http://bugs.python.org/issue2459 -- speed up loops

Objects/codeobject.c

 #include "Python.h"
 #include "code.h"
 #include "structmember.h"
 
 #define NAME_CHARS \
         "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz"
 
 /* all_name_chars(s): true iff all chars in s are valid NAME_CHARS */
 
 static int
@@ skipping 611 matching lines @@
            the line increments here, treating them as byte
            increments gets confusing, to say the least. */
 
         bounds->ap_lower = 0;
         while (size > 0) {
                 if (addr + *p > lasti)
                         break;
                 addr += *p++;
                 if (*p) 
                         bounds->ap_lower = addr;
-                line += *p++;
+                line += (signed char) *p++;
                 --size;
         }
 
         /* If lasti and addr don't match exactly, we don't want to
            change the lineno slot on the frame or execute a trace
            function.  Return -1 instead.
         */
         if (addr != lasti)
                 line = -1;
         
         if (size > 0) {
                 while (--size >= 0) {
                         addr += *p++;
                         if (*p++)
                                 break;
                 }
                 bounds->ap_upper = addr;
         }
         else {
                 bounds->ap_upper = INT_MAX;
         }
 
         return line;
 }