[complex] add complex support for softplus

paddle/phi/kernels/cpu/activation_grad_kernel.cc

@@ -307,7 +307,8 @@ PD_REGISTER_ACTIVATION_GRAD_KERNEL(stanh_grad, STanhGradKernel)
 PD_REGISTER_ACTIVATION_GRAD_KERNEL(reciprocal_grad, ReciprocalGradKernel)
 PD_REGISTER_ACTIVATION_GRAD_KERNEL(sqrt_grad, SqrtGradKernel)
 PD_REGISTER_ACTIVATION_GRAD_KERNEL(rsqrt_grad, RsqrtGradKernel)
-PD_REGISTER_ACTIVATION_GRAD_KERNEL(softplus_grad, SoftplusGradKernel)
+PD_REGISTER_ACTIVATION_GRAD_KERNEL_WITH_COMPLEX(softplus_grad,
+                                                SoftplusGradKernel)
 
 PD_REGISTER_ACTIVATION_DOUBLE_GRAD_KERNEL(relu_double_grad,
                                           ReluDoubleGradKernel)

paddle/phi/kernels/cpu/activation_kernel.cc

@@ -201,7 +201,7 @@ PD_REGISTER_ACTIVATION_KERNEL(stanh, STanhKernel)
 PD_REGISTER_ACTIVATION_KERNEL(reciprocal, ReciprocalKernel)
 PD_REGISTER_ACTIVATION_KERNEL(sqrt, SqrtKernel)
 PD_REGISTER_ACTIVATION_KERNEL(rsqrt, RsqrtKernel)
-PD_REGISTER_ACTIVATION_KERNEL(softplus, SoftplusKernel)
+PD_REGISTER_ACTIVATION_KERNEL_WITH_COMPLEX(softplus, SoftplusKernel)
 
 PD_REGISTER_KERNEL(exp,
                    CPU,

paddle/phi/kernels/funcs/activation_functor.h

@@ -773,6 +773,31 @@ struct SoftplusGradFunctor : public BaseActivationFunctor<T> {
   static constexpr ActBwdOpFwdDeps FwdDeps() { return ActBwdOpFwdDeps::kDepX; }
 };
 
+template <typename T>
+struct SoftplusGradFunctor<ComplexType<T>>
+    : public BaseActivationFunctor<ComplexType<T>> {
+  float beta;
+  float threshold;
+  typename BaseActivationFunctor<ComplexType<T>>::AttrPair GetAttrs() {
+    return {{"beta", &beta}, {"threshold", &threshold}};
+  }
+  template <typename Device,
+            typename X,
+            typename Out,
+            typename dOut,
+            typename dX>
+  void operator()(Device d, X x, Out out UNUSED, dOut dout, dX dx) const {
+    auto x_beta = static_cast<ComplexType<T>>(beta) * x;  // NOLINT
+    dx.device(d) =
+        (x_beta > static_cast<ComplexType<T>>(threshold))
+            .select(dout,
+                    (dout / (static_cast<ComplexType<T>>(1) + (-x_beta).exp())
+                                .unaryExpr(Conj<T>())));
+  }
+
+  static constexpr ActBwdOpFwdDeps FwdDeps() { return ActBwdOpFwdDeps::kDepX; }
+};
+
 template <typename T>
 struct SoftplusDoubleGradFunctor : public BaseActivationFunctor<T> {
   float beta;
@@ -3265,7 +3290,7 @@ struct CudaSoftplusFunctor : public BaseActivationFunctor<T> {
     MPType x = static_cast<MPType>(arg_x);
     MPType b = static_cast<MPType>(beta);
     MPType t = static_cast<MPType>(threshold);
-    MPType x_beta = x * beta;
+    MPType x_beta = x * static_cast<MPType>(beta);
     return static_cast<T>(x_beta > t ? x : log(one + exp(x_beta)) / b);
   }
 };
@@ -3295,6 +3320,34 @@ struct CudaSoftplusGradFunctor : public BaseActivationFunctor<T> {
   static constexpr ActBwdOpFwdDeps FwdDeps() { return ActBwdOpFwdDeps::kDepX; }
 };
 
+template <typename T>
+struct CudaSoftplusGradFunctor<ComplexType<T>>
+    : public BaseActivationFunctor<ComplexType<T>> {
+  using MPType = typename phi::dtype::MPTypeTrait<ComplexType<T>>::Type;
+  MPType one = static_cast<MPType>(1.0f);
+  float beta;
+  float threshold;
+
+  typename BaseActivationFunctor<ComplexType<T>>::AttrPair GetAttrs() {
+    return {{"beta", &beta}, {"threshold", &threshold}};
+  }
+
+  // dx = x * beta > threshold ? dout : dout / (1 + exp(-beta * x))
+  __device__ __forceinline__ ComplexType<T> operator()(
+      const ComplexType<T> arg_dout, const ComplexType<T> arg_x) const {
+    MPType dout = static_cast<MPType>(arg_dout);
+    MPType x = static_cast<MPType>(arg_x);
+    MPType b = static_cast<MPType>(beta);
+    MPType t = static_cast<MPType>(threshold);
+    MPType x_beta = x * static_cast<MPType>(beta);
+    return x_beta > t
+               ? arg_dout
+               : static_cast<ComplexType<T>>(dout / (one + exp(-x_beta)));
+  }
+
+  static constexpr ActBwdOpFwdDeps FwdDeps() { return ActBwdOpFwdDeps::kDepX; }
+};
+
 template <typename T>
 struct CudaAtanhGradFunctor : public BaseActivationFunctor<T> {
   using MPType = typename phi::dtype::MPTypeTrait<T>::Type;

paddle/phi/kernels/gpu/activation_grad_kernel.cu

@@ -381,7 +381,8 @@ PD_REGISTER_ACTIVATION_GRAD_KERNEL(relu6_grad, Relu6GradKernel)
 PD_REGISTER_ACTIVATION_GRAD_KERNEL(mish_grad, MishGradKernel)
 PD_REGISTER_ACTIVATION_GRAD_KERNEL(stanh_grad, STanhGradKernel)
 PD_REGISTER_ACTIVATION_GRAD_KERNEL(reciprocal_grad, ReciprocalGradKernel)
-PD_REGISTER_ACTIVATION_GRAD_KERNEL(softplus_grad, SoftplusGradKernel)
+PD_REGISTER_ACTIVATION_GRAD_KERNEL_WITH_COMPLEX(softplus_grad,
+                                                SoftplusGradKernel)
 PD_REGISTER_ACTIVATION_GRAD_KERNEL(softplus_double_grad,
                                    SoftplusDoubleGradKernel)
 PD_REGISTER_ACTIVATION_GRAD_KERNEL(sqrt_grad, SqrtGradKernel)

paddle/phi/kernels/gpu/activation_kernel.cu

@@ -250,7 +250,7 @@ PD_REGISTER_ACTIVATION_KERNEL(stanh, StanhKernel)
 PD_REGISTER_ACTIVATION_KERNEL(reciprocal, ReciprocalKernel)
 PD_REGISTER_ACTIVATION_KERNEL(sqrt, SqrtKernel)
 PD_REGISTER_ACTIVATION_KERNEL(rsqrt, RsqrtKernel)
-PD_REGISTER_ACTIVATION_KERNEL(softplus, SoftplusKernel)
+PD_REGISTER_ACTIVATION_KERNEL_WITH_COMPLEX(softplus, SoftplusKernel)
 
 PD_REGISTER_KERNEL(exp,
                    GPU,

python/paddle/nn/functional/activation.py

@@ -1269,7 +1269,7 @@ def softplus(x, beta=1, threshold=20, name=None):
             \end{cases}
 
     Parameters:
-        x (Tensor): The input Tensor with data type float32, float64.
+        x (Tensor): The input Tensor with data type float32, float64, complex64, complex128.
         beta (float, optional): The value of :math:`\beta` for softplus. Default is 1
         threshold (float, optional): The value of :math:`\varepsilon` for softplus. Default is 20
         name (str, optional): For details, please refer to :ref:`api_guide_Name`. Generally, no setting is required. Default: None.
@@ -1294,7 +1294,17 @@ def softplus(x, beta=1, threshold=20, name=None):
         return _C_ops.softplus(x, beta, threshold)
     else:
         check_variable_and_dtype(
-            x, 'x', ['float16', 'uint16', 'float32', 'float64'], 'softplus'
+            x,
+            'x',
+            [
+                'float16',
+                'uint16',
+                'float32',
+                'float64',
+                'complex64',
+                'complex128',
+            ],
+            'softplus',
         )
         helper = LayerHelper('softplus', **locals())
         out = helper.create_variable_for_type_inference(x.dtype)

test/legacy_test/test_activation_op.py

@@ -3567,6 +3567,11 @@ def setUp(self):
 
         np.random.seed(1024)
         x = np.random.uniform(-1, 1, self.shape).astype(self.dtype)
+        if self.dtype == np.complex64 or self.dtype == np.complex128:
+            x = (
+                np.random.uniform(-1, 1, self.shape)
+                + 1j * np.random.uniform(-1, 1, self.shape)
+            ).astype(self.dtype)
         out = ref_softplus(x, beta, threshold)
         self.inputs = {'X': x}
         self.attrs = {'beta': beta, "threshold": threshold}
@@ -3586,6 +3591,16 @@ def init_shape(self):
         self.shape = []
 
 
+class TestSoftplus_Complex64(TestSoftplus):
+    def init_dtype(self):
+        self.dtype = np.complex64
+
+
+class TestSoftplus_Complex128(TestSoftplus):
+    def init_dtype(self):
+        self.dtype = np.complex128
+
+
 @unittest.skipIf(
     not core.is_compiled_with_cuda() or core.is_compiled_with_rocm(),
     "core is not compiled with CUDA",