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rea/docs/verification/il2cpp-generic-instances-2026-10-24.md
JANG BYUNGKUN 3ce311757d feat(il2cpp): link generic method instances behind --generic-instances (#5785)
* feat(il2cpp): read generic containers on demand and render method spec names

Generic container indices and records are demand readers on the same metadata snapshot, so links that do not ask for generic instances allocate nothing. Type rendering keeps one graph walk with its workspace, depth and cycle guards; the C#-like names and the Il2CppDumper GetMethodSpecName names are two styles over it.

* feat(il2cpp): link generic method instances with admitted rows and kept issues

generic_instances links every genericMethodTable row through methodSpecs, genericInsts and genericMethodPointers, choosing the one CodeRegistration layout whose counts bound every row. The table is reserved against the report budget before any row is resolved; rows and issues are admitted before retention, and a contradicting row stays unknown with an address-backed issue instead of failing the link. Views page the rows by definition, state, address and name, unrequested and historical collections stay unknown, and Ghidra seeds fold instances after the definitions.

* feat(il2cpp): accept --generic-instances on the CLI and describe it in tool contracts

* docs(il2cpp): describe generic method instances and their limits

* fix(il2cpp): keep issued generic rows unknown and name their row

A method spec that contradicted the metadata still reported its pointer slot as code, while the schema and provider limitation promised unknown. Such rows now keep no address, every issue carries its genericMethodTable row, the domain validator requires unknown exactly on issued rows, and shared specs name one other row instead of all of them. The row-size lower bound moves to the metadata admission owner, the hex helper is shared, and budget wording says checked rather than reserved.

* test(il2cpp): reject ambiguous generic layouts and pin budget, yield and limit paths

* fix(il2cpp): keep unmapped generic slots per row and reject undeclared arguments

Layout selection no longer requires every genericMethodPointers slot to be
mapped; each row reads its own slot, so one unmapped slot leaves only that
row unknown with an issue. Method specs whose class or method argument count
differs from the owner's declared generic container are issued and unnamed.
Fixtures now declare the containers their generic rows fill.

* fix(il2cpp): page generic method issues instead of retaining them in summaries

Summaries keep generic_methods without its issues and count them in
counts.generic_method_issues; the generic_method_issues collection pages
them by rows, indices and fields, as code_gen_modules already does. Docs
also name the method_indices filter the request schema accepts.

* fix(il2cpp): read split generic arguments per slot and method containers on demand

Generic argument arrays may span adjacent loader ranges: admit them with
hasPointerArrayCoverage and read each slot through readPointer, instead of
requiring the whole array in one mapping.

Method generic container indices are read on demand from the method record,
like type containers, so no link path allocates a per-method column. An owner
whose container index is out of range now leaves the method spec unnamed with
an issue instead of naming it unchecked.

* fix(il2cpp): report generic entries past the address space at their row

A damaged methodSpecs or genericMethodPointers pointer could make a spec or
slot address exceed 64 bits. The issue kept that address, which the address
schema rejects, so inspection failed instead of leaving the row unknown.
Check the entry range first and attach the issue to the genericMethodTable
row (or its slot field).

* chore(il2cpp): remove unrelated formatting changes

* fix: restore adb float pattern and mobile fixture from main

The merge commit's lint-staged run rewrote these two main files: oxlint --fix
dropped the escape in [+\-], which is invalid under the RegExp v flag.

* fix(il2cpp): preserve unreadable generic method identities

* docs(il2cpp): record generic-instance workflow verification

* docs(il2cpp): qualify final integration checks

---------

Co-authored-by: gensokyo-dev <342580529+gensokyo-dev@users.noreply.github.com>
2026-10-24 16:19:05 +08:00

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IL2CPP generic-instance verification, 2026-10-24

Scope and pinned implementation

PR #5785 adds opt-in static generic-method instance linking to the existing IL2CPP reader and exposes retained instances and issues to CLI/MCP views and existing Ghidra seed generation. No target is executed. The feature supports metadata 27/29/31 with a static CodeRegistration and the existing 64-bit, little-endian native image owner. Generic decoding for metadata 24/39 and builds without static registration remains explicitly unsupported; this does not remove ordinary metadata decoding for those versions.

Executed source pin: 11b84c9566027da423f2c7c3752ae2e87f0fdbb7. It includes main through d87e73f2db50be72d33a4b3c7199af35518b441c via 2718a3c775fb1a80e84066acc0f973e4ffd0e000; 219ff0b9290e3a6c7c99d40182832b9bbcf4e7e7 removes two unrelated formatting differences. This report and the query-choice paragraph are documentation-only changes after the measured source pin.

Correctness and review ownership

The contributor already corrected both earlier review findings: summaries retain an issue count rather than the issue array, and generic_method_issues owns selected/paged issue details; method generic containers are read on demand from the shared record-layout owner. No per-method generic-container vector is built when generic instances are disabled. Tests inspect the actual link-fact columns, retained views, historical omissions, malformed references, budgets and stable input identity. These are verification of the contributor's changes, not a new implementation of those fixes.

A further producing-boundary defect was reproduced: unreadable method-spec bytes became the sentinel -1, conflating unavailable data with a recorded negative index. The corrected producer preserves method: null when unreadable and keeps an actual recorded -1. The named-instance contract requires a known method; unknown unnamed rows retain null and cannot match a method-index selector. The producer regression fails before correction (112 pass, one fail). An intermediate new view expectation omitted an existing parsed offset; that test expectation was corrected without changing the product contract.

All 285 selected checks pass after the correction, covering native registration, metadata containers, generic resolution, domain views, public CLI and actual production-stdio MCP with advertised schemas. The complete task takes 164.798 s, 149.772 CPU s and 2,441.5 MiB sampled peak process-family RSS. Type/lint, full formatting and generated-document checks also pass at that source pin. An earlier integrated selection passed all 280 existing checks before adding the five new unreadable/index-contract cases. No simulated provider establishes Unity runtime dispatch, and no real Ghidra import of generated seeds was executed.

Completed MCP query comparison

Analyst question: obtain instance/issue counts and states, the first two instance identities and RVAs, and the first duplicate-spec issue, retaining both input artifact identities. Two authored version-31 inputs each contain three instances and two issues: one code row and two unknown duplicate-spec rows. The long case uses a 4,096-character type name; these are authored format fixtures, not binaries produced by Unity.

Artifact Bytes SHA-256
Small metadata 1,176 743ef4841be52734a349d9094fff971a8161ba35e9644d393c5803f84f71dc7b6cd7b
Long-name metadata 5,273 031d4e1f08219d7da4ff3fc459f8791a7e8c041234a156358361a3d3a7b6cd27
Both native ELF inputs 5,072 a6bf6e29397a389ae50f251b4167983b62cf1d9812c9108f6a17965eaa821259

complete makes one inspection call with complete detail. paged makes a summary inspection followed by two retained views: two selected instance rows/fields and one issue. Three alternating pairs per input give 12 completed tasks. Every answer agrees on the requested facts and identities; file digests are unchanged. Complete and paged Evidence objects are different workflows, so full Evidence/ID equality is not claimed. The actual SDK-converted output schemas validate with Ajv 2020. Two earlier probes used a different input-schema profile and are excluded from the paired results.

All runs use pinned Node 24.22.1, npm 11.16.0, the same locked dependencies, two allowed CPUs, a 2 GiB Node heap and production stdio with the default schema profiles. Every task starts a fresh SDK client and server. OS/file caches were primed by probes; persistent compilation-cache state was not isolated. Client and server startup, lazy schema validation, RPC trace writing and final file hashing are included in elapsed/CPU/memory costs. The first small pair was substantially slower; no cause is assigned and those completed runs remain in the ranges.

Token estimates use tokenx 1.3.0 on every reserialized JSON-RPC request, notification, catalog and reply, counting both text and structured carriers. They are estimates of transmitted payloads, not billed tokens or measured model context. Transport framing, stderr, fixture generation, token-estimation CPU, prompts, agent reasoning and model-specific conversion are outside this measure. The full catalog is 222 tools and estimates 1,003,790 tokens, including advertised output schemas. Its name/description/input-schema subset alone estimates 72,079 tokens (259,949 UTF-8 bytes); neither establishes what a particular agent sends to its model. The catalog is unchanged across these query workflows.

Input / workflow Calls Entire RPC token estimate Tool-result estimate Elapsed s, median (range) CPU s, median (range) Peak family RSS MiB, median (range)
Small / complete 1 1,012,270 7,582 20.216 (19.957–39.633) 19.992 (19.186–36.537) 946.1 (927.5–947.8)
Small / paged 3 1,018,217 13,317 25.325 (24.214–37.530) 24.853 (24.471–36.119) 1,072.7 (1,066.3–1,222.9)
Long / complete 1 1,025,889 21,201 19.211 (17.895–20.017) 19.762 (19.351–20.314) 935.7 (934.2–941.8)
Long / paged 3 1,018,217 13,317 23.724 (23.712–26.661) 23.907 (23.097–24.567) 1,108.8 (1,093.8–1,123.2)

Paging increases the small-task estimate by 5,947 (0.59%). For the long case it saves 7,672 (0.75% of the whole RPC estimate), while using more calls, CPU and memory and taking longer. The 37.2% reduction in long-case tool-result estimates is not a whole-task/context reduction. There is no general performance win here; choose complete output for small questions spanning both collections and selected pages when irrelevant retained text would otherwise dominate. The measured data does not qualify large real tables or the opt-out allocation savings numerically.

CPU is waited-child accounting. Family RSS sums recursively observed processes at 50 ms intervals; it may double-count shared pages and miss short-lived children. It is not a cgroup memory high-water mark. Host load and primed file caches limit comparability; no statistical speedup is asserted.

Real-artifact limitations

The contributor reports two private, self-built Unity 2022.3.62f3 Android arm64 version-31 builds (ordinary and identical-code folding), compared in both directions with Il2CppDumper: 5,329 instance rows, 5,285 code, 44 no-body and no issues, using 16-byte table rows. Native hashes are 580ba23b41b9470bff8ec1a06edf06294221d9b363afba3b7337632a5cef2415 and 9a0708bdbbc579f183856d3b633a16429558cd58db9863b05acbc6dcc8ae51ce; metadata is 2eb6338d81a68dffd34234d26ec1bf82c3e00c435e4d14f349ba03acc8e48b70. The oracle's Il2CppDumper version was not recorded. Those samples are not redistributed and this maintenance run did not reproduce that comparison. Other historical contributor platform checks were not rerun. Metadata 27/29 and the new unreadable/negative-index cases have authored boundary coverage only. No authentic Unity artifact, game execution, real target dispatch or Ghidra import is qualified by the 12 query tasks above.

Final integration repeat

Final executed source pin 7fdb5a29885ce05ec9181a609a37bf008b94e5df incorporates main 98ec00f4068bab894639d0d1d83ac0bfc428bcbf and the author's later cleanup 3dd803b81ccfb6b75afaa8c616693e8c4e7183d1, preserving both authors' changes. All 285 selected checks pass again: 183.057 s elapsed, 187.472 CPU s and 2,583.3 MiB sampled peak process-family RSS. Type/lint, full formatting and generated-document checks pass. This is a completed validation cost with primed file caches, not a speed comparison. The 12 paired query measurements remain pinned to the earlier source revision and are not re-labelled as measurements of this integration repeat. The final report update changes documentation only.