Update strcmp implementation, to improve performance

JerryScript-DCO-1.0-Signed-off-by: Xin Hu [email protected]

Author: huxinx

jerry-libc/jerry-libc.c

@@ -156,43 +156,23 @@ CALL_PRAGMA (GCC diagnostic pop)
 /** Compare two strings. return an integer less than, equal to, or greater than zero
      if s1 is found, respectively, to be less than, to match, or be greater than s2.  */
 int
-strcmp (const char *s1, const char *s2)
+strcmp (const char *str1, const char *str2)
 {
-  size_t i;
-  if (s1 == NULL)
-  {
-    if (s2 != NULL)
-    {
-      return -1;
-    }
-    else
-    {
-      return 0;
-    }
-  }
-  if (s2 == NULL)
+  int s1;
+  int s2;
+  do
   {
-    return 1;
-  }
+    s1 = *str1++;
+    s2 = *str2++;
 
-  for (i = 0; s1[i]; i++)
-  {
-    if (s1[i] > s2[i])
-    {
-      return 1;
-    }
-    else if (s1[i] < s2[i])
+    if (s1 == 0)
     {
-      return -1;
+      break;
     }
   }
+  while (s1 == s2);
 
-  if (s2[i])
-  {
-    return -1;
-  }
-
-  return 0;
+  return (s1 < s2) ? -1 : (s1 > s2 ? 1 : 0);
 }
 
 /** Compare two strings. return an integer less than, equal to, or greater than zero