💾 Bringing the size of Native AOT Hello World under 1.44 MB

[MichalStrehovsky]

...because someone might want to put a Hello World (compiled with the default compiler settings) on a floppy. Of course we can go smaller if one starts disabling features like globalization or stack traces. But the defaults are interesting.

The theme is: type loader should not be necessary in a Hello World and we should be able to trim it.

• Improve EqualityComparer for NativeAOT #83054
• Avoid generic virtual methods in enum infrastructure #83063
• Make open method resolver pay for play #83064
• Emit leaner cctor context for preinitialized types #83065
• [ ] Limit impact of reflectable Invoke methods #83066
• Ifdef out a piece of unreachable reflection stack #83067
• Split TryGetGenericMethodComponents into two overloads #84156 This is keeping around MethodSignature support that needs type loader to do things like Equals.

  runtime/src/coreclr/nativeaot/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/ExecutionEnvironmentImplementation.MappingTables.cs

  Lines 893 to 895 in c9a7a2d

  	MethodNameAndSignature dummyNameAndSignature;
  	bool success = TypeLoaderEnvironment.Instance.TryGetGenericMethodComponents(instantiationArgument, out declaringTypeHandle, out dummyNameAndSignature, out genericMethodTypeArgumentHandles);
  	Debug.Assert(success);

  
  We should delete those lines and in the compiler emit what the else branch will handle. This will be a net improvement (search for "file format limitation" in the AOT compiler sources to find spots that deleting this will also fix)
• Switch attribute equality to the valuetype equality plan #84095 Attribute.Equals/GetHashCode. This was left unresolved in Bringing down the size of Hello World under 2 MB #80165. Asking for BaseType in the custom attribute requires type loader support to resolve the signature (similar for field signatures).

With the above (and hacks for the last two), I see default Hello World at 1.46 MB, down from 1.77 MB.

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Issue Details

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...because someone might want to put a Hello World (compiled with the default compiler settings) on a floppy. Of course we can go smaller if one starts disabling features like globalization or stack traces. But the defaults are interesting.

The theme is: type loader should not be necessary in a Hello World and we should be able to trim it.

• Improve EqualityComparer for NativeAOT #83054
• Avoid generic virtual methods in enum infrastructure #83063
• Make open method resolver pay for play #83064
• Emit leaner cctor context for preinitialized types #83065
• Limit impact of reflectable Invoke methods #83066
• Ifdef out a piece of unreachable reflection stack #83067
• This is keeping around MethodSignature support that needs type loader to do things like Equals.

  runtime/src/coreclr/nativeaot/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/ExecutionEnvironmentImplementation.MappingTables.cs

  Lines 893 to 895 in c9a7a2d

  	MethodNameAndSignature dummyNameAndSignature;
  	bool success = TypeLoaderEnvironment.Instance.TryGetGenericMethodComponents(instantiationArgument, out declaringTypeHandle, out dummyNameAndSignature, out genericMethodTypeArgumentHandles);
  	Debug.Assert(success);

  
  We should delete those lines and in the compiler emit what the else branch will handle. This will be a net improvement (search for "file format limitation" in the AOT compiler sources to find spots that deleting this will also fix)
• Attribute.Equals/GetHashCode. We need to make emission of custom attribute data conditional on attributes being consumed at all. This was left unresolved in Bringing down the size of Hello World under 2 MB #80165. Otherwise asking for BaseType in the custom attribute requires type loader support to resolve the signature (similar for field signatures).

With the above (and hacks for the last two), I see default Hello World at 1.46 MB, down from 1.77 MB.

Author:	MichalStrehovsky
Assignees:	-
Labels:	area-NativeAOT-coreclr
Milestone:	-