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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/67809] Empty pointer-chasing loops aren't optimized out
Date: Fri, 02 Oct 2015 09:29:00 -0000	[thread overview]
Message-ID: <bug-67809-4-YfjqkQANdO@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-67809-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67809

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
We indeed do not have a flag to tell GCC it's ok to remove infinite loops with
no side-effects.  We assume the dereferences will not trap (unless
-fexceptions -fnon-call-exceptions) and GCC happily removes possible traps
so I don't think that would prevent the DCE here.  What prevents DCE is
that the loop might not terminate.  There isn't any "infinite loop is undefined
behavior" thing so clang removing the loop is an invalid transform.


  reply	other threads:[~2015-10-02  9:29 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-01 20:47 [Bug middle-end/67809] New: " matt at godbolt dot org
2015-10-02  9:29 ` rguenth at gcc dot gnu.org [this message]
2015-10-02  9:52 ` [Bug middle-end/67809] " glisse at gcc dot gnu.org
2021-06-12 12:30 ` gareth@ignition-web.co.uk
2021-08-28 23:52 ` pinskia at gcc dot gnu.org

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