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<p class="MsoNormal">Hi Markus,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">So therefore if one wanted to use these intrinsics one would have to<o:p></o:p></span></i></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">define __RDRND__ on the commandline.<o:p></o:p></span></i></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Defining __RDRND__ on command line is not preferred, you should use -mrdrnd.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<pre><i><span style="color:black">I am now wondering if it would make sense to enable intrinsics such as<o:p></o:p></span></i></pre>
<pre><i><span style="color:black">the above (ones that aren't dependent on /arch: ) by default when<o:p></o:p></span></i></pre>
<pre><i><span style="color:black">compiling for an MSVC target?<o:p></o:p></span></i></pre>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I don’t think it makes sense. We have many features that are not categorized under the /arch. Default enabling them is neither effective nor credible (we do require a mechanism like /arch to make sure these features are available on user’s
platform).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<pre><i><span style="color:black">And besides, without looking at clangs headers it is currently<o:p></o:p></span></i></pre>
<pre><i><span style="color:black">impossible to find out how to enable these intrinsics as it's<o:p></o:p></span></i></pre>
<pre><i><span style="color:black">undocumented which defines one would have to set on the command line<o:p></o:p></span></i></pre>
<pre><i><span style="color:black">to enable these.<o:p></o:p></span></i></pre>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">You don’t need to do so. I recommend to use option march instead. It represents a lot of such features like “rdrnd” that are supporting on the given architecture. E.g. sandybridge, haswell, skylake etc.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks<o:p></o:p></p>
<p class="MsoNormal">Pengfei<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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