fix softmax_with_cross_entropy_fix bug, test=develop (#21810)

paddle/fluid/operators/softmax_with_cross_entropy_op.cu

@@ -419,6 +419,12 @@ class SoftmaxWithCrossEntropyCUDAKernel : public framework::OpKernel<T> {
     const int axis = CanonicalAxis(context.Attr<int>("axis"), rank);
     int axis_dim = logits->dims()[axis];
 
+    const int n = SizeToAxis(axis, logits->dims());
+    const int d = SizeFromAxis(axis, logits->dims());
+
+    auto* softmax_data = softmax->mutable_data<T>(context.GetPlace());
+    auto* loss_data = loss->mutable_data<T>(context.GetPlace());
+
     if (axis_dim == 1) {
       math::SetConstant<platform::CUDADeviceContext, T> set_constant;
       set_constant(context.cuda_device_context(), softmax, static_cast<T>(1));
@@ -426,12 +432,6 @@ class SoftmaxWithCrossEntropyCUDAKernel : public framework::OpKernel<T> {
       return;
     }
 
-    const int n = SizeToAxis(axis, logits->dims());
-    const int d = SizeFromAxis(axis, logits->dims());
-
-    auto* softmax_data = softmax->mutable_data<T>(context.GetPlace());
-    auto* loss_data = loss->mutable_data<T>(context.GetPlace());
-
     auto soft_label = context.Attr<bool>("soft_label");
     auto ignore_index = context.Attr<int>("ignore_index");
 

python/paddle/fluid/tests/unittests/test_softmax_with_cross_entropy_op.py

@@ -280,6 +280,23 @@ class TestSoftmaxWithCrossEntropyOpAxis4(TestSoftmaxWithCrossEntropyOp):
         self.shape = [3, 5, 7, 11]
 
 
+class TestSoftmaxWithCrossEntropyOpAxisDimEqualOne(
+        TestSoftmaxWithCrossEntropyOp):
+    """
+    Test softmax with cross entropy operator with discreate one-hot labels.
+    Given axis != -1
+    """
+
+    def initParams(self):
+        self.op_type = "softmax_with_cross_entropy"
+        self.numeric_stable_mode = True
+        self.soft_label = False
+        self.dtype = np.float64
+        self.axis = -1
+        self.ignore_index = -1
+        self.shape = [3, 5, 7, 1]
+
+
 class TestSoftmaxWithCrossEntropyOpNoCudnnFp16Axis1(
         TestSoftmaxWithCrossEntropyOpNoCudnnFp16):
     def initParams(self):