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From: "tobi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/98552] Make more use of __builtin_undefined for assuring that variables do not change
Date: Wed, 06 Jan 2021 08:08:01 +0000	[thread overview]
Message-ID: <bug-98552-4-Uv7unSv0cF@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-98552-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98552

--- Comment #3 from Tobias Schlüter <tobi at gcc dot gnu.org> ---
Don't ask how long I'd been staring at the assembly in disbelief until I
figured out what had gone wrong :-)

In this particular case the problem can be addressed by passing &j into the
function instead of &i, so I wonder why the Fortran f.e. can't do that?  One
possible problem is that if j's address escapes (in the sense that the compiler
assumes that subsequent function calls can do whatever to it), you'd need a new
fake memory location.

  parent reply	other threads:[~2021-01-06  8:08 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-05 22:09 [Bug tree-optimization/98552] New: " tkoenig at gcc dot gnu.org
2021-01-05 22:10 ` [Bug tree-optimization/98552] " tkoenig at gcc dot gnu.org
2021-01-06  2:26 ` tobi at gcc dot gnu.org
2021-01-06  8:04 ` tkoenig at gcc dot gnu.org
2021-01-06  8:08 ` tobi at gcc dot gnu.org [this message]
2021-01-09 11:44 ` tkoenig at gcc dot gnu.org
2021-12-23  9:51 ` pinskia at gcc dot gnu.org

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