[Bug tree-optimization/116101] New: [14/15 Regression] isel duplicates comparisons even at -O0

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116101

            Bug ID: 116101
           Summary: [14/15 Regression] isel duplicates comparisons even at
                    -O0
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: internal-improvement
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take this gimple testcase:
```

int __GIMPLE() f(int a, int b, int c, int d, int e)
{
  _Bool t;
  int ff;
  int gg;
  int res;
  t = a == b;
  ff = t ? a : e;
  gg = t ? d : b;
  res = ff+gg;
  return res;
}
```

At -O0, isel will duplicate the comparison for `a == b` even at -O0 (or rather
when -fno-tree-ter is in effect). We should disable at -O0 (maybe when
-fno-tree-ter).