Fix handling of constrained method calls from shared generic code (#2527)

Don't track runtime determined dependencies if we're generating a call
to a constrained method.

The more complicated case is tracked in #2526.

2 files changed, 43 insertions, 1 deletions

diff --git a/src/JitInterface/src/CorInfoImpl.cs b/src/JitInterface/src/CorInfoImpl.cs
index 2064ed4de..89b8d6a7a 100644
--- a/src/JitInterface/src/CorInfoImpl.cs
+++ b/src/JitInterface/src/CorInfoImpl.cs
@@ -2659,7 +2659,11 @@ namespace Internal.JitInterface
                     // to abort the inlining attempt if the inlinee does any generic lookups.
                     bool inlining = contextMethod != MethodBeingCompiled;
 
-                    if (targetMethod.IsSharedByGenericInstantiations && !inlining)
+                    // If we resolved a constrained call, calling GetRuntimeDeterminedObjectForToken below would
+                    // result in getting back the unresolved target. Don't capture runtime determined dependencies
+                    // in that case and rely on the dependency analysis computing them based on seeing a call to the
+                    // canonical method body.
+                    if (targetMethod.IsSharedByGenericInstantiations && !inlining && !resolvedConstraint)
                     {
                         MethodDesc runtimeDeterminedMethod = (MethodDesc)GetRuntimeDeterminedObjectForToken(ref pResolvedToken);
                         pResult.codePointerOrStubLookup.constLookup.addr = (void*)ObjectToHandle(
@@ -2667,6 +2671,7 @@ namespace Internal.JitInterface
                     }
                     else
                     {
+                        Debug.Assert(!forceUseRuntimeLookup);
                         pResult.codePointerOrStubLookup.constLookup.addr = (void*)ObjectToHandle(
                             _compilation.NodeFactory.MethodEntrypoint(targetMethod));
                     }
diff --git a/tests/src/Simple/Generics/Generics.cs b/tests/src/Simple/Generics/Generics.cs
index e4fc32932..603d5b792 100644
--- a/tests/src/Simple/Generics/Generics.cs
+++ b/tests/src/Simple/Generics/Generics.cs
@@ -18,6 +18,7 @@ class Program
         TestDelegateVirtualMethod.Run();
         TestDelegateInterfaceMethod.Run();
         TestThreadStaticFieldAccess.Run();
+        TestConstrainedMethodCalls.Run();
         TestNameManglingCollisionRegression.Run();
         TestUnusedGVMsDoNotCrashCompiler.Run();
 
@@ -383,6 +384,42 @@ class Program
         }
     }
 
+    class TestConstrainedMethodCalls
+    {
+        interface IFoo<T>
+        {
+            void Frob();
+        }
+
+        struct Foo<T> : IFoo<T>
+        {
+            public int FrobbedValue;
+
+            public void Frob()
+            {
+                FrobbedValue = 12345;
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static void DoFrob<T, U>(ref T t) where T : IFoo<U>
+        {
+            // Perform a constrained interface call from shared code.
+            // This should have been resolved to a direct call at compile time.
+            t.Frob();
+        }
+
+        public static void Run()
+        {
+            var foo = new Foo<object>();
+            DoFrob<Foo<object>, object>(ref foo);
+
+            // If the FrobbedValue doesn't change when we frob, we must have done box+interface call.
+            if (foo.FrobbedValue != 12345)
+                throw new Exception();
+        }
+    }
+
     //
     // Regression test for issue https://github.com/dotnet/corert/issues/1964
     //