Devirtualization for Async Methods in crossgen2 resolveVirtualMethod

[jtschuster]

Currently, crossgen2's resolveVirtualMethod fails when the method is an async variant. As a result, async methods cannot currently be devirtualized and may miss optimization opportunities.

We need to implement devirtualization support for async variants of virtual methods in crossgen2.

Relevant files:

• src/coreclr/tools/Common/Compiler/DevirtualizationManager.cs
• src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCodegenCompilation.cs
• src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs

[MichalStrehovsky]

It's possible that all that's needed is to switch this line:

runtime/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCompilerContext.cs

Line 14 in f8ac08f

private readonly MetadataVirtualMethodAlgorithm _virtualMethodAlgorithm = new MetadataVirtualMethodAlgorithm();

to = new AsyncAwareVirtualMethodResolutionAlgorithm(this);