TensorRT-LLMs/cpp/tensorrt_llm/kernels/decodingKernels.h

/*
 * Copyright (c) 2019-2023, NVIDIA CORPORATION.  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.
 */

#pragma once

#include "gptKernels.h"
#include "tensorrt_llm/kernels/decodingCommon.h"
#include <cuda_fp16.h>
#include <cuda_runtime.h>
#include <curand_kernel.h>

namespace tensorrt_llm
{

namespace kernels
{

struct gatherTreeParam
{
    // TODO rename the parameters
    int* beams = nullptr;              // [batchSize, beamWidth, maxSeqLen], workspace to put intermediate outputIds
    int* sequenceLengths = nullptr;    // [batchSize, beamWidth], total lengths of each query
    int maxSequenceLengthFinalStep = 0;
    const int* inputLengths = nullptr; // [batchSize, beamWidth]
    // response input lengths (used to slice the ids during postprocessing)
    int* responseInputLengths = nullptr;
    int maxSeqLen = 0;
    int batchSize = 0;
    int beamWidth = 0;
    const int* stepIds = nullptr;   // [maxSeqLen, batchSize, beamWidth]
    const int* parentIds = nullptr; // [maxSeqLen, batchSize, beamWidth]
    const int* endTokens = nullptr; // [batchSize], end token ids of each query
    int* outputIds = nullptr;       // the buffer to put finalized ids
    cudaStream_t stream;
    float* cumLogProbs = nullptr;   // [batchSize, beamWidth]
    float lengthPenalty = 1.0f;     // on cpu
};

/*
Do gatherTree on beam search to get final result.
*/
void invokeGatherTree(gatherTreeParam param);

void invokeFinalize(int* outputIds, int* sequenceLengths, float* cumLogProbs, float* outputLogProbs,
    const int* topKOutputIds, const int* topKSequenceLengths, const float* scores, const float* topKCumLogProbs,
    const float* topKLogProbs, const int* numBeams, const int* inputLengths, const int beamWidth, const int maxSeqLen,
    const int batchSize, cudaStream_t stream);

void invokeInitializeOutput(int* outputIds, const int* endIds, int batchBeam, int maxSeqLen, cudaStream_t stream);

void invokeCopyNextStepIds(int* nextStepIds, int** outputIdsPtr, const int* sequenceLengths, int batchSize,
    int beamWidth, int maxSeqLen, cudaStream_t stream);

//! \brief Accepts or rejects draft tokens based on the equality of draft and target tokens
//! for speculative decoding. Target token is accepted if targetToken == draftToken.
//! If number of accepted tokens N < maxDraftTokens, then function accepts N + 1 tokens of target model.
//! sequenceLengths, finishedSum and finishedFinal are modified accordingly.
//!
//! \param draftIds input buffer [batchSize, maxDraftTokens].
//! Indices of the draft tokens.
//! \param targetIds input buffer [batchSize, maxSeqLen]. Indices of the tokens decoded by the target model
//! \param contextLengths input buffer [batchSize]. Context lengths of the requests without draft tokens
//! \param numsDraftTokens input buffer [batchSize]. Number of draft tokens per request
//! \param sequenceLengths input/output buffer [batchSize] sequence lengths of the requests in batch
//! Modified in-place according to the accepted/rejected tokens
//! \param finished input buffer [maxDraftTokens + 1, batchSize] finished states at each decoding iteration
//! \param finishedFinal output buffer [batchSize] finished states after accepting/rejecting tokens
//! \param finishedSum output buffer [1] total number of requests in batch that finished the execution
//! \param batchSize batch size
//! \param beamWidth beam width
//! \param maxSeqLen maximum sequence length
//! \param maxDraftTokens maximum number of draft tokens
//! \param stream stream
void invokeAcceptDraftTokensByIds(const int* draftIds, const int* targetIds, const int* contextLengths,
    const int* numsDraftTokens, int* sequenceLengths, const FinishedState* finished, FinishedState* finishedFinal,
    int* finishedSum, int batchSize, int beamWidth, int maxSeqLen, int maxDraftTokens, cudaStream_t stream);

//! \brief Performs probabilistic acceptance of draft tokens based on their probability distributions.
//! Corrects targetLogits for the next to the last accepted token
//! according to https://openreview.net/pdf?id=C9NEblP8vS
//!
//! \param draftLogits input/output buffer [draftTokens, batchSize, beamWidth, vocabSize].
//! Initially contains token logits of the draft model.
//! \param targetLogits input/output buffer [draftTokens+1, batchSize, beamWidth, vocabSize].
//! Initially contains token logits of the target model.
//! It is modified in-place for next to the last accepted token such as
//! P'(x) = norm(max(0, P_{n+1}(x) - Q_{n+1}(x))), where N < maxDraftTokens is number of accepted tokens.
//! \param draftProbs output buffer [maxDraftTokens, batchSize, beamWidth, vocabSize].
//! Workspace buffer for token probabilities of the draft model.
//! \param targetProbs output buffer [maxDraftTokens+1, batchSize, beamWidth, vocabSize].
//! Workspace buffer for token probabilities of the target model.
//! \param numsDraftTokens input buffer [batchSize]. Number of draft tokens per request
//! \param finished output buffer [draftTokens, batchSize, beamWidth].
//! At each step sets to NOT_FINISHED if token is accepted or SKIP_DECODING if token is not accepted
//! \param curandState input buffer [batchSize]. Curand states properly
//! initialized using invokeCurandInitialize per request.
//! \param batchSize batch size
//! \param beamWidth beam width
//! \param vocabSize unpadded vocab size
//! \param vocabSizePadded padded vocab size
//! \param maxDraftTokens maximum number of draft tokens
//! \param randomThreshold True if use uniformly sampled threshold for token acceptance
//! \param constantThreshold threshold used to accept tokens if randomThreshold is false
//! \param stream stream
template <typename T>
void acceptDraftTokensByLogits(T* draftLogits, T* targetLogits, T* draftProbs, T* targetProbs,
    const int* numsDraftTokens, FinishedState* finished, curandState_t* curandState, int batchSize, int beamWidth,
    int vocabSize, int vocabSizePadded, int maxDraftTokens, bool randomThreshold, float constantThreshold,
    cudaStream_t stream);

void invokeTransposeLogProbs(float* output_log_probs, float* output_log_probs_tiled, const int* sequence_lengths,
    int batch_size, int beam_width, int max_seq_len, cudaStream_t stream);

void invokeAcceptTokens(const int* draft_tokens, const int* target_tokens, const int* context_lengths,
    const int* nums_draft_tokens, int* sequence_lengths, const bool* finished, bool* finished_final, int* finished_sum,
    int batch_size, int beam_width, int max_seq_len, int max_draft_tokens, cudaStream_t stream);

} // namespace kernels
} // namespace tensorrt_llm