ptx_cp.async.cuh

//    Copyright 2024 FP6-LLM authors
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
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//        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
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// This file is copied from https://github.com/usyd-fsalab/fp6_llm/blob/ce76774bcfc26b325c1b558abcf1935026d9abbc/fp6_llm/csrc/include/ptx_cp.async.cuh

/***************************************************************************
 * Copyright 2023 The FLash-LLM 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.
 ***************************************************************************/
// Extended from CUTLASS's source code

#ifndef PTX_CP_ASYNC_CUH
#define PTX_CP_ASYNC_CUH

#include <cuda.h>
#include <cuda_fp16.h>
#include <cuda_runtime.h>

template<int SizeInBytes>
__device__ __forceinline__ void cp_async(half* smem_ptr, const half* global_ptr, bool pred_guard = true)
{
    static_assert(SizeInBytes == 16, "Size is not supported");
    unsigned smem_int_ptr = __cvta_generic_to_shared(smem_ptr);
    asm volatile("{ \n"
                 "  .reg .pred p;\n"
                 "  setp.ne.b32 p, %0, 0;\n"
                 "  @p cp.async.cg.shared.global [%1], [%2], %3;\n"
                 "}\n" ::"r"((int)pred_guard),
                 "r"(smem_int_ptr),
                 "l"(global_ptr),
                 "n"(SizeInBytes));
}

/// Establishes an ordering w.r.t previously issued cp.async instructions. Does not block.
__device__ __forceinline__ void cp_async_group_commit()
{
    asm volatile("cp.async.commit_group;\n" ::);
}

/// Blocks until all but <N> previous cp.async.commit_group operations have committed.
template<int N>
__device__ __forceinline__ void cp_async_wait_group()
{
    asm volatile("cp.async.wait_group %0;\n" ::"n"(N));
}

/// Blocks until all previous cp.async.commit_group operations have committed.
// cp.async.wait_all is equivalent to :
// cp.async.commit_group;
// cp.async.wait_group 0;
__device__ __forceinline__ void cp_async_wait_all()
{
    asm volatile("cp.async.wait_all;\n" ::);
}

#endif