Do not allow generic inlining of delegate creation (dotnet#102299)

Fixes dotnet#102259.

Delegate creation requires form of lookups that are hard to express across inlined generics.

This was introduced when we started doing more generic inlining in dotnet#99265. I [suspected](dotnet#99265 (comment)) things might not be correct here but assumed we'd have test coverage for sure. _Now_ we have test coverage.

src/coreclr/jit/flowgraph.cpp

@@ -1061,14 +1061,26 @@ GenTree* Compiler::fgOptimizeDelegateConstructor(GenTreeCall* call,
  else
  {
  assert(oper != GT_FTN_ADDR);
- CORINFO_CONST_LOOKUP genericLookup;
- info.compCompHnd->getReadyToRunHelper(&ldftnToken->m_token, &pLookup.lookupKind,
- CORINFO_HELP_READYTORUN_GENERIC_HANDLE, info.compMethodHnd,
- &genericLookup);
- GenTree* ctxTree = getRuntimeContextTree(pLookup.lookupKind.runtimeLookupKind);
- call = gtNewHelperCallNode(CORINFO_HELP_READYTORUN_DELEGATE_CTOR, TYP_VOID, thisPointer,
- targetObjPointers, ctxTree);
- call->setEntryPoint(genericLookup);
+
+ if (pLookup.lookupKind.runtimeLookupKind != CORINFO_LOOKUP_NOT_SUPPORTED)
+ {
+ CORINFO_CONST_LOOKUP genericLookup;
+ info.compCompHnd->getReadyToRunHelper(&ldftnToken->m_token, &pLookup.lookupKind,
+ CORINFO_HELP_READYTORUN_GENERIC_HANDLE,
+ info.compMethodHnd, &genericLookup);
+ GenTree* ctxTree = getRuntimeContextTree(pLookup.lookupKind.runtimeLookupKind);
+ call = gtNewHelperCallNode(CORINFO_HELP_READYTORUN_DELEGATE_CTOR, TYP_VOID, thisPointer,
+ targetObjPointers, ctxTree);
+ call->setEntryPoint(genericLookup);
+ }
+ else
+ {
+ // Runtime does not support inlining of all shapes of runtime lookups
+ // Inlining has to be aborted in such a case
+ assert(compIsForInlining());
+ compInlineResult->NoteFatal(InlineObservation::CALLSITE_GENERIC_DICTIONARY_LOOKUP);
+ JITDUMP("not optimized, generic inlining restriction\n");
+ }
  }
  }
  else

src/coreclr/jit/importercalls.cpp

@@ -1005,6 +1005,10 @@ var_types Compiler::impImportCall(OPCODE opcode,
  // New inliner morph it in impImportCall.
  // This will allow us to inline the call to the delegate constructor.
  call = fgOptimizeDelegateConstructor(call->AsCall(), &exactContextHnd, ldftnInfo);
+ if (compDonotInline())
+ {
+ return TYP_UNDEF;
+ }
  }
 
  if (!bIntrinsicImported)

src/coreclr/tools/aot/ILCompiler.RyuJit/JitInterface/CorInfoImpl.RyuJit.cs

@@ -436,10 +436,17 @@ private void getReadyToRunDelegateCtorHelper(ref CORINFO_RESOLVED_TOKEN pTargetM
  {
  pLookup.lookupKind.needsRuntimeLookup = true;
 
- MethodDesc contextMethod = HandleToObject(callerHandle);
- pLookup.lookupKind.runtimeLookupKind = GetGenericRuntimeLookupKind(contextMethod);
- pLookup.lookupKind.runtimeLookupFlags = (ushort)ReadyToRunHelperId.DelegateCtor;
- pLookup.lookupKind.runtimeLookupArgs = (void*)ObjectToHandle(delegateInfo);
+ if (pTargetMethod.tokenContext != contextFromMethodBeingCompiled())
+ {
+ pLookup.lookupKind.runtimeLookupKind = CORINFO_RUNTIME_LOOKUP_KIND.CORINFO_LOOKUP_NOT_SUPPORTED;
+ }
+ else
+ {
+ MethodDesc contextMethod = HandleToObject(callerHandle);
+ pLookup.lookupKind.runtimeLookupKind = GetGenericRuntimeLookupKind(contextMethod);
+ pLookup.lookupKind.runtimeLookupFlags = (ushort)ReadyToRunHelperId.DelegateCtor;
+ pLookup.lookupKind.runtimeLookupArgs = (void*)ObjectToHandle(delegateInfo);
+ }
  }
  else
  {

src/tests/nativeaot/SmokeTests/UnitTests/Generics.cs

@@ -56,6 +56,7 @@ internal static int Run()
  TestRecursionInFields.Run();
  TestGvmLookupDependency.Run();
  Test99198Regression.Run();
+ Test102259Regression.Run();
  TestInvokeMemberCornerCaseInGenerics.Run();
  TestRefAny.Run();
  TestNullableCasting.Run();
@@ -3555,6 +3556,26 @@ public static void Run()
  }
  }
 
+ class Test102259Regression
+ {
+ class Gen<T>
+ {
+ static Func<T, object> _theval;
+
+ public static object TheFunc(object obj) => obj;
+
+ static Gen()
+ {
+ _theval = typeof(Gen<T>).GetMethod(nameof(TheFunc), BindingFlags.Public | BindingFlags.Static).CreateDelegate<Func<T, object>>().WithObjectTResult();
+ }
+ }
+
+ public static void Run()
+ {
+ new Gen<object>();
+ }
+ }
+
  class TestInvokeMemberCornerCaseInGenerics
  {
  class Generic<T>
@@ -3601,3 +3622,16 @@ public static void Run()
  }
  }
 }
+
+static class Ext
+{
+ public static Func<T, object> WithObjectTResult<T, TResult>(this Func<T, TResult> function)
+ {
+ return function.InvokeWithObjectTResult;
+ }
+
+ private static object InvokeWithObjectTResult<T, TResult>(this Func<T, TResult> func, T arg)
+ {
+ return func(arg);
+ }
+}