sglang.0.4.8.post1/sglang/sgl-kernel/csrc/grammar/apply_token_bitmask_inplace...

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// Adapted from
// https://github.com/mlc-ai/xgrammar/blob/v0.1.18/python/xgrammar/kernels/apply_token_bitmask_inplace_cuda.cu
/*
* SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
* SPDX-License-Identifier: Apache-2.0
*
* 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.
*/
// clang-format off
#include <cuda_bf16.h>
#include <cuda_fp16.h>
#include <cuda_runtime.h>
#include <torch/all.h>
#include <ATen/cuda/CUDAContext.h>
#if !defined(CUDA_VERSION) || CUDA_VERSION < 12040
void ApplyTokenBitmaskInplace(at::Tensor logits, at::Tensor bitmask, at::optional<at::Tensor> indices = at::nullopt) {
TORCH_CHECK(false, "CUDA version must be >= 12.4 for ApplyTokenBitmaskInplace");
}
#else
#ifndef CUDART_INF_FP16
#define CUDART_INF_FP16 __ushort_as_half((unsigned short)0x7C00U)
#endif
#ifndef CUDART_INF_BF16
#define CUDART_INF_BF16 __ushort_as_bfloat16((unsigned short)0x7F80U)
#endif
constexpr int32_t BITS_PER_BLOCK = 32;
constexpr int32_t THREADS_PER_THREAD_BLOCK = 256;
template <typename T>
__device__ T NegativeInfinity() {
return -INFINITY;
}
template <>
__device__ __half NegativeInfinity<__half>() {
return -CUDART_INF_FP16;
}
template <>
__device__ __nv_bfloat16 NegativeInfinity<__nv_bfloat16>() {
return -CUDART_INF_BF16;
}
template <typename T, typename PackedT>
__device__ PackedT PackedNegativeInfinity() {
constexpr int kAlignment = sizeof(PackedT) / sizeof(T);
T packed[kAlignment];
#pragma unroll
for (int i = 0; i < kAlignment; i++) {
packed[i] = NegativeInfinity<T>();
}
return *reinterpret_cast<PackedT*>(packed);
}
template <typename T, typename PackedT, int32_t kBitsPerThread>
__global__ void __launch_bounds__(THREADS_PER_THREAD_BLOCK) LogitsBitmaskKernel(
T* __restrict__ logits,
const int32_t* __restrict__ bitmask,
const int32_t* __restrict__ indices,
int32_t vocab_size,
int32_t logits_stride,
int32_t bitmask_stride) {
constexpr int kAlignment = sizeof(PackedT) / sizeof(T);
constexpr uint32_t kPackedMask = (1 << kAlignment) - 1;
const int batch_idx = (indices == nullptr) ? blockIdx.y : indices[blockIdx.y];
const int block_offset = blockIdx.x * THREADS_PER_THREAD_BLOCK * kBitsPerThread;
T* logits_gmem_ptr = logits + batch_idx * logits_stride + block_offset;
const int32_t* bitmask_gmem_ptr = bitmask + batch_idx * bitmask_stride + block_offset / BITS_PER_BLOCK;
const int bitmask_inner_idx = threadIdx.x % (BITS_PER_BLOCK / kAlignment);
T logits_reg[kAlignment];
#pragma unroll
for (int offset = threadIdx.x * kAlignment; offset < THREADS_PER_THREAD_BLOCK * kBitsPerThread;
offset += THREADS_PER_THREAD_BLOCK * kAlignment) {
if (block_offset + offset >= vocab_size) {
break;
}
const uint32_t bitmask_val =
(~bitmask_gmem_ptr[offset / BITS_PER_BLOCK] >> (bitmask_inner_idx * kAlignment)) & kPackedMask;
if (bitmask_val == 0) {
continue;
}
if (bitmask_val == kPackedMask) {
*reinterpret_cast<PackedT*>(logits_gmem_ptr + offset) = PackedNegativeInfinity<T, PackedT>();
continue;
}
*reinterpret_cast<PackedT*>(logits_reg) = *reinterpret_cast<PackedT*>(logits_gmem_ptr + offset);
#pragma unroll
for (int i = 0; i < kAlignment; i++) {
if (((bitmask_val >> i) & 1)) {
logits_reg[i] = NegativeInfinity<T>();
}
}
*reinterpret_cast<PackedT*>(logits_gmem_ptr + offset) = *reinterpret_cast<PackedT*>(logits_reg);
}
}
template <typename T, typename = std::enable_if_t<std::is_integral<T>::value>>
constexpr auto CeilDiv(T numerator, T denominator) {
return (numerator + denominator - 1) / denominator;
}
template <typename T, typename PackedT>
void ApplyTokenBitmaskInplaceDispatchToBitsPerThread(
T* __restrict__ logits,
const int32_t* __restrict__ bitmask,
const int32_t* __restrict__ indices,
int32_t vocab_size,
int32_t logits_stride,
int32_t bitmask_stride,
int32_t num_rows) {
constexpr int kAlignment = sizeof(PackedT) / sizeof(T);
const int32_t num_blocks_per_row = CeilDiv(2048 / THREADS_PER_THREAD_BLOCK * 128, num_rows);
const int32_t num_bits_per_thread = CeilDiv(vocab_size, THREADS_PER_THREAD_BLOCK * num_blocks_per_row);
const dim3 block(THREADS_PER_THREAD_BLOCK);
cudaStream_t stream = at::cuda::getCurrentCUDAStream().stream();
if (num_bits_per_thread <= 4 && kAlignment <= 4) {
const dim3 grid(CeilDiv(vocab_size, THREADS_PER_THREAD_BLOCK * 4), num_rows);
LogitsBitmaskKernel<T, PackedT, 4>
<<<grid, block, 0, stream>>>(logits, bitmask, indices, vocab_size, logits_stride, bitmask_stride);
} else if (num_bits_per_thread <= 8 && kAlignment <= 8) {
const dim3 grid(CeilDiv(vocab_size, THREADS_PER_THREAD_BLOCK * 8), num_rows);
LogitsBitmaskKernel<T, PackedT, 8>
<<<grid, block, 0, stream>>>(logits, bitmask, indices, vocab_size, logits_stride, bitmask_stride);
} else if (num_bits_per_thread <= 16 && kAlignment <= 16) {
const dim3 grid(CeilDiv(vocab_size, THREADS_PER_THREAD_BLOCK * 16), num_rows);
LogitsBitmaskKernel<T, PackedT, 16>
<<<grid, block, 0, stream>>>(logits, bitmask, indices, vocab_size, logits_stride, bitmask_stride);
} else {
const dim3 grid(CeilDiv(vocab_size, THREADS_PER_THREAD_BLOCK * 32), num_rows);
LogitsBitmaskKernel<T, PackedT, 32>
<<<grid, block, 0, stream>>>(logits, bitmask, indices, vocab_size, logits_stride, bitmask_stride);
}
}
template <typename T>
void ApplyTokenBitmaskInplaceDispatchToPackedT(
T* __restrict__ logits,
const int32_t* __restrict__ bitmask,
const int32_t* __restrict__ indices,
int32_t vocab_size,
int32_t logits_stride,
int32_t bitmask_stride,
int32_t num_rows) {
if (logits_stride % (sizeof(float4) / sizeof(T)) == 0) {
ApplyTokenBitmaskInplaceDispatchToBitsPerThread<T, float4>(
logits, bitmask, indices, vocab_size, logits_stride, bitmask_stride, num_rows);
} else {
ApplyTokenBitmaskInplaceDispatchToBitsPerThread<T, T>(
logits, bitmask, indices, vocab_size, logits_stride, bitmask_stride, num_rows);
}
}
void ApplyTokenBitmaskInplace(at::Tensor logits, at::Tensor bitmask, at::optional<at::Tensor> indices = at::nullopt) {
TORCH_CHECK(logits.is_cuda(), "logits must be a CUDA tensor.");
TORCH_CHECK(logits.is_contiguous(), "logits must be contiguous.");
TORCH_CHECK(logits.dim() == 1 || logits.dim() == 2, "logits must be a 1D or 2D tensor.");
std::pair<int32_t, int32_t> logits_shape =
logits.dim() == 2 ? std::make_pair(static_cast<int32_t>(logits.size(0)), static_cast<int32_t>(logits.size(1)))
: std::make_pair(1, static_cast<int32_t>(logits.size(0)));
TORCH_CHECK(bitmask.is_cuda(), "bitmask must be a CUDA tensor.");
TORCH_CHECK(bitmask.is_contiguous(), "bitmask must be contiguous.");
TORCH_CHECK(bitmask.dim() == 1 || bitmask.dim() == 2, "bitmask must be a 1D or 2D tensor.");
std::pair<int32_t, int32_t> bitmask_shape =
bitmask.dim() == 2 ? std::make_pair(static_cast<int32_t>(bitmask.size(0)), static_cast<int32_t>(bitmask.size(1)))
: std::make_pair(1, static_cast<int32_t>(bitmask.size(0)));
TORCH_CHECK(bitmask.dtype() == torch::kInt32, "bitmask must be of type int32.");
TORCH_CHECK(
(logits_shape.second + BITS_PER_BLOCK - 1) / BITS_PER_BLOCK >= bitmask_shape.second,
"The provided logits's vocab size should be no less than the bitmask's vocab size "
"(converted from bitmask size). But got vocab size ",
logits_shape.second,
" vs bitmask size ",
bitmask_shape.second);
int vocab_size = std::min(logits_shape.second, bitmask_shape.second * BITS_PER_BLOCK);
int32_t num_rows = logits_shape.first;
int32_t* indices_ptr = nullptr;
if (indices) {
TORCH_CHECK(indices->is_cuda(), "indices must be a CUDA tensor.");
TORCH_CHECK(indices->is_contiguous(), "indices must be contiguous.");
TORCH_CHECK(indices->dim() == 1, "indices must be a 1D tensor.");
TORCH_CHECK(indices->dtype() == torch::kInt32, "indices must be of type int32.");
num_rows = indices->size(0);
indices_ptr = indices->data_ptr<int32_t>();
} else {
TORCH_CHECK(logits_shape.first == bitmask_shape.first, "logits and bitmask must have the same batch size.");
}
switch (logits.scalar_type()) {
case torch::kFloat32: {
ApplyTokenBitmaskInplaceDispatchToPackedT(
logits.data_ptr<float>(),
bitmask.data_ptr<int32_t>(),
indices_ptr,
vocab_size,
logits_shape.second,
bitmask_shape.second,
num_rows);
break;
}
case torch::kFloat16: {
ApplyTokenBitmaskInplaceDispatchToPackedT(
reinterpret_cast<__half*>(logits.data_ptr<torch::Half>()),
bitmask.data_ptr<int32_t>(),
indices_ptr,
vocab_size,
logits_shape.second,
bitmask_shape.second,
num_rows);
break;
}
case torch::kBFloat16: {
ApplyTokenBitmaskInplaceDispatchToPackedT(
reinterpret_cast<__nv_bfloat16*>(logits.data_ptr<torch::BFloat16>()),
bitmask.data_ptr<int32_t>(),
indices_ptr,
vocab_size,
logits_shape.second,
bitmask_shape.second,
num_rows);
break;
}
default:
TORCH_CHECK(false, "logits dtype must be float, half or bfloat16.");
break;
}
}
#endif
// clang-format on