Fix issue where HIP backend fails due to invalid arguments type (#216)

kernel_tuner/backends/hip.py

@@ -115,15 +115,7 @@ def ready_argument_list(self, arguments):
                 data_ctypes = dtype_map[dtype_str](arg)
                 ctype_args.append(data_ctypes)  
 
-        # Determine the types of the fields in the structure
-        field_types = [type(x) for x in ctype_args]
-        # Define a new ctypes structure with the inferred layout
-        class ArgListStructure(ctypes.Structure):
-            _fields_ = [(f'field{i}', t) for i, t in enumerate(field_types)]
-            def __getitem__(self, key):
-                return getattr(self, self._fields_[key][0])
-
-        return ArgListStructure(*ctype_args)
+        return ctype_args
 
 
     def compile(self, kernel_instance):
@@ -219,12 +211,23 @@ def run_kernel(self, func, gpu_args, threads, grid, stream=None):
         if stream is None:
             stream = self.stream
 
+        # Determine the types of the fields in the structure
+        field_types = [type(x) for x in gpu_args]
+
+        # Define a new ctypes structure with the inferred layout
+        class ArgListStructure(ctypes.Structure):
+            _fields_ = [(f'field{i}', t) for i, t in enumerate(field_types)]
+            def __getitem__(self, key):
+                return getattr(self, self._fields_[key][0])
+
+        ctype_args = ArgListStructure(*gpu_args)
+
         hip.hipModuleLaunchKernel(func, 
                                   grid[0], grid[1], grid[2], 
                                   threads[0], threads[1], threads[2],
                                   self.smem_size,
                                   stream,
-                                  gpu_args)
+                                  ctype_args)
 
     def memset(self, allocation, value, size):
         """set the memory in allocation to the value in value