diff options
| -rw-r--r-- | libc/string/memmove.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/libc/string/memmove.c b/libc/string/memmove.c index fcaf4ee..98ecfc9 100644 --- a/libc/string/memmove.c +++ b/libc/string/memmove.c @@ -31,7 +31,10 @@ void *memmove(void *dst, const void *src, size_t n) { const char *p = src; char *q = dst; - if (__builtin_expect(q < p, 1)) { + /* We can use the optimized memcpy if the destination is below the + * source (i.e. q < p), or if it is completely over it (i.e. q >= p+n). + */ + if (__builtin_expect((q < p) || ((size_t)(q - p) >= n), 1)) { return memcpy(dst, src, n); } else { #define PRELOAD_DISTANCE 64 |