<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/75997>75997</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Increasing the Hamming distance for defense programming may be optimized by the compiler.
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          zhou-shan
      </td>
    </tr>
</table>

<pre>
    1. The code that caused the error is as follows:(test.c)
`enum {
TEST_XXX_ENABLED = 0x5AA55AA5;
TEST_XXX_DISABLED = 0xA55AA55A;
};
static uint32_t g_test_xxx_flag = TEST_XXX_DISABLED;

attribute ((noline)) bool test_xxx_is_enable(void)
{
return g_test_xxx_flag == TEST_XXX_ENABLED;
}

attribute ((noline)) bool test_xxx_enable(void)
{
g_test_xxx_flag = TEST_XXX_ENABLED;
}`
2. The optimization level is Os.
3. Problem Description:
The function works normally, but the secure programming design (increasing the Hamming distance) is optimized by the compiler. In the final generated executable program:
- The size of g_test_xxx_flag is reduced from 4 bytes to 1 byte.
- The operations of assigning and comparing g_test_xxx_flag are both replaced with 0/1.
We expect to generate the following assembly instruction sequence:

</pre>
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