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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114236] introduce unnecessary store operation
 when unrolling a loop
Date: Tue, 05 Mar 2024 15:17:18 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114236

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |WONTFIX
                 CC|                            |rguenth at gcc dot gnu.org

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Executing store motion of MEM[(short int *)&g_16] from loop 2
Re-issueing dependent store of *g_70.2_4 from loop 2 on exit 4 -> 5
Moving statement

The extra store is required to enable sinking of the store to g_16 as
we don't know whether g_70 points to aliased memory.

I think we fail to realize that *g_70 is loop invariant as well, but
what you observe is a feature - it allows reducing the number of stores
to g_16.=