---
id: pr-cccl-cub-8020
repo: NVIDIA/cccl
pr: 8020
title: Add env ReduceByKey and TransformReduce
author: gonidelis
date: '2026-03-25'
url: https://github.com/NVIDIA/cccl/pull/8020
source_category: upstream-code
architectures:
- sm100
tags:
- reduction
techniques: []
hardware_features: []
kernel_types:
- reduction
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: a8bca6166a9a65460c47f757ca977846f3175c4b
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- cub/cub/device/device_reduce.cuh
- cub/test/catch2_test_device_reduce_env.cu
- cub/test/catch2_test_device_reduce_env_api.cu
artifact_dir: evidence/pull-bundles/cccl-cub/gh-8020
head_ref_oid: e0fda58d48356b265fce13718a7bf7b1b1cc886d
---
# Add env ReduceByKey and TransformReduce

- Repository: `NVIDIA/cccl`
- PR: [8020](https://github.com/NVIDIA/cccl/pull/8020)
- 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

- `cub/cub/device/device_reduce.cuh`
- `cub/test/catch2_test_device_reduce_env.cu`
- `cub/test/catch2_test_device_reduce_env_api.cu`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-8020`
