Check for marking virtual method due to base only when state changes (#3073)

Instead of checking every virtual method to see if it should be kept due
to a base method every iteration of the MarkStep pipeline, check each
method only when its relevant state has changed. 

Co-authored-by: Sven Boemer <sbomer@gmail.com>

3 files changed, 19 insertions, 15 deletions

diff --git a/test/Mono.Linker.Tests.Cases/Attributes/TypeWithDynamicInterfaceCastableImplementationAttributeIsKept.cs b/test/Mono.Linker.Tests.Cases/Attributes/TypeWithDynamicInterfaceCastableImplementationAttributeIsKept.cs
index 7065930ac..c6dd27cb5 100644
--- a/test/Mono.Linker.Tests.Cases/Attributes/TypeWithDynamicInterfaceCastableImplementationAttributeIsKept.cs
+++ b/test/Mono.Linker.Tests.Cases/Attributes/TypeWithDynamicInterfaceCastableImplementationAttributeIsKept.cs
@@ -16,6 +16,8 @@ namespace Mono.Linker.Tests.Cases.Attributes
 	[KeptMemberInAssembly ("impl", "Mono.Linker.Tests.Cases.Attributes.Dependencies.IReferencedAssemblyImpl", "Foo()")]
 	[KeptInterfaceOnTypeInAssembly ("impl", "Mono.Linker.Tests.Cases.Attributes.Dependencies.IReferencedAssemblyImpl",
 		"interface", "Mono.Linker.Tests.Cases.Attributes.Dependencies.IReferencedAssembly")]
+	[SetupLinkerTrimMode ("link")]
+	[IgnoreDescriptors (false)]
 	public class TypeWithDynamicInterfaceCastableImplementationAttributeIsKept
 	{
 		public static void Main ()
@@ -54,6 +56,7 @@ namespace Mono.Linker.Tests.Cases.Attributes
 #if NETCOREAPP
 	[Kept]
 	[KeptMember (".ctor()")]
+	[KeptInterface (typeof (IDynamicInterfaceCastable))]
 	class Foo : IDynamicInterfaceCastable
 	{
 		[Kept]
@@ -74,6 +77,7 @@ namespace Mono.Linker.Tests.Cases.Attributes
 
 	[Kept]
 	[KeptMember (".ctor()")]
+	[KeptInterface (typeof (IDynamicInterfaceCastable))]
 	class DynamicCastableImplementedInOtherAssembly : IDynamicInterfaceCastable
 	{
 		[Kept]
diff --git a/test/Mono.Linker.Tests.Cases/Inheritance.Interfaces/InterfaceVariants.cs b/test/Mono.Linker.Tests.Cases/Inheritance.Interfaces/InterfaceVariants.cs
index 347c3a6a0..b19208bd5 100644
--- a/test/Mono.Linker.Tests.Cases/Inheritance.Interfaces/InterfaceVariants.cs
+++ b/test/Mono.Linker.Tests.Cases/Inheritance.Interfaces/InterfaceVariants.cs
@@ -21,16 +21,21 @@ namespace Mono.Linker.Tests.Cases.Inheritance.Interfaces
 			t = typeof (UninstantiatedPublicClassWithPrivateInterface);
 			t = typeof (ImplementsUsedStaticInterface.InterfaceMethodUnused);
 
-			ImplementsUnusedStaticInterface.Test (); ;
+			ImplementsUnusedStaticInterface.Test ();
 			GenericMethodThatCallsInternalStaticInterfaceMethod
 				<ImplementsUsedStaticInterface.InterfaceMethodUsedThroughInterface> ();
 			// Use all public interfaces - they're marked as public only to denote them as "used"
 			typeof (IPublicInterface).RequiresPublicMethods ();
 			typeof (IPublicStaticInterface).RequiresPublicMethods ();
-			var ___ = new InstantiatedClassWithInterfaces ();
+			_ = new InstantiatedClassWithInterfaces ();
+			MarkIFormattable (null);
 		}
 
 		[Kept]
+		static void MarkIFormattable (IFormattable x)
+		{ }
+
+		[Kept]
 		internal static void GenericMethodThatCallsInternalStaticInterfaceMethod<T> () where T : IStaticInterfaceUsed
 		{
 			T.StaticMethodUsedThroughInterface ();
@@ -113,8 +118,8 @@ namespace Mono.Linker.Tests.Cases.Inheritance.Interfaces
 			}
 		}
 
+		// Interfaces are kept despite being uninstantiated because it is relevant to variant casting
 		[Kept]
-		[KeptInterface (typeof (IEnumerator))]
 		[KeptInterface (typeof (IPublicInterface))]
 		[KeptInterface (typeof (IPublicStaticInterface))]
 		[KeptInterface (typeof (ICopyLibraryInterface))]
@@ -151,18 +156,12 @@ namespace Mono.Linker.Tests.Cases.Inheritance.Interfaces
 			static void IInternalStaticInterface.ExplicitImplementationInternalStaticInterfaceMethod () { }
 
 
-			[Kept]
-			[ExpectBodyModified]
 			bool IEnumerator.MoveNext () { throw new PlatformNotSupportedException (); }
 
-			[Kept]
 			object IEnumerator.Current {
-				[Kept]
-				[ExpectBodyModified]
 				get { throw new PlatformNotSupportedException (); }
 			}
 
-			[Kept]
 			void IEnumerator.Reset () { }
 
 			[Kept]
@@ -198,7 +197,6 @@ namespace Mono.Linker.Tests.Cases.Inheritance.Interfaces
 		}
 
 		[Kept]
-		[KeptInterface (typeof (IEnumerator))]
 		[KeptInterface (typeof (IPublicInterface))]
 		[KeptInterface (typeof (IPublicStaticInterface))]
 		[KeptInterface (typeof (ICopyLibraryInterface))]
@@ -235,13 +233,10 @@ namespace Mono.Linker.Tests.Cases.Inheritance.Interfaces
 
 			static void IInternalStaticInterface.ExplicitImplementationInternalStaticInterfaceMethod () { }
 
-			[Kept]
 			bool IEnumerator.MoveNext () { throw new PlatformNotSupportedException (); }
 
-			[Kept]
-			object IEnumerator.Current { [Kept] get { throw new PlatformNotSupportedException (); } }
+			object IEnumerator.Current { get { throw new PlatformNotSupportedException (); } }
 
-			[Kept]
 			void IEnumerator.Reset () { }
 
 			[Kept]
diff --git a/test/Mono.Linker.Tests.Cases/Inheritance.Interfaces/StaticInterfaceMethods/UnusedInterfacesInPreservedScope.cs b/test/Mono.Linker.Tests.Cases/Inheritance.Interfaces/StaticInterfaceMethods/UnusedInterfacesInPreservedScope.cs
index a03a28bd2..35ae2dda0 100644
--- a/test/Mono.Linker.Tests.Cases/Inheritance.Interfaces/StaticInterfaceMethods/UnusedInterfacesInPreservedScope.cs
+++ b/test/Mono.Linker.Tests.Cases/Inheritance.Interfaces/StaticInterfaceMethods/UnusedInterfacesInPreservedScope.cs
@@ -37,10 +37,15 @@ namespace Mono.Linker.Tests.Cases.Inheritance.Interfaces.StaticInterfaceMethods
 			public int InstanceMethod () => 0;
 		}
 
+		// Keep MyType without marking it relevant to variant casting
+		[Kept]
+		static void KeepMyType (MyType x)
+		{ }
+
 		[Kept]
 		static void Test ()
 		{
-			var x = typeof (MyType); // The only use of MyType
+			KeepMyType (null);
 		}
 	}
 }