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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/115395] [15 regression] libarchive miscompiled with -O2 -march=znver2 -fno-vect-cost-model since r15-1006-gd93353e6423eca
Date: Mon, 10 Jun 2024 07:31:51 +0000	[thread overview]
Message-ID: <bug-115395-4-3lGndWws2N@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-115395-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115395

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
It needs epilogue vectorization to trigger and it's the path re-using the
vector accumulator from the earlier loop that goes wrong when the main
vector loop is skipped.

We apply the initial value adjustment to the scalar result but the
continuation fails to do this and the epilogue vector epilogue expects
the earlier code to have done it.

IIRC we force "optimization" of this to be disabled but obviously somehow
fail to do this for SLP.

  parent reply	other threads:[~2024-06-10  7:31 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-06-08 12:24 [Bug tree-optimization/115395] New: [15 regression] libarchive miscompiled with -O2 -march=znver2 -fno-vect-cost-model sjames at gcc dot gnu.org
2024-06-08 12:30 ` [Bug tree-optimization/115395] " pinskia at gcc dot gnu.org
2024-06-08 12:37 ` pinskia at gcc dot gnu.org
2024-06-08 13:45 ` [Bug tree-optimization/115395] [15 regression] libarchive miscompiled with -O2 -march=znver2 -fno-vect-cost-model since r15-1006-gd93353e6423eca sjames at gcc dot gnu.org
2024-06-08 16:11 ` sjames at gcc dot gnu.org
2024-06-10  6:39 ` rguenth at gcc dot gnu.org
2024-06-10  7:31 ` rguenth at gcc dot gnu.org [this message]
2024-06-10  8:03 ` rguenth at gcc dot gnu.org
2024-06-10  9:39 ` cvs-commit at gcc dot gnu.org
2024-06-10  9:49 ` rguenth at gcc dot gnu.org
2024-06-10 11:20 ` sjames at gcc dot gnu.org

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