[Python-checkins] bpo-47012: speed up iteration of bytes and bytearray (GH-31867)

[sweeneyde]

https://github.com/python/cpython/commit/bd1cf6ecee76bcdce87b4f69567b95756ecf5a4c
commit: bd1cf6ecee76bcdce87b4f69567b95756ecf5a4c
branch: main
author: Kumar Aditya <59607654+kumaraditya303 at users.noreply.github.com>
committer: sweeneyde <36520290+sweeneyde at users.noreply.github.com>
date: 2022-03-23T04:30:05-04:00
summary:

bpo-47012: speed up iteration of bytes and bytearray (GH-31867)

files:
A Misc/NEWS.d/next/Core and Builtins/2022-03-14-11-15-11.bpo-47012.5L6NoE.rst
M Include/internal/pycore_long.h
M Objects/bytearrayobject.c
M Objects/bytesobject.c

diff --git a/Include/internal/pycore_long.h b/Include/internal/pycore_long.h
index 436bf08468599..a33762402491b 100644
--- a/Include/internal/pycore_long.h
+++ b/Include/internal/pycore_long.h
@@ -23,8 +23,9 @@ extern void _PyLong_FiniTypes(PyInterpreterState *interp);
 #define _PyLong_SMALL_INTS _Py_SINGLETON(small_ints)
 
 // _PyLong_GetZero() and _PyLong_GetOne() must always be available
-#if _PY_NSMALLPOSINTS < 2
-#  error "_PY_NSMALLPOSINTS must be greater than 1"
+// _PyLong_FromUnsignedChar must always be available
+#if _PY_NSMALLPOSINTS < 257
+#  error "_PY_NSMALLPOSINTS must be greater than or equal to 257"
 #endif
 
 // Return a borrowed reference to the zero singleton.
@@ -37,6 +38,11 @@ static inline PyObject* _PyLong_GetZero(void)
 static inline PyObject* _PyLong_GetOne(void)
 { return (PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS+1]; }
 
+static inline PyObject* _PyLong_FromUnsignedChar(unsigned char i)
+{
+    return Py_NewRef((PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS+i]);
+}
+
 PyObject *_PyLong_Add(PyLongObject *left, PyLongObject *right);
 PyObject *_PyLong_Multiply(PyLongObject *left, PyLongObject *right);
 PyObject *_PyLong_Subtract(PyLongObject *left, PyLongObject *right);
diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-03-14-11-15-11.bpo-47012.5L6NoE.rst b/Misc/NEWS.d/next/Core and Builtins/2022-03-14-11-15-11.bpo-47012.5L6NoE.rst
new file mode 100644
index 0000000000000..f85487f8d3ae7
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-03-14-11-15-11.bpo-47012.5L6NoE.rst	
@@ -0,0 +1 @@
+Speed up iteration of :class:`bytes` and :class:`bytearray` by 30%. Patch by Kumar Aditya.
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index ba2d347dbd7a8..cbe673acd0a3a 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -6,6 +6,7 @@
 #include "pycore_bytes_methods.h"
 #include "pycore_object.h"        // _PyObject_GC_UNTRACK()
 #include "pycore_strhex.h"        // _Py_strhex_with_sep()
+#include "pycore_long.h"          // _PyLong_FromUnsignedChar()
 #include "bytesobject.h"
 
 /*[clinic input]
@@ -2428,7 +2429,6 @@ static PyObject *
 bytearrayiter_next(bytesiterobject *it)
 {
     PyByteArrayObject *seq;
-    PyObject *item;
 
     assert(it != NULL);
     seq = it->it_seq;
@@ -2437,11 +2437,8 @@ bytearrayiter_next(bytesiterobject *it)
     assert(PyByteArray_Check(seq));
 
     if (it->it_index < PyByteArray_GET_SIZE(seq)) {
-        item = PyLong_FromLong(
-            (unsigned char)PyByteArray_AS_STRING(seq)[it->it_index]);
-        if (item != NULL)
-            ++it->it_index;
-        return item;
+        return _PyLong_FromUnsignedChar(
+            (unsigned char)PyByteArray_AS_STRING(seq)[it->it_index++]);
     }
 
     it->it_seq = NULL;
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index fd1c58c2f233e..003953244a885 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -3133,7 +3133,7 @@ striter_next(striterobject *it)
     assert(PyBytes_Check(seq));
 
     if (it->it_index < PyBytes_GET_SIZE(seq)) {
-        return PyLong_FromLong(
+        return _PyLong_FromUnsignedChar(
             (unsigned char)seq->ob_sval[it->it_index++]);
     }