[llvm] [mlir] [flang][OpenMP] Support `target enter|update|exit .. nowait` (PR #113305)

[Michael Kruse via llvm-commits]

================
@@ -7153,21 +7170,44 @@ emitTargetCall(OpenMPIRBuilder &OMPBuilder, IRBuilderBase &Builder,
   bool HasDependencies = Dependencies.size() > 0;
   bool RequiresOuterTargetTask = HasNoWait || HasDependencies;
 
+  OpenMPIRBuilder::TargetKernelArgs KArgs;
+
+  auto TaskBodyCB = [&](Value *DeviceID, Value *RTLoc,
+                        IRBuilderBase::InsertPoint TargetTaskAllocaIP) {
+    if (OutlinedFnID) {
+      // emitKernelLaunch makes the necessary runtime call to offload the
+      // kernel. We then outline all that code into a separate function
+      // ('kernel_launch_function' in the pseudo code above). This function is
+      // then called by the target task proxy function (see
+      // '@.omp_target_task_proxy_func' in the pseudo code above)
+      // "@.omp_target_task_proxy_func' is generated by
+      // emitTargetTaskProxyFunction.
+      Builder.restoreIP(OMPBuilder.emitKernelLaunch(
+          Builder, OutlinedFnID, EmitTargetCallFallbackCB, KArgs, DeviceID,
+          RTLoc, TargetTaskAllocaIP));
+    } else {
+      // When OutlinedFnID is set to nullptr, then it's not an offloading
+      // call. In this case, we execute the host implementation directly.
+      OMPBuilder.Builder.restoreIP(
+          EmitTargetCallFallbackCB(OMPBuilder.Builder.saveIP()));
+    }
+  };
+
   // If we don't have an ID for the target region, it means an offload entry
   // wasn't created. In this case we just run the host fallback directly.
   if (!OutlinedFnID) {
     if (RequiresOuterTargetTask) {
       // Arguments that are intended to be directly forwarded to an
       // emitKernelLaunch call are pased as nullptr, since OutlinedFnID=nullptr
       // results in that call not being done.
-      OpenMPIRBuilder::TargetKernelArgs KArgs;
-      Builder.restoreIP(OMPBuilder.emitTargetTask(
-          OutlinedFn, /*OutlinedFnID=*/nullptr, EmitTargetCallFallbackCB, KArgs,
-          /*DeviceID=*/nullptr, /*RTLoc=*/nullptr, AllocaIP, Dependencies,
-          HasNoWait));
+      Builder.restoreIP(OMPBuilder.emitTargetTask(TaskBodyCB,
+                                                  /*DeviceID=*/nullptr,
+                                                  /*RTLoc=*/nullptr, AllocaIP,
+                                                  Dependencies, HasNoWait));
     } else {
       Builder.restoreIP(EmitTargetCallFallbackCB(Builder.saveIP()));
     }
+
----------------
Meinersbur wrote:

```suggestion
```
[nit] unrelated change

https://github.com/llvm/llvm-project/pull/113305