[0-size Tensor Job2 No.55] Add 0-size Tensor support for paddle.nn.functional.cross_entropy (#74131)

* Fix * Fix * Fix * Fix

Author: co63oc

python/paddle/nn/functional/loss.py

@@ -3071,6 +3071,13 @@ def cross_entropy(
  # so, reduce_sum all directly is ok
  return _C_ops.sum(out, [], None, False)
  elif reduction == "mean":
+ # when reduction is mean, use paddle.nan
+ def _replace_nan(out):
+ return out + paddle.nan
+
+ if 0 in input.shape:
+ out = _replace_nan(out)
+ return _C_ops.mean_all(out)
  # 1. if weight==none,
  # numerator: reduce_sum all loss directly is ok causeof base_softmax_with_cross_entropy's inner logic
  # denominator: count sample num with class_index!=ignore_index

test/legacy_test/test_cross_entropy_op.py

@@ -15,7 +15,12 @@
 import unittest
 
 import numpy as np
-from op_test import OpTest, paddle_static_guard, randomize_probability
+from op_test import (
+ OpTest,
+ get_places,
+ paddle_static_guard,
+ randomize_probability,
+)
 
 import paddle
 from paddle import base
@@ -497,5 +502,25 @@ def get_cross_entropy(self):
  self.cross_entropy = np.random.random([0, 1]).astype(np.float64)
 
 
+class TestCrossEntropyOp_ZeroSize2(unittest.TestCase):
+ def test_dygraph_api(self):
+ for place in get_places():
+ paddle.disable_static(place)
+ x_np = np.random.random((16, 0)).astype(np.float64)
+ label_np = np.random.random((16, 0)).astype(np.float64)
+ x = paddle.to_tensor(x_np)
+ x.stop_gradient = False
+ label = paddle.to_tensor(label_np)
+ label.stop_gradient = False
+ out1 = paddle.nn.functional.cross_entropy(
+ x, label, soft_label=True, reduction="mean"
+ )
+ out2 = np.array(np.nan).astype(np.float64)
+ np.testing.assert_allclose(out1.numpy(), out2)
+ paddle.sum(out1).backward()
+ np.testing.assert_allclose(x.grad.shape, x.shape)
+ paddle.enable_static()
+
+
 if __name__ == "__main__":
  unittest.main()