ADD io type feature check

Author: Enrico Lupi

hls4ml/backends/vitis/passes/feature_check.py

@@ -87,3 +87,21 @@ def transform(self, model, node):
             f'WARNING: The selected order for forward and backward layers in "{node.name}" ({node.class_name}) is not '
             'supported in Vitis backend. Switching to forward layer first, backward layer last.'
         )
+
+
+class ValidateBidirectionalIoType(OptimizerPass):
+    _unrolled_layer_cls = ['Bidirectional']
+
+    def match(self, node):
+        is_bidirectional_rnn_layer = (
+            len([layer_cls for layer_cls in self._unrolled_layer_cls if layer_cls in node.class_name]) > 0
+        )
+        is_layer_io_type_stream = node.model.config.config['IOType'] != 'io_parallel'
+
+        return is_bidirectional_rnn_layer and is_layer_io_type_stream
+
+    def transform(self, model, node):
+        raise Exception(
+            f'WARNING: "{node.model.config.config["IOType"]}" IO Type is not supported in Vitis backend '
+            f'for "{node.name}" ({node.class_name}). Please use "io_parallel".'
+        )

hls4ml/backends/vitis/vitis_backend.py

@@ -19,6 +19,7 @@ def _register_flows(self):
             'vitis:validate_resource_unrolled_strategy',
             'vitis:validate_bidirectional_merge_mode',
             'vitis:validate_bidirectional_layer_order',
+            'vitis:validate_bidirectional_io_type',
         ]
         validation_flow = register_flow('validation', validation_passes, requires=['vivado:init_layers'], backend=self.name)