<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/63764>63764</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Wrong code at -O3 on x86_64-linux_gnu (latent issue in DSEPass since clang-9)
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          shao-hua-li
      </td>
    </tr>
</table>

<pre>
    This looks like a long latent issue since clang-9. Clang at -O3 produces wrong code on the following code. `opt-bisect-limit` suggests that the issue might be in `DSEPass`. 

Compiler explorer: https://godbolt.org/z/YqG6YMefq

```console
% cat a.c
int printf(const char *, ...);
long a;
char b;
int c, e;
int *d = &c;
static int f;
int main() {
  {
    int g = e = f = 1;
 for (; f >= 0; f--) {
      char h[4];
      for (; g < 4; g++)
 h[e - 1 + g] = 5;
      a = 0;
      for (; a <= 0; a++) {
 char *i = &b;
        for (; g < 7; g++)
          ;
        *i = *d = h[3];
      }
    }
  }
  printf("%d\n", b);
}
%
% clang-tk -O0 a.c && ./a.out
5
% clang-tk -O3 a.c && ./a.out
0
%
% clang-tk -v
clang version 17.0.0 (https://github.com/llvm/llvm-project.git 99074aafc31593c9935da483edab1333d6ce5a5b)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /zdata/shaoli/compilers/ccbuilder-compilers
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Candidate multilib: .;@m64
Selected multilib: .;@m64
%
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy0VU2P2zgP_jXMhbChSP6IDzlkkrp4Dy-6QAsseipkSbG1o0ipJXdm99cvpDhOZjo7wAJdI1Aoinz4IYrk3uveKrWF8gHKw4pPYXDj1g_cZcPEM6NXnZN_br8M2qNx7tGj0Y8KORpnezQ8KBtQez8p9NoKhcJw22dNjvtIIA-YfWJ4Hp2chPL4NEY94aRCZzEMCo_OGPekZ26OUBF3DlmnvRIhM_qkA1QE_dT3ygePYeAhKV6snnQ_BOwUahtVD58__Ma9h4rkCOQAZHdZ9-501kaNqJ7Pxo1qBLbDIYSzB7YD2gJteyc7Z0Luxh5o-xfQ9uv3j9XX_6vj93skqMjlJ5z1zqiZS0sUPCDPxYWhbcDzqG04At1E0YBi4CMC3QHdY57nQBtgDxfplE2-bJNkt2wjloha6gUL6E4isAMCrcRy4gMPWmAUOL4QP3FtgW6ANgj1zMd7EpNSnyBVWo9pXS8weHQxgg2wh3T2IR6TtMuyV8DxS3EMUD4UUB5uKOm7g4om91gkEuhD-jWzbNRWmOEagcbj8pB8Kl-hcby68g82osB-cZcvZu5cvt6Pvia1ewX3htP1m04v308Ad_Dz5cUA2c_pgfpw295t7silvIBSoKWEcm8TucfuvrgWFaDlXbWmhxoeMftEYtnGgIFWmANtee6mcBF9W4O9o0HeNfZjrvDUHX6o0WtncV3nJCcxs6-epA7D1OXCnYC2xvy4_mXn0f2hRMh7HbBpSF1wfhRsXTZMNA0rJS82TEnerRljshKq5GW3XM8XPvYqxAbwvKm-VUU22UfrnmxmtJ2es95Os9wwKi7x5KQyUfrsvH6-HP3P-sCNUfKgUyeJDUPywIG2sXcaDbQVc8vxkRbdpI1UY3bjJqDWTVai4FZqyYPCj_s96gs4D9rZGXzyYwxddzEpQgBtZ9dvLtN2Tf4DzPWvx5yv4bMySgQlf4l_-8Wz02SCjlpsh3l8AwU5VcUrk-8J3Qr32ulXcstkwxq-Utt1tdk06w1pyGrYFmvWCCW5KotOsWNXF5wqSchGdLLhvF7pLSWUkZo067IsSpLXx2MjGkJpXW3qQmygIOrEtcljWcfRs0pjbVuxuipWhnfK-OtwHrep9rup91AQo33wN7Wgg1Hb32_jdZ68zuJ92r71dorv7MXk1hbnuflyiANtVtNotv_uUQJtE2ys-xTG3wEAAP__6BdiGg">