[Accuracy diff No.105] Fix accuracy diff for max,amax,min,amin api (#73229)

* fix accuracy max,amax,min,amin

* fix tests

Author: ooooo-create

paddle/phi/kernels/funcs/reduce_functor.h

@@ -308,6 +308,12 @@ struct AMaxOrAMinGradFunctor {
           mask.sum(axis).reshape(dy->dimensions()).broadcast(dim);
       return;
     }
+
+    if (rank == 0) {
+      dx->device(place) = dy->broadcast(dim) * mask;
+      return;
+    }
+
     // axis is list, HANDLE_AXIS_DIM(broadcast_dim_size, rank)
     HANDLE_AXIS_DIM(3, 2);
     HANDLE_AXIS_DIM(4, 2);

test/legacy_test/test_max_min_amax_amin_op.py

@@ -139,6 +139,33 @@ def _test_dygraph(func):
     # test two minimum or maximum elements
 
 
+class TestMaxMinAmaxAminAPI_AxisWithOne1(TestMaxMinAmaxAminAPI):
+    def init_case(self):
+        self.x_np = np.random.randn(1, 5, 10).astype(np.float32)
+        self.shape = [1, 5, 10]
+        self.dtype = 'float32'
+        self.axis = 0
+        self.keepdim = False
+
+
+class TestMaxMinAmaxAminAPI_AxisWithOne2(TestMaxMinAmaxAminAPI):
+    def init_case(self):
+        self.x_np = np.random.randn(1, 5, 10).astype(np.float32)
+        self.shape = [1, 5, 10]
+        self.dtype = 'float32'
+        self.axis = 0
+        self.keepdim = True
+
+
+class TestMaxMinAmaxAminAPI_AxisWithOne3(TestMaxMinAmaxAminAPI):
+    def init_case(self):
+        self.x_np = np.random.randn(1, 1, 10).astype(np.float32)
+        self.shape = [1, 1, 10]
+        self.dtype = 'float32'
+        self.axis = (0, 1)
+        self.keepdim = False
+
+
 class TestMaxMinAmaxAminAPI_ZeroDim(TestMaxMinAmaxAminAPI):
     def init_case(self):
         self.x_np = np.array(0.5)