alt Hacker NewsX86-64 has the REP prefix for string operation. When combined with the MOVS instruction, that is pretty much an instruction for strcpy.
X86-64 has the REP prefix for string operation. When combined with the MOVS instruction, that is pretty much an instruction for strcpy.
No, it's an instruction for memcpy. You still need to compute the string length first, which means touching every byte individually because you can't use SIMD due to alignment assumptions (or lack thereof) and the potential to touch uninitialized or unmapped memory (when the string crosses a page boundary).