https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110992
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|14.0 |13.3
Summary|[14 Regression] Dead Code |[13/14 Regression] missed
|Elimination Regression at |VRP optimization due to
|-O3 since |transformation of `a &
|r14-1654-g7ceed7e3e29 |-zero_one_valued_p` into `a
| |* zero_one_valued_p`
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, I think this is a ranger issue really.
Take:
```
int f(unsigned b, short c)
{
int bt = b;
int bt1 = bt;
int t = bt1 & -(c!=0);
// int t = bt1 * (c!=0);
if (!t) return 0;
foo(bt == 0);
return 0;
}
```
That `bt == 0` should be figured out that is 0 there. We could figure that out
in GCC 12 even. But in GCC 13+ we could not.
That is traced back to r13-793-g8fb94fc6097c but really the ranger should
figure out if you have a*b != 0, then both a and b should be non-zero ...
But currently that is not support ....
It looks like we only handle `a & b` that way ...
