sgl-project--sglang/sgl-kernel/csrc/elementwise/fused_add_rms_norm_kernel.cu

/* Copyright 2025 SGLang Team. 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.
==============================================================================*/

#include <ATen/cuda/CUDAContext.h>

#include <flashinfer/norm.cuh>

#include "utils.h"

using namespace flashinfer;

void sgl_fused_add_rmsnorm(
    torch::Tensor input, torch::Tensor residual, torch::Tensor weight, double eps, bool enable_pdl) {
  CHECK_INPUT(input);
  CHECK_INPUT(residual);
  CHECK_INPUT(weight);
  auto device = input.device();
  CHECK_EQ(residual.device(), device);
  CHECK_EQ(weight.device(), device);
  CHECK_DIM(2, input);     // input: (batch_size, hidden_size)
  CHECK_DIM(2, residual);  // residual: (batch_size, hidden_size)
  CHECK_DIM(1, weight);    // weight: (hidden_size)
  CHECK_EQ(input.size(0), residual.size(0));
  CHECK_EQ(input.size(1), residual.size(1));
  CHECK_EQ(input.size(1), weight.size(0));
  unsigned int batch_size = input.size(0);
  unsigned int hidden_size = input.size(1);

  cudaStream_t torch_current_stream = at::cuda::getCurrentCUDAStream();
  // support float16, bfloat16 and float32
  DISPATCH_PYTORCH_DTYPE_TO_CTYPE_FLOAT_FP16(input.scalar_type(), c_type, [&] {
    cudaError_t status = norm::FusedAddRMSNorm(
        static_cast<c_type*>(input.data_ptr()),
        static_cast<c_type*>(residual.data_ptr()),
        static_cast<c_type*>(weight.data_ptr()),
        batch_size,
        hidden_size,
        input.stride(0),
        residual.stride(0),
        eps,
        enable_pdl,
        torch_current_stream);
    TORCH_CHECK(
        status == cudaSuccess, "FusedAddRMSNorm failed with error code " + std::string(cudaGetErrorString(status)));
    return true;
  });
}