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    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - ThinLTO build has undefined symbols due to powf-ldexpf translation"
   href="https://bugs.llvm.org/show_bug.cgi?id=38139">38139</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>ThinLTO build has undefined symbols due to powf-ldexpf translation
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>new-bugs
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Windows NT
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>new bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>dmajor@mozilla.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, llvm@inglorion.net, peter@pcc.me.uk, tejohnson@google.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Here's another issue from the Firefox ThinLTO build
(<a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1448976">https://bugzilla.mozilla.org/show_bug.cgi?id=1448976</a>)

It's interesting that the source file references `powf` and yet the missing
symbol is `ldexpf`. I assume the compiler is attempting some optimization
there.

Presumably, whatever MSVC library we're linking against would be able to
provide an implementation for `powf`, but it doesn't have one for `ldexpf`
(maybe it's an inline function in the MS headers or something?).

$ cat mathutil.cpp
extern "C" float powf(float, float);
int main(int argc, char** argv) {
  return powf(2.0f, argc);
}

$ clang-cl -c mathutil.cpp -O1 -flto=thin

$ lld-link -nodefaultlib -entry:main mathutil.obj
lld-link.exe: error: undefined symbol: ldexpf
<span class="quote">>>> referenced by lto.tmp:(main)</span ></pre>
        </div>
      </p>


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