Skip post-async2 functions for GC stress

Author: jakobbotsch

src/coreclr/vm/gccover.cpp

@@ -261,6 +261,8 @@ void SetupGcCoverage(NativeCodeVersion nativeCodeVersion, BYTE* methodStartPtr)
     SetupAndSprinkleBreakpointsForJittedMethod(nativeCodeVersion, codeStart);
 }
 
+bool IsSpecialCaseAsyncRet(MethodDesc* pMD);
+
 void ReplaceInstrAfterCall(PBYTE instrToReplace, MethodDesc* callMD)
 {
     ReturnKind returnKind = callMD->GetReturnKind(true);
@@ -275,6 +277,15 @@ void ReplaceInstrAfterCall(PBYTE instrToReplace, MethodDesc* callMD)
     }
     _ASSERTE(IsValidReturnKind(returnKind));
 
+    if (g_pConfig->RuntimeAsyncViaJitGeneratedStateMachines())
+    {
+        if (callMD->IsAsync2Method() || (callMD->IsIntrinsic() && IsSpecialCaseAsyncRet(callMD)))
+        {
+            // Cannot encode requirement to protect async ret after call.
+            return;
+        }
+    }
+
     bool ispointerKind = IsPointerReturnKind(returnKind);
 #ifdef TARGET_ARM
     size_t instrLen = GetARMInstructionLength(instrToReplace);

src/coreclr/vm/threadsuspend.cpp

@@ -5110,7 +5110,7 @@ void STDCALL OnHijackWorker(HijackArgs * pArgs)
 #endif // HIJACK_NONINTERRUPTIBLE_THREADS
 }
 
-static bool IsSpecialCaseAsyncRet(MethodDesc* pMD)
+bool IsSpecialCaseAsyncRet(MethodDesc* pMD)
 {
     // TODO: What's the right way to do this through CoreLibBinder without
     // causing loading to happen? Also, can we just mark them as async2 in SPC,