From c8bc5377ac59c6e6af5c0e925fa0af7d9df7ebc0 Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Mon, 4 Nov 2013 11:08:10 +0100
Subject: [PATCH] Issue #16286: write a new subfunction bytes_compare_eq()

* cleanup bytes_richcompare()
* PyUnicode_RichCompare(): replace a test with a XOR
---
 Objects/bytesobject.c   | 84 +++++++++++++++++++++++------------------
 Objects/unicodeobject.c |  8 ++--
 2 files changed, 50 insertions(+), 42 deletions(-)

diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 529c634708c..9aa3ee286b1 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -802,6 +802,23 @@ bytes_item(PyBytesObject *a, Py_ssize_t i)
     return PyLong_FromLong((unsigned char)a->ob_sval[i]);
 }
 
+Py_LOCAL(int)
+bytes_compare_eq(PyBytesObject *a, PyBytesObject *b)
+{
+    int cmp;
+    Py_ssize_t len;
+
+    len = Py_SIZE(a);
+    if (Py_SIZE(b) != len)
+        return 0;
+
+    if (a->ob_sval[0] != b->ob_sval[0])
+        return 0;
+
+    cmp = memcmp(a->ob_sval, b->ob_sval, len);
+    return (cmp == 0);
+}
+
 static PyObject*
 bytes_richcompare(PyBytesObject *a, PyBytesObject *b, int op)
 {
@@ -822,53 +839,46 @@ bytes_richcompare(PyBytesObject *a, PyBytesObject *b, int op)
                 return NULL;
         }
         result = Py_NotImplemented;
-        goto out;
     }
-    if (a == b) {
+    else if (a == b) {
         switch (op) {
         case Py_EQ:case Py_LE:case Py_GE:
             result = Py_True;
-            goto out;
+            break;
         case Py_NE:case Py_LT:case Py_GT:
             result = Py_False;
-            goto out;
+            break;
         }
     }
-    if (op == Py_EQ) {
-        /* Supporting Py_NE here as well does not save
-           much time, since Py_NE is rarely used.  */
-        if (Py_SIZE(a) == Py_SIZE(b)
-            && (a->ob_sval[0] == b->ob_sval[0]
-            && memcmp(a->ob_sval, b->ob_sval, Py_SIZE(a)) == 0)) {
-            result = Py_True;
-        } else {
-            result = Py_False;
+    else if (op == Py_EQ || op == Py_NE) {
+        int eq = bytes_compare_eq(a, b);
+        eq ^= (op == Py_NE);
+        result = eq ? Py_True : Py_False;
+    }
+    else {
+        len_a = Py_SIZE(a); len_b = Py_SIZE(b);
+        min_len = (len_a < len_b) ? len_a : len_b;
+        if (min_len > 0) {
+            c = Py_CHARMASK(*a->ob_sval) - Py_CHARMASK(*b->ob_sval);
+            if (c==0)
+                c = memcmp(a->ob_sval, b->ob_sval, min_len);
         }
-        goto out;
+        else
+            c = 0;
+        if (c == 0)
+            c = (len_a < len_b) ? -1 : (len_a > len_b) ? 1 : 0;
+        switch (op) {
+        case Py_LT: c = c <  0; break;
+        case Py_LE: c = c <= 0; break;
+        case Py_GT: c = c >  0; break;
+        case Py_GE: c = c >= 0; break;
+        default:
+            assert(op != Py_EQ && op != Py_NE);
+            Py_RETURN_NOTIMPLEMENTED;
+        }
+        result = c ? Py_True : Py_False;
     }
-    len_a = Py_SIZE(a); len_b = Py_SIZE(b);
-    min_len = (len_a < len_b) ? len_a : len_b;
-    if (min_len > 0) {
-        c = Py_CHARMASK(*a->ob_sval) - Py_CHARMASK(*b->ob_sval);
-        if (c==0)
-            c = memcmp(a->ob_sval, b->ob_sval, min_len);
-    } else
-        c = 0;
-    if (c == 0)
-        c = (len_a < len_b) ? -1 : (len_a > len_b) ? 1 : 0;
-    switch (op) {
-    case Py_LT: c = c <  0; break;
-    case Py_LE: c = c <= 0; break;
-    case Py_EQ: assert(0);  break; /* unreachable */
-    case Py_NE: c = c != 0; break;
-    case Py_GT: c = c >  0; break;
-    case Py_GE: c = c >= 0; break;
-    default:
-        result = Py_NotImplemented;
-        goto out;
-    }
-    result = c ? Py_True : Py_False;
-  out:
+
     Py_INCREF(result);
     return result;
 }
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 01e5355449f..17ae481aec9 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -10526,7 +10526,7 @@ unicode_compare(PyObject *str1, PyObject *str2)
 #undef COMPARE
 }
 
-static int
+Py_LOCAL(int)
 unicode_compare_eq(PyObject *str1, PyObject *str2)
 {
     int kind;
@@ -10630,10 +10630,8 @@ PyUnicode_RichCompare(PyObject *left, PyObject *right, int op)
 
     if (op == Py_EQ || op == Py_NE) {
         result = unicode_compare_eq(left, right);
-        if (op == Py_EQ)
-            v = TEST_COND(result);
-        else
-            v = TEST_COND(!result);
+        result ^= (op == Py_NE);
+        v = TEST_COND(result);
     }
     else {
         result = unicode_compare(left, right);