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| author | David 'Digit' Turner <digit@google.com> | 2010-10-07 11:03:32 +0200 |
|---|---|---|
| committer | David 'Digit' Turner <digit@google.com> | 2010-10-07 11:03:32 +0200 |
| commit | 5b81b918173b4bf446c1a85240c094e4dd77231f (patch) | |
| tree | dd4cab2ff2183ab7a13833f343870d57baaa1250 | |
| parent | af00228b705b53165c132a22b30c2d6cbb9acd13 (diff) | |
| download | bionic-5b81b918173b4bf446c1a85240c094e4dd77231f.zip bionic-5b81b918173b4bf446c1a85240c094e4dd77231f.tar.gz bionic-5b81b918173b4bf446c1a85240c094e4dd77231f.tar.bz2 | |
libc: optimize memmove() with memcpy() if possible.
Change-Id: I90e578fdc82e427caee8fa4157ce3f8c6c99926d
| -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 |