[ILLink] Mark recursive interface implementations in MarkStep

[jtschuster]

From #99566 (comment), splitting off a simpler change that doesn't cache the recursive interfaces and doesn't use the recursive interfaces in DIM finding. This does nearly double the time it takes to trim a hello world, whereas #99566 speeds it up slightly, so I'd be concerned about timeouts if this gets merged.

[jtschuster]

The only test diff compared with #99566 comes in MultipleDimsProvidedByRecursiveInterface.cs:

@@ -16,14 +16,16 @@ namespace Mono.Linker.Tests.Cases.Inheritance.Interfaces.DefaultInterfaceMethods
        [KeptMemberInAssembly ("library.dll", typeof(Program.I0), "Method()")]
        [KeptTypeInAssembly ("library.dll", typeof(Program.I00))]
        [KeptMemberInAssembly ("library.dll", typeof(Program.I00), "Program.I0.Method()")]
-       [KeptMemberInAssembly ("library.dll", typeof(Program.I01), "Program.I0.Method()")]
+       // Bug: DIM resolution doesn't look at recursive interfaces
+       //[KeptMemberInAssembly ("library.dll", typeof(Program.I01), "Program.I0.Method()")]
        [KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.I00), "library.dll", typeof (Program.I0))]
        [KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.MyFoo), "library.dll", typeof (Program.I000))]
        [KeptTypeInAssembly ("library.dll", typeof(Program.I000))]
        [KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.I000), "library.dll", typeof (Program.I00))]
-       [KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.MyFoo), "library.dll", typeof (Program.I010))]
-       [KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.I010), "library.dll", typeof (Program.I01))]
-       [KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.I01), "library.dll", typeof (Program.I0))]
+       // Bug: DIM resolution doesn't look at recursive interfaces
+       //[KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.MyFoo), "library.dll", typeof (Program.I010))]
+       //[KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.I010), "library.dll", typeof (Program.I01))]
+       //[KeptInterfaceOnTypeInAssembly ("library.dll", typeof (Program.I01), "library.dll", typeof (Program.I0))]
 #endif
        class MultipleDimsProvidedByRecursiveInterface
        {

[sbomer]

Could we mitigate the perf impact by caching the recursive interfaces? It seems like that would still be substantially simpler than #99566.

[sbomer]

Do we need to update any other calls to type.Interfaces to look at the recursive interfaces?

[jtschuster]

Do we need to update any other calls to type.Interfaces to look at the recursive interfaces?

Yeah, there are a few places, like interface method resolution, but they might be fairly significant changes, so should we separate them out into their own PRs?

[sbomer]

Yeah, there are a few places, like interface method resolution, but they might be fairly significant changes, so should we separate them out into their own PRs?

That seems fine to me. The worst I would expect is that we miss marking some interfaces which we are already missing today.

[sbomer]

LGTM, thank you!