<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/63611>63611</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Wrong code at -Os on x86_64-linux_gnu (a recent regression)
        </td>
    </tr>

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

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

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

<pre>
    This seems to be a recent regression. clang at -Os produced the wrong code.

Compiler explorer: https://godbolt.org/z/Yvo1c3efK

```console
% cat a.c
unsigned a;
unsigned *c = &a;
char g;
char *h = &g, *i;
unsigned *const *j = &c;
unsigned *const **k = &j;
unsigned *const ***l = &k;
int m(unsigned n) {
  while (n << 4)
    n = 4;
  while (n)
    ;
  return 1;
}
int *e;
int **f = &e;
int o() {
  int b;
  *h = i != &i;
ac:
  if ((**l || *h) & *h - 2079077697)
    ;
  else {
    int d;
    for (; *l; g++)
      for (; *h <= 0;) {
        *f = 0;
        return m(****l) + ****l;
      }
    goto ac;
  }
  return 0;
}
int main() { o(); }
%
% clang-tk -O0 a.c && ./a.out
%
% clang-tk -Os a.c
% ./a.out
Killed
%
% clang-tk -v
clang version 17.0.0 (https://github.com/llvm/llvm-project.git 36999318f09122fa41baff838f46c753db078275)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/compiler-explorer/clang-trunk/bin
Found candidate GCC installation: /opt/compiler-explorer/gcc-9.2.0/lib/gcc/x86_64-linux-gnu/9.2.0
Selected GCC installation: /opt/compiler-explorer/gcc-9.2.0/lib/gcc/x86_64-linux-gnu/9.2.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
 "/opt/compiler/clang-trunk-20230629/bin/clang-17" -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -mrelax-all -dumpdir /app/output.s- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name example.c -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debug-info-kind=constructor -dwarf-version=4 -debugger-tuning=gdb -v -fcoverage-compilation-dir=/app -resource-dir /opt/compiler/clang-trunk-20230629/lib/clang/17 -internal-isystem /opt/compiler/clang-trunk-20230629/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /opt/compiler/gcc-9.2.0/lib/gcc/x86_64-linux-gnu/9.2.0/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdebug-compilation-dir=/app -ferror-limit 19 -fgnuc-version=4.2.1 -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/example-329967.o -x c <source>
clang -cc1 version 17.0.0 based upon LLVM 17.0.0git default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/opt/compiler≈Ω/gcc-9.2.0/lib/gcc/x86_64-linux-gnu/9.2.0/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /opt/compiler-explorer/clang-trunk-20230629/lib/clang/17/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
%
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy8V1uP6ygS_jXkpYTl4LRjP-QhnbRnRzOjkXZGM9qnFoayw2kMFuDunP31K2zn0unLOUcrTRQldtXHRxV1Abj3qjWIG3J3T-72Cz6Eg3Ubf-CWHgZOtVrUVn7d_HlQHjxi5yFYqBE4OBRoAjhsHXqvrElAaG5a4AHo7x56Z-UgUEI4ILw4a1oQVmJC0j1Jt9Pvzna90ugAj722Dh3JtnAIofck2xJWEVa1VtZWh8S6lrDqv4RV_3m2S5Fh88s1E8nT6Sus8VbjLGV3IHgAnohJMJjRXwmcZPc3IsK2Aki2B8Lyi1ocuIP29Sth28MJ2RK2iwL1PqE1PsSHLye8-BxH2PbpBP3yTShhW31CP53RygToCCvOowxhJZD1rAZ4OSiNQFhhgGQ7ku1gRVh50gKYkXN1Jrwe8Qp4hXAYBmdgeRaR9f5iDmFbfGXfZHxzMv610hJW3JgcxfXVdOcQKCBsObNcYsBFTKDT2AZGwuK8YusdWY9RO4zTsHzio8DSdZmu13m5_shP1B6vDZtMk1cIgMa6ccbsPvLq-N8Sdj9-r1hvgYcpGntII9tr_6fPecnSV_PFz7z-3dnN2dnJwXt4LXw9-hyq-NLaYIGL67W-qOdZ0vej3HFlLqE7hXH07gQj7O6qNGO_oOEJ6O9prNEYiRiMhLCKJ3YIn4_xl7qOmptRvyitUX7K8DzX9Ni2ntHFLgbLdZImaQzLTSNS4TDUibAdYZXWz6c_2jv7BUVIWhUgy8uyzJZFk5ZLxhq-Wta8aYqsaFa5WN9lsk7XBVvfnfPgT-5aDLHtHYv8MV_RwTwZ-2KoVmY40tYMM-7gkEvorEQd0b316jipfjY-8OjrXo39k7DK9oGwSszdlZ67K6tm591gngiramUmjsoORoLgRirJA8JPux2oiZcHZc03eVshaJmwJI2roupJQlg1e3XxhlUTbJz2D9QoAsp_ar7d2cFu0EHFgdkWkpjNq7TLV5-hMjbDMvYZ7HjGHU_As5efTQqEsTcevw4YZSnL0pyVc-ROyuWaMAZUiCXQ4FSv8cNkAoqdCtTWX4B2DjU_Uq41UDl0vVSxGVW876MdQ-iHkHgKVCrPa420cYhAhUbuKPeB1thYh7Tm4gmNvODGonhGpxqFbhQL7iR95npAaniHHmjsFLRRehIAHnnXa0zEZJUVYxLQMduhVwJorwTV-Iwa2PSiPO0VAu0axzukvVUmxPPDfvSn6Xg4UHTOWKBN01NhTXBcBJLtrQHaGEtdzHllWhqxQLtxY3WDCNZRrhX30dBmMC_KSBqia55kewY0jDVLRT_Edab5CmgYDI6CFg26aLDEemipMo2lT8pIku2v-IHKF-4aOvccku1X84gWXSRTpiXZvpU10GegjbDP6HiLdEqMaXVkLPf9FDGgDr0dnEA6h_F7E2kqnlFJWLVcAx0X0nBNlf_qA3b_DxthlTJCDxLf5x18JIsB19-CvjHhh1sAq5Lk7c878Ld24DE-iLemz9B3eD4f_eNTAG2mnPo4Bxp0zjqqVacCLEugTWsGcZ1lCUuWYz5p66hUvDXWByVionMpnVct0P3j40-73eO_tn89PO7_3v67Yo-76ufH7R-_kWy_BGqjaaGLXWKuW5qxsszXiQV6hHiG3k25SLKH6x127FA322zNPUoYemvg11__-m0Wx61UYsMHHWCqtm9sj6o11inTgrEGj8qHeDWRymGstq_v99YHRoqSFAXZPZBt-U8kVDTj-829HURYdkoFwlgS52LgkTtxAB-4Cx4O6PB88L3GZ7uIzx4-w3_3weH7Cv5C-m6R36o_LqSPkKP4wUiwzcktrXxIbo98p5vhQm4yWWYlX-BmmRdFWhRZWS4OG5mxVYN5Vq9ywbFcsxWv70Ser_mK1fUqXajN5HGWpkuWZ2UisZEFrtYirZuVyBqySrHjSidx74tX1YXyfsBNnuXL5ULzGrUfr9iMGXyBURnjerdfuM24X9ZD68kqjQ74C0tQQePm7_Pl-XS3tgauV-kxthvCincu5YSVi8HpzY-dZeMqRxs9YdXow_8CAAD__yb02rg">