optimise str == unicode / unicode == str in Py2

Cython/Utility/StringTools.c

@@ -138,10 +138,32 @@ static CYTHON_INLINE int __Pyx_PyUnicode_Equals(PyObject* s1, PyObject* s2, int
 #if CYTHON_COMPILING_IN_PYPY
     return PyObject_RichCompareBool(s1, s2, equals);
 #else
+#if PY_MAJOR_VERSION < 3
+    PyObject* owned_ref = NULL;
+#endif
+    int s1_is_unicode, s2_is_unicode;
     if (s1 == s2) {
         /* as done by PyObject_RichCompareBool(); also catches the (interned) empty string */
-        return (equals == Py_EQ);
-    } else if (PyUnicode_CheckExact(s1) & PyUnicode_CheckExact(s2)) {
+        goto return_eq;
+    }
+    s1_is_unicode = PyUnicode_CheckExact(s1);
+    s2_is_unicode = PyUnicode_CheckExact(s2);
+#if PY_MAJOR_VERSION < 3
+    if ((s1_is_unicode & (!s2_is_unicode)) && PyString_CheckExact(s2)) {
+        owned_ref = PyUnicode_FromObject(s2);
+        if (unlikely(!owned_ref))
+            return -1;
+        s2 = owned_ref;
+        s2_is_unicode = 1;
+    } else if ((s2_is_unicode & (!s1_is_unicode)) && PyString_CheckExact(s1)) {
+        owned_ref = PyUnicode_FromObject(s1);
+        if (unlikely(!owned_ref))
+            return -1;
+        s1 = owned_ref;
+        s1_is_unicode = 1;
+    }
+#endif
+    if (s1_is_unicode & s2_is_unicode) {
         Py_ssize_t length;
         int kind;
         void *data1, *data2;
@@ -150,26 +172,31 @@ static CYTHON_INLINE int __Pyx_PyUnicode_Equals(PyObject* s1, PyObject* s2, int
             return -1;
         #endif
         length = __Pyx_PyUnicode_GET_LENGTH(s1);
-        if (length != __Pyx_PyUnicode_GET_LENGTH(s2))
-            return (equals == Py_NE);
+        if (length != __Pyx_PyUnicode_GET_LENGTH(s2)) {
+            goto return_ne;
+        }
         // len(s1) == len(s2) >= 1  (empty string is interned, and "s1 is not s2")
         kind = __Pyx_PyUnicode_KIND(s1);
-        if (kind != __Pyx_PyUnicode_KIND(s2))
-            return (equals == Py_NE);
+        if (kind != __Pyx_PyUnicode_KIND(s2)) {
+            goto return_ne;
+        }
         data1 = __Pyx_PyUnicode_DATA(s1);
         data2 = __Pyx_PyUnicode_DATA(s2);
         if (__Pyx_PyUnicode_READ(kind, data1, 0) != __Pyx_PyUnicode_READ(kind, data2, 0)) {
-            return (equals == Py_NE);
+            goto return_ne;
         } else if (length == 1) {
-            return (equals == Py_EQ);
+            goto return_eq;
         } else {
             int result = memcmp(data1, data2, length * kind);
+            #if PY_MAJOR_VERSION < 3
+            Py_XDECREF(owned_ref);
+            #endif
             return (equals == Py_EQ) ? (result == 0) : (result != 0);
         }
-    } else if ((s1 == Py_None) & PyUnicode_CheckExact(s2)) {
-        return (equals == Py_NE);
-    } else if ((s2 == Py_None) & PyUnicode_CheckExact(s1)) {
-        return (equals == Py_NE);
+    } else if ((s1 == Py_None) & s2_is_unicode) {
+        goto return_ne;
+    } else if ((s2 == Py_None) & s1_is_unicode) {
+        goto return_ne;
     } else {
         int result;
         PyObject* py_result = PyObject_RichCompare(s1, s2, equals);
@@ -179,6 +206,16 @@ static CYTHON_INLINE int __Pyx_PyUnicode_Equals(PyObject* s1, PyObject* s2, int
         Py_DECREF(py_result);
         return result;
     }
+return_eq:
+    #if PY_MAJOR_VERSION < 3
+    Py_XDECREF(owned_ref);
+    #endif
+    return (equals == Py_EQ);
+return_ne:
+    #if PY_MAJOR_VERSION < 3
+    Py_XDECREF(owned_ref);
+    #endif
+    return (equals == Py_NE);
 #endif
 }