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

[pinskia at gcc dot gnu.org via Gcc-bugs]

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

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Sam James from comment #3)
>     manager_deserialize takes ~1s instead of ~0.2s

I looked into manager-serialize.c and its code generation with and without
-ftrivial-auto-var-init=zero and there is no obvious issues there. 

The only major thing I saw different was:
  MEM <unsigned long> [(void *)&__unique_prefix_i12] = 4294967294;

vs
  __unique_prefix_i12.idx = 4294967294;

where idx is of type unsigned.

that is -2 aka _IDX_ITERATOR_FIRST.

There is padding after the idx field so storing zero there is fine.