[Bug tree-optimization/80641] missed optimization with with std::vector resize in loop

[Bug tree-optimization/80641] missed optimization with with std::vector resize in loop

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80641

--- Comment #15 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is interesting:
  _48 = _149 + 18446744073709551612; // _149 - 4
  _63 = _55 + _48;
  _18 = _63 - _55;
  _19 = _18 /[ex] 4;
  _20 = (long unsigned int) _19;
  if (_55 != _63)

_18 should be the same as _48
and the if statement should be if (_48 != 0)

[Bug tree-optimization/80641] missed optimization with with std::vector resize in loop

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80641

--- Comment #16 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note starting in GCC 13 at -O3, we are able to optimize this all the way to:
```
int f ()
{
  int * _54;

  <bb 2> [local count: 114863531]:
  _54 = operator new (16);
  MEM <uint128_t> [(char * {ref-all})_54] = 0x30000000200000001;
  operator delete (_54, 16);
  return 0;

}
```
If we change the name of the function to f rather than main. In GCC 14 we able
to optimize even without the name change (there has been some inlining heurstic
changes there).