runtime: NativeAOT on Graviton2 As `armv8.2-a` Fails to Execute

Description

When NativeAOT-compiling an application for deployment onto AWS Lambda, specifying IlcInstructionSet with the known, documented supported instruction sets for Graviton2 processors fails to execute with the error message:

The required instruction sets are not supported by the current CPU.

Reproduction Steps

For a minimal reproduction, I’m using the code from maxday’s lambda-perf cold start–testing repository, but targeting .NET 8’s NativeAOT. The meaningful parts of that are:

public class Function
{
    private static async Task Main()
    {
        await LambdaBootstrapBuilder.Create(FunctionHandler, new SourceGeneratorLambdaJsonSerializer<LambdaFunctionJsonSerializerContext>())
            .Build()
            .RunAsync();
    }

    public static StatusResponse FunctionHandler()
    {
        return new StatusResponse(statusCode: 200);
    }
}

public record StatusResponse(int statusCode);

[JsonSerializable(typeof(StatusResponse))]
public partial class LambdaFunctionJsonSerializerContext : JsonSerializerContext
{
}

…and for .csproj settings:

    <TargetFramework>net8.0</TargetFramework>
    <RuntimeIdentifier>linux-arm64</RuntimeIdentifier>
    <PublishAot>true</PublishAot>
    <AssemblyName>bootstrap</AssemblyName>

    <IlcInstructionSet>armv8.2-a</IlcInstructionSet>

Expected behavior

Because Amazon’s Graviton2 processor is documented as revision 8.2-a with support for features “fp16, rcpc, dotprod, crypto” and ilc doesn’t support “fp16” or “crypto”, I expected this:

<IlcInstructionSet>armv8.2-a,rcpc,dotprod</IlcInstructionSet>

…to compile and run. It compiled, but did not run. Figuring that maybe I was trying to add too much sauce, I tried:

<IlcInstructionSet>armv8.2-a</IlcInstructionSet>

…expecting this to compile and run. It compiled, but did not run.

Actual behavior

Upon execution, this error message is received:

The required instruction sets are not supported by the current CPU.

Regression?

No response

Known Workarounds

Leave off IlcInstructionSet, implicitly targeting revision 8.0. This does compile (natch) and run.

Configuration

I am cross-compiling for arm64 in the Docker image mcr.microsoft.com/dotnet-buildtools/prereqs:cbl-mariner-2.0-cross-arm64:

~/.dotnet/dotnet publish -p:SysRoot=/crossrootfs/arm64 -p:LinkerFlavor=lld

dotnet --version is “8.0.100-rc.1.23402.12”

Other information

I admit that I’m not certain this is a problem with the NativeAOT compiler, since I don’t know how to look into a binary and say “Aha, here is the incorrect instruction.”