[Python-Dev] [Python-checkins] cpython (2.7): Backport early-out 91259f061cfb to reduce the cost of bb1a2944bcb6

[Benjamin Peterson]

On Tue, Oct 6, 2015, at 19:12, raymond.hettinger wrote:
> https://hg.python.org/cpython/rev/37aee118e1a3
> changeset:   98578:37aee118e1a3
> branch:      2.7
> parent:      98572:60c44a09c5fc
> user:        Raymond Hettinger <python at rcn.com>
> date:        Tue Oct 06 23:12:02 2015 -0400
> summary:
>   Backport early-out 91259f061cfb to reduce the cost of bb1a2944bcb6
> 
> files:
>   Modules/_collectionsmodule.c |  6 +++++-
>   1 files changed, 5 insertions(+), 1 deletions(-)
> 
> 
> diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
> --- a/Modules/_collectionsmodule.c
> +++ b/Modules/_collectionsmodule.c
> @@ -651,6 +651,9 @@
>      Py_ssize_t n;
>      PyObject *item;
>  
> +    if (Py_SIZE(deque) == 0)
> +        return;
> +

dequeue is not varsized in Python 2.7, so using Py_SIZE() is incorrect.