[PATCH 2/2] bswap: add NO_UNALIGNED_LOADS define
- From
Jeff King <peff@peff.net>
- Date
- Dec 29, 2015, 06:36 UTC
- Message-ID
- <20151229063600.GB30340@sigill.intra.peff.net>
- In-Reply-To
- <20151229063449.GA28755@sigill.intra.peff.net>
The byte-swapping code automatically decides, based on the platform, whether it is sensible to cast an do a potentially unaligned ntohl(), or to pick individual bytes out of an array.
It can be handy to override this decision, though, when turning on compiler flags that will complain about unaligned loads (such as -fsanitize=undefined). This patch adds a macro check to make this possible.
There's no nice Makefile knob here; this is for prodding at Git's internals, and anybody using it can set "-DNO_UNALIGNED_LOADS" in the same place they are setting up "-fsanitize".
Signed-off-by: Jeff King <peff@peff.net> --- compat/bswap.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/compat/bswap.h b/compat/bswap.h index 7fed637..d47c003 100644 --- a/compat/bswap.h +++ b/compat/bswap.h @@ -149,11 +149,12 @@ static inline uint64_t git_bswap64(uint64_t x) * and is faster on architectures with memory alignment issues. */ -#if defined(__i386__) || defined(__x86_64__) || \ +#if !defined(NO_UNALIGNED_LOADS) && ( \ + defined(__i386__) || defined(__x86_64__) || \ defined(_M_IX86) || defined(_M_X64) || \ defined(__ppc__) || defined(__ppc64__) || \ defined(__powerpc__) || defined(__powerpc64__) || \ - defined(__s390__) || defined(__s390x__) + defined(__s390__) || defined(__s390x__)) #define get_be16(p) ntohs(*(unsigned short *)(p)) #define get_be32(p) ntohl(*(unsigned int *)(p))
-- 2.7.0.rc2.368.g1cbb535