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

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

Review the upstream commit and path history.
If no action is needed, close this issue with a note explaining why.
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.

NET-817

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.

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Upstream change detected: dotnet/android .github/skills/read-assembly-store/src/AssemblyStore @ 8f7c4d4 #5604