---
id: pr-cccl-cub-6819
repo: NVIDIA/cccl
pr: 6819
title: Use integer promotion for `warp_reduce`
author: miscco
date: '2025-12-11'
url: https://github.com/NVIDIA/cccl/pull/6819
source_category: upstream-code
architectures:
- sm90
tags:
- arch_pipeline
- benchmark_test
- memory_primitives
- sm90
- warp reduce
techniques:
- pipeline-stages
- warp-specialization
hardware_features:
- hopper
kernel_types:
- memory
- runtime
languages:
- cuda-cpp
captured_at: '2026-05-16'
status: merged
merge_sha: a04ffc4ef546053e53e61a8bd5ef099fcf367d14
inclusion_reason: 'Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.'
changed_paths:
- cub/benchmarks/bench/reduce/warp_reduce_base.cuh
- cub/benchmarks/bench/reduce/warp_reduce_min.cu
- cub/benchmarks/bench/reduce/warp_reduce_sum.cu
- cub/cub/warp/specializations/warp_reduce_shfl.cuh
artifact_dir: evidence/pull-bundles/cccl-cub/gh-6819
head_ref_oid: 0d234b5080a90a9dfc00db4167f761f07c91a324
---
# Use integer promotion for `warp_reduce`

- Repository: `NVIDIA/cccl`
- PR: [6819](https://github.com/NVIDIA/cccl/pull/6819)
- Decision: `Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.`
- Reason: Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.

## Changed Paths

- `cub/benchmarks/bench/reduce/warp_reduce_base.cuh`
- `cub/benchmarks/bench/reduce/warp_reduce_min.cu`
- `cub/benchmarks/bench/reduce/warp_reduce_sum.cu`
- `cub/cub/warp/specializations/warp_reduce_shfl.cuh`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-6819`
