---
id: pr-flash-attention-2417
repo: Dao-AILab/flash-attention
pr: 2417
title: Allow compact block sparse index tensors
author: jduprat
date: '2026-04-01'
url: https://github.com/Dao-AILab/flash-attention/pull/2417
source_category: upstream-code
architectures:
- sm100
tags:
- attention
techniques: []
hardware_features: []
kernel_types:
- attention
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: f6a16e1b2216511df8670e0fa51ca205d1ee71c3
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- flash_attn/cute/block_sparsity.py
- tests/cute/test_mask_mod.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2417
head_ref_oid: 1f0985573ef47e50e6f008b9b709da763e068b34
---
# Allow compact block sparse index tensors

- Repository: `Dao-AILab/flash-attention`
- PR: [2417](https://github.com/Dao-AILab/flash-attention/pull/2417)
- Decision: `Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.`
- Reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.

## Changed Paths

- `flash_attn/cute/block_sparsity.py`
- `tests/cute/test_mask_mod.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2417`
