Add support for Apples' Metal Performance Shaders (MPS) in pytorch

engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/engine/PtDeviceType.java

@@ -32,8 +32,10 @@ public static int toDeviceType(Device device) {
             return 0;
         } else if (Device.Type.GPU.equals(deviceType)) {
             return 1;
+        } else if ("mps".equals(deviceType)) {
+            return 13;
         } else {
-            throw new IllegalArgumentException("Unsupported device: " + device.toString());
+            throw new IllegalArgumentException("Unsupported device: " + device);
         }
     }
 
@@ -49,6 +51,8 @@ public static String fromDeviceType(int deviceType) {
                 return Device.Type.CPU;
             case 1:
                 return Device.Type.GPU;
+            case 13:
+                return "mps";
             default:
                 throw new IllegalArgumentException("Unsupported deviceType: " + deviceType);
         }

engines/pytorch/pytorch-engine/src/test/java/ai/djl/pytorch/integration/MpsTest.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
+ * OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ */
+package ai.djl.pytorch.integration;
+
+import ai.djl.Device;
+import ai.djl.ndarray.NDArray;
+import ai.djl.ndarray.NDManager;
+import ai.djl.ndarray.types.Shape;
+
+import org.testng.Assert;
+import org.testng.SkipException;
+import org.testng.annotations.Test;
+
+public class MpsTest {
+
+    @Test
+    public void testMps() {
+        if (!"aarch64".equals(System.getProperty("os.arch"))
+                || !System.getProperty("os.name").startsWith("Mac")) {
+            throw new SkipException("MPS test requires M1 macOS.");
+        }
+
+        Device device = Device.of("mps", -1);
+        try (NDManager manager = NDManager.newBaseManager(device)) {
+            NDArray array = manager.zeros(new Shape(1, 2));
+            Assert.assertEquals(array.getDevice().getDeviceType(), "mps");
+        }
+    }
+}