<div dir="ltr">I agree with David's sentiment.  The second method appears to be easier to follow.  IMHO, this would be easier for external users that desire to modify the backend for their own custom extensions/instructions.  </div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Aug 18, 2017 at 5:05 AM, David Chisnall <span dir="ltr"><<a href="mailto:David.Chisnall@cl.cam.ac.uk" target="_blank">David.Chisnall@cl.cam.ac.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On 18 Aug 2017, at 10:55, Alex Bradbury <<a href="mailto:asb@asbradbury.org">asb@asbradbury.org</a>> wrote:<br>
><br>
> I've demonstrated both the "conventional" approach<br>
> <<a href="https://gist.github.com/asb/0c61ebc131076c6186052c29968a491d#file-riscvinstrinfo_conventional-td" rel="noreferrer" target="_blank">https://gist.github.com/asb/<wbr>0c61ebc131076c6186052c29968a49<wbr>1d#file-riscvinstrinfo_<wbr>conventional-td</a>><br>
> and the "separate patterns" approach<br>
> <<a href="https://gist.github.com/asb/0c61ebc131076c6186052c29968a491d#file-riscvinstrinfo_separate_pats-td" rel="noreferrer" target="_blank">https://gist.github.com/asb/<wbr>0c61ebc131076c6186052c29968a49<wbr>1d#file-riscvinstrinfo_<wbr>separate_pats-td</a>>.<br>
> Obviously once patterns and pseudo-instructions are separated out, you may<br>
> want to move them to a different .td file.<br>
><br>
> Does anyone have strong views on these sort of choices one way or another?<br>
<br>
</span>I do find the second easier to follow, though both are a lot easier to read than the MIPS back end.<br>
<span class="HOEnZb"><font color="#888888"><br>
David<br>
<br>
</font></span></blockquote></div><br></div>