Messages in this thread | | | Date | Sat, 2 Sep 2023 13:11:06 +0700 | From | Ammar Faizi <> | Subject | Re: [RFC PATCH v2 1/4] tools/nolibc: x86-64: Use `rep movsb` for `memcpy()` and `memmove()` |
| |
On Sat, Sep 02, 2023 at 01:07:50PM +0700, Alviro Iskandar Setiawan wrote: > Btw, sir, this can be simplified more by merging the forward copy > path, only using two "rep movsb" for both memmove() and memcpy() > should be enough? > ``` > __asm__ ( > ".section .text.nolibc_memmove_memcpy\n" > ".weak memmove\n" > ".weak memcpy\n" > "memmove:\n" > "movq %rdx, %rcx\n" > "movq %rdi, %rdx\n" > "movq %rdi, %rax\n" > "subq %rsi, %rdx\n" > "cmpq %rcx, %rdx\n" > "jnb __nolibc_forward_copy\n" > "leaq -1(%rdi, %rcx, 1), %rdi\n" > "leaq -1(%rsi, %rcx, 1), %rsi\n" > "std\n" > "rep movsb\n" > "cld\n" > "retq\n" > > "memcpy:\n" > "movq %rdi, %rax\n" > "movq %rdx, %rcx\n" > "__nolibc_forward_copy:\n" > "rep movsb\n" > "retq\n" > ); > ```
Looks good. I'll apply that change.
-- Ammar Faizi
| |