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xc-llm-ascend/vllm_ascend/ops/triton/spec_decode/utils.py
pppeng 696dcc9265 [Bugfix][0.18.0] fix kernels in sample when mask is not static or draft_token_id is invalid (#8531)
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The triton kernels in sample encounter some problems, scenarios are
shown below:
1. 【expand_kernel/ rejection_random_sample_kernel/
prepare_inputs_padded_kernel】, these three operations will use
‘tl.load(prt + offsets -1, mask)’ in their implementations, but triton
compiler reports that the masks in these scenarios are not static and
contiguous. As a result, compiler will first access this memory and
apply the mask. Therefore, I modified the code to ‘tl.load(prt
+tl.maximum(offsets - 1, 0), mask)’ to ensure no -1 reads.

2. 【sample_recovered_tokens_kernel/ rejection_random_sample_kernel】,
this kernel uses draft_token_id as an address offset for the load
operation. In the PD separation scenario, if the pad token is -1,
illegal memory reads and writes can occur. Therefore, i modified the
kernel and so they can do well with -1 token.

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Signed-off-by: ppppeng <zepengliu912@qq.com>
Co-authored-by: zepengliu912@qq.com <root@localhost.localdomain>
2026-04-23 23:04:19 +08:00

66 lines
2.7 KiB
Python

# Copyright (c) 2025 Huawei Technologies Co., Ltd. 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.
# This file is a part of the vllm-ascend project.
#
# Adapted from https://github.com/vllm-project/vllm/blob/main/vllm/v1/spec_decode/utils.py
from vllm.triton_utils import tl, triton
@triton.jit(do_not_specialize=["num_reqs"])
def prepare_inputs_padded_kernel(
cu_num_draft_tokens_ptr, # [num_reqs]
valid_sampled_tokens_count_ptr, # [num_reqs]
query_start_loc_gpu_ptr, # [num_reqs + 1]
token_indices_to_sample_ptr, # [num_reqs] (output)
num_rejected_tokens_gpu_ptr,
num_reqs, # tl.int32
BLOCK_SIZE: tl.constexpr,
):
pid = tl.program_id(axis=0)
num_programs = tl.num_programs(axis=0)
# Grid-Stride Loop:
block_start_step = num_programs * BLOCK_SIZE
for block_start in tl.range(pid * BLOCK_SIZE, num_reqs, block_start_step):
offsets = block_start + tl.arange(0, BLOCK_SIZE)
mask = offsets < num_reqs
# Calculate num_draft_tokens from cu_num_draft_tokens, which is an inclusive
# cumulative sum (first entry is the first value, not zero).
cu_draft_curr = tl.load(cu_num_draft_tokens_ptr + offsets, mask=mask)
prev_indices = tl.maximum(offsets - 1, 0)
has_prev = offsets > 0
cu_draft_prev = tl.load(
cu_num_draft_tokens_ptr + prev_indices,
mask=mask & has_prev,
other=0,
)
num_draft_tokens = tl.where(has_prev, cu_draft_curr - cu_draft_prev, cu_draft_curr)
valid_count = tl.load(valid_sampled_tokens_count_ptr + offsets, mask=mask)
num_rejected = num_draft_tokens + 1 - valid_count
num_rejected = tl.where(num_draft_tokens > 0, num_rejected, 0)
# query_start_loc[req_idx + 1] is the start position of the next request,
# which is one past the last token of this request.
q_last_tok_idx = tl.load(query_start_loc_gpu_ptr + offsets + 1, mask=mask) - 1
index_to_sample = q_last_tok_idx - num_rejected
tl.store(token_indices_to_sample_ptr + offsets, index_to_sample, mask=mask)
tl.store(num_rejected_tokens_gpu_ptr + offsets, num_rejected, mask=mask)