<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/107317>107317</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Inaccurate debug information in binaries compiled with "-O2" and "-O3"
        </td>
    </tr>

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

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

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

<pre>
    The debug information for variables within the for loop, particularly at line 25 and line 26, is misleading, consistently showing `global_shift = 0` and `global_var = 470777959` during step-in or step-over operations [(Godbolt)](https://clang.godbolt.org/z/T1aadhhsf). However, the final results are accurate. When a breakpoint is set at line 34, the debug information correctly displays `global_var = 9` and `global_shift = 16777200`.

This issue can be reproduced in LLVM version of 18.1.8, 17.0.6, and 16.0.3 :
```
clang -g -O3 -o 420_O3.out 420.c
clang -g -O2 -o 420_O2.out 420.c

(lldb) file 420_O3.out
(lldb) b 25
(lldb) r
[...]
* thread #1, name = '420_O3.out', stop reason = breakpoint 1.1
    frame #0: 0x0000555555555141 420_O3.out`main [inlined] func_1 at 420.c:25:20
   22       for (global_var = 4; global_var != 9; ++global_var)
   23       {
   24           unsigned char shift_val = 254;
-> 25                global_flag++;
   26           global_shift |= (0xF1BB << (*local_var_ptr)) | ((shift_val << 15) * ((*local_var_ptr << global_flag) >= (*global_ptr)));
   27       }
   28       return global_union;
(lldb) p global_var
(int) 470777959
(lldb) p global_shift
(unsigned int) 0

...
(lldb) s
(lldb) s
(lldb) s
...
(lldb) p global_shift
(unsigned int) 0
(lldb) p global_var
(int) 470777959

```

It also can be repoduced in GDB context:
```
$ gdb 420_O3.out
GNU gdb (Ubuntu 15.0.50.20240403-0ubuntu1) 15.0.50.20240403-git
....

(gdb) b 25
(gdb) r
[...]

(gdb) p global_var
$1 = 470777959
(gdb) p global_shift
$2 = 0
(gdb) s
(gdb) s
(gdb) s
(gdb) p global_var
$3 = 470777959
(gdb) p global_shift
$4 = 0




```

</pre>
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