[Python-checkins] cpython: call_function(): document PyMethod optimization

[victor.stinner]

https://hg.python.org/cpython/rev/c085f2e0e1af
changeset:   105385:c085f2e0e1af
user:        Victor Stinner <victor.stinner at gmail.com>
date:        Mon Nov 28 18:32:31 2016 +0100
summary:
  call_function(): document PyMethod optimization

files:
  Python/ceval.c |  6 +++++-
  1 files changed, 5 insertions(+), 1 deletions(-)


diff --git a/Python/ceval.c b/Python/ceval.c
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4736,7 +4736,11 @@
     }
     else {
         if (PyMethod_Check(func) && PyMethod_GET_SELF(func) != NULL) {
-            /* optimize access to bound methods */
+            /* Optimize access to bound methods. Reuse the Python stack
+               to pass 'self' as the first argument, replace 'func'
+               with 'self'. It avoids the creation of a new temporary tuple
+               for arguments (to replace func with self) when the method uses
+               FASTCALL. */
             PyObject *self = PyMethod_GET_SELF(func);
             Py_INCREF(self);
             func = PyMethod_GET_FUNCTION(func);

-- 
Repository URL: https://hg.python.org/cpython