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From: "dcb314 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/108657] New: csmith: possible wrong checksum with -O3 and
 -ftrivial-auto-var-init=zero
Date: Fri, 03 Feb 2023 13:59:34 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108657

            Bug ID: 108657
           Summary: csmith: possible wrong checksum with -O3 and
                    -ftrivial-auto-var-init=3Dzero
           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 54402
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54402&action=3Dedit
C source code

For the attached C code, derived from csmith output, I get:

$ ~/gcc/results/bin/gcc -w bug880.c
$ ./a.out
checksum =3D F3A34B53
$ ~/gcc/results/bin/gcc -w -O2 bug880.c
$ ./a.out
checksum =3D F3A34B53
$ ~/gcc/results/bin/gcc -w -O2 -ftrivial-auto-var-init=3Dzero bug880.c
$ ./a.out
checksum =3D F3A34B53
$ ~/gcc/results/bin/gcc -w -O3 -ftrivial-auto-var-init=3Dzero bug880.c
$ ./a.out
checksum =3D BCC02729
$ ~/gcc/results/bin/gcc -w -O3  bug880.c
$ ./a.out
checksum =3D F3A34B53
$=20

Also, the possible bug seems to have first occurred sometime before 20230103

$ ~/gcc/results.20230103.asan.ubsan/bin/gcc -w -O3 -ftrivial-auto-var-init=
=3Dzero
bug880.c
$ ./a.out
checksum =3D BCC02729
$=