Fix device handling and logits concatenation in OliveEvaluator

- Add exception handling for unsupported devices in `device_string_to_torch_device` method.
- Correct logits concatenation in `OnnxEvaluator` by using `logits_dict` instead of `logits`.
- Initialize `logits_dict` in `PyTorchEvaluator` to handle different result types.
- Update `_inference` method in `PyTorchEvaluator` to handle different result types and concatenate logits correctly.

olive/evaluator/olive_evaluator.py

@@ -196,7 +196,11 @@ def compute_throughput(metric: Metric, latencies: Any) -> MetricResult:
 class _OliveEvaluator(OliveEvaluator):
     @staticmethod
     def device_string_to_torch_device(device: Device):
-        return torch.device("cuda") if device == Device.GPU else torch.device(device)
+        try:
+            return torch.device("cuda") if device == Device.GPU else torch.device(device)
+        except (ValueError, TypeError, RuntimeError):
+            logger.warning("Device %s is not supported in torch, fallback to CPU instead.", device)
+            return torch.device("cpu")
 
     @classmethod
     def io_bind_enabled(cls, metric: Metric, inference_settings: Dict) -> bool:
@@ -462,7 +466,7 @@ def _inference(
         if is_single_tensor_output:
             logits = torch.cat(logits, dim=0)
         else:
-            logits = {k: torch.cat(logits[k], dim=0) for k in output_names}
+            logits = {k: torch.cat(logits_dict[k], dim=0) for k in output_names}
 
         tuning_result_file = inference_settings.get("tuning_result_file")
         if tuning_result_file:
@@ -736,6 +740,7 @@ def _inference(
         preds = []
         targets = []
         logits = []
+        logits_dict = collections.defaultdict(list)
         device = _OliveEvaluator.device_string_to_torch_device(device)
         run_kwargs = metric.get_run_kwargs()
         if device:
@@ -748,15 +753,20 @@ def _inference(
             # it is expensive to convert to list and then convert back to torch tensor
             preds.append(outputs.cpu())
             targets.append(labels.cpu())
-            logits.append(
-                result.logits.cpu()
-                if not isinstance(result, torch.Tensor) and getattr(result, "logits", None) is not None
-                else result.cpu()
-            )
+            if isinstance(result, torch.Tensor):
+                logits.append(result.cpu())
+            elif isinstance(result, (list, tuple)):
+                logits.append([r.cpu() for r in result])
+            elif isinstance(result, dict):
+                for k in result:
+                    logits_dict[k].append(result[k].cpu())
         # concatenate along the batch dimension
         preds = torch.cat(preds, dim=0)
         targets = torch.cat(targets, dim=0)
-        logits = torch.cat(logits, dim=0)
+        if not logits_dict:
+            logits = torch.cat(logits, dim=0)
+        else:
+            logits = {k: torch.cat(logits_dict[k], dim=0) for k in logits_dict}
         # move model to cpu
         if device:
             session.to("cpu")

test/unit_test/evaluator/test_olive_evaluator.py

@@ -29,6 +29,7 @@
     OpenVINOEvaluator,
     PyTorchEvaluator,
     SNPEEvaluator,
+    _OliveEvaluator,
 )
 from olive.exception import OliveEvaluationError
 from olive.hardware.accelerator import Device
@@ -404,6 +405,65 @@ def test_evaluator_get_inference_session(self, metric_inference_settings, model_
                 assert metric.get_inference_settings("onnx") == metric_inference_settings
                 assert model.inference_settings == model_inference_settings
 
+    @pytest.mark.parametrize(
+        ("input_device", "torch_device"),
+        [("cpu", "cpu"), ("gpu", "cuda"), ("cuda", "cuda"), ("npu", "cpu"), ("unknown device", "cpu")],
+    )
+    def test_evaluator_unknown_device(self, input_device, torch_device):
+        assert _OliveEvaluator.device_string_to_torch_device(input_device).type == torch_device
+
+    @patch("onnxruntime.InferenceSession")
+    def test_onnx_evaluator_inference_dict_output(self, inference_session_mock):
+        mock_session = MagicMock()
+        mock_session.get_providers.return_value = ["CPUExecutionProvider"]
+        mock_session.run.return_value = ([0.5, 0.6], [0.6, 0.7])
+        inference_session_mock.return_value = mock_session
+
+        model = get_onnx_model()
+        # pylint: disable=protected-access
+        model._io_config = {
+            "input_names": ["dummy"],
+            "input_types": ["int32"],
+            "output_names": ["output_1", "output_2"],
+        }
+        metric = get_accuracy_metric(AccuracySubType.PRECISION)
+        dataloader, *_ = OliveEvaluator.get_user_config(model.framework, metric)
+        evaluator = OnnxEvaluator()
+
+        # pylint: disable=protected-access
+        outputs, *_ = evaluator._inference(
+            model,
+            metric,
+            dataloader,
+            lambda x: x["output_1"],
+        )
+        mock_session.run.assert_called_once()
+        assert set(outputs.logits.keys()) == set(model.io_config["output_names"])
+
+    def test_torch_evaluator_inference_dict_output(self):
+        import torch
+
+        model = MagicMock()
+        model.run_session.return_value = {
+            "output_1": torch.Tensor([0.5, 0.6]),
+            "output_2": torch.Tensor([0.6, 0.7]),
+        }
+        metric = MagicMock()
+        metric.get_run_kwargs.return_value = {}
+        dataloader = MagicMock()
+        dataloader.__iter__.return_value = [(torch.Tensor([1, 1]), torch.Tensor([0]))]
+        evaluator = PyTorchEvaluator()
+
+        # pylint: disable=protected-access
+        outputs, *_ = evaluator._inference(
+            model,
+            metric,
+            dataloader,
+            lambda x: x["output_1"],
+        )
+        model.run_session.assert_called_once()
+        assert set(outputs.logits.keys()) == {"output_1", "output_2"}
+
 
 class TestOliveEvaluatorConfig:
     @pytest.mark.parametrize(