Upstream change detected: dotnet/android .github/skills/read-assembly-store/src/AssemblyStore @ 8f7c4d4

[github-actions]

Upstream Change Detected

The code at dotnet/android/.github/skills/read-assembly-store/src/AssemblyStore has a new commit since our last review.

Latest commit	8f7c4d4
Path history	View history

Our vendored copy lives in src/Sentry.Android.AssemblyReader/. We modified the upstream code significantly,
so a direct merge is unlikely to be appropriate — but the commit above may reveal logic
changes worth porting.

What to do

1. Review the upstream commit and path history.
2. If no action is needed, close this issue with a note explaining why.
3. If changes should be ported, create a follow-up task and close this issue once the work is tracked.

Automatically opened by the Watch Upstream Changes workflow.

[linear-code]

NET-817

[jamescrosswell]

Reviewed. The commit is 8f7c4d4, "[CoreCLR] Remove assembly store decompression cache" (dotnet/android#12780). It affects us, and in our favour.

Upstream remeasured the opt-in decompression cache and found it made startup worse (+162 ms TTID, +179 ms TTFD), so they removed it — and with it the content_id header field it needed, restoring assembly store format version 3 for both CoreCLR and MonoVM. Verified on dotnet/android main:

• AssemblyStoreGenerator.cs emits ASSEMBLY_STORE_FORMAT_VERSION_CORECLR_64BIT = 0x80000003
• StoreReader_V2.Classes.cs has no content_id; Header.NativeSize is a flat 5 * sizeof(uint) const
• StoreReader_V2.cs no longer lists the _V4 | ABI versions, and has dropped ASSEMBLY_STORE_FORMAT_NUMBER_MASK

main is the .NET 11 branch — there is no release/11.0.1xx, and eng/Versions.props carries AndroidPackVersion 37.2.0 with suffix rc.2. The revert (2026-09-15) predates rc.2, while version7 pins 11.0.100-rc.1 / workload 11.0.100-rc.1.26458.5 (2026-09-08), the last build that emitted v4. So v4 never shipped, and .NET 11 GA will emit v3.

Nothing needs porting into the vendored reader — our v4 support is a superset that reads v3 correctly. What did come out of the review:

• ref: Record that Android assembly store v4 never shipped #5609 corrects the vendored file headers and ATTRIBUTION.txt, which claimed v4 "ships in .NET 11", and adds synthetic-store coverage for v3 / 64-bit ABI / 32-bit CRC hash — the shape .NET 11 GA will actually produce, which had none.
• ref: Remove Android assembly store v4 support (never shipped) #5608 tracks removing the v4 code outright, once global.json moves off 11.0.100-rc.1. version7 is meant to be ready for GA, not to carry prerelease formats.

Worth recording for the stack: #5577 becomes load-bearing rather than redundant. With v4 gone, the index entry size is the only thing distinguishing a CoreCLR store from a MonoVM one — CoreCLR still writes 32-bit CRC32 name hashes on every ABI, so a .NET 11 GA arm64 store is v3, 64-bit ABI, 9-byte index entries. The pre-#5577 reader picks the hash width off the ABI bit and would read 8 bytes where there are 4. #5575's Zstandard support is unaffected; the revert removed the decompression cache, not Zstd compression.

Closing — the follow-up work is tracked in #5608.