Add amax and amin with tests (#33)

* Add amax and amin with tests

aten/src/ATen/native/mps/operations/ReduceOps.mm

@@ -220,6 +220,15 @@ void set_axes_and_shapes(const Tensor& input_t,
                                                            axes:axes
                                                            name:nil];
           }
+          else if(reduction_type == "amax") {
+            castOutputTensor = [mpsGraph reductionMaximumWithTensor:inputTensor
+                                                               axes:axes
+                                                               name:nil];
+          } else if(reduction_type == "amin") {
+            castOutputTensor = [mpsGraph reductionMinimumWithTensor:inputTensor
+                                                               axes:axes
+                                                               name:nil];
+          }
 
           MPSGraphTensor* outputTensor = nil;
 
@@ -294,6 +303,24 @@ inline ScalarType get_dtype_from_self(
   return src_type;
 }
 
+TORCH_IMPL_FUNC(amax_out_mps)
+   (const Tensor& input_t,
+    IntArrayRef dim,
+    bool keepdim,
+    const Tensor& output_t) {
+
+    reduction_out_mps(input_t, dim, keepdim, c10::nullopt, output_t, "amax", "amax_out_mps");
+}
+
+TORCH_IMPL_FUNC(amin_out_mps)
+   (const Tensor& input_t,
+    IntArrayRef dim,
+    bool keepdim,
+    const Tensor& output_t) {
+
+    reduction_out_mps(input_t, dim, keepdim, c10::nullopt, output_t, "amin", "amin_out_mps");
+}
+
 Tensor prod_mps(const Tensor &self, c10::optional<ScalarType> opt_dtype) {
 
   auto num_dims = self.dim();

aten/src/ATen/native/native_functions.yaml

@@ -3121,6 +3121,7 @@
   structured: True
   dispatch:
     CPU, CUDA: amax_out
+    MPS: amax_out_mps
 
 # Return: (Tensor output, Tensor indices)
 - func: max_pool1d_with_indices(Tensor self, int[1] kernel_size, int[1] stride=[], int[1] padding=0, int[1] dilation=1, bool ceil_mode=False) -> (Tensor, Tensor)
@@ -3277,6 +3278,7 @@
   structured: True
   dispatch:
     CPU, CUDA: amin_out
+    MPS: amin_out_mps
 
 # TODO: Add this function to MPS dispatch key so that we avoid declaring it in
 # native_functions.yaml

test/test_mps.py

@@ -2618,6 +2618,50 @@ def helper(shape):
 
         helper((4, 5, 6, 7))
 
+    # Test forward amax
+    def test_amax(self):
+        def helper(shape, dim, keepdim):
+            cpu_x = torch.randn(shape, device='cpu', dtype=torch.float, requires_grad=True)
+            x = cpu_x.detach().clone().to('mps').requires_grad_()
+
+            result = torch.amax(x, dim=dim, keepdim=keepdim)
+            result_cpu = torch.amax(cpu_x, dim=dim, keepdim=keepdim)
+
+            cpu_grad = torch.randn(result_cpu.shape)
+            grad = cpu_grad.to('mps')
+
+            result_cpu.backward(gradient=cpu_grad)
+            result.backward(gradient=grad)
+
+            self.assertEqual(result, result_cpu)
+            self.assertEqual(x.grad, cpu_x.grad)
+
+        for dim in ([], [0], [0, 1], [2, 3]):
+            for keepdim in [False, True]:
+                helper((2, 8, 4, 5), dim, keepdim)
+
+    # Test forward amin
+    def test_amin(self):
+        def helper(shape, dim, keepdim):
+            cpu_x = torch.randn(shape, device='cpu', dtype=torch.float, requires_grad=True)
+            x = cpu_x.detach().clone().to('mps').requires_grad_()
+
+            result = torch.amin(x, dim=dim, keepdim=keepdim)
+            result_cpu = torch.amin(cpu_x, dim=dim, keepdim=keepdim)
+
+            cpu_grad = torch.randn(result_cpu.shape)
+            grad = cpu_grad.to('mps')
+
+            result_cpu.backward(gradient=cpu_grad)
+            result.backward(gradient=grad)
+
+            self.assertEqual(result, result_cpu)
+            self.assertEqual(x.grad, cpu_x.grad)
+
+        for dim in ([], [0], [0, 1], [2, 3]):
+            for keepdim in [False, True]:
+                helper((2, 8, 4, 5), dim, keepdim)
+
     # Test minimum and maximum
     def test_minimum_maximum(self):
         def helper(n, c, h, w):