github.com/afumu/libc@v0.0.6/musl/src/string/x86_64/memmove.s (about)

     1  .global memmove
     2  .type memmove,@function
     3  memmove:
     4  	mov %rdi,%rax
     5  	sub %rsi,%rax
     6  	cmp %rdx,%rax
     7  .hidden __memcpy_fwd
     8  	jae __memcpy_fwd
     9  	mov %rdx,%rcx
    10  	lea -1(%rdi,%rdx),%rdi
    11  	lea -1(%rsi,%rdx),%rsi
    12  	std
    13  	rep movsb
    14  	cld
    15  	lea 1(%rdi),%rax
    16  	ret