PNaCl documentation: add SIMD vectors.

native_client_sdk/doc_generated/reference/pnacl-undefined-behavior.html

Index: native_client_sdk/doc_generated/reference/pnacl-undefined-behavior.html
diff --git a/native_client_sdk/doc_generated/reference/pnacl-undefined-behavior.html b/native_client_sdk/doc_generated/reference/pnacl-undefined-behavior.html
index e10c67bb03fa7bb051258f4a2523326131e2bd63..272b4a7bfb813e97fe0e89577681f10eac81706f 100644
--- a/native_client_sdk/doc_generated/reference/pnacl-undefined-behavior.html
+++ b/native_client_sdk/doc_generated/reference/pnacl-undefined-behavior.html
@@ -13,7 +13,8 @@
 <ul class="small-gap">
 <li><a class="reference internal" href="#potentially-fixable" id="id7">Potentially Fixable</a></li>
 <li><a class="reference internal" href="#floating-point" id="id8">Floating-Point</a></li>
-<li><a class="reference internal" href="#hard-to-fix" id="id9">Hard to Fix</a></li>
+<li><a class="reference internal" href="#simd-vectors" id="id9">SIMD Vectors</a></li>
+<li><a class="reference internal" href="#hard-to-fix" id="id10">Hard to Fix</a></li>
 </ul>
 </li>
 </ul>
@@ -174,6 +175,16 @@ SIMD operations.</li>
 function implementation isn&#8217;t, e.g. <code>std::min</code> and <code>std::max</code>), is
 well-defined in the <em>pexe</em>.</li>
 </ul>
+</section><section id="simd-vectors">
+<h4 id="simd-vectors">SIMD Vectors</h4>
+<p>SIMD vector instructions aren&#8217;t part of the C/C++ standards and as such
+their behavior isn&#8217;t specified at all in C/C++; it is usually left up to
+the target architecture to specify behavior. Portable Native Client
+instead exposed <a class="reference internal" href="/native-client/reference/pnacl-c-cpp-language-support.html#portable-simd-vectors"><em>Portable SIMD Vectors</em></a> and
+offers the same guarantees on these vectors as the guarantees offered by
+the contained elements. Of notable interest amongst these guarantees are
+those of alignment for load/store instructions on vectors: they have the
+same alignment restriction as the contained elements.</p>
 </section><section id="hard-to-fix">
 <h4 id="hard-to-fix">Hard to Fix</h4>
 <ul class="small-gap">