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libc: optimize memmove() with memcpy() if possible.

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Change-Id: I90e578fdc82e427caee8fa4157ce3f8c6c99926d
This commit is contained in:
David 'Digit' Turner 2010-10-07 11:03:32 +02:00
parent af00228b70
commit 5b81b91817
1 changed files with 4 additions and 1 deletions
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5
libc/string/memmove.c
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@ -31,7 +31,10 @@ void *memmove(void *dst, const void *src, size_t n)
{ {
const char *p = src; const char *p = src;
char *q = dst; 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); return memcpy(dst, src, n);
} else { } else {
#define PRELOAD_DISTANCE 64 #define PRELOAD_DISTANCE 64