<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/70650>70650</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [LLVM][LTO] How to use dynamic library libLTO.so?!!
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          hippyll123
      </td>
    </tr>
</table>

<pre>
    I'm learning something about LTO，libLTO.so is mentioned in the following article,but when I use ld.lld and ld.gold,all of them do not use libLTO.so, I want know where is this dynamic library used.

command and code are as follows:
```c++
// use ld.gold
clang a.c -flto -c
clang b.c -flto -c
clang -flto a.o b.o -o main -fuse-ld=gold
or
// use ld.lld
clang a.c -flto -c
clang b.c -flto -c
clang -flto a.o b.o -o main -fuse-ld=gold

// ----- a.c ---
#include <stdio.h>

extern void foo1(void);
extern void foo4(void);

void foo2(void) {
  printf("Foo2\n");
}

void foo3(void) {
  foo4();
}

int main(void) {
  foo1();
}

// --- b.c ---
#include <stdio.h>

extern void foo2(void);

void foo1(void) {
  foo2();
}

void foo4(void) {
  printf("Foo4");
}
```

[https://llvm.org/docs/LinkTimeOptimization.html#phase-1-read-llvm-bitcode-files](url)
</pre>
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