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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/114923] gcc ignores escaping pointer and applies
 invalid optimization
Date: Thu, 02 May 2024 19:07:10 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114923

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

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

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Escape means something different from memory being written.

In C (and C++), memory writes to some variable is modeled such that it is n=
ot
known to write to another location
So you need to add a compiler barrier here.
Note `atomic_signal_fence (memory_order_relaxed)` might be enough. Note also
the order of the writes to reg1 and reg2 might happen in a different order =
in
HW so you need to have a full (HW) write barrier between them to make sure =
the
write is done in the correct order.=