+ const char *haystack = haystack_start;
+ const char *needle = needle_start;
+ size_t needle_len; /* Length of NEEDLE. */
+ size_t haystack_len; /* Known minimum length of HAYSTACK. */
+ bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
+
+ /* Determine length of NEEDLE, and in the process, make sure
+ HAYSTACK is at least as long (no point processing all of a long
+ NEEDLE if HAYSTACK is too short). */
+ while (*haystack && *needle)
+ ok &= *haystack++ == *needle++;
+ if (*needle)
+ return NULL;
+ if (ok)
+ return (char *) haystack_start;
+
+ /* Reduce the size of haystack using strchr, since it has a smaller
+ linear coefficient than the Two-Way algorithm. */
+ needle_len = needle - needle_start;
+ haystack = strchr (haystack_start + 1, *needle_start);
+ if (!haystack || __builtin_expect (needle_len == 1, 0))
+ return (char *) haystack;
+ needle -= needle_len;
+ haystack_len = (haystack > haystack_start + needle_len ? 1
+ : needle_len + haystack_start - haystack);
+
+ /* Perform the search. Abstract memory is considered to be an array
+ of 'unsigned char' values, not an array of 'char' values. See
+ ISO C 99 section 6.2.6.1. */
+ if (needle_len < LONG_NEEDLE_THRESHOLD)
+ return two_way_short_needle ((const unsigned char *) haystack,
+ haystack_len,
+ (const unsigned char *) needle, needle_len);
+ return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
+ (const unsigned char *) needle, needle_len);