Merge "libc: memmove(): non-overlapping block optim." into gingerbread

79260746 · David 'Digit' Turner · Android (Google) Code Review · 032a7135 · 80fba9a2 · 79260746
Commit 79260746 authored 14 years ago by David 'Digit' Turner Committed by Android (Google) Code Review 14 years ago
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libc/string/memmove.c libc/string/memmove.c +5 -1

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--- a/libc/string/memmove.c
+++ b/libc/string/memmove.c
@@ -31,7 +31,11 @@ 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 highgly-optimized memcpy() if the destination
+   * is before the source, or if the two blocks are non-overlapping
+   */
+  if (__builtin_expect((q < p || (q-p) <= (ptrdiff_t)n), 1)) {
    return memcpy(dst, src, n);
  } else {
 #define PRELOAD_DISTANCE 64