# [PATCH] compat/bswap.h: don't assume MSVC is little-endian 3 messages from 2020-11-11 to 2020-11-11. Participants: Daniel Gurney, Johannes Schindelin, Junio C Hamano. Thread: https://gitlist.dev/t/54618 ## Daniel Gurney, 2020-11-11 08:32 Subject: [PATCH] compat/bswap.h: don't assume MSVC is little-endian Message-ID: <20201111083227.605518-1-dgurney99@gmail.com> URL: https://gitlist.dev/e/20201111083227.605518-1-dgurney99%40gmail.com ``` In 1af265f0 (compat/bswap.h: simplify MSVC endianness detection, 2020-11-08) we attempted to simplify code by assuming MSVC builds will be for little-endian machines, since only unusably old versions of MSVC supported big-endian MIPS and m68k architectures. However, it's possible that MSVC could be ported to build for a big-endian architecture again, so the simplification wasn't as future-proof as hoped. So let's go back to the old way of detecting MSVC, and then checking architecture from a list of little-endian architecture macros. Note that MSVC does not treat ARM64 as bi-endian, so we can safely treat it as little-endian. Helped-by: brian m. carlson Helped-by: Jeff King Helped-by: Johannes Schindelin Helped-by: Junio C Hamano Signed-off-by: Daniel Gurney --- compat/bswap.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/compat/bswap.h b/compat/bswap.h index 72f225eaa8..512f6f4b99 100644 --- a/compat/bswap.h +++ b/compat/bswap.h @@ -74,7 +74,7 @@ static inline uint64_t git_bswap64(uint64_t x) } #endif -#elif defined(_MSC_VER) +#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64) || defined(_M_ARM64)) #include -- 2.29.2 ``` ## Johannes Schindelin, 2020-11-11 16:23 Subject: Re: [PATCH] compat/bswap.h: don't assume MSVC is little-endian Message-ID: URL: https://gitlist.dev/e/nycvar.QRO.7.76.6.2011111723050.18437%40tvgsbejvaqbjf.bet In-Reply-To: <20201111083227.605518-1-dgurney99@gmail.com> ``` Hi Daniel, On Wed, 11 Nov 2020, Daniel Gurney wrote: > In 1af265f0 (compat/bswap.h: simplify MSVC endianness > detection, 2020-11-08) we attempted to simplify code by assuming MSVC > builds will be for little-endian machines, since only unusably old > versions of MSVC supported big-endian MIPS and m68k architectures. > > However, it's possible that MSVC could be ported to build for a > big-endian architecture again, so the simplification wasn't as > future-proof as hoped. > > So let's go back to the old way of detecting MSVC, and then checking > architecture from a list of little-endian architecture macros. > > Note that MSVC does not treat ARM64 as bi-endian, so we can safely treat > it as little-endian. > > Helped-by: brian m. carlson > Helped-by: Jeff King > Helped-by: Johannes Schindelin > Helped-by: Junio C Hamano > Signed-off-by: Daniel Gurney ACK! Thank you so much, Dscho > --- > compat/bswap.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/compat/bswap.h b/compat/bswap.h > index 72f225eaa8..512f6f4b99 100644 > --- a/compat/bswap.h > +++ b/compat/bswap.h > @@ -74,7 +74,7 @@ static inline uint64_t git_bswap64(uint64_t x) > } > #endif > > -#elif defined(_MSC_VER) > +#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64) || defined(_M_ARM64)) > > #include > > -- > 2.29.2 > > ``` ## Junio C Hamano, 2020-11-11 16:40 Subject: Re: [PATCH] compat/bswap.h: don't assume MSVC is little-endian Message-ID: URL: https://gitlist.dev/e/xmqqo8k34zko.fsf%40gitster.c.googlers.com In-Reply-To: ``` Johannes Schindelin writes: >> ... >> So let's go back to the old way of detecting MSVC, and then checking >> architecture from a list of little-endian architecture macros. >> >> Note that MSVC does not treat ARM64 as bi-endian, so we can safely treat >> it as little-endian. >> >> Helped-by: brian m. carlson >> Helped-by: Jeff King >> Helped-by: Johannes Schindelin >> Helped-by: Junio C Hamano >> Signed-off-by: Daniel Gurney > > ACK! > > Thank you so much, > Dscho Thanks, all. ```