From b8b5f0bf4b546358239876f1b38553efdbce7ed6 Mon Sep 17 00:00:00 2001
From: hongweipeng <961365124@qq.com>
Date: Sun, 15 Sep 2019 01:32:28 +0800
Subject: [PATCH 1/6] improve perfomance of long_compare

---
 .../2019-09-15-01-30-06.bpo-35696.1iK_1H.rst       |  1 +
 Objects/longobject.c                               | 14 +++++---------
 2 files changed, 6 insertions(+), 9 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst b/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst
new file mode 100644
index 00000000000000..729824cc3a4601
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst	
@@ -0,0 +1 @@
+Slightly improve perfomance of long_compare. Patch by hongweipeng.
diff --git a/Objects/longobject.c b/Objects/longobject.c
index 5da6951b258948..02546d913daf70 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3038,17 +3038,13 @@ long_compare(PyLongObject *a, PyLongObject *b)
     }
     else {
         Py_ssize_t i = Py_ABS(Py_SIZE(a));
-        while (--i >= 0 && a->ob_digit[i] == b->ob_digit[i])
+        while (--i > 0 && a->ob_digit[i] == b->ob_digit[i])
             ;
-        if (i < 0)
-            sign = 0;
-        else {
-            sign = (sdigit)a->ob_digit[i] - (sdigit)b->ob_digit[i];
-            if (Py_SIZE(a) < 0)
-                sign = -sign;
-        }
+        sign = (sdigit)a->ob_digit[i] - (sdigit)b->ob_digit[i];
+        if (Py_SIZE(a) < 0)
+            sign = -sign;
     }
-    return sign < 0 ? -1 : sign > 0 ? 1 : 0;
+    return sign;
 }
 
 static PyObject *

From 99858bf705cdac3e02221fd69da4620ce435184d Mon Sep 17 00:00:00 2001
From: hongweipeng <961365124@qq.com>
Date: Sun, 15 Sep 2019 18:34:18 +0800
Subject: [PATCH 2/6] C code requires braces

---
 Objects/longobject.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 02546d913daf70..19525646f76db9 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3041,8 +3041,9 @@ long_compare(PyLongObject *a, PyLongObject *b)
         while (--i > 0 && a->ob_digit[i] == b->ob_digit[i])
             ;
         sign = (sdigit)a->ob_digit[i] - (sdigit)b->ob_digit[i];
-        if (Py_SIZE(a) < 0)
+        if (Py_SIZE(a) < 0) {
             sign = -sign;
+        }
     }
     return sign;
 }

From 5dc0e85b99a942bc6316c765ed812f85fa1762bb Mon Sep 17 00:00:00 2001
From: hongweipeng <961365124@qq.com>
Date: Tue, 17 Sep 2019 22:42:59 +0800
Subject: [PATCH 3/6] rewrite long_compare

---
 .../2019-09-15-01-30-06.bpo-35696.1iK_1H.rst  |  2 +-
 Objects/longobject.c                          | 23 ++++++++-----------
 2 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst b/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst
index 729824cc3a4601..e75db9eb40f39e 100644
--- a/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst	
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst	
@@ -1 +1 @@
-Slightly improve perfomance of long_compare. Patch by hongweipeng.
+Slightly improve perfomance of ``long_compare()``. Patch by hongweipeng and Sergey Fedoseev.
diff --git a/Objects/longobject.c b/Objects/longobject.c
index 19525646f76db9..e8b2cc6cfb02f9 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3028,22 +3028,16 @@ PyLong_AsDouble(PyObject *v)
 
 /* Methods */
 
-static int
+static Py_ssize_t
 long_compare(PyLongObject *a, PyLongObject *b)
 {
-    Py_ssize_t sign;
-
-    if (Py_SIZE(a) != Py_SIZE(b)) {
-        sign = Py_SIZE(a) - Py_SIZE(b);
-    }
-    else {
+    Py_ssize_t sign = Py_SIZE(a) - Py_SIZE(b);
+    if (!sign) {
         Py_ssize_t i = Py_ABS(Py_SIZE(a));
-        while (--i > 0 && a->ob_digit[i] == b->ob_digit[i])
+        sdigit diff = 0;
+        while (--i >= 0 && !(diff = (sdigit) a->ob_digit[i] - (sdigit) b->ob_digit[i]))
             ;
-        sign = (sdigit)a->ob_digit[i] - (sdigit)b->ob_digit[i];
-        if (Py_SIZE(a) < 0) {
-            sign = -sign;
-        }
+        sign = Py_SIZE(a) < 0 ? -diff : diff;
     }
     return sign;
 }
@@ -3051,7 +3045,7 @@ long_compare(PyLongObject *a, PyLongObject *b)
 static PyObject *
 long_richcompare(PyObject *self, PyObject *other, int op)
 {
-    int result;
+    Py_ssize_t result;
     CHECK_BINOP(self, other);
     if (self == other)
         result = 0;
@@ -5207,7 +5201,8 @@ _PyLong_DivmodNear(PyObject *a, PyObject *b)
 {
     PyLongObject *quo = NULL, *rem = NULL;
     PyObject *twice_rem, *result, *temp;
-    int cmp, quo_is_odd, quo_is_neg;
+    int quo_is_odd, quo_is_neg;
+    Py_ssize_t cmp;
 
     /* Equivalent Python code:
 

From da73290d228ee89da95b1fcb44791a77b33f26e4 Mon Sep 17 00:00:00 2001
From: hongweipeng <961365124@qq.com>
Date: Wed, 18 Sep 2019 00:14:04 +0800
Subject: [PATCH 4/6] code review

---
 Objects/longobject.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index e8b2cc6cfb02f9..353915437eb998 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3035,8 +3035,12 @@ long_compare(PyLongObject *a, PyLongObject *b)
     if (!sign) {
         Py_ssize_t i = Py_ABS(Py_SIZE(a));
         sdigit diff = 0;
-        while (--i >= 0 && !(diff = (sdigit) a->ob_digit[i] - (sdigit) b->ob_digit[i]))
-            ;
+        while (--i >= 0) {
+            diff = (sdigit) a->ob_digit[i] - (sdigit) b->ob_digit[i];
+            if (diff) {
+                break;
+            }
+        }
         sign = Py_SIZE(a) < 0 ? -diff : diff;
     }
     return sign;

From 8996ee561b053864b6be69da1b4325f60ffeb027 Mon Sep 17 00:00:00 2001
From: hongweipeng <961365124@qq.com>
Date: Wed, 18 Sep 2019 11:58:40 +0800
Subject: [PATCH 5/6] remove news

---
 .../Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst   | 1 -
 1 file changed, 1 deletion(-)
 delete mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst b/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst
deleted file mode 100644
index e75db9eb40f39e..00000000000000
--- a/Misc/NEWS.d/next/Core and Builtins/2019-09-15-01-30-06.bpo-35696.1iK_1H.rst	
+++ /dev/null
@@ -1 +0,0 @@
-Slightly improve perfomance of ``long_compare()``. Patch by hongweipeng and Sergey Fedoseev.

From 2fb685640a7ccc357c643381fe84125e9795a679 Mon Sep 17 00:00:00 2001
From: hongweipeng <961365124@qq.com>
Date: Wed, 18 Sep 2019 14:41:14 +0800
Subject: [PATCH 6/6] code review

---
 Objects/longobject.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 353915437eb998..f2f6f9540892ee 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3028,11 +3028,15 @@ PyLong_AsDouble(PyObject *v)
 
 /* Methods */
 
+/* if a < b, return a negative number
+   if a == b, return 0
+   if a > b, return a positive number */
+
 static Py_ssize_t
 long_compare(PyLongObject *a, PyLongObject *b)
 {
     Py_ssize_t sign = Py_SIZE(a) - Py_SIZE(b);
-    if (!sign) {
+    if (sign == 0) {
         Py_ssize_t i = Py_ABS(Py_SIZE(a));
         sdigit diff = 0;
         while (--i >= 0) {