[0-size Tensor No.76-79] Add 0-size Tensor support for i0

paddle/phi/kernels/cpu/i0_grad_kernel.cc

@@ -26,6 +26,10 @@ void I0GradKernel(const Context& ctx,
                   const DenseTensor& x,
                   const DenseTensor& out_grad,
                   DenseTensor* x_grad) {
+  if (x_grad && x_grad->numel() == 0) {
+    ctx.template Alloc<T>(x_grad);
+    return;
+  }
   auto size = x.numel();
   auto* x_data = x.data<T>();
   auto* out_grad_data = out_grad.data<T>();

paddle/phi/kernels/cpu/i0_kernel.cc

@@ -23,6 +23,10 @@ namespace phi {
 
 template <typename T, typename Context>
 void I0Kernel(const Context& ctx, const DenseTensor& x, DenseTensor* out) {
+  if (out && out->numel() == 0) {
+    ctx.template Alloc<T>(out);
+    return;
+  }
   const int64_t size = x.numel();
   const T* x_data = x.data<T>();
   T* out_data = ctx.template Alloc<T>(out);

paddle/phi/kernels/cpu/i0e_grad_kernel.cc

@@ -27,6 +27,11 @@ void I0eGradKernel(const Context& ctx,
                    const DenseTensor& out,
                    const DenseTensor& out_grad,
                    DenseTensor* x_grad) {
+  if (x_grad && x_grad->numel() == 0) {
+    ctx.template Alloc<T>(x_grad);
+    return;
+  }
+
   auto size = x.numel();
   auto* x_data = x.data<T>();
   auto* out_data = out.data<T>();

paddle/phi/kernels/cpu/i0e_kernel.cc

@@ -23,6 +23,10 @@ namespace phi {
 
 template <typename T, typename Context>
 void I0eKernel(const Context& ctx, const DenseTensor& x, DenseTensor* out) {
+  if (out && out->numel() == 0) {
+    ctx.template Alloc<T>(out);
+    return;
+  }
   int64_t size = x.numel();
   const T* x_data = x.data<T>();
   T* out_data = ctx.template Alloc<T>(out);

paddle/phi/kernels/cpu/i1_grad_kernel.cc

@@ -27,6 +27,10 @@ void I1GradKernel(const Context& ctx,
                   const DenseTensor& out,
                   const DenseTensor& out_grad,
                   DenseTensor* x_grad) {
+  if (x_grad && x_grad->numel() == 0) {
+    ctx.template Alloc<T>(x_grad);
+    return;
+  }
   const int64_t size = x.numel();
   const T* x_data = x.data<T>();
   const T* out_data = out.data<T>();

paddle/phi/kernels/cpu/i1_kernel.cc

@@ -23,6 +23,10 @@ namespace phi {
 
 template <typename T, typename Context>
 void I1Kernel(const Context& ctx, const DenseTensor& x, DenseTensor* out) {
+  if (out && out->numel() == 0) {
+    ctx.template Alloc<T>(out);
+    return;
+  }
   const int64_t size = x.numel();
   const T* x_data = x.data<T>();
   T* out_data = ctx.template Alloc<T>(out);

paddle/phi/kernels/cpu/i1e_grad_kernel.cc

@@ -27,6 +27,10 @@ void I1eGradKernel(const Context& ctx,
                    const DenseTensor& out,
                    const DenseTensor& out_grad,
                    DenseTensor* x_grad) {
+  if (x_grad && x_grad->numel() == 0) {
+    ctx.template Alloc<T>(x_grad);
+    return;
+  }
   const int64_t size = x.numel();
   const T* x_data = x.data<T>();
   const T* out_data = out.data<T>();

paddle/phi/kernels/cpu/i1e_kernel.cc

@@ -23,6 +23,10 @@ namespace phi {
 
 template <typename T, typename Context>
 void I1eKernel(const Context& ctx, const DenseTensor& x, DenseTensor* out) {
+  if (out && out->numel() == 0) {
+    ctx.template Alloc<T>(out);
+    return;
+  }
   const int64_t size = x.numel();
   const T* x_data = x.data<T>();
   T* out_data = ctx.template Alloc<T>(out);

test/legacy_test/test_i0_op_0size.py

@@ -0,0 +1,59 @@
+# Copyright (c) 2025 PaddlePaddle Authors. 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.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License 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.
+
+import unittest
+
+import numpy as np
+
+import paddle
+
+
+def create_test_class(op_type, dtype, shape):
+    class Cls(unittest.TestCase):
+        def test_zero_size(self):
+            numpy_tensor_1 = np.random.rand(*shape).astype(dtype)
+            paddle_x = paddle.to_tensor(numpy_tensor_1)
+            paddle_x.stop_gradient = False
+
+            paddle_api = eval(f"paddle.{op_type}")
+            paddle_out = paddle_api(paddle_x)
+            numpy_api = eval(f"scipy.special.{op_type}")
+            numpy_out = numpy_api(numpy_tensor_1)
+
+            np.testing.assert_allclose(
+                paddle_out.numpy(),
+                numpy_out,
+                1e-2,
+                1e-2,
+            )
+            np.testing.assert_allclose(
+                paddle_out.shape,
+                numpy_out.shape,
+            )
+
+    cls_name = f"{op_type}{dtype}_0SizeTest"
+    Cls.__name__ = cls_name
+    globals()[cls_name] = Cls
+
+
+op_list = ["i0", "i0e", "i1", "i1e"]
+
+for op in op_list:
+    create_test_class(op, "float32", [3, 4, 0])
+    create_test_class(op, "float64", [3, 4, 0, 3, 4])
+    create_test_class(op, "int32", [3, 4, 0])
+    create_test_class(op, "int64", [3, 4, 0, 3, 4])
+
+if __name__ == '__main__':
+    unittest.main()