From 7b11d7d64675b5d84c6a35ba2e18783b27227d58 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Sat, 11 Dec 2021 12:05:54 +0800
Subject: [PATCH 01/16] Perf: Accelerate binary shift op.

---
 Objects/longobject.c | 96 +++++++++++++++++++++++++++++---------------
 1 file changed, 64 insertions(+), 32 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index f6d5e7648be16f..f36165c47ac140 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -32,7 +32,9 @@ static inline stwodigits
 medium_value(PyLongObject *x)
 {
     assert(IS_MEDIUM_VALUE(x));
-    return ((stwodigits)Py_SIZE(x)) * x->ob_digit[0];
+    Py_ssize_t s = Py_SIZE(x);
+    stwodigits d = x->ob_digit[0];
+    return s == 1 ? d : s == -1 ? -d : 0;
 }
 
 #define IS_SMALL_INT(ival) (-_PY_NSMALLNEGINTS <= (ival) && (ival) < _PY_NSMALLPOSINTS)
@@ -45,7 +47,7 @@ static inline int is_medium_int(stwodigits x)
     return x_plus_mask < ((twodigits)PyLong_MASK) + PyLong_BASE;
 }
 
-static PyObject *
+static inline PyObject *
 get_small_int(sdigit ival)
 {
     assert(IS_SMALL_INT(ival));
@@ -54,7 +56,7 @@ get_small_int(sdigit ival)
     return v;
 }
 
-static PyLongObject *
+static inline PyLongObject *
 maybe_small_long(PyLongObject *v)
 {
     if (v && IS_MEDIUM_VALUE(v)) {
@@ -4491,38 +4493,58 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
 {
     PyLongObject *z = NULL;
     Py_ssize_t newsize, hishift, i, j;
-    digit lomask, himask;
+    digit lomask, himask, omitmark;
 
-    if (Py_SIZE(a) < 0) {
-        /* Right shifting negative numbers is harder */
-        PyLongObject *a1, *a2;
-        a1 = (PyLongObject *) long_invert(a);
-        if (a1 == NULL)
-            return NULL;
-        a2 = (PyLongObject *) long_rshift1(a1, wordshift, remshift);
-        Py_DECREF(a1);
-        if (a2 == NULL)
-            return NULL;
-        z = (PyLongObject *) long_invert(a2);
-        Py_DECREF(a2);
+    /* for a positive integrate x
+         -x >> m = -(x >> m)      when x is two's pow
+                 = -(x >> m) -1   otherwise */
+
+    if (IS_MEDIUM_VALUE(a)) {
+        stwodigits sval;
+        if (wordshift > 0)
+            return get_small_int((sdigit)Py_SIZE(a) >> 1);
+
+        sval = medium_value(a) >> remshift;
+        if (IS_SMALL_INT(sval))
+            return get_small_int((sdigit)sval);
+
+        z = _PyLong_New(Py_SIZE(a));
+        z->ob_digit[0] = a->ob_digit[0] >> remshift;
+        if (Py_SIZE(a) < 0 && (a->ob_digit[0] & ~(PyLong_MASK << remshift)))
+            z->ob_digit[0] += 1;
+        return (PyObject *)z;
     }
-    else {
-        newsize = Py_SIZE(a) - wordshift;
-        if (newsize <= 0)
-            return PyLong_FromLong(0);
-        hishift = PyLong_SHIFT - remshift;
-        lomask = ((digit)1 << hishift) - 1;
-        himask = PyLong_MASK ^ lomask;
-        z = _PyLong_New(newsize);
-        if (z == NULL)
-            return NULL;
-        for (i = 0, j = wordshift; i < newsize; i++, j++) {
-            z->ob_digit[i] = (a->ob_digit[j] >> remshift) & lomask;
-            if (i+1 < newsize)
-                z->ob_digit[i] |= (a->ob_digit[j+1] << hishift) & himask;
+
+    newsize = Py_ABS(Py_SIZE(a)) - wordshift;
+    if (newsize <= 0)
+        return PyLong_FromLong(0);
+    z = _PyLong_New(newsize);
+    if (z == NULL)
+        return NULL;
+
+    hishift = PyLong_SHIFT - remshift;
+    lomask = ((digit)1 << hishift) - 1;
+    himask = PyLong_MASK ^ lomask;
+    for (i = 0, j = wordshift; i < newsize; i++, j++) {
+        z->ob_digit[i] = (a->ob_digit[j] >> remshift) & lomask;
+        if (i + 1 < newsize)
+            z->ob_digit[i] |= (a->ob_digit[j + 1] << hishift) & himask;
+    }
+
+    if (Py_SIZE(a) < 0) {
+        Py_SET_SIZE(z, -newsize);
+        omitmark = a->ob_digit[wordshift] & ((1 << remshift) - 1);
+        for (j = 0; omitmark == 0 && j < wordshift; j++)
+            omitmark |= a->ob_digit[j];
+        if (omitmark) {
+            Py_DECREF(z);
+            z = (PyLongObject *) long_sub(z, (PyLongObject *)_PyLong_GetOne());
+            if (z == NULL)
+                return NULL;
         }
-        z = maybe_small_long(long_normalize(z));
     }
+
+    z = maybe_small_long(long_normalize(z));
     return (PyObject *)z;
 }
 
@@ -4565,11 +4587,21 @@ _PyLong_Rshift(PyObject *a, size_t shiftby)
 static PyObject *
 long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
 {
-    /* This version due to Tim Peters */
     PyLongObject *z = NULL;
     Py_ssize_t oldsize, newsize, i, j;
     twodigits accum;
 
+    if (wordshift == 0 && IS_MEDIUM_VALUE(a) &&
+        (a->ob_digit[0] & ~(PyLong_MASK >> remshift)) == 0) {
+        stwodigits sval = medium_value(a) << remshift;
+        if (IS_SMALL_INT(sval))
+            return get_small_int((sdigit)sval);
+        z = _PyLong_New(Py_SIZE(a));
+        z->ob_digit[0] = a->ob_digit[0] << remshift;
+        return (PyObject *)z;
+    }
+
+    /* This version due to Tim Peters */
     oldsize = Py_ABS(Py_SIZE(a));
     newsize = oldsize + wordshift;
     if (remshift)

From 403652a9672037daaa7dfd013009a0be645ac845 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Sun, 12 Dec 2021 12:59:26 +0800
Subject: [PATCH 02/16] Fix: Ubuntu gcc segment fault.

---
 Objects/longobject.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index f36165c47ac140..4a00a5a13f79cb 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4508,8 +4508,9 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
         if (IS_SMALL_INT(sval))
             return get_small_int((sdigit)sval);
 
-        z = _PyLong_New(Py_SIZE(a));
-        z->ob_digit[0] = a->ob_digit[0] >> remshift;
+        z = _PyLong_New(Py_ABS(Py_SIZE(a)));
+        Py_SET_SIZE(z, Py_SIZE(a));
+        z->ob_digit[0] = (digit)(a->ob_digit[0] >> remshift);
         if (Py_SIZE(a) < 0 && (a->ob_digit[0] & ~(PyLong_MASK << remshift)))
             z->ob_digit[0] += 1;
         return (PyObject *)z;
@@ -4537,8 +4538,9 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
         for (j = 0; omitmark == 0 && j < wordshift; j++)
             omitmark |= a->ob_digit[j];
         if (omitmark) {
-            Py_DECREF(z);
-            z = (PyLongObject *) long_sub(z, (PyLongObject *)_PyLong_GetOne());
+            PyLongObject *z0 = z;
+            z = (PyLongObject *) long_sub(z0, (PyLongObject *)_PyLong_GetOne());
+            Py_DECREF(z0);
             if (z == NULL)
                 return NULL;
         }
@@ -4596,8 +4598,9 @@ long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
         stwodigits sval = medium_value(a) << remshift;
         if (IS_SMALL_INT(sval))
             return get_small_int((sdigit)sval);
-        z = _PyLong_New(Py_SIZE(a));
-        z->ob_digit[0] = a->ob_digit[0] << remshift;
+        z = _PyLong_New(Py_ABS(Py_SIZE(a)));
+        Py_SET_SIZE(z, Py_SIZE(a));
+        z->ob_digit[0] = (digit)(a->ob_digit[0] << remshift);
         return (PyObject *)z;
     }
 

From dcd27965954068aaa79b0a84bfae807bea5f1d58 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Sun, 12 Dec 2021 13:18:41 +0800
Subject: [PATCH 03/16] Let PyLong_New accept a negtive size.

---
 Objects/longobject.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 4a00a5a13f79cb..61405db0eae41d 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -116,14 +116,15 @@ PyLongObject *
 _PyLong_New(Py_ssize_t size)
 {
     PyLongObject *result;
-    if (size > (Py_ssize_t)MAX_LONG_DIGITS) {
+    Py_ssize_t size_abs = Py_ABS(size);
+    if (size_abs > (Py_ssize_t)MAX_LONG_DIGITS) {
         PyErr_SetString(PyExc_OverflowError,
                         "too many digits in integer");
         return NULL;
     }
     /* Fast operations for single digit integers (including zero)
      * assume that there is always at least one digit present. */
-    Py_ssize_t ndigits = size ? size : 1;
+    Py_ssize_t ndigits = size_abs ? size_abs : 1;
     /* Number of bytes needed is: offsetof(PyLongObject, ob_digit) +
        sizeof(digit)*size.  Previous incarnations of this code used
        sizeof(PyVarObject) instead of the offsetof, but this risks being
@@ -4508,8 +4509,7 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
         if (IS_SMALL_INT(sval))
             return get_small_int((sdigit)sval);
 
-        z = _PyLong_New(Py_ABS(Py_SIZE(a)));
-        Py_SET_SIZE(z, Py_SIZE(a));
+        z = _PyLong_New(Py_SIZE(a));
         z->ob_digit[0] = (digit)(a->ob_digit[0] >> remshift);
         if (Py_SIZE(a) < 0 && (a->ob_digit[0] & ~(PyLong_MASK << remshift)))
             z->ob_digit[0] += 1;
@@ -4598,8 +4598,7 @@ long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
         stwodigits sval = medium_value(a) << remshift;
         if (IS_SMALL_INT(sval))
             return get_small_int((sdigit)sval);
-        z = _PyLong_New(Py_ABS(Py_SIZE(a)));
-        Py_SET_SIZE(z, Py_SIZE(a));
+        z = _PyLong_New(Py_SIZE(a));
         z->ob_digit[0] = (digit)(a->ob_digit[0] << remshift);
         return (PyObject *)z;
     }

From 25bbf4de2f11c0177c8e5f2c27338a8ea6182730 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Sun, 12 Dec 2021 20:04:35 +0800
Subject: [PATCH 04/16] Fix: Use Py_ARITHMETIC_RIGHT_SHIFT to avoid the
 undefined padding bahavior of C right shift operator.

---
 Objects/longobject.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 61405db0eae41d..b4edf7e86601ee 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4497,15 +4497,15 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
     digit lomask, himask, omitmark;
 
     /* for a positive integrate x
-         -x >> m = -(x >> m)      when x is two's pow
-                 = -(x >> m) -1   otherwise */
+         -x >> m = -(x >> m)      when the dropped bits are all zeros,
+                 = -(x >> m) -1   otherwise. */
 
     if (IS_MEDIUM_VALUE(a)) {
         stwodigits sval;
         if (wordshift > 0)
-            return get_small_int((sdigit)Py_SIZE(a) >> 1);
+            return get_small_int(-(Py_SIZE(a) < 0));
 
-        sval = medium_value(a) >> remshift;
+        sval = Py_ARITHMETIC_RIGHT_SHIFT(stwodigits, medium_value(a), remshift);
         if (IS_SMALL_INT(sval))
             return get_small_int((sdigit)sval);
 

From b2ef93da5083531d2f7dd5c1d7eb08523a57ee30 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Sun, 12 Dec 2021 20:10:25 +0800
Subject: [PATCH 05/16] Style: PEP7: add braces.

---
 Objects/longobject.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index b4edf7e86601ee..1b00f1f36c9ace 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4502,47 +4502,53 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
 
     if (IS_MEDIUM_VALUE(a)) {
         stwodigits sval;
-        if (wordshift > 0)
+        if (wordshift > 0) {
             return get_small_int(-(Py_SIZE(a) < 0));
-
+        }
         sval = Py_ARITHMETIC_RIGHT_SHIFT(stwodigits, medium_value(a), remshift);
-        if (IS_SMALL_INT(sval))
+        if (IS_SMALL_INT(sval)) {
             return get_small_int((sdigit)sval);
-
+        }
         z = _PyLong_New(Py_SIZE(a));
         z->ob_digit[0] = (digit)(a->ob_digit[0] >> remshift);
-        if (Py_SIZE(a) < 0 && (a->ob_digit[0] & ~(PyLong_MASK << remshift)))
+        if (Py_SIZE(a) < 0 && (a->ob_digit[0] & ~(PyLong_MASK << remshift))) {
             z->ob_digit[0] += 1;
+        }
         return (PyObject *)z;
     }
 
     newsize = Py_ABS(Py_SIZE(a)) - wordshift;
-    if (newsize <= 0)
+    if (newsize <= 0) {
         return PyLong_FromLong(0);
+    }
     z = _PyLong_New(newsize);
-    if (z == NULL)
+    if (z == NULL) {
         return NULL;
+    }
 
     hishift = PyLong_SHIFT - remshift;
     lomask = ((digit)1 << hishift) - 1;
     himask = PyLong_MASK ^ lomask;
     for (i = 0, j = wordshift; i < newsize; i++, j++) {
         z->ob_digit[i] = (a->ob_digit[j] >> remshift) & lomask;
-        if (i + 1 < newsize)
+        if (i + 1 < newsize) {
             z->ob_digit[i] |= (a->ob_digit[j + 1] << hishift) & himask;
+        }
     }
 
     if (Py_SIZE(a) < 0) {
         Py_SET_SIZE(z, -newsize);
         omitmark = a->ob_digit[wordshift] & ((1 << remshift) - 1);
-        for (j = 0; omitmark == 0 && j < wordshift; j++)
+        for (j = 0; omitmark == 0 && j < wordshift; j++) {
             omitmark |= a->ob_digit[j];
+        }
         if (omitmark) {
             PyLongObject *z0 = z;
             z = (PyLongObject *) long_sub(z0, (PyLongObject *)_PyLong_GetOne());
             Py_DECREF(z0);
-            if (z == NULL)
+            if (z == NULL) {
                 return NULL;
+            }
         }
     }
 
@@ -4596,8 +4602,9 @@ long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
     if (wordshift == 0 && IS_MEDIUM_VALUE(a) &&
         (a->ob_digit[0] & ~(PyLong_MASK >> remshift)) == 0) {
         stwodigits sval = medium_value(a) << remshift;
-        if (IS_SMALL_INT(sval))
+        if (IS_SMALL_INT(sval)) {
             return get_small_int((sdigit)sval);
+        }
         z = _PyLong_New(Py_SIZE(a));
         z->ob_digit[0] = (digit)(a->ob_digit[0] << remshift);
         return (PyObject *)z;

From 7d2203f2777e1650c36c3c3a20856c7752a4ab9d Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Tue, 14 Dec 2021 00:00:07 +0800
Subject: [PATCH 06/16] Fix: Bypass undefined shift operator behavior

---
 Objects/longobject.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 1b00f1f36c9ace..b496aa84e32daf 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4538,7 +4538,7 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
 
     if (Py_SIZE(a) < 0) {
         Py_SET_SIZE(z, -newsize);
-        omitmark = a->ob_digit[wordshift] & ((1 << remshift) - 1);
+        omitmark = a->ob_digit[wordshift] & (((digit)1 << remshift) - 1);
         for (j = 0; omitmark == 0 && j < wordshift; j++) {
             omitmark |= a->ob_digit[j];
         }
@@ -4601,7 +4601,8 @@ long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
 
     if (wordshift == 0 && IS_MEDIUM_VALUE(a) &&
         (a->ob_digit[0] & ~(PyLong_MASK >> remshift)) == 0) {
-        stwodigits sval = medium_value(a) << remshift;
+        stwodigits sval = (stwodigits)((twodigits)medium_value(a) << remshift);
+        // bypass undefined shift operator behavior
         if (IS_SMALL_INT(sval)) {
             return get_small_int((sdigit)sval);
         }

From 932ad87e7c431cbeae649da01cc0267d41200c8c Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Wed, 22 Dec 2021 23:33:44 +0800
Subject: [PATCH 07/16] Revert "Let PyLong_New accept a negtive size."

This reverts commit dcd27965954068aaa79b0a84bfae807bea5f1d58.
---
 Objects/longobject.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index b496aa84e32daf..b7752317fda775 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -116,15 +116,14 @@ PyLongObject *
 _PyLong_New(Py_ssize_t size)
 {
     PyLongObject *result;
-    Py_ssize_t size_abs = Py_ABS(size);
-    if (size_abs > (Py_ssize_t)MAX_LONG_DIGITS) {
+    if (size > (Py_ssize_t)MAX_LONG_DIGITS) {
         PyErr_SetString(PyExc_OverflowError,
                         "too many digits in integer");
         return NULL;
     }
     /* Fast operations for single digit integers (including zero)
      * assume that there is always at least one digit present. */
-    Py_ssize_t ndigits = size_abs ? size_abs : 1;
+    Py_ssize_t ndigits = size ? size : 1;
     /* Number of bytes needed is: offsetof(PyLongObject, ob_digit) +
        sizeof(digit)*size.  Previous incarnations of this code used
        sizeof(PyVarObject) instead of the offsetof, but this risks being
@@ -4509,7 +4508,8 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
         if (IS_SMALL_INT(sval)) {
             return get_small_int((sdigit)sval);
         }
-        z = _PyLong_New(Py_SIZE(a));
+        z = _PyLong_New(Py_ABS(Py_SIZE(a)));
+        Py_SET_SIZE(z, Py_SIZE(a));
         z->ob_digit[0] = (digit)(a->ob_digit[0] >> remshift);
         if (Py_SIZE(a) < 0 && (a->ob_digit[0] & ~(PyLong_MASK << remshift))) {
             z->ob_digit[0] += 1;
@@ -4606,7 +4606,8 @@ long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
         if (IS_SMALL_INT(sval)) {
             return get_small_int((sdigit)sval);
         }
-        z = _PyLong_New(Py_SIZE(a));
+        z = _PyLong_New(Py_ABS(Py_SIZE(a)));
+        Py_SET_SIZE(z, Py_SIZE(a));
         z->ob_digit[0] = (digit)(a->ob_digit[0] << remshift);
         return (PyObject *)z;
     }

From 596b8cfba788ceb2614348d93beb0e9084bc8684 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Wed, 22 Dec 2021 23:38:03 +0800
Subject: [PATCH 08/16] Revert: Remove additional inline keywords.

---
 Objects/longobject.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index b7752317fda775..44d82266cff229 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -47,7 +47,7 @@ static inline int is_medium_int(stwodigits x)
     return x_plus_mask < ((twodigits)PyLong_MASK) + PyLong_BASE;
 }
 
-static inline PyObject *
+static PyObject *
 get_small_int(sdigit ival)
 {
     assert(IS_SMALL_INT(ival));
@@ -56,7 +56,7 @@ get_small_int(sdigit ival)
     return v;
 }
 
-static inline PyLongObject *
+static PyLongObject *
 maybe_small_long(PyLongObject *v)
 {
     if (v && IS_MEDIUM_VALUE(v)) {

From 6545e9a83ca95ad27b003a5ad4d789ae2bd3ff20 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Thu, 23 Dec 2021 11:45:16 +0800
Subject: [PATCH 09/16] Refactor: Simpilify code by using _PyLong_FromSTwoDigit

---
 Objects/longobject.c | 33 +++++++++------------------------
 1 file changed, 9 insertions(+), 24 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 44d82266cff229..124a8a358dd50b 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4495,28 +4495,19 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
     Py_ssize_t newsize, hishift, i, j;
     digit lomask, himask, omitmark;
 
-    /* for a positive integrate x
-         -x >> m = -(x >> m)      when the dropped bits are all zeros,
-                 = -(x >> m) -1   otherwise. */
-
     if (IS_MEDIUM_VALUE(a)) {
-        stwodigits sval;
+        stwodigits x;
         if (wordshift > 0) {
             return get_small_int(-(Py_SIZE(a) < 0));
         }
-        sval = Py_ARITHMETIC_RIGHT_SHIFT(stwodigits, medium_value(a), remshift);
-        if (IS_SMALL_INT(sval)) {
-            return get_small_int((sdigit)sval);
-        }
-        z = _PyLong_New(Py_ABS(Py_SIZE(a)));
-        Py_SET_SIZE(z, Py_SIZE(a));
-        z->ob_digit[0] = (digit)(a->ob_digit[0] >> remshift);
-        if (Py_SIZE(a) < 0 && (a->ob_digit[0] & ~(PyLong_MASK << remshift))) {
-            z->ob_digit[0] += 1;
-        }
-        return (PyObject *)z;
+        x = Py_ARITHMETIC_RIGHT_SHIFT(stwodigits, medium_value(a), remshift);
+        return _PyLong_FromSTwoDigits(x);
     }
 
+    /* for a positive integrate x
+     -x >> m = -(x >> m)      when the dropped bits are all zeros,
+             = -(x >> m) -1   otherwise. */
+
     newsize = Py_ABS(Py_SIZE(a)) - wordshift;
     if (newsize <= 0) {
         return PyLong_FromLong(0);
@@ -4601,15 +4592,9 @@ long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
 
     if (wordshift == 0 && IS_MEDIUM_VALUE(a) &&
         (a->ob_digit[0] & ~(PyLong_MASK >> remshift)) == 0) {
-        stwodigits sval = (stwodigits)((twodigits)medium_value(a) << remshift);
         // bypass undefined shift operator behavior
-        if (IS_SMALL_INT(sval)) {
-            return get_small_int((sdigit)sval);
-        }
-        z = _PyLong_New(Py_ABS(Py_SIZE(a)));
-        Py_SET_SIZE(z, Py_SIZE(a));
-        z->ob_digit[0] = (digit)(a->ob_digit[0] << remshift);
-        return (PyObject *)z;
+        stwodigits x = (stwodigits)((twodigits)medium_value(a) << remshift);
+        return _PyLong_FromSTwoDigits(x);
     }
 
     /* This version due to Tim Peters */

From 7f80cd924c96046f61077b4de68894c4fb7f185a Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Thu, 23 Dec 2021 12:03:13 +0800
Subject: [PATCH 10/16] Fix: Wrong rshift result.

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

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 124a8a358dd50b..7404d136611172 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4510,7 +4510,7 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
 
     newsize = Py_ABS(Py_SIZE(a)) - wordshift;
     if (newsize <= 0) {
-        return PyLong_FromLong(0);
+        return get_small_int(-(Py_SIZE(a) < 0));
     }
     z = _PyLong_New(newsize);
     if (z == NULL) {

From b24c7dcc7da47c69519a693401c9f66af742a030 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Thu, 23 Dec 2021 12:03:40 +0800
Subject: [PATCH 11/16] Test: More testcases.

---
 Lib/test/test_long.py | 63 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 61 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_long.py b/Lib/test/test_long.py
index e5c4d7fc4220f8..3c8e9e22e17a19 100644
--- a/Lib/test/test_long.py
+++ b/Lib/test/test_long.py
@@ -946,8 +946,13 @@ def test_huge_lshift(self, size):
         self.assertEqual(1 << (sys.maxsize + 1000), 1 << 1000 << sys.maxsize)
 
     def test_huge_rshift(self):
-        self.assertEqual(42 >> (1 << 1000), 0)
-        self.assertEqual((-42) >> (1 << 1000), -1)
+        huge_shift = 1 << 1000
+        self.assertEqual(42 >> huge_shift, 0)
+        self.assertEqual((-42) >> huge_shift, -1)
+        self.assertEqual(1123 >> huge_shift, 0)
+        self.assertEqual((-1123) >> huge_shift, -1)
+        self.assertEqual(2**128 >> huge_shift, 0)
+        self.assertEqual(-2**128 >> huge_shift, -1)
 
     @support.cpython_only
     @support.bigmemtest(sys.maxsize + 500, memuse=2/15, dry_run=False)
@@ -956,6 +961,60 @@ def test_huge_rshift_of_huge(self, size):
         self.assertEqual(huge >> (sys.maxsize + 1), (1 << 499) + 5)
         self.assertEqual(huge >> (sys.maxsize + 1000), 0)
 
+    def test_small_rshift(self):
+        self.assertEqual(42 >> 1, 21)
+        self.assertEqual((-42) >> 1, -21)
+        self.assertEqual(43 >> 1, 21)
+        self.assertEqual((-43) >> 1, -22)
+
+        self.assertEqual(1122 >> 1, 561)
+        self.assertEqual((-1122) >> 1, -561)
+        self.assertEqual(1123 >> 1, 561)
+        self.assertEqual((-1123) >> 1, -562)
+
+        self.assertEqual(2**128 >> 1, 2**127)
+        self.assertEqual(-2**128 >> 1, -2**127)
+        self.assertEqual((2**128 + 1) >> 1, 2**127)
+        self.assertEqual(-(2**128 + 1) >> 1, -2**127 - 1)
+
+    def test_medium_rshift(self):
+        self.assertEqual(42 >> 9, 0)
+        self.assertEqual((-42) >> 9, -1)
+        self.assertEqual(1122 >> 9, 2)
+        self.assertEqual((-1122) >> 9, -3)
+        self.assertEqual(2**128 >> 9, 2**119)
+        self.assertEqual(-2**128 >> 9, -2**119)
+
+    def test_big_rshift(self):
+        self.assertEqual(42 >> 32, 0)
+        self.assertEqual((-42) >> 32, -1)
+        self.assertEqual(1122 >> 32, 0)
+        self.assertEqual((-1122) >> 32, -1)
+        self.assertEqual(2**128 >> 32, 2**96)
+        self.assertEqual(-2**128 >> 32, -2**96)
+
+    def test_small_lshift(self):
+        self.assertEqual(42 << 1, 84)
+        self.assertEqual((-42) << 1, -84)
+        self.assertEqual(561 << 1, 1122)
+        self.assertEqual((-561) << 1, -1122)
+        self.assertEqual(2**127 << 1, 2**128)
+        self.assertEqual(-2**127 << 1, -2**128)
+
+    def test_medium_lshift(self):
+        self.assertEqual(42 << 9, 21504)
+        self.assertEqual((-42) << 9, -21504)
+        self.assertEqual(1122 << 9, 574464)
+        self.assertEqual((-1122) << 9, -574464)
+
+    def test_big_lshift(self):
+        self.assertEqual(42 << 32, 42 * 2**32)
+        self.assertEqual((-42) << 32, -42 * 2**32)
+        self.assertEqual(1122 << 32, 1122 * 2**32)
+        self.assertEqual((-1122) << 32, -1122 * 2**32)
+        self.assertEqual(2**128 << 32, 2**160)
+        self.assertEqual(-2**128 << 32, -2**160)
+
     @support.cpython_only
     def test_small_ints_in_huge_calculation(self):
         a = 2 ** 100

From c00a963661a9a48a9b29119b5f7eded570a37d77 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Fri, 24 Dec 2021 00:54:13 +0800
Subject: [PATCH 12/16] Refactor: Clean code.

---
 Objects/longobject.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 7404d136611172..35db0b65bc893b 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4496,11 +4496,11 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
     digit lomask, himask, omitmark;
 
     if (IS_MEDIUM_VALUE(a)) {
-        stwodigits x;
-        if (wordshift > 0) {
-            return get_small_int(-(Py_SIZE(a) < 0));
-        }
-        x = Py_ARITHMETIC_RIGHT_SHIFT(stwodigits, medium_value(a), remshift);
+        stwodigits m, x;
+        digit shift;
+        m = medium_value(a);
+        shift = wordshift == 0 ? remshift : PyLong_SHIFT;
+        x = m < 0 ? ~(~m >> shift) : m >> shift;
         return _PyLong_FromSTwoDigits(x);
     }
 
@@ -4590,14 +4590,13 @@ long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
     Py_ssize_t oldsize, newsize, i, j;
     twodigits accum;
 
-    if (wordshift == 0 && IS_MEDIUM_VALUE(a) &&
-        (a->ob_digit[0] & ~(PyLong_MASK >> remshift)) == 0) {
+    if (wordshift == 0 && IS_MEDIUM_VALUE(a)) {
+        stwodigits m = medium_value(a);
         // bypass undefined shift operator behavior
-        stwodigits x = (stwodigits)((twodigits)medium_value(a) << remshift);
+        stwodigits x = m < 0 ? -(-m << remshift) : m << remshift;
         return _PyLong_FromSTwoDigits(x);
     }
 
-    /* This version due to Tim Peters */
     oldsize = Py_ABS(Py_SIZE(a));
     newsize = oldsize + wordshift;
     if (remshift)

From b7ad599894bdbf6aa3d78c7d37342f81de225f72 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Fri, 24 Dec 2021 00:59:09 +0800
Subject: [PATCH 13/16] Revert: Revert unrelated code.

---
 Objects/longobject.c | 66 +++++++++++++++++++-------------------------
 1 file changed, 28 insertions(+), 38 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 35db0b65bc893b..c945252d4a433a 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4493,7 +4493,7 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
 {
     PyLongObject *z = NULL;
     Py_ssize_t newsize, hishift, i, j;
-    digit lomask, himask, omitmark;
+    digit lomask, himask;
 
     if (IS_MEDIUM_VALUE(a)) {
         stwodigits m, x;
@@ -4504,46 +4504,36 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
         return _PyLong_FromSTwoDigits(x);
     }
 
-    /* for a positive integrate x
-     -x >> m = -(x >> m)      when the dropped bits are all zeros,
-             = -(x >> m) -1   otherwise. */
-
-    newsize = Py_ABS(Py_SIZE(a)) - wordshift;
-    if (newsize <= 0) {
-        return get_small_int(-(Py_SIZE(a) < 0));
-    }
-    z = _PyLong_New(newsize);
-    if (z == NULL) {
-        return NULL;
-    }
-
-    hishift = PyLong_SHIFT - remshift;
-    lomask = ((digit)1 << hishift) - 1;
-    himask = PyLong_MASK ^ lomask;
-    for (i = 0, j = wordshift; i < newsize; i++, j++) {
-        z->ob_digit[i] = (a->ob_digit[j] >> remshift) & lomask;
-        if (i + 1 < newsize) {
-            z->ob_digit[i] |= (a->ob_digit[j + 1] << hishift) & himask;
-        }
-    }
-
     if (Py_SIZE(a) < 0) {
-        Py_SET_SIZE(z, -newsize);
-        omitmark = a->ob_digit[wordshift] & (((digit)1 << remshift) - 1);
-        for (j = 0; omitmark == 0 && j < wordshift; j++) {
-            omitmark |= a->ob_digit[j];
-        }
-        if (omitmark) {
-            PyLongObject *z0 = z;
-            z = (PyLongObject *) long_sub(z0, (PyLongObject *)_PyLong_GetOne());
-            Py_DECREF(z0);
-            if (z == NULL) {
-                return NULL;
-            }
+        /* Right shifting negative numbers is harder */
+        PyLongObject *a1, *a2;
+        a1 = (PyLongObject *)long_invert(a);
+        if (a1 == NULL)
+            return NULL;
+        a2 = (PyLongObject *)long_rshift1(a1, wordshift, remshift);
+        Py_DECREF(a1);
+        if (a2 == NULL)
+            return NULL;
+        z = (PyLongObject *)long_invert(a2);
+        Py_DECREF(a2);
+    }
+    else {
+        newsize = Py_SIZE(a) - wordshift;
+        if (newsize <= 0)
+            return PyLong_FromLong(0);
+        hishift = PyLong_SHIFT - remshift;
+        lomask = ((digit)1 << hishift) - 1;
+        himask = PyLong_MASK ^ lomask;
+        z = _PyLong_New(newsize);
+        if (z == NULL)
+            return NULL;
+        for (i = 0, j = wordshift; i < newsize; i++, j++) {
+            z->ob_digit[i] = (a->ob_digit[j] >> remshift) & lomask;
+            if (i + 1 < newsize)
+                z->ob_digit[i] |= (a->ob_digit[j + 1] << hishift) & himask;
         }
+        z = maybe_small_long(long_normalize(z));
     }
-
-    z = maybe_small_long(long_normalize(z));
     return (PyObject *)z;
 }
 

From c359521056e3078b16f73a24c24a90e63784dc08 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Fri, 24 Dec 2021 20:26:21 +0800
Subject: [PATCH 14/16] Docs: A couple more things.

---
 Misc/ACKS                                              |  1 +
 .../2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst           |  2 ++
 Objects/longobject.c                                   | 10 +++++-----
 3 files changed, 8 insertions(+), 5 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst

diff --git a/Misc/ACKS b/Misc/ACKS
index 94a82a07506220..8baaf7304b603c 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1964,6 +1964,7 @@ Doug Wyatt
 Xiang Zhang
 Robert Xiao
 Florent Xicluna
+Xinhang Xu
 Arnon Yaari
 Alakshendra Yadav
 Hirokazu Yamamoto
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst b/Misc/NEWS.d/next/Core and Builtins/2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst
new file mode 100644
index 00000000000000..c660fea838e397
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst	
@@ -0,0 +1,2 @@
+Speed up shifting operation involving integrates less than
+:c:macro:`PyLong_BASE`.
diff --git a/Objects/longobject.c b/Objects/longobject.c
index c945252d4a433a..3d78e7f51de96d 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4507,14 +4507,14 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
     if (Py_SIZE(a) < 0) {
         /* Right shifting negative numbers is harder */
         PyLongObject *a1, *a2;
-        a1 = (PyLongObject *)long_invert(a);
+        a1 = (PyLongObject *) long_invert(a);
         if (a1 == NULL)
             return NULL;
-        a2 = (PyLongObject *)long_rshift1(a1, wordshift, remshift);
+        a2 = (PyLongObject *) long_rshift1(a1, wordshift, remshift);
         Py_DECREF(a1);
         if (a2 == NULL)
             return NULL;
-        z = (PyLongObject *)long_invert(a2);
+        z = (PyLongObject *) long_invert(a2);
         Py_DECREF(a2);
     }
     else {
@@ -4529,8 +4529,8 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
             return NULL;
         for (i = 0, j = wordshift; i < newsize; i++, j++) {
             z->ob_digit[i] = (a->ob_digit[j] >> remshift) & lomask;
-            if (i + 1 < newsize)
-                z->ob_digit[i] |= (a->ob_digit[j + 1] << hishift) & himask;
+            if (i+1 < newsize)
+                z->ob_digit[i] |= (a->ob_digit[j+1] << hishift) & himask;
         }
         z = maybe_small_long(long_normalize(z));
     }

From 241da4c272d4252a9cf71c3f29230152c50ce205 Mon Sep 17 00:00:00 2001
From: xuxinhang <xuxinhang4567@126.com>
Date: Fri, 24 Dec 2021 21:20:10 +0800
Subject: [PATCH 15/16] Revert: medium_value

---
 Objects/longobject.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 3d78e7f51de96d..d8faaedea34111 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -32,9 +32,7 @@ static inline stwodigits
 medium_value(PyLongObject *x)
 {
     assert(IS_MEDIUM_VALUE(x));
-    Py_ssize_t s = Py_SIZE(x);
-    stwodigits d = x->ob_digit[0];
-    return s == 1 ? d : s == -1 ? -d : 0;
+    return ((stwodigits)Py_SIZE(x)) * x->ob_digit[0];
 }
 
 #define IS_SMALL_INT(ival) (-_PY_NSMALLNEGINTS <= (ival) && (ival) < _PY_NSMALLPOSINTS)

From 9ed09aad05cb701c30995ed9516d0dfb241721ab Mon Sep 17 00:00:00 2001
From: Mark Dickinson <dickinsm@gmail.com>
Date: Mon, 27 Dec 2021 09:43:07 +0000
Subject: [PATCH 16/16] Add attribution; fix typo

---
 .../2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst                  | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst b/Misc/NEWS.d/next/Core and Builtins/2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst
index c660fea838e397..124138806f17d0 100644
--- a/Misc/NEWS.d/next/Core and Builtins/2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst	
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-12-24-20-21-45.bpo-46055.R0QMVQ.rst	
@@ -1,2 +1,2 @@
-Speed up shifting operation involving integrates less than
-:c:macro:`PyLong_BASE`.
+Speed up shifting operation involving integers less than
+:c:macro:`PyLong_BASE`. Patch by Xinhang Xu.