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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/108737] [13 Regression] Apparent miscompile
 of infinite loop on gcc trunk in cddce2 pass
Date: Thu, 09 Feb 2023 14:04:57 +0000
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X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: needs-bisection
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108737

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Apparent miscompile of      |[13 Regression] Apparent
                   |infinite loop on gcc trunk  |miscompile of infinite loop
                   |in cddce2 pass              |on gcc trunk in cddce2 pass
   Last reconfirmed|                            |2023-02-09
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Target Milestone|---                         |13.0
           Keywords|                            |needs-bisection
          Component|c++                         |tree-optimization
            Version|unknown                     |13.0

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
C++ has the forward progress guarantee, in case 'x' is false there's an end=
less
loop which is undefined behavior.

Now, the same happens with C and with -fno-finite-loops, so there's somethi=
ng
amiss here.

-funswitch-loops is necessary, but GCC 12 doesn't seem to be affected ...=