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From: "xry111 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/110791] [12/13/14 Regression] arm: Wrong code
 with -Os -march=armv8.1-m.main
Date: Mon, 24 Jul 2023 11:24:18 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: wrong-code
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X-Bugzilla-Who: xry111 at gcc dot gnu.org
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110791

Xi Ruoyao <xry111 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
                 CC|                            |xry111 at gcc dot gnu.org
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-07-24

--- Comment #1 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
Isn't this a UB?

  while (p >=3D path && *p !=3D '/')
    p--;

This will cause p to become "&main::path[0] - 1".  C23 6.5.6p9:

If the pointer operand and the result do not point to elements of the same
array object or one past the last element of the array object, the behavior=
 is
undefined.=