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libbb/bitops.c: add inlining comment

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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Denys Vlasenko 2025-07-09 08:21:47 +02:00
parent c305c81c94
commit 11d4c08d75
1 changed files with 20 additions and 0 deletions
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libbb/bitops.c
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@ -58,6 +58,26 @@ void FAST_FUNC xorbuf16_aligned_long(void *dst, const void *src)
# endif
#endif
}
// The above can be inlined in libbb.h, in a way where compiler
// is even free to use better addressing modes than (%reg), and
// to keep the result in a register
// (to not store it to memory after each XOR):
//#if defined(__SSE__)
//#include <xmmintrin.h>
//^^^ or just: typedef float __m128_u attribute((__vector_size__(16),__may_alias__,__aligned__(1)));
//static ALWAYS_INLINE void xorbuf16_aligned_long(void *dst, const void *src)
//{
// __m128_u xmm0, xmm1;
// asm volatile(
//"\n xorps %1,%0"
// : "=x" (xmm0), "=x" (xmm1)
// : "0" (*(__m128_u*)dst), "1" (*(__m128_u*)src)
// );
// *(__m128_u*)dst = xmm0; // this store may be optimized out!
//}
//#endif
// but I don't trust gcc optimizer enough to not generate some monstrosity.
// See GMULT() function in TLS code as an example.
void FAST_FUNC xorbuf64_3_aligned64(void *dst, const void *src1, const void *src2)
{