From: Rich Felker Date: Mon, 10 Sep 2012 22:16:11 +0000 (-0400) Subject: reenable word-at-at-time copying in memmove X-Git-Tag: v0.9.5~14 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=1701e4f3d46b14c4c4be8a46e64f8eaf15a5c061;p=oweals%2Fmusl.git reenable word-at-at-time copying in memmove before restrict was added, memove called memcpy for forward copies and used a byte-at-a-time loop for reverse copies. this was changed to avoid invoking UB now that memcpy has an undefined copying order, making memmove considerably slower. performance is still rather bad, so I'll be adding asm soon. --- diff --git a/src/string/memmove.c b/src/string/memmove.c index 9153a644..27f670e1 100644 --- a/src/string/memmove.c +++ b/src/string/memmove.c @@ -1,13 +1,36 @@ #include +#include + +#define WT size_t +#define WS (sizeof(WT)) void *memmove(void *dest, const void *src, size_t n) { char *d = dest; const char *s = src; + if (d==s) return d; - if ((size_t)(d-s) < n) - while (n--) d[n] = s[n]; - else - while (n--) *d++ = *s++; + if (s+n <= d || d+n <= s) return memcpy(d, s, n); + + if (d=WS; n-=WS, d+=WS, s+=WS) *(WT *)d = *(WT *)s; + } + for (; n; n--) *d++ = *s++; + } else { + if ((uintptr_t)s % WS == (uintptr_t)d % WS) { + while ((uintptr_t)(d+n) % WS) { + if (!n--) return dest; + d[n] = s[n]; + } + while (n>=WS) n-=WS, *(WT *)(d+n) = *(WT *)(s+n); + } + while (n) n--, d[n] = s[n]; + } + return dest; }