[llvm-bugs] [Bug 51683] New: wrong code at -O1 and above with -fPIC on x86_64-linux-gnu

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51683

            Bug ID: 51683
           Summary: wrong code at -O1 and above with -fPIC on
                    x86_64-linux-gnu
           Product: new-bugs
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: zhendong.su at inf.ethz.ch
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org

[653] % clangtk -v
clang version 14.0.0 (https://github.com/llvm/llvm-project.git
705d00578128c6089fe05adb175a5306f46c695c)
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
[654] %
[654] % clangtk -O1 small.c; ./a.out
[655] %
[655] % clangtk -O1 -fPIC small.c
[656] % ./a.out
Segmentation fault
[657] %
[657] % cat small.c
int printf(const char *, ...);
int a = -2094967296, b = 6, h, i;
char c;
static const int d, *e[2] = {&d, &d};
int f;
unsigned g = 1;
int main() {
  int j, k = ~a;
 L:;
  unsigned m = (2 / ~c) / g;
  int o = c = m % b;
  if (g >= o && c) {
    printf("%d", f);
    for (; h; h++)
      printf("0");
    i = *e[j];
    goto L;
  }
  if (b < 6)
    j++;
  if (k <= 0)
    goto L;
  return 0;
}

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