[Bug middle-end/111126] New: Not always using czero.eqz

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111126
            Bug ID: 111126
           Summary: Not always using czero.eqz
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: pinskia at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---
            Target: riscv* (with zicond)

Take:
```
int f(bool a, int c)
{
  return a * c;
}

int f0(bool a, int c)
{
  return (-a) & c;
}

int f1(bool a, int c)
{
  return a ? c : 0;
}

int f3(int a, int b, int c)
{
  return (a == b) * c;
}
int g0(bool a, int c)
{
  return a ? 0 : c;
}
int g1(bool a, int c)
{
  a = !a;
  return a * c;
}
```

Currently for f, f0 we emit:
```
        neg     a0,a0
        and     a0,a0,a1
```

Which is good for riscv without zicond but with we should just get the same as
f1.

f1 we do we:
```
        czero.eqz       a0,a1,a0
```

though without zicond we get:
```
        snez    a5,a0
        neg     a5,a5
        and     a0,a1,a5
```
Notice the extra snez (note the above is because that is ifcvt.cc doing the
emitting).

This is all about what is the canonical form of bool ? a : 0.