bswap.h: add support for built-in bswap functions

Newer compiler versions, like GCC 10 and Clang 12, have built-in
functions for bswap32 and bswap64. This comes in handy, for example,
when targeting CLANGARM64 on Windows, which would not be supported
without this logic.

Signed-off-by: Dennis Ameling <dennis@dennisameling.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Dennis Ameling
2025-04-23 08:01:43 +00:00
committed by Junio C Hamano
parent 683c54c999
commit 6547d1c9cb

View File

@@ -35,7 +35,19 @@ static inline uint64_t default_bswap64(uint64_t val)
#undef bswap32 #undef bswap32
#undef bswap64 #undef bswap64
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)) /**
* __has_builtin is available since Clang 10 and GCC 10.
* Below is a fallback for older compilers.
*/
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif
#if __has_builtin(__builtin_bswap32) && __has_builtin(__builtin_bswap64)
#define bswap32(x) __builtin_bswap32((x))
#define bswap64(x) __builtin_bswap64((x))
#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
#define bswap32 git_bswap32 #define bswap32 git_bswap32
static inline uint32_t git_bswap32(uint32_t x) static inline uint32_t git_bswap32(uint32_t x)