[build] Remove unused System.IO.Hashing from runtime packs and build tasks by simonrozsival · Pull Request #13197 · dotnet/android

simonrozsival · 2026-10-19T14:58:12Z

After removing the reflection-based managed typemap (#12134) and legacy LLVM-IR typemap (#12889), several System.IO.Hashing references and helpers are no longer used:

Runtime packs: Remove unused System.IO.Hashing package references and runtime pack items from Mono.Android.csproj, Microsoft.Android.Runtime.NativeAOT.csproj, and Microsoft.Android.Runtime.Managed.proj.
Build tasks & test helpers:
- Remove dead GetXxHash and Utf16StringToBytes helpers from MonoAndroidHelper.Basic.cs and drop the now-unused System.IO.Hashing reference from Xamarin.ProjectTools.csproj.
- Move HashJavaName into tools/tmt/XamarinAppReleaseDSO_V2.cs (its only remaining caller), inline the two remaining Crc32 helpers into AssemblyStoreGenerator and CoreClrBootstrapBuilder, and delete src/Xamarin.Android.Build.Tasks/Utilities/TypeMapHelper.cs (along with its unsafe string-encoding helper and AllowUnsafeBlocks in tmt.csproj).
- Replace XxHash128 with SHA256 in MibcProfileWriter.ContentId.

Validation

./dotnet-local.sh build src/Xamarin.Android.Build.Tasks/Xamarin.Android.Build.Tasks.csproj -v minimal — Passed
./dotnet-local.sh build src/Microsoft.Android.Build.Tasks/Microsoft.Android.Build.Tasks.csproj -v minimal — Passed
./dotnet-local.sh build src/Microsoft.Android.Runtime.NativeAOT/Microsoft.Android.Runtime.NativeAOT.csproj -v minimal — Passed
./dotnet-local.sh build src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Xamarin.ProjectTools.csproj -v minimal — Passed
./dotnet-local.sh build tools/tmt/tmt.csproj -v minimal — Passed
./dotnet-local.sh test tests/Microsoft.Android.Build.BaseTasks-Tests/Microsoft.Android.Build.BaseTasks-Tests.csproj -v minimal — Passed (124 passed, 4 skipped)
./dotnet-local.sh test src/Microsoft.Android.Build.Tasks/Tests/Microsoft.Android.Build.Tasks.Tests/Microsoft.Android.Build.Tasks.Tests.csproj --filter "FullyQualifiedName~GenerateTrimmableTypeMapTests|FullyQualifiedName~CoreClrBootstrapBlobTests|FullyQualifiedName~DlopenAssemblyStoreGeneratorTests|FullyQualifiedName~ZipArchiveExTests" -v minimal — Passed (39 passed)
./dotnet-local.sh test bin/TestDebug/net10.0/Xamarin.Android.Build.Tests.dll --filter "FullyQualifiedName~GenerateNativeApplicationConfigSourcesTests|FullyQualifiedName~GenerateMibcProfileTests" -v minimal — Passed (7 passed)

Pull Request
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description
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…tasks After removing the reflection-based managed typemap (#12134) and legacy LLVM-IR typemap (#12889), several System.IO.Hashing references and helpers are no longer needed: - Remove unused System.IO.Hashing package references and runtime pack items from Mono.Android.csproj, Microsoft.Android.Runtime.NativeAOT.csproj, and Microsoft.Android.Runtime.Managed.proj. - Remove dead GetXxHash and Utf16StringToBytes helpers from MonoAndroidHelper.Basic.cs and drop the now-unused System.IO.Hashing reference from Xamarin.ProjectTools.csproj. - Move HashJavaName from TypeMapHelper.cs into tools/tmt (its only remaining caller), dropping the linked TypeMapHelper.cs and AllowUnsafeBlocks from tmt.csproj. - Replace XxHash128 with SHA256 in MibcProfileWriter.ContentId. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Inline the two remaining CRC32 helpers into AssemblyStoreGenerator and CoreClrBootstrapBuilder and remove TypeMapHelper.cs along with its unsafe string-encoding helper. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

🟢 Approval recommended

Hash compatibility is preserved, reported focused validation passed, and only an optional allocation improvement remains.

1 open issue

Avoid per-alias UTF-8 allocations in Create() · New

What changed in this PR

Removes obsolete hashing dependencies and helpers following the managed and LLVM-IR typemap removals.

Changes:

Removes unused runtime-pack and test-helper dependencies.
Moves remaining hash helpers to their consumers.
Uses SHA256 for deterministic MIBC content IDs.

File	Description
tools/tmt/XamarinAppReleaseDSO_V2.cs	Localizes Java-name hashing.
tools/tmt/tmt.csproj	Removes shared helper and unsafe setting.
src/Xamarin.Android.Build.Tasks/Utilities/TypeMapHelper.cs	Deletes obsolete shared helpers.
src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.Basic.cs	Removes unused hashing utilities.
src/Xamarin.Android.Build.Tasks/Utilities/MibcProfileWriter.cs	Switches content hashing to SHA256.
src/Xamarin.Android.Build.Tasks/Utilities/CoreClrBootstrapBuilder.cs	Localizes library-name hashing.
src/Xamarin.Android.Build.Tasks/Utilities/AssemblyStoreGenerator.cs	Localizes assembly-name hashing.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Xamarin.ProjectTools.csproj	Removes unused package reference.
src/native/clr/include/runtime-base/crc32.hh	Updates helper names in a comment.
src/Mono.Android/Mono.Android.csproj	Removes hashing dependency and copy item.
src/Microsoft.Android.Runtime.NativeAOT/Microsoft.Android.Runtime.NativeAOT.csproj	Removes unused hashing dependency.
build-tools/create-packs/Microsoft.Android.Runtime.Managed.proj	Stops packaging the hashing assembly.

_{Review effort: Balanced}

simonrozsival · 2026-10-19T20:57:41Z

/review

github-actions · 2026-10-19T20:58:37Z

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Generated by Android PR Reviewer for #13197

github-actions

✅ LGTM with one performance suggestion

Findings: 0 errors · 0 warnings · 1 suggestion

The runtime-pack dependency removal is consistent across the pack project, Mono.Android, and NativeAOT project. The localized CRC/XXHash implementations preserve the previous sentinel and encoding behavior, and the SHA-256 MIBC content ID remains deterministic and provides the 20+ bytes required by BlobContentId.FromHash.

CI had no failures at review time: 40 of 42 GitHub checks had completed successfully, with one emulator lane still running and the aggregate dotnet-android check queued.

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Generated by Android PR Reviewer for #13197 · copilot · gpt56 · 127.6 AIC · ⌖ 11.1 AIC · ⊞ 26.4K
_{Comment /review to run again}

jonathanpeppers · 2026-10-20T15:02:36Z

-		// This is only a content fingerprint, so a non cryptographic hash is fine, and unlike
-		// System.Security.Cryptography the System.IO.Hashing APIs are span based on netstandard2.0.
-		int byteCount = Encoding.UTF8.GetByteCount (fingerprint);
-		Span<byte> bytes = byteCount <= TypeMapHelper.StackallocThresholdBytes
-			? stackalloc byte [byteCount]
-			: new byte [byteCount];
-		TypeMapHelper.GetBytes (fingerprint, Encoding.UTF8, bytes);
-
-		// BlobContentId.FromHash turns hash bytes into an MVID and timestamp for us, including the
-		// RFC 4122 version and variant bits and the byte order of the Guid fields.  It reads 20
-		// bytes: 0..16 become the MVID and 16..20 become the timestamp.  XxHash128 only produces
-		// 16, so the timestamp slot repeats the first four rather than hashing the input again.
-		// This cannot be a stackalloc: FromHash only overloads on byte[] and ImmutableArray<byte>.
-		var hash = new byte [20];
-		XxHash128.Hash (bytes, hash.AsSpan (0, 16));
-		hash.AsSpan (0, 4).CopyTo (hash.AsSpan (16));
+		using var sha256 = SHA256.Create ();
+		byte[] hash = sha256.ComputeHash (Encoding.UTF8.GetBytes (fingerprint));
 		return BlobContentId.FromHash (hash);


did we lose the stackalloc above? seems like we could keep that partially?

Mibc is Release mode, so probably OK.

…oid.Build.Tasks (#13199) Context: bf732908d0250966278042dc63a5f6f7ec2ca614 Context: 12c2d57 Context: 9e66448 Context: fa7d557 Context: a3c24de `Xamarin.Android.Build.Tasks.dll` targets `netstandard2.0` so that MSBuild tasks can load in both .NET Framework (`MSBuild.exe` in Visual Studio) and .NET (`dotnet build`). Because `netstandard2.0` does not include `System.IO.Hashing` in the shared framework, referencing `System.IO.Hashing` from `Xamarin.Android.Build.Tasks.csproj` deposits the `netstandard2.0` flavor of `System.IO.Hashing.dll` (whose `Span<T>` overloads bind to `System.Memory`) into the SDK's `tools/` directory. As noted in bf73290, `net11.0` tasks had to be placed in `tools/net/Microsoft.Android.Build.Tasks.dll` so they would not resolve the `netstandard2.0` `System.IO.Hashing.dll` and fail with `MissingMethodException`. After commits 9e66448 (#13197) and a3c24de (#13198) removed unused hashing helpers and moved `<CreateAssemblyStore/>` to `Microsoft.Android.Build.Tasks.dll`, `<GenerateNativeApplicationConfigSources/>` (via `CoreClrBootstrapBuilder`) was the last remaining consumer of `System.IO.Hashing.Crc32` in `Xamarin.Android.Build.Tasks.dll`. Move `<GenerateNativeApplicationConfigSources/>` and its supporting types from `src/Xamarin.Android.Build.Tasks` (`netstandard2.0`) to `src/Microsoft.Android.Build.Tasks` (`net11.0`) so `Xamarin.Android.Build.Tasks.dll` no longer needs `System.IO.Hashing`: * Move `GenerateNativeApplicationConfigSources`, `CoreClrBootstrapBuilder`, `RuntimePropertiesParser`, and `BundleConfigSplitConfigsChecker` to `src/Microsoft.Android.Build.Tasks/` under `namespace Microsoft.Android.Tasks`. * Compute DSO cache entry hashes in `CoreClrBootstrapBuilder.Write()` directly via `System.IO.Hashing.Crc32.HashToUInt32()`, and add an explicit `System.IO.Hashing` `<PackageReference/>` to `Microsoft.Android.Build.Tasks.csproj`. * Remove the `CoreClrBootstrapBlob.cs` and `EnvironmentBuilder.cs` source links from `Xamarin.Android.Build.Tasks.csproj`, as all callers now reside in `Microsoft.Android.Build.Tasks.dll`. * Move `MonoAndroidHelper.GetAssemblyCulture()`, `ParseAndroidRuntime()`, and `GetNormalizedNativeLibraryName()` into the shared `MonoAndroidHelper.Assemblies.cs` file (using `.IsNullOrEmpty()` so `#nullable enable` compiles cleanly on `netstandard2.0` as well as `net11.0`), and move `ELFHelper.IsJniLibrary()` into `CoreClrBootstrapBuilder` while removing unused symbol-lookup helpers from `ELFHelper`. * Define `PackageNamingPolicy` in `Microsoft.Android.Tasks` so `Microsoft.Android.Build.Tasks.csproj` remains self-contained without referencing `Java.Interop.Tools.TypeNameMappings`. * Update `Xamarin.Android.Common.targets` to register `Microsoft.Android.Tasks.GenerateNativeApplicationConfigSources` from `$(_MicrosoftAndroidBuildTasksAssembly)` using the conditional `Full` (`TaskHostFactory`) / `Core` `Runtime="NET"` `<UsingTask/>` pattern from fa7d557 (#13195), and update `$(_AndroidCoreClrBootstrapTaskAssembly)` in the `_AndroidGenerateCoreClrBootstrapInputs` target to track `$(_MicrosoftAndroidBuildTasksAssembly)`. * Move `GenerateNativeApplicationConfigSourcesTests`, `RuntimePropertiesParserTests`, and `EnvironmentBuilderTests` to `Microsoft.Android.Build.Tasks.Tests`, generating synthetic 32-bit (`AndroidTargetArch.Arm`) and 64-bit (`AndroidTargetArch.Arm64`) ELF JNI libraries via `AssemblyStoreElfWriter` and `ELFReader` so the tests run standalone without requiring a native build of `libtest-jni-library.so`.

simonrozsival and others added 2 commits October 19, 2026 16:53

simonrozsival requested a review from jonathanpeppers as a code owner October 19, 2026 14:58

Copilot AI balanced review requested due to automatic review settings October 19, 2026 14:58

Copilot started reviewing on behalf of simonrozsival October 19, 2026 14:58

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Copilot AI reviewed Oct 19, 2026

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Comment thread src/Xamarin.Android.Build.Tasks/Utilities/CoreClrBootstrapBuilder.cs Resolved

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Comment thread src/Xamarin.Android.Build.Tasks/Utilities/CoreClrBootstrapBuilder.cs Resolved

simonrozsival added the ready-to-review This PR is ready to review/merge, I think any CI failures are just flaky (ignorable). label Oct 20, 2026

simonrozsival enabled auto-merge (squash) October 20, 2026 15:00

jonathanpeppers reviewed Oct 20, 2026

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jonathanpeppers approved these changes Oct 20, 2026

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simonrozsival merged commit 9e66448 into main Oct 20, 2026
42 checks passed

simonrozsival deleted the simonrozsival-system-io-hashing-packaging-analysis branch October 20, 2026 15:04

This was referenced Oct 27, 2026

Plan: remove app-build LLVM IR and the bundled binutils dependency #12940

Closed

[build] Move GenerateNativeApplicationConfigSources to Microsoft.Android.Build.Tasks #13199

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[build] Remove unused System.IO.Hashing from runtime packs and build tasks - #13197

[build] Remove unused System.IO.Hashing from runtime packs and build tasks#13197
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