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From: "dcb314 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/108718] New: csmith: possible bad code with -O2
Date: Wed, 08 Feb 2023 13:53:24 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108718

            Bug ID: 108718
           Summary: csmith: possible bad code with -O2
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Created attachment 54432
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54432&action=3Dedit
C source code

The attached C code, produced by csmith, does this:

$ ../results/bin/gcc -w -O1 bug883.c && ./a.out
checksum =3D 7A94E377
$ ../results/bin/gcc -w -O2 bug883.c && ./a.out
checksum =3D 842F1622
$=20

The bug seems to exist since sometime before 20220703

$ ../results.20220703/bin/gcc -w -O2 bug883.c && ./a.out
checksum =3D 842F1622
$=20

I will have a go at a reduction.=