR-side caller
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is wired yet — hs.4 will land codegen + checker + linker work that
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makes the formatters live builtins.
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One deviation from the plan: the `extern` declaration of
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`ailang_rc_alloc` was promoted from plain-external to
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`__attribute__((weak))`. The plan's assertion that the new symbols
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sit "present-but-unreferenced" across all `--alloc` strategies turned
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out to be wrong at the link layer — `ailang_int_to_str` /
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`ailang_float_to_str` are publicly-visible `T` symbols, so the linker
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preserves them and their transitive callees (including
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`ailang_rc_alloc`) in every binary regardless of program-level usage.
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Under `--alloc=gc` and `--alloc=bump` the build pipeline does not
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link `rc.c`, so the unresolved-symbol error fires at link time and
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took out 11 e2e tests on the first regression sweep. The weak
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attribute makes the reference link-safe in isolation: under gc/bump
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it resolves to NULL (never dereferenced — no IR caller exists yet);
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under rc the strong definition wins as usual. The attribute is
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retained after hs.4 unconditionally links rc.c (where it becomes a
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no-op) to keep `runtime/str.c` link-safe in isolation, matching the
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spec's "single-file abstraction" framing of the runtime split.
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Acceptance verified: `cargo test --workspace` (zero failures across
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the full test surface), `bench/cross_lang.py` (25/25 metrics stable,
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exit 0), `bench/compile_check.py` (24/24 metrics stable, exit 0),
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`bench/check.py` (zero regressed, exit 0; same five
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`latency.explicit_at_rc.*` improvements outside tolerance that
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audit-cma and audit-ms have already documented as
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not-coupled-to-milestone — baseline left untouched per established
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practice). `clang -c -O2 -Wall -Werror` on `runtime/str.c` standalone
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also exits 0 with no warnings.
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## Per-task notes
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- iter hs.3.1: appended three `#include` lines (`stdint.h`,
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`stdio.h`, `stdlib.h`), one weak `extern void *ailang_rc_alloc`
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declaration, and three new function bodies (`str_alloc`,
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`ailang_int_to_str`, `ailang_float_to_str`) to `runtime/str.c`.
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Compile-check via `clang -c -O2 -Wall -Werror` green; nm
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symbol-table inspection: 4 public `T` symbols (`ail_str_eq`,
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`ail_str_compare`, `ailang_int_to_str`, `ailang_float_to_str`),
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`str_alloc` absent at `-O2` (inlined into both callers — only
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visible as `t str_alloc` at `-O0`; static-linkage invariant
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preserved), `ailang_rc_alloc` shown as `w` (weak undefined).
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- iter hs.3.2: ran the four regression gates. First-pass sweep
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surfaced the 11-test linker failure under `--alloc=gc`/`bump`
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caused by the plan's "rc_alloc reference is harmless if
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unreferenced" assumption; weak-attribute repair re-ran clean. All
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four gates green on the re-sweep.
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## Concerns
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- The plan's Task 1 Step 7 nm-output expected-line block ("`U
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ailang_rc_alloc`" and "`0000000000000000 t str_alloc`") is
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inaccurate at the optimisation level the plan itself specifies
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(`-O2`): the grep regex does not match `ailang_rc_alloc`, and
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`clang -O2` inlines the 2-line `str_alloc` helper into both
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callers so no `t str_alloc` symbol survives the compilation unit.
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Both deviations are `-O2` consequences, not bugs — the
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semantically meaningful invariants (`str_alloc` is static and
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absent from `T`; `ailang_rc_alloc` is a non-`T` undefined
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reference) both hold. A future plan author writing nm-output
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checks should inspect at `-O0` for symbol presence and at `-O2`
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for what actually ships, or relax the expected text from
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literal-match to invariant-check (e.g. "no `T str_alloc`",
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"`ailang_rc_alloc` is `U` or `w`").
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- The plan's core "no build-pipeline change in hs.3" boundary held,
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but the supporting claim "symbols are present in every binary
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regardless of allocator choice" was false at the link layer. The
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weak-attribute repair makes it true at the cost of one extra
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attribute and a long-form doc-comment explaining the cross-
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allocator linking story. A future plan that defers a build-
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pipeline change should explicitly call out cross-translation-unit
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symbol dependencies as a gating concern.
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## Known debt
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- hs.4 will wire `ailang_int_to_str` / `ailang_float_to_str` from
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the IR side and unconditionally link `rc.c`; at that point the
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`__attribute__((weak))` on the `ailang_rc_alloc` declaration
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becomes a no-op (strong definitions always satisfy weak
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references). The attribute is intentionally retained — see the
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doc-comment in `runtime/str.c` — to keep the translation unit
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link-safe in isolation, matching the parent spec's framing of
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`runtime/str.c` as the heap-Str ABI's single point of contact.
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## Files touched
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- `runtime/str.c` — three new functions appended after
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`ail_str_compare`, plus three new `#include` lines and one weak
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`extern` declaration after the existing include block. Existing
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`ail_str_eq` / `ail_str_compare` bodies and the file's top
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comment block untouched.
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## Stats
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bench/orchestrator-stats/2026-05-12-iter-hs.3.json
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