[Bug middle-end/111523] Unexpected performance regression with -ftrivial-auto-var-init=zero for e.g. systemctl unmask

["pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111523

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |MOVED

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Turns out systemd had a 1MB buffer in their serializer formating code
(serialize_item_format) that would be executed a lot and
-ftrivial-auto-var-init=zero would cause this buffer to be zero'd each time the
function was called (a decent thing for this flag to do).

It just happens serialize_item_format is called a lot when it came
serialization. With arm memory systems being slower than most, it just exposed
this issue.

Anways systemd has now changed the buffer to 256 which is much much smaller and
for most calls enough in size before needing to reallocate the buffer that it
has now become fast.

Anyways -ftrivial-auto-var-init=zero just exposed a performance (stack size)
issue with already existing issue inside the systemd code. A good thing really. 

So closing as moved.