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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/111523] Unexpected performance regression with
 -ftrivial-auto-var-init=zero for e.g. systemctl unmask
Date: Fri, 01 Mar 2024 07:57:16 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111523

--- 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=3Dzero and there is no obvious issues there.=20

The only major thing I saw different was:
  MEM <unsigned long> [(void *)&__unique_prefix_i12] =3D 4294967294;

vs
  __unique_prefix_i12.idx =3D 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.=