take multiplication out of the loop

eendebakpt · eendebakpt · commit 640643efcd8d · 2022-04-22T11:20:56.000+02:00
diff --git a/Include/internal/pycore_object.h b/Include/internal/pycore_object.h
@@ -254,13 +254,14 @@ static inline int _PyType_SUPPORTS_WEAKREFS(PyTypeObject *type) {
 
 /// Method to copy objects for specified number of times inside a buffer
 static inline void
-_objects_repeat(PyObject** items, Py_ssize_t copied, Py_ssize_t len_dest)
+_objects_repeat(char *dest, Py_ssize_t len_dest, Py_ssize_t len_src)
 {
-    while (copied < len_dest) {
-        Py_ssize_t items_to_copy = Py_MIN(copied, len_dest - copied);
-        memcpy(items + copied, items, sizeof(PyObject*) * items_to_copy);
-        copied += items_to_copy;
-    }
+        Py_ssize_t copied = len_src;
+        while (copied < len_dest) {
+            Py_ssize_t bytes_to_copy = Py_MIN(copied, len_dest - copied);
+            memcpy(dest + copied, dest, bytes_to_copy);
+            copied += bytes_to_copy;
+        }
 }
 
 extern PyObject* _PyType_AllocNoTrack(PyTypeObject *type, Py_ssize_t nitems);
diff --git a/Objects/listobject.c b/Objects/listobject.c
@@ -573,7 +573,7 @@ list_repeat(PyListObject *a, Py_ssize_t n)
             *dest++ = *src++;
         }
 
-        _objects_repeat(np->ob_item, input_size, output_size);
+        _objects_repeat((char *)np->ob_item, sizeof(PyObject *)*output_size, sizeof(PyObject *)*input_size);
     }
 
     Py_SET_SIZE(np, output_size);
@@ -752,7 +752,7 @@ list_inplace_repeat(PyListObject *self, Py_ssize_t n)
     for (Py_ssize_t j = 0; j < input_size; j++) {
         Py_INCREF_n(items[j], n-1);
     }
-    _objects_repeat(items, input_size, output_size);
+    _objects_repeat((char *)items, sizeof(PyObject *)*output_size, sizeof(PyObject *)*input_size);
 
     Py_INCREF(self);
     return (PyObject *)self;
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
@@ -535,7 +535,7 @@ tuplerepeat(PyTupleObject *a, Py_ssize_t n)
             *dest++ = *src++;
         }
 
-        _objects_repeat(np->ob_item, input_size, output_size);
+        _objects_repeat((char *)np->ob_item, sizeof(PyObject *)*output_size, sizeof(PyObject *)*input_size);
     }
     _PyObject_GC_TRACK(np);
     return (PyObject *) np;

Original file line number	Diff line number	Diff line change
`@@ -573,7 +573,7 @@ list_repeat(PyListObject *a, Py_ssize_t n)`
`573`	`573`	`dest++ = src++;`
`574`	`574`	`}`
`575`	`575`
`576`		`- _objects_repeat(np->ob_item, input_size, output_size);`
	`576`	`+ _objects_repeat((char )np->ob_item, sizeof(PyObject )output_size, sizeof(PyObject )*input_size);`
`577`	`577`	`}`
`578`	`578`
`579`	`579`	`Py_SET_SIZE(np, output_size);`
`@@ -752,7 +752,7 @@ list_inplace_repeat(PyListObject *self, Py_ssize_t n)`
`752`	`752`	`for (Py_ssize_t j = 0; j < input_size; j++) {`
`753`	`753`	`Py_INCREF_n(items[j], n-1);`
`754`	`754`	`}`
`755`		`- _objects_repeat(items, input_size, output_size);`
	`755`	`+ _objects_repeat((char )items, sizeof(PyObject )output_size, sizeof(PyObject )*input_size);`
`756`	`756`
`757`	`757`	`Py_INCREF(self);`
`758`	`758`	`return (PyObject *)self;`
Original file line number	Diff line number	Diff line change
`@@ -535,7 +535,7 @@ tuplerepeat(PyTupleObject *a, Py_ssize_t n)`
`535`	`535`	`dest++ = src++;`
`536`	`536`	`}`
`537`	`537`
`538`		`- _objects_repeat(np->ob_item, input_size, output_size);`
	`538`	`+ _objects_repeat((char )np->ob_item, sizeof(PyObject )output_size, sizeof(PyObject )*input_size);`
`539`	`539`	`}`
`540`	`540`	`_PyObject_GC_TRACK(np);`
`541`	`541`	`return (PyObject *) np;`