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From: "jwzeng at nuaa dot edu.cn" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/111151] New: [12/13/14 Regression] Wrong code at -O0
 on x86_64-pc-linux-gnu
Date: Fri, 25 Aug 2023 06:39:39 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111151

            Bug ID: 111151
           Summary: [12/13/14 Regression] Wrong code at -O0 on
                    x86_64-pc-linux-gnu
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jwzeng at nuaa dot edu.cn
  Target Milestone: ---

Link to the Compiler Explorer: https://godbolt.org/z/MY4Er6b3e

The following code snippet, gcc at -O0 produces the wrong code. I also comp=
iled
this code with almost all versions up to and including gcc-13 and got the s=
ame
error.

$ cat test.c
int printf(const char *, ...);
short t =3D -32166;
unsigned long long int a, b, c;
int main()
{
    a =3D 32739 > t + 4503599ULL ? 32739 : t + 4503599ULL;
    b =3D -10 * a;
    printf("%llu (Split calculation result)\n", b);
    c =3D -10 * (32739 > t + 4503599ULL ? 32739 : t + 4503599ULL);
    printf("%llu (Combine calculation result)\n", c);
}
$
$ gcc-tk test.c; ./a.out
18446744073664837286 (Split calculation result)
18446744073709224226 (Combine calculation result)
$
$ clang-tk test.c; ./a.out
18446744073664837286 (Split calculation result)
18446744073664837286 (Combine calculation result)
$
$ ccomp test.c; ./a.out
18446744073664837286 (Split calculation result)
18446744073664837286 (Combine calculation result)
$
$ gcc-tk --version
gcc (GCC) 14.0.0 20230823 (experimental) [master r14-3395-g6cd8527307]
$
$ clang-tk --version
Ubuntu clang version 18.0.0
(++20230821052626+634b2fd2cac2-1~exp1~20230821172748.738)
$
$ ccomp --version
The CompCert C verified compiler, version 3.12=