[Bug tree-optimization/125783] New: csinc should be prefered pver cinv for `a ? 1 : -1`

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125783

            Bug ID: 125783
           Summary: csinc should be prefered pver cinv for `a ? 1 : -1`
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64

I noticed these 2 functions have different code generation (at -O2) but they
are exactly the same code:
```
int ff(int a)
{
    return a == 0 ? 1 : -1;
}

int ff1(int a)
{
    return a != 0 ? -1 : 1;
}
```
The results:
```
ff:
        cmp     w0, 0
        mov     w0, 1
        csinv   w0, w0, wzr, eq
        ret
ff1:
        cmp     w0, 0
        mov     w0, -1
        csinc   w0, w0, wzr, ne
        ret
```

csinc seems more prefered.