<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 --- - implement __builtin_assume_aligned()"
   href="http://llvm.org/bugs/show_bug.cgi?id=16294">16294</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>implement __builtin_assume_aligned()
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </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>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>conradsand.arma@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>Hello,

Thanks for your work on clang.  It would be very useful to implement the
__builtin_assume_aligned() function, which allows the compiler to assume that
the returned pointer is aligned (to a user specified number of bytes). This can
help in automatic vectorisation, allowing the compiler to use aligned SSE2
instructions.

GCC 4.7+ has this:
<a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html">http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html</a>

The __builtin_assume_aligned() function is used to speed up software such as
the Armadillo C++ linear algebra library:
<a href="http://arma.sourceforge.net/">http://arma.sourceforge.net/</a></pre>
        </div>
      </p>
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