[Bug tree-optimization/107273] New: wrong code at -O3 on x86_64-linux-gnu

zhendong.su at inf dot ethz.ch gcc-bugzilla@gcc.gnu.org
Sat Oct 15 20:53:04 GMT 2022


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107273

            Bug ID: 107273
           Summary: wrong code at -O3 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: ---

It appears to be a recent regression.

Compiler Explorer: https://godbolt.org/z/Mo8sPhYW7


[538] % 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/13.0.0/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
--with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20221015 (experimental) [master r13-3311-gbaeec7cc83b] (GCC) 
[539] % 
[539] % gcctk -O2 small.c; ./a.out
[540] % 
[540] % gcctk -O3 small.c
[541] % ./a.out
Segmentation fault
[542] % 
[542] % cat small.c
int printf(const char *, ...);
int a[1] = {1};
short b, c = 5500;
int d;
long e;
char f = 1;
int main() {
  while (1) {
    long g = b < 1;
    e = g;
    break;
  }
  for (; f; f--) {
    if (e) {
      d = -(6L | -(c & 1000));
    }
    char h = d;
    if (b)
      b = 0;
    if (d < 200)
      while (1)
        printf("%d", a[c]);
    short i = h * 210;
    c = i;
  }
  return 0;
}


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