<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/111338>111338</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [ppc64le] Clang-18 emits machine code that cannot be linked with GNU ld
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          rui314
      </td>
    </tr>
</table>

<pre>
    It looks like clang-18 creates an object file that cannot be linked with GNU ld. To see the issue, you can just run the following shell script on a PPC64LE machine (or, alternatively you can run it with `docker run --platform ppc64le --rm -it -v /home/ruiu/mold:/mold ubuntu:24.04`).

```shell
CC=clang-18

cat <<EOF | $CC -c -fPIC -o a.o -xc -
void foo();
void (*get_foo())() { return foo; }
EOF

$CC -shared -o b.so a.o

cat <<EOF | $CC -c -fno-PIE -o c.o -xc -
#include <stdio.h>

__attribute__((ifunc("resolve_foo"))) void foo(void);
void real_foo(void) { printf("foo "); }
void (*resolve_foo())() { return real_foo; }

void (*get_foo())();

int main() {
  printf("%p\n", foo);
}
EOF

$CC -o exe ./c.o ./b.so -no-pie
./exe
```

The error is shown below.

```
$ bash -x bug.sh
+ CC=clang-18
+ cat
+ clang-18 -c -fPIC -o a.o -xc -
+ clang-18 -shared -o b.so a.o
+ cat
+ clang-18 -c -fno-PIE -o c.o -xc -
+ clang-18 -o exe ./c.o ./b.so -no-pie
./c.o: in function `main':
-:(.text+0x94): R_PPC64_TOC16_HA for indirect function `foo' unsupported
/usr/bin/ld: ./c.o: R_PPC64_TOC16_HA against foo is not supported by glibc as a dynamic relocation
-:(.text+0x98): R_PPC64_TOC16_LO for indirect function `foo' unsupported
clang-18: error: linker command failed with exit code 1 (use -v to see invocation)
```

The above error doesn't occur if you built the code with GCC. When I compare the LLVM's object file with GCC-generated one, I noticed that GCC generates different code for ifunc functions. I believe LLVM should generate the same code as GCC's.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJyUVltv4jgU_jXm5ShRcEiABx5oWmYrdbfVanb3ETnOCfHUsZEvlP77lR3ChJ2ZzqyEEuOcy3fuh1krDgpxQ4o7UtzPmHedNhvjRT5fzGrdvG8eHUitXy1I8YrAJVOHZL4CbpA5tMAU6PoLcgetkAiuYw44U0o7qBGkUK_YwJtwHXz64y-QTQqfNVgMlAjCWo-EVvCufeCCL946MF7Fr62WUr8JdQDboZRguRFHB1oBg5eXqlw8PUDPeCcUAqErbYIkJh0axZw4oXy_yg0ihRtwkDJrNH9FE2-T5CiZa7Xp4Xjk5UIiJInpIREOkhMQuut0j4TujBee0F2vZUPy7eUEvvbKeZJv6SLNFqTMCF2nJLsn2fbyLLPhF20Y7qqK5PejJ6fEnDkgeUXy6uF5B2RZAaGLqoKEQ9K-PFaQaGCphuTMIRlYTlo00GpN6IrQNcnvJtfxbntAt_9KEH7hAGR5BwadNyqy53dAlvcD88Pz7saEAYPtmMEmQKhTG3H8MnSlk5fHh8DKb9ETmgvFpW8wMFvXCJ12JH-YSt7vmXNG1N7hfh_Br0TrFY9HatBqecLBQjpauIaJX8LxG98YZHJ_8z165GiEcu0gutUaLjKn3pm49kb5D917VTWV8othuoIenkI56JlQX5UM93ADnNDiSIpKxWM1eGEi6eMwa8AzQkroLsQqvGO4E6WTo8CBNNziGf-T4VNhnzsENEYbEBZsp98U1Cj12_dr4woAamY7SM5Q-0Nqu_H-Dr5XMvQOOHOTP2Nv-qBcbul-mNIfi_4gnaekv-pJnmqSb0EoCGnthFahRw1hXoZeEymT2HVWqcOzI_QuO68XMapb-HMfu-H-83M1L_e_baENbleNMLEtT2TGTFiCV9Yfj9o4bEbcO29NABh07mKHgwm0bzSwAxPKupBaIcCh219FQv0OBylqDswCg-ZdsV5wMCg1ZwHJj-xZfdeep-f_b881UfLtkIXhEGeRAa77nqkGWibkOJrwLBxw3SDMQzV6i6H3u2FQCXUagdP1T1Ke1fo0Jn6j0YYIOtCcewOijeOo9kK6ON-iwmE0VlUK_3So4DHgOzIzzMenp79_J3Rpb0bsyJEcUKFhweNaxSn6GAIhODbDGP5UVTDSWGhE26JBdTE0-jT48upQm8JjKFKBp0FzqFsvm6uMCMmy_oKc2aAhwEtnzSZv1vmazXAzX9IVXa6Kopx1mzLj66LIWclpsWrnTbGiZYZFuyjKdZaxeiY2NKOLeZYts4LSvEwXRZvPS96u1rhcF9iQRYY9EzKV8tSn2hxmcWnYzOfzPF_NJKtR2ri-UKrwbVwpaNhmzCYwJbU_WLLIpLDOfhXjhJNx77mMfVLcQzXWLvbC2etyEc396WYz80ZuOueOdtgPCN0dhOt8nXLdh6qSp_GVHI0OASV0F_FaQncXg04b-m8AAAD__33Z16E">