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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/102902] [12 Regression] -O3 produces code that uses an uninitialized variable but originally was not used by r12-3876
Date: Mon, 17 Jan 2022 13:09:36 +0000 [thread overview]
Message-ID: <bug-102902-4-nGEsOteuRc@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102902-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102902
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P1
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
PR100810 is P1 so lets make this one, too. Just to say, the bug will be very
difficult to fix for good because fundamentally a default def SSA looks
like to have the same value for two different uses but the way we handle it
means that guarantee is violated. It's difficult to cure that not only because
former defs can become undefs. We'd need a way to stabilize the value on
an uninit use but without sacrifying optimization (for uses in PHI nodes).
next prev parent reply other threads:[~2022-01-17 13:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-22 17:35 [Bug tree-optimization/102902] New: wrong code at -O3 on x86_64-linux-gnu (generated code hangs) zhendong.su at inf dot ethz.ch
2021-10-22 18:53 ` [Bug tree-optimization/102902] [12 Regression] " pinskia at gcc dot gnu.org
2021-10-22 21:20 ` pinskia at gcc dot gnu.org
2021-10-25 8:44 ` [Bug tree-optimization/102902] [12 Regression] -O3 produces code that uses an uninitialized variable but originally was not used by r12-3876 marxin at gcc dot gnu.org
2021-10-25 8:45 ` marxin at gcc dot gnu.org
2021-10-25 8:57 ` marxin at gcc dot gnu.org
2021-10-25 8:58 ` rguenth at gcc dot gnu.org
2021-11-24 8:35 ` zhendong.su at inf dot ethz.ch
2021-11-24 8:44 ` pinskia at gcc dot gnu.org
2021-11-24 8:46 ` pinskia at gcc dot gnu.org
2022-01-17 13:09 ` rguenth at gcc dot gnu.org [this message]
2022-04-04 12:59 ` rguenth at gcc dot gnu.org
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