[Bug tree-optimization/114796] New: wrong code at -O2 with "-fno-tree-fre -fno-inline -fselective-scheduling2" on x86_64-linux-gnu

[zhendong.su at inf dot ethz.ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114796

            Bug ID: 114796
           Summary: wrong code at -O2 with "-fno-tree-fre -fno-inline
                    -fselective-scheduling2" on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

This seems quite long-latent and affects all versions 9.* and later. 

Compiler Explorer: https://godbolt.org/z/nKx6f4hjK

[526] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/14.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.1 20240421 (experimental) (GCC) 
[527] % 
[527] % gcctk -O0 small.c
[528] % ./a.out
[529] % 
[529] % gcctk -O2 -fno-tree-fre -fno-inline -fselective-scheduling2 small.c
[530] % ./a.out
Aborted
[531] % 
[531] % cat small.c
int printf(const char *, ...);
int a, b, c = -3, h, j, k;
struct d {
  int e;
  char f;
  char g;
};
int i, l, m;
char n[10][9] = {{1}};
struct d o = {1,0,0};
unsigned p;
void q(int s) { b = a; }
void r() {
  k = 0;
  while (k)
    while (l)
      while (i)
        if (m)
          while (1)
            ;
  for (; p < 1; p++) {
    if (j) {
      q(n[j][c]);
      if (h)
        printf("\n");
    }
    n[p][k] = 1;
  }
}
int main() {
  r();
  if (o.g != 0)
    __builtin_abort();
  return 0;
}