<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/66733>66733</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            `(a == 0) & (((short)a) >= 0)` is not always optimized to just `a == 0`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          pinskia
      </td>
    </tr>
</table>

<pre>
    Take:
```
int f(int a)
{
 short b = a;
        _Bool t = a == 0;
        _Bool t1 = b >= 0;
 return t & t1;
}
void f0(int a, int *b)
{
        *b= f(a) != 0;
}
void f01(int a, int *b)
{
        _Bool c = f(a);
 *b= c;
}
void f01_(int a, _Bool *b)
{
        _Bool c = f(a);
        *b= c;
}
_Bool f00(int a)
{
        return f(a);
}
void f00_(int a, _Bool *b)
{
        _Bool c = f00(a);
        *b= c;
}
_Bool f1(int a)
{
        _Bool t = a == 0;
        short t1 = a;
        _Bool t2 = t1 >= 0;
 return t & t2;
}
```
`f`, `f00` and `f1` should all produce the same optimized code of just `a == 0;` While `f0`, `f01`, `f01_` and `f00_` all should produce `*b = a == 0;` But currently `f`, `f0`, f01` all still have the short comparison `>=` being included.

I am filing this because the way LLVM is acting here seems like `((short)a) < 0` is being transformed too early to `(a >> 15) & 1` and then never going back sometimes. This happens on x86_64, aarch64, riscv and BPF targets.
</pre>
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