Comment 230 for bug 727064

Here, this one actually has a chance of working, still, totally untested.

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cat > $HOME/Downloads/linusmemcpy.c <<EOF
#include <sys/types.h>

void *memcpy(void *dst, const void *src, size_t size)
{
void *orig = dst;
#if __WORDSIZE == 64
asm volatile("rep ; movsq" :"=D" (dst), "=S" (src)
: "0" (dst), "1" (src), "c" (size >> 3) : "memory");
asm volatile("rep ; movsb" : "=D" (dst), "=S" (src)
: "0" (dst), "1" (src), "c" (size & 7) : "memory");
#else
asm volatile("rep ; movsl" :"=D" (dst), "=S" (src)
: "0" (dst), "1" (src), "c" (size >> 2) : "memory");
asm volatile("rep ; movsb" : "=D" (dst), "=S" (src)
: "0" (dst), "1" (src), "c" (size & 3) : "memory");
#endif
return orig;
}
EOF
cd $HOME/Downloads
gcc -O2 -c linusmemcpy.c
ld -G linusmemcpy.o -o linusmemcpy.so
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