[Bug tree-optimization/118081] New: wrong code at -O{s,2,3} with "-fno-tree-vrp -fno-expensive-optimizations" on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118081

            Bug ID: 118081
           Summary: wrong code at -O{s,2,3} with "-fno-tree-vrp
                    -fno-expensive-optimizations" 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 appears to be a recent regression as it doesn't reproduce with 14.2 and
earlier. 

Compiler Explorer: https://godbolt.org/z/o9xxKG86M


[617] % 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/15.0.0/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 15.0.0 20241217 (experimental) (GCC) 
[618] % 
[618] % gcctk -O3 small.c; ./a.out
[619] % 
[619] % gcctk -O3 -fno-tree-vrp -fno-expensive-optimizations small.c
[620] % ./a.out
Segmentation fault
[621] % 
[621] % cat small.c
int a, b, c, d[1];
int e(int f) { return f ? f || 0 : f; }
void g() {
  char h;
  int i;
  b = a ? a : 1;
  i = e(1 ^ b);
  h = i - 8;
  if (h)
    return;
  d[c] = 0;
}
int main() {
  c = 5000;
  g();
  return 0;
}