Memchr() speed-up for unanchored pattern in 8-bit mode.

ChangeLog

@@ -6,6 +6,9 @@ Version 10.21 xx-xxx-xxxx
 
 1. Improve matching speed of patterns starting with + or * in JIT.
 
+2. Use memchr() to find the first character in an unanchored match in 8-bit
+mode in the interpreter. This gives a significant speed improvement.
+
 
 Version 10.20 30-June-2015
 --------------------------

configure.ac

@@ -9,9 +9,9 @@ dnl The PCRE2_PRERELEASE feature is for identifying release candidates. It might
 dnl be defined as -RC2, for example. For real releases, it should be empty.
 
 m4_define(pcre2_major, [10])
-m4_define(pcre2_minor, [20])
-m4_define(pcre2_prerelease, [])
-m4_define(pcre2_date, [2015-06-30])
+m4_define(pcre2_minor, [21])
+m4_define(pcre2_prerelease, [-RC1])
+m4_define(pcre2_date, [2015-07-06])
 
 # NOTE: The CMakeLists.txt file searches for the above variables in the first
 # 50 lines of this file. Please update that if the variables above are moved.

src/pcre2_match.c

@@ -6783,7 +6783,8 @@ for(;;)
       end_subject = t;
       }
 
-    /* Advance to a unique first code unit if there is one. */
+    /* Advance to a unique first code unit if there is one. In 8-bit mode, the 
+    use of memchr() gives a big speed up. */
 
     if (has_first_cu)
       {
@@ -6793,8 +6794,15 @@ for(;;)
           (smc = UCHAR21TEST(start_match)) != first_cu && smc != first_cu2)
           start_match++;
       else
+        {
+#if PCRE2_CODE_UNIT_WIDTH != 8
         while (start_match < end_subject && UCHAR21TEST(start_match) != first_cu)
           start_match++;
+#else
+        start_match = memchr(start_match, first_cu, end_subject - start_match);
+        if (start_match == NULL) start_match = end_subject;
+#endif          
+        }   
       }
 
     /* Or to just after a linebreak for a multiline match */