---
id: pr-cccl-cub-8107
repo: NVIDIA/cccl
pr: 8107
title: Implement parallel `cuda::std::shift_left`
author: miscco
date: '2026-04-20'
url: https://github.com/NVIDIA/cccl/pull/8107
source_category: upstream-code
architectures:
- sm100
tags:
- blackwell
techniques: []
hardware_features:
- blackwell
kernel_types: []
languages:
- cuda-cpp
captured_at: '2026-05-16'
status: merged
merge_sha: a7acb9181b378cdc7cae60ff9c1d286962b8cb47
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- cub/cub/device/device_select.cuh
- libcudacxx/benchmarks/bench/shift_left/basic.cu
- libcudacxx/benchmarks/bench/shift_right/basic.cu
- libcudacxx/include/cuda/std/__pstl/cuda/shift_left.h
- libcudacxx/include/cuda/std/__pstl/cuda/shift_right.h
- libcudacxx/include/cuda/std/__pstl/dispatch.h
- libcudacxx/include/cuda/std/__pstl/shift_left.h
- libcudacxx/include/cuda/std/__pstl/shift_right.h
- libcudacxx/include/cuda/std/execution
- libcudacxx/test/libcudacxx/std/algorithms/alg.modifying/alg.shift/pstl_shift_left.cu
- libcudacxx/test/libcudacxx/std/algorithms/alg.modifying/alg.shift/pstl_shift_right.cu
artifact_dir: evidence/pull-bundles/cccl-cub/gh-8107
head_ref_oid: 5447cc216c49837acd89b7749615db0a694a783d
---
# Implement parallel `cuda::std::shift_left`

- Repository: `NVIDIA/cccl`
- PR: [8107](https://github.com/NVIDIA/cccl/pull/8107)
- 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_select.cuh`
- `libcudacxx/benchmarks/bench/shift_left/basic.cu`
- `libcudacxx/benchmarks/bench/shift_right/basic.cu`
- `libcudacxx/include/cuda/std/__pstl/cuda/shift_left.h`
- `libcudacxx/include/cuda/std/__pstl/cuda/shift_right.h`
- `libcudacxx/include/cuda/std/__pstl/dispatch.h`
- `libcudacxx/include/cuda/std/__pstl/shift_left.h`
- `libcudacxx/include/cuda/std/__pstl/shift_right.h`
- `libcudacxx/include/cuda/std/execution`
- `libcudacxx/test/libcudacxx/std/algorithms/alg.modifying/alg.shift/pstl_shift_left.cu`
- `libcudacxx/test/libcudacxx/std/algorithms/alg.modifying/alg.shift/pstl_shift_right.cu`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-8107`
