Brummel
f9bf97be80
Per the amended heap-Str ABI spec (2a72a4a), static-Str globals lose
the leading UINT64_MAX sentinel rc-header field that hs.1 introduced.
Layout flips from <{ i64, i64, [N x i8] }> <{ i64 -1, i64 N, ... }>
to <{ i64, [N x i8] }> <{ i64 N, ... }>; the IR-Str pointer now lands
on the len-field at struct-index 0 (was 1) via constexpr-GEP. The four
+8 consumer-side GEPs (@puts / @ail_str_eq / @ail_str_compare / @strcmp)
do not change — the bytes still sit 8 bytes past the len-field. Static-
Str pointers are kept out of ailang_rc_dec at the codegen level via
move-tracking (iter 18d.3) and non-escape lowering (iter 18b), so no
header slot is needed at the global; this is a codegen-level invariant,
not a runtime guard.
Change surface: three format strings + two doc-comments in lib.rs,
rename + assertion update of two IR-shape tests, snapshot regen of
hello.ll. No runtime changes, no checker changes, no new fixtures.
Static-Str globals are now 8 bytes smaller per literal.
cargo test --workspace green; cross_lang.py / compile_check.py /
check.py all green. 3 tasks, 0 re-loops.
82 lines
3.7 KiB
Markdown
82 lines
3.7 KiB
Markdown
# iter hs.2 — Static-Str sentinel-slot retrofit
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**Date:** 2026-05-12
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**Started from:** 51a096cf8354362783d8caf2ec4b35179d935a7a
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**Status:** DONE
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**Tasks completed:** 3 of 3
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## Summary
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Second iter of the heap-Str ABI milestone. Surgical codegen-side
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retrofit of hs.1's static-`Str` global layout: per the amended parent
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spec (`docs/specs/2026-05-12-heap-str-abi.md`) the sentinel rc-header
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slot drops. Language `Str` literals now emit as
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`<{ i64, [N+1 x i8] }> <{ i64 N, [N+1 x i8] c"…\00" }>` instead of
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the hs.1 shape `<{ i64, i64, [N+1 x i8] }> <{ i64 -1, i64 N, …}>`. The
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explicit `len` field becomes the first (and only non-byte) field on
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which the IR-`Str` pointer lands via constexpr-GEP `i32 0, i32 0`. The
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`+8 GEP` consumer-side calls (`@puts`, `@ail_str_eq`, `@ail_str_compare`,
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inline `@strcmp`) do **not** change — the bytes still sit 8 bytes past
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the `len`-field. Static-Str pointers are kept out of `ailang_rc_dec`
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at the codegen level via move-tracking (iter 18d.3) and non-escape
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lowering (iter 18b), so no header slot is needed at the global.
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Change surface: three format-string sites and two doc-comments in
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`crates/ailang-codegen/src/lib.rs`, rename + assertion update of two
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IR-shape tests in the same crate's test module, plus snapshot
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regeneration of `crates/ail/tests/snapshots/hello.ll`. No runtime
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changes, no checker changes, no new fixtures. Static-Str globals are
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now 8 bytes smaller per literal.
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Acceptance verified end-to-end: `cargo test --workspace` green (every
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test result `ok`, 0 failures across the workspace), `bench/cross_lang.py`
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exit 0 (byte-identical stdout across all `ail/c` benchmark pairs),
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`bench/compile_check.py` exit 0, `bench/check.py` exit 0 within the
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known `latency.explicit_at_rc.*` nondeterminism tolerance.
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## Per-task notes
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- iter hs.2.1: renamed `static_str_global_uses_packed_struct_with_sentinel_and_len`
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→ `static_str_global_uses_packed_struct_with_len`; updated its
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doc-comment and assertion substring (struct loses leading `i64, `,
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initialiser loses leading `i64 -1, `). Updated assertion in
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`static_str_callsite_pointer_is_payload_via_constexpr_gep` (name
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preserved — "payload" still describes the `len`-field-as-pointer-target;
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struct loses leading `i64, `, GEP indices `i32 0, i32 1` → `i32 0, i32 0`).
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RED confirmed: both tests fail against hs.1 emission with the expected
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assertion-substring mismatch. The four `+8 GEP` tests stayed green.
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- iter hs.2.2: flipped the global-emission loop format string at
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`lib.rs:471` to the 2-field shape; flipped both `Literal::Str` arms
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(`emit_const_def` ~ `lib.rs:933`, `lower_term` ~ `lib.rs:1255`) to
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emit constexpr-GEP `i32 0, i32 0` onto the 2-field struct type;
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updated the two doc-comments on the `str_literals` field
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(`lib.rs:561`) and on `intern_str_literal` (`lib.rs:2596`) to the
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amended-spec wording. All five edits exactly per plan text. Static_str_
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tests GREEN, `_calls_` tests GREEN, full `cargo test -p ailang-codegen`
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GREEN (33 tests).
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- iter hs.2.3: regenerated `crates/ail/tests/snapshots/hello.ll` via
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`UPDATE_SNAPSHOTS=1 cargo test -p ail --test ir_snapshot hello`. The
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two affected lines (the `@.str_hello_str_0` global and its constexpr-
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GEP at `%v1`) flipped to the new shape; the outer `i64 8` byte offset
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preserved. Workspace `cargo test --workspace` green; `cross_lang.py`,
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`compile_check.py`, `check.py` all green.
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## Concerns
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(none)
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## Known debt
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(none)
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## Files touched
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- `crates/ailang-codegen/src/lib.rs` — three format strings, two
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doc-comments, two test names + assertions + doc-comments
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- `crates/ail/tests/snapshots/hello.ll` — regenerated snapshot
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(2 lines content change, byte offsets preserved)
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## Stats
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bench/orchestrator-stats/2026-05-12-iter-hs.2.json
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