ADD: support of fp16 python inference backend

Signed-off-by: Sayan Protasov <[email protected]>

onnx_tensorrt/backend.py

@@ -32,7 +32,7 @@ def count_trailing_ones(vals):
 
 class TensorRTBackendRep(BackendRep):
     def __init__(self, model, device,
-            max_workspace_size=None, serialize_engine=False, verbose=False, **kwargs):
+            max_workspace_size=None, serialize_engine=False, verbose=False, fp16=False, **kwargs):
         if not isinstance(device, Device):
             device = Device(device)
         self._set_device(device)
@@ -44,8 +44,12 @@ def __init__(self, model, device,
         self.shape_tensor_inputs = []
         self.serialize_engine = serialize_engine
         self.verbose = verbose
+        self.fp16 = fp16
         self.dynamic = False
 
+        if self.fp16:
+            self.config.set_flag(trt.BuilderFlag.FP16)
+
         if self.verbose:
             print(f'\nRunning {model.graph.name}...')
             TRT_LOGGER.min_severity = trt.Logger.VERBOSE