Compile runtime async versions of synchronous task-returning methods

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs

@@ -664,6 +664,61 @@ private static unsafe T TransparentAwaitOfT<T>(Task<T> task)
             return default!;
         }
 
+        [BypassReadyToRun]
+        [MethodImpl(MethodImplOptions.Async)]
+        private static void TransparentAwaitWithResult(Task task)
+        {
+            if (!task.IsCompleted)
+            {
+                TailAwait();
+                TransparentAwait(task);
+                return;
+            }
+
+            TaskAwaiter.ValidateEnd(task);
+        }
+
+        [BypassReadyToRun]
+        [MethodImpl(MethodImplOptions.Async)]
+        private static void TransparentAwaitWithResult(ValueTask task)
+        {
+            if (!task.IsCompleted)
+            {
+                TailAwait();
+                TransparentAwaitValueTask(task);
+                return;
+            }
+
+            task.ThrowIfCompletedUnsuccessfully();
+        }
+
+        [BypassReadyToRun]
+        [MethodImpl(MethodImplOptions.Async)]
+        private static T TransparentAwaitWithResult<T>(Task<T> task)
+        {
+            if (!task.IsCompleted)
+            {
+                TailAwait();
+                return TransparentAwaitOfT(task);
+            }
+
+            TaskAwaiter.ValidateEnd(task);
+            return task.ResultOnSuccess;
+        }
+
+        [BypassReadyToRun]
+        [MethodImpl(MethodImplOptions.Async)]
+        private static T TransparentAwaitWithResult<T>(ValueTask<T> task)
+        {
+            if (!task.IsCompleted)
+            {
+                TailAwait();
+                return TransparentAwaitValueTaskOfT(task);
+            }
+
+            return task.Result;
+        }
+
         // Represents execution of a chain of suspended and resuming runtime
         // async functions.
         private sealed class RuntimeAsyncTask<T> : Task<T>

src/coreclr/inc/corinfo.h

@@ -716,6 +716,7 @@ enum CorInfoOptions
                                                CORINFO_GENERICS_CTXT_FROM_METHODTABLE),
     CORINFO_GENERICS_CTXT_KEEP_ALIVE        = 0x00000100, // Keep the generics context alive throughout the method even if there is no explicit use, and report its location to the CLR
     CORINFO_ASYNC_SAVE_CONTEXTS             = 0x00000200, // Runtime async method must save and restore contexts
+    CORINFO_ASYNC_VERSION                   = 0x00000400, // This is an async version whose IL belongs to a non-async method
 };
 
 //
@@ -3140,6 +3141,10 @@ class ICorStaticInfo
         CORINFO_ASYNC_INFO* pAsyncInfoOut
     ) = 0;
 
+    // Get information about which await call to use to await the return type
+    // of the non-async version of an async call.
+    virtual CORINFO_METHOD_HANDLE getAwaitReturnCall(CORINFO_METHOD_HANDLE callerHandle, CORINFO_LOOKUP* instArg) = 0;
+
     /*********************************************************************************/
     //
     // Diagnostic methods

src/coreclr/inc/icorjitinfoimpl_generated.h

@@ -507,6 +507,10 @@ void getEEInfo(
 void getAsyncInfo(
           CORINFO_ASYNC_INFO* pAsyncInfoOut) override;
 
+CORINFO_METHOD_HANDLE getAwaitReturnCall(
+          CORINFO_METHOD_HANDLE callerHandle,
+          CORINFO_LOOKUP* instArg) override;
+
 mdMethodDef getMethodDefFromMethod(
           CORINFO_METHOD_HANDLE hMethod) override;
 

src/coreclr/inc/jiteeversionguid.h

@@ -37,11 +37,11 @@
 
 #include <minipal/guid.h>
 
-constexpr GUID JITEEVersionIdentifier = { /* 2fa4c0dd-1b2b-4c3f-8a88-cc7b79c4667f */
-    0x2fa4c0dd,
-    0x1b2b,
-    0x4c3f,
-    {0x8a, 0x88, 0xcc, 0x7b, 0x79, 0xc4, 0x66, 0x7f}
+constexpr GUID JITEEVersionIdentifier = { /* dcace1ba-8b1e-45ad-890f-055c4e190ddb */
+    0xdcace1ba,
+    0x8b1e,
+    0x45ad,
+    {0x89, 0x0f, 0x05, 0x5c, 0x4e, 0x19, 0x0d, 0xdb}
   };
 
 #endif // JIT_EE_VERSIONING_GUID_H