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From: "dcb314 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/113727] New: csmith: differences from nothing to -O1
Date: Fri, 02 Feb 2024 19:40:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113727

            Bug ID: 113727
           Summary: csmith: differences from nothing to -O1
           Product: gcc
           Version: 14.0
            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 57298
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D57298&action=3Dedit
C source code

The attached C code seems to produce different answers
between no optimisation flags and -O1:

foundBugs $ ../results/bin/gcc -w bug1002.c
foundBugs $ valgrind -q ./a.out 1 > 0
foundBugs $ ../results/bin/gcc -w -O1 bug1002.c
foundBugs $ valgrind -q ./a.out 1 > 1
foundBugs $ diff 0 1=20
469,478c469,478
< ...checksum after hashing g_994.f3 : 5F99C263
< ...checksum after hashing g_994.f4 : 6E61EEE1
< ...checksum after hashing g_994.f5 : 8A4973F3
< ...checksum after hashing g_994.f6 : 1A47F5E1
< ...checksum after hashing g_994.f7 : CD2C240E
< ...checksum after hashing g_994.f8 : 7E61A9F
< ...checksum after hashing g_1368 : 74B15A31
< ...checksum after hashing g_1659 : 322B1FCB
< ...checksum after hashing g_1720 : 65F2763C
< checksum =3D 65F2763C
---
> ...checksum after hashing g_994.f3 : 3D4A5D24
> ...checksum after hashing g_994.f4 : 23E1696C
> ...checksum after hashing g_994.f5 : B115BFA4
> ...checksum after hashing g_994.f6 : E3A4BBDA
> ...checksum after hashing g_994.f7 : D44B3E01
> ...checksum after hashing g_994.f8 : 656901A2
> ...checksum after hashing g_1368 : 3B45689
> ...checksum after hashing g_1659 : EBA715C1
> ...checksum after hashing g_1720 : BDD5FC31
> checksum =3D BDD5FC31

I have a reduction running.=20

The bug first seems to occur sometime between dates 20231001 and 20231119.=
=20
Git hashes are g:5f3da480e7541a9c and eaeaad3fcac4d7a3.=