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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/96966] [8/9/10/11 Regression] redundant
 memcpy not eliminated after pointer subtraction
Date: Mon, 07 Sep 2020 23:46:43 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96966

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|redundant memcpy not        |[8/9/10/11 Regression]
                   |eliminated after pointer    |redundant memcpy not
                   |subtraction                 |eliminated after pointer
                   |                            |subtraction
      Known to work|                            |8.1.0, 8.2.0
      Known to fail|                            |10.2.0, 11.0, 7.3.0, 8.3.0,
                   |                            |9.2.0
           Keywords|                            |missed-optimization

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
According to Godbolt, GCC 8.1 and 8.2 emit optimal code for both functions =
but
GCC 8.3 emits the less optimal code for f and has g jump to it.  Starting w=
ith
10.1, GCC emits the same suboptimal code for both functions.=