<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/88100>88100</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Inconsistent Output on Different Optimization Levels for Uninitialized Structure Member Reference
        </td>
    </tr>

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

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

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

<pre>
    
When compiling this code using Clang++ with the -O0 optimization level, the program executes successfully(see https://godbolt.org/z/6G4evhKE1). However, when using optimization levels -O1, -O2, or -O3, the program consistently returns an error code of 200(see https://godbolt.org/z/x9dzrd75j).
I am seeking clarification on whether this behavior can be considered a bug or a deliberate design choice.
# Version
```sh
clang version 19.0.0git (https://github.com/llvm/llvm-project.git 987087df90026605fc8d03ebda5a1cd31b71e609)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/cTest/llvm-project/mybuild/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Candidate multilib: .;@m64
Selected multilib: .;@m64
```
# Command
`clang++ -fsanitize=undefined -O2 bug.c`
# Code
`cat bug.c`
```c
struct S {
  int a;
};

int main() {
  struct S s;
  struct S *p = &s;
 return p->a;
}
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJysVNtu4zYTfhr6ZiCBomRZutBFYq_2X_wtAjTb9rKgyJHEXYo0eHAOT1_QcuKsCxQtUMAwxTl-881wuPdqMogd2d6T7WHDY5it6xRfuLHmZbHRC78ZrHzpCD0Qevf7jAaEXY5KKzNBmJUHYSVC9Om-19xMhN0Tdg9PKswQZoTsgYI9BrWoVx6UNaDxhJqw_Vl7dHZyfAF8RhEDevBRCPR-jFq_ENZ4RJhDOHpS3hHWE9ZPVg5Wh9y6ibD-lbC-_lzhaf7_p4KwNof_2Sc8oUsJnhLcFdpfEXjIHopklT2wdFgH2UN5i0tY45UPaIJ-AYchOuOBG0DnrFtrtyMwSv8h1udWvjq5235LWFdSvwBfwCN-TziF5k6NSqxArUk1hBndyvWAMz-plJgbGHBFJ9GhBA5DnFIRHCRqNaDjAUFi6jCI2SqBl3yElfAbOq-suQhquv78vApE6iOcVhso2pzmdFIBCGtu6lNhjkMu7EJYr_Xp7ciOzn5DEfLk1TY72uzk2FLK6ppuR9FIWuIg-ZYXQpbFsCuwpi1h7Zr-K3cTBlLewXNT_1FXWTTfjX0ymVYmPmeTiRe72SGXsFiJOlkfrVfPF06ND1xrlAflkoqwfrYLEtaLr-jDDUzC-uVliEpLwvpBXWjpbTQyMS2VTFx-3u9BrXHP3bnEjd6lcGpIfAiReryivqJl_aWyR9QoAsr_Itb-HdgSdVDJqbyDnJT3pKJLXd1k_Duj9wG4DsjeLgs38l0vPjztbPTcqKBekZSHaCSOyqBM7yjNYC5uAkm8RuHh1uQttVjvPrgoAjwC2d2vEgBlAvAEefXYHa7f5_-kX7gyhDWEtR8936P5d5cPQsLujkDKAxBWfzBYXzkcM1J--jHtj4g3sitlW7Z8g12xK1hdtW1DN3PX1hWVhaSiLGrKRFFVQ1HzCuUgyt0oxEZ1jLKKVrSlDa0ZzbEeq6GkRcu53OK2IhXFhSudpylN22OjvI_YNU1B6UbzAbV_W9quO4_yECdPKqqVD_7qFlTQ2H0x1zUGDzEcY0ir5aDGEd1Z9nE7_rRux9E6-NWo1Giu1StKeDwTFx3Cz7gM6OAXPPsL3ESnu3-3GgjrzzV5wvpzWX8GAAD__xUoDCI">