<html>
    <head>
      <base href="http://llvm.org/bugs/" />
    </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 --- - testcase we fail to devirtualize but gcc does"
   href="http://llvm.org/bugs/show_bug.cgi?id=18972">18972</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>testcase we fail to devirtualize but gcc does
          </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>Linux
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>normal
          </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>rafael.espindola@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Given

struct foo {
 virtual ~foo();
};
struct bar : public foo {
 virtual void zed();
};
void f() {
 foo *x(new bar);
 delete x;
}

clang at -O3 will produce a call via a vtable. It would be illegal to call
_ZN3barD0Ev, since we are not guaranteed by the ABI that it is available, but
what current gcc does instead is call _ZN3fooD2E.

To do this in llvm we would probably need one more linkage:
unavailable_but_known. The idea is that _ZN3barD0Ev is not
available_externally, it can be internal no another TU, but we know its value
anyway.</pre>
        </div>
      </p>
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