<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Sep 14, 2009, at 11:41 PM, Chris Lattner wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div><br>On Sep 14, 2009, at 5:13 PM, Nate Begeman wrote:<br><br><blockquote type="cite">Author: sampo<br></blockquote><blockquote type="cite">Date: Mon Sep 14 19:13:12 2009<br></blockquote><blockquote type="cite">New Revision: 81813<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">URL: <a href="http://llvm.org/viewvc/llvm-project?rev=81813&view=rev">http://llvm.org/viewvc/llvm-project?rev=81813&view=rev</a><br></blockquote><blockquote type="cite">Log:<br></blockquote><blockquote type="cite">Add an "original alignment" field to load and store nodes. This enables the<br></blockquote><blockquote type="cite">DAG Combiner to disambiguate chains for loads and stores of types which are<br></blockquote><blockquote type="cite">broken up by the Legalizer into smaller pieces.<br></blockquote><br>Hi Nate,<br><br><blockquote type="cite">+ //! OrigAlign - The original alignment of this MemSDNode in the case where<br></blockquote><blockquote type="cite">+ // this node was created by legalize from a MemSDNode with known alignment.<br></blockquote><blockquote type="cite">+ unsigned OrigAlign;<br></blockquote><br>I don't understand what this means. Is this saying that the load/store is always an access to [ptr_with_some_alignment]+SVOffset?<br><br>If so, it seems that the ultimate alignment of the access is actually:<br> MinAlign(OrigAlign, SVOffset)<br>(from MathExtras.h).<br><br>If this is true, then you can make the comment much more strong, and fix MemSDNode to never actually store the alignment of the access (store OrigAlign instead and compute the access alignment when needed).<br><br>If we do need to keep both alignments around, is there any way to encode this in SubclassData like the alignment field itself is to avoid growing MemSDNode (the biggest sdnode)?<font class="Apple-style-span" color="#000000"><font class="Apple-style-span" color="#144FAE"><br></font></font></div></blockquote><br></div><div>Thanks for the feedback, I'm working on it.</div><div><br></div><div>Cheers,</div><div>Nate</div><br></body></html>