[Bug c/110702] New: Wrong code at -O1 on x86_64-linux-gnu (regression since GCC-12.2)

[shaohua.li at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110702

            Bug ID: 110702
           Summary: Wrong code at -O1 on x86_64-linux-gnu (regression
                    since GCC-12.2)
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
  Target Milestone: ---

This looks like a regression since GCC-12.2.

Compiler explorer: https://godbolt.org/z/655af97j7

$ cat a.c
int printf(const char *, ...);
int a, b, c, d;
long e[9][7][4];
void f() {
  for (; a >= 0; a--) {
    b = 0;
    for (; b <= 3; b++) {
      c = 0;
      for (; c <= 3; c++) {
        int *g = &d;
        *g = e[0][0][b] | e[a][b][a];
      }
    }
  }
}
int main() {
  f();
  printf("%d\n", a);
}
$
$ gcc-tk -O0 a.c && ./a.out
-1
$ gcc-tk -O1 a.c && ./a.out
0
$
$ gcc-tk -v
Using built-in specs.
COLLECT_GCC=gcc-tk
COLLECT_LTO_WRAPPER=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-322d17ae51ea0137167424e0018d7fa355948f9f/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --disable-multilib --disable-bootstrap
--enable-languages=c,c++
--prefix=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-322d17ae51ea0137167424e0018d7fa355948f9f
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20230711 (experimental) (GCC) 
$