[llvm-bugs] [Bug 50495] New: wrong code at -O3 on x86_64-linux-gnu

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=50495

            Bug ID: 50495
           Summary: wrong code at -O3 on x86_64-linux-gnu
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Interprocedural Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: zhendong.su at inf.ethz.ch
                CC: llvm-bugs at lists.llvm.org

[585] % clangtk -v
clang version 13.0.0 (https://github.com/llvm/llvm-project.git
5dd86aadf0b014913bd35bb7435808eb081bc049)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/opfuzz/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
[586] %
[586] % clangtk -O2 small.c; ./.aout
bash: ./.aout: No such file or directory
[587] %
[587] %
[587] % clangtk -v
clang version 13.0.0 (https://github.com/llvm/llvm-project.git
5dd86aadf0b014913bd35bb7435808eb081bc049)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/opfuzz/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
clang-13: warning: argument unused during compilation: '-I
/usr/local/include/csmith' [-Wunused-command-line-argument]
[588] %
[588] % clangtk -O2 small.c; ./a.out
[589] %
[589] % clangtk -O3 small.c
[590] % ./a.out
Floating point exception
[591] %
[591] % cat small.c
int a, b, e[2], f;
static char c, d, *g = &c, **h = &g;
char i(char j, char k) { return k ? j % k : 0; }
int main() {
  int *l = &e[1];
  for (; d < 1; d++) {
    int *m = &a, *o = &e[1];
    **h = l == m;
    char ***n[2] = {&h, &h};
    for (; b < 4; ++b)
      if (f != 1)
        *o = i(1, *g);
  }
  return 0;
}

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