[Xamarin.Android.Build.Tasks] copy all assembles to android/assets/shrunk #3950
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…runk In the case where `$(AndroidLinkMode)` is not `None`, we run a `<RemoveRegisterAttribute/>` to remove all `[Register]` attributes from `Mono.Android.dll`. This is a step to save on APK size. However, we found that the AOT compiler is seeing *two* `Mono.Android.dll` files: * obj\Debug\android\assets\Mono.Android.dll * obj\Debug\android\assets\shrunk\Mono.Android.dll @vargaz pointed out that this is bad, some of the AOT images will be linked against the wrong one and fail to load at runtime. We could possibly be silently falling back to the JIT... I first attempted to just remove the `shrunk` directory and write `Mono.Android.dll` *in place*. This idea didn't pan out: dotnet#3925 (comment) That idea broke incremental builds... So the next idea is to just copy *every assembly* into the `android\assets\shrunk` directory. Then the `AOT` compiler only operates against the `shrunk` directory. This should only happen during `Release` builds, so the build performance hit should be OK. We can also investigate removing `[Register]` from *all* assemblies in a future PR, as that will likely save further APK size from the support libraries, Google Play Services, etc.
dellis1972
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Nov 25, 2019
jonpryor
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Nov 27, 2019
…3950) In the case where `$(AndroidLinkMode)` is not `None`, we run the `<RemoveRegisterAttribute/>` task to remove all use of `[Register]` custom attributes from `Mono.Android.dll`. This is a step to save on APK size. However, we found that the AOT compiler is seeing *two* `Mono.Android.dll` files: * `obj\Debug\android\assets\Mono.Android.dll` * `obj\Debug\android\assets\shrunk\Mono.Android.dll` @vargaz pointed out that this is bad, as some of the AOT images will be linked against the wrong one and fail to load at runtime. We could possibly be silently falling back to the JIT... I first attempted to just remove the `shrunk` directory and write `Mono.Android.dll` *in place*. [This idea][0] didn't pan out, as it broke incremental builds: Skipping target "_LinkAssembliesShrink" because all output files are up-to-date with respect to the input files. ... Building target "_GenerateJavaStubs" completely. Input file "obj\Release\android\assets\UnnamedProject.dll" is newer than output file "obj\Release\stamp\_GenerateJavaStubs.stamp". ... Failed to read 'C:\src\xamarin-android\bin\TestDebug\temp\BuildAotApplication_arm64-v8a_Hybrid_True_True\obj\Release\android\assets\Mono.Android.dll' with debugging symbols. Retrying to load it without it. Error details are logged below. Mono.Cecil.Cil.SymbolsNotMatchingException: Symbols were found but are not matching the assembly at Mono.Cecil.ModuleDefinition.ReadSymbols(ISymbolReader reader, Boolean throwIfSymbolsAreNotMaching) in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/debug/external/cecil/Mono.Cecil/ModuleDefinition.cs:line 1069 at Mono.Cecil.ModuleReader.ReadSymbols(ModuleDefinition module, ReaderParameters parameters) in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/debug/external/cecil/Mono.Cecil/AssemblyReader.cs:line 111 at Mono.Cecil.ModuleReader.CreateModule(Image image, ReaderParameters parameters) in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/debug/external/cecil/Mono.Cecil/AssemblyReader.cs:line 82 at Mono.Cecil.ModuleDefinition.ReadModule(String fileName, ReaderParameters parameters) in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/debug/external/cecil/Mono.Cecil/ModuleDefinition.cs:line 1102 at Mono.Cecil.AssemblyDefinition.ReadAssembly(String fileName, ReaderParameters parameters) in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/debug/external/cecil/Mono.Cecil/AssemblyDefinition.cs:line 131 at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.ReadAssembly(String file) in C:\src\xamarin-android\external\Java.Interop\src\Java.Interop.Tools.Cecil\Java.Interop.Tools.Cecil\DirectoryAssemblyResolver.cs:line 163 Instead, just copy *every assembly* into the `android\assets\shrunk` directory, and have the `AOT` compiler only operates against the `shrunk` directory. This should only happen during `Release` builds, so the build performance hit should be OK. We can also investigate removing `[Register]` from *all* assemblies in a future PR, as that will likely save further APK size from the support libraries, Google Play Services, etc. [0]: #3925 (comment)
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In the case where
$(AndroidLinkMode)is notNone, we run a<RemoveRegisterAttribute/>to remove all[Register]attributesfrom
Mono.Android.dll. This is a step to save on APK size.However, we found that the AOT compiler is seeing two
Mono.Android.dllfiles:@vargaz pointed out that this is bad, some of the AOT images will be
linked against the wrong one and fail to load at runtime. We could
possibly be silently falling back to the JIT...
I first attempted to just remove the
shrunkdirectory and writeMono.Android.dllin place. This idea didn't pan out:#3925 (comment)
That idea broke incremental builds... So the next idea is to just copy
every assembly into the
android\assets\shrunkdirectory. Then theAOTcompiler only operates against theshrunkdirectory.This should only happen during
Releasebuilds, so the buildperformance hit should be OK. We can also investigate removing
[Register]from all assemblies in a future PR, as that will likelysave further APK size from the support libraries, Google Play
Services, etc.