<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/121757>121757</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [i386][Float128][compiler-rt] compiler-rt lack of __subtf3 symbol
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          zhangtianhao6
      </td>
    </tr>
</table>

<pre>
    
The __subtf3 function is automatically generated by the subtraction compiler of the float 128 type. However, the compiler rt library of the i386 architecture does not provide the __subtf3 function. The libgcc provides the __subtf3 function. Why does this difference exist? Can we make up for it or  do not allow the compiler to automatically generate the __subtf3 function?

case
```
#include <iostream>

int main() {
    // 创建两个 __float128 类型的变量
    __float128 a = 1.23456789012345678901234567890123456789Q;  // 精度较高
    __float128 b = 0.12345678901234567890123456789012345678Q;

    // 执行减法，编译器将自动使用 __subtf3
    __float128 result = a - b;

    return 0;
}
```
float

use compiler-rt error: -rtlib=compiler-rt -m32
use libgcc ok: -m32
https://godbolt.org/z/3YT3PbPEW
</pre>
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