<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/148830>148830</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang optimizer produces incorrect arithmetic result with global pointers in loops
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          Dong-hui-li
      </td>
    </tr>
</table>

<pre>
    ## Description
When compiling code with global pointer operations and type casting in loops, Clang optimizer produces incorrect arithmetic results at -O2 optimization level.

## Environment
- **Clang version**: 14.0.0
- **Operating System**: Linux
- **CPU**: x86_64
- **Optimization level**: -O2
- **GCC version**: 11.4.0 (for comparison)

## Steps to Reproduce
1. Create `test.c` file with the following content:
```
#include <stdio.h>
#include <string.h>

int *a;
int b;

int main() {
    char d[16];
    memset(d, 170, 16);

[clang_bug.zip](https://github.com/user-attachments/files/21232124/clang_bug.zip)

 for (int c = 0; c < 16; c++) {
        a = (int*)&d[c];
        b = *a + c;
    }
    printf("Result: %d\n", b);
    return 0;
}
```
2. Compile with Clang: clang-14 -O2 test.c -o test_clang
3. Run the program: ./test_clang
4. Output: Result: 185
5. Compile with GCC (for comparison):gcc -O2 test.c -o test_gcc
6. Run the GCC version:./test_gcc
7. Output: Result: 1048761
## Expected Result
Consistent output matching GCC: `Result: 1048761`

## Actual Result
Clang outputs incorrect result: `Result: 185`

## Additional Notes
1. The issue occurs only at optimization level -O2 and above
2. GCC produces consistent results across all versions
3. This miscompilation may affect security-critical applications

</pre>
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