What does the --abi-compile=yes option of CUDA ptxas do (which costs registers)?
<p>NVIDIA CUDA's PTX optimizing assembler, <code>ptxas</code>, has the following option:</p>

<pre><code>--abi-compile &lt;yes|no&gt;                              (-abi)                      
        Enable/Disable the compiling of functions using ABI.
        Default value:  'yes'.
</code></pre>

<p>What ABI is that? And what happens when you disable it? It <em>seems</em> to result in fewer registers being used, hmm...</p>

<p><sub>(Question inspired by <a href="http://on-demand.gputechconf.com/gtc-express/2011/presentations/register_spilling.pdf" rel="nofollow">this GTC 2011 presentation</a> about register spilling.)</sub></p>