Inline PyObject_GetItem() for a ~10% speedup.

CHANGES.rst

@@ -18,6 +18,8 @@ Features added
 * The new TSS C-API in CPython 3.7 is supported and has been backported.
   Patch by Naotoshi Seo.  (Github issue #1932)
 
+* Subscripting (item access) is faster in some cases.
+
 * Some ``bytearray`` operations have been optimised similar to ``bytes``.
 
 * Safe integer loops (< range(2^30)) are optimised into C loops.

Cython/Compiler/ExprNodes.py

@@ -3904,7 +3904,10 @@ class IndexNode(_IndexingBaseNode):
                     function = "__Pyx_PyObject_Dict_GetItem"
                     utility_code = UtilityCode.load_cached("DictGetItem", "ObjectHandling.c")
                 else:
-                    function = "PyObject_GetItem"
+                    function = "__Pyx_PyObject_GetItem"
+                    code.globalstate.use_utility_code(
+                        TempitaUtilityCode.load_cached("GetItemInt", "ObjectHandling.c"))
+                    utility_code = UtilityCode.load_cached("ObjectGetItem", "ObjectHandling.c")
         elif self.type.is_unicode_char and self.base.type is unicode_type:
             assert self.index.type.is_int
             function = "__Pyx_GetItemInt_Unicode"

Cython/Utility/ObjectHandling.c

@@ -262,6 +262,49 @@ static CYTHON_INLINE int __Pyx_IterFinish(void) {
 #endif
 }
 
+
+/////////////// ObjectGetItem.proto ///////////////
+
+#if CYTHON_USE_TYPE_SLOTS
+static CYTHON_INLINE PyObject *__Pyx_PyObject_GetItem(PyObject *obj, PyObject* key);/*proto*/
+#else
+#define __Pyx_PyObject_GetItem(obj, key)  PyObject_GetItem(obj, key)
+#endif
+
+/////////////// ObjectGetItem ///////////////
+// //@requires: GetItemInt - added in IndexNode as it uses templating.
+
+#if CYTHON_USE_TYPE_SLOTS
+static PyObject *__Pyx_PyObject_GetIndex(PyObject *obj, PyObject* index) {
+    PySequenceMethods *m = Py_TYPE(obj)->tp_as_sequence;
+    if (likely(m && m->sq_item)) {
+        PyObject *runerr;
+        Py_ssize_t key_value = __Pyx_PyIndex_AsSsize_t(index);
+        if (likely(key_value != -1 || !(runerr = PyErr_Occurred()))) {
+            return __Pyx_GetItemInt_Fast(obj, key_value, 0, 1, 1);
+        }
+
+        // Error handling code -- only manage OverflowError differently.
+        if (PyErr_GivenExceptionMatches(runerr, PyExc_OverflowError)) {
+            PyErr_Clear();
+            PyErr_Format(PyExc_IndexError, "cannot fit '%.200s' into an index-sized integer", Py_TYPE(index)->tp_name);
+        }
+    } else {
+        PyErr_Format(PyExc_TypeError, "'%.200s' object is not subscriptable", Py_TYPE(obj)->tp_name);
+    }
+    return NULL;
+}
+
+static PyObject *__Pyx_PyObject_GetItem(PyObject *obj, PyObject* key) {
+    PyMappingMethods *m = Py_TYPE(obj)->tp_as_mapping;
+    if (likely(m && m->mp_subscript)) {
+        return m->mp_subscript(obj, key);
+    }
+    return __Pyx_PyObject_GetIndex(obj, key);
+}
+#endif
+
+
 /////////////// DictGetItem.proto ///////////////
 
 #if PY_MAJOR_VERSION >= 3 && !CYTHON_COMPILING_IN_PYPY