[Python-checkins] cpython: Optimize unicode_compare(): use memcmp() when comparing two UCS1 strings

[victor.stinner]

http://hg.python.org/cpython/rev/54154be6b27d
changeset:   79469:54154be6b27d
user:        Victor Stinner <victor.stinner at gmail.com>
date:        Thu Oct 04 22:59:45 2012 +0200
summary:
  Optimize unicode_compare(): use memcmp() when comparing two UCS1 strings

files:
  Objects/unicodeobject.c |  41 ++++++++++++++++++++--------
  1 files changed, 29 insertions(+), 12 deletions(-)


diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -10443,7 +10443,8 @@
 {
     int kind1, kind2;
     void *data1, *data2;
-    Py_ssize_t len1, len2, i;
+    Py_ssize_t len1, len2;
+    Py_ssize_t i, len;
 
     /* a string is equal to itself */
     if (str1 == str2)
@@ -10455,17 +10456,33 @@
     data2 = PyUnicode_DATA(str2);
     len1 = PyUnicode_GET_LENGTH(str1);
     len2 = PyUnicode_GET_LENGTH(str2);
-
-    for (i = 0; i < len1 && i < len2; ++i) {
-        Py_UCS4 c1, c2;
-        c1 = PyUnicode_READ(kind1, data1, i);
-        c2 = PyUnicode_READ(kind2, data2, i);
-
-        if (c1 != c2)
-            return (c1 < c2) ? -1 : 1;
-    }
-
-    return (len1 < len2) ? -1 : (len1 != len2);
+    len = Py_MIN(len1, len2);
+
+    if (kind1 == 1 && kind2 == 1) {
+        int cmp = memcmp(data1, data2, len);
+        /* normalize result of memcmp() into the range [-1; 1] */
+        if (cmp < 0)
+            return -1;
+        if (cmp > 0)
+            return 1;
+    }
+    else {
+        for (i = 0; i < len; ++i) {
+            Py_UCS4 c1, c2;
+            c1 = PyUnicode_READ(kind1, data1, i);
+            c2 = PyUnicode_READ(kind2, data2, i);
+
+            if (c1 != c2)
+                return (c1 < c2) ? -1 : 1;
+        }
+    }
+
+    if (len1 == len2)
+        return 0;
+    if (len1 < len2)
+        return -1;
+    else
+        return 1;
 }
 
 int

-- 
Repository URL: http://hg.python.org/cpython