226 lines
16 KiB
Markdown
226 lines
16 KiB
Markdown
# C/C++ kernel port (R7a) — the bug-for-bug checklist
|
||
|
||
**Status: COMPLETE — walker SHIPPED + gates PASSED, c/cpp DEFAULT-ROUTED
|
||
(2026-07-17).** Walker: `codegraph-kernel/src/ccpp/mod.rs` (one dual-language
|
||
module, every branch below mirrored; its header comment lists the quirks).
|
||
Grammars: tree-sitter-c v0.24.2 (`b780e47`, parser.c `f2883ff9…`) +
|
||
tree-sitter-cpp v0.23.4 (`f41e1a0`, parser.c `2a35a43b…`, scanner.c
|
||
`cf60387d…`), crates pinned `=exact` in Cargo.toml, wasm vendored from the
|
||
same tags, kernel-grammar-parity green. preParse HOISTED to the route point
|
||
(`preParsedSource` in src/extraction/kernel/index.ts — both tryKernelExtract
|
||
and the raw bulk path), so no blanking ported to Rust.
|
||
|
||
**Gate results (2026-07-17):**
|
||
- Parity sweeps — **0 diffs on every compared file**: redis 592, git 790,
|
||
fmt 42, protobuf 925, ALS-Community (UE spot-check) 40 files byte-parity.
|
||
- Full-init dump-diffs — **byte-identical** kernel-arm vs wasm-arm: redis
|
||
(131,921 dump lines), git (160,844), fmt (35,433), protobuf (780,620),
|
||
ALS (3,694).
|
||
- Torture fixtures torture.c/.cpp/.hpp + CRLF variants + Metal/CUDA
|
||
hoist-parity + defer tests in `__tests__/kernel-ccpp-parity.test.ts`; new
|
||
preParse blanks unit-tested in extraction.test.ts; full suite green with
|
||
`CODEGRAPH_KERNEL_EXPECT=1`.
|
||
- **Deferral-rate guard — CORRECTED BY MEASUREMENT** (the §4f pattern): the
|
||
<10% bar was calibrated on ts/java/py/go (0–0.42% parse-error incidence).
|
||
Macro-heavy C/C++ genuinely parses with errors at double-digit file rates
|
||
(final sweeps: als 9%, git 16.1%, redis 25.3%, protobuf 25.8%, fmt 42% —
|
||
fmt's template metaprogramming + `.operator[]`-in-decltype shapes are
|
||
grammar-inherent), and every erroring file defers BY POLICY. Measured with
|
||
the defer disabled (`CODEGRAPH_KERNEL_CCPP_ERROR_EXTRACT=1`, sweep-only
|
||
hatch): recovery-divergence is real (21/207 redis, 8/382 git, 9/31 fmt
|
||
erroring files extract differently across UTF-8/UTF-16), so the defer
|
||
stays. The sweep harness now takes `--max-deferral` (default 0.1; use 0.5
|
||
for c/cpp — a broken walker still trips it by deferring ~everything).
|
||
- **Seven NEW/extended preParse blanks** cut real incidence (from 32%/52%
|
||
starting points; linux `kernel/`+`mm/` subtrees 79% → 58%), each
|
||
offset-preserving, TS-side, shared by both arms, and a graph-quality win
|
||
for the wasm path itself (git 7.1k → 13.3k nodes; the linux subtrees
|
||
2.4k → 7.2k — NOTE these are parity-sweep compared-file totals, NOT
|
||
full-graph counts: round 2 established that full-graph node deltas are
|
||
small because wasm error recovery was already salvaging most SYMBOLS on
|
||
deferred files; the blanks' full-graph win is EDGES + phantom cleanup —
|
||
see the round-2 record below): `#ifdef __cplusplus` guard bodies, lone macro lines
|
||
(`FMT_BEGIN_NAMESPACE`, `Q_OBJECT`), C statement iterator macros
|
||
(`list_for_each_entry(…) { }` and brace-less bodies), C trailing param
|
||
attrs (`int argc UNUSED`), the curated Linux/sparse annotation list
|
||
(`__init`/`__user`/… — structural matching is impossible there: `__u32
|
||
count` is shape-identical; parameterized `__printf(1,2)` guarded out) +
|
||
`container_of`'s type-keyword argument, leading attr macros extended to
|
||
cpp, and directive-line restore (stops the older blanks corrupting
|
||
`#define` lines).
|
||
- **Defer-reuse (the linux-economics fix):** a deferred file used to pay the
|
||
pipeline three times — the worker's raw kernel try, extractFromSource's
|
||
kernel RE-try, then wasm with a third preParse. A one-slot defer memo in
|
||
the route point short-circuits the repeat kernel attempt and hands the
|
||
already-blanked source to the wasm fallback (`sourceIsPreParsed`). On
|
||
linux this + the annotation blanks took the kernel-arm parse-loop from
|
||
560s (WORSE than the 426s wasm arm) to **356s vs 435s wasm-arm (−18%)**,
|
||
and the 2c/6GB envelope to **19.1 min kernel-arm vs 22.9 min wasm-arm
|
||
(−17%)** with a RICHER graph (2,048,295 nodes / 6,406,933 edges; two
|
||
independent kernel-arm runs byte-same counts).
|
||
- **Linux-scale dump gate:** kernel-arm and wasm-arm full graphs are
|
||
**byte-identical** — `dump-graph.mjs` over both 5.2GB DBs:
|
||
10,444,551 dump lines each, sha256 `cd4182e6…` on both. (Dumping a 2M-node
|
||
DB needs a big-heap host run — `node --max-old-space-size=16000 …
|
||
> file` then hash the FILE; the in-container 6GB heap OOMs and a straight
|
||
pipe at GB scale dies with ENOBUFS, both of which silently hash truncated
|
||
output as the empty stream.)
|
||
|
||
- **Deferral round 2 (2026-07-18)** — eight new C-only passes + word-list
|
||
extensions took the linux `kernel/`+`mm/` deferral **58.6% → 33.9%**
|
||
(483 → 279 of 824 files; census-driven: `bucket-defers.mjs` clusters each
|
||
deferring file's FIRST post-preParse error-line shape). New passes, all in
|
||
`preParseCSource`: parameterized-annotation whole-blank (`__free(kfree)`,
|
||
`__printf(4,0)`, `__counted_by(n)`, `__bpf_md_ptr(…)` — extends through a
|
||
stranded field `;`, since a lone-`;` field errors but an empty struct body
|
||
doesn't), type-keyword-arg scanner (`kzalloc_obj(struct T)`,
|
||
`list_entry(p, struct T, m)` — a bounded hand scanner, NOT a nested regex
|
||
(backtracking risk on untrusted repos); head exclusions
|
||
sizeof/offsetof/`_Generic`/va_arg + call-vs-declaration guard: an
|
||
identifier or `*` before the head rejects, `return` excepted; blanks
|
||
trailing stars so `DEFINE_PER_CPU(struct T *, x)` leaves two plain
|
||
idents), `static|extern CAPS_MACRO(…);` whole-line blank at ANY scope
|
||
(bare `EXPORT_SYMBOL(x);` parses natively as a K&R decl — probed — and
|
||
stays), the ONE REWRITE in the family — `static CAPS(type, name) = {` →
|
||
`static <type> <name> = {` (name + tail keep exact offsets via d-flag
|
||
indices; blanking would strand the brace block or discard initializer
|
||
fn-refs), `va_arg(ap, const char *)` second-arg blank (single-token
|
||
`va_arg(ap, int)` parses natively — probed), GNU named-variadic
|
||
`#define f(args...)` DOTS-only blank (post-`restoreDirectiveLines` by
|
||
design; whole-tail blanking fails — `#define NAME` + trailing spaces
|
||
errors, measured), storage-sandwiched lowercase markers
|
||
(`static notrace void` — the sandwich is the guard), C23 `auto`
|
||
(`auto x =` only; `auto int x` untouched), and multi-line spans for the
|
||
statement-iterator-macro blank (`hlist_for_each_entry_rcu(…,\n
|
||
lockdep_is_held(&m)) {` — bails on `;`/braces mid-span). Word list +=
|
||
cacheline family (2- AND 4-underscore spellings), `__noclone`,
|
||
`__lockfunc`, `__ref`, `__private`, `__bitwise`, `__nosavedata`,
|
||
`__no_kcsan`, `__cpuidle`, `__ksym`, `__net_initdata`,
|
||
`__initdata_memblock`/`_or_meminfo`. Cross-repo: git 16.1 → 12.2%,
|
||
redis 25.3 → 24.1%, fmt/protobuf unchanged (cpp-dominant — C-only passes,
|
||
correct), **0 diffs all five sweeps**. Linux full-tree (2c gate runs):
|
||
kernel-arm parse **356 → 306s**, envelope 19.1 → ~17.1min (host-
|
||
contaminated, indicative), counts **2,049,153 / 6,413,518** (+858 nodes,
|
||
**+6,585 edges** vs R7a — the SYMBOLS were mostly already error-recovered;
|
||
the graph win is relationships + phantom cleanup). Deliberately skipped:
|
||
`#ifdef CONFIG_X` if/else interleaves + labels (genuine preprocessing),
|
||
TP_PROTO/TRACE_EVENT DSL headers (no real code to recover), `module_init(x)`
|
||
without `;` (K&R-definition ambiguity), single-token va_arg (native).
|
||
Torture fixture grew a round-2 section (both-arm parity pinned); unit
|
||
tests in extraction.test.ts; suite 2517 green.
|
||
|
||
The sections below are §0a-recipe step 1's output — every TS-side branch the
|
||
walker mirrors, with file:line anchors (as of `705e501`). Read WITH
|
||
`docs/design/rust-kernel-migration-plan.md` (§0a recipe, §5 gates).
|
||
|
||
## Architecture decisions (already made by the plan)
|
||
|
||
1. **preParse stays TS-side and is HOISTED to the route point.**
|
||
`tryKernelExtract(filePath, source, lang)` currently receives RAW source
|
||
(`tree-sitter.ts:6707`); the wasm path applies `extractor.preParse` inside
|
||
`TreeSitterExtractor` (`tree-sitter.ts:488`). For kernel-routed c/cpp, apply
|
||
the SAME preParse before the kernel call so both arms parse identical
|
||
blanked bytes — all seven blanking passes (`preParseCppSource` /
|
||
`preParseCSource`, `languages/c-cpp.ts:698/750`) then need NO Rust port,
|
||
and every offset survives (they're all equal-length-space replacements).
|
||
2. **Metal + CUDA ride the cpp route** (corrected from the first draft):
|
||
`.metal`/`.cu` map to language `'cpp'` at detectLanguage (grammars.ts:135),
|
||
so there is no separate routing decision — when cpp routes to the kernel,
|
||
those files come along as blanked cpp. The preParse hoist MUST pass
|
||
`filePath` (the extension gates Metal-attribute blanking) and the CUDA
|
||
content gate rides for free. Their suite tests are the parity insurance.
|
||
3. **One walker module, dual language** (`codegraph-kernel/src/ccpp/`), flagged
|
||
c vs cpp like `tsjs/` flags its four dialects. Grammars: tree-sitter-c +
|
||
tree-sitter-cpp crates, wasm vendored from the SAME tags (sha-matched
|
||
parser.c + scanner, ts-cli 0.25.10). Upgrade the production wasm FIRST and
|
||
get the full suite green before the walker exists (isolate grammar-bump
|
||
effects, as R2 did for TS/JS).
|
||
|
||
## Extractor configs (languages/c-cpp.ts — read the whole file when porting)
|
||
|
||
**cExtractor (line 180):** functionTypes=[function_definition]; NO
|
||
class/method/interface types; structTypes=[struct_specifier];
|
||
unionTypes=[union_specifier] (a named `union U { … };` is a definition, and
|
||
`typedef union { … } N;` resolves to a first-class `union` node);
|
||
enumTypes=[enum_specifier]; enumMemberTypes=[enumerator];
|
||
typeAliasTypes=[type_definition]; importTypes=[preproc_include];
|
||
callTypes=[call_expression]; variableTypes=[declaration];
|
||
nameField=declarator; isConst = any child `type_qualifier` with text
|
||
`const`; getReturnType = extractCppReturnType; resolveTypeAliasKind =
|
||
typedef enum/struct with body → that kind (anon inner specifier takes the
|
||
typedef's name); extractImport: `system_lib_string` → strip `<>`, else
|
||
`string_literal>string_content`; signature = full `#include` line.
|
||
recoverMangledName = recoverMangledCppName (post-parse salvage, PORT).
|
||
|
||
**cppExtractor (line 755):** adds classTypes=[class_specifier] with
|
||
**skipBodilessClass** (forward decls / elaborated refs mint no node, #1093);
|
||
methodTypes=[function_definition] (method vs function decided by
|
||
isInsideClassLikeNode); typeAliasTypes += alias_declaration (`using X = …`);
|
||
resolveName = extractCppQualifiedMethodName (line 75: macro-recovered name
|
||
first, else LAST `::` segment of the declarator's qualified_identifier —
|
||
found by BFS that SKIPS parameter_list + trailing_return_type, line 13);
|
||
getReceiverType = extractCppReceiverType (line 86: the qualifier prefix,
|
||
`stripCppTemplateArgs`-normalized — multi-line template args must not leak
|
||
newlines into qualifiedName, #1286/NAME_MAX); getReturnType =
|
||
extractCppReturnType → normalizeCppReturnType (line 122: smart-ptr/optional
|
||
unwrap to pointee, cv/template/ptr strip, last `::` segment, primitives →
|
||
none — set CPP_NON_CLASS_RETURN line 108); getVisibility = nearest preceding
|
||
`access_specifier` scan in the parent's children (line 785);
|
||
isMisparsedFunction (line 811): name starts `namespace`, name ∈
|
||
{switch,if,for,while,do,case,return}, or isMacroMisparsedTypeDecl (line 261:
|
||
bodyless class/struct specifier in `type` + non-function_declarator
|
||
declarator → DROP the node).
|
||
|
||
**Name-salvage helpers to port exactly:** recoverCppMacroDefinedName (line
|
||
49 — ALL-CAPS-with-underscore parsed name + first param a LONE lowercase
|
||
type_identifier + ≥2 params + NO other lone-identifier param; gtest
|
||
`TEST_F(Fixture, Name)` / `PYBIND11_MODULE(ext, m)` bail);
|
||
recoverMangledCppName (line 406 — only already-mangled names, `Ret (name)`
|
||
idiom left alone, last token before `(`, primitive/keyword guard);
|
||
stripCppTemplateArgs (line 157 — depth-counted removal of every balanced
|
||
`<…>`); cDeclaratorIdentifier (tree-sitter.ts:234 — declarator chain walk,
|
||
function_declarator → null, 12-hop guard).
|
||
|
||
## tree-sitter.ts branches (anchors as of `705e501`)
|
||
|
||
| Line | Mechanism | Must-mirror details |
|
||
|---|---|---|
|
||
| 962 | cpp namespace prefix stack (#1291) | named `namespace_definition` pushes its name (C++17 `a::b` as written) onto the QN prefix while walking children; anonymous falls through bare |
|
||
| 2795 | C file-scope variables | only when NO function ancestor; iterate declarators; accept ONLY init_declarator / pointer_declarator / array_declarator — a BARE identifier declarator is a macro-prototype misparse, skip (loses uninit scalars by design); name via cDeclaratorIdentifier; signature `= <first 100 chars>`; kind constant/variable via isConst |
|
||
| 4313 | explicit operator calls (#1247) | callee = `function` field + ERROR-wrapped `operator_name` sibling; compact symbolic spacing (`operator *`→`operator*`, word forms keep space); receiver `->`→`.`; DROP unless receiver is `this` (bare name) or simple identifier/member chain (silent miss over wrong edge) |
|
||
| ~4340 | field_expression method calls | `recv.method`/`ptr->method` → `recv.method`; SKIP_RECEIVERS {self,this,cls,super} → bare name; LITERAL receiver → emit nothing (#1230) |
|
||
| 4398 | call-result receivers (#645/#608) | receiver is call_expression → `<innerCallee>().<method>` re-encode (c AND cpp in the gate list) |
|
||
| 4534 | template-arg strip on callees | callee contains `<` and NOT `operator` → stripCppTemplateArgs (CUDA launch sites post-blank take this shape) |
|
||
| 4545 | local fn-ptr call fan-out (#932-adjacent) | bare-identifier callee found in cppLocalFnPtrs[callerId] → emit one `calls` ref PER recorded target, suppress the local name |
|
||
| 5173 | stack construction (#1035) | cpp `declaration` where `type` ∈ {type_identifier, template_type, qualified_identifier} and any init_declarator has `value` ∈ {argument_list, initializer_list} → extractInstantiation |
|
||
| 5183 | fn-ptr binding recording | inside a body: `declaration>init_declarator` (identifier declarator) or `assignment_expression` (identifier left); value must be pointer_expression whose child(0) is `&`; target ∈ {identifier, template_function, qualified_identifier}, template-stripped; per-callerId map of per-local Sets (branch reassignments accumulate) |
|
||
| 5408 | base_class_clause → extends (#1043) | per base: type_identifier / qualified_identifier / template_type, stripCppTemplateArgs'd; access-specifier keywords skipped |
|
||
| 4740 | static member refs — **cpp only** (c not in STATIC_MEMBER_LANGS, line 345) | `Foo::BAR` value reads → `references` edge; VERIFY the MEMBER_ACCESS_TYPES shapes for qualified_identifier + the call-callee skip during the port |
|
||
| — | value-reference edges | **c: YES** (VALUE_REF_LANGS line 401), **cpp: NO**. Port the value-ref machinery for C only (crib go.rs / tsjs — shadow prune, scope stack, MAX_VALUE_REF_NODES cap, CODEGRAPH_VALUE_REFS=0 kill) |
|
||
| — | fn-ref capture (#756) | function-ref.ts:376: `c: cFamilySpec()`, `cpp: cFamilySpec({ addressOfOnly: true })`; note line ~582: `&Cls::m` exemption from the bare-ids-are-free-functions rule — read cFamilySpec fully when porting |
|
||
| 355 | INSTANTIATION_KINDS | includes new_expression → cpp `new Foo(...)` instantiates (verify the cpp entry list when porting) |
|
||
|
||
**Generic paths c/cpp share with ported languages** (already mirrored by
|
||
java.rs/python.rs/go.rs — re-verify each against c/cpp fixtures rather than
|
||
re-deriving): extractFunction/Method QN via scope stack + receiverType
|
||
(`Recv::name` like Go), struct/enum/enum_member extraction, typedef →
|
||
type_alias (+ resolveTypeAliasKind kind override), imports, docstrings
|
||
(preceding `comment` nodes — docstring.rs already handles C markers incl. the
|
||
CRLF semantics from #1329), contains edges, signature truncation in UTF-16
|
||
units, MAX_FILE_SIZE / generated-file skips, `has_error()` → `defer:`.
|
||
|
||
## Gates (per plan §5, no exceptions)
|
||
|
||
- Torture fixtures: `torture.c` (fn-ptr tables, typedef enum/struct, file-scope
|
||
consts incl. multi-declarator, macro-prototype misparse shape, value-refs) +
|
||
`torture.cpp`/`torture.hpp` (namespaces incl. C++17 nested, out-of-line
|
||
`Cls::method` defs, templates + template bases, operators incl. spaced call
|
||
sites, stack construction, local fn-ptrs, UE-macro shapes THROUGH the
|
||
hoisted preParse, `using` aliases, anonymous namespace, access specifiers).
|
||
- Parity sweeps + full-init dump-diffs byte-identical: redis + git (C),
|
||
fmt + a protobuf-class repo (C++), plus a UE-macro-heavy spot-check
|
||
(blanking-hoist parity) — then linux in cg1212 (expect parse 338s →
|
||
~120–180s at the 2c envelope; graph counts must stay 2,048,664/6,405,964).
|
||
- Deferral-rate guard <10%; suite; changelog rides the existing kernel entry.
|
||
- DEFAULT_ROUTED += c, cpp only after ALL of the above.
|