Landing: 9ab08d664545

← All landings

Project / Subsystem

gcc / gcc

Date

2026-06-05

Author

Jakub Jelinek

Commit

9ab08d664545bcea9164040e806385369fdaaf0e

Source

github

Perf win

Breaking

View on GitHub →

All attributes

project: gcc
subsystem: gcc
patch_id: —
commit_hash: 9ab08d664545bcea9164040e806385369fdaaf0e
source_type: github
headline: C and C++ now support `__builtin_bswapg` and `__builtin_bitreverseg` for generic types
tldr: GCC now provides type-generic built-in functions `__builtin_bswapg` and `__builtin_bitreverseg` for byte-swapping and bit-reversal, similar to Clang's offering…
author: Jakub Jelinek
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • c
• c++
• builtins
• type-generic
• bit-manipulation
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/9ab08d664545bcea9164040e806385369fdaaf0e
date: 2026-06-05T00:00:00.000Z

GCC now introduces __builtin_bswapg and __builtin_bitreverseg, new type-generic built-in functions for byte-swapping and bit-reversal operations, respectively. These built-ins address PR c/122731 and align GCC’s functionality with Clang’s, promoting better cross-compiler compatibility. Unlike other type-generic built-ins, these return the same type as their argument and specifically require unsigned integer or _BitInt types with precision divisible by 8 for __builtin_bswapg.