[llvm-bugs] [Bug 52496] New: wrong code at -O1 on x86_64-linux-gnu

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=52496

            Bug ID: 52496
           Summary: wrong code at -O1 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

It appears to be a regression from 12.*. 

[758] % clangtk -v
clang version 14.0.0 (https://github.com/llvm/llvm-project.git
8ed8d370880b5c4e7bbf52b50791710a9f4f834b)
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
[759] % 
[759] % clangtk -O0 -w small.c; ./a.out
[760] % 
[760] % clangtk -O1 -w small.c
[761] % ./a.out
Aborted
[762] % 
[762] % cat small.c
int printf(const char *, ...);
int a, *b;
int main() {
  int *c, *d, e;
  while (a) {
    int f[1];
    while (a)
      printf(c);
    c = f;
    b = (int *)&d;
  }
L:
  e = 1;
  if (a) {
    printf("%d", a);
    b = &e;
    (*c)++;
  }
  if (a)
    goto L;
  if (!e)
    __builtin_abort();
  return 0;
}

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