[flang][cuda] Relax the verifier for cuf.register_kernel op

Author: clementval

flang/lib/Optimizer/Dialect/CUF/CUFOps.cpp

@@ -281,12 +281,12 @@ mlir::LogicalResult cuf::RegisterKernelOp::verify() {
 
   mlir::SymbolTable gpuSymTab(gpuMod);
   auto func = gpuSymTab.lookup<mlir::gpu::GPUFuncOp>(getKernelName());
-  if (!func)
-    return emitOpError("device function not found");
-
-  if (!func.isKernel())
-    return emitOpError("only kernel gpu.func can be registered");
-
+  if (func) {
+    // Only check if the gpu.func is found. It might be converted to LLVMFuncOp
+    // already.
+    if (!func.isKernel())
+      return emitOpError("only kernel gpu.func can be registered");
+  }
   return mlir::success();
 }
 

flang/test/Fir/cuf-invalid.fir

@@ -143,21 +143,6 @@ module attributes {gpu.container_module} {
 
 // -----
 
-module attributes {gpu.container_module} {
-  gpu.module @cuda_device_mod {
-    gpu.func @_QPsub_device1() {
-      gpu.return
-    }
-  }
-  llvm.func internal @__cudaFortranConstructor() {
-    // expected-error@+1{{'cuf.register_kernel' op device function not found}}
-    cuf.register_kernel @cuda_device_mod::@_QPsub_device2
-    llvm.return
-  }
-}
-
-// -----
-
 module attributes {gpu.container_module} {
   llvm.func internal @__cudaFortranConstructor() {
     // expected-error@+1{{'cuf.register_kernel' op gpu module not found}}