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#include "caffe2/core/context_gpu.h"
#include "caffe2/operators/softplus_op.h"
namespace caffe2 {
namespace {
template <typename T>
__global__ void SoftplusKernel(const int N, const T* X, T* Y) {
CUDA_1D_KERNEL_LOOP(i, N) {
Y[i] = log(exp(X[i]) + 1.0f);
}
}
template <typename T>
__global__ void
SoftplusGradientKernel(const int N, const T* Y, const T* dY, T* dX) {
CUDA_1D_KERNEL_LOOP(i, N) {
const float nexpY = exp(-Y[i]);
dX[i] = dY[i] * (1 - nexpY);
}
}
} // namespace
template <>
bool SoftplusOp<float, CUDAContext>::RunOnDevice() {
auto& X = Input(0);
DCHECK_GT(X.numel(), 0);
auto* Y = Output(0, X.sizes(), at::dtype<float>());
SoftplusKernel<float>
<<<CAFFE_GET_BLOCKS(X.numel()),
CAFFE_CUDA_NUM_THREADS,
0,
context_.cuda_stream()>>>(
X.numel(), X.data<float>(), Y->template mutable_data<float>());
return true;
}
template <>
bool SoftplusGradientOp<float, CUDAContext>::RunOnDevice() {
auto& Y = Input(0);
auto& dY = Input(1);
DCHECK_GT(Y.numel(), 0);
DCHECK_EQ(dY.numel(), Y.numel());
auto* dX = Output(0, Y.sizes(), at::dtype<float>());
SoftplusGradientKernel<float>
<<<CAFFE_GET_BLOCKS(Y.numel()),
CAFFE_CUDA_NUM_THREADS,
0,
context_.cuda_stream()>>>(
Y.numel(),
Y.data<float>(),
dY.data<float>(),
dX->template mutable_data<float>());
return true;
}
REGISTER_CUDA_OPERATOR(Softplus, SoftplusOp<float, CUDAContext>);
REGISTER_CUDA_OPERATOR(
SoftplusGradient,
SoftplusGradientOp<float, CUDAContext>);
} // namespace caffe2
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