Issue #27786: Simplify x_sub()

vstinner · vstinner · commit 8bcf312d093c · 2016-08-17T19:48:33.000+02:00
The z variable is known to be a fresh number which cannot be shared, Py_SIZE()
can be used directly to negate the number.
diff --git a/Objects/longobject.c b/Objects/longobject.c
@@ -3000,9 +3000,7 @@ x_sub(PyLongObject *a, PyLongObject *b)
     }
     assert(borrow == 0);
     if (sign < 0) {
-        _PyLong_Negate(&z);
-        if (z == NULL)
-            return NULL;
+        Py_SIZE(z) = -Py_SIZE(z);
     }
     return long_normalize(z);
 }

Original file line number	Diff line number	Diff line change
`@@ -3000,9 +3000,7 @@ x_sub(PyLongObject a, PyLongObject b)`
`3000`	`3000`	`}`
`3001`	`3001`	`assert(borrow == 0);`
`3002`	`3002`	`if (sign < 0) {`
`3003`		`- _PyLong_Negate(&z);`
`3004`		`- if (z == NULL)`
`3005`		`- return NULL;`
	`3003`	`+ Py_SIZE(z) = -Py_SIZE(z);`
`3006`	`3004`	`}`
`3007`	`3005`	`return long_normalize(z);`
`3008`	`3006`	`}`